Science.gov

Sample records for rms time resolution

  1. A multichannel time-to-digital converter ASIC with better than 3 ps RMS time resolution

    NASA Astrophysics Data System (ADS)

    Perktold, L.; Christiansen, J.

    2014-01-01

    The development of a new multichannel, fine-time resolution time-to-digital converter (TDC) ASIC is currently under development at CERN. A prototype TDC has been designed, fabricated and successfully verified with demonstrated time resolutions of better than 3 ps-rms. Least-significant-bit (LSB) sizes as small as 5 ps with a differential-non-linearity (DNL) of better than ±0.9 LSB and integral-non-linearity (INL) of better than ±1.3 LSB respectively have been achieved. The contribution describes the implemented architecture and presents measurement results of a prototype ASIC implemented in a commercial 130 nm technology.

  2. A 75 ps rms time resolution BiCMOS time to digital converter optimized for high rate imaging detectors

    NASA Astrophysics Data System (ADS)

    Hervé, C.; Torki, K.

    2002-04-01

    This paper presents an integrated time to digital converter (TDC) with a bin size adjustable in the range of 125 to 175 ps and a differential nonlinearity of ±0.3%. The TDC has four channels. Its architecture has been optimized for the readout of imaging detectors in use at Synchrotron Radiation facilities. In particular, a built-in logic flags piled-up events. Multi-hit patterns are also supported for other applications. Time measurements are extracted off chip at the maximum throughput of 40 MHz. The dynamic range is 14 bits. It has been fabricated in 0.8 μm BiCMOS technology. Time critical inputs are PECL compatible whereas other signals are CMOS compatible. A second application specific integrated circuit (ASIC) has been developed which translates NIM electrical levels to PECL ones. Both circuits are used to assemble board level TDCs complying with industry standards like VME, NIM and PCI.

  3. Impulsive sound source localization using peak and RMS estimation of the time-domain beamformer output

    NASA Astrophysics Data System (ADS)

    Seo, Dae-Hoon; Choi, Jung-Woo; Kim, Yang-Hann

    2014-12-01

    This paper presents a beamforming technique for locating impulsive sound source. The conventional frequency-domain beamformer is advantageous for localizing noise sources for a certain frequency band of concern, but the existence of many frequency components in the wide-band spectrum of impulsive noise makes the beamforming image less clear. In contrast to a frequency-domain beamformer, it has been reported that a time-domain beamformer can be better suited for transient signals. Although both frequency- and time-domain beamformers produce the same result for the beamforming power, which is defined as the RMS value of its output, we can use alternative directional estimators such as the peak value to enhance the performance of a time-domain beamformer. In this study, the performance of two different directional estimators, the peak and RMS output values, are investigated and compared with the incoherent measurement noise embedded in multiple microphone signals. The impulsive noise source is modeled as a triangular pulse, and the beamwidth and side lobe level of the time-domain beamformer are formulated as functions of the pulse duration, the microphone spacing, and the number of microphones. The proposed formula is verified via experiments in an anechoic chamber using a uniformly spaced linear array, and the results show that the peak estimation of beamformer output determines the location with better spatial resolution and a lower side lobe level than RMS estimation.

  4. Real-time RMS active damping augmentation: Heavy and very light payload evaluations

    NASA Technical Reports Server (NTRS)

    Demeo, Martha E.; Gilbert, Michael G.; Lepanto, Janet A.; Flueckiger, Karl W.; Bains, Elizabeth M.; Jensen, Mary C.

    1994-01-01

    Controls-Structures Integration Technology has been applied to the Space Shuttle Remote Manipulator System (RMS) to improve on-orbit performance. The objective was to actively damp undesired oscillatory motions of the RMS following routine payload maneuvering and Shuttle attitude control thruster firings. Simulation of active damping was conducted in the real-time, man-in-the-loop Systems Engineering Simulator at NASA's Johnson Space Center. The simulator was used to obtain qualitative and quantitative data on active damping performance from astronaut operators. Using a simulated three-axis accelerometer mounted on the RMS, 'sensed' vibration motions were used to generate joint motor commands that reduced the unwanted oscillations. Active damping of the RMS with heavy and light attached payloads was demonstrated in this study. Five astronaut operators examined the performance of active damping following operator commanded RMS maneuvers and Shuttle thruster firings. Noticeable improvements in the damping response of the RMS with the heavy, Hubble Space Telescope payload and the very light, astronaut in Manipulator Foot Restraint payload were observed. The potential of active damping to aid in precisely maneuvering payloads was deemed significant.

  5. Probabilistic reasoning over seismic RMS time series: volcano monitoring through HMMs and SAX technique

    NASA Astrophysics Data System (ADS)

    Aliotta, M. A.; Cassisi, C.; Prestifilippo, M.; Cannata, A.; Montalto, P.; Patanè, D.

    2014-12-01

    During the last years, volcanic activity at Mt. Etna was often characterized by cyclic occurrences of fountains. In the period between January 2011 and June 2013, 38 episodes of lava fountains has been observed. Automatic recognition of the volcano's states related to lava fountain episodes (Quiet, Pre-Fountaining, Fountaining, Post-Fountaining) is very useful for monitoring purposes. We discovered that such states are strongly related to the trend of RMS (Root Mean Square) of the seismic signal recorded in the summit area. In the framework of the project PON SIGMA (Integrated Cloud-Sensor System for Advanced Multirisk Management) work, we tried to model the system generating its sampled values (assuming to be a Markov process and assuming that RMS time series is a stochastic process), by using Hidden Markov models (HMMs), that are a powerful tool for modeling any time-varying series. HMMs analysis seeks to discover the sequence of hidden states from the observed emissions. In our framework, observed emissions are characters generated by SAX (Symbolic Aggregate approXimation) technique. SAX is able to map RMS time series values with discrete literal emissions. Our experiments showed how to predict volcano states by means of SAX and HMMs.

  6. RMS active damping augmentation

    NASA Technical Reports Server (NTRS)

    Gilbert, Michael G.; Scott, Michael A.; Demeo, Martha E.

    1992-01-01

    The topics are presented in viewgraph form and include: RMS active damping augmentation; potential space station assembly benefits to CSI; LaRC/JSC bridge program; control law design process; draper RMS simulator; MIMO acceleration control laws improve damping; potential load reduction benefit; DRS modified to model distributed accelerations; accelerometer location; Space Shuttle aft cockpit simulator; simulated shuttle video displays; SES test goals and objectives; and SES modifications to support RMS active damping augmentation.

  7. High resolution time interval meter

    DOEpatents

    Martin, A.D.

    1986-05-09

    Method and apparatus are provided for measuring the time interval between two events to a higher resolution than reliability available from conventional circuits and component. An internal clock pulse is provided at a frequency compatible with conventional component operating frequencies for reliable operation. Lumped constant delay circuits are provided for generating outputs at delay intervals corresponding to the desired high resolution. An initiation START pulse is input to generate first high resolution data. A termination STOP pulse is input to generate second high resolution data. Internal counters count at the low frequency internal clock pulse rate between the START and STOP pulses. The first and second high resolution data are logically combined to directly provide high resolution data to one counter and correct the count in the low resolution counter to obtain a high resolution time interval measurement.

  8. Status report of RMS active damping augmentation

    NASA Technical Reports Server (NTRS)

    Gilbert, Mike; Demeo, Martha E.

    1993-01-01

    A status report of Remote Manipulator System (RMS) active damping augmentation is presented. Topics covered include: active damping augmentation; benefits of RMS ADA; simulated payload definition; sensor and actuator definition; ADA control law design; Shuttle Engineering Simulator (SES) real-time simulation; and astronaut evaluation.

  9. A model for the energy-dependent time-lag and rms of the heartbeat oscillations in GRS 1915+105

    NASA Astrophysics Data System (ADS)

    Mir, Mubashir Hamid; Misra, Ranjeev; Pahari, Mayukh; Iqbal, Naseer; Ahmad, Naveel

    2016-04-01

    Energy-dependent phase lags reveal crucial information about the causal relation between various spectral components and about the nature of the accretion geometry around the compact objects. The time-lag and the fractional root mean square (rms) spectra of GRS 1915+105 in its heartbeat oscillation class/ρ state show peculiar behaviour at the fundamental and harmonic frequencies where the lags at the fundamental show a turn around at ˜10 keV, while the lags at the harmonic do not show any turn around at least till ˜20 keV. The magnitude of lags is of the order of few seconds and hence cannot be attributed to the light travel time effects or Comptonization delays. The continuum X-ray spectra can roughly be described by a disc blackbody and a hard X-ray power-law component and from phase-resolved spectroscopy, it has been shown that the inner disc radius varies during the oscillation. Here, we propose that there is a delayed response of the inner disc radius to the accretion rate such that r_{in}(t)∝ dot{m}^β (t-τ_d). The fluctuating accretion rate drives the oscillations of the inner radius after a time delay τd while the power-law component responds immediately. We show that in such a scenario a pure sinusoidal oscillation of the accretion rate can explain not only the shape and magnitude of energy-dependent rms and time-lag spectra at the fundamental, but also the next harmonic with just four free parameters.

  10. 14. NBS REMOTE MANIPULATOR SIMULATOR (RMS) CONTROL ROOM. THE RMS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. NBS REMOTE MANIPULATOR SIMULATOR (RMS) CONTROL ROOM. THE RMS CONTROL PANEL IS IDENTICAL TO THE SHUTTLE ORBITER AFT FLIGHT DECK WITH ALL RMS SWITCHES AND CONTROL KNOBS FOR INVOKING ANY POSSIBLE FLIGHT OPERATIONAL MODE. THIS INCLUDES ALL COMPUTER AIDED OPERATIONAL MODES, AS WELL AS FULL MANUAL MODE. THE MONITORS IN THE AFT FLIGHT DECK WINDOWS AND THE GLASSES THE OPERATOR WEARS PROVIDE A 3-D VIDEO PICTURE TO AID THE OPERATOR WITH DEPTH PERCEPTION WHILE OPERATING THE ARM. THIS IS REQUIRED BECAUSE THE RMS OPERATOR CANNOT VIEW RMS MOVEMENTS IN THE WATER WHILE AT THE CONTROL PANEL. - Marshall Space Flight Center, Neutral Buoyancy Simulator Facility, Rideout Road, Huntsville, Madison County, AL

  11. How to squeeze high quantum efficiency and high time resolution out of a SPAD

    NASA Technical Reports Server (NTRS)

    Lacaita, A.; Zappa, F.; Cova, Sergio; Ripamonti, Giancarlo; Spinelli, A.

    1993-01-01

    We address the issue whether Single-Photon Avalanche Diodes (SPADs) can be suitably designed to achieve a trade-off between quantum efficiency and time resolution performance. We briefly recall the physical mechanisms setting the time resolution of avalanche photodiodes operated in single-photon counting, and we give some criteria for the design of SPADs with a quantum efficiency better than l0 percent at 1064 nm together with a time resolution below 50 ps rms.

  12. A spectral-timing analysis of the kHz QPOs in 4U 1636-53: the frequency-energy resolved RMS spectrum

    NASA Astrophysics Data System (ADS)

    Ribeiro, Evandro M.; Mendez, Mariano; Zhang, Guo-Bao; De Avellar, Márcio G. B.

    2016-07-01

    Our understanding of quasi-periodic oscillations (QPO) has been further advanced in the last few years by the use of combined spectral and timing techniques, and it is now clear that QPO properties are closely related to the spectral state of the source in which they appear. In this work we used all the available RXTE observations of the neutron-star low-mass X-ray binary 4U~1636-53 to study the properties of the kilohertz QPO as a function of energy and frequency. By following the frequency evolution of the kHz QPOs we created frequency-resolved fractional RMS spectra. We also studied the connection between the frequency of the kHz QPOs and the parameters of the model that fits the X-ray energy spectrum. We show the dependence of the QPO properties in a multi-parameter space, and we discuss the implication of our results to the mechanism that produces the QPOs. Our results provide input to the next generation of spectral-timing models, which will help us understand the variability and the environment around the neutron star in these systems.

  13. High resolution time interval counter

    DOEpatents

    Condreva, Kenneth J.

    1994-01-01

    A high resolution counter circuit measures the time interval between the occurrence of an initial and a subsequent electrical pulse to two nanoseconds resolution using an eight megahertz clock. The circuit includes a main counter for receiving electrical pulses and generating a binary word--a measure of the number of eight megahertz clock pulses occurring between the signals. A pair of first and second pulse stretchers receive the signal and generate a pair of output signals whose widths are approximately sixty-four times the time between the receipt of the signals by the respective pulse stretchers and the receipt by the respective pulse stretchers of a second subsequent clock pulse. Output signals are thereafter supplied to a pair of start and stop counters operable to generate a pair of binary output words representative of the measure of the width of the pulses to a resolution of two nanoseconds. Errors associated with the pulse stretchers are corrected by providing calibration data to both stretcher circuits, and recording start and stop counter values. Stretched initial and subsequent signals are combined with autocalibration data and supplied to an arithmetic logic unit to determine the time interval in nanoseconds between the pair of electrical pulses being measured.

  14. High resolution time interval counter

    DOEpatents

    Condreva, K.J.

    1994-07-26

    A high resolution counter circuit measures the time interval between the occurrence of an initial and a subsequent electrical pulse to two nanoseconds resolution using an eight megahertz clock. The circuit includes a main counter for receiving electrical pulses and generating a binary word--a measure of the number of eight megahertz clock pulses occurring between the signals. A pair of first and second pulse stretchers receive the signal and generate a pair of output signals whose widths are approximately sixty-four times the time between the receipt of the signals by the respective pulse stretchers and the receipt by the respective pulse stretchers of a second subsequent clock pulse. Output signals are thereafter supplied to a pair of start and stop counters operable to generate a pair of binary output words representative of the measure of the width of the pulses to a resolution of two nanoseconds. Errors associated with the pulse stretchers are corrected by providing calibration data to both stretcher circuits, and recording start and stop counter values. Stretched initial and subsequent signals are combined with autocalibration data and supplied to an arithmetic logic unit to determine the time interval in nanoseconds between the pair of electrical pulses being measured. 3 figs.

  15. The discovery and modeling of energy dependent time-lags and fractional RMS of heartbeat state in GRS 1915+105

    NASA Astrophysics Data System (ADS)

    Mir, Mubashir; Iqbal, Naseer; Pahari, Mayukh; Misra, Ranjeev

    2016-07-01

    We report the discovery and modeling of enigmatic Energy dependent time-lags and fractional RMS of the heartbeat state in GRS 1915+105. The time-lags reveal the crucial information related to geometry of accretion flow, the emission regions and the relation between various spectral parameters. The lag and frms at the fundamental frequency show non-monotonic behavior with energy. The lag increases up to typically ˜10 keV and later shows a reversal and in some observations becomes hard(negative). However, the lags at the harmonic increase with energy and don't show any turn around at least till ˜20 keV. The frms at harmonic has similar non-monotonic behavior as at fundamental, however the variability amplitude is lesser as expected. The lag seen here can have magnitude of the order of seconds, and thus can't be accounted by light travel time effects or comptonization delays. The continuum X-ray spectra can roughly be described by a disk blackbody and a hard X-ray power-law component and from phase resolved spectroscopy it has been shown that the inner disk radius varies during the oscillation We propose the model based on the delayed response of inner disc (DRIOD) radius to the outer accretion rate i;e r_{in}(t)∝ dot{m}^β (t-τ_d). The fluctuating accretion rate varies the inner disk after a certain time delay t_d which could be of the order of the viscous propagation delays. The model very well explains the observed shape and nature of lags and frms at fundamental and harmonic frequencies. We present here the series of observations that constrain the four free parameters of our model. These parameters contain the vital information related to the nature of accretion flow in a highly periodic state like a heartbeat state.

  16. The High Time Resolution Universe

    NASA Astrophysics Data System (ADS)

    Bailes, Matthew; Possenti, Andrea; Johnston, Simon; Kramer, Michael; Burgay, Marta; Bhat, Ramesh; Keith, Michael; Burke-Spolaor, Sarah; van Straten, Willem; Stappers, Benjamin; Bates, Samuel

    2008-04-01

    The Parkes multibeam surveys heralded a new era in pulsar surveys, more than doubling the number of pulsars known. However, at high time resolution, they were severely limited by the analogue backend system, which limited the volume of sky they could effectively survey to just the local 2-3 kpc. Here we propose to use a new digital backend coupled with Australia's most powerful (16 Tflop) supercomputing cluster to conduct three ambitious surveys for millisecond and relativistic pulsars with the Parkes telescope. We hope to discover over 200 new millisecond and relativistic pulsars that will define the recycled pulsar period distribution, supply pulsars for the timing array and aid in our understanding of binary evolution.

  17. High frequency, high time resolution time-to-digital converter employing passive resonating circuits

    SciTech Connect

    Ripamonti, Giancarlo; Abba, Andrea; Geraci, Angelo

    2010-05-15

    A method for measuring time intervals accurate to the picosecond range is based on phase measurements of oscillating waveforms synchronous with their beginning and/or end. The oscillation is generated by triggering an LC resonant circuit, whose capacitance is precharged. By using high Q resonators and a final active quenching of the oscillation, it is possible to conjugate high time resolution and a small measurement time, which allows a high measurement rate. Methods for fast analysis of the data are considered and discussed with reference to computing resource requirements, speed, and accuracy. Experimental tests show the feasibility of the method and a time accuracy better than 4 ps rms. Methods aimed at further reducing hardware resources are finally discussed.

  18. High frequency, high time resolution time-to-digital converter employing passive resonating circuits.

    PubMed

    Ripamonti, Giancarlo; Abba, Andrea; Geraci, Angelo

    2010-05-01

    A method for measuring time intervals accurate to the picosecond range is based on phase measurements of oscillating waveforms synchronous with their beginning and/or end. The oscillation is generated by triggering an LC resonant circuit, whose capacitance is precharged. By using high Q resonators and a final active quenching of the oscillation, it is possible to conjugate high time resolution and a small measurement time, which allows a high measurement rate. Methods for fast analysis of the data are considered and discussed with reference to computing resource requirements, speed, and accuracy. Experimental tests show the feasibility of the method and a time accuracy better than 4 ps rms. Methods aimed at further reducing hardware resources are finally discussed. PMID:20515164

  19. Remote metrology system (RMS) design concept

    SciTech Connect

    1995-10-19

    A 3D remote metrology system (RMS) is needed to map the interior plasma-facing components of the International Thermonuclear Experimental Reactor (ITER). The performance and survival of these components within the reactor vessel are strongly dependent on their precise alignment and positioning with respect to the plasma edge. Without proper positioning and alignment, plasma-facing surfaces will erode rapidly. A RMS design involving Coleman Research Corporation (CRC) fiber optic coherent laser radar (CLR) technology is examined in this study. The fiber optic CLR approach was selected because its high precision should be able to meet the ITER 0.1 mm accuracy requirement and because the CLR`s fiber optic implementation allows a 3D scanner to operate remotely from the RMS system`s vulnerable components. This design study has largely verified that a fiber optic CLR based RMS can survive the ITER environment and map the ITER interior at the required accuracy at a one measurement/cm{sup 2} density with a total measurement time of less than one hour from each of six or more vertically deployed measurement probes. The design approach employs a sealed and pressurized measurement probe which is attached with an umbilical spiral bellows conduit. This conduit bears fiber optic and electronic links plus a stream of air to lower the temperature in the interior of the probe. Lowering the probe temperature is desirable because probe electromechanical components which could survive the radiation environment often were not rated for the 200 C temperature. The tip of the probe whose outer shell has a flexible bellows joint can swivel in two degrees of freedom to allow mapping operations at each probe deployment level. This design study has concluded that the most successful scanner design will involve a hybrid AO beam deflector and mechanical scanner.

  20. A time digitizer CMOS gate-array with a 250 ps time resolution

    SciTech Connect

    Arai, Yasuo

    1996-02-01

    Recent high-energy physics experiments are demanding a pipeline (deadtime-less) time-to-digital converter (TDC) with a time resolution of better than 500 ps and a double-pulse resolution of less than 30 ns. The TDC must keep all of the timing history until a trigger signal arrives about 3 {micro}s later. In large experiments, since the number of channels used is more than 100 k, the device must have a low power dissipation, a high circuit density and a low cost. A pipelined time digitizer CMOS gate-array has been developed using 0.5 {micro}m Sea-of-Gate technology. Precise timing signals which are used to sample input signals are generated from 32 taps of an asymmetric ring oscillator. The frequency of the oscillator is controlled by a phase-locked loop (PLL) circuit which runs in the 10--50 MHz frequency range. A test chip has been developed and tested; a time resolution of 250 ps rms at 40 MHz clock was measured. The chip has 4 channels and encoding circuits for both the rising and the falling edges of the input signals. The chip has 128-word dual-port memories, allowing the histories of the input signals to be stored and causing no deadtime for the conversion.

  1. A method for coincidence timing resolution enhancement

    NASA Astrophysics Data System (ADS)

    Ermis, E. E.; Celiktas, C.; Pilicer, E.

    2016-05-01

    A method including the coincidence time resolution improvement for a TOF/positron emission tomography system was suggested. The spectrometer for this aim was composed of two NaI(Tl) and two plastic scintillation detectors. Experimental results were supported by FLUKA Monte Carlo simulation program by constructing the detector setup in software medium. Present experimental results verified our previous results and conclusions obtained from the suggested method. It was concluded that better resolutions would help the improvement not only on the TOF gain but also on the spatial resolution, leading to better images and helping the Physician in his/her diagnosis and treatment.

  2. A modified commercial Ti:sapphire laser with 4 kHz rms linewidth

    NASA Astrophysics Data System (ADS)

    Haubrich, D.; Wynands, R.

    1996-02-01

    We have modified a commercial Ti:sapphire laser to allow optical phase stabilization to an extremely stable semiconductor laser, which in turn is locked to a Doppler-free resonance in a cesium vapor cell. For time scales from 10 μs up to several hours the combined system has a rms linewidth of 4 kHz with respect to the cesium resonance. The system allows the resolution of extremely narrow resonances in a cloud of trapped atoms.

  3. Incorporating Skew into RMS Surface Roughness Probability Distribution

    NASA Technical Reports Server (NTRS)

    Stahl, Mark T.; Stahl, H. Philip.

    2013-01-01

    The standard treatment of RMS surface roughness data is the application of a Gaussian probability distribution. This handling of surface roughness ignores the skew present in the surface and overestimates the most probable RMS of the surface, the mode. Using experimental data we confirm the Gaussian distribution overestimates the mode and application of an asymmetric distribution provides a better fit. Implementing the proposed asymmetric distribution into the optical manufacturing process would reduce the polishing time required to meet surface roughness specifications.

  4. The TDCpix readout ASIC: A 75 ps resolution timing front-end for the NA62 Gigatracker hybrid pixel detector

    NASA Astrophysics Data System (ADS)

    Kluge, A.; Aglieri Rinella, G.; Bonacini, S.; Jarron, P.; Kaplon, J.; Morel, M.; Noy, M.; Perktold, L.; Poltorak, K.

    2013-12-01

    The TDCpix is a novel pixel readout ASIC for the NA62 Gigatracker detector. NA62 is a new experiment being installed at the CERN Super Proton Synchrotron. Its Gigatracker detector shall provide on-beam tracking and time stamping of individual particles with a time resolution of 150 ps rms. It will consist of three tracking stations, each with one hybrid pixel sensor. The peak flow of particles crossing the detector modules reaches 1.27 MHz/mm2 for a total rate of about 0.75 GHz. Ten TDCpix chips will be bump-bonded to every silicon pixel sensor. Each chip shall perform time stamping of 100 M particle hits per second with a detection efficiency above 99% and a timing accuracy better than 200 ps rms for an overall three-station-setup time resolution of better than 150 ps. The TDCpix chip has been designed in a 130 nm CMOS technology. It will feature 45×40 square pixels of 300×300 μm2 and a complex End of Column peripheral region including an array of TDCs based on DLLs, four high speed serializers, a low-jitter PLL, readout and control circuits. This contribution will describe the complete design of the final TDCpix ASIC. It will discuss design choices, the challenges faced and some of the lessons learned. Furthermore, experimental results from the testing of circuit prototypes will be presented. These demonstrate the achievement of key performance figures such as a time resolution of the processing chain of 75 ps rms with a laser sent to the center of the pixel and the capability of time stamping charged particles with an overall resolution below 200 ps rms.

  5. 10 microsecond time resolution studies of Cygnus X-1

    SciTech Connect

    Wen, H.C.

    1997-06-01

    Time variability analyses have been applied to data composed of event times of X-rays emitted from the binary system Cygnus X-1 to search for unique black hole signatures. The X-ray data analyzed was collected at ten microsecond time resolution or better from two instruments, the High Energy Astrophysical Observatory (HEAO) A-1 detector and the Rossi X-ray Timing Explorer (XTE) Proportional Counter Array (PCA). HEAO A-1 and RXTE/PCA collected data from 1977--79 and from 1996 on with energy sensitivity from 1--25 keV and 2--60 keV, respectively. Variability characteristics predicted by various models of an accretion disk around a black hole have been searched for in the data. Drop-offs or quasi-periodic oscillations (QPOs) in the Fourier power spectra are expected from some of these models. The Fourier spectral technique was applied to the HEAO A-1 and RXTE/PCA data with careful consideration given for correcting the Poisson noise floor for instrumental effects. Evidence for a drop-off may be interpreted from the faster fall off in variability at frequencies greater than the observed breaks. Both breaks occur within the range of Keplerian frequencies associated with the inner edge radii of advection-dominated accretion disks predicted for Cyg X-1. The break between 10--20 Hz is also near the sharp rollover predicted by Nowak and Wagoner`s model of accretion disk turbulence. No QPOs were observed in the data for quality factors Q > 9 with a 95% confidence level upper limit for the fractional rms amplitude at 1.2% for a 16 M{sub {circle_dot}} black hole.

  6. Time resolution of a scintillating fiber detector

    NASA Astrophysics Data System (ADS)

    Horikawa, S.; Toeda, T.; Daito, I.; Doushita, N.; Hasegawa, T.; Horikawa, N.; Iwata, T.; Kibe, Y.; Matsuda, T.; Miyachi, Y.; Noboriguchi, K.; Takabayashi, N.; Tohyama, T.; Wakai, A.

    1999-07-01

    The performance of scintillating fiber detectors with 2 m long light guides was investigated for COMPASS experiment, using a 450 MeV/ c electron beam.Prototypes consisting of 0.5 mm diameter fibers (Kuraray SCSF-38 single-cladding) with the position-sensitive photomultipliers H6568 (Hamamatsu) were constructed for the test. The time resolution of σ˜430 ps was obtained with about 10 photoelectrons for the prototype of 10-layers structure.

  7. DSCOVR High Time Resolution Solar Wind Measurements

    NASA Technical Reports Server (NTRS)

    Szabo, Adam

    2012-01-01

    The Deep Space Climate Observatory (DSCOVR), previously known as Triana, spacecraft is expected to be launched in late 2014. It will carry a fluxgate magnetometer, Faraday Cup solar wind detector and a top-hat electron electrostatic analyzer. The Faraday Cup will provide an unprecedented 10 vectors/sec time resolution measurement of the solar wind proton and alpha reduced distribution functions. Coupled with the 40 vector/sec vector magnetometer measurements, the identification of specific wave modes in the solar wind will be possible for the first time. The science objectives and data products of the mission will be discussed.

  8. Branching in Pea (Action of Genes Rms3 and Rms4).

    PubMed Central

    Beveridge, C. A.; Ross, J. J.; Murfet, I. C.

    1996-01-01

    The nonallelic ramosus mutations rms3-2 and rms4 of pea (Pisum sativum L.) cause extensive release of vegetative axillary buds and lateral growth in comparison with wild-type (cv Torsdag) plants, in which axillary buds are not normally released under the conditions utilized. Grafting studies showed that the expression of the rms4 mutation in the shoot is independent of the genotype of the root-stock. In contrast, the length of the branches at certain nodes of rms3-2 plants was reduced by grafting to wild-type stocks, indicating that the wild-type Rms3 gene may control the level of a mobile substance produced in the root. This substance also appears to be produced in the shoot because Rms3 shoots did not branch when grafted to mutant rms3-2 rootstocks. However, the end product of the Rms3 gene appears to differ from that of the Rms2 gene (C.A. Beveridge, J.J. Ross, and I.C. Murfet [1994] Plant Physiol 104: 953-959) because reciprocal grafts between rms3-2 and rms2 seedlings produced mature shoots with apical dominance similar to that of rms3-2 and rms2 shoots grafted to wild-type stocks. Indole-3-acetic acid levels were not reduced in apical or nodal portions of rms4 plants and were actually elevated (up to 2-fold) in rms3-2 plants. It is suggested that further studies with these branching mutants may enable significant progress in understanding the normal control of apical dominance and the related communication between the root and shoot. PMID:12226224

  9. Advances in coincidence time resolution for PET.

    PubMed

    Cates, Joshua W; Levin, Craig S

    2016-03-21

    Coincidence time resolution (CTR), an important parameter for time-of-flight (TOF) PET performance, is determined mainly by properties of the scintillation crystal and photodetector used. Stable production techniques for LGSO:Ce (Lu1.8Gd0.2SiO5:Ce) with decay times varying from ∼ 30-40 ns have been established over the past decade, and the decay time can be accurately controlled with varying cerium concentration (0.025-0.075 mol%). This material is promising for TOF-PET, as it has similar light output and equivalent stopping power for 511 keV annihilation photons compared to industry standard LSO:Ce and LYSO:Ce, and the decay time is improved by more than 30% with proper Ce concentration. This work investigates the achievable CTR with LGSO:Ce (0.025 mol%) when coupled to new silicon photomultipliers. Crystal element dimension is another important parameter for achieving fast timing. 20 mm length crystal elements achieve higher 511 keV photon detection efficiency, but also introduce higher scintillation photon transit time variance. 3 mm length crystals are not practical for PET, but have reduced scintillation transit time spread. The CTR between pairs of 2.9 × 2.9 × 3 mm(3) and 2.9 × 2.9 × 20 mm(3) LGSO:Ce crystals was measured to be 80 ± 4 and 122 ± 4 ps FWHM, respectively. Measurements of light yield and intrinsic decay time are also presented for a thorough investigation into the timing performance with LGSO:Ce (0.025 mol%). PMID:26914187

  10. Femtosecond resolution timing jitter correction on a TW scale Ti:sapphire laser system for FEL pump-probe experiments

    NASA Astrophysics Data System (ADS)

    Csatari Divall, Marta; Mutter, Patrick; Divall, Edwin J.; Hauri, Christoph P.

    2015-11-01

    Intense ultrashort pulse lasers are used for fs resolution pumpprobe experiments more and more at large scale facilities, such as free electron lasers (FEL). Measurement of the arrival time of the laser pulses and stabilization to the machine or other sub-systems on the target, is crucial for high time-resolution measurements. In this work we report on a single shot, spectrally resolved, non-collinear cross-correlator with sub-fs resolution. With a feedback applied we keep the output of the TW class Ti:sapphire amplifier chain in time with the seed oscillator to ~3 fs RMS level for several hours. This is well below the typical pulse duration used at FELs and supports fs resolution pump-probe experiments. Short term jitter and long term timing drift measurements are presented. Applicability to other wavelengths and integration into the timing infrastructure of the FEL are also covered to show the full potential of the device.

  11. Simulation studies of emittance growth in RMS mismatched beams

    SciTech Connect

    Cucchetti, A.; Wangler, T. ); Reiser, M. )

    1991-01-01

    As shown in a separate paper, a charged-particle beam, whose rms size is not matched when injected into a transport channel or accelerator, has excess energy compared with that of a matched beam. If nonlinear space-charge forces are present and the mismatched beam transforms to a matched equilibrium state, rms-emittance growth will occur. The theory yields formulas for the possible rms-emittance growth, but not for the time it takes to achieve this growth. In this paper we present the results of systematic simulation studies for a mismatched 2-D round beam in an ideal transport channel with continuous linear focusing. Emittance growth rates obtained from the simulations for different amounts of mismatch and initial charge will be presented and the emittance growth will be compared with the theory. 6 refs., 7 figs.

  12. The High Time Resolution Radio Sky

    NASA Astrophysics Data System (ADS)

    Thornton, D.

    2013-11-01

    Pulsars are laboratories for extreme physics unachievable on Earth. As individual sources and possible orbital companions can be used to study magnetospheric, emission, and superfluid physics, general relativistic effects, and stellar and binary evolution. As populations they exhibit a wide range of sub-types, with parameters varying by many orders of magnitude signifying fundamental differences in their evolutionary history and potential uses. There are currently around 2200 known pulsars in the Milky Way, the Magellanic clouds, and globular clusters, most of which have been discovered with radio survey observations. These observations, as well as being suitable for detecting the repeating signals from pulsars, are well suited for identifying other transient astronomical radio bursts that last just a few milliseconds that either singular in nature, or rarely repeating. Prior to the work of this thesis non-repeating radio transients at extragalactic distances had possibly been discovered, however with just one example status a real astronomical sources was in doubt. Finding more of these sources was a vital to proving they were real and to open up the universe for millisecond-duration radio astronomy. The High Time Resolution Universe survey uses the multibeam receiver on the 64-m Parkes radio telescope to search the whole visible sky for pulsars and transients. The temporal and spectral resolution of the receiver and the digital back-end enable the detection of relatively faint, and distant radio sources. From the Parkes telescope a large portion of the Galactic plane can be seen, a rich hunting ground for radio pulsars of all types, while previously poorly surveyed regions away from the Galactic plane are also covered. I have made a number of pulsar discoveries in the survey, including some rare systems. These include PSR J1226-6208, a possible double neutron star system in a remarkably circular orbit, PSR J1431-471 which is being eclipsed by its companion with

  13. Extratropical transitioning in the RMS Japan typhoon wind field model

    NASA Astrophysics Data System (ADS)

    Loridan, Thomas; Scherer, Emilie; Khare, Shree

    2013-04-01

    Given its meridional extent and location within the Pacific basin, Japan is regularly impacted by strong winds from cyclones at different stages of their lifecycle. To quantify the associated risk of damage to properties, catastrophe models such as the ones developed by RMS aim to simulate wind fields from thousands of stochastic storms that extrapolate historical events. In a recent study using 25 years of reanalysis data, Kitabatake (2011) estimated that 40 % of all Pacific tropical cyclones completed their transition as an extra tropical system. From a cat modelling point of view it is the increase in wind field asymmetry observed during these transitioning episodes that is critical, with examples like typhoon Tokage in 2004 showing the potential for damaging gusts on both sides of the storm track. In this context a compromise has to be found between the need for complex numerical models able to simulate wind field variability around the cyclone during its entire evolution, and obvious running time constrains. The RMS wind field model is based on an optimized version of the Willoughby parametric profile (Willoughby et al., 2006) which requires calibration against targets representative of cyclone wind fields throughout their lifecycle. We here present the different sources of data involved in the development of this model. This includes (1) satellite products to characterize wind fields from fully tropical storms, (2) high resolution simulations of key transitioning events using the WRF mesoscale model to complement the database at other stages (i.e. for transitioning and fully extra tropical wind fields), and (3) reanalysis data which can be used with Hart (2003)'s cyclone phase space methodology to provide an estimate of the mean duration of transitioning episodes in the Pacific. Kitabatake, N., 2011: Climatology of extratropical transition of tropical cyclones in the Western North Pacific defined by using cyclone phase space. J. Meteor. Soc. Japan, 89, 309

  14. Quality control of the RMS US flood model

    NASA Astrophysics Data System (ADS)

    Jankowfsky, Sonja; Hilberts, Arno; Mortgat, Chris; Li, Shuangcai; Rafique, Farhat; Rajesh, Edida; Xu, Na; Mei, Yi; Tillmanns, Stephan; Yang, Yang; Tian, Ye; Mathur, Prince; Kulkarni, Anand; Kumaresh, Bharadwaj Anna; Chaudhuri, Chiranjib; Saini, Vishal

    2016-04-01

    The RMS US flood model predicts the flood risk in the US with a 30 m resolution for different return periods. The model is designed for the insurance industry to estimate the cost of flood risk for a given location. Different statistical, hydrological and hydraulic models are combined to develop the flood maps for different return periods. A rainfall-runoff and routing model, calibrated with observed discharge data, is run with 10 000 years of stochastic simulated precipitation to create time series of discharge and surface runoff. The 100, 250 and 500 year events are extracted from these time series as forcing for a two-dimensional pluvial and fluvial inundation model. The coupling of all the different models which are run on the large area of the US implies a certain amount of uncertainty. Therefore, special attention is paid to the final quality control of the flood maps. First of all, a thorough quality analysis of the Digital Terrain model and the river network was done, as the final quality of the flood maps depends heavily on the DTM quality. Secondly, the simulated 100 year discharge in the major river network (600 000 km) is compared to the 100 year discharge derived using extreme value distribution of all USGS gauges with more than 20 years of peak values (around 11 000 gauges). Thirdly, for each gauge the modelled flood depth is compared to the depth derived from the USGS rating curves. Fourthly, the modelled flood depth is compared to the base flood elevation given in the FEMA flood maps. Fifthly, the flood extent is compared to the FEMA flood extent. Then, for historic events we compare flood extents and flood depths at given locations. Finally, all the data and spatial layers are uploaded on geoserver to facilitate the manual investigation of outliers. The feedback from the quality control is used to improve the model and estimate its uncertainty.

  15. The time resolution of the St Petersburg paradox

    PubMed Central

    Peters, Ole

    2011-01-01

    A resolution of the St Petersburg paradox is presented. In contrast to the standard resolution, utility is not required. Instead, the time-average performance of the lottery is computed. The final result can be phrased mathematically identically to Daniel Bernoulli's resolution, which uses logarithmic utility, but is derived using a conceptually different argument. The advantage of the time resolution is the elimination of arbitrary utility functions. PMID:22042904

  16. The rms-flux relations in different branches in Cyg X-2

    NASA Astrophysics Data System (ADS)

    Li, Z. B.; Song, L. M.; Qu, J. L.; Lei, Y. J.; Nie, J. Y.; Zhang, C. M.

    2012-10-01

    In this paper, the rms-flux (root mean square-flux) relation along the Z-track of the bright Z-Source Cyg X-2 is analyzed using the observational data of Rossi X-ray Timing Explorer (RXTE). Three types of rms-flux relations, i.e. positive, negative, and `arch'-like correlations are found in different branches. The rms is positively correlated with flux in normal branch (NB), but anti-correlated in the vertical horizontal branch (VHB). The rms-flux relation shows an `arch'-like shape in the horizontal branch (HB). We also try to explain this phenomenon using existing models.

  17. A method for generating high resolution satellite image time series

    NASA Astrophysics Data System (ADS)

    Guo, Tao

    2014-10-01

    There is an increasing demand for satellite remote sensing data with both high spatial and temporal resolution in many applications. But it still is a challenge to simultaneously improve spatial resolution and temporal frequency due to the technical limits of current satellite observation systems. To this end, much R&D efforts have been ongoing for years and lead to some successes roughly in two aspects, one includes super resolution, pan-sharpen etc. methods which can effectively enhance the spatial resolution and generate good visual effects, but hardly preserve spectral signatures and result in inadequate analytical value, on the other hand, time interpolation is a straight forward method to increase temporal frequency, however it increase little informative contents in fact. In this paper we presented a novel method to simulate high resolution time series data by combing low resolution time series data and a very small number of high resolution data only. Our method starts with a pair of high and low resolution data set, and then a spatial registration is done by introducing LDA model to map high and low resolution pixels correspondingly. Afterwards, temporal change information is captured through a comparison of low resolution time series data, and then projected onto the high resolution data plane and assigned to each high resolution pixel according to the predefined temporal change patterns of each type of ground objects. Finally the simulated high resolution data is generated. A preliminary experiment shows that our method can simulate a high resolution data with a reasonable accuracy. The contribution of our method is to enable timely monitoring of temporal changes through analysis of time sequence of low resolution images only, and usage of costly high resolution data can be reduces as much as possible, and it presents a highly effective way to build up an economically operational monitoring solution for agriculture, forest, land use investigation

  18. The resupply interface mechanism RMS compatibility test

    NASA Technical Reports Server (NTRS)

    Jackson, Stewart W.; Gallo, Frank G.

    1990-01-01

    Spacecraft on-orbit servicing consists of exchanging components such as payloads, orbital replacement units (ORUs), and consumables. To accomplish the exchange of consumables, the receiving vehicle must mate to the supplier vehicle. Mating can be accomplished by a variety of docking procedures. However, these docking schemes are mission dependent and can vary from shuttle bay berthing to autonomous rendezvous and docking. Satisfying the many docking conditions will require use of an innovative docking device. The device must provide fluid, electrical, pneumatic and data transfer between vehicles. Also, the proper stiffness must be obtained and sustained between the vehicles. A device to accomplish this, the resupply interface mechanism (RIM), was developed. The RIM is a unique device because it grasps the mating vehicle, draws the two vehicles together, simultaneously mates all connectors, and rigidizes the mating devices. The NASA-Johnson Manipulator Development Facility was used to study how compatible the RIM is to on orbit docking and berthing. The facility contains a shuttle cargo bay mockup with a remote manipulator system (RMS). This RMS is used to prepare crew members for shuttle missions involving spacecraft berthing operations. The MDF proved to be an excellant system for testing the RIM/RMS compatibility. The elements examined during the RIM JSC test were: RIM gross and fine alignment; berthing method sequence; visual cuing aids; utility connections; and RIM overall performance. The results showed that the RIM is a good device for spacecraft berthing operations. Mating was accomplished during every test run and all test operators (crew members) felt that the RIM is an effective device. The purpose of the JSC RIM test and its results are discussed.

  19. High time-resolution photodetectors for PET applications

    SciTech Connect

    Ronzhin, Anatoly

    2015-11-27

    This paper describes recent developments aiming at the improvement of the time resolution of photodetectors used in positron emission tomography (PET). Promising photodetector candidates for future PET-time-of-flight (TOF) applications are also discussed.

  20. High time-resolution photodetectors for PET applications

    DOE PAGESBeta

    Ronzhin, Anatoly

    2016-02-01

    This paper describes recent developments aiming at the improvement of the time resolution of photodetectors used in positron emission tomography (PET). Promising photodetector candidates for future PET-time-of-flight (TOF) applications are also discussed.

  1. The TDCpix Readout ASIC: A 75 ps Resolution Timing Front-End for the Gigatrackerof theNA62 Experiment

    NASA Astrophysics Data System (ADS)

    Rinella, G. Aglieri; Fiorini, M.; Jarron, P.; Kaplon, J.; Kluge, A.; Martin, E.; Morel, M.; Noy, M.; Perktold, L.; Poltorak, K.

    NA62 is an experiment under development at the CERN Super Proton Synchrotron, aiming at measuring ultra rare kaon decays. The Gigatracker (GTK) detector shall combine on-beam tracking of individual particles with a time resolution of 150 ps rms. The peak flow of particles crossing the detector modules reaches 1.27 MHz/mm2 fora total rateof about 0.75 GHz.Ahybrid siliconpixel detectoris beingdevelopedto meet these requirements. The pixel chip for the Gigatracker (TDCpix) is under design. The TDCpix chip will feature 1800 square pixels of 300×300 μm2 arranged in a matrix of 45 rows × 40 columns. Bump-bonded to a silicon pixel sensor it shall perform time stamping of particle hits with a timing accuracybetter than 200 ps rms and a detection efficiencyabove 99%. The chosen architecture provides full separation of the sensitive analog amplifiers of the pixel matrix from the noisy digital circuits of the TDCs and of the readout blocks. Discriminated hit signals from each pixel are transmitted to the end of column region. An array ofTime to Digital Converters (TDC) is implemented at the bottom of the pixel array. The TDCs are based on time tagging the events with the fine time codes generated by Delay Locked Loops (DLL) and have a nominal time bin of ˜100 ps. Time stamps and time-over-threshold are recorded for each discriminated hit and the correction of the discriminator's time-walk is performed off-detector. Data are continuously transmitted on four 2.4 Gb/s serial output links. Adescription of the on-going design of the final TDCpix is given in this paper. Design choices and some technical implementation details are presented. Aprototype ASIC including thekeycomponents of this architecture has been manufactured. The achievement of specification figures such as a time resolution of the processing chain of 75 ps rms as well as charged particle time stampingwitha resolutionbetterthan200psrmswere demonstratedexperimentally.Asummaryoftheseresultsisalso presented in

  2. High resolution distributed time-to-digital converter (TDC) in a White Rabbit network

    NASA Astrophysics Data System (ADS)

    Pan, Weibin; Gong, Guanghua; Du, Qiang; Li, Hongming; Li, Jianmin

    2014-02-01

    The Large High Altitude Air Shower Observatory (LHAASO) project consists of a complex detector array with over 6000 detector nodes spreading over 1.2 km2 areas. The arrival times of shower particles are captured by time-to-digital converters (TDCs) in the detectors' frontend electronics, the arrival direction of the high energy cosmic ray are then to be reconstructed from the space-time information of all detector nodes. To guarantee the angular resolution of 0.5°, a time synchronization of 500 ps (RMS) accuracy and 100 ps precision must be achieved among all TDC nodes. A technology enhancing Gigabit Ethernet, called the White Rabbit (WR), has shown the capability of delivering sub-nanosecond accuracy and picoseconds precision of synchronization over the standard data packet transfer. In this paper we demonstrate a distributed TDC prototype system combining the FPGA based TDC and the WR technology. With the time synchronization and data transfer services from a compact WR node, separate FPGA-TDC nodes can be combined to provide uniform time measurement information for correlated events. The design detail and test performance will be described in the paper.

  3. Prospects for Electron Imaging with Ultrafast Time Resolution

    SciTech Connect

    Armstrong, M R; Reed, B W; Torralva, B R; Browning, N D

    2007-01-26

    Many pivotal aspects of material science, biomechanics, and chemistry would benefit from nanometer imaging with ultrafast time resolution. Here we demonstrate the feasibility of short-pulse electron imaging with t10 nanometer/10 picosecond spatio-temporal resolution, sufficient to characterize phenomena that propagate at the speed of sound in materials (1-10 kilometer/second) without smearing. We outline resolution-degrading effects that occur at high current density followed by strategies to mitigate these effects. Finally, we present a model electron imaging system that achieves 10 nanometer/10 picosecond spatio-temporal resolution.

  4. Hardware interface unit for control of shuttle RMS vibrations

    NASA Technical Reports Server (NTRS)

    Lindsay, Thomas S.; Hansen, Joseph M.; Manouchehri, Davoud; Forouhar, Kamran

    1994-01-01

    Vibration of the Shuttle Remote Manipulator System (RMS) increases the time for task completion and reduces task safety for manipulator-assisted operations. If the dynamics of the manipulator and the payload can be physically isolated, performance should improve. Rockwell has developed a self contained hardware unit which interfaces between a manipulator arm and payload. The End Point Control Unit (EPCU) is built and is being tested at Rockwell and at the Langley/Marshall Coupled, Multibody Spacecraft Control Research Facility in NASA's Marshall Space Flight Center in Huntsville, Alabama.

  5. A high-resolution time-to-digital converter using a three-level resolution

    NASA Astrophysics Data System (ADS)

    Dehghani, Asma; Saneei, Mohsen; Mahani, Ali

    2016-08-01

    In this article, a three-level resolution Vernier delay line time-to-digital converter (TDC) was proposed. The proposed TDC core was based on the pseudo-differential digital architecture that made it insensitive to nMOS and pMOS transistor mismatches. It also employed a Vernier delay line (VDL) in conjunction with an asynchronous read-out circuitry. The time interval resolution was equal to the difference of delay between buffers of upper and lower chains. Then, via the extra chain included in the lower delay line, resolution was controlled and power consumption was reduced. This method led to high resolution and low power consumption. The measurement results of TDC showed a resolution of 4.5 ps, 12-bit output dynamic range, and integral nonlinearity of 1.5 least significant bits. This TDC achieved the consumption of 68.43 µW from 1.1-V supply.

  6. Timing resolution measurements of a 3 in. lanthanum bromide detector

    NASA Astrophysics Data System (ADS)

    Galli, L.; De Gerone, M.; Dussoni, S.; Nicolò, D.; Papa, A.; Tenchini, F.; Signorelli, G.

    2013-08-01

    Cerium-doped lanthanum bromide (LaBr3:Ce) is a scintillator that presents very good energy and timing resolutions and it is a perfect candidate for photon detector in future experiments to search for lepton flavor violation as in μ → eγ or μ → e conversion. While energy resolution was thoroughly investigated, timing resolution at several MeV presents some experimental challenge. We measured the timing resolution of a 3 in.×3 in. cylindrical LaBr3(Ce) crystal versus few reference detectors by means of a nuclear reaction from a Cockcroft-Walton accelerator that produces coincident γ-rays in the 4.4-11.6 MeV range. Preliminary results allow us to extrapolate the properties of a segmented γ-ray detector in the 50-100 MeV range.

  7. Recipes for high resolution time-of-flight detectors

    SciTech Connect

    Anz, S.J. |; Felter, T.E.; Hess, B.V.; Daley, R.S.; Roberts, M.L.; Williams, R.S.

    1995-01-01

    The authors discuss the dynamics, construction, implementation and benefits of a time-of-flight (TOF) detector with count rates an order of magnitude higher and resolution three to four times better than that obtainable with a surface barrier detector. The propose use of design criteria for a time-of-flight detector is outlined, and the determination of a TOF detector`s total relative timing error and how this value determines the mass resolution are illustrated using a graphical analysis. They present simulation and experimental examples employing light ions and discuss advantages and pitfalls of medium-energy heavy ion TOF spectrometry.

  8. 400-ps time resolution with a passively quenched avalanche photodiode.

    PubMed

    Grayson, T P; Wang, L J

    1993-06-01

    Avalanche photodiodes (APD's) operated in a single-photon-counting Geiger mode are becoming attractive alternatives to photomultiplier tubes for low-light-level detection and signal timing. By paying careful attention to the design and construction of a simple APD passive quenching circuit to reduce stray capacitances, we directly measured a time resolution of 410 ps FWHM for a commercial APD. A more detailed data analysis shows the actual time resolution to be ~ 390 ps FWHM. This is believed to be the most accurate time response for such a simple, inexpensive, and widely available device achieved to date. PMID:20829894

  9. Dynamic imaging reveals that BDNF can independently regulate motility and direction of RMS neuroblast migration

    PubMed Central

    Bagley, Joshua A.; Belluscio, Leonardo

    2010-01-01

    Neuronal precursors generated in the subventricular zone (SVZ) migrate through the rostral migratory stream (RMS) to the olfactory bulb (OB). Although, the mechanisms regulating this migration remain largely unknown, studies have suggested that molecular factors, such as Brain-Derived Neurotrophic Factor (BDNF) emanating from the OB, may function as chemoattractants drawing neuroblasts toward their target. To better understand the role of BDNF in RMS migration, we used an acute slice preparation from early postnatal mice to track the tangential migration of GAD65-GFP labeled RMS neuroblasts with confocal time-lapse imaging. By quantifying the cell dynamics using specific directional and motility criteria, our results showed that removal of the OB did not alter the overall directional trajectory of neuroblasts, but did reduce their motility. This suggested that additional guidance factors may be present locally within the RMS. Thus, we next demonstrated that BDNF and its high affinity receptor, TrkB, are indeed heterogeneously expressed within the RMS at postnatal day 7, and by altering BDNF levels within the entire pathway, showed that reduced BDNF signaling changes both neuroblast motility and direction, while increased BDNF levels changes only motility. Together these data reveal that during this early postnatal period BDNF plays a complex role in regulating both the motility and direction of RMS flow, and that it arises from within the RMS itself, as well as from the olfactory bulb. PMID:20538046

  10. Femtosecond resolution timing jitter correction on a TW scale Ti:sapphire laser system for FEL pump-probe experiments.

    PubMed

    Csatari Divall, Marta; Mutter, Patrick; Divall, Edwin J; Hauri, Christoph P

    2015-11-16

    Intense ultrashort pulse lasers are used for fs resolution pump-probe experiments more and more at large scale facilities, such as free electron lasers (FEL). Measurement of the arrival time of the laser pulses and stabilization to the machine or other sub-systems on the target, is crucial for high time-resolution measurements. In this work we report on a single shot, spectrally resolved, non-collinear cross-correlator with sub-fs resolution. With a feedback applied we keep the output of the TW class Ti:sapphire amplifier chain in time with the seed oscillator to ~3 fs RMS level for several hours. This is well below the typical pulse duration used at FELs and supports fs resolution pump-probe experiments. Short term jitter and long term timing drift measurements are presented. Applicability to other wavelengths and integration into the timing infrastructure of the FEL are also covered to show the full potential of the device. PMID:26698475

  11. High-resolution signal synthesis for time-frequency distributions

    SciTech Connect

    Cunningham, G.S.; Williams, W.J.

    1993-03-01

    Bilinear time-frequency distributions (TFDs) offer improved resolution over linear nine-frequency representations (TFRs), but many TFDs are costly to evaluate and are not associated with signal synthesis algorithms. Recently, the spectrogram (SP) decomposition and weighted reversal correlator decomposition have been used to define low-cost, high-resolution TFDs. In this paper, we show that the vector-valued ``square-root`` of a TFD (VVTFR) provides a representational underpinning for the TFD. By synthesizing signals from modified VVTFRs, we define high-resolution signal synthesis algorithms associated with TFDs. The signal analysis and synthesis packages can be implemented as weighted sums of SP/short-time Fourier Transform signal analysis and synthesis packages, which are widely available, allowing the interested non-specialist easy access to high-resolution methods.

  12. High-resolution signal synthesis for time-frequency distributions

    SciTech Connect

    Cunningham, G.S. ); Williams, W.J. . Dept. of Electrical Engineering and Computer Science)

    1993-01-01

    Bilinear time-frequency distributions (TFDs) offer improved resolution over linear nine-frequency representations (TFRs), but many TFDs are costly to evaluate and are not associated with signal synthesis algorithms. Recently, the spectrogram (SP) decomposition and weighted reversal correlator decomposition have been used to define low-cost, high-resolution TFDs. In this paper, we show that the vector-valued square-root'' of a TFD (VVTFR) provides a representational underpinning for the TFD. By synthesizing signals from modified VVTFRs, we define high-resolution signal synthesis algorithms associated with TFDs. The signal analysis and synthesis packages can be implemented as weighted sums of SP/short-time Fourier Transform signal analysis and synthesis packages, which are widely available, allowing the interested non-specialist easy access to high-resolution methods.

  13. 4 channel, 20 ps resolution, monolithic time-to-amplitude converter for multichannel TCSPC systems

    NASA Astrophysics Data System (ADS)

    Crotti, Matteo; Rech, Ivan; Labanca, Ivan; Ghioni, Massimo

    2012-06-01

    Over the past years an always growing interest has arisen about the measurement technique of time-correlated single photon counting (TCSPC) and many applications exploiting TCSPC have been developing in several fields, such as medicine and chemistry. The use of multianode PMTs and of single photon avalanche diode arrays led to the development of acquisition systems with several parallel channels, to employ the TCSPC technique in even more applications. Since TCSPC basically consists in the photons arrival time measurement, the most important part of an acquisition chain is the time measurement block, which must have high resolution and low differential nonlinearity and, in order to implement multidimensional systems, it has to be integrated to reduce both cost and area. To accomplish all these specifications, we have designed and fabricated a 4 channel fully integrated time-to-amplitude converter (TAC), built in 0.35 μm Si-Ge technology, characterized by a variable full scale range from 11 ns to 89 ns, very good time resolution (better than 20 ps FWHM), low differential nonlinearity (better than 0.04 LSB peak-peak and less than 0.2% LSB rms), high counting rate (16 MHz), low and constant power dissipation (50 mW) and low area occupation (340 × 390 μm2 per channel). Our measurements also show a very little crosstalk between converters integrated on the same chip; this feature together with low power and low area make the fabricated converter suitable for parallelization, so that it can be the starting point for future acquisition chains with a high number of parallel channels.

  14. RMS / PFTA operations using grapple fixture number (no.) 5

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Remote manipulator system (RMS) end effector grapples the bar-bell shaped Payload Flight Test Article (PFTA) using grapple fixture number (no.) 5 on forward screen support structure for dynamic interaction tests including: Single and Manual Control System Evaluation; RMS / Primary Reaction Control System (PRCS) Interaction Tests; Single Joint Control System Evaluation; and Manual Augmented Control Evaluation. Views look down RMS upper arm boom to end effector with elbow pitch joint, elbow closed circuit television (CCTV) camera, wrist joint, and wrist CCTV visible in between. PFTA and RMS stand out brillantly against the darkness of space.

  15. Transmission mode time-reversal super-resolution imaging.

    PubMed

    Lehman, Sean K; Devaney, Anthony J

    2003-05-01

    The theory of time-reversal super-resolution imaging of point targets embedded in a reciprocal background medium [A. J. Devaney, "Super-resolution imaging using time-reversal and MUSIC," J. Acoust. Soc. Am. (to be published)] is generalized to the case where the transmitter and receiver sensor arrays need not be coincident and for cases where the background medium can be nonreciprocal. The new theory developed herein is based on the singular value decomposition of the generalized multistatic data matrix of the sensor system rather than the standard eigenvector/eigenvalue decomposition of the time-reversal matrix as was employed in the above-mentioned work and other treatments of time-reversal imaging [Prada, Thomas, and Fink, "The iterative time reversal process: Analysis of the convergence," J. Acoust. Soc. Am. 97, 62 (1995); Prada et al., "Decomposition of the time reversal operator: Detection and selective focusing on two scatterers," J. Acoust. Soc. Am. 99, 2067 (1996)]. A generalized multiple signal classification (MUSIC) algorithm is derived that allows super-resolution imaging of both well-resolved and non-well-resolved point targets from arbitrary sensor array geometries. MUSIC exploits the orthogonal nature of the scatterer and noise subspaces defined by the singular vectors of the multistatic data matrix to form scatterer images. The time-reversal/MUSIC algorithm is tested and validated in two computer simulations of offset vertical seismic profiling where the sensor sources are aligned along the earth's surface and the receiver array is aligned along a subsurface borehole. All results demonstrate the high contrast, high resolution imaging capabilities of this new algorithm combination when compared with "classical" backpropagation or field focusing. Above and beyond the application of seismo-acoustic imaging, the time-reversal super-resolution theory has applications in ocean acoustics for target location, and ultrasonic nondestructive evaluation of

  16. High time resolution ion temperature profile measurements on PBX

    SciTech Connect

    Gammel, G.; Kaita, R.; Fonck, R.; Jaehnig, K.; Powell, E.

    1986-05-01

    Ion temperature profiles with a time resolution of 2 to 5 ms have been measured on PBX by charge-exchange-recombination spectroscopy (CXRS) and a neutral-particle charge-exchange analyzer (NPA). The sightlines of both diagnostics crossed the trajectory of a near-perpendicular heating beam, which enhanced the local neutral density (proportional to signal strength) and provided spatial resolution. The time resolution of these two independent techniques is sufficient to see sawtooth oscillations and other MHD activity. Effects of these phenomena on the toroidal rotation velocity profile, v/sub phi/(r), are clearly observed by CXRS. For example, a sharp drop in the central v/sub phi/ occurs at the sawtooth crash, followed by a linear rise during the quiescent phase. The NPA results are compared with those from CXRS.

  17. Time resolution studies using digital constant fraction discrimination

    NASA Astrophysics Data System (ADS)

    Fallu-Labruyere, A.; Tan, H.; Hennig, W.; Warburton, W. K.

    2007-08-01

    Digital Pulse Processing (DPP) modules are being increasingly considered to replace modular analog electronics in medium-scale nuclear physics experiments (100-1000s of channels). One major area remains, however, where it has not been convincingly demonstrated that DPP modules are competitive with their analog predecessors—time-of-arrival measurement. While analog discriminators and time-to-amplitude converters can readily achieve coincidence time resolutions in the 300-500 ps range with suitably fast scintillators and Photomultiplier Tubes (PMTs), this capability has not been widely demonstrated with DPPs. Some concern has been expressed, in fact, that such time resolutions are attainable with the 10 ns sampling times that are presently commonly available. In this work, we present time-coincidence measurements taken using a commercially available DPP (the Pixie-4 from XIA LLC) directly coupled to pairs of fast PMTs mated with either LSO or LaBr 3 scintillator crystals and excited by 22Na γ-ray emissions. Our results, 886 ps for LSO and 576 ps for LaBr 3, while not matching the best literature results using analog electronics, are already well below 1 ns and fully adequate for a wide variety of experiments. These results are shown not to be limited by the DPPs themselves, which achieved 57 ps time resolution using a pulser, but are degraded in part both by the somewhat limited number of photoelectrons we collected and by a sub-optimum choice of PMT. Analysis further suggests that increasing the sampling speed would further improve performance. We therefore conclude that DPP time-of-arrival resolution is already adequate to supplant analog processing in many applications and that further improvements could be achieved with only modest efforts.

  18. Processing time using Datatrieve-11, clunks, and FORTRAN

    SciTech Connect

    Horning, R.R.; Goode, W.E.

    1983-01-01

    Although Datatrieve-11 processes dates with 100-ns resolution using clunks, it has no provision for processing time. This paper describes a set of Datatrieve-11 procedures and FORTRAN-callable subroutines for handling time, as well as dates, expressed in clunks. Although the FORTRAN-callable subroutines use RMS modules, these modules can be extracted from the appropriate RMS library, allowing FORTRAN programs to be linked to an FCS library instead of to RMS.

  19. Method for improving the time resolution of a TOF system

    NASA Astrophysics Data System (ADS)

    Li, Shao-Li; Heng, Yue-Kun; Zhao, Tian-Chi; Fu, Zai-Wei; Liu, Shu-Lin; Qian, Sen; Liu, Shu-Dong; Chen, Xiao-Hui; Jia, Ru; Huang, Guo-Rui; Lei, Xiang-Cui

    2013-01-01

    In order to study the possibility of improving the timing performance of the time of flight (TOF) systems, which are made of plastic scintillator counters, and read out by photomultiplier tubes (PMT) with mesh dynodes and conventional electronics, we have conducted a study using faster PMTs and ultra fast waveform digitizers to read out the plastic scintillators. Different waveform analysis methods are used to calculate the time resolution of such a system. Results are compared with the conventional discriminating method based on a threshold and pulse height. Our tests and analysis show that significant timing performance improvements can be achieved by using this new system.

  20. STIC3 - Silicon Photomultiplier Timing Chip with picosecond resolution

    NASA Astrophysics Data System (ADS)

    Stankova, Vera; Shen, Wei; Briggl, Konrad; Chen, Huangshan; Fischer, Peter; Gil, Alejandro; Harion, Tobias; Kiworra, Volker; Munwes, Yonathan; Ritzert, Michael; Schultz-Coulon, Hans-Christian

    2015-07-01

    The diagnostic of pancreas and prostate cancer is a challenging task due to the background noise coming from the closer organs. The EndoToFPET-US project aims to combine the synergy between metabolic and anatomical (ultrasound) image in order to improve the precision in the tumor localization. The goal of the project is to develop a Positron Emission Tomography (PET) system that provides a time-of-flight resolution of 200 ps FWHM for improving the signal to noise ratio and further to improve the medical image quality. In order to achieve this purpose an ASIC has been designed for very high timing resolution in time-of-flight (ToF) applications. In this paper we present the ASIC performance and the first characterization measurements with the 64-channels prototype version (STiC3). Measurements are performed with LYSO scintillator crystal and a Multi Pixel Photon Counter (MPPC). Measurements with the chip show an analog-front-end stage jitter of 35 ps for the first photo-electron equivalent charge and reach 18 ps for the third photo-electron. Coincidence time resolution (CTR) of 240 ps FWHM is measured with 3.1×3.1×15 mm3 LYSO crystal and 50 μm pixel pitch MPPC. Further optimization including the Time-to-Digital Converter (TDC) non-linearity corrections and setup fine tuning are ongoing for achieving the desired CTR of 200 ps FWHM.

  1. Real-time computation of subdiffraction-resolution fluorescence images.

    PubMed

    Wolter, S; Schüttpelz, M; Tscherepanow, M; VAN DE Linde, S; Heilemann, M; Sauer, M

    2010-01-01

    In the recent past, single-molecule based localization or photoswitching microscopy methods such as stochastic optical reconstruction microscopy (STORM) or photoactivated localization microscopy (PALM) have been successfully implemented for subdiffraction-resolution fluorescence imaging. However, the computational effort needed to localize numerous fluorophores is tremendous, causing long data processing times and thereby limiting the applicability of the technique. Here we present a new computational scheme for data processing consisting of noise reduction, detection of likely fluorophore positions, high-precision fluorophore localization and subsequent visualization of found fluorophore positions in a super-resolution image. We present and benchmark different algorithms for noise reduction and demonstrate the use of non-maximum suppression to quickly find likely fluorophore positions in high depth and very noisy images. The algorithm is evaluated and compared in terms of speed, accuracy and robustness by means of simulated data. On real biological samples, we find that real-time data processing is possible and that super-resolution imaging with organic fluorophores of cellular structures with approximately 20 nm optical resolution can be completed in less than 10 s. PMID:20055915

  2. Variable Resistance of RMS to Interferon γ Signaling.

    PubMed

    Simon-Keller, Katja; Mößinger, Katharina; Bohlender, Anna-Lena; Ströbel, Philipp; Marx, Alexander

    2012-01-01

    Aims. Chimeric T cells directed to the γ-subunit of the fetal acetylcholine receptor (fAChR) produce large amounts of interferon-γ (IFNγ) on coculture with fAChR-expressing rhabdomyosarcoma (RMS) cells prior to RMS cell death. The aim of this study was to elucidate whether IFNγ blocks proliferation and survival of RMS cells and modulates expression of genes with relevance for cytotoxicity of chimeric T cells. Methods. Expression levels of IFNγ receptor (IFNGR), AChR, MHCI, MHCII, and CIITA (class II transactivator) by RMS were checked by flow cytometry, qRT-PCR, and western blot. Proliferation and cell survival were investigated by annexin V and propidium iodide staining and MTT (thiazolyl-blue-tetrazolium-bromide) assay. Key phosphorylation and binding sites of IFNGRs were checked by DNA sequencing. Results. IFNγ treatment blocked proliferation in 3 of 6 RMS cell lines, but reduced survival in only one. IFNGR was expressed at levels comparable to controls and binding sites for JAK and STAT1 were intact. Induction of several target genes (e.g., AChR, MHCI, and MHCII) by IFNγ was detected on the RNA level but not protein level. Conclusions. IFNγ does not significantly contribute to the killing of RMS cells by fAChR directed chimeric T cells. Signalling downstream of the IFNR receptor, including the posttranscriptional level, is impaired in most RMS cell lines. PMID:22919516

  3. Variable Resistance of RMS to Interferon γ Signaling

    PubMed Central

    Simon-Keller, Katja; Mößinger, Katharina; Bohlender, Anna-Lena; Ströbel, Philipp; Marx, Alexander

    2012-01-01

    Aims. Chimeric T cells directed to the γ-subunit of the fetal acetylcholine receptor (fAChR) produce large amounts of interferon-γ (IFNγ) on coculture with fAChR-expressing rhabdomyosarcoma (RMS) cells prior to RMS cell death. The aim of this study was to elucidate whether IFNγ blocks proliferation and survival of RMS cells and modulates expression of genes with relevance for cytotoxicity of chimeric T cells. Methods. Expression levels of IFNγ receptor (IFNGR), AChR, MHCI, MHCII, and CIITA (class II transactivator) by RMS were checked by flow cytometry, qRT-PCR, and western blot. Proliferation and cell survival were investigated by annexin V and propidium iodide staining and MTT (thiazolyl-blue-tetrazolium-bromide) assay. Key phosphorylation and binding sites of IFNGRs were checked by DNA sequencing. Results. IFNγ treatment blocked proliferation in 3 of 6 RMS cell lines, but reduced survival in only one. IFNGR was expressed at levels comparable to controls and binding sites for JAK and STAT1 were intact. Induction of several target genes (e.g., AChR, MHCI, and MHCII) by IFNγ was detected on the RNA level but not protein level. Conclusions. IFNγ does not significantly contribute to the killing of RMS cells by fAChR directed chimeric T cells. Signalling downstream of the IFNR receptor, including the posttranscriptional level, is impaired in most RMS cell lines. PMID:22919516

  4. The time resolution domain of stellar radio astronomy

    NASA Technical Reports Server (NTRS)

    Bookbinder, J.

    1985-01-01

    The high time resolution (HTR) radio observation of late-type stars and RS CVn systems is discussed. Some examples of these sources are addressed, identifying what information HTR observations can provide. HTR can provide important information on flares in late-type stars, and can be used to study coronal structure and the particle acceleration mechanism in these stars. The possible use of HTR to establish the nature of quiescent emission form RS CVn systems is discussed.

  5. Escaping ion measurement with high time resolution on CHS

    SciTech Connect

    Shinohara, K.; Isobe, M.; Darrow, D. S.

    2006-10-15

    A scintillator-based lost ion probe can measure the temporal evolution of both the gyroradius and the pitch angle of energetic ions escaping a magnetically confined plasma. For the probe on the Compact Helical System, the time resolution of this detailed two-dimensional measurement is determined by a framing rate of the video camera that records the luminous images produced by the ions striking the scintillator plate. The framing rate of the old camera was 30 Hz, thus the time resolution was about 33 ms. Our interest is to understand the energetic ion transport in fast events such as a bursting energetic ion driven mode. The typical time scale of these events is less than 1 ms, meaning that the old camera was too slow. By replacing it with an image-intensified high-speed video camera system, the temporal resolution was improved from 33 to 0.07 ms. We have successfully installed the fast camera and captured some fast events caused by magnetohydrodynamics, which were unobservable using the original camera.

  6. High frequency resolution terahertz time-domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Sangala, Bagvanth Reddy

    2013-12-01

    A new method for the high frequency resolution terahertz time-domain spectroscopy is developed based on the characteristic matrix method. This method is useful for studying planar samples or stack of planar samples. The terahertz radiation was generated by optical rectification in a ZnTe crystal and detected by another ZnTe crystal via electro-optic sampling method. In this new characteristic matrix based method, the spectra of the sample and reference waveforms will be modeled by using characteristic matrices. We applied this new method to measure the optical constants of air. The terahertz transmission through the layered systems air-Teflon-air-Quartz-air and Nitrogen gas-Teflon-Nitrogen gas-Quartz-Nitrogen gas was modeled by the characteristic matrix method. A transmission coefficient is derived from these models which was optimized to fit the experimental transmission coefficient to extract the optical constants of air. The optimization of an error function involving the experimental complex transmission coefficient and the theoretical transmission coefficient was performed using patternsearch algorithm of MATLAB. Since this method takes account of the echo waveforms due to reflections in the layered samples, this method allows analysis of longer time-domain waveforms giving rise to very high frequency resolution in the frequency-domain. We have presented the high frequency resolution terahertz time-domain spectroscopy of air and compared the results with the literature values. We have also fitted the complex susceptibility of air to the Lorentzian and Gaussian functions to extract the linewidths.

  7. Sensitivity of The High-resolution Wam Model With Respect To Time Step

    NASA Astrophysics Data System (ADS)

    Kasemets, K.; Soomere, T.

    The northern part of the Baltic Proper and its subbasins (Bothnian Sea, the Gulf of Finland, Moonsund) serve as a challenge for wave modellers. In difference from the southern and the eastern parts of the Baltic Sea, their coasts are highly irregular and contain many peculiarities with the characteristic horizontal scale of the order of a few kilometres. For example, the northern coast of the Gulf of Finland is extremely ragged and contains a huge number of small islands. Its southern coast is more or less regular but has up to 50m high cliff that is frequently covered by high forests. The area also contains numerous banks that have water depth a couple of meters and that may essentially modify wave properties near the banks owing to topographical effects. This feature suggests that a high-resolution wave model should be applied for the region in question, with a horizontal resolution of an order of 1 km or even less. According to the Courant-Friedrich-Lewy criterion, the integration time step for such models must be of the order of a few tens of seconds. A high-resolution WAM model turns out to be fairly sensitive with respect to the particular choice of the time step. In our experiments, a medium-resolution model for the whole Baltic Sea was used, with the horizontal resolution 3 miles (3' along latitudes and 6' along longitudes) and the angular resolution 12 directions. The model was run with steady wind blowing 20 m/s from different directions and with two time steps (1 and 3 minutes). For most of the wind directions, the rms. difference of significant wave heights calculated with differ- ent time steps did not exceed 10 cm and typically was of the order of a few per cents. The difference arose within a few tens of minutes and generally did not increase in further computations. However, in the case of the north wind, the difference increased nearly monotonously and reached 25-35 cm (10-15%) within three hours of integra- tion whereas mean of significant wave

  8. Challenger's RMS arm grasps SPAS-01 during proximity operations

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Challenger's remote manipulator system (RMS) arm grasps Shuttle pallet satellite (SPAS-01) during proximity operations. The frame shows a number of reflections on the window, located overhead in the aft flight deck.

  9. A high resolution Timing Counter for the MEG II experiment

    NASA Astrophysics Data System (ADS)

    De Gerone, M.; Bevilacqua, A.; Biasotti, M.; Boca, G.; Cattaneo, P. W.; Gatti, F.; Nishimura, M.; Ootani, W.; Pizzigoni, G.; Rossella, M.; Shibata, N.; Siccardi, F.; Simonetta, M.; Uchiyama, Y.; Yoshida, K.

    2016-07-01

    The development of a Timing Counter detector designed for the MEGII upgrade of the MEG experiment, which strives to improve the sensitivity on the μ+ →e+ γ decay of an order of magnitude, is presented. It is based on two sets of counters (sectors) arranged on a semi-cylindrical structure; each sector consists of 256 counters. Each counter consists of tile of fast scintillator with a dual-side read-out based on SiPM arrays in series connection. The high granularity has two advantages: optimized size for achieving high resolution (75 ps) for the single counter, and a signal e+ crosses several counters, so that resolution improves by averaging multiple time measurements. A prototype has been built and tested both in BTF and PSI facilities in order to prove the multi-hit scheme in MEG-like beam conditions. A 35 ps resolution with eight hits has been obtained with a e+ beam at 100 kHz. The first sector will be tested in the MEG II pre-engineering run planned at the end of 2015.

  10. RMS ENVELOPE BACK-PROPAGATION IN THE XAL ONLINE MODEL

    SciTech Connect

    Allen, Christopher K; Sako, Hiroyuki; Ikegami, Masanori

    2009-01-01

    The ability to back-propagate RMS envelopes was added to the J-PARC XAL online model. Specifically, given an arbitrary downstream location, the online model can propagate the RMS envelopes backward to an arbitrary upstream location. This feature provides support for algorithms estimating upstream conditions from downstream data. The upgrade required significant refactoring, which we outline. We also show simulations using the new feature.

  11. Temporal resolution limits of time-to-frequency transformations.

    PubMed

    Fernández-Pousa, Carlos R

    2006-10-15

    Time-to-frequency converters are devices that transfer the intensity of a light pulse to its spectrum. The two architectures of these converters are studied: a dispersive line followed by a phase modulator and a single time lens operating in the spectral Fraunhofer regime. These two configurations are shown not to be equivalent in general: the first one provides an incoherent time-to-frequency mapping, whereas the second depends on the degree of coherence of the pulse. In this case, the recorded spectrum is the intensity of a partially coherent residually dispersed pulse, and the spectral Fraunhofer condition is the requirement of negligible residual dispersion. Converters operated outside the spectral Fraunhofer limit can achieve a subpicosecond resolution with moderate time-lens phase factors. Their use for pulse characterization is briefly analyzed. PMID:17001396

  12. Study on GASTOF - A 10 ps resolution timing detector

    NASA Astrophysics Data System (ADS)

    Bonnet, Luc; Liao, Junhui; Piotrzkowski, Krzysztof

    2014-10-01

    GASTOF (Gas Time Of Flight) is a type of fast-time detector affiliated to the HPS (High Precision Spectrometer) project which is a forward physics collaborator within CMS. It is a picosecond time resolution Cherenkov gas detector using very fast single anode micro-channel plate photomultiplier (Hamamatsu R3809U-50 or Photek 210) as a photon detector. We firstly measured characteristics of these two types of MCP-PMTs by a fast laser pulse in lab. Then two GASTOF detectors both equipped with a Hamamatsu R3809U-50 tube were studied in a beam test at CERN. According to the analysis of beam test data, the average number of photoelectrons (phe) was 2.0 for both phototubes. By making a cut on the number of photoelectrons such that the mean phe was 3.6 in one phototube and 3.2 in another, we obtained a time resolution of σ ~ 11.7 picosecond (ps) and σ ~ 8.2 ps.

  13. Coherence time measurements using a single detector with variable time resolution.

    PubMed

    Assmann, Marc; Bayer, Manfred

    2012-07-15

    We present a simple technique for measuring coherence times for stationary light fields using a single detector with tunable time resolution. By measuring the equal-time second-order correlation function at varying instrument response functions it is possible to determine the coherence time and also the shape of the temporal decay without the need to record time-resolved data. The technique is demonstrated for pseudothermal light. Possible applications for dynamic light scattering and photon statistics measurements are discussed. PMID:22825142

  14. High-resolution time-frequency distributions for fall detection

    NASA Astrophysics Data System (ADS)

    Amin, Moeness G.; Zhang, Yimin D.; Boashash, Boualem

    2015-05-01

    In this paper, we examine the role of high-resolution time-frequency distributions (TFDs) of radar micro-Doppler signatures for fall detection. The work supports the recent and rising interest in using emerging radar technology for elderly care and assisted living. Spectrograms have been the de facto joint-variable signal representation, depicting the signal power in both time and frequency. Although there have been major advances in designing quadratic TFDs which are superior to spectrograms in terms of detailing the local signal behavior, the contributions of these distributions in the area of human motion classifications and their offerings in enhanced feature extractions have not yet been properly evaluated. The main purpose of this paper is to show the effect of using high-resolution TFD kernels, in lieu of spectrogram, on fall detection. We focus on the extended modified B-distribution (EMBD) and exploit the level of details it provides as compared with the coarse and smoothed time-frequency signatures offered by spectrograms.

  15. Review of the ultrafast time resolution photopolarimeters based on SPADs

    NASA Astrophysics Data System (ADS)

    Słowikowska, Aga; Kanbach, Gottfried; Goździewski, Krzysztof; Krzeszowski, Krzysztof; Rau, Arne

    2014-02-01

    We review photopolarimeters that are based on the Single Photon Avalanche Diodes (SPADs) and were designed, built, developed, and extensively used for high time resolution studies of astrophysical sources. Examples of such detectors are OPTIMA, GASP, AquEYE, and IquEYE which can measure the time of arrival of single optical photons with an accuracy of down to 50 picoseconds. We describe the most exciting results obtained with the SPADs detectors starting from the best existing optical polarimetric measurements of the Crab pulsar, the discovery of the first optical magnetar and its quasi-periodic oscillations, as well as a verification of exoplanets around eclipsing cataclysmic variables. Additionally, we discuss possible applications of such detectors for asteroseismology.

  16. ASIC-enabled High Resolution Optical Time Domain Reflectometer

    NASA Astrophysics Data System (ADS)

    Skendzic, Sandra

    Fiber optics has become the preferred technology in communication systems because of what it has to offer: high data transmission rates, immunity to electromagnetic interference, and lightweight, flexible cables. An optical time domain reflectometer (OTDR) provides a convenient method of locating and diagnosing faults (e.g. break in a fiber) along a fiber that can obstruct crucial optical pathways. Both the ability to resolve the precise location of the fault and distinguish between two discrete, closely spaced faults are figures of merit. This thesis presents an implementation of a high resolution OTDR through the use of a compact and programmable ASIC (application specific integrated circuit). The integration of many essential OTDR functions on a single chip is advantageous over existing commercial instruments because it enables small, lightweight packaging, and offers low power and cost efficiency. Furthermore, its compactness presents the option of placing multiple ASICs in parallel, which can conceivably ease the characterization of densely populated fiber optic networks. The OTDR ASIC consists of a tunable clock, pattern generator, precise timer, electrical receiver, and signal sampling circuit. During OTDR operation, the chip generates narrow electrical pulse, which can then be converted to optical format when coupled with an external laser diode driver. The ASIC also works with an external photodetector to measure the timing and amplitude of optical reflections in a fiber. It has a 1 cm sampling resolution, which allows for a 2 cm spatial resolution. While this OTDR ASIC has been previously demonstrated for multimode fiber fault diagnostics, this thesis focuses on extending its functionality to single mode fiber. To validate this novel approach to OTDR, this thesis is divided into five chapters: (1) introduction, (2) implementation, (3), performance of ASIC-based OTDR, (4) exploration in optical pre-amplification with a semiconductor optical amplifier, and

  17. 10 ps resolution, 160 ns full scale range and less than 1.5% differential non-linearity time-to-digital converter module for high performance timing measurements

    SciTech Connect

    Markovic, B.; Tamborini, D.; Villa, F.; Tisa, S.; Tosi, A.; Zappa, F.

    2012-07-15

    We present a compact high performance time-to-digital converter (TDC) module that provides 10 ps timing resolution, 160 ns dynamic range and a differential non-linearity better than 1.5% LSB{sub rms}. The TDC can be operated either as a general-purpose time-interval measurement device, when receiving external START and STOP pulses, or in photon-timing mode, when employing the on-chip SPAD (single photon avalanche diode) detector for detecting photons and time-tagging them. The instrument precision is 15 ps{sub rms} (i.e., 36 ps{sub FWHM}) and in photon timing mode it is still better than 70 ps{sub FWHM}. The USB link to the remote PC allows the easy setting of measurement parameters, the fast download of acquired data, and their visualization and storing via an user-friendly software interface. The module proves to be the best candidate for a wide variety of applications such as: fluorescence lifetime imaging, time-of-flight ranging measurements, time-resolved positron emission tomography, single-molecule spectroscopy, fluorescence correlation spectroscopy, diffuse optical tomography, optical time-domain reflectometry, quantum optics, etc.

  18. 10 ps resolution, 160 ns full scale range and less than 1.5% differential non-linearity time-to-digital converter module for high performance timing measurements.

    PubMed

    Markovic, B; Tamborini, D; Villa, F; Tisa, S; Tosi, A; Zappa, F

    2012-07-01

    We present a compact high performance time-to-digital converter (TDC) module that provides 10 ps timing resolution, 160 ns dynamic range and a differential non-linearity better than 1.5% LSB(rms). The TDC can be operated either as a general-purpose time-interval measurement device, when receiving external START and STOP pulses, or in photon-timing mode, when employing the on-chip SPAD (single photon avalanche diode) detector for detecting photons and time-tagging them. The instrument precision is 15 ps(rms) (i.e., 36 ps(FWHM)) and in photon timing mode it is still better than 70 ps(FWHM). The USB link to the remote PC allows the easy setting of measurement parameters, the fast download of acquired data, and their visualization and storing via an user-friendly software interface. The module proves to be the best candidate for a wide variety of applications such as: fluorescence lifetime imaging, time-of-flight ranging measurements, time-resolved positron emission tomography, single-molecule spectroscopy, fluorescence correlation spectroscopy, diffuse optical tomography, optical time-domain reflectometry, quantum optics, etc. PMID:22852708

  19. Field energy and RMS emittance in intense particle beams

    SciTech Connect

    Wangler, T.P.; Crandall, K.R.; Mills, R.S.; Reiser, M.

    1986-04-25

    An equation is presented for continuous beam with azimuthal symmetry and continuous linear focusing; the equation expresses a relationship between the rate of change for squared rms emittance and the rate of change for a quantity we call the nonlinear field energy. The nonlinear field energy depends on the shape of the charge distribution and corresponds to the residual field energy possessed by beams with nonuniform charge distributions. The equation can be integrated for the case of an rms matched beam to yield a formula for space-charge-induced emittance growth that we have tested numerically for a variety of initial distributions. The results provide a framework for discussing the scaling of rms emittance growth and an explanation for the well-established lower limit on output emittance.

  20. Precision cosmology with time delay lenses: high resolution imaging requirements

    NASA Astrophysics Data System (ADS)

    Meng, Xiao-Lei; Treu, Tommaso; Agnello, Adriano; Auger, Matthew W.; Liao, Kai; Marshall, Philip J.

    2015-09-01

    Lens time delays are a powerful probe of cosmology, provided that the gravitational potential of the main deflector can be modeled with sufficient precision. Recent work has shown that this can be achieved by detailed modeling of the host galaxies of lensed quasars, which appear as ``Einstein Rings'' in high resolution images. The distortion of these arcs and counter-arcs, as measured over a large number of pixels, provides tight constraints on the difference between the gravitational potential between the quasar image positions, and thus on cosmology in combination with the measured time delay. We carry out a systematic exploration of the high resolution imaging required to exploit the thousands of lensed quasars that will be discovered by current and upcoming surveys with the next decade. Specifically, we simulate realistic lens systems as imaged by the Hubble Space Telescope (HST), James Webb Space Telescope (JWST), and ground based adaptive optics images taken with Keck or the Thirty Meter Telescope (TMT). We compare the performance of these pointed observations with that of images taken by the Euclid (VIS), Wide-Field Infrared Survey Telescope (WFIRST) and Large Synoptic Survey Telescope (LSST) surveys. We use as our metric the precision with which the slope γ' of the total mass density profile ρtotpropto r-γ' for the main deflector can be measured. Ideally, we require that the statistical error on γ' be less than 0.02, such that it is subdominant to other sources of random and systematic uncertainties. We find that survey data will likely have sufficient depth and resolution to meet the target only for the brighter gravitational lens systems, comparable to those discovered by the SDSS survey. For fainter systems, that will be discovered by current and future surveys, targeted follow-up will be required. However, the exposure time required with upcoming facilitites such as JWST, the Keck Next Generation Adaptive Optics System, and TMT, will only be of

  1. Precision cosmology with time delay lenses: High resolution imaging requirements

    SciTech Connect

    Meng, Xiao -Lei; Treu, Tommaso; Agnello, Adriano; Auger, Matthew W.; Liao, Kai; Marshall, Philip J.

    2015-09-28

    Lens time delays are a powerful probe of cosmology, provided that the gravitational potential of the main deflector can be modeled with sufficient precision. Recent work has shown that this can be achieved by detailed modeling of the host galaxies of lensed quasars, which appear as ``Einstein Rings'' in high resolution images. The distortion of these arcs and counter-arcs, as measured over a large number of pixels, provides tight constraints on the difference between the gravitational potential between the quasar image positions, and thus on cosmology in combination with the measured time delay. We carry out a systematic exploration of the high resolution imaging required to exploit the thousands of lensed quasars that will be discovered by current and upcoming surveys with the next decade. Specifically, we simulate realistic lens systems as imaged by the Hubble Space Telescope (HST), James Webb Space Telescope (JWST), and ground based adaptive optics images taken with Keck or the Thirty Meter Telescope (TMT). We compare the performance of these pointed observations with that of images taken by the Euclid (VIS), Wide-Field Infrared Survey Telescope (WFIRST) and Large Synoptic Survey Telescope (LSST) surveys. We use as our metric the precision with which the slope γ' of the total mass density profile ρtot∝ r–γ' for the main deflector can be measured. Ideally, we require that the statistical error on γ' be less than 0.02, such that it is subdominant to other sources of random and systematic uncertainties. We find that survey data will likely have sufficient depth and resolution to meet the target only for the brighter gravitational lens systems, comparable to those discovered by the SDSS survey. For fainter systems, that will be discovered by current and future surveys, targeted follow-up will be required. Furthermore, the exposure time required with upcoming facilitites such as JWST, the Keck Next Generation Adaptive Optics System, and TMT, will

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

    NASA Astrophysics Data System (ADS)

    Unruh, Tobias; Neuhaus, Jürgen; Petry, Winfried

    2007-10-01

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

  3. Sub-picosecond Resolution Time-to-Digital Converter

    SciTech Connect

    Ph D, Vladimir Bratov; Ph D, Vladimir Katzman; MS EE, Jeb Binkley

    2006-03-30

    Time-to-digital converters with sub-picosecond resolutions are needed to satisfy the requirements of time-on-flight measurements of the next generation of high energy and nuclear physics experiments. The converters must be highly integrated, power effective, low cost, and feature plug-and-play capabilities to handle the increasing number of channels (up to hundreds of millions) in future Department of Energy experiments. Current state-off-the-art time-to-digital converter integrated circuits do not have the sufficient degree of integration and flexibility to fulfill all the described requirements. During Phase I, the Advanced Science and Novel Technology Company in cooperation with the nuclear physics division of the Oak Ridge National Laboratory has developed the architecture of a novel time-to-digital converter with multiple channels connected to an external processor through a special interfacing block and synchronized by clock signals generated by an internal phase-locked loop. The critical blocks of the system including signal delay lines and delay-locked loops with proprietary differential delay cells, as well as the required digital code converter and the clock period counter have been designed and simulated using the advanced SiGe120 BiCMOS technological process. The results of investigations demonstrate a possibility to achieve the digitization accuracy within 1ps. ADSANTEC has demonstrated the feasibility of the proposed concept in computer simulations. The proposed system will be a critical component for the next generation of NEP experiments.

  4. Synthesis of rainfall time series in a high temporal resolution

    NASA Astrophysics Data System (ADS)

    Callau Poduje, Ana Claudia; Haberlandt, Uwe

    2014-05-01

    In order to optimize the design and operation of urban drainage systems, long and continuous rain series in a high temporal resolution are essential. As the length of the rainfall records is often short, particularly the data available with the temporal and regional resolutions required for urban hydrology, it is necessary to find some numerical representation of the precipitation phenomenon to generate long synthetic rainfall series. An Alternating Renewal Model (ARM) is applied for this purpose, which consists of two structures: external and internal. The former is the sequence of wet and dry spells, described by their durations which are simulated stochastically. The internal structure is characterized by the amount of rain corresponding to each wet spell and its distribution within the spell. A multivariate frequency analysis is applied to analyze the internal structure of the wet spells and to generate synthetic events. The stochastic time series must reproduce the statistical characteristics of observed high resolution precipitation measurements used to generate them. The spatio-temporal interdependencies between stations are addressed by resampling the continuous synthetic series based on the Simulated Annealing (SA) procedure. The state of Lower-Saxony and surrounding areas, located in the north-west of Germany is used to develop the ARM. A total of 26 rainfall stations with high temporal resolution records, i.e. rainfall data every 5 minutes, are used to define the events, find the most suitable probability distributions, calibrate the corresponding parameters, simulate long synthetic series and evaluate the results. The length of the available data ranges from 10 to 20 years. The rainfall series involved in the different steps of calculation are compared using a rainfall-runoff model to simulate the runoff behavior in urban areas. The EPA Storm Water Management Model (SWMM) is applied for this evaluation. The results show a good representation of the

  5. High resolution geodetic techniques for monitoring fluid levels over time

    NASA Astrophysics Data System (ADS)

    Hare, Jennifer Thompson

    1998-11-01

    In the first study, a novel surveillance technique is developed in which surface gravity observations are used to monitor the progress of a gas cap waterflood in the 8200 ft (2500 m) deep Prudhoe Bay reservoir, Alaska. This cost-effective method requires that high-precision gravity surveys be repeated every 3 to 5 years. Differences in the gravity field with time reflect changes in the reservoir fluid density distribution. A preliminary field test at Prudhoe Bay indicates survey accuracy of 5 to 10 mu Gal can be achieved for gravity data using a modified Lacoste & Romberg "G" type meter or Scintrex CG-3M combined with Global Positioning System (GPS) positioning. Forward gravity modeling of a suite of reservoir simulations of the proposed waterflood predicts variation in surface measurements of 100 mu Gal after 5 years of injection, and 180 to 250 mu Gal after 15 years. A constrained, least-squares method is used to invert synthetic gravity data for subsurface density distributions. The modeling procedure has been formulated to allow testing of the models for sensitivity to gravity sampling patterns, noise characteristics, and various constraints on model parameters such as density range, total mass, and model moment of inertia. Horizontal feature resolution of the waterflood is about 5000 ft (1520 m) for constrained inverse models from synthetic gravity with 5 mu Gal standard deviation noise. Results of the modeling indicate that inversion of time-lapse gravity data is a viable and promising technique for monitoring reservoir gas cap waterfloods. In the second study, the problem of how to estimate ancient lake levels from the geomorphology of remnant shoreline terraces is investigated. High resolution, GPS controlled, topographic data from around the highstand shoreline of Pleistocene Lake Lahontan in western Nevada provide the means for isolating coherent terrace features which are related to the paleoshoreline level. Determination of an unambiguous point or

  6. Fast time-resolved electrostatic force microscopy: Achieving sub-cycle time resolution.

    PubMed

    Karatay, Durmus U; Harrison, Jeffrey S; Glaz, Micah S; Giridharagopal, Rajiv; Ginger, David S

    2016-05-01

    The ability to measure microsecond- and nanosecond-scale local dynamics below the diffraction limit with widely available atomic force microscopy hardware would enable new scientific studies in fields ranging from biology to semiconductor physics. However, commercially available scanning-probe instruments typically offer the ability to measure dynamics only on time scales of milliseconds to seconds. Here, we describe in detail the implementation of fast time-resolved electrostatic force microscopy using an oscillating cantilever as a means to measure fast local dynamics following a perturbation to a sample. We show how the phase of the oscillating cantilever relative to the perturbation event is critical to achieving reliable sub-cycle time resolution. We explore how noise affects the achievable time resolution and present empirical guidelines for reducing noise and optimizing experimental parameters. Specifically, we show that reducing the noise on the cantilever by using photothermal excitation instead of piezoacoustic excitation further improves time resolution. We demonstrate the discrimination of signal rise times with time constants as fast as 10 ns, and simultaneous data acquisition and analysis for dramatically improved image acquisition times. PMID:27250430

  7. Fast time-resolved electrostatic force microscopy: Achieving sub-cycle time resolution

    NASA Astrophysics Data System (ADS)

    Karatay, Durmus U.; Harrison, Jeffrey S.; Glaz, Micah S.; Giridharagopal, Rajiv; Ginger, David S.

    2016-05-01

    The ability to measure microsecond- and nanosecond-scale local dynamics below the diffraction limit with widely available atomic force microscopy hardware would enable new scientific studies in fields ranging from biology to semiconductor physics. However, commercially available scanning-probe instruments typically offer the ability to measure dynamics only on time scales of milliseconds to seconds. Here, we describe in detail the implementation of fast time-resolved electrostatic force microscopy using an oscillating cantilever as a means to measure fast local dynamics following a perturbation to a sample. We show how the phase of the oscillating cantilever relative to the perturbation event is critical to achieving reliable sub-cycle time resolution. We explore how noise affects the achievable time resolution and present empirical guidelines for reducing noise and optimizing experimental parameters. Specifically, we show that reducing the noise on the cantilever by using photothermal excitation instead of piezoacoustic excitation further improves time resolution. We demonstrate the discrimination of signal rise times with time constants as fast as 10 ns, and simultaneous data acquisition and analysis for dramatically improved image acquisition times.

  8. A resource conflict resolution problem formulated in continuous time

    NASA Astrophysics Data System (ADS)

    Gaver, D. P.; Fayolle, G.; Weiss, A.

    1985-08-01

    In many situations involving data transmission from diverse sources there can be conflict for a limited number of channels or other facilities. Uncoordinated attempts by several sources to use a single facility can result in collision, the destruction of all participants in the collision, meaning the loss of the transmission, and hence the need for re-transmission. An important problem concerns the development of workable procedures for alleviating the conflict and corresponding message delay problems. Often such problems are viewed as occurring in discrete time: slots of equal length occur in temporal succession, and each slot can handle just one packet of data at a time, if two or more packets try to use the same slot simultaneously, a collision occurs that somehow must be resolved. A recent paper analyzed a stack protocol for handling such a situation, but there are many other proposals. This report is concerned with some simple models for a single facility (channel), and for contention or conflict resolution. The models are formulated in a continuous-time manner: messages, or numbers of packets constituting messages, are long, meaning that they occupy many consecutive slots on the average if a single transmission is occurring.

  9. Challenger's RMS arm grasps SPAS-01 during proximity operations

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Challenger's remote manipulator system (RMS) arm grasps Shuttle pallet satellite (SPAS-01) during proximity operations. Behind the SPAS-01 can be seen the clouded surface of the earth. The frame shows a number of reflections on the window, located overhead in the aft flight deck.

  10. RMS end effector waiting for command and SPAS-01 nearby

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The end effector of the remote manipulator system (RMS) appears to be waiting for its next command at the top of this frame and the Shuttle pallet satellite (SPAS-01), in its free flying mode, appears nearby. The three letters legible on the SPAS stand for Messerschmitt-Boelkow-Blohm Gmbit, a West German firm.

  11. Television camera on RMS surveys insulation on Airborne Support Equipment

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The television camera on the end effector of the Canadian-built Remote Manipulator System (RMS) is seen surveying some of the insulation on the Airborne Support Equipment (ASE). Flight controllers called for the survey following the departure of the Advanced Communications Technology Satellite (ACTS) and its Transfer Orbit Stage (TOS).

  12. Determining time resolution of microchannel plate detectors for electron time-of-flight spectrometers.

    PubMed

    Zhang, Qi; Zhao, Kun; Chang, Zenghu

    2010-07-01

    The temporal resolution of a 40 mm diameter chevron microchannel plate (MCP) detector followed by a constant fraction discriminator and a time-to-digital converter was determined by using the third order harmonic of 25 fs Ti:sapphire laser pulses. The resolution was found to deteriorate from 200 to 300 ps as the total voltage applied on the two MCPs increased from 1600 to 2000 V. This was likely due to a partial saturation of the MCP and/or the constant fraction discriminator working with signals beyond its optimum range of pulse width and shape. PMID:20687710

  13. STS-52 CANEX-2 Canadian Target Assembly (CTA) held by RMS over OV-102's PLB

    NASA Technical Reports Server (NTRS)

    1992-01-01

    In operation during STS-52 above the payload bay (PLB) of Columbia, Orbiter Vehicle (OV) 102, is the Canadian Experiment 2 (CANEX-2) Space Vision System (SVS) experiment. Target dots have been placed on the Canadian Target Assembly (CTA), a small spacecraft, in the grasp of the Canadian-built remote manipulator system (RMS) arm. With the shuttle's closed circuit television (CCTV) system, the payload specialist monitors the movement of the 4-foot by 7-foot by 1.5-foot deployed spacecraft, whose surface is covered with many sets of dots of know spacing. As the satellite moved via the RMS, the SVS computer measured the changing position of the dots and provided real-time television display of the location and orientation of the CTA. This type of information is expected to help an operator guide the RMS or the Mobile Servicing System (MSS) of the future when berthing or deploying satellites. Also visible on the RMS is another CANEX-2 payload, the Material Exposure in Low Earth Orbit (MELEO

  14. Multi-time resolution analysis of speech: evidence from psychophysics

    PubMed Central

    Chait, Maria; Greenberg, Steven; Arai, Takayuki; Simon, Jonathan Z.; Poeppel, David

    2015-01-01

    How speech signals are analyzed and represented remains a foundational challenge both for cognitive science and neuroscience. A growing body of research, employing various behavioral and neurobiological experimental techniques, now points to the perceptual relevance of both phoneme-sized (10–40 Hz modulation frequency) and syllable-sized (2–10 Hz modulation frequency) units in speech processing. However, it is not clear how information associated with such different time scales interacts in a manner relevant for speech perception. We report behavioral experiments on speech intelligibility employing a stimulus that allows us to investigate how distinct temporal modulations in speech are treated separately and whether they are combined. We created sentences in which the slow (~4 Hz; Slow) and rapid (~33 Hz; Shigh) modulations—corresponding to ~250 and ~30 ms, the average duration of syllables and certain phonetic properties, respectively—were selectively extracted. Although Slow and Shigh have low intelligibility when presented separately, dichotic presentation of Shigh with Slow results in supra-additive performance, suggesting a synergistic relationship between low- and high-modulation frequencies. A second experiment desynchronized presentation of the Slow and Shigh signals. Desynchronizing signals relative to one another had no impact on intelligibility when delays were less than ~45 ms. Longer delays resulted in a steep intelligibility decline, providing further evidence of integration or binding of information within restricted temporal windows. Our data suggest that human speech perception uses multi-time resolution processing. Signals are concurrently analyzed on at least two separate time scales, the intermediate representations of these analyses are integrated, and the resulting bound percept has significant consequences for speech intelligibility—a view compatible with recent insights from neuroscience implicating multi-timescale auditory

  15. Meteor trail characteristics observed by high time resolution lidar

    NASA Astrophysics Data System (ADS)

    Liu, Y. J.; Plane, J. M. C.; Clemesha, B. R.; Wang, J. H.; Cheng, X. W.

    2014-10-01

    We report and analyse the characteristics of 1382 meteor trails based on a sodium data set of ~ 680 h. The observations were made at Yanqing (115.97° E, 40.47° N), China by a ground-based Na fluorescence lidar. The temporal resolution of the raw profiles is 1.5 s and the altitude resolution is 96 m. We discover some characteristics of meteor trails different from those presented in previous reports. The occurrence heights of the trails follow a double-peak distribution with the peaks at ~ 83.5 km and at ~ 95.5 km, away from the peak height of the regular Na layer. 4.7% of the trails occur below 80 km, and 3.25% above 100 km. 75% of the trails are observed in only one 1.5 s profile, suggesting that the dwell time in the laser beam is not greater than 1.5 s. The peak density of the trails as a function of height is similar to that of the background sodium layer. The raw occurrence height distribution is corrected taking account of three factors which affect the relative lifetime of a trail as a function of height: the meteoroid velocity (which controls the ratio of Na/Na+ ablated); diffusional spreading of the trail; and chemical removal of Na. As a result, the bi-modal distribution is more pronounced. Modelling results show that the higher peak corresponds to a meteoroid population with speeds between 20 and 30 km s-1, whereas the lower peak should arise from much slower particles in a near-prograde orbit. It is inferred that most meteoroids in this data set have masses of ~ 1 mg, in order for ablation to produce sufficient Na atoms to be detected by lidar. Finally, the evolution of longer-duration meteor trails is investigated. Signals at each altitude channel consist of density enhancement bursts with the growth process usually faster than the decay process, and there exists a progressive phase shift among these altitude channels.

  16. STS-82 Mission Specialist Steven Hawley near RMS

    NASA Technical Reports Server (NTRS)

    1997-01-01

    STS-82 Mission Specialist Steven A. Hawley stands beside part of Discovery's Remote Manipulator System (RMS) arm, at right, which he will operate for the capture, berthing and redeployment of the Hubble Space Telescope (HST). The robotic arm also will be used as work platform for the four spacewalkers. Hawley is the prime RMS operator on the flight, which will be the second HST servicing mission. He and the other six members of the crew are making a final inspection of the payload at Launch Pad 39A before launch. STS-82 is scheduled for liftoff on Feb. 11 during a 65- minute launch window which opens at 3:56 a.m. EST.

  17. RMS end effector waiting for command and SPAS-01 nearby

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The end effector of the remote manipulator system (RMS) appears to be waiting for its next command at the top of this frame and the Shuttle pallet satellite (SPAS-01), in its free flying mode, appears nearby. The three letters legible on the SPAS stand for Messerschmitt-Boelkow-Blohm Gmbit, a West German firm. The earth's horizon is visible at the bottom of the frame.

  18. Real-time atomic resolution dynamics of glass surfaces

    NASA Astrophysics Data System (ADS)

    Ashtekar, Sumit Ravindra

    Although glasses are commonplace materials found in every walk of life, they have managed to remain mysterious for centuries. The origins of the defining characteristic of glasses, the glass transition, remain unknown. The glass transition is accompanied by a catastrophic increase in viscosity with a superexponential pace whose underlying reason has been difficult to pin down. Cooperatively rearranging regions (CRR) are playing an increasingly important role in explaining these phenomena. As CRR are only a few nanometers in size, much information can be gained by imaging studies of glasses at the atomic scale. This thesis employs the atomic resolution capabilities of scanning tunneling microscopy (STM) to study glass surfaces in real-time. Initial experiments on metallic glass surfaces discovered localized two-state dynamics of atomic clusters (2-8 atomic diameters) active even below the glass transition temperature (Tg). Atomic scale evidence of spatial and temporal heterogeneity was acquired. After multiple metallic glass surfaces were shown to exhibit these dynamics, it was proposed to be a universal phenomenon on glass surfaces with similar size distribution in terms of their average weighted diameter. The clusters were also shown to be thermally-activated by studying their temperature behavior. Similar dynamics were discovered on amorphous-silicon, which is an important electronic material, amidst the debate whether or not it is a glass. Further, the two-state dynamics were demonstrated to be quenched after the incorporation of hydrogen during the growth process. Individual CRRs are studied while simultaneously ramping their temperature. The single cluster traces showed marked shifts in the local equilibria illustrating a temperature-sensitive energy landscape. It was deduced that spatial heterogeneity (differences in rates at different sites) is the major contributor to the non-exponential glassy relaxations rather than temporal heterogeneity (differences in

  19. The rms-flux relation in accreting white dwarfs: another nova-like variable and the first dwarf nova

    NASA Astrophysics Data System (ADS)

    Van de Sande, M.; Scaringi, S.; Knigge, C.

    2015-04-01

    We report on the detection of the linear rms-flux relation in two accreting white dwarf binary systems: V1504 Cyg and KIC 8751494. The rms-flux relation relates the absolute root-mean-square (rms) variability of the light curve to its mean flux. The light curves analysed were obtained with the Kepler satellite at a 58.8 s cadence. The rms-flux relation was previously detected in only one other cataclysmic variable (CV), MV Lyr. This result reinforces the ubiquity of the linear rms-flux relation as a characteristic property of accretion-induced variability, since it has been observed in several black hole binaries, neutron star binaries and active galactic nuclei. Moreover, its detection in V1504 Cyg is the first time the rms-flux relation has been detected in a dwarf nova-type CV during quiescence. This result, together with previous studies, hence points towards a common physical origin of accretion-induced variability, independent of the size, mass or type of the central accreting compact object.

  20. Time and position resolution of the scintillator strips for a muon system at future colliders

    DOE PAGESBeta

    Denisov, Dmitri; Evdokimov, Valery; Lukic, Strahinja

    2016-03-31

    In this study, prototype scintilator+WLS strips with SiPM readout for a muon system at future colliders were tested for light yield, time resolution and position resolution. Depending on the configuration, light yield of up to 36 photoelectrons per muon per SiPM has been observed, as well as time resolution of 0.45 ns and position resolution along the strip of 7.7 cm.

  1. Time and position resolution of the scintillator strips for a muon system at future colliders

    NASA Astrophysics Data System (ADS)

    Denisov, Dmitri; Evdokimov, Valery; Lukić, Strahinja

    2016-07-01

    Prototype scintilator+WLS strips with SiPM readout for a muon system at future colliders were tested for light yield, time resolution and position resolution. Depending on the configuration, light yield of up to 36 photoelectrons per muon per SiPM has been observed, as well as time resolution of 0.45 ns and position resolution along the strip of 7.7 cm.

  2. Evaluation and design of a small portable EMG amplifier with potential RMS output.

    PubMed

    Shimomura, Y; Iwanaga, K; Harada, H; Katsuura, T

    1999-03-01

    The present study attempted to design and evaluate a small portable electromyogram (EMG) amplifier that can output enhanced EMG and its root mean square (RMS) value. The production and design were of a laboratory scale without any special or high cost circuit construction. The designed amplifier was actually innovated according to the actual working conditions based on physiological anthropology. The present amplifier was compared with commercially available products and proved to be of practical use. The device was installed with a sufficiently small body depicting 8-channel variable gain AC amplifier and variable time-window RMS-to-DC converter. The prototype was battery-driven and well-shielded to minimize external noise interference. PMID:10388160

  3. Universal behavior of the interoccurrence times between losses in financial markets: Independence of the time resolution

    NASA Astrophysics Data System (ADS)

    Ludescher, Josef; Bunde, Armin

    2014-12-01

    We consider representative financial records (stocks and indices) on time scales between one minute and one day, as well as historical monthly data sets, and show that the distribution PQ(r ) of the interoccurrence times r between losses below a negative threshold -Q , for fixed mean interoccurrence times RQ in multiples of the corresponding time resolutions, can be described on all time scales by the same q exponentials, PQ(r ) ∝1 /{[1+(q -1 ) β r ] 1 /(q -1 )} . We propose that the asset- and time-scale-independent analytic form of PQ(r ) can be regarded as an additional stylized fact of the financial markets and represents a nontrivial test for market models. We analyze the distribution PQ(r ) as well as the autocorrelation CQ(s ) of the interoccurrence times for three market models: (i) multiplicative random cascades, (ii) multifractal random walks, and (iii) the generalized autoregressive conditional heteroskedasticity [GARCH(1,1)] model. We find that only one of the considered models, the multifractal random walk model, approximately reproduces the q -exponential form of PQ(r ) and the power-law decay of CQ(s ) .

  4. Measurement of time resolution of thermoregulated SiPM for time of flight detectors

    NASA Astrophysics Data System (ADS)

    Cavazza, D.; D'Antone, I.; Foschi, E.; Guandalini, C.; Lax, I.; Levi, G.; Quadrani, L.; Sbarra, C.; Zuffa, M.

    2012-11-01

    Silicon Photomultipliers (SiPM) are considered very promising in many application where high timing performances, low cost, hardness to radiation damage and single photon counting are requested. Such applications go from astrophysics, high energy accelerator physics to medical physics. A group of SiPM from Hamamatsu has been tested with a low noise fast amplifier based on a hetero-junction FET, mounted on a proper front end board. A first telescope prototype has been used to test the electronics and results are shown. The SiPM time resolution has been measured to be σ∼30 ps, in agreement with other studies reported in literature. The SiPM gain depends critically on temperature and a thermoelectric module to control the circuit was also studied in order to use the system for space detectors.

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

    SciTech Connect

    Nayak, T.K.; Nagamiya, S.; Vossnack, O.; Wu, Y.D.; Zajc, W.A.; Miake, Y.; Ueno, S.; Kitayama, H.; Nagasaka, Y.; Tomizawa, K.; Arai, I.; Yagi, K

    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.

  6. It's time for a crisper image of the Face of the Earth: Landsat and climate time series for massive land cover & climate change mapping at detailed resolution.

    NASA Astrophysics Data System (ADS)

    Pons, Xavier; Miquel, Ninyerola; Oscar, González-Guerrero; Cristina, Cea; Pere, Serra; Alaitz, Zabala; Lluís, Pesquer; Ivette, Serral; Joan, Masó; Cristina, Domingo; Maria, Serra Josep; Jordi, Cristóbal; Chris, Hain; Martha, Anderson; Juanjo, Vidal

    2014-05-01

    Combining climate dynamics and land cover at a relative coarse resolution allows a very interesting approach to global studies, because in many cases these studies are based on a quite high temporal resolution, but they may be limited in large areas like the Mediterranean. However, the current availability of long time series of Landsat imagery and spatially detailed surface climate models allow thinking on global databases improving the results of mapping in areas with a complex history of landscape dynamics, characterized by fragmentation, or areas where relief creates intricate climate patterns that can be hardly monitored or modeled at coarse spatial resolutions. DinaCliVe (supported by the Spanish Government and ERDF, and by the Catalan Government, under grants CGL2012-33927 and SGR2009-1511) is the name of the project that aims analyzing land cover and land use dynamics as well as vegetation stress, with a particular emphasis on droughts, and the role that climate variation may have had in such phenomena. To meet this objective is proposed to design a massive database from long time series of Landsat land cover products (grouped in quinquennia) and monthly climate records (in situ climate data) for the Iberian Peninsula (582,000 km2). The whole area encompasses 47 Landsat WRS2 scenes (Landsat 4 to 8 missions, from path 197 to 202 and from rows 30 to 34), and 52 Landsat WRS1 scenes (for the previous Landsat missions, 212 to 221 and 30 to 34). Therefore, a mean of 49.5 Landsat scenes, 8 quinquennia per scene and a about 6 dates per quinquennium , from 1975 to present, produces around 2376 sets resulting in 30 m x 30 m spatial resolution maps. Each set is composed by highly coherent geometric and radiometric multispectral and multitemporal (to account for phenology) imagery as well as vegetation and wetness indexes, and several derived topographic information (about 10 Tbyte of data). Furthermore, on the basis on a previous work: the Digital Climatic Atlas of

  7. Optimal resolution of a time-dependent aberrationless magnetic lens.

    PubMed

    Calvo, M

    2004-05-01

    We analyse the optimal conditions for operation of a time-dependent magnetic field lens recently proposed. The lens consists of an axially symmetric ellipsoidal coil producing a spatially homogeneous but time-pulsating magnetic field. This system is capable of focusing a beam of charged particles drifting parallel to the coil axis as well as forming images of an object emitting electrons. This lens has no spherical aberration and, consequently, opens the possibility of surpassing the resolving power of conventional round static field lenses. The cardinal elements of this lens are functions of time and thereby the image position, its magnification factor and orientation change in time. We show how by a suitable choice of the magnetic field pulse parameters and the introduction of screens with circular apertures, it is possible to render all the image characteristics stationary. The effect of diffraction is also discussed in the context of transfer function theory. PMID:15093944

  8. Fast timing study of a CeBr3 crystal: Time resolution below 120 ps at 60Co energies

    NASA Astrophysics Data System (ADS)

    Fraile, L. M.; Mach, H.; Vedia, V.; Olaizola, B.; Paziy, V.; Picado, E.; Udías, J. M.

    2013-02-01

    We report on the time response of a novel inorganic scintillator, CeBr3. The measurements were performed using a cylindrical crystal of 1-in. in height and 1-in. in diameter at 22Na and 60Co photon energies. The time response was measured against a fast reference BaF2 detector. Hamamatsu R9779 and Photonis XP20D0 fast photomultipliers (PMTs) were used. The PMT bias voltages and Constant Fraction Discriminator settings were optimized with respect to the timing resolution. The Full Width at Half Maximum (FWHM) time resolution for an individual CeBr3 crystal coupled to Hamamatsu PMT is found here to be as low as 119 ps at 60Co energies, which is comparable to the resolution of 107 ps reported for LaBr3(Ce). For 511 keV photons the measured FWHM time resolution for CeBr3 coupled to the Hamamatsu PMT is 164 ps.

  9. High time-resolution imaging with the MAMA detector systems

    NASA Technical Reports Server (NTRS)

    Morgan, Jeffrey S.; Timothy, J. Gethyn; Smith, Andrew M.; Hill, Bob; Kasle, David B.

    1990-01-01

    Current uses of the MAMA detector which utilize the photon time-tagging capabilities of these detectors are reported. These applications currently include image stabilization by means of post-processing corrections of platform drift and speckle interferometry. The initial results of a sounding rocket experiment to obtain UV images of NGC 6240 and results from speckle interferometry of Neptune's moon Triton are presented.

  10. The lower timing resolution bound for scintillators with non-negligible optical photon transport time in time-of-flight PET

    PubMed Central

    Vinke, Ruud; Olcott, Peter D.; Cates, Joshua W.; Levin, Craig S.

    2014-01-01

    In this work, a method is presented that can calculate the lower bound of the timing resolution for large scintillation crystals with non-negligible photon transport. Hereby, the timing resolution bound can directly be calculated from Monte Carlo generated arrival times of the scintillation photons. This method extends timing resolution bound calculations based on analytical equations, as crystal geometries can be evaluated that do not have closed form solutions of arrival time distributions. The timing resolution bounds are calculated for an exemplary 3 × 3 × 20 mm3 LYSO crystal geometry, with scintillation centers exponentially spread along the crystal length as well as with scintillation centers at fixed distances from the photosensor. Pulse shape simulations further show that analog photosensors intrinsically operate near the timing resolution bound, which can be attributed to the finite single photoelectron pulse rise time. PMID:25255807

  11. Astronaut Richard H. Truly in training session RMS for STS-2 bldg 9A

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Astronaut Richard H. Truly in training session with the Remote Manipulator System (RMS) for STS-2 bldg 9A. Views show Truly working at the command console while watching out the windows. Karen Ehlers, an RMS procedures specialist, can be seen at left side of frame (34314); view from behind Truly as he trains at the RMS console (34315).

  12. Efficient Solar Scene Wavefront Estimation with Reduced Systematic and RMS Errors: Summary

    NASA Astrophysics Data System (ADS)

    Anugu, N.; Garcia, P.

    2016-04-01

    computational efficiency. In the first step, the cross-correlation is implemented at the original image spatial resolution grid (1 pixel). In the second step, the cross-correlation is performed using a sub-pixel level grid by limiting the field of search to 4 × 4 pixels centered at the first step delivered initial position. The generation of these sub-pixel grid based region of interest images is achieved with the bi-cubic interpolation. The correlation matching with sub-pixel grid technique was previously reported in electronic speckle photography Sjö'dahl (1994). This technique is applied here for the solar wavefront sensing. A large dynamic range and a better accuracy in the measurements are achieved with the combination of the original pixel grid based correlation matching in a large field of view and a sub-pixel interpolated image grid based correlation matching within a small field of view. The results revealed that the proposed method outperforms all the different peak-finding algorithms studied in the first approach. It reduces both the systematic error and the RMS error by a factor of 5 (i.e., 75% systematic error reduction), when 5 times improved image sampling was used. This measurement is achieved at the expense of twice the computational cost. With the 5 times improved image sampling, the wave front accuracy is increased by a factor of 5. The proposed solution is strongly recommended for wave front sensing in the solar telescopes, particularly, for measuring large dynamic image shifts involved open loop adaptive optics. Also, by choosing an appropriate increment of image sampling in trade-off between the computational speed limitation and the aimed sub-pixel image shift accuracy, it can be employed in closed loop adaptive optics. The study is extended to three other class of sub-aperture images (a point source; a laser guide star; a Galactic Center extended scene). The results are planned to submit for the Optical Express journal.

  13. The timing resolution of scintillation-detector systems: Monte Carlo analysis.

    PubMed

    Choong, Woon-Seng

    2009-11-01

    Recent advancements in fast scintillating materials and fast photomultiplier tubes (PMTs) have stimulated renewed interest in time-of-flight (TOF) positron emission tomography (PET). It is well known that the improvement in the timing resolution in PET can significantly reduce the noise variance in the reconstructed image resulting in improved image quality. In order to evaluate the timing performance of scintillation detectors used in TOF PET, we use Monte Carlo analysis to model the physical processes (crystal geometry, crystal surface finish, scintillator rise time, scintillator decay time, photoelectron yield, PMT transit time spread, PMT single-electron response, amplifier response and time pick-off method) that can contribute to the timing resolution of scintillation-detector systems. In the Monte Carlo analysis, the photoelectron emissions are modeled by a rate function, which is used to generate the photoelectron time points. The rate function, which is simulated using Geant4, represents the combined intrinsic light emissions of the scintillator and the subsequent light transport through the crystal. The PMT output signal is determined by the superposition of the PMT single-electron response resulting from the photoelectron emissions. The transit time spread and the single-electron gain variation of the PMT are modeled in the analysis. Three practical time pick-off methods are considered in the analysis. Statistically, the best timing resolution is achieved with the first photoelectron timing. The calculated timing resolution suggests that a leading edge discriminator gives better timing performance than a constant fraction discriminator and produces comparable results when a two-threshold or three-threshold discriminator is used. For a typical PMT, the effect of detector noise on the timing resolution is negligible. The calculated timing resolution is found to improve with increasing mean photoelectron yield, decreasing scintillator decay time and

  14. Spectrometer employing optical fiber time delays for frequency resolution

    DOEpatents

    Schuss, Jack J.; Johnson, Larry C.

    1979-01-01

    This invention provides different length glass fibers for providing a broad range of optical time delays for short incident chromatic light pulses for the selective spatial and frequency analysis of the light with a single light detector. To this end, the frequencies of the incident light are orientated and matched with the different length fibers by dispersing the separate frequencies in space according to the respective fiber locations and lengths at the input terminal of the glass fibers. This makes the different length fibers useful in the field of plasma physics. To this end the short light pulses can be scattered by a plasma and then passed through the fibers for analyzing and diagnosing the plasma while it varies rapidly with time.

  15. High time resolution luminosity profiles of Jellyfish (Super) Sprites

    NASA Astrophysics Data System (ADS)

    McHarg, M. G.; Ahrns, J.; Stenbaek-Nielsen, H. C.; Kammae, T.; Haaland, R. K.; Cummer, S. A.; Li, J.; Liu, N.; Yukman, P.

    2011-12-01

    We compare the time history of luminosity and VLF measurements associated with different classes of sprites. In particular we are interested in the larger "jellyfish, or super" sprites that are very bright, very brief duration sprites. Optical observations reveal these sprites are collections of multiple carrot sprites, comprised of both downward and upward propagating streamers. We find the time scales of super sprites are shorter than that for carrot sprites and column sprites. The exponential decrease in sprite luminosity has been related to the conductivity profile assumed for the middle atmosphere by [Barrington-Leigh et. al. (2002), doi: 10.1029/2001JA900117]. We investigate the possibility that the overall brighter and rapid decrease in jellyfish sprite luminosity compared to other types of sprites may be related to changes in the middle atmosphere conductivity, and/or in the driving electrostatic field associated with the causative lightning flash.

  16. High Resolution Space-Time Ozone Modeling for Assessing Trends

    PubMed Central

    Sahu, Sujit K.; Gelfand, Alan E.; Holland, David M.

    2008-01-01

    The assessment of air pollution regulatory programs designed to improve ground level ozone concentrations is a topic of considerable interest to environmental managers. To aid this assessment, it is necessary to model the space-time behavior of ozone for predicting summaries of ozone across spatial domains of interest and for the detection of long-term trends at monitoring sites. These trends, adjusted for the effects of meteorological variables, are needed for determining the effectiveness of pollution control programs in terms of their magnitude and uncertainties across space. This paper proposes a space-time model for daily 8-hour maximum ozone levels to provide input to regulatory activities: detection, evaluation, and analysis of spatial patterns of ozone summaries and temporal trends. The model is applied to analyzing data from the state of Ohio which has been chosen because it contains a mix of urban, suburban, and rural ozone monitoring sites in several large cities separated by large rural areas. The proposed space-time model is auto-regressive and incorporates the most important meteorological variables observed at a collection of ozone monitoring sites as well as at several weather stations where ozone levels have not been observed. This problem of misalignment of ozone and meteorological data is overcome by spatial modeling of the latter. In so doing we adopt an approach based on the successive daily increments in meteorological variables. With regard to modeling, the increment (or change-in-meteorology) process proves more attractive than working directly with the meteorology process, without sacrificing any desired inference. The full model is specified within a Bayesian framework and is fitted using MCMC techniques. Hence, full inference with regard to model unknowns is available as well as for predictions in time and space, evaluation of annual summaries and assessment of trends. PMID:19759840

  17. Large area spark counter with fine time and position resolution

    SciTech Connect

    Ogawa, A.; Fujiwara, N.; Pestov, Yu.N.; Sugahara, R.

    1984-03-01

    The key properties of spark counters include their capability of precision timing (at the sub 100 ps level) and of measuring the position of the charged particle to high accuracy. At SLAC we have undertaken a program to develop these devices for use in high energy physics experiments involving large detectors. A spark counter of size 1.2 m x 0.1 m has been constructed and has been operating continuously in our test setup for several months. Some details of its construction and its properties as a particle detector are reported. 14 references. (WHK)

  18. High Time Resolution Studies of Binary X-Ray Pulsars

    NASA Astrophysics Data System (ADS)

    Cominsky, Lynn R.

    1996-05-01

    The work for this project was substantially more than anticipated, and involved recreating an analysis system for all the HEAO A-1 scanning data which had been converted to the ELE format. As a result of this work, a complete software analysis package was first created at Sonoma State University using Fortran, that can extract the data for any given X-ray source, and produce light curves from the scanning data. A second complete software analysis package was also created, this time in IDL, which can also display all the data in a timely manner, allowing data screening without the generation of hardcopy plots. The creation of the software systems was not the original goal of the project; rather this was a necessary result when the NRL computers became inoperable due to old age and could not be used to support the project, as originally planned. There were 6 sources originally proposed for analysis: SMC X-1, A0538-66, LMC X-1, LMC X-3, (these 3 sources are all located in the Large Magellanic Cloud region), 4UO115+63 and 4U1626-67. Results on these sources are summarized.

  19. Time resolution of time-of-flight detector based on multiple scintillation counters readout by SiPMs

    NASA Astrophysics Data System (ADS)

    Cattaneo, P. W.; De Gerone, M.; Gatti, F.; Nishimura, M.; Ootani, W.; Rossella, M.; Shirabe, S.; Uchiyama, Y.

    2016-08-01

    A new timing detector measuring ∼ 50 MeV / c positrons is under development for the MEG II experiment, aiming at a time resolution σt ∼ 30 ps. The resolution is expected to be achieved by measuring each positron time with multiple counters made of plastic scintillator readout by silicon photomultipliers (SiPMs). The purpose of this work is to demonstrate the time resolution for ∼ 50 MeV / c positrons using prototype counters. Counters with dimensions of 90 × 40 × 5mm3 readout by six SiPMs (three on each 40 × 5mm2 plane) were built with SiPMs from Hamamatsu Photonics and AdvanSiD and tested in a positron beam at the DAΦNE Beam Test Facility. The time resolution was found to improve nearly as the square root of the number of counter hits. A time resolution σt = 26.2 ± 1.3 ps was obtained with eight counters with Hamamatsu SiPMs. These results suggest that the design resolution is achievable in the MEG II experiment.

  20. High resolution heterodyne interferometer based on time-to-digital converter.

    PubMed

    Wang, Fei; Long, Zhangcai; Zhang, Bin; Zhao, Meirong

    2012-04-01

    A new heterodyne interferometer is presented, which adopts time-to-digital converter (TDC) measuring the time intervals of zero crossings of heterodyne signal for phase demodulation. Thanks to the 0.1 ns time resolution of TDC and linear phase demodulation, it can achieve high resolution and avoids nonlinear measuring distortion in other indirect high precise phase demodulation methods, such as pulse width modulation (PWM) and in-phase∕quadrature (I∕Q) method. PMID:22559581

  1. High resolution heterodyne interferometer based on time-to-digital converter

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Long, Zhangcai; Zhang, Bin; Zhao, Meirong

    2012-04-01

    A new heterodyne interferometer is presented, which adopts time-to-digital converter (TDC) measuring the time intervals of zero crossings of heterodyne signal for phase demodulation. Thanks to the 0.1 ns time resolution of TDC and linear phase demodulation, it can achieve high resolution and avoids nonlinear measuring distortion in other indirect high precise phase demodulation methods, such as pulse width modulation (PWM) and in-phase/quadrature (I/Q) method.

  2. Influence of temporal resolution of tracer data on estimates of streamwater transit time distributions

    NASA Astrophysics Data System (ADS)

    Stockinger, Michael; Bogena, Heye; Lücke, Andreas; Diekkrüger, Bernd; Cornelissen, Thomas; Vereecken, Harry

    2016-04-01

    The streamwater transit time distribution (TTD) is often used for a better understanding of a catchment's water storage characteristics and the movement of precipitation water via various flow paths to the stream. Typically, TTDs are estimated by inverse modelling of weekly chemical or stable isotope tracer time series measured in the stream. Few studies used tracer data with a higher temporal resolution. In the present study, we estimated the TTDs for the 42 km² Erkensruhr catchment located in the German low mountain ranges by using weekly and higher temporal resolution of isotope tracer data with the conceptual model TRANSEP. The high resolution data consisted of subdaily precipitation and daily/subdaily streamwater measurements and was aggregated to create the weekly data resolution. Thus, the 1.5 year long time series included base flow as well as event conditions. The high temporal resolution improved the stream isotope simulation compared to the weekly resolution (0.35 vs. 0.24 Nash-Sutcliffe Efficiency), and showed more dynamics in the simulation result. The TTD based on high resolution data was considerably different from the weekly one with a shift towards faster transit times. The mean transit time of water particles was reduced by half (9.5 to 5 years) when applying high resolution data. This indicates that weekly isotopic data lacks information about faster water transport mechanisms in the catchment. Thus, we conclude that high resolution data should be preferred over lower resolution data when estimating TTDs. When comparing TTDs of different catchments, the temporal resolution of the used datasets should be considered.

  3. Quantitative Characterization of Super-Resolution Infrared Imaging Based on Time-Varying Focal Plane Coding

    NASA Astrophysics Data System (ADS)

    Wang, X.; Yuan, Y.; Zhang, J.; Chen, Y.; Cheng, Y.

    2014-10-01

    High resolution infrared image has been the goal of an infrared imaging system. In this paper, a super-resolution infrared imaging method using time-varying coded mask is proposed based on focal plane coding and compressed sensing theory. The basic idea of this method is to set a coded mask on the focal plane of the optical system, and the same scene could be sampled many times repeatedly by using time-varying control coding strategy, the super-resolution image is further reconstructed by sparse optimization algorithm. The results of simulation are quantitatively evaluated by introducing the Peak Signal-to-Noise Ratio (PSNR) and Modulation Transfer Function (MTF), which illustrate that the effect of compressed measurement coefficient r and coded mask resolution m on the reconstructed image quality. Research results show that the proposed method will promote infrared imaging quality effectively, which will be helpful for the practical design of new type of high resolution ! infrared imaging systems.

  4. A cosmic ray test platform based on high time resolution MRPC technology

    NASA Astrophysics Data System (ADS)

    Chen, Tian-Xiang; Li, Cheng; Sun, Yong-Jie; Chen, Hong-Fang; Shao, Ming; Tang, Ze-Bo; Yang, Rong-Xing; Zhou, Yi; Zhang, Yi-Fei

    2015-05-01

    In order to test the performance of detector prototypes in a laboratory environment, we design and build a large area (90 cm×52 cm) test platform for cosmic rays based on a well-designed Multi-gap Resistive Plate Chamber (MRPC) with excellent time resolution and a high detection efficiency for minimum ionizing particles. The time resolution of the MRPC module used is tested to be ∼80 ps, and the position resolution along the strip is ∼5 mm, while the position resolution perpendicular to the strip is ∼12.7 mm. The platform constructed by four MRPC modules can be used for tracking cosmic rays with a spatial resolution of ∼6.3 mm, and provide a reference time ∼40 ps. Supported by National Natural Science Foundation of China (11275196), and Strategic Priority Research Program of the Chinese Academy of Sciences (XDA03010100)

  5. Coherent diffractive imaging of time-evolving samples with improved temporal resolution

    NASA Astrophysics Data System (ADS)

    Ulvestad, A.; Tripathi, A.; Hruszkewycz, S. O.; Cha, W.; Wild, S. M.; Stephenson, G. B.; Fuoss, P. H.

    2016-05-01

    Bragg coherent x-ray diffractive imaging is a powerful technique for investigating dynamic nanoscale processes in nanoparticles immersed in reactive, realistic environments. Its temporal resolution is limited, however, by the oversampling requirements of three-dimensional phase retrieval. Here, we show that incorporating the entire measurement time series, which is typically a continuous physical process, into phase retrieval allows the oversampling requirement at each time step to be reduced, leading to a subsequent improvement in the temporal resolution by a factor of 2-20 times. The increased time resolution will allow imaging of faster dynamics and of radiation-dose-sensitive samples. This approach, which we call "chrono CDI," may find use in improving the time resolution in other imaging techniques.

  6. Active quenching and gating circuit of the photon counting detector for laser time transfer with improved timing resolution and stability

    NASA Astrophysics Data System (ADS)

    Prochazka, Ivan; Blazej, Josef; Kodet, Jan; Michalek, Vojtech

    2015-05-01

    We are presenting the results of research and development of a new active quenching and gating electronics for Single Photon Avalanche Detector (SPAD). The goal of the work was to develop a new SPAD detector package for Laser Time Transfer ground to space with improved timing resolution and stability. The first version of a SPAD detector is operational on board of GNSS navigation satellites. They are based on 25 μm diameter K14 series SPAD chips. They do provide timing resolution of typically 125 ps and stability of the order of 10 ps. The new control electronics provides timing resolution of 25 ps and timing stability and drifts of the order of one picosecond. The device is constructed on a basis of electronics components for which the space qualified equivalents are commercially available. The device construction, tests and results will be presented in detail.

  7. Reaching time resolution of less than 10 ps with plastic scintillation detectors

    NASA Astrophysics Data System (ADS)

    Zhao, J. W.; Sun, B. H.; Tanihata, I.; Terashima, S.; Zhu, L. H.; Enomoto, A.; Nagae, D.; Nishimura, T.; Omika, S.; Ozawa, A.; Takeuchi, Y.; Yamaguchi, T.

    2016-07-01

    Timing-pick up detectors with excellent timing resolutions are essential in many modern nuclear physics experiments. Aiming to develop a Time-Of-Flight system with precision down to about 10 ps, we have made a systematic study of the timing characteristic of TOF detectors, which consist of several combinations of plastic scintillators and photomultiplier tubes. With the conventional electronics, the best timing resolution of about 5.1 ps (σ) has been achieved for detectors with an area size of 3 × 1cm2 . It is found that for data digitalization a combination of TAC and ADC can achieve a better time resolution than the currently available TDC. Simultaneous measurements of both time and pulse height are very valuable for the correction of time-walk effect.

  8. Analytical model of SiPM time resolution and order statistics with crosstalk

    NASA Astrophysics Data System (ADS)

    Vinogradov, S.

    2015-07-01

    Time resolution is the most important parameter of photon detectors in a wide range of time-of-flight and time correlation applications within the areas of high energy physics, medical imaging, and others. Silicon photomultipliers (SiPM) have been initially recognized as perfect photon-number-resolving detectors; now they also provide outstanding results in the scintillator timing resolution. However, crosstalk and afterpulsing introduce false secondary non-Poissonian events, and SiPM time resolution models are experiencing significant difficulties with that. This study presents an attempt to develop an analytical model of the timing resolution of an SiPM taking into account statistics of secondary events resulting from a crosstalk. Two approaches have been utilized to derive an analytical expression for time resolution: the first one based on statistics of independent identically distributed detection event times and the second one based on order statistics of these times. The first approach is found to be more straightforward and "analytical-friendly" to model analog SiPMs. Comparisons of coincidence resolving times predicted by the model with the known experimental results from a LYSO:Ce scintillator and a Hamamatsu MPPC are presented.

  9. Analysis of single-photon time resolution of FBK silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Acerbi, Fabio; Ferri, Alessandro; Gola, Alberto; Zorzi, Nicola; Piemonte, Claudio

    2015-07-01

    We characterized and analyzed an important feature of silicon photomultipliers: the single-photon time resolution (SPTR). We characterized the SPTR of new RGB (Red-Green-Blue) type Silicon Photomultipliers and SPADs produced at FBK (Trento, Italy), studying its main limiting factors. We compared time resolution of 1×1 mm2 and 3×3 mm2 SiPMs and a single SiPM cell (i.e. a SPAD with integrated passive-quenching), employing a mode-locked pulsed laser with 2-ps wide pulses. We estimated the contribution of front-end electronic-noise, of cell-to-cell uniformity, and intrinsic cell time-resolution. At a single-cell level, we compared the results obtained with different layouts. With a circular cell with a top metallization covering part of the edge and enhancing the signal extraction, we reached ~20 ps FWHM of time resolution.

  10. Test and characterisation of SiPMs for the MEGII high resolution Timing Counter

    NASA Astrophysics Data System (ADS)

    Simonetta, M.; Biasotti, M.; Boca, G.; Cattaneo, P. W.; De Gerone, M.; Gatti, F.; Nardò, R.; Nishimura, M.; Ootani, W.; Pizzigoni, G.; Prata, M. C.; Rossella, M.; Shibata, N.; Uchiyama, Y.; Yoshida, K.

    2016-07-01

    The MEGII Timing Counter will measure the positron time of arrival with a resolution of ~ 30 ps relying on two arrays of scintillator pixels read out by 6144 Silicon Photomultipliers (SiPMs) from AdvanSiD. They are characterised, measuring their breakdown voltage, to assure that the gains of the SiPMs of each pixel are as uniform as possible, to maximise the pixel resolution. Gain measurements have also been performed.

  11. 100 ps time resolution with thin silicon pixel detectors and a SiGe HBT amplifier

    NASA Astrophysics Data System (ADS)

    Benoit, M.; Cardarelli, R.; Débieux, S.; Favre, Y.; Iacobucci, G.; Nessi, M.; Paolozzi, L.; Shu, K.

    2016-03-01

    A 100 μm thick silicon detector with 1 mm2 pad readout optimized for sub-nanosecond time resolution has been developed and tested. Coupled to a purposely developed amplifier based on SiGe HBT technology, this detector was characterized at the H8 beam line at the CERN SPS. An excellent time resolution of (106 ± 1) ps for silicon detectors was measured with minimum ionizing particles.

  12. Dependence of Hurricane intensity and structures on vertical resolution and time-step size

    NASA Astrophysics Data System (ADS)

    Zhang, Da-Lin; Wang, Xiaoxue

    2003-09-01

    In view of the growing interests in the explicit modeling of clouds and precipitation, the effects of varying vertical resolution and time-step sizes on the 72-h explicit simulation of Hurricane Andrew (1992) are studied using the Pennsylvania State University/National Center for Atmospheric Research (PSU/NCAR) mesoscale model (i.e., MM5) with the finest grid size of 6 km. It is shown that changing vertical resolution and time-step size has significant effects on hurricane intensity and inner-core cloud/precipitation, but little impact on the hurricane track. In general, increasing vertical resolution tends to produce a deeper storm with lower central pressure and stronger three-dimensional winds, and more precipitation. Similar effects, but to a less extent, occur when the time-step size is reduced. It is found that increasing the low-level vertical resolution is more efficient in intensifying a hurricane, whereas changing the upper-level vertical resolution has little impact on the hurricane intensity. Moreover, the use of a thicker surface layer tends to produce higher maximum surface winds. It is concluded that the use of higher vertical resolution, a thin surface layer, and smaller time-step sizes, along with higher horizontal resolution, is desirable to model more realistically the intensity and inner-core structures and evolution of tropical storms as well as the other convectively driven weather systems.

  13. Post-processing method to reduce noise while preserving high time resolution in aethalometer real-time black carbon data

    EPA Science Inventory

    Real-time aerosol black carbon (BC) data, presented at time resolutions on the order of seconds to minutes, is desirable in field and source characterization studies measuring rapidly varying concentrations of BC. The Optimized Noise-reduction Averaging (ONA) algorithm has been d...

  14. Focal plane resolution and overlapped array time delay and integrate imaging

    NASA Astrophysics Data System (ADS)

    Grycewicz, Thomas J.; Cota, Stephen A.; Lomheim, Terrence S.; Kalman, Linda S.

    2010-06-01

    In this paper we model sub-pixel image registration for a generic earth-observing satellite system with a focal plane using two offset time delay and integrate (TDI) arrays in the focal plane to improve the achievable ground resolution over the resolution achievable with a single array. The modeling process starts with a high-resolution image as ground truth. The Parameterized Image Chain Analysis & Simulation Software (PICASSO) modeling tool is used to degrade the images to match the optical transfer function, sampling, and noise characteristics of the target system. The model outputs a pair of images with a separation close to the nominal half-pixel separation between the overlapped arrays. A registration estimation algorithm is used to measure the offset for image reconstruction. The two images are aligned and summed on a grid with twice the capture resolution. We compare the resolution in images between the inputs before overlap, the reconstructed image, and a simulation for the image which would have been captured on a focal plane with twice the resolution. We find the performance to always be better than the lower resolution baseline, and to approach the performance of the high-resolution array in the ideal case. We show that the overlapped array imager significantly outperforms both the conventional high- and low-resolution imagers in conditions with high image smear.

  15. The RMS survey. 13CO observations of candidate massive YSOs in the northern Galactic plane

    NASA Astrophysics Data System (ADS)

    Urquhart, J. S.; Busfield, A. L.; Hoare, M. G.; Lumsden, S. L.; Oudmaijer, R. D.; Moore, T. J. T.; Gibb, A. G.; Purcell, C. R.; Burton, M. G.; Maréchal, L. J. L.; Jiang, Z.; Wang, M.

    2008-08-01

    Context: The Red MSX Source (RMS) survey is an ongoing multi-wavelength observational programme designed to return a large, high-resolution mid-infrared colour-selected sample of massive young stellar objects (MYSOs). We have identified 2000 MYSO candidates located within our Galaxy by comparing the colours of MSX and 2MASS point sources to those of known MYSOs. The aim of our follow-up observations is to identify other objects with similar colours such as ultra compact (UC) HII regions, evolved stars and planetary nebulae (PNe) and distinguish between genuine MYSOs and nearby low-mass YSOs. Aims: A critical part of our follow-up programme is to conduct 13CO molecular line observations in order to determine kinematic distances to all of our MYSO candidates. These distances will be used in combination with far-IR and (sub)millimetre fluxes to determine bolometric luminosities which will allow us to identify and remove nearby low-mass YSOs. In addition these molecular line observations will help in identifying evolved stars which are weak CO emitters. Methods: We have used the 15 m James Clerk Maxwell Telescope (JCMT), the 13.7 m telescope of the Purple Mountain Observatory (PMO), the 20 m Onsala telescope and the 22 m Mopra telescope to conduct molecular line observations towards 508 MYSOs candidates located in the 1st and 2nd Quadrants. These observations have been made at the J=1-0 (Mopra, Onsala and PMO) and J=2-1 (JCMT) rotational transition frequency of 13CO molecules and have a spatial resolution of 20´´-55´´, a sensitivity of T{A}* ≃ 0.1 K and a velocity resolution of 0.2 km s-1. We complement these targeted observations with 13CO spectra extracted from the Galactic Ring Survey (GRS), which have a velocity resolution of 0.21 km s-1 and sensitivity T{A}* ≃ 0.13-0.2 K, towards a further 403 RMS sources. Results: In this paper we present the results and analysis of the 13CO spectra obtained towards 911 MYSO candidates. We detect 13CO emission towards 780

  16. A demonstration of ultra-high time resolution with a pulse-dilation photo-multiplier

    NASA Astrophysics Data System (ADS)

    Hares, J. D.; Dymoke-Bradshaw, A. K. L.; Hilsabeck, T. J.; Kilkenny, J. D.; Morris, D.; Horsfield, C. J.; Gales, S. G.; Milnes, J.; Herrmann, H. W.; McFee, C.

    2016-05-01

    A novel microchannel plate (MCP) intensified high-speed photo-multiplier tube making use of pulse-dilation[1] has been tested. A ramped photo-cathode voltage followed by a relatively long drift region results in a transit time which is dependent on the photo-electron birth time. This leads to temporal magnification or dilation, so providing an enhancement in time resolution of the optical signal with respect to the electrical signal at the output anode. By this means a time resolution on the order of picoseconds may be realized with a substantially slower oscilloscope. The photo-electron signal is guided from a photo-cathode to an MCP by an axial magnetic field and a short input record length is stretched by a factor up to 40X to yield significantly improved time resolution at the photo-cathode. Results of the first measurements are presented.

  17. Measurement of the RMS Parity Violating Matrix Element in URANIUM-239

    NASA Astrophysics Data System (ADS)

    Zhu, Xianzhou (Joe).

    We report the first determination of the Root -Mean-Square (RMS) parity violating matrix element in a compound nucleus (CN) system, ^{239 }U. The experiment was performed using the intense pulsed epithermal neutron beam available at the Los Alamos Neutron Scattering Center (LANSCE). The helicity dependence of neutron transmission through a spin zero target (^{238}U) is measured for neutron energies from 6 eV to 300 eV. Parity violation is analyzed on 17 p-wave resonances among which five show 2sigma or larger effects. The largest is a 7sigma effect at the 63.5 eV resonance which shows a parity violating asymmetry of p = 2.6%. A likelihood analysis is performed on these 17 parity violating asymmetries, and the RMS parity violating matrix element is determined for the first time to be M = 0.59_sp{-0.25}{+0.50} meV which corresponds to a parity violating spreading width ofGamma^{PV} = (1.0 {+1.7atop -0.8} ) times 10^{-7} {rm eV}.Using statistical nuclear spectroscopy, we are able to relate M to the effective nucleon-nucleon (NN) interaction. The result is | alpha_{p}| ~ (4 {+4atop -2} ) times 10^{-7} where alpha_{p} is the ratio of the parity violating strength to the parity conserving strength in the effective NN interaction. This agrees qualitatively with the estimate of free NN interaction. The consistency of the experimental measurement with expectation suggests that the manifestation of parity violating NN interaction in CN is understood. It is a challenging problem for the theorists to relate the RMS matrix element in the CN to the underlying NN interaction, therefore providing alternative ways to determine the Desplanques -Donoghue-Holstein (DDH) parameters of the NN interaction. The success of the parity violation study also validates the proposed experiment of studying the time reversal symmetry violation utilizing the large enhancement in the CN.

  18. Design and performance of a high spatial resolution, time-of-flight PET detector

    PubMed Central

    Krishnamoorthy, Srilalan; LeGeyt, Benjamin; Werner, Matthew E.; Kaul, Madhuri; Newcomer, F. M.; Karp, Joel S.; Surti, Suleman

    2014-01-01

    This paper describes the design and performance of a high spatial resolution PET detector with time-of-flight capabilities. With an emphasis on high spatial resolution and sensitivity, we initially evaluated the performance of several 1.5 × 1.5 and 2.0 × 2.0 mm2 and 12–15 mm long LYSO crystals read out by several appropriately sized PMTs. Experiments to evaluate the impact of reflector on detector performance were performed and the final detector consisted of a 32 × 32 array of 1.5 × 1.5 × 15 mm3 LYSO crystals packed with a diffuse reflector and read out by a single Hamamatsu 64 channel multi-anode PMT. Such a design made it compact, modular and offered a cost-effective solution to obtaining excellent energy and timing resolution. To minimize the number of readout signals, a compact front-end readout electronics that summed anode signals along each of the orthogonal directions was also developed. Experimental evaluation of detector performance demonstrates clear discrimination of the crystals within the detector. An average energy resolution (FWHM) of 12.7 ± 2.6% and average coincidence timing resolution (FWHM) of 348 ps was measured, demonstrating suitability for use in the development of a high spatial resolution time-of-flight scanner for dedicated breast PET imaging. PMID:25246711

  19. A novel approach for pulse width measurements with a high precision (8 ps RMS) TDC in an FPGA

    NASA Astrophysics Data System (ADS)

    Ugur, C.; Linev, S.; Michel, J.; Schweitzer, T.; Traxler, M.

    2016-01-01

    High precision time measurements are a crucial element in particle identification experiments, which likewise require pulse width information for Time-over-Threshold (ToT) measurements and charge measurements (correlated with pulse width). In almost all of the FPGA-based TDC applications, pulse width measurements are implemented using two of the TDC channels for leading and trailing edge time measurements individually. This method however, requires twice the number of resources. In this paper we present the latest precision improvements in the high precision TDC (8 ps RMS) developed before [1], as well as the novel way of measuring ToT using a single TDC channel, while still achieving high precision (as low as 11.7 ps RMS). The effect of voltage, generated by a DC-DC converter, over the precision is also discussed. Finally, the outcome of the temperature change over the pulse width measurement is shown and a correction method is suggested to limit the degradation.

  20. A new x-ray framing camera with picoseconds time resolution

    NASA Astrophysics Data System (ADS)

    Gou, Yongsheng; Bai, Yonglin; Liu, Baiyu; Bai, Xiaohong; Qin, Junjun; Wang, Bo; Zhu, Bingli; Peng, Xu; Cao, Weiwei

    2015-10-01

    A new method to get a X-ray framing camera with picoseconds time resolution was proposed based on time amplification. Its principle comes from that we use high voltage electrical pulse to get speed dispersion of the photoelectrons pulse first, and then the photoelectrons pulse will be stretched in axial direction by drift area, at the end the photoelectrons pulse after stretched will be framing imaged by a traditional MCP microchannel plate gated framing camera. A model of the camera was built according to this method. Time amplification of the system is about 30, and image magnification of the system is about 0.4. Parameters for designing the camera system were presented after theoretical deriving and model simulation. At last, theoretical time resolution and spatial resolution of the camera were given.

  1. High-sensitivity high-resolution dual-function signal and time digitizer

    NASA Astrophysics Data System (ADS)

    Sarwana, Saad; Gupta, Deepnarayan; Kirichenko, Alex F.; Oku, Takayuki; Otani, Chiko; Sato, Hiromi; Shimizu, Hirohiko M.

    2002-03-01

    We have developed a dual-function high sensitivity/high-resolution digitizer. It consists of a superconducting digital integrated circuit, which can operate both as a time-to-digital converter (TDC) and a flux counting analog-to-digital converter (ADC). The TDC has a 30 ps multihit time resolution. The ADC has been designed with a superconducting quantum interference device based detector for a 1 μA full scale range. This digitizer is extremely useful in many applications, e.g., for time-of-flight measurements, or as a radiation resistant, low-noise, low-power ADC for detector readout.

  2. Joint time-frequency analysis of high-bandwidth low-resolution ISAR imaging systems

    NASA Astrophysics Data System (ADS)

    Ghogomu, Patrick; Testorf, Markus E.

    2003-09-01

    Joint time-frequency analysis is applied to radar imaging problems. Special attention is given to imaging applications, for which the resolution is severely limited due the available bandwidth of the radar signal both in range and cross-range. This includes the detection of landmines as well as foliage penetration radar imaging. Motivated by this type of imaging problem a new joint time-frequency method, the STPDFT algorithm is introduced and compared with existing methods. The performance of all methods is illustrated with synthetic test signals. In addition, preliminary results are presented which demonstrate the performance of joint-time frequency transforms, if applied to low resolution imaging problems.

  3. Measurement of time resolution of the Mu2e LYSO calorimeter prototype

    NASA Astrophysics Data System (ADS)

    Atanov, N.; Baranov, V.; Colao, F.; Cordelli, M.; Corradi, G.; Dané, E.; Davydov, Yu. I.; Flood, K.; Giovannella, S.; Glagolev, V.; Happacher, F.; Hitlin, D. G.; Martini, M.; Miscetti, S.; Miyashita, T.; Morescalchi, L.; Pezzullo, G.; Saputi, A.; Sarra, I.; Soleti, S. R.; Tassielli, G.; Tereshchenko, V.

    2016-03-01

    In this paper we present the time resolution measurements of the Lutetium-Yttrium Oxyorthosilicate (LYSO) calorimeter prototype for the Mu2e experiment. The measurements have been performed using the e- beam of the Beam Test Facility (BTF) in Frascati, Italy in the energy range from 100 to 400 MeV. The calorimeter prototype consisted of twenty five 30 × 30 × 130mm3, LYSO crystals read out by 10 × 10mm2 Hamamatsu Avalanche Photodiodes (APDs). The energy dependence of the measured time resolution can be parametrized as σt(E) = a /√{ E / GeV } ⊕ b, with the stochastic and constant terms a =(51 ± 1) ps and b =(10 ± 4) ps, respectively. This corresponds to the time resolution of (162 ± 4) ps at 100 MeV.

  4. Time-resolved high-resolution electron microscopy of structural stability in MgO clusters

    SciTech Connect

    Kizuka, T.; Tanaka, N.

    1996-12-31

    Structure and stability of atomic clusters have been studied by time-resolved high-resolution electron microscopy (TRHREM). Typical examples are observations of structural fluctuation in gold (Au) clusters supported on silicon oxide films, graphtized carbon films and magnesium oxide (MgO) films. All the observations have been performed on the clusters consisted of single metal element. Structural stability of ceramics clusters, such as metal-oxide, metal-nitride and metal-carbide clusters, has not been observed by TRHREM although the clusters show anomalous structural and functional properties concerning to solid state physics and materials science. In the present study, the behavior of ceramic, magnesium oxide (MgO) clusters is for the first time observed by TRHREM at 1/60 s time resolution and at atomic resolution down to 0.2 nm.

  5. High resolution time of arrival estimation for a cooperative sensor system

    NASA Astrophysics Data System (ADS)

    Morhart, C.; Biebl, E. M.

    2010-09-01

    Distance resolution of cooperative sensors is limited by the signal bandwidth. For the transmission mainly lower frequency bands are used which are more narrowband than classical radar frequencies. To compensate this resolution problem the combination of a pseudo-noise coded pulse compression system with superresolution time of arrival estimation is proposed. Coded pulsecompression allows secure and fast distance measurement in multi-user scenarios which can easily be adapted for data transmission purposes (Morhart and Biebl, 2009). Due to the lack of available signal bandwidth the measurement accuracy degrades especially in multipath scenarios. Superresolution time of arrival algorithms can improve this behaviour by estimating the channel impulse response out of a band-limited channel view. For the given test system the implementation of a MUSIC algorithm permitted a two times better distance resolution as the standard pulse compression.

  6. Measurement of Time Resolution of the Mu2e LYSO Calorimeter Prototype

    SciTech Connect

    Atanov, N.

    2015-09-16

    In this paper we present the time resolution measurements of the LutetiumYttrium Oxyorthosilicate (LYSO) calorimeter prototype for the Mu2e experiment. The measurements have been performed using the e- beam of the Beam Test Facility (BTF) in Frascati, Italy in the energy range from 100 to 400 MeV. The calorimeter prototype consisted of twenty five 30x30x130 mm3, LYSO crystals read out by 10x10 mm2 Hamamatsu Avalanche Photodiodes (APDs). The energy dependence of the measured time resolution can be parametrized as σt(E) = a/pE/GeV⊕b, with the stochastic and constant terms a = (51±1) ps and b = (14 ± 1) ps, respectively. This corresponds to the time resolution of (162 ± 3) ps at 100 MeV.

  7. A high time resolution x-ray diagnostic on the Madison Symmetric Torus

    NASA Astrophysics Data System (ADS)

    DuBois, Ami M.; Lee, John David; Almagri, Abdulgadar F.

    2015-07-01

    A new high time resolution x-ray detector has been installed on the Madison Symmetric Torus (MST) to make measurements around sawtooth events. The detector system is comprised of a silicon avalanche photodiode, a 20 ns Gaussian shaping amplifier, and a 500 MHz digitizer with 14-bit sampling resolution. The fast shaping time diminishes the need to restrict the amount of x-ray flux reaching the detector, limiting the system dead-time. With a much higher time resolution than systems currently in use in high temperature plasma physics experiments, this new detector has the versatility to be used in a variety of discharges with varying flux and the ability to study dynamics on both slow and fast time scales. This paper discusses the new fast x-ray detector recently installed on MST and the improved time resolution capabilities compared to the existing soft and hard x-ray diagnostics. In addition to the detector hardware, improvements to the detector calibration and x-ray pulse identification software, such as additional fitting parameters and a more sophisticated fitting routine are discussed. Finally, initial data taken in both high confinement and standard reversed-field pinch plasma discharges are compared.

  8. A high time resolution x-ray diagnostic on the Madison Symmetric Torus.

    PubMed

    DuBois, Ami M; Lee, John David; Almagri, Abdulgadar F

    2015-07-01

    A new high time resolution x-ray detector has been installed on the Madison Symmetric Torus (MST) to make measurements around sawtooth events. The detector system is comprised of a silicon avalanche photodiode, a 20 ns Gaussian shaping amplifier, and a 500 MHz digitizer with 14-bit sampling resolution. The fast shaping time diminishes the need to restrict the amount of x-ray flux reaching the detector, limiting the system dead-time. With a much higher time resolution than systems currently in use in high temperature plasma physics experiments, this new detector has the versatility to be used in a variety of discharges with varying flux and the ability to study dynamics on both slow and fast time scales. This paper discusses the new fast x-ray detector recently installed on MST and the improved time resolution capabilities compared to the existing soft and hard x-ray diagnostics. In addition to the detector hardware, improvements to the detector calibration and x-ray pulse identification software, such as additional fitting parameters and a more sophisticated fitting routine are discussed. Finally, initial data taken in both high confinement and standard reversed-field pinch plasma discharges are compared. PMID:26233388

  9. Time-resolved serial crystallography captures high-resolution intermediates of photoactive yellow protein

    DOE PAGESBeta

    Tenboer, Jason; Basu, Shibom; Zatsepin, Nadia; Pande, Kanupriya; Milathianaki, Despina; Frank, Matthias; Hunter, Mark; Boutet, Sebastien; Williams, Garth J.; Koglin, Jason E.; et al

    2014-12-05

    We report that serial femtosecond crystallography using ultrashort pulses from X-ray Free Electron Lasers (XFELs) offers the possibility to study light-triggered dynamics of biomolecules. Using microcrystals of the blue light photoreceptor, photoactive yellow protein, as a model system, we present high resolution, time-resolved difference electron density maps of excellent quality with strong features, which allow the determination of structures of reaction intermediates to 1.6 Å resolution. These results open the way to the study of reversible and non-reversible biological reactions on time scales as short as femtoseconds under conditions which maximize the extent of reaction initiation throughout the crystal.

  10. Real-Time Analysis and Visualization for Single-Molecule Based Super-Resolution Microscopy

    PubMed Central

    Kechkar, Adel; Nair, Deepak; Heilemann, Mike; Choquet, Daniel; Sibarita, Jean-Baptiste

    2013-01-01

    Accurate multidimensional localization of isolated fluorescent emitters is a time consuming process in single-molecule based super-resolution microscopy. We demonstrate a functional method for real-time reconstruction with automatic feedback control, without compromising the localization accuracy. Compatible with high frame rates of EM-CCD cameras, it relies on a wavelet segmentation algorithm, together with a mix of CPU/GPU implementation. A combination with Gaussian fitting allows direct access to 3D localization. Automatic feedback control ensures optimal molecule density throughout the acquisition process. With this method, we significantly improve the efficiency and feasibility of localization-based super-resolution microscopy. PMID:23646160

  11. Real-time analysis and visualization for single-molecule based super-resolution microscopy.

    PubMed

    Kechkar, Adel; Nair, Deepak; Heilemann, Mike; Choquet, Daniel; Sibarita, Jean-Baptiste

    2013-01-01

    Accurate multidimensional localization of isolated fluorescent emitters is a time consuming process in single-molecule based super-resolution microscopy. We demonstrate a functional method for real-time reconstruction with automatic feedback control, without compromising the localization accuracy. Compatible with high frame rates of EM-CCD cameras, it relies on a wavelet segmentation algorithm, together with a mix of CPU/GPU implementation. A combination with Gaussian fitting allows direct access to 3D localization. Automatic feedback control ensures optimal molecule density throughout the acquisition process. With this method, we significantly improve the efficiency and feasibility of localization-based super-resolution microscopy. PMID:23646160

  12. Resolution of time-of-flight mass spectrometers evaluated for secondary neutral mass spectrometry

    NASA Astrophysics Data System (ADS)

    Kato, Makoto; Mogami, Akinori; Naito, Motohiro; Ichimura, Shingo; Shimizu, Hazime

    1988-09-01

    Mass resolution of a time-of-flight mass spectrometer with a two-stage electrostatic reflector is calculated for secondary neutral mass spectrometry. The instrument parameters are optimized for energy and space focusing: correcting the flight time difference due to the energy width ΔE of sputtered particles and the spatial width Δs of an ionizing laser beam. The effect of Δs can be compensated by applying an acceleration field to the ionizing region, and the maximum resolution becomes about 1000 for ΔE=10 eV and Δs=1.0 mm.

  13. Acoustic resolution photoacoustic Doppler velocity measurements in fluids using time-domain cross-correlation

    NASA Astrophysics Data System (ADS)

    Brunker, J.; Beard, P.

    2013-03-01

    Blood flow measurements have been demonstrated using the acoustic resolution mode of photoacoustic sensing. This is unlike previous flowmetry methods using the optical resolution mode, which limits the maximum penetration depth to approximately 1mm. Here we describe a pulsed time correlation photoacoustic Doppler technique that is inherently flexible, lending itself to both resolution modes. Doppler time shifts are quantified via cross-correlation of pairs of photoacoustic waveforms generated in moving absorbers using pairs of laser light pulses, and the photoacoustic waves detected using an ultrasound transducer. The acoustic resolution mode is employed by using the transducer focal width, rather than the large illuminated volume, to define the lateral spatial resolution. The use of short laser pulses allows depth-resolved measurements to be obtained with high spatial resolution, offering the prospect of mapping flow within microcirculation. Whilst our previous work has been limited to a non-fluid phantom, we now demonstrate measurements in more realistic blood-mimicking phantoms incorporating fluid suspensions of microspheres flowing along an optically transparent tube. Velocities up to 110 mm/s were measured with accuracies approaching 1% of the known velocities, and resolutions of a few mm/s. The velocity range and resolution are scalable with excitation pulse separation, but the maximum measurable velocity was considerably smaller than the value expected from the detector focal beam width. Measurements were also made for blood flowing at velocities up to 13.5 mm/s. This was for a sample reduced to 5% of the normal haematocrit; increasing the red blood cell concentration limited the maximum measurable velocity so that no results were obtained for concentrations greater than 20% of a physiologically realistic haematocrit. There are several possible causes for this limitation; these include the detector bandwidth and irregularities in the flow pattern. Better

  14. Simulations of the temporal and spatial resolution for a compact time-resolved electron diffractometer

    NASA Astrophysics Data System (ADS)

    Robinson, Matthew S.; Lane, Paul D.; Wann, Derek A.

    2016-02-01

    A novel compact electron gun for use in time-resolved gas electron diffraction experiments has recently been designed and commissioned. In this paper we present and discuss the extensive simulations that were performed to underpin the design in terms of the spatial and temporal qualities of the pulsed electron beam created by the ionisation of a gold photocathode using a femtosecond laser. The response of the electron pulses to a solenoid lens used to focus the electron beam has also been studied. The simulated results show that focussing the electron beam affects the overall spatial and temporal resolution of the experiment in a variety of ways, and that factors that improve the resolution of one parameter can often have a negative effect on the other. A balance must, therefore, be achieved between spatial and temporal resolution. The optimal experimental time resolution for the apparatus is predicted to be 416 fs for studies of gas-phase species, while the predicted spatial resolution of better than 2 nm-1 compares well with traditional time-averaged electron diffraction set-ups.

  15. Real-time high-resolution heterodyne-based measurements of spectral dynamics in fibre lasers

    PubMed Central

    Sugavanam, Srikanth; Fabbri, Simon; Le, Son Thai; Lobach, Ivan; Kablukov, Sergey; Khorev, Serge; Churkin, Dmitry

    2016-01-01

    Conventional tools for measurement of laser spectra (e.g. optical spectrum analysers) capture data averaged over a considerable time period. However, the generation spectrum of many laser types may involve spectral dynamics whose relatively fast time scale is determined by their cavity round trip period, calling for instrumentation featuring both high temporal and spectral resolution. Such real-time spectral characterisation becomes particularly challenging if the laser pulses are long, or they have continuous or quasi-continuous wave radiation components. Here we combine optical heterodyning with a technique of spatio-temporal intensity measurements that allows the characterisation of such complex sources. Fast, round-trip-resolved spectral dynamics of cavity-based systems in real-time are obtained, with temporal resolution of one cavity round trip and frequency resolution defined by its inverse (85 ns and 24 MHz respectively are demonstrated). We also show how under certain conditions for quasi-continuous wave sources, the spectral resolution could be further increased by a factor of 100 by direct extraction of phase information from the heterodyned dynamics or by using double time scales within the spectrogram approach. PMID:26984634

  16. A 2.9 ps equivalent resolution interpolating time counter based on multiple independent coding lines

    NASA Astrophysics Data System (ADS)

    Szplet, R.; Jachna, Z.; Kwiatkowski, P.; Rozyc, K.

    2013-03-01

    We present the design, operation and test results of a time counter that has an equivalent resolution of 2.9 ps, a measurement uncertainty at the level of 6 ps, and a measurement range of 10 s. The time counter has been implemented in a general-purpose reprogrammable device Spartan-6 (Xilinx). To obtain both high precision and wide measurement range the counting of periods of a reference clock is combined with a two-stage interpolation within a single period of the clock signal. The interpolation involves a four-phase clock in the first interpolation stage (FIS) and an equivalent coding line (ECL) in the second interpolation stage (SIS). The ECL is created as a compound of independent discrete time coding lines (TCL). The number of TCLs used to create the virtual ECL has an effect on its resolution. We tested ECLs made from up to 16 TCLs, but the idea may be extended to a larger number of lines. In the presented time counter the coarse resolution of the counting method equal to 2 ns (period of the 500 MHz reference clock) is firstly improved fourfold in the FIS and next even more than 400 times in the SIS. The proposed solution allows us to overcome the technological limitation in achievable resolution and improve the precision of conversion of integrated interpolators based on tapped delay lines.

  17. Pulse Rise Time Characterization of a High Pressure Xenon Gamma Detector for use in Resolution Enhancement

    SciTech Connect

    TROYER, G.L.

    2000-08-25

    High pressure xenon ionization chamber detectors are possible alternatives to traditional thallium doped sodium iodide (NaI(Tl)) and hyperpure germanium as gamma spectrometers in certain applications. Xenon detectors incorporating a Frisch grid exhibit energy resolutions comparable to cadmium/zinc/telluride (CZT) (e.g. 2% {at} 662keV) but with far greater sensitive volumes. The Frisch grid reduces the position dependence of the anode pulse risetimes, but it also increases the detector vibration sensitivity, anode capacitance, voltage requirements and mechanical complexity. We have been investigating the possibility of eliminating the grid electrode in high-pressure xenon detectors and preserving the high energy resolution using electronic risetime compensation methods. A two-electrode cylindrical high pressure xenon gamma detector coupled to time-to-amplitude conversion electronics was used to characterize the pulse rise time of deposited gamma photons. Time discrimination was used to characterize the pulse rise time versus photo peak position and resolution. These data were collected to investigate the effect of pulse rise time compensation on resolution and efficiency.

  18. In vivo dynamic process imaging using real-time optical-resolution photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Shi, Wei; Shao, Peng; Hajireza, Parsin; Forbrich, Alexander; Zemp, Roger J.

    2013-02-01

    The authors demonstrate in vivo dynamic process imaging using a label-free real-time optical-resolution photoacoustic microscope (OR-PAM). This reflection-mode system takes advantage of a 532-nm fiber laser source with a high pulse repetition rate of up to 600 kHz combined with a fast-scanning mirror system. Microvasculature in SCID mouse ears is imaged at near real-time (0.5 fps) for a 1×1 mm2 field of view (FOV) with micron-scale lateral resolution. We also demonstrate imaging of cardiac-induced microhemodynamics in murine microvasculature at real-time frame-rates (30 fps) over a 250×250 μ FOV using real-time C-scan OR-PAM with ability to provide sustained imaging with near real-time feedback for focusing and positioning.

  19. In vivo dynamic process imaging using real-time optical-resolution photoacoustic microscopy.

    PubMed

    Shi, Wei; Shao, Peng; Hajireza, Parsin; Forbrich, Alexander; Zemp, Roger J

    2013-02-01

    The authors demonstrate in vivo dynamic process imaging using a label-free real-time optical-resolution photoacoustic microscope (OR-PAM). This reflection-mode system takes advantage of a 532-nm fiber laser source with a high pulse repetition rate of up to 600 kHz combined with a fast-scanning mirror system. Microvasculature in SCID mouse ears is imaged at near real-time (0.5 fps) for a 1×1 mm2 field of view (FOV) with micron-scale lateral resolution. We also demonstrate imaging of cardiac-induced microhemodynamics in murine microvasculature at real-time frame-rates (30 fps) over a 250×250 μm2 FOV using real-time C-scan OR-PAM with ability to provide sustained imaging with near real-time feedback for focusing and positioning. PMID:23377002

  20. Energy and coincidence time resolution measurements of CdTe detectors for PET

    PubMed Central

    Ariño, G.; Chmeissani, M.; De Lorenzo, G.; Puigdengoles, C.; Cabruja, E.; Calderón, Y.; Kolstein, M.; Macias-Montero, J.G.; Martinez, R.; Mikhaylova, E.; Uzun, D.

    2013-01-01

    We report on the characterization of 2 mm thick CdTe diode detector with Schottky contacts to be employed in a novel conceptual design of PET scanner. Results at −8°C with an applied bias voltage of −1000 V/mm show a 1.2% FWHM energy resolution at 511 keV. Coincidence time resolution has been measured by triggering on the preamplifier output signal to improve the timing resolution of the detector. Results at the same bias and temperature conditions show a FWHM of 6 ns with a minimum acceptance energy of 500 keV. These results show that pixelated CdTe Schottky diode is an excellent candidate for the development of next generation nuclear medical imaging devices such as PET, Compton gamma cameras, and especially PET-MRI hybrid systems when used in a magnetic field immune configuration. PMID:23750177

  1. Fiber-coupled high-speed asynchronous optical sampling with sub-50 fs time resolution.

    PubMed

    Krauss, N; Nast, A; Heinecke, D C; Kölbl, C; Barros, H G; Dekorsy, T

    2015-02-01

    We present a fiber-coupled pump-probe system with a sub-50 fs time resolution and a nanosecond time window, based on high-speed asynchronous optical sampling. By use of a transmission grism pulse compressor, we achieve pump pulses with a pulse duration of 42 fs, an average power of 300 mW and a peak power exceeding 5 kW at a pulse repetition rate of 1 GHz after 6 m of optical fiber. With this system we demonstrate thickness mapping of soft X-ray mirrors at a sub-nm thickness resolution on a cm(2) scan area. In addition, terahertz field generation with resolved spectral components of up to 3.5 THz at a GHz frequency resolution is demonstrated. PMID:25836085

  2. Mapping atomic motions with ultrabright electrons: towards fundamental limits in space-time resolution.

    PubMed

    Manz, Stephanie; Casandruc, Albert; Zhang, Dongfang; Zhong, Yinpeng; Loch, Rolf A; Marx, Alexander; Hasegawa, Taisuke; Liu, Lai Chung; Bayesteh, Shima; Delsim-Hashemi, Hossein; Hoffmann, Matthias; Felber, Matthias; Hachmann, Max; Mayet, Frank; Hirscht, Julian; Keskin, Sercan; Hada, Masaki; Epp, Sascha W; Flöttmann, Klaus; Miller, R J Dwayne

    2015-01-01

    The long held objective of directly observing atomic motions during the defining moments of chemistry has been achieved based on ultrabright electron sources that have given rise to a new field of atomically resolved structural dynamics. This class of experiments requires not only simultaneous sub-atomic spatial resolution with temporal resolution on the 100 femtosecond time scale but also has brightness requirements approaching single shot atomic resolution conditions. The brightness condition is in recognition that chemistry leads generally to irreversible changes in structure during the experimental conditions and that the nanoscale thin samples needed for electron structural probes pose upper limits to the available sample or "film" for atomic movies. Even in the case of reversible systems, the degree of excitation and thermal effects require the brightest sources possible for a given space-time resolution to observe the structural changes above background. Further progress in the field, particularly to the study of biological systems and solution reaction chemistry, requires increased brightness and spatial coherence, as well as an ability to tune the electron scattering cross-section to meet sample constraints. The electron bunch density or intensity depends directly on the magnitude of the extraction field for photoemitted electron sources and electron energy distribution in the transverse and longitudinal planes of electron propagation. This work examines the fundamental limits to optimizing these parameters based on relativistic electron sources using re-bunching cavity concepts that are now capable of achieving 10 femtosecond time scale resolution to capture the fastest nuclear motions. This analysis is given for both diffraction and real space imaging of structural dynamics in which there are several orders of magnitude higher space-time resolution with diffraction methods. The first experimental results from the Relativistic Electron Gun for Atomic

  3. Energy and time resolution of a LYSO matrix prototype for the Mu2e experiment

    SciTech Connect

    Atanov, N.; Baranov, V.; Colao, F.; Cordelli, M.; Corradi, G.; Dane, E.; Davydov, Yu. I.; Flood, K.; Giovannella, S.; Glagolev, V.; Happacher, F.; Hitlin, D. G.; Martini, M.; Miscetti, S.; Miyashita, T.; Morescalchi, L.; Ott, P.; Pezzullo, G.; Saputi, A.; Sarra, I.; Soleti, S. R.; Tassielli, G.; Tereshchenko, V.; Thomas, A.

    2015-09-28

    We have measured the performances of a LYSO crystal matrix prototype tested with electron and photon beams in the energy range 60–450 MeV. Furthermore, this study has been carried out to determine the achievable energy and time resolutions for the calorimeter of the Mu2e experiment.

  4. Energy and time resolution of a LYSO matrix prototype for the Mu2e experiment

    NASA Astrophysics Data System (ADS)

    Atanov, N.; Baranov, V.; Colao, F.; Cordelli, M.; Corradi, G.; Dané, E.; Davydov, Yu. I.; Flood, K.; Giovannella, S.; Glagolev, V.; Happacher, F.; Hitlin, D. G.; Martini, M.; Miscetti, S.; Miyashita, T.; Morescalchi, L.; Ott, P.; Pezzullo, G.; Saputi, A.; Sarra, I.; Soleti, S. R.; Tassielli, G.; Tereshchenko, V.; Thomas, A.

    2016-07-01

    We have measured the performances of a LYSO crystal matrix prototype tested with electron and photon beams in the energy range 60-450 MeV. This study has been carried out to determine the achievable energy and time resolutions for the calorimeter of the Mu2e experiment.

  5. Nanosecond Time-Resolution Study of Gold Nanorod Rotation at the Liquid-Solid Interface.

    PubMed

    Neupane, Bhanu; Chen, Fang; Wei, Yanli; Fang, Ning; Ligler, Frances S; Wang, Gufeng

    2016-07-18

    Early studies showed that the adsorption of nanorods may start from a special "anchored" state, in which the nanorods lose translational motion but retain rotational freedom. Insight into how the anchored nanorods rotate should provide additional dimensions for understanding particle-surface interactions. Based on conventional time-resolution studies, gold nanorods are thought to continuously rotate following initial interactions with negatively charged glass surfaces. However, this nanosecond time-resolution study reveals that the apparent continuous rotation actually consists of numerous fast, intermittent rotations or transitions between a small number of weakly immobilized states, with the particle resting in the immobilized states most of the time. The actual rotation from one immobilized state to the other happens on a 1 ms timescale, that is, approximately 50 times slower than in the bulk solution. PMID:27062216

  6. Precise timing resolution measurements of GSO scintillators with different Ce concentrations combined with silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Okumura, Satoshi; Yamamoto, Seiichi; Yeol Yeom, Jung; Shimura, Naoaki; Ishibashi, Hiroyuki

    2015-10-01

    Ce doped Gd2SiO5 (GSO) is a scintillator which has relatively fast decay time, high density, high light output, and is used for commercial PET systems. However as time-of-flight (TOF) PET systems become more popular in clinical diagnostic, GSO seems less attractive, because its performance is thought to be insufficient for use in TOF-PET application. Although the timing resolution of the GSO combined with photomultiplier tube (PMT) is known to be inappropriate for TOF-PET system, the performance of GSO coupled to silicon photomultipliers (Si-PM) has not been reported to date. In addition, GSO possesses a variety of decay times depending on its Ce concentration. We measured basic performance of GSOs with different Ce concentrations and then coupled them to Si-PMs to measure the precise timing resolution using a high bandwidth digital oscilloscope. The decay time of GSO with 0.4 mol% Ce were longer (63±4 ns) compared with those with 1.0 mol% (40±2 ns) and 1.5 mol% (33±1 ns). With a Si-PM, the photo-peak channels were almost the same for GSOs with 0.4 mol% Ce and those with 1.5 mol% Ce, but the GSO with 1.0 mol% Ce was ~25% higher. Energy resolutions of these three GSOs were ~13% full-width at half-maximum (FWHM) for 662 keV gamma photons without correcting for saturation effects. When coupled to Si-PMs, the timing resolution for GSO with 1.5 mol% Ce (decay time 33 ns) was 549 ps FWHM, almost good enough to use for TOF-PET system. The combination of GSO with 1.5 mol% Ce with Si-PM will be an interesting combination to realize low cost TOF-PET systems.

  7. A high-resolution, four-band SAR testbed with real-time image formation

    SciTech Connect

    Walker, B.; Sander, G.; Thompson, M.; Burns, B.; Fellerhoff, R.; Dubbert, D.

    1996-03-01

    This paper describes the Twin-Otter SAR Testbed developed at Sandia National Laboratories. This SAR is a flexible, adaptable testbed capable of operation on four frequency bands: Ka, Ku, X, and VHF/UHF bands. The SAR features real-time image formation at fine resolution in spotlight and stripmap modes. High-quality images are formed in real time using the overlapped subaperture (OSA) image-formation and phase gradient autofocus (PGA) algorithms.

  8. High-resolution surface-plasmon resonance real-time imaging.

    PubMed

    Vander, R; Lipson, S G

    2009-01-01

    We use surface-plasmon resonance in a silver film to obtain high-resolution real-time images of a transparent dielectric sample in contact with it. A new aspect of the work was the use of radially polarized illumination from a LED at 530 nm to obtain speckle-free images with high spatial resolution along all orientations. The sensitivity to refractive index changes in the sample is estimated to be better than 10(-3), and the modulation transfer function out to spatial frequency 1 microm(-1) was measured. PMID:19109632

  9. Methods of real time high resolution phase detection for use in laser rangefinders

    NASA Astrophysics Data System (ADS)

    Budzyn, Grzegorz; Tkaczyk, Jakub; Podzorny, Tomasz; Rzepka, Janusz

    2014-05-01

    The purpose of this paper is the comparison of two phase measurement methods commonly used in precision rangefinder systems and their suitability to work with high frequency signals. Basic detection circuits for an FFT and an IQ-based methods were proposed and hardware limitations were considered. A set of simulations to assess the behavior of the algorithms in the presence of the noise was performed. An influence of the ADC resolution on the measurement accuracy was also assessed. It is proved that the IQ-based method shows better resilience to signal distortions and puts lower requirements on the ADC circuit thus is better suited for real time high resolution laser rangefinders.

  10. Implementation of high-resolution time-to-digital converter in 8-bit microcontrollers.

    PubMed

    Bengtsson, Lars E

    2012-04-01

    This paper will demonstrate how a time-to-digital converter (TDC) with sub-nanosecond resolution can be implemented into an 8-bit microcontroller using so called "direct" methods. This means that a TDC is created using only five bidirectional digital input-output-pins of a microcontroller and a few passive components (two resistors, a capacitor, and a diode). We will demonstrate how a TDC for the range 1-10 μs is implemented with 0.17 ns resolution. This work will also show how to linearize the output by combining look-up tables and interpolation. PMID:22559576

  11. Implementation of high-resolution time-to-digital converter in 8-bit microcontrollers

    NASA Astrophysics Data System (ADS)

    Bengtsson, Lars E.

    2012-04-01

    This paper will demonstrate how a time-to-digital converter (TDC) with sub-nanosecond resolution can be implemented into an 8-bit microcontroller using so called "direct" methods. This means that a TDC is created using only five bidirectional digital input-output-pins of a microcontroller and a few passive components (two resistors, a capacitor, and a diode). We will demonstrate how a TDC for the range 1-10 μs is implemented with 0.17 ns resolution. This work will also show how to linearize the output by combining look-up tables and interpolation.

  12. Enhancing the resolution of non-stationary seismic data using improved time-frequency spectral modelling

    NASA Astrophysics Data System (ADS)

    Zhou, Huai-lai; Wang, Chang-cheng; Marfurt, Kurt J.; Jiang, Yi-wei; Bi, Jian-xia

    2016-04-01

    Maximizing vertical resolution is a key objective in seismic data processing. Early deconvolution and spectral balancing algorithms assumed that the seismic source wavelet was temporally invariant, or stationary. In practice, seismic scattering and attenuation give rise to non-stationary seismic source wavelets. To address this issue, most conventional time-varying deconvolution wavelet shaping and spectral modelling techniques using the stationary polynomial fitting assume the wavelet to be locally stationary within a small number of overlapping analysis windows while the fitting coefficients are invariant with all the frequencies. In this paper, we show an improvement obtained by modelling smoothly varying spectra of the seismic wavelet using non-stationary polynomial fitting in the time-frequency domain. We first decompose each seismic trace using a generalized S-transform that provides a good time-frequency distribution for the estimation of the time-varying wavelet spectra. We then model the slowly varying source wavelet spectrum at each time sample by a smooth low-order polynomial. Finally, we spectrally balance the modelled wavelet to flatten the seismic response, thereby increasing vertical resolution. We calibrate the algorithm on a simple synthetic and then apply it to a 3-D land survey acquired in western China, showing the value on both vertical slices through seismic amplitude and attribute time slices. Our new algorithm significantly improves the vertical resolution of the seismic signal, while not increasing the noise.

  13. Using high time resolution aerosol and number size distribution measurements to estimate atmospheric extinction.

    PubMed

    Malm, William C; McMeeking, Gavin R; Kreidenweis, Sonia M; Levin, Ezra; Carrico, Christian M; Day, Derek E; Collett, Jeffrey L; Lee, Taehyoung; Sullivan, Amy P; Raja, Suresh

    2009-09-01

    Rocky Mountain National Park is experiencing reduced visibility and changes in ecosystem function due to increasing levels of oxidized and reduced nitrogen. The Rocky Mountain Atmospheric Nitrogen and Sulfur (RoMANS) study was initiated to better understand the origins of sulfur and nitrogen species as well as the complex chemistry occurring during transport from source to receptor. As part of the study, a monitoring program was initiated for two 1-month time periods--one during the spring and the other during late summer/fall. The monitoring program included intensive high time resolution concentration measurements of aerosol number size distribution, inorganic anions, and cations, and 24-hr time resolution of PM2.5 and PM10 mass, sulfate, nitrate, carbon, and soil-related elements concentrations. These data are combined to estimate high time resolution concentrations of PM2.5 and PM10 aerosol mass and fine mass species estimates of ammoniated sulfate, nitrate, and organic and elemental carbon. Hour-by-hour extinction budgets are calculated by using these species concentration estimates and measurements of size distribution and assuming internal and external particle mixtures. Summer extinction was on average about 3 times higher than spring extinction. During spring months, sulfates, nitrates, carbon mass, and PM10 - PM2.5 mass contributed approximately equal amounts of extinction, whereas during the summer months, carbonaceous material extinction was 2-3 times higher than other species. PMID:19785272

  14. An Accurate Timing Alignment Method with Time-to-Digital Converter Linearity Calibration for High-Resolution TOF PET

    PubMed Central

    Li, Hongdi; Wang, Chao; An, Shaohui; Lu, Xingyu; Dong, Yun; Liu, Shitao; Baghaei, Hossain; Zhang, Yuxuan; Ramirez, Rocio; Wong, Wai-Hoi

    2015-01-01

    Accurate PET system timing alignment minimizes the coincidence time window and therefore reduces random events and improves image quality. It is also critical for time-of-flight (TOF) image reconstruction. Here, we use a thin annular cylinder (shell) phantom filled with a radioactive source and located axially and centrally in a PET camera for the timing alignment of a TOF PET system. This timing alignment method involves measuring the time differences between the selected coincidence detector pairs, calibrating the differential and integral nonlinearity of the time-to-digital converter (TDC) with the same raw data and deriving the intrinsic time biases for each detector using an iterative algorithm. The raw time bias for each detector is downloaded to the front-end electronics and the residual fine time bias can be applied during the TOF list-mode reconstruction. Our results showed that a timing alignment accuracy of better than ±25 ps can be achieved, and a preliminary timing resolution of 473 ps (full width at half maximum) was measured in our prototype TOF PET/CT system. PMID:26543243

  15. A Compact Liquid Xenon Compton Telescope with High Energy Resolution and Time-of-Flight

    NASA Astrophysics Data System (ADS)

    Oberlack, Uwe; Gomez, R.; Olsen, C.; Shagin, P.; Aprile, E.; Giboni, K.; Plante, G.; Santorelli, R.

    2006-09-01

    Two recent developments have led us to propose a new type of Compton telescope in compact geometry with time-of-flight, for gamma-ray astronomy in the energy regime of 0.2 - 10 MeV. First, the technology of vacuum ultraviolet photosensors for efficient and fast readout of liquid xenon (LXe) scintillation light has improved dramatically over the last few years, and new developments are underway. A LXe Advanced Compton Telescope would consist of two detector arrays of LXe time projection chambers in compact geometry, with time-of-flight (ToF) between detector modules at a resolution of order 100 ps. Second, the previously achieved moderate energy resolution in LXe, a significant draw-back for gamma-ray line spectroscopy, has been found to be largely due to a strong anti-correlation of ionization and scintillation in LXe. Efficient measurement of both charge and light enables us to improve energy resolution greatly. A factor of three improvement over a previous prototype, LXeGRIT, has already been achieved, and the measured underlying physics indicate the possibility of achievng energy resolution below 1% FWHM at 1 MeV. We are vigorously working on improving light and charge readout to realize this potential in a practical detector. We report on the status and prospects of our current research and development program. This work is supported by NASA grant NNG05WC24G.

  16. Time resolution of the plastic scintillator strips with matrix photomultiplier readout for J-PET tomograph.

    PubMed

    Moskal, P; Rundel, O; Alfs, D; Bednarski, T; Białas, P; Czerwiński, E; Gajos, A; Giergiel, K; Gorgol, M; Jasińska, B; Kamińska, D; Kapłon, Ł; Korcyl, G; Kowalski, P; Kozik, T; Krzemień, W; Kubicz, E; Niedźwiecki, Sz; Pałka, M; Raczyński, L; Rudy, Z; Sharma, N G; Słomski, A; Silarski, M; Strzelecki, A; Wieczorek, A; Wiślicki, W; Witkowski, P; Zieliński, M; Zoń, N

    2016-03-01

    Recent tests of a single module of the Jagiellonian Positron Emission Tomography system (J-PET) consisting of 30 cm long plastic scintillator strips have proven its applicability for the detection of annihilation quanta (0.511 MeV) with a coincidence resolving time (CRT) of 0.266 ns. The achieved resolution is almost by a factor of two better with respect to the current TOF-PET detectors and it can still be improved since, as it is shown in this article, the intrinsic limit of time resolution for the determination of time of the interaction of 0.511 MeV gamma quanta in plastic scintillators is much lower. As the major point of the article, a method allowing to record timestamps of several photons, at two ends of the scintillator strip, by means of matrix of silicon photomultipliers (SiPM) is introduced. As a result of simulations, conducted with the number of SiPM varying from 4 to 42, it is shown that the improvement of timing resolution saturates with the growing number of photomultipliers, and that the [Formula: see text] configuration at two ends allowing to read twenty timestamps, constitutes an optimal solution. The conducted simulations accounted for the emission time distribution, photon transport and absorption inside the scintillator, as well as quantum efficiency and transit time spread of photosensors, and were checked based on the experimental results. Application of the [Formula: see text] matrix of SiPM allows for achieving the coincidence resolving time in positron emission tomography of [Formula: see text]0.170 ns for 15 cm axial field-of-view (AFOV) and [Formula: see text]0.365 ns for 100 cm AFOV. The results open perspectives for construction of a cost-effective TOF-PET scanner with significantly better TOF resolution and larger AFOV with respect to the current TOF-PET modalities. PMID:26895187

  17. Time resolution of the plastic scintillator strips with matrix photomultiplier readout for J-PET tomograph

    NASA Astrophysics Data System (ADS)

    Moskal, P.; Rundel, O.; Alfs, D.; Bednarski, T.; Białas, P.; Czerwiński, E.; Gajos, A.; Giergiel, K.; Gorgol, M.; Jasińska, B.; Kamińska, D.; Kapłon, Ł.; Korcyl, G.; Kowalski, P.; Kozik, T.; Krzemień, W.; Kubicz, E.; Niedźwiecki, Sz; Pałka, M.; Raczyński, L.; Rudy, Z.; Sharma, N. G.; Słomski, A.; Silarski, M.; Strzelecki, A.; Wieczorek, A.; Wiślicki, W.; Witkowski, P.; Zieliński, M.; Zoń, N.

    2016-03-01

    Recent tests of a single module of the Jagiellonian Positron Emission Tomography system (J-PET) consisting of 30 cm long plastic scintillator strips have proven its applicability for the detection of annihilation quanta (0.511 MeV) with a coincidence resolving time (CRT) of 0.266 ns. The achieved resolution is almost by a factor of two better with respect to the current TOF-PET detectors and it can still be improved since, as it is shown in this article, the intrinsic limit of time resolution for the determination of time of the interaction of 0.511 MeV gamma quanta in plastic scintillators is much lower. As the major point of the article, a method allowing to record timestamps of several photons, at two ends of the scintillator strip, by means of matrix of silicon photomultipliers (SiPM) is introduced. As a result of simulations, conducted with the number of SiPM varying from 4 to 42, it is shown that the improvement of timing resolution saturates with the growing number of photomultipliers, and that the 2× 5 configuration at two ends allowing to read twenty timestamps, constitutes an optimal solution. The conducted simulations accounted for the emission time distribution, photon transport and absorption inside the scintillator, as well as quantum efficiency and transit time spread of photosensors, and were checked based on the experimental results. Application of the 2× 5 matrix of SiPM allows for achieving the coincidence resolving time in positron emission tomography of ≈ 0.170 ns for 15 cm axial field-of-view (AFOV) and ≈ 0.365 ns for 100 cm AFOV. The results open perspectives for construction of a cost-effective TOF-PET scanner with significantly better TOF resolution and larger AFOV with respect to the current TOF-PET modalities.

  18. Field-deployable, high-resolution, time-of-flight aerosol mass spectrometer.

    PubMed

    DeCarlo, Peter F; Kimmel, Joel R; Trimborn, Achim; Northway, Megan J; Jayne, John T; Aiken, Allison C; Gonin, Marc; Fuhrer, Katrin; Horvath, Thomas; Docherty, Kenneth S; Worsnop, Doug R; Jimenez, Jose L

    2006-12-15

    The development of a new high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) is reported. The high-resolution capabilities of this instrument allow the direct separation of most ions from inorganic and organic species at the same nominal m/z, the quantification of several types of organic fragments (CxHy, CxHyOz, CxHyNp, CxHyOzNp), and the direct identification of organic nitrogen and organosulfur content. This real-time instrument is field-deployable, and its high time resolution (0.5 Hz has been demonstrated) makes it well-suited for studies in which time resolution is critical, such as aircraft studies. The instrument has two ion optical modes: a single-reflection configuration offers higher sensitivity and lower resolving power (up to approximately 2100 at m/z 200), and a two-reflectron configuration yields higher resolving power (up to approximately 4300 at m/z 200) with lower sensitivity. The instrument also allows the determination of the size distributions of all ions. One-minute detection limits for submicrometer aerosol are <0.04 microg m(-3) for all species in the high-sensitivity mode and <0.4 microg m(-3) in the high-resolution mode. Examples of ambient aerosol data are presented from the SOAR-1 study in Riverside, CA, in which the spectra of ambient organic species are dominated by CxHy and CxHyOz fragments, and different organic and inorganic fragments at the same nominal m/z show different size distributions. Data are also presented from the MIRAGE C-130 aircraft study near Mexico City, showing high correlation with independent measurements of surrogate aerosol mass concentration. PMID:17165817

  19. Remote Manipulator System (RMS)-based Controls-Structures Interaction (CSI) flight experiment feasibility study

    NASA Technical Reports Server (NTRS)

    Demeo, Martha E.

    1990-01-01

    The feasibility of an experiment which will provide an on-orbit validation of Controls-Structures Interaction (CSI) technology, was investigated. The experiment will demonstrate the on-orbit characterization and flexible-body control of large flexible structure dynamics using the shuttle Remote Manipulator System (RMS) with an attached payload as a test article. By utilizing existing hardware as well as establishing integration, operation and safety algorithms, techniques and procedures, the experiment will minimize the costs and risks of implementing a flight experiment. The experiment will also offer spin-off enhancement to both the Shuttle RMS (SRMS) and the Space Station RMS (SSRMS).

  20. Parameters affecting temporal resolution of Time Resolved Integrative Optical Neutron Detector (TRION)

    NASA Astrophysics Data System (ADS)

    Mor, I.; Vartsky, D.; Dangendorf, V.; Bar, D.; Feldman, G.; Goldberg, M. B.; Tittelmeier, K.; Bromberger, B.; Brandis, M.; Weierganz, M.

    2013-11-01

    The Time-Resolved Integrative Optical Neutron (TRION) detector was developed for Fast Neutron Resonance Radiography (FNRR), a fast-neutron transmission imaging method that exploits characteristic energy-variations of the total scattering cross-section in the En = 1-10 MeV range to detect specific elements within a radiographed object. As opposed to classical event-counting time of flight (ECTOF), it integrates the detector signal during a well-defined neutron Time of Flight window corresponding to a pre-selected energy bin, e.g., the energy-interval spanning a cross-section resonance of an element such as C, O and N. The integrative characteristic of the detector permits loss-free operation at very intense, pulsed neutron fluxes, at a cost however, of recorded temporal resolution degradation This work presents a theoretical and experimental evaluation of detector related parameters which affect temporal resolution of the TRION system.

  1. Enhanced focal-resolution of dipole sources using aeroacoustic time-reversal in a wind tunnel

    NASA Astrophysics Data System (ADS)

    Mimani, A.; Moreau, D. J.; Prime, Z.; Doolan, C. J.

    2016-05-01

    This paper presents the first application of the Point-Time-Reversal-Sponge-Layer (PTRSL) damping technique to enhance the focal-resolution of experimental flow-induced dipole sources obtained using the Time-Reversal (TR) source localization method. Experiments were conducted in an Anechoic Wind Tunnel for the case of a full-span cylinder located in a low Mach number cross-flow. The far-field acoustic pressure sampled using two line arrays of microphones located above and below the cylinder exhibited a dominant Aeolian tone. The aeroacoustic TR simulations were implemented using the time-reversed signals whereby the source map revealed the lift-dipole nature at the Aeolian tone frequency. A PTRSL (centred at the predicted dipole location) was shown to reduce the size of dipole focal spots to 7/20th of a wavelength as compared to one wavelength without its use, thereby dramatically enhancing the focal-resolution of the TR technique.

  2. Rapid Diagnosis of Tuberculosis by Real-Time High-Resolution Imaging of Mycobacterium tuberculosis Colonies.

    PubMed

    Ghodbane, Ramzi; Asmar, Shady; Betzner, Marlena; Linet, Marie; Pierquin, Joseph; Raoult, Didier; Drancourt, Michel

    2015-08-01

    Culture remains the cornerstone of diagnosis for pulmonary tuberculosis, but the fastidiousness of Mycobacterium tuberculosis may delay culture-based diagnosis for weeks. We evaluated the performance of real-time high-resolution imaging for the rapid detection of M. tuberculosis colonies growing on a solid medium. A total of 50 clinical specimens, including 42 sputum specimens, 4 stool specimens, 2 bronchoalveolar lavage fluid specimens, and 2 bronchial aspirate fluid specimens were prospectively inoculated into (i) a commercially available Middlebrook broth and evaluated for mycobacterial growth indirectly detected by measuring oxygen consumption (standard protocol) and (ii) a home-made solid medium incubated in an incubator featuring real-time high-resolution imaging of colonies (real-time protocol). Isolates were identified by Ziehl-Neelsen staining and matrix-assisted laser desorption ionization-time of flight mass spectrometry. Use of the standard protocol yielded 14/50 (28%) M. tuberculosis isolates, which is not significantly different from the 13/50 (26%) M. tuberculosis isolates found using the real-time protocol (P = 1.00 by Fisher's exact test), and the contamination rate of 1/50 (2%) was not significantly different from the contamination rate of 2/50 (4%) using the real-time protocol (P = 1.00). The real-time imaging protocol showed a 4.4-fold reduction in time to detection, 82 ± 54 h versus 360 ± 142 h (P < 0.05). These preliminary data give the proof of concept that real-time high-resolution imaging of M. tuberculosis colonies is a new technology that shortens the time to growth detection and the laboratory diagnosis of pulmonary tuberculosis. PMID:26085608

  3. Rapid Diagnosis of Tuberculosis by Real-Time High-Resolution Imaging of Mycobacterium tuberculosis Colonies

    PubMed Central

    Ghodbane, Ramzi; Asmar, Shady; Betzner, Marlena; Linet, Marie; Pierquin, Joseph; Raoult, Didier

    2015-01-01

    Culture remains the cornerstone of diagnosis for pulmonary tuberculosis, but the fastidiousness of Mycobacterium tuberculosis may delay culture-based diagnosis for weeks. We evaluated the performance of real-time high-resolution imaging for the rapid detection of M. tuberculosis colonies growing on a solid medium. A total of 50 clinical specimens, including 42 sputum specimens, 4 stool specimens, 2 bronchoalveolar lavage fluid specimens, and 2 bronchial aspirate fluid specimens were prospectively inoculated into (i) a commercially available Middlebrook broth and evaluated for mycobacterial growth indirectly detected by measuring oxygen consumption (standard protocol) and (ii) a home-made solid medium incubated in an incubator featuring real-time high-resolution imaging of colonies (real-time protocol). Isolates were identified by Ziehl-Neelsen staining and matrix-assisted laser desorption ionization–time of flight mass spectrometry. Use of the standard protocol yielded 14/50 (28%) M. tuberculosis isolates, which is not significantly different from the 13/50 (26%) M. tuberculosis isolates found using the real-time protocol (P = 1.00 by Fisher's exact test), and the contamination rate of 1/50 (2%) was not significantly different from the contamination rate of 2/50 (4%) using the real-time protocol (P = 1.00). The real-time imaging protocol showed a 4.4-fold reduction in time to detection, 82 ± 54 h versus 360 ± 142 h (P < 0.05). These preliminary data give the proof of concept that real-time high-resolution imaging of M. tuberculosis colonies is a new technology that shortens the time to growth detection and the laboratory diagnosis of pulmonary tuberculosis. PMID:26085608

  4. Near-real-time mosaics from high-resolution side-scan sonar

    USGS Publications Warehouse

    Danforth, William W.; O'Brien, Thomas F.; Schwab, W.C.

    1991-01-01

    High-resolution side-scan sonar has proven to be a very effective tool for stuyding and understanding the surficial geology of the seafloor. Since the mid-1970s, the US Geological Survey has used high-resolution side-scan sonar systems for mapping various areas of the continental shelf. However, two problems typically encountered included the short range and the high sampling rate of high-resolution side-scan sonar systems and the acquisition and real-time processing of the enormous volume of sonar data generated by high-resolution suystems. These problems were addressed and overcome in August 1989 when the USGS conducted a side-scan sonar and bottom sampling survey of a 1000-sq-km section of the continental shelf in the Gulf of Farallones located offshore of San Francisco. The primary goal of this survey was to map an area of critical interest for studying continental shelf sediment dynamics. This survey provided an opportunity to test an image processing scheme that enabled production of a side-scan sonar hard-copy mosaic during the cruise in near real-time.

  5. Improving horizontal resolution of high-frequency surface-wave methods using travel-time tomography

    NASA Astrophysics Data System (ADS)

    Yin, Xiaofei; Xu, Hongrui; Wang, Limin; Hu, Yue; Shen, Chao; Sun, Shida

    2016-03-01

    In surface-wave methods, horizontal resolution can be defined as the ability to distinguish anomalous objects that are laterally displaced from each other. The horizontal length of a recognizable geological anomalous body is measured by the lateral variation of shear (S)-wave velocity. Multichannel analysis of surface waves (MASW) is an efficient tool to determine near-surface S-wave velocities. The acquisition of the MASW method involves the same source-receiver configuration moved successively by a fixed distance interval (a few to several stations) along a linear survey line, which is called a roll-along acquisition geometry. A pseudo-2D S-wave velocity section is constructed by aligning 1D models, and each inverted 1D S-wave velocity model reflects the vertical S-wave velocity variation at the midpoint of each geophone spread. Although the MASW method can improve the horizontal resolution of S-wave velocity sections to some degree, the amount of fieldwork is increased by the roll-along acquisition geometry. We propose surface-wave tomography method to investigate horizontal resolution of surface-wave exploration. Phase-velocity dispersion curves are calculated by a pair of traces within a multichannel record through cross-correlation combined with a phase-shift scanning method. Then with the utilization of travel-time tomography, we can obtain high resolution pure-path dispersion curves with diverse sizes of grids at different frequencies. Finally, the pseudo-2D S-wave velocity structure is reconstructed by inverting the pure-path dispersion curves. Travel-time tomography of surface waves can extract accurate dispersion curves from a record with a short receiver spacing, and it can effectively enhance the ability of random noise immunity. Synthetic tests and a real-world example have indicated that travel-time tomography has a great potential for improving the horizontal resolution of surface waves using multi-channel analysis.

  6. The Value of Real-time High Resolution Satellite Precipitation in Capturing Extreme Rainfall Event

    NASA Astrophysics Data System (ADS)

    Imam, B.; Kuranjekar, P.; Behrangi, A.; Hsu, K.; Sorooshian, S.

    2008-05-01

    In many parts of the world, operational real-time flood and hydrologic forecasting are hindered by the lack of reliable real-time precipitation observations. The insufficient ground observations have made satellite-based precipitation estimates the only available source for wide coverage data. As the spatial and temporal resolution of satellite-based rainfall estimates continue to improve, assessing the usefulness of these products, particularly in capturing extreme precipitation events becomes an important issue. This presentation demonstrates and discusses a framework for evaluating real-time high resolution precipitation products in terms of their operational utility. As an example of operational high resolution precipitation products, the 3 hourly near real-time, 0.04°x0.04° Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Cloud Classification System (PERSIANN-CCS) (Hong et. al., 2004) product is compared against gauge and NEXRAD observations of several heavy precipitation events including tropical storm Erin, which affected Texas and Oklahoma during the period of August 10-20, 2007. For each storm, a swath of precipitation along the storm track is analyzed using both real-time and quality controlled versions of the products. Traditional as well as threshold- based (e.g. verification) performance measures are used to describe differences between NEXRAD and Satellite observations' ability to capture severe storm characteristics within the target area and to assess possible shifts in rainfall amount spectrum. While not fully conclusive, the results indicate that for operational purposes, high resolution satellite-based precipitation estimates can fill in a much needed observational gap during severe storm events.

  7. A near-infrared SETI experiment: A multi-time resolution data analysis

    NASA Astrophysics Data System (ADS)

    Tallis, Melisa; Maire, Jerome; Wright, Shelley; Drake, Frank D.; Duenas, Andres; Marcy, Geoffrey W.; Stone, Remington P. S.; Treffers, Richard R.; Werthimer, Dan; NIROSETI

    2016-06-01

    We present new post-processing routines which are used to detect very fast optical and near-infrared pulsed signals using the latest NIROSETI (Near-Infrared Optical Search for Extraterrestrial Intelligence) instrument. NIROSETI was commissioned in 2015 at Lick Observatory and searches for near-infrared (0.95 to 1.65μ) nanosecond pulsed laser signals transmitted by distant civilizations. Traditional optical SETI searches rely on analysis of coincidences that occur between multiple detectors at a fixed time resolution. We present a multi-time resolution data analysis that extends our search from the 1ns to 1ms range. This new feature greatly improves the versatility of the instrument and its search parameters for near-infrared SETI. We aim to use these algorithms to assist us in our search for signals that have varying duty cycles and pulse widths. We tested the fidelity and robustness of our algorithms using both synthetic embedded pulsed signals, as well as data from a near-infrared pulsed laser installed on the instrument. Applications of NIROSETI are widespread in time domain astrophysics, especially for high time resolution transients, and astronomical objects that emit short-duration high-energy pulses such as pulsars.

  8. High resolution time to digital converter for the KM3NeT neutrino telescope

    NASA Astrophysics Data System (ADS)

    Calvo, D.; Real, D.

    2015-01-01

    The KM3NeT collaboration aims at the construction of a multi-km3 high-energy neutrino telescope in the Mediterranean Sea consisting of thousands of glass spheres, each of them containing 31 photomultipliers of small photocathode area. The readout and data acquisition system of KM3NeT has to collect, treat and send to shore, the enormous amount of data produced by the photomultipliers. For this purpose, 31 high-resolution time-interval measuring channels based on time to digital converter are implemented on the field-programmable gate arrays. Architectures with low resources occupancy are desirable allowing the implementation of other instrumentation, communication and synchronization systems on the same device. The required resolution to measure both, time of flight and time-stamp must be 1 ns. A 4-Oversampling technique with two high frequency clocks and an asymmetric FIFO memory is used to achieve this resolution. The proposed firmware has been developed in Xilinx Kintex-7.

  9. Timely Low Resolution SAR Imagery To Support Floodplain Modelling: a Case Study Review

    NASA Astrophysics Data System (ADS)

    di Baldassarre, Giuliano; Schumann, Guy; Brandimarte, Luigia; Bates, Paul

    2011-05-01

    It is widely recognised that remote sensing can support flood monitoring, modelling and management. In particular, satellites carrying Synthetic Aperture Radar (SAR) sensors are valuable as radar wavelengths can penetrate cloud cover and are insensitive to daylight. However, given the strong inverse relationship between spatial resolution and revisit time, monitoring floods from space in near real time is currently only possible through low resolution (about 100 m pixel size) SAR imagery. For instance, ENVISAT-ASAR (Advanced Synthetic Aperture Radar) in WSM (wide swath mode) revisit times are of the order of 3 days and the data can be obtained within 24 h at no (or low) cost. Hence, this type of space-borne data can be used for monitoring major floods on medium-to-large rivers. This paper aims to discuss the potential for, and uncertainties of, coarse resolution SAR imagery to monitor floods and support hydraulic modelling. The paper first describes the potential of globally and freely available space-borne data to support flood inundation modelling in near real time. Then, the uncertainty of SAR-derived flood extent maps is discussed and the need to move from deterministic binary maps (wet/dry) of flood extent to uncertain flood inundation maps is highlighted.

  10. Challengers RMS arm is moved close to the SPAS-01 during proximity operations

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The Shuttle Challenger's remote manipulator system (RMS) arm is moved to within a feet feet of the Shuttle pallet satellite (SPAS-01) during porximity operations. Part of SPAS is obscured by the window edge on the Challenger's flight deck ceiling.

  11. End effector of the Discovery's RMS with tools moves toward Syncom-IV

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The Space Shuttle Discovery's remote manipulator system (RMS) arm and two specially designed extensions move toward the troubled Syncom-IV (LEASAT) communications satellite. Behind it the earth's clouded surface can be seen.

  12. Formula for the rms blur circle radius of Wolter telescope based on aberration theory

    NASA Technical Reports Server (NTRS)

    Shealy, David L.; Saha, Timo T.

    1990-01-01

    A formula for the rms blur circle for Wolter telescopes has been derived using the transverse ray aberration expressions of Saha (1985), Saha (1984), and Saha (1986). The resulting formula for the rms blur circle radius over an image plane and a formula for the surface of best focus based on third-, fifth-, and seventh-order aberration theory predict results in good agreement with exact ray tracing. It has also been shown that one of the two terms in the empirical formula of VanSpeybroeck and Chase (1972), for the rms blur circle radius of a Wolter I telescope can be justified by the aberration theory results. Numerical results are given comparing the rms blur radius and the surface of best focus vs the half-field angle computed by skew ray tracing and from analytical formulas for grazing incidence Wolter I-II telescopes and a normal incidence Cassegrain telescope.

  13. Rms characterization of Bessel Gauss beams: Correspondence between polar and Cartesian representations

    NASA Astrophysics Data System (ADS)

    Rousseau, Guy; Gay, David; Piché, Michel

    2006-09-01

    A recent analysis [G. Rousseau, D. Gay and M. Piché, One-dimensional description of cylindrically symmetric laser beams: application to Bessel-type nondiffracting beams, J. Opt. Soc. Am. A, 22 (2005) 1274] has shown that any cylindrically symmetric laser beam can be synthesized from a single wave called a constituent wave. This representation allows the introduction of one-dimensional Cartesian root-mean-square (rms) parameters to describe the conical structure of cylindrically symmetric laser beams. In this paper, we compare the rms characterization of Bessel-Gauss beams in polar coordinates with that of their respective constituent waves in Cartesian coordinates. Numerical results reveal an asymptotic correspondence between polar and Cartesian rms parameters of Bessel-Gauss beams propagating in a nondiffracting regime. Such a correspondence eliminates misleading interpretations about the propagation factor and the Rayleigh range of nondiffracting Bessel-type beams characterized in terms of polar rms parameters.

  14. Astronaut Anna Fisher practices control of the RMS in a trainer

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Astronaut Anna Lee Fisher, mission specialist for 51-A, practices control of the remote manipulator system (RMS) at a special trainer at JSC. Dr. Fisher is pictured in the manipulator development facility (MDF) of JSC's Shuttle mockup and integration laboratory.

  15. An efficient method for calculating RMS von Mises stress in a random vibration environment

    SciTech Connect

    Segalman, D.J.; Fulcher, C.W.G.; Reese, G.M.; Field, R.V. Jr.

    1998-02-01

    An efficient method is presented for calculation of RMS von Mises stresses from stress component transfer functions and the Fourier representation of random input forces. An efficient implementation of the method calculates the RMS stresses directly from the linear stress and displacement modes. The key relation presented is one suggested in past literature, but does not appear to have been previously exploited in this manner.

  16. An efficient method for calculating RMS von Mises stress in a random vibration environment

    SciTech Connect

    Segalman, D.J.; Fulcher, C.W.G.; Reese, G.M.; Field, R.V. Jr.

    1997-12-01

    An efficient method is presented for calculation of RMS von Mises stresses from stress component transfer functions and the Fourier representation of random input forces. An efficient implementation of the method calculates the RMS stresses directly from the linear stress and displacement modes. The key relation presented is one suggested in past literature, but does not appear to have been previously exploited in this manner.

  17. Particle acceleration due to shocks in the interplanetary field: High time resolution data and simulation results

    NASA Technical Reports Server (NTRS)

    Kessel, R. L.; Armstrong, T. P.; Nuber, R.; Bandle, J.

    1985-01-01

    Data were examined from two experiments aboard the Explorer 50 (IMP 8) spacecraft. The Johns Hopkins University/Applied Lab Charged Particle Measurement Experiment (CPME) provides 10.12 second resolution ion and electron count rates as well as 5.5 minute or longer averages of the same, with data sampled in the ecliptic plane. The high time resolution of the data allows for an explicit, point by point, merging of the magnetic field and particle data and thus a close examination of the pre- and post-shock conditions and particle fluxes associated with large angle oblique shocks in the interplanetary field. A computer simulation has been developed wherein sample particle trajectories, taken from observed fluxes, are allowed to interact with a planar shock either forward or backward in time. One event, the 1974 Day 312 shock, is examined in detail.

  18. A multi-channel high time resolution detector for high content imaging

    NASA Astrophysics Data System (ADS)

    Lapington, J. S.; Fraser, G. W.; Miller, G. M.; Ashton, T. J. R.; Jarron, P.; Despeisse, M.; Powolny, F.; Howorth, J.; Milnes, J.

    2009-10-01

    Medical imaging has long benefited from advances in photon counting detectors arising from space and particle physics. We describe a microchannel plate-based detector system for high content (multi-parametric) analysis, specifically designed to provide a step change in performance and throughput for measurements in imaged live cells and tissue for the 'omics'. The detector system integrates multi-channel, high time resolution, photon counting capability into a single miniaturized detector with integrated ASIC electronics, comprising a fast, low power amplifier discriminator and TDC for every channel of the discrete pixel electronic readout, and achieving a pixel density improvement of order two magnitudes compared with current comparable devices. The device combines high performance, easy reconfigurability, and economy within a compact footprint. We present simulations and preliminary measurements in the context of our ultimate goals of 20 ps time resolution with multi-channel parallel analysis (1024 channels).

  19. Performances of a solid streak camera based on conventional CCD with nanosecond time resolution

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Bai, Yonglin; Zhu, Bingli; Gou, Yongsheng; Xu, Peng; Bai, XiaoHong; Liu, Baiyu; Qin, Junjun

    2015-02-01

    Imaging systems with high temporal resolution are needed to study rapid physical phenomena ranging from shock waves, including extracorporeal shock waves used for surgery, to diagnostics of laser fusion and fuel injection in internal combustion engines. However, conventional streak cameras use a vacuum tube making thus fragile, cumbersome and expensive. Here we report an CMOS streak camera project consists in reproducing completely this streak camera functionality with a single CMOS chip. By changing the mode of charge transfer of CMOS image sensor, fast photoelectric diagnostics of single point with linear CMOS and high-speed line scanning with array CMOS sensor can be achieved respectively. A fast photoelectric diagnostics system has been designed and fabricated to investigate the feasibility of this method. Finally, the dynamic operation of the sensors is exposed. Measurements show a sample time of 500 ps and a time resolution better than 2 ns.

  20. A high time resolution study of the solar wind-magnetosphere energy coupling function

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.; Carbary, J. F.; Meng, C.-I.; Sullivan, J. P.; Lepping, R. P.

    1982-01-01

    A high time resolution study of the relationships between the solar wind-magnetosphere energy coupling function and the total energy dissipation rate of the magnetosphere is made using 5-min average values of solar wind data and of the geomagnetic indices AE and Dst. All the results are essentially the same as those obtained by the earlier studies which were based on the hourly average data set. Therefore, it is confirmed that the magnetosphere is primarily a driven system

  1. A high resolution laser ranging system based on time-correlated single-photon counting technology

    NASA Astrophysics Data System (ADS)

    Yang, Yixin; Wang, Huanqin; Huang, Zhe; Cao, Yangyang; Gui, Huaqiao

    2014-12-01

    Laser ranging has become an important method for both distance measurements and acquisition of threedimensional (3D) images. In this paper, a laser ranging system based on Time-Correlated Single-Photon Counting technology (TCSPC) is developed. A Geiger-mode avalanche photodiode (G-APD), which has the ability of detecting single-photon events, is used to capture the weak light scattered from the long-range target. In order to improve the ranging resolution of TCSPC based measurement system, a high repetition frequency of subnanosecond narrow pulse generator circuit based on the avalanche effect of RF-BJT is designed and applied as the light source. Moreover, some optimized optical light designs have been done to improve the system signal to noise rate (SNR), including using a special aspherical lens as projecting lens, adopting a telephoto camera lens with small view angle and short depth of field before detector. Experimental tests for evaluation of the laser raging system performance are described. As a means of echo signal analysis, three different algorithms have been introduced, in which the cross-correlation algorithm was demonstrated to be the most effective algorithm to determining the round trip time to a target, even based on histograms with a significant amount of background noise photons. It was found that centimeter ranging resolution can be achieved thanks to the use of Time-to-Digital Converter (TDC) with picosecond resolution and the Cross-Correlation algorithm. The proposed laser ranging system has advantages of high range resolution, short response time and simple structure, which was potential applications for 3D object recognition, computer vision, reverse engineering and virtual reality.

  2. Divergence identities in curved space-time a resolution of the stress-energy problem

    NASA Astrophysics Data System (ADS)

    Yilmaz, Hüseyin

    1989-03-01

    It is noted that the joint use of two basic differential identities in curved space-time, namely, 1) the Einstein-Hilbert identity (1915), and 2) the identity of P. Freud (1939), permits a viable alternative to general relativity and a resolution of the "field stress-energy" problem of the gravitational theory. (A tribute to Eugene P. Wigner's 1957 presidential address to the APS)

  3. High time resolution studies of flux transfer events at the Earth's dayside magnetopause using Cluster data

    NASA Astrophysics Data System (ADS)

    Varsani, Ali; Owen, Christopher J.; Fazakerley, Andrew N.; Forsyth, Colin; Walsh, Andrew P.; Andre, Mats; Dandouras, Iannis; Lucek, Elizabeth

    2013-04-01

    Since launch in 2000, the four ESA Cluster spacecraft have each crossed the dayside magnetopause region thousands of times. Many previous studies presenting analysis of data from the mission, have contributed to a better understanding of the structure and dynamics of that interface and its associated boundary layers. While 2D electron pitch angle distributions (PAD) are routinely produced by the PEACE sensors on Cluster at spacecraft spin resolution (4s), the structures in this region are known to undergo changes on faster timescales than this, in response to both external drivers and internal dynamic processes. However, in certain circumstances, near-complete pitch angle distributions can be obtained at higher time resolution using Cluster burst mode data, facilitating a more detailed analysis of the particle behaviour near the magnetopause. In this paper we present an event during which the four spacecraft made outbound crossings through the low latitude boundary layer while the magnetic field orientation allowed a full pitch angle distribution of electrons to be constructed (every 1/8 s). The four Cluster spacecraft were in the 'multi-scale' formation with separations between individual pairs of spacecraft of either ~8000 or ~800 km. During the event in question, the Cluster spacecraft observed two flux transfer events (FTEs) and made a rapid (~16s) crossing of the magnetopause. The first FTE was most prominent in the C1 data a few minutes before the spacecraft crossed the magnetopause; and the second FTE was observed by C2 just before its magnetopause crossing. Additionally, C1 detected the signature associated with the second FTE in the magnetosheath, and the data from C3 show a disturbance in the low latitude boundary layer that also appears to be related to this FTE. We have utilized the high time resolution pitch angle distributions of electrons along with the high time resolution electric & magnetic data and ion distributions, to study in detail the

  4. A Method for Analysing High Resolution, Time Domain, Streak Camera Calibration Data

    SciTech Connect

    Silbernagel, C

    2004-07-02

    Many experiments that require a highly accurate continuous time history of photon emission incorporate streak cameras into their setup. Nonlinear recordings both in time and spatial displacement are inherent to streak camera measurements. These nonlinearities can be attributed to sweep rate electronics, curvature of the electron optics, the magnification, and resolution of the electron optics. These nonlinearities are systematic; it has been shown that a short pulse laser source, an air-spaced etalon of known separation, and a defined spatial resolution mask can provide the proper image information to correct for the resulting distortion. A set of Interactive Data Language (IDL){sup 1} software routines were developed to take a series of calibration images showing temporally and spatially displaced points, and map these points from a nonlinear to a linear space-time resultant function. This correction function, in combination with standardized image correction techniques, can be applied to experiment data to minimize systematic errors and improve temporal and spatial resolution measurements.

  5. High-resolution real-time 3D shape measurement on a portable device

    NASA Astrophysics Data System (ADS)

    Karpinsky, Nikolaus; Hoke, Morgan; Chen, Vincent; Zhang, Song

    2013-09-01

    Recent advances in technology have enabled the acquisition of high-resolution 3D models in real-time though the use of structured light scanning techniques. While these advances are impressive, they require large amounts of computing power, thus being limited to using large desktop computers with high end CPUs and sometimes GPUs. This is undesirable in making high-resolution real-time 3D scanners ubiquitous in our mobile lives. To address this issue, this work describes and demonstrates a real-time 3D scanning system that is realized on a mobile device, namely a laptop computer, which can achieve speeds of 20fps 3D at a resolution of 640x480 per frame. By utilizing a graphics processing unit (GPU) as a multipurpose parallel processor, along with a parallel phase shifting technique, we are able to realize the entire 3D processing pipeline in parallel. To mitigate high speed camera transfer problems, which typically require a dedicated frame grabber, we make use of USB 3.0 along with direct memory access (DMA) to transfer camera images to the GPU. To demonstrate the effectiveness of the technique, we experiment with the scanner on both static geometry of a statue and dynamic geometry of a deforming material sample in front of the system.

  6. Building Change Detection in Very High Resolution Satellite Stereo Image Time Series

    NASA Astrophysics Data System (ADS)

    Tian, J.; Qin, R.; Cerra, D.; Reinartz, P.

    2016-06-01

    There is an increasing demand for robust methods on urban sprawl monitoring. The steadily increasing number of high resolution and multi-view sensors allows producing datasets with high temporal and spatial resolution; however, less effort has been dedicated to employ very high resolution (VHR) satellite image time series (SITS) to monitor the changes in buildings with higher accuracy. In addition, these VHR data are often acquired from different sensors. The objective of this research is to propose a robust time-series data analysis method for VHR stereo imagery. Firstly, the spatial-temporal information of the stereo imagery and the Digital Surface Models (DSMs) generated from them are combined, and building probability maps (BPM) are calculated for all acquisition dates. In the second step, an object-based change analysis is performed based on the derivative features of the BPM sets. The change consistence between object-level and pixel-level are checked to remove any outlier pixels. Results are assessed on six pairs of VHR satellite images acquired within a time span of 7 years. The evaluation results have proved the efficiency of the proposed method.

  7. Efficiency and timing resolution of scintillator tiles read out with silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Pooth, O.; Weingarten, S.; Weinstock, L.

    2016-01-01

    Silicon photomultipliers (SiPM) are semiconductor photo sensors that have the potential to replace photomultiplier tubes (PMT) in various fields of application. We present detectors consisting of 30 × 30 × 0.5 cm3 fast plastic scintillator tiles read out with SiPMs. The detectors offer great electronic and mechanical advantages over the classical PMT-scintillator combination. SiPMs are very compact devices that run independent of magnetic fields at low voltages and no light guides between the scintillator and the SiPM are necessary in the presented layouts. Three prototypes, two of which with integrated wavelength shifting fibres, have been tested in a proton beam at the COSY accelerator at Forschungszentrum Jülich. The different layouts are compared in terms of most probable pulse height, detection efficiency and noise behaviour as well as timing resolution. The spatial distributions of these properties across the scintillator surface are presented. The best layout can be operated at a mean efficiency of bar epsilon=99.9 % while sustaining low noise rates in the order of 10 Hz with a timing resolution of less than 3 ns. Both efficiency and timing resolution show good spatial homogeneity.

  8. A high-resolution, multi-stop, time-to-digital converter for nuclear time-of-flight measurements

    NASA Astrophysics Data System (ADS)

    Spencer, D. F.; Cole, J.; Drigert, M.; Aryaeinejad, R.

    2006-01-01

    A high-resolution, multi-stop, time-to-digital converter (TDC) was designed and developed to precisely measure the times-of-flight (TOF) of incident neutrons responsible for induced fission and capture reactions on actinide targets. The minimum time resolution is ±1 ns. The TDC design was implemented into a single, dual-wide CAMAC module. The CAMAC bus is used for command and control as well as an alternative data output. A high-speed ECL interface, compatible with LeCroy FERA modules, was also provided for the principle data output path. An Actel high-speed field programmable gate array (FPGA) chip was incorporated with an external oscillator and an internal multiple clock phasing system. This device implemented the majority of the high-speed register functions, the state machine for the FERA interface, and the high-speed counting circuit used for the TDC conversion. An external microcontroller was used to monitor and control system-level changes. In this work we discuss the performance of this TDC module as well as its application.

  9. A High Resolution, Multi-stop, Time-to-Digital Converter for Nuclear Time-of-Flight Measurements

    SciTech Connect

    D. F. Spencer; J. Cole; M. Drigert; R. Aryaeinejad

    2006-01-01

    A high-resolution, multi-stop, time-to-digital converter (TDC) was designed and developed to precisely measure the times-of-flight (TOF) of incident neutrons responsible for induced fission and capture reactions on actinide targets. The minimum time resolution is ±1 ns. The TDC design was implemented into a single, dual-wide CAMAC module. The CAMAC bus is used for command and control as well as an alternative data output. A high-speed ECL interface, compatible with LeCroy FERA modules, was also provided for the principle data output path. An Actel high-speed field programmable gate array (FPGA) chip was incorporated with an external oscillator and an internal multiple clock phasing system. This device implemented the majority of the high-speed register functions, the state machine for the FERA interface, and the high-speed counting circuit used for the TDC conversion. An external microcontroller was used to monitor and control system-level changes. In this work we discuss the performance of this TDC module as well as its application.

  10. The RMS survey. 13CO observations of candidate massive YSOs in the southern Galactic plane

    NASA Astrophysics Data System (ADS)

    Urquhart, J. S.; Busfield, A. L.; Hoare, M. G.; Lumsden, S. L.; Oudmaijer, R. D.; Moore, T. J. T.; Gibb, A. G.; Purcell, C. R.; Burton, M. G.; Marechal, L. J. L.

    2007-11-01

    Context: The Red MSX Source (RMS) survey is an ongoing multi-wavelength observational programme designed to return a large, well-selected sample of massive young stellar objects (MYSOs). We have identified 2000 MYSOs candidates located within our Galaxy by comparing the colours of MSX and 2MASS point sources to those of known MYSOs. The aim of our follow-up observations is to identify other contaminating objects such as ultra compact (UC) HII regions, evolved stars and planetary nebulae (PNe) and distinguish between genuine MYSOs and nearby low-mass YSOs. Aims: A critical part of our follow-up programme is to conduct 13CO molecular line observations in order to determine kinematic distances to all of our MYSO candidates. These distances will be used in combination with far-IR and (sub)millimetre fluxes to determine bolometric luminosities which will allow us to identify and remove nearby low-mass YSOs. In addition these molecular line observations will help in identifying evolved stars which are weak CO emitters. Methods: We have used the 22 m Mopra telescope, the 15 m JCMT and the 20 m Onsala telescope to conduct molecular line observations towards 854 MYSOs candidates located in the 3rd and 4th quadrants. These observations have been made at the J = 1-0 (Mopra and Onsala) and J = 2-1 (JCMT) rotational transition frequency of 13CO molecules and have a spatial resolution of 20´´-40´´, a sensitivity of T{A}* ≃ 0.1 K and a velocity resolution of 0.2 km s-1. Results: We detect 13CO emission towards a total of 752 of the 854 RMS sources observed ( 88%). In total 2132 emission components are detected above 3σ level (typically T^*{A} ≥ 0.3 K). Multiple emission profiles are observed towards the majority of these sources - 461 sources ( 60%) - with an average of 4 molecular clouds detected along the line of sight. These multiple emission features make it difficult to assign a kinematic velocity to many of our sample. We have used archival CS (J = 2-1) and maser

  11. In-depth study of single photon time resolution for the Philips digital silicon photomultiplier

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Gundacker, S.; Pizzichemi, M.; Ghezzi, A.; Auffray, E.; Lecoq, P.; Paganoni, M.

    2016-06-01

    The digital silicon photomultiplier (SiPM) has been commercialised by Philips as an innovative technology compared to analog silicon photomultiplier devices. The Philips digital SiPM, has a pair of time to digital converters (TDCs) connected to 12800 single photon avalanche diodes (SPADs). Detailed measurements were performed to understand the low photon time response of the Philips digital SiPM. The single photon time resolution (SPTR) of every single SPAD in a pixel consisting of 3200 SPADs was measured and an average value of 85 ps full width at half maximum (FWHM) was observed. Each SPAD sends the signal to the TDC with different signal propagation time, resulting in a so called trigger network skew. This distribution of the trigger network skew for a pixel (3200 SPADs) has been measured and a variation of 50 ps FWHM was extracted. The SPTR of the whole pixel is the combination of SPAD jitter, trigger network skew, and the SPAD non-uniformity. The SPTR of a complete pixel was 103 ps FWHM at 3.3 V above breakdown voltage. Further, the effect of the crosstalk at a low photon level has been studied, with the two photon time resolution degrading if the events are a combination of detected (true) photons and crosstalk events. Finally, the time response to multiple photons was investigated.

  12. Active imaging lens with real-time variable resolution and constant field of view

    NASA Astrophysics Data System (ADS)

    Parent, Jocelyn; Thibault, Simon

    2010-08-01

    We present a lens with a constant total field of view and real-time variable resolution in certain zones of interest. This smart imaging lens uses an active optical element to modify as desired the local distortion. This way, while keeping the total field of view constant, the resolution can be increased in a zone of interest, at the expense of decreasing it somewhere in the remaining part of the field of view. We first present the concept of this lens, using a deformable mirror as the active surface. Computer simulations are done with Zemax in which a magnifying power of 2 in a zone of interest representing 10% of the full field of view is achieved, using a f=12.5 mm lens and a F/# of 18. Different combinations of theses parameters would allow different performances and results. We then present experimental results of this lens with a prototype built using a ferrofluidic deformable mirror as the active element. Experimental results of a zone of increased resolution with a magnification of 1.32 and a zone of decreased resolution with a magnification of 0.80 are obtained.

  13. Improved-resolution real-time skin-dose mapping for interventional fluoroscopic procedures

    NASA Astrophysics Data System (ADS)

    Rana, Vijay K.; Rudin, Stephen; Bednarek, Daniel R.

    2014-03-01

    We have developed a dose-tracking system (DTS) that provides a real-time display of the skin-dose distribution on a 3D patient graphic during fluoroscopic procedures. Radiation dose to individual points on the skin is calculated using exposure and geometry parameters from the digital bus on a Toshiba C-arm unit. To accurately define the distribution of dose, it is necessary to use a high-resolution patient graphic consisting of a large number of elements. In the original DTS version, the patient graphics were obtained from a library of population body scans which consisted of larger-sized triangular elements resulting in poor congruence between the graphic points and the x-ray beam boundary. To improve the resolution without impacting real-time performance, the number of calculations must be reduced and so we created software-designed human models and modified the DTS to read the graphic as a list of vertices of the triangular elements such that common vertices of adjacent triangles are listed once. Dose is calculated for each vertex point once instead of the number of times that a given vertex appears in multiple triangles. By reformatting the graphic file, we were able to subdivide the triangular elements by a factor of 64 times with an increase in the file size of only 1.3 times. This allows a much greater number of smaller triangular elements and improves resolution of the patient graphic without compromising the real-time performance of the DTS and also gives a smoother graphic display for better visualization of the dose distribution.

  14. Video super-resolution: from QVGA to HD in real-time

    NASA Astrophysics Data System (ADS)

    Mudigoudar, Raj; Bagal, Srinath; Yue, Zhanfeng; Lakshmi, Pramod; Topiwala, Pankaj

    2009-08-01

    In surveillance, reconnaissance and numerous other video applications, enhancing the resolution and quality enhances the usability of captured video. In many such applications, video is often acquired from low cost legacy sensors that offer low resolution due to modest optics and low-resolution arrays, providing imagery that may be grainy and missing important details - and still face transmission bottlenecks. Many post-processing techniques have been proposed to enhance the quality of the video and superresolution is one such technique. In this paper, we extend previous work on a real-time superresolution application implemented in ASIC/FPGA hardware. A gradient based technique is used to register the frames at the sub-pixel level. Once we get the high resolution grid, we use an improved regularization technique in which the image is iteratively modified by applying back-projection to get a sharp and undistorted image. The matlab/simulink proven algorithm was migrated to hardware, to achieve 320x240 -> 1280x960, at more than 38 fps, a stunning superresolution by 16X in total pixels. This significant advance beyond real-time is the main contribution of this paper. Additionally the algorithm is implemented in C to achieve real-time performance in software with optimization for Intel I7 processor. Fixed 32 bit processing structure is used to achieve easy migration across platforms. This gives us a fine balance between the quality and performance. The proposed system is robust and highly efficient. Superresolution greatly decreases camera jitter to deliver a smooth, stabilized, high quality video.

  15. Time-Resolved, Atomic-Resolution Imaging of Metastable Atom Configurations

    NASA Astrophysics Data System (ADS)

    Kisielowski, Christian

    2013-03-01

    In the recent past significant initiatives are dedicated to the exploration of sustainable energy solutions. Certainly, related research must address a rich diversity of challenges because it is not only the static arrangement of matter that must be understood at a single atom level but also the collective behavior of molecular assemblies that leads to functionality. Moreover, hybrid materials are commonly employed that contain hard and soft matter components to artificially stimulate complex behavior. Electron microscopy is often considered a method of choice that may address these challenges if further improved. This paper reports on the development of in-line holography for atomic-resolution electron microscopy, which makes use of dose rates as low as a few atto Amperes per square Ångstrom and of variable acceleration voltages between 20 kV and 300 kV. The approach allows for enhancing resolution in radiation sensitive materials and is especially well suited to study the time evolution of nanoscale objects with single atom sensitivity. For the first time temporary displacements of single atoms from their equilibrium lattice sites into metastable sites across a projected distance of only 0.07 nm and 0.10 nm are directly captured in images with a time resolution around one second. These temporary excitations seem relevant to the irreversible transformation of graphene into carbene and to self-diffusion in catalysts. In suitable experimental conditions, however, atom displacements of 0.05 - 0.1 nm are entirely reversible. Exploiting the reversible nature of such excitations, it may become feasible to probe for conformational object changes in beam sensitive materials at improved spatial resolution. This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231

  16. Automated time-lapse microscopy and high-resolution tracking of cell migration

    SciTech Connect

    Fotos, Joseph S.; Vivek, Patel P.; Karin, Norm J.; Temburni, Murali; Koh, John T.; Galileo, Deni S.

    2006-08-09

    The study of cell motility is greatly enhanced by using a fully-automated high-throughput time-lapse microscopy system that is capable of collecting and analyzing data (1) from closely-spaced time points (seconds to minutes), (2) over long periods (hours to days), (3) from multiple areas of interest, (4) under several different experimental conditions simultaneously. Time-lapse video images collected under phase contrast and fluorescent illumination were analyzed using parameters of migration velocity, total accumulated distance (path length), and directionality for individual cells or for averaged cell populations. Quantitation of ''scratch'' or ''wound healing'' assays revealed unique motility dynamics of drug-treated and adhesion molecule-transfected cells with high resolution and, thus, is a vast distinct improvement of current methods. Several fluorescent vital labeling methods commonly used for end-point analyses, including GFP expression, were evaluated and most were useful for time-lapse studies under specific conditions. For example, fluorescently-labeled tumor cells were seeded onto cell monolayers expressing ectopic adhesion molecules displayed altered migration velocities compared to tumor cells plated directly onto culture dishes. The techniques described here revealed cell motility behavior not discernable by previously-used methods. We propose that quantitative time-lapse video analysis will foster the creation new cell motility assays, and increase the resolution and accuracy of existing assays.

  17. Discrete time interval measurement system: fundamentals, resolution and errors in the measurement of angular vibrations

    NASA Astrophysics Data System (ADS)

    Gómez de León, F. C.; Meroño Pérez, P. A.

    2010-07-01

    The traditional method for measuring the velocity and the angular vibration in the shaft of rotating machines using incremental encoders is based on counting the pulses at given time intervals. This method is generically called the time interval measurement system (TIMS). A variant of this method that we have developed in this work consists of measuring the corresponding time of each pulse from the encoder and sampling the signal by means of an A/D converter as if it were an analog signal, that is to say, in discrete time. For this reason, we have denominated this method as the discrete time interval measurement system (DTIMS). This measurement system provides a substantial improvement in the precision and frequency resolution compared with the traditional method of counting pulses. In addition, this method permits modification of the width of some pulses in order to obtain a mark-phase on every lap. This paper explains the theoretical fundamentals of the DTIMS and its application for measuring the angular vibrations of rotating machines. It also displays the required relationship between the sampling rate of the signal, the number of pulses of the encoder and the rotating velocity in order to obtain the required resolution and to delimit the methodological errors in the measurement.

  18. Estimation of grassland use intensities based on high spatial resolution LAI time series

    NASA Astrophysics Data System (ADS)

    Asam, S.; Klein, D.; Dech, S.

    2015-04-01

    The identification and surveillance of agricultural management and the measurement of biophysical canopy parameters in grasslands is relevant for environmental protection as well as for political and economic reasons, as proper grassland management is partly subsidized. An ideal monitoring tool is remote sensing due to its area wide continuous observations. However, due to small-scaled land use patterns in many parts of central Europe, a high spatial resolution is needed. In this study, the feasibility of RapidEye data to derive leaf area index (LAI) time series and to relate them to grassland management practices is assessed. The study area is the catchment of river Ammer in southern Bavaria, where agricultural areas are mainly grasslands. While extensively managed grasslands are maintained with one to two harvests per year and no or little fertilization, intensive cultivation practices compass three to five harvests per year and turnover pasturing. Based on a RapidEye time series from 2011 with spatial resolution of 6.5 meters, LAI is derived using the inverted radiation transfer model PROSAIL. The LAI in this area ranges from 1.5 to 7.5 over the vegetation period and is estimated with an RMSE between 0.7 and 1.1. The derived LAI maps cover 85 % of the study area's grasslands at least seven times. Using statistical metrics of the LAI time series, different grassland management types can be identified: very intensively managed meadows, intensively managed meadows, intensively managed pastures, and extensively managed meadows and moor. However, a precise identification of the mowing dates highly depends on the coincidence with satellite data acquisitions. Further analysis should focus therefor on the selection of the temporal resolution of the time series as well as on the performance of further vegetation parameters and indices compared to LAI.

  19. High-time resolution measurements of solar wind heavy ions with SOHO/CELIAS/CTOF

    NASA Astrophysics Data System (ADS)

    Janitzek, N. P.; Taut, A.; Berger, L.; Bochsler, P.; Drews, C.; Klecker, B.; Wimmer-Schweingruber, R. F.

    2016-03-01

    The Charge Time-Of-Flight (CTOF) mass spectrometer as part of the Charge, ELement and Isotope Analysis System (CELIAS) onboard the SOlar and Heliospheric Observatory (SOHO) is designed to measure the kinetic properties and elemental/ionic composition of solar wind ions heavier than protons, which we refer to as heavy ions. This is achieved by the combined measurements of the energy-per-charge, the time-of-flight and the energy of incident ions. The CTOF instrument combines a remarkable time-of-flight resolution with a large effective area and a high measurement cadence. This allows to determine the Velocity Distribution Functions (VDFs) of a wide range of heavy ions with 5-minute time resolution which ensures that the complete VDF is measured under nearly identical solar wind and magnetic field conditions. For the measurement period between Day Of Year (DOY) 150 and 220 in 1996, which covers a large part of the instrument's short life time, we analyzed VDFs of solar wind iron Fe8+, Fe9+ and Fe10+ for differential streaming relative to the solar wind proton speed measured simultaneously with the CELIAS Proton Monitor (PM). We find an increasing differential streaming with increasing solar wind proton speed for all investigated ions up to ion-proton velocity differences of 30 - 50 km s-1 at proton velocities of 500 km s-1, which is contradictory to an earlier CTOF study by [7]. We believe this difference is because in this study we used raw Pulse Height Analysis (PHA) data with a significantly increased mass and mass-per-charge resolution compared to the earlier used onboard preprocessed data.

  20. An Error Model for High-Time Resolution Satellite Precipitation Products

    NASA Astrophysics Data System (ADS)

    Maggioni, V.; Sapiano, M.; Adler, R. F.; Huffman, G. J.; Tian, Y.

    2013-12-01

    A new error scheme (PUSH: Precipitation Uncertainties for Satellite Hydrology) is presented to provide global estimates of errors for high time resolution, merged precipitation products. Errors are estimated for the widely used Tropical Rainfall Monitoring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) 3B42 product at daily/0.25° resolution, using the high quality NOAA CPC-UNI gauge analysis as the benchmark. Each of the following four scenarios is explored and explicitly modeled: correct no-precipitation detection (both satellite and gauges detect no precipitation), missed precipitation (satellite records a zero, but it is incorrect), false alarm (satellite detects precipitation, but the reference is zero), and hit (both satellite and gauges detect precipitation). Results over Oklahoma show that the estimated probability distributions are able to reproduce the probability density functions of the benchmark precipitation, in terms of both expected values and quantiles. PUSH adequately captures missed precipitation and false detection uncertainties, reproduces the spatial pattern of the error, and shows a good agreement between observed and estimated errors. The resulting error estimates could be attached to the standard products for the scientific community to use. Investigation is underway to: 1) test the approach in different regions of the world; 2) verify the ability of the model to discern the systematic and random components of the error; 3) and evaluate the model performance when higher time-resolution satellite products (i.e., 3-hourly) are employed.

  1. Ultra-Wideband Time-Difference-of-Arrival High Resolution 3D Proximity Tracking System

    NASA Technical Reports Server (NTRS)

    Ni, Jianjun; Arndt, Dickey; Ngo, Phong; Phan, Chau; Dekome, Kent; Dusl, John

    2010-01-01

    This paper describes a research and development effort for a prototype ultra-wideband (UWB) tracking system that is currently under development at NASA Johnson Space Center (JSC). The system is being studied for use in tracking of lunar./Mars rovers and astronauts during early exploration missions when satellite navigation systems are not available. U IATB impulse radio (UWB-IR) technology is exploited in the design and implementation of the prototype location and tracking system. A three-dimensional (3D) proximity tracking prototype design using commercially available UWB products is proposed to implement the Time-Difference- Of-Arrival (TDOA) tracking methodology in this research effort. The TDOA tracking algorithm is utilized for location estimation in the prototype system, not only to exploit the precise time resolution possible with UWB signals, but also to eliminate the need for synchronization between the transmitter and the receiver. Simulations show that the TDOA algorithm can achieve the fine tracking resolution with low noise TDOA estimates for close-in tracking. Field tests demonstrated that this prototype UWB TDOA High Resolution 3D Proximity Tracking System is feasible for providing positioning-awareness information in a 3D space to a robotic control system. This 3D tracking system is developed for a robotic control system in a facility called "Moonyard" at Honeywell Defense & System in Arizona under a Space Act Agreement.

  2. Temperature-resolution anomalies in the reconstruction of time dynamics from energy-loss experiments

    NASA Astrophysics Data System (ADS)

    Kogar, Anshul; Vig, Sean; Gan, Yu; Abbamonte, Peter

    2014-06-01

    Inelastic scattering techniques provide a powerful approach to studying electron and nuclear dynamics, via reconstruction of a propagator that quantifies the time evolution of a system. There is now growing interest in applying such methods to very low energy excitations, such as lattice vibrations, but in this limit the cross section is no longer proportional to a propagator. Significant deviations occur due to the finite temperature Bose statistics of the excitations. Here we consider this issue in the context of high-resolution electron energy-loss experiments on the copper-oxide superconductor Bi2Sr2CaCu2O8. We find that simple division of a Bose factor yields an accurate propagator on energy scales greater than the resolution width. However, at low energy scales, the effects of resolution and finite temperature conspire to create anomalies in the dynamics at long times. We compare two practical ways for dealing with such anomalies, and discuss the range of validity of the technique in light of this comparison.

  3. Enabling high grayscale resolution displays and accurate response time measurements on conventional computers.

    PubMed

    Li, Xiangrui; Lu, Zhong-Lin

    2012-01-01

    Display systems based on conventional computer graphics cards are capable of generating images with 8-bit gray level resolution. However, most experiments in vision research require displays with more than 12 bits of luminance resolution. Several solutions are available. Bit++ (1) and DataPixx (2) use the Digital Visual Interface (DVI) output from graphics cards and high resolution (14 or 16-bit) digital-to-analog converters to drive analog display devices. The VideoSwitcher (3) described here combines analog video signals from the red and blue channels of graphics cards with different weights using a passive resister network (4) and an active circuit to deliver identical video signals to the three channels of color monitors. The method provides an inexpensive way to enable high-resolution monochromatic displays using conventional graphics cards and analog monitors. It can also provide trigger signals that can be used to mark stimulus onsets, making it easy to synchronize visual displays with physiological recordings or response time measurements. Although computer keyboards and mice are frequently used in measuring response times (RT), the accuracy of these measurements is quite low. The RTbox is a specialized hardware and software solution for accurate RT measurements. Connected to the host computer through a USB connection, the driver of the RTbox is compatible with all conventional operating systems. It uses a microprocessor and high-resolution clock to record the identities and timing of button events, which are buffered until the host computer retrieves them. The recorded button events are not affected by potential timing uncertainties or biases associated with data transmission and processing in the host computer. The asynchronous storage greatly simplifies the design of user programs. Several methods are available to synchronize the clocks of the RTbox and the host computer. The RTbox can also receive external triggers and be used to measure RT with respect

  4. Improving resolution of crosswell seismic section based on time-frequency analysis

    SciTech Connect

    Luo, H.; Li, Y.

    1994-12-31

    According to signal theory, to improve resolution of seismic section is to extend high-frequency band of seismic signal. In cross-well section, sonic log can be regarded as a reliable source providing high-frequency information to the trace near the borehole. In such case, what to do is to introduce this high-frequency information into the whole section. However, neither traditional deconvolution algorithms nor some new inversion methods such as BCI (Broad Constraint Inversion) are satisfied because of high-frequency noise and nonuniqueness of inversion results respectively. To overcome their disadvantages, this paper presents a new algorithm based on Time-Frequency Analysis (TFA) technology which has been increasingly received much attention as an useful signal analysis too. Practical applications show that the new method is a stable scheme to improve resolution of cross-well seismic section greatly without decreasing Signal to Noise Ratio (SNR).

  5. Time-series analysis of high-resolution ebullition fluxes from a stratified, freshwater lake

    NASA Astrophysics Data System (ADS)

    Varadharajan, Charuleka; Hemond, Harold F.

    2012-06-01

    Freshwater lakes can emit significant quantities of methane to the atmosphere by bubbling. The high spatial and temporal heterogeneity of ebullition, combined with a lack of high-resolution field measurements, has made it difficult to accurately estimate methane fluxes or determine the underlying mechanisms for bubble release. We use a high-temporal resolution data set of ebullitive fluxes from the eutrophic Upper Mystic Lake, Massachusetts to understand the triggers that lead to bubbling from submerged sediments. A wavelet approach is introduced to detect ebullition events for multiple time-scales, and is complemented with traditional statistical methods for data analyses. We show that bubble release from lake sediments occurred synchronously at several sites, and was closely associated with small, aperiodic drops in total hydrostatic pressure. Such results are essential to constrain mechanistic models and to design future measurement schemes, particularly with respect to the temporal scales that are needed to accurately observe and quantify ebullition in aquatic ecosystems.

  6. High-resolution distributed temperature sensing with the multiphoton-timing technique

    NASA Astrophysics Data System (ADS)

    Höbel, M.; Ricka, J.; Wüthrich, M.; Binkert, Th.

    1995-06-01

    We report on a multiphoton-timing distributed temperature sensor (DTS) based on the concept of distributed anti-Stokes Raman thermometry. The sensor combines the advantage of very high spatial resolution (40 cm) with moderate measurement times. In 5 min it is possible to determine the temperature of as many as 4000 points along an optical fiber with an accuracy Delta T less than 2 deg C. The new feature of the DTS system is the combination of a fast single-photon avalanche diode with specially designed real-time signal-processing electronics. We discuss various parameters that affect the operation of analog and photon-timing DTS systems. Particular emphasis is put on the consequences of the nonideal behavior of sensor components and the corresponding correction procedures.

  7. Time-reversed ultrasonically encoded optical focusing using two ultrasonic transducers for improved ultrasonic axial resolution

    PubMed Central

    Yang, Qiang; Xu, Xiao; Lai, Puxiang; Xu, Daxiong

    2013-01-01

    Abstract. Focusing light inside highly scattering media is a challenging task in biomedical optical imaging, manipulation, and therapy. A recent invention has overcome this challenge by time reversing ultrasonically encoded diffuse light to an ultrasound-modulated volume inside a turbid medium. In this technique, a photorefractive (PR) crystal or polymer can be used as the phase conjugate mirror for optical time reversal. Accordingly, a relatively long ultrasound burst, whose duration matches the PR response time of the PR material, is usually used to encode the diffuse light. This long burst results in poor focusing resolution along the acoustic axis. In this work, we propose to use two intersecting ultrasound beams, emitted from two ultrasonic transducers at different frequencies, to modulate the diffuse light at the beat frequency within the intersection volume. We show that the time reversal of the light encoded at the beat frequency can converge back to the intersection volume. Experimentally, an acoustic axial resolution of ∼1.1  mm was demonstrated inside turbid media, agreeing with theoretical estimation. PMID:24194060

  8. The Crab pulsar in the visible and ultraviolet with 20 microsecond effective time resolution

    NASA Technical Reports Server (NTRS)

    Percival, J. W.; Biggs, J. D.; Dolan, J. F.; Robinson, E. L.; Taylor, M. J.; Bless, R. C.; Elliot, J. L.; Nelson, M. J.; Ramseyer, T. F.; Van Citters, G. W.

    1993-01-01

    Observations of PSR 0531+21 with the High Speed Photometer on the HST in the visible in October 1991 and in the UV in January 1992 are presented. The time resolution of the instrument was 10.74 microsec; the effective time resolution of the light curves folded modulo the pulsar period was 21.5 microsec. The main pulse arrival time is the same in the UV as in the visible and radio to within the accuracy of the establishment of the spacecraft clock, +/- 1.05 ms. The peak of the main pulse is resolved in time. Corrected for reddening, the intensity spectral index of the Crab pulsar from 1680 to 7400 A is 0.11 +/- 0.13. The pulsed flux has an intensity less than 0.9 percent of the peak flux just before the onset of the main pulse. The variations in intensity of individual main and secondary pulses are uncorrelated, even within the same rotational period.

  9. On high time-range resolution observations of PMSE: Statistical characteristics

    NASA Astrophysics Data System (ADS)

    Sommer, Svenja; Chau, Jorge L.; Schult, Carsten

    2016-06-01

    We present observations of polar mesospheric summer echoes (PMSE) with an unprecedented temporal sampling of 2 ms and range resolution down to 75 m. On these time and spatial scales, PMSE exhibit features, like correlation in time and range, that have not been described before. To characterize our high resolution observations, we provide a 4-D statistical model, based on random processes. In this way we can distinguish between geophysical and instrumental effects on our measurements. In our simulations, PMSE is statistically characterized in frequency, angular space, and inverse altitude. With this model, we are able to reproduce our observations on a statistical basis and estimate the intrinsic spectral width of PMSE. For chosen data sets, such values range between 0.5 Hz and 4 Hz (1.4 ms-1 to 11.2 ms-1). Furthermore, we show that apparent oscillations in time and an apparent high speed motion of the mean scattering center are just representations of the random nature of PMSE measurements on short time scales.

  10. NMDB: real-time database for high resolution neutron monitor measurements

    NASA Astrophysics Data System (ADS)

    Steigies, Christian

    The worldwide network of standardized neutron monitors is, after 50 years, still the stateof-the-art instrumentation to measure variations of the primary cosmic rays in the energy range 500 MeV-60 GeV. These measurements are an ideal complement to space based cosmic ray measurements. Unlike data from satellite experiments, neutron monitor data has never been available in high time resolution from many neutron monitor stations in real-time. The data is often available only from the individual station's website, in varying formats, and not in real-time. To overcome this deficit, the European Commission is supporting the Neutron Monitor database (NMDB) since January 2008 as an e-Infrastructures project in the Seventh Framework Programme in the Capacities section. Neutron Monitor stations that do not yet have 1-minute resolution will be supported by software and the development of an affordable standard registration system to submit the measurements to the database via internet in realtime. This resolves the problem of different data formats and for the first time allows use of realtime cosmic ray measurements for space weather applications. Besides creating a database and developing applications that use this data, a part of the project is dedicated to create a public outreach website to inform about cosmic rays and possible effects on humans, technological systems, and the environment.

  11. Multi-stage shifter for subsecond time resolution of emulsion gamma-ray telescopes

    NASA Astrophysics Data System (ADS)

    Rokujo, H.; Aoki, S.; Takahashi, S.; Kamada, K.; Mizutani, S.; Nakagawa, R.; Ozaki, K.

    2013-02-01

    To observe gamma-ray sources precisely, a balloon-borne experiment with a new type of detector, the emulsion gamma-ray telescope, is planned. A multi-stage shifter mechanism based on the concept of an analog clock serves as a time stamper with subsecond time resolution and uses multiple moving stages mounted on the emulsion chambers. This new technique was employed in a test experiment using a small-scale model in a short-duration balloon flight. Tracks recorded in nuclear emulsion were read by a fully automated scanning system, were reconstructed, and time information were assigned by analysis of their position displacements in the shifter layers. The estimated time resolution was 0.06-0.15 s. The number of tracks passing through the detector was counted every second, and hadron jets were detected as significant excesses observed in the counting rate. In future, the multi-stage shifter is greatly contributing to ongoing efforts to increase the effective area of emulsion gamma-ray telescopes.

  12. Automated time-lapse microscopy and high-resolution tracking of cell migration.

    PubMed

    Fotos, Joseph S; Patel, Vivek P; Karin, Norman J; Temburni, Murali K; Koh, John T; Galileo, Deni S

    2006-05-01

    We describe a novel fully automated high-throughput time-lapse microscopy system and evaluate its performance for precisely tracking the motility of several glioma and osteoblastic cell lines. Use of this system revealed cell motility behavior not discernable with conventional techniques by collecting data (1) from closely spaced time points (minutes), (2) over long periods (hours to days), (3) from multiple areas of interest, (4) in parallel under several different experimental conditions. Quantitation of true individual and average cell velocity and path length was obtained with high spatial and temporal resolution in "scratch" or "wound healing" assays. This revealed unique motility dynamics of drug-treated and adhesion molecule-transfected cells and, thus, this is a considerable improvement over current methods of measurement and analysis. Several fluorescent vital labeling methods commonly used for end-point analyses (GFP expression, DiO lipophilic dye, and Qtracker nanocrystals) were found to be useful for time-lapse studies under specific conditions that are described. To illustrate one application, fluorescently labeled tumor cells were seeded onto cell monolayers expressing ectopic adhesion molecules, and this resulted in consistently reduced tumor cell migration velocities. These highly quantitative time-lapse analysis methods will promote the creation of new cell motility assays and increase the resolution and accuracy of existing assays. PMID:19002890

  13. Flood and Landslide Applications of High Time Resolution Satellite Rain Products

    NASA Technical Reports Server (NTRS)

    Adler, Robert F.; Hong, Yang; Huffman, George J.

    2006-01-01

    Experimental, potentially real-time systems to detect floods and landslides related to heavy rain events are described. A key basis for these applications is high time resolution satellite rainfall analyses. Rainfall is the primary cause for devastating floods across the world. However, in many countries, satellite-based precipitation estimation may be the best source of rainfall data due to insufficient ground networks and absence of data sharing along many trans-boundary river basins. Remotely sensed precipitation from the NASA's TRMM Multi-satellite Precipitation Analysis (TMPA) operational system (near real-time precipitation at a spatial-temporal resolution of 3 hours and 0.25deg x 0.25deg) is used to monitor extreme precipitation events. Then these data are ingested into a macro-scale hydrological model which is parameterized using spatially distributed elevation, soil and land cover datasets available globally from satellite remote sensing. Preliminary flood results appear reasonable in terms of location and frequency of events, with implementation on a quasi-global basis underway. With the availability of satellite rainfall analyses at fine time resolution, it has also become possible to assess landslide risk on a near-global basis. Early results show that landslide occurrence is closely associated with the spatial patterns and temporal distribution of TRMM rainfall characteristics. Particularly, the number of landslides triggered by rainfall is related to rainfall climatology, antecedent rainfall accumulation, and intensity-duration of rainstorms. For the purpose of prediction, an empirical TMPA-based rainfall intensity-duration threshold is developed and shown to have skill in determining potential areas of landslides. These experimental findings, in combination with landslide surface susceptibility information based on satellite-based land surface information, form a starting point towards a potential operational landslide monitoring/warning system

  14. Time resolution dependence of information measures for spiking neurons: scaling and universality

    PubMed Central

    Marzen, Sarah E.; DeWeese, Michael R.; Crutchfield, James P.

    2015-01-01

    The mutual information between stimulus and spike-train response is commonly used to monitor neural coding efficiency, but neuronal computation broadly conceived requires more refined and targeted information measures of input-output joint processes. A first step toward that larger goal is to develop information measures for individual output processes, including information generation (entropy rate), stored information (statistical complexity), predictable information (excess entropy), and active information accumulation (bound information rate). We calculate these for spike trains generated by a variety of noise-driven integrate-and-fire neurons as a function of time resolution and for alternating renewal processes. We show that their time-resolution dependence reveals coarse-grained structural properties of interspike interval statistics; e.g., τ-entropy rates that diverge less quickly than the firing rate indicated by interspike interval correlations. We also find evidence that the excess entropy and regularized statistical complexity of different types of integrate-and-fire neurons are universal in the continuous-time limit in the sense that they do not depend on mechanism details. This suggests a surprising simplicity in the spike trains generated by these model neurons. Interestingly, neurons with gamma-distributed ISIs and neurons whose spike trains are alternating renewal processes do not fall into the same universality class. These results lead to two conclusions. First, the dependence of information measures on time resolution reveals mechanistic details about spike train generation. Second, information measures can be used as model selection tools for analyzing spike train processes. PMID:26379538

  15. Time resolution dependence of information measures for spiking neurons: scaling and universality.

    PubMed

    Marzen, Sarah E; DeWeese, Michael R; Crutchfield, James P

    2015-01-01

    The mutual information between stimulus and spike-train response is commonly used to monitor neural coding efficiency, but neuronal computation broadly conceived requires more refined and targeted information measures of input-output joint processes. A first step toward that larger goal is to develop information measures for individual output processes, including information generation (entropy rate), stored information (statistical complexity), predictable information (excess entropy), and active information accumulation (bound information rate). We calculate these for spike trains generated by a variety of noise-driven integrate-and-fire neurons as a function of time resolution and for alternating renewal processes. We show that their time-resolution dependence reveals coarse-grained structural properties of interspike interval statistics; e.g., τ-entropy rates that diverge less quickly than the firing rate indicated by interspike interval correlations. We also find evidence that the excess entropy and regularized statistical complexity of different types of integrate-and-fire neurons are universal in the continuous-time limit in the sense that they do not depend on mechanism details. This suggests a surprising simplicity in the spike trains generated by these model neurons. Interestingly, neurons with gamma-distributed ISIs and neurons whose spike trains are alternating renewal processes do not fall into the same universality class. These results lead to two conclusions. First, the dependence of information measures on time resolution reveals mechanistic details about spike train generation. Second, information measures can be used as model selection tools for analyzing spike train processes. PMID:26379538

  16. Time resolution deterioration with increasing crystal length in a TOF-PET system

    NASA Astrophysics Data System (ADS)

    Gundacker, S.; Knapitsch, A.; Auffray, E.; Jarron, P.; Meyer, T.; Lecoq, P.

    2014-02-01

    Highest time resolution in scintillator based detectors is becoming more and more important. In medical detector physics L(Y)SO scintillators are commonly used for time of flight positron emission tomography (TOF-PET). Coincidence time resolutions (CTRs) smaller than 100 ps FWHM are desirable in order to improve the image signal to noise ratio and thus give benefit to the patient by shorter scanning times. Also in high energy physics there is the demand to improve the timing capabilities of calorimeters down to 10 ps. To achieve these goals it is important to study the whole chain, i.e. the high energy particle interaction in the crystal, the scintillation process itself, the scintillation light transfer in the crystal, the photodetector and the electronics. Time resolution measurements for a PET like system are performed with the time-over-threshold method in a coincidence setup utilizing the ultra-fast amplifier-discriminator NINO. With 2×2×3 mm3 LSO:Ce codoped 0.4%Ca crystals coupled to commercially available SiPMs (Hamamatsu S10931-050P MPPC) we achieve a CTR of 108±5 ps FWHM at an energy of 511 keV. Under the same experimental conditions an increase in crystal length to 5 mm deteriorates the CTR to 123±7 ps FWHM, 10 mm to 143±7 ps FWHM and 20 mm to 176±7 ps FWHM. This degradation in CTR is caused by the light transfer efficiency (LTE) and light transfer time spread (LTTS) in the crystal. To quantitatively understand the measured values, we developed a Monte Carlo simulation tool in MATLAB incorporating the timing properties of the photodetector and electronics, the scintillation properties of the crystal and the light transfer within the crystal simulated by SLITRANI. In this work, we show that the predictions of the simulation are in good agreement with the experimental data. We conclude that for longer crystals the deterioration in CTR is mainly caused by the LTE, i.e. the ratio of photons reaching the photodetector to the total amount of photons

  17. Accurate estimation of the RMS emittance from single current amplifier data

    SciTech Connect

    Stockli, Martin P.; Welton, R.F.; Keller, R.; Letchford, A.P.; Thomae, R.W.; Thomason, J.W.G.

    2002-05-31

    This paper presents the SCUBEEx rms emittance analysis, a self-consistent, unbiased elliptical exclusion method, which combines traditional data-reduction methods with statistical methods to obtain accurate estimates for the rms emittance. Rather than considering individual data, the method tracks the average current density outside a well-selected, variable boundary to separate the measured beam halo from the background. The average outside current density is assumed to be part of a uniform background and not part of the particle beam. Therefore the average outside current is subtracted from the data before evaluating the rms emittance within the boundary. As the boundary area is increased, the average outside current and the inside rms emittance form plateaus when all data containing part of the particle beam are inside the boundary. These plateaus mark the smallest acceptable exclusion boundary and provide unbiased estimates for the average background and the rms emittance. Small, trendless variations within the plateaus allow for determining the uncertainties of the estimates caused by variations of the measured background outside the smallest acceptable exclusion boundary. The robustness of the method is established with complementary variations of the exclusion boundary. This paper presents a detailed comparison between traditional data reduction methods and SCUBEEx by analyzing two complementary sets of emittance data obtained with a Lawrence Berkeley National Laboratory and an ISIS H{sup -} ion source.

  18. Microchannel Plate Imaging Photon Counters for Ultraviolet through NIR Detection with High Time Resolution

    PubMed Central

    Siegmund, Oswald H.W.; Vallerga, John V.; Tremsin, Anton S.; McPhate, Jason; Michalet, X.; Colyer, R. A.; Weiss, S.

    2013-01-01

    Cross strip and cross delay line readout microchannel plate detectors in 18 mm, 25 mm and 40 mm active area formats including open face (UV/particle) and sealed tube (optical) configurations have been constructed. These have been tested with a field programmable gate array based electronics for single event encoding. Using small pore MCPs (6 μm) operated in a pair, we achieve gains of >1 × 106 which is sufficient to provide spatial resolution of ~17 μm FHWM with the 18 mm and 40 mm cross strip readouts. New cross strip electronics can process high output event rates (> 4 MHz) with high spatial resolution, and self triggered event timing accuracy of ~1.5 ns for sealed tube XS optical sensors. A peak quantum efficiency of between 13% and 19% at 500 nm has been achieved with SuperGenII photocathodes with response from 400 nm to 900 nm for both cross strip and cross delay line sealed tubes. Local area counting rates of up to 40 kHz (100μm spot) have been attained with XS sealed tubes, along with image linearity and stability to better than 50 μm. 25mm cross delay line tubes achieve ~50 μm resolution and > 2 MHz output event rates. PMID:23833700

  19. High-resolution time-lapse tomography of rat vertebrae during compressive loading: deformation response analysis

    NASA Astrophysics Data System (ADS)

    Fíla, T.; Kytýř, D.; Zlámal, P.; Kumpová, I.; Doktor, T.; Koudelka, P.; Jiroušek, O.

    2014-05-01

    This paper is focused on investigation of mechanical properties of rat vertebrae during compressive loading in the longitudinal direction of rat's spine. High-resolution time-lapse micro-tomography was used as a tool to create models of the inner structure and deformed shape in pre-defined deformation steps. First, peripheral areas of vertebra specimen were embedded in polymethyl methacrylate to obtain proper boundary conditions of contact between specimen and loading plattens. Experimental loading device designed for application in X-ray setups was utilized to compress the vertebrae in several deformation steps. High-resolution micro-tomography scanning was carried out at each deformation step. Specimen was irradiated in tomography device equipped with microfocus X-ray tube with 5μm focal spot size and large area flat panel detector. Spatial resolution of reconstructed three-dimensional images was approximately 10μm. Digital volume correlation algorithm was utilized in order to assess displacements in the microstructure in every loading increment. Finite element model of vertebra was created from volumetric data reconstructed from tomography of the undeformed specimen. Simulated compressive test of the developed finite element model was performed in order to compare stiffness and displacements obtained by digital volume correlation and finite element simulation.

  20. Gamma ray spectroscopy at high energy and high time resolution at JET.

    PubMed

    Tardocchi, M; Proverbio, L I; Gorini, G; Grosso, G; Locatelli, M; Chugonov, I N; Gin, D B; Shevelev, A E; Murari, A; Kiptily, V G; Syme, B; Fernandes, A M; Pereira, R C; Sousa, J

    2008-10-01

    In fusion plasmas gamma ray emission is caused by reactions of fast particles, such as fusion alpha particles, with impurities. Gamma ray spectroscopy at JET has provided valuable diagnostic information on fast fuel as well as fusion product ions. Improvements of these measurements are needed to fully exploit the flux increase provided by future high power experiments at JET and ITER. Limiting aspects are, for instance, the count rate capability due to a high neutron/gamma background combined with slow detector response and a modest energy resolution due to the low light yield of the scintillators. This paper describes the solutions developed for achieving higher energy resolution, signal to background, and time resolution. The detector design is described based on the new BrLa3 scintillator crystal. The paper will focus on hardware development, including a photomultiplier tube capable of stable operation at counting rate as high as 1 MHz, the magnetic shielding, and the fast digital data acquisition system. PMID:19068513

  1. Rms-flux relation and fast optical variability simulations of the nova-like system MV Lyr

    NASA Astrophysics Data System (ADS)

    Dobrotka, A.; Mineshige, S.; Ness, J.-U.

    2015-03-01

    The stochastic variability (flickering) of the nova-like system (subclass of cataclysmic variable) MV Lyr yields a complicated power density spectrum with four break frequencies. Scaringi et al. analysed high-cadence Kepler data of MV Lyr, taken almost continuously over 600 d, giving the unique opportunity to study multicomponent Power Density Spectra (PDS) over a wide frequency range. We modelled this variability with our statistical model based on disc angular momentum transport via discrete turbulent bodies with an exponential distribution of the dimension scale. Two different models were used, a full disc (developed from the white dwarf to the outer radius of ˜1010 cm) and a radially thin disc (a ring at a distance of ˜1010 cm from the white dwarf) that imitates an outer disc rim. We succeed in explaining the two lowest observed break frequencies assuming typical values for a disc radius of 0.5 and 0.9 times the primary Roche lobe and an α parameter of 0.1-0.4. The highest observed break frequency was also modelled, but with a rather small accretion disc with a radius of 0.3 times the primary Roche lobe and a high α value of 0.9 consistent with previous findings by Scaringi. Furthermore, the simulated light curves exhibit the typical linear rms-flux proportionality linear relation and the typical log-normal flux distribution. As the turbulent process is generating fluctuations in mass accretion that propagate through the disc, this confirms the general knowledge that the typical rms-flux relation is mainly generated by these fluctuations. In general, a higher rms is generated by a larger amount of superposed flares which is compatible with a higher mass accretion rate expressed by a larger flux.

  2. High-Resolution Time-Lapse Monitoring of Unsaturated Flow using Automated GPR Data Collection

    NASA Astrophysics Data System (ADS)

    Mangel, A. R.; Moysey, S. M.; Lytle, B. A.; Bradford, J. H.

    2015-12-01

    High-resolution ground-penetrating radar (GPR) data provide the detailed information required to image subsurface structures. Recent advances in GPR monitoring now also make it possible to study transient hydrologic processes, but high-speed data acquisition is critical for this application. We therefore highlight the capabilities of our automated system to acquire time-lapse, high-resolution multifold GPR data during infiltration of water into soils. The system design allows for fast acquisition of constant-offset (COP) and common-midpoint profiles (CMP) to monitor unsaturated flow at multiple locations. Qualitative interpretation of the unprocessed COPs can provide substantial information regarding the hydrologic response of the system, such as the complexities of patterns associated with the wetting of the soil and geophysical evidence of non-uniform propagation of a wetting front. While we find that unprocessed images are informative, we show that the spatial variability of velocity introduced by infiltration events can complicate the images and that migration of the data is an effective tool to improve interpretability of the time-lapse images. The ability of the system to collect high density CMP data also introduces the potential for improving the velocity model along with the image via reflection tomography in the post-migrated domain. We show that for both simulated and empirical time-lapse GPR profiles we can resolve a propagating wetting front in the soil that is in good agreement with the response of in-situ soil moisture measurements. The data from these experiments illustrate the importance of high-speed, high-resolution GPR data acquisition for obtaining insight about the dynamics of hydrologic events. Continuing research is aimed at improving the quantitative analysis of surface-based GPR monitoring data for identifying preferential flow in soils.

  3. Shower disc sampling and the angular resolution of gamma-ray shower detectors

    NASA Technical Reports Server (NTRS)

    Lambert, A.; Lloyd-Evans, J.

    1985-01-01

    As part of the design study for the new UHE gamma ray detector being constsructed at Haverah Park, a series of experiments using scintillators operated side-by-side in 10 to the 15th power eV air showers are undertaken. Investigation of the rms sampling fluctuations in the shower disc arrival time yields an upper limit to the intrinsic sampling uncertainty, sigma sub rms = (1.1 + or - 0.1)ns, implying an angular resolution capability 1 deg for an inter-detector spacing of approximately 25 m.

  4. Electron-optical metrology with femtosecond time resolution (theory and experiment)

    SciTech Connect

    Andreev, S V; Vorob'ev, Nikolai S; Greenfield, D E; Lozovoi, V I; Monastyrskii, M A; Serdyuchenko, Yu N; Smirnov, A V; Shchelev, Mikhail Ya

    2013-04-30

    The principles of simultaneous spatial and temporal focusing of photoelectron beams in nonstationary electric fields are theoretically studied and experimentally realised as applied to time-analysing image-converter tubes (ICTs). It is theoretically shown that the use of nonstationary focusing electric fields makes it possible to surpass the theoretical time resolution limit of ICTs (10{sup -4} s) determined for stationary fields by Zavoisky and Fanchenko in the 40s-50s of the last century. The possibility of forming electron packets with an energy of 10-30 KeV and a subfemtosecond duration (below 10{sup -15} s) gives impetus to the development of time-resolved electron diffraction, which is a direct method of investigation of atomic-molecular dynamics in solid and gaseous media. (extreme light fields and their applications)

  5. ns-time resolution for multispecies STED-FLIM and artifact free STED-FCS

    NASA Astrophysics Data System (ADS)

    Koenig, Marcelle; Reisch, Paja; Dowler, Rhys; Kraemer, Benedikt; Tannert, Sebastian; Patting, Matthias; Clausen, Mathias P.; Galiani, Silvia; Eggeling, Christian; Koberling, Felix; Erdmann, Rainer

    2016-03-01

    Stimulated Emission Depletion (STED) Microscopy has evolved into a well established method offering optical superresolution below 50 nm. Running both excitation and depletion lasers in picosecond pulsed modes allows for highest optical resolution as well as fully exploiting the photon arrival time information using time-resolved single photon counting (TCSPC). Non-superresolved contributions can be easily dismissed through time-gated detection (gated STED) or a more detailed fluorescence decay analysis (FLIM-STED), both leading to an even further improved imaging resolution. Furthermore, these methods allow for accurate separation of different fluorescent species, especially if subtle differences in the excitation and emission spectra as well as the fluorescence decay are taken into account in parallel. STED can also be used to shrink the observation volume while studying the dynamics of diffusing species in Fluorescence Correlation Spectroscopy (FCS) to overcome averaging issues along long transit paths. A further unique advantage of STED-FCS is that the observation spot diameter can be tuned in a gradual manner enabling, for example, determining the type of hindered diffusion in lipid membrane studies. Our completely pulsed illumination scheme allows realizing an improved STED-FCS data acquisition using pulsed interleaved excitation (PIE). PIE-STED-FCS allows for a straightforward online check whether the STED laser has an influence on the investigated diffusion dynamics.

  6. New ultrarapid-scanning interferometer for FT-IR spectroscopy with microsecond time-resolution.

    PubMed

    Süss, B; Ringleb, F; Heberle, J

    2016-06-01

    A novel Fourier-transform infrared (FT-IR) rapid-scan spectrometer has been developed (patent pending EP14194520.4) which yields 1000 times higher time resolution as compared to conventional rapid-scanning spectrometers. The central element to achieve faster scanning rates is based on a sonotrode whose front face represents the movable mirror of the interferometer. A prototype spectrometer with a time resolution of 13 μs was realized, capable of fully automated long-term measurements with a flow cell for liquid samples, here a photosynthetic membrane protein in solution. The performance of this novel spectrometer is demonstrated by recording the photoreaction of bacteriorhodopsin initiated by a short laser pulse that is synchronized to the data recording. The resulting data are critically compared to those obtained by step-scan spectroscopy and demonstrate the relevance of performing experiments on proteins in solution. The spectrometer allows for future investigations of fast, non-repetitive processes, whose investigation is challenging to step-scan FT-IR spectroscopy. PMID:27370432

  7. Optimal Short-Time Acquisition Schemes in High Angular Resolution Diffusion-Weighted Imaging

    PubMed Central

    Prčkovska, V.; Achterberg, H. C.; Bastiani, M.; Pullens, P.; Balmashnova, E.; ter Haar Romeny, B. M.; Vilanova, A.; Roebroeck, A.

    2013-01-01

    This work investigates the possibilities of applying high-angular-resolution-diffusion-imaging- (HARDI-) based methods in a clinical setting by investigating the performance of non-Gaussian diffusion probability density function (PDF) estimation for a range of b-values and diffusion gradient direction tables. It does so at realistic SNR levels achievable in limited time on a high-performance 3T system for the whole human brain in vivo. We use both computational simulations and in vivo brain scans to quantify the angular resolution of two selected reconstruction methods: Q-ball imaging and the diffusion orientation transform. We propose a new analytical solution to the ODF derived from the DOT. Both techniques are analytical decomposition approaches that require identical acquisition and modest postprocessing times and, given the proposed modifications of the DOT, can be analyzed in a similar fashion. We find that an optimal HARDI protocol given a stringent time constraint (<10 min) combines a moderate b-value (around 2000 s/mm2) with a relatively low number of acquired directions (>48). Our findings generalize to other methods and additional improvements in MR acquisition techniques. PMID:23554808

  8. Real-time haptic cutting of high-resolution soft tissues.

    PubMed

    Wu, Jun; Westermann, Rüdiger; Dick, Christian

    2014-01-01

    We present our systematic efforts in advancing the computational performance of physically accurate soft tissue cutting simulation, which is at the core of surgery simulators in general. We demonstrate a real-time performance of 15 simulation frames per second for haptic soft tissue cutting of a deformable body at an effective resolution of 170,000 finite elements. This is achieved by the following innovative components: (1) a linked octree discretization of the deformable body, which allows for fast and robust topological modifications of the simulation domain, (2) a composite finite element formulation, which thoroughly reduces the number of simulation degrees of freedom and thus enables to carefully balance simulation performance and accuracy, (3) a highly efficient geometric multigrid solver for solving the linear systems of equations arising from implicit time integration, (4) an efficient collision detection algorithm that effectively exploits the composition structure, and (5) a stable haptic rendering algorithm for computing the feedback forces. Considering that our method increases the finite element resolution for physically accurate real-time soft tissue cutting simulation by an order of magnitude, our technique has a high potential to significantly advance the realism of surgery simulators. PMID:24732558

  9. High-resolution imaging characterization of bladder dynamic morphophysiology by time-lapse optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Pan, Y. T.; Wu, Q.; Wang, Z. G.; Brink, P. R.; Du, C. W.

    2005-09-01

    We report an experimental study of the possibility of high-speed optical coherence tomography (OCT) for high-resolution imaging characterization of detrusor dynamic morphophysiology and analysis of the mechanisms that lead to geriatric incontinence (GI). The spontaneous contractility of intact fresh rabbit bladders was imaged with two-dimensional (2D) OCT ex vivo at up to 8frames/s. The time-lapse 2D OCT images were postprocessed by image segmentation and fast-Fourier-transform analysis to characterize the dynamic morphological changes of the bladder contractility. In addition, we studied young and aging rat bladders to analyze the differences in dynamics. Preliminary results of our ex vivo study reveal that time-lapse OCT can track the contractile waves of bladders at high spatial resolution and characterize their dynamic morphophysiology in terms of amplitude, phase, and frequency. The results suggest that time-lapse OCT has the potential to act as a detrusor optical biopsy to enhance the diagnosis of detrusor dysfunction and thus of the mechanisms that lead to GI.

  10. Real-time dictionary based super-resolution of surveillance video streams and targets

    NASA Astrophysics Data System (ADS)

    Hospedales, Timothy M.; Gong, Shaogang

    2012-10-01

    Real-time super-resolution within surveillance video streams is a powerful tool for security and crime prevention allowing for example, events, faces or objects such number-plates and luggage to be more accurately identified on the fly and from a distance. However, many of the state of the art approaches to super-resolution are computationally too expensive to be suitable for real-time applications within a surveillance context. We consider one particular contemporary method based on sparse coding,1 and show how, by relaxing some model constraints, it can be sped up significantly compared to the reference implementation, and thus approach real-time performance with visually indistinct reduction in fidelity. The final computation is three orders of magnitude faster than the reference implementation. The quality of the output is maintained: PSNR of the super-resolved images compared to ground truth is not significantly different to the reference implementation, while maintaining a noticeable improvement over baseline bicubic-interpolation approach.