Science.gov

Sample records for detector dead time

  1. Dead-time effects in microchannel-plate imaging detectors

    NASA Technical Reports Server (NTRS)

    Zombeck, Martin V.; Fraser, George W.

    1991-01-01

    The observed counting rates of microchannel plate (MCP) based detectors for high resolution observations of celestial EUV and X-ray sources vary over many orders of magnitude; the counting capability of an individual channel, however, is not high, and is associated with dead-times ranging from 0.1 msec to 1 sec. The dead-time increases with the area illuminated; attention is presently given to laboratory determinations of the count rate characteristics of a MCP detector as a function of illuminated area, and a model is developed for these results' use in the interpretation of space observations.

  2. Nuclear detector system with reduced dead-time processor circuit

    SciTech Connect

    Schwartz, R.J.

    1987-01-06

    This patent describes for use in a well logging system which has a nuclear event detector forming an output signal of randomly space peaks having amplitudes within a specified range, a reduced dead-time processor circuit which comprises: (a) input means adapted to be connected with a nuclear event detector in a sonde to provide an input signal having arranged for deflecting at least a part of the beam of electrons during passage from a surface of the anode grid structure facing the photocathode to the target.

  3. Dead-time effects in pulse-counting Digicon detectors

    NASA Technical Reports Server (NTRS)

    Ebbets, Dennis C.; Garner, Harry W.

    1986-01-01

    The Hubble Space Telescope's High Resolution Spectrograph employs two pulse-counting Digicon detectors to record UV spectra. At higher measured count rates, the intervals between photon arrivals become comparable to the response time of the electronics, so that not every pulse will be counted; this 'paired pulse' effect causes departures from linearity and must be corrected for during raw data reduction. Attention is given to two analytic equations that quantify the dead-time losses. The less attenuated spectra are noted to be severely distorted by these losses; a comparison with the undistorted low count rate data allows a detailed analysis to be made of the pulse-counting characteristics over five decades of input event rates. The present equations and calibration methods should be applicable to all kinds of multichannel pulse-counting detectors.

  4. Effect of detector dead time on the performance of optical direct-detection communication links

    NASA Technical Reports Server (NTRS)

    Chen, C.-C.

    1988-01-01

    Avalanche photodiodes (APDs) operating in the Geiger mode can provide a significantly improved single-photon detection sensitivity over conventional photodiodes. However, the quenching circuit required to remove the excess charge carriers after each photon event can introduce an undesirable dead time into the detection process. The effect of this detector dead time on the performance of a binary pulse-position-modulated (PPM) channel is studied by analyzing the error probability. It is shown that, when background noise is negligible, the performance of the detector with dead time is similar to that of a quantum-limited receiver. For systems with increasing background intensities, the error rate of the receiver starts to degrade rapidly with increasing dead time. The power penalty due to detector dead time is also evaluated and shown to depend critically on badkground intensity as well as dead time. Given the expected background strength in an optical channel, therefore, a constraint must be placed on the bandwidth of the receiver to limit the amount of power penalty due to detector dead time.

  5. Effect of Detector Dead Time on the Performance of Optical Direct-Detection Communication Links

    NASA Technical Reports Server (NTRS)

    Chen, C.-C.

    1988-01-01

    Avalanche photodiodes (APDs) operating in the Geiger mode can provide a significantly improved single-photon detect ion sensitivity over conventional photodiodes. However, the quenching circuit required to remove the excess charge carriers after each photon event can introduce an undesirable dead time into the detection process. The effect of this detector dead time on the performance of a binary pulse-position-modulted (PPM) channel is studied by analyzing the error probability. It is shown that, when back- ground noise is negligible, the performance of the detector with dead time is similar to that o f a quantum-limited receiver. For systems with increasing background intensities, the error rate of the receiver starts to degrade rapidly with increasing dead time. The power penalty due to detector dead time is also evaluated and shown to depend critically on background intensity as well as dead time. Given the expected background strength in an optical channel, therefore, a constraint must be placed on the bandwidth of the receiver to limit the amount of power penalty due to detector dead time.

  6. Effect of detector dead time on the performance of optical direct-detection communication links

    NASA Astrophysics Data System (ADS)

    Chen, C.-C.

    1988-05-01

    Avalanche photodiodes (APDs) operating in the Geiger mode can provide a significantly improved single-photon detection sensitivity over conventional photodiodes. However, the quenching circuit required to remove the excess charge carriers after each photon event can introduce an undesirable dead time into the detection process. The effect of this detector dead time on the performance of a binary pulse-position-modulated (PPM) channel is studied by analyzing the error probability. It is shown that, when background noise is negligible, the performance of the detector with dead time is similar to that of a quantum-limited receiver. For systems with increasing background intensities, the error rate of the receiver starts to degrade rapidly with increasing dead time. The power penalty due to detector dead time is also evaluated and shown to depend critically on badkground intensity as well as dead time. Given the expected background strength in an optical channel, therefore, a constraint must be placed on the bandwidth of the receiver to limit the amount of power penalty due to detector dead time.

  7. YALINA-booster subcritical assembly pulsed-neutron e xperiments: detector dead time and apatial corrections.

    SciTech Connect

    Cao, Y.; Gohar, Y.; Nuclear Engineering Division

    2010-10-11

    In almost every detector counting system, a minimal dead time is required to record two successive events as two separated pulses. Due to the random nature of neutron interactions in the subcritical assembly, there is always some probability that a true neutron event will not be recorded because it occurs too close to the preceding event. These losses may become rather severe for counting systems with high counting rates, and should be corrected before any utilization of the experimental data. This report examines the dead time effects for the pulsed neutron experiments of the YALINA-Booster subcritical assembly. The nonparalyzable model is utilized to correct the experimental data due to dead time. Overall, the reactivity values are increased by 0.19$ and 0.32$ after the spatial corrections for the YALINA-Booster 36% and 21% configurations respectively. The differences of the reactivities obtained with He-3 long or short detectors at the same detector channel diminish after the dead time corrections of the experimental data for the 36% YALINA-Booster configuration. In addition, better agreements between reactivities obtained from different experimental data sets are also observed after the dead time corrections for the 21% YALINA-Booster configuration.

  8. A 65 nm CMOS analog processor with zero dead time for future pixel detectors

    NASA Astrophysics Data System (ADS)

    Gaioni, L.; Braga, D.; Christian, D. C.; Deptuch, G.; Fahim, F.; Nodari, B.; Ratti, L.; Re, V.; Zimmerman, T.

    2017-02-01

    Next generation pixel chips at the High-Luminosity (HL) LHC will be exposed to extremely high levels of radiation and particle rates. In the so-called Phase II upgrade, ATLAS and CMS will need a completely new tracker detector, complying with the very demanding operating conditions and the delivered luminosity (up to 5×1034 cm-2 s-1 in the next decade). This work is concerned with the design of a synchronous analog processor with zero dead time developed in a 65 nm CMOS technology, conceived for pixel detectors at the HL-LHC experiment upgrades. It includes a low noise, fast charge sensitive amplifier featuring a detector leakage compensation circuit, and a compact, single ended comparator that guarantees very good performance in terms of channel-to-channel dispersion of threshold without needing any pixel-level trimming. A flash ADC is exploited for digital conversion immediately after the charge amplifier. A thorough discussion on the design of the charge amplifier and the comparator is provided along with an exhaustive set of simulation results.

  9. Correction for the detector-dead-time effect on the second-order correlation of stationary sub-Poissonian light in a two-detector configuration

    NASA Astrophysics Data System (ADS)

    Ann, Byoung-moo; Song, Younghoon; Kim, Junki; Yang, Daeho; An, Kyungwon

    2015-08-01

    Exact measurement of the second-order correlation function g(2 )(t ) of a light source is essential when investigating the photon statistics and the light generation process of the source. For a stationary single-mode light source, the Mandel Q factor is directly related to g(2 )(0 ) . For a large mean photon number in the mode, the deviation of g(2 )(0 ) from unity is so small that even a tiny error in measuring g(2 )(0 ) would result in an inaccurate Mandel Q . In this work, we address the detector-dead-time effect on g(2 )(0 ) of stationary sub-Poissonian light. It is then found that detector dead time can induce a serious error in g(2 )(0 ) and thus in Mandel Q in those cases even in a two-detector configuration. Utilizing the cavity-QED microlaser, a well-established sub-Poissonian light source, we measured g(2 )(0 ) with two different types of photodetectors with different dead times. We also introduced prolonged dead time by intentionally deleting the photodetection events following a preceding one within a specified time interval. We found that the observed Q of the cavity-QED microlaser was underestimated by 19% with respect to the dead-time-free Q when its mean photon number was about 600. We derived an analytic formula which well explains the behavior of the g(2 )(0 ) as a function of the dead time.

  10. Correction of dead-time and pile-up in a detector array for constant and rapidly varying counting rates

    NASA Astrophysics Data System (ADS)

    Guerrero, C.; Cano-Ott, D.; Mendoza, E.; Wright, T.

    2015-03-01

    The effect of dead-time and pile-up in counting experiments may become a significant source of uncertainty if not properly taken into account. Although analytical solutions to this problem have been proposed for simple set-ups with one or two detectors, these are limited when it comes to arrays where time correlation between the detector modules is used, and also in situations of variable counting rates. In this paper we describe the dead-time and pile-up corrections applied to the n_TOF Total Absorption Calorimeter (TAC), a 4π γ-ray detector made of 40 BaF2 modules operating at the CERN n_TOF facility. Our method is based on the simulation of the complete signal detection and event reconstruction processes and can be applied as well in the case of rapidly varying counting rates. The method is discussed in detail and then we present its successful application to the particular case of the measurement of 238U(n, γ) reactions with the TAC detector.

  11. Measurement of the front-end dead-time of the LHCb muon detector and evaluation of its contribution to the muon detection inefficiency

    NASA Astrophysics Data System (ADS)

    Anderlini, L.; Anelli, M.; Archilli, F.; Auriemma, G.; Baldini, W.; Bencivenni, G.; Bizzeti, A.; Bocci, V.; Bondar, N.; Bonivento, W.; Bochin, B.; Bozzi, C.; Brundu, D.; Cadeddu, S.; Campana, P.; Carboni, G.; Cardini, A.; Carletti, M.; Casu, L.; Chubykin, A.; Ciambrone, P.; Dané, E.; De Simone, P.; Falabella, A.; Felici, G.; Fiore, M.; Fontana, M.; Fresch, P.; Furfaro, E.; Graziani, G.; Kashchuk, A.; Kotriakhova, S.; Lai, A.; Lanfranchi, G.; Loi, A.; Maev, O.; Manca, G.; Martellotti, G.; Neustroev, P.; Oldeman, R. G. C.; Palutan, M.; Passaleva, G.; Penso, G.; Pinci, D.; Polycarpo, E.; Saitta, B.; Santacesaria, R.; Santimaria, M.; Santovetti, E.; Saputi, A.; Sarti, A.; Satriano, C.; Satta, A.; Schmidt, B.; Schneider, T.; Sciascia, B.; Sciubba, A.; Siddi, B. G.; Tellarini, G.; Vacca, C.; Vazquez-Gomez, R.; Vecchi, S.; Veltri, M.; Vorobyev, A.

    2016-04-01

    A method is described which allows to deduce the dead-time of the front-end electronics of the LHCb muon detector from a series of measurements performed at different luminosities at a bunch-crossing rate of 20 MHz. The measured values of the dead-time range from ~ 70 ns to ~ 100 ns. These results allow to estimate the performance of the muon detector at the future bunch-crossing rate of 40 MHz and at higher luminosity.

  12. Success and failure of dead-time models as applied to hybrid pixel detectors in high-flux applications

    PubMed Central

    Sobott, B. A.; Broennimann, Ch.; Schmitt, B.; Trueb, P.; Schneebeli, M.; Lee, V.; Peake, D. J.; Elbracht-Leong, S.; Schubert, A.; Kirby, N.; Boland, M. J.; Chantler, C. T.; Barnea, Z.; Rassool, R. P.

    2013-01-01

    The performance of a single-photon-counting hybrid pixel detector has been investigated at the Australian Synchrotron. Results are compared with the body of accepted analytical models previously validated with other detectors. Detector functionals are valuable for empirical calibration. It is shown that the matching of the detector dead-time with the temporal synchrotron source structure leads to substantial improvements in count rate and linearity of response. Standard implementations are linear up to ∼0.36 MHz pixel−1; the optimized linearity in this configuration has an extended range up to ∼0.71 MHz pixel−1; these are further correctable with a transfer function to ∼1.77 MHz pixel−1. This new approach has wide application both in high-accuracy fundamental experiments and in standard crystallographic X-ray fluorescence and other X-ray measurements. The explicit use of data variance (rather than N 1/2 noise) and direct measures of goodness-of-fit (χr 2) are introduced, raising issues not encountered in previous literature for any detector, and suggesting that these inadequacies of models may apply to most detector types. Specifically, parametrization of models with non-physical values can lead to remarkable agreement for a range of count-rate, pulse-frequency and temporal structure. However, especially when the dead-time is near resonant with the temporal structure, limitations of these classical models become apparent. Further, a lack of agreement at extreme count rates was evident. PMID:23412493

  13. Success and failure of dead-time models as applied to hybrid pixel detectors in high-flux applications.

    PubMed

    Sobott, B A; Broennimann, Ch; Schmitt, B; Trueb, P; Schneebeli, M; Lee, V; Peake, D J; Elbracht-Leong, S; Schubert, A; Kirby, N; Boland, M J; Chantler, C T; Barnea, Z; Rassool, R P

    2013-03-01

    The performance of a single-photon-counting hybrid pixel detector has been investigated at the Australian Synchrotron. Results are compared with the body of accepted analytical models previously validated with other detectors. Detector functionals are valuable for empirical calibration. It is shown that the matching of the detector dead-time with the temporal synchrotron source structure leads to substantial improvements in count rate and linearity of response. Standard implementations are linear up to ∼0.36 MHz pixel(-1); the optimized linearity in this configuration has an extended range up to ∼0.71 MHz pixel(-1); these are further correctable with a transfer function to ∼1.77 MHz pixel(-1). This new approach has wide application both in high-accuracy fundamental experiments and in standard crystallographic X-ray fluorescence and other X-ray measurements. The explicit use of data variance (rather than N(1/2) noise) and direct measures of goodness-of-fit (χ(r)(2)) are introduced, raising issues not encountered in previous literature for any detector, and suggesting that these inadequacies of models may apply to most detector types. Specifically, parametrization of models with non-physical values can lead to remarkable agreement for a range of count-rate, pulse-frequency and temporal structure. However, especially when the dead-time is near resonant with the temporal structure, limitations of these classical models become apparent. Further, a lack of agreement at extreme count rates was evident.

  14. Conceptual design of the TRACE detector readout using a compact, dead time-less analog memory ASIC

    NASA Astrophysics Data System (ADS)

    Aliaga, R. J.; Herrero-Bosch, V.; Capra, S.; Pullia, A.; Dueñas, J. A.; Grassi, L.; Triossi, A.; Domingo-Pardo, C.; Gadea, R.; González, V.; Hüyük, T.; Sanchís, E.; Gadea, A.; Mengoni, D.

    2015-11-01

    The new TRacking Array for light Charged particle Ejectiles (TRACE) detector system requires monitorization and sampling of all pulses in a large number of channels with very strict space and power consumption restrictions for the front-end electronics and cabling. Its readout system is to be based on analog memory ASICs with 64 channels each that sample a 1 μs window of the waveform of any valid pulses at 200 MHz while discarding any other signals and are read out at 50 MHz with external ADC digitization. For this purpose, a new, compact analog memory architecture is described that allows pulse capture with zero dead time in any channel while vastly reducing the total number of storage cells, particularly for large amounts of input channels. This is accomplished by partitioning the typical Switched Capacitor Array structure into two pipelined, asymmetric stages and introducing FIFO queue-like control circuitry for captured data, achieving total independence between the capture and readout operations.

  15. A zero dead-time multi-particle time and position sensitive detector based on correlation between brightness and amplitude

    NASA Astrophysics Data System (ADS)

    Urbain, X.; Bech, D.; Van Roy, J.-P.; Géléoc, M.; Weber, S. J.; Huetz, A.; Picard, Y. J.

    2015-02-01

    A new multi-particle time and position sensitive detector using only a set of microchannel plates, a waveform digitizer, a phosphor screen, and a CMOS camera is described. The assignment of the timing information, as taken from the microchannel plates by fast digitizing, to the positions, as recorded by the camera, is based on the COrrelation between the BRightness of the phosphor screen spots, defined as their integrated intensity and the Amplitude of the electrical signals (COBRA). Tests performed by observing the dissociation of HeH, the fragmentation of H3 into two or three fragments, and the photo-double-ionization of Xenon atoms are presented, which illustrate the performances of the COBRA detection scheme.

  16. A zero dead-time multi-particle time and position sensitive detector based on correlation between brightness and amplitude.

    PubMed

    Urbain, X; Bech, D; Van Roy, J-P; Géléoc, M; Weber, S J; Huetz, A; Picard, Y J

    2015-02-01

    A new multi-particle time and position sensitive detector using only a set of microchannel plates, a waveform digitizer, a phosphor screen, and a CMOS camera is described. The assignment of the timing information, as taken from the microchannel plates by fast digitizing, to the positions, as recorded by the camera, is based on the COrrelation between the BRightness of the phosphor screen spots, defined as their integrated intensity and the Amplitude of the electrical signals (COBRA). Tests performed by observing the dissociation of HeH, the fragmentation of H3 into two or three fragments, and the photo-double-ionization of Xenon atoms are presented, which illustrate the performances of the COBRA detection scheme.

  17. A zero dead-time multi-particle time and position sensitive detector based on correlation between brightness and amplitude

    SciTech Connect

    Urbain, X. Bech, D.; Van Roy, J.-P.; Géléoc, M.; Weber, S. J.

    2015-02-15

    A new multi-particle time and position sensitive detector using only a set of microchannel plates, a waveform digitizer, a phosphor screen, and a CMOS camera is described. The assignment of the timing information, as taken from the microchannel plates by fast digitizing, to the positions, as recorded by the camera, is based on the COrrelation between the BRightness of the phosphor screen spots, defined as their integrated intensity and the Amplitude of the electrical signals (COBRA). Tests performed by observing the dissociation of HeH, the fragmentation of H{sub 3} into two or three fragments, and the photo-double-ionization of Xenon atoms are presented, which illustrate the performances of the COBRA detection scheme.

  18. Submillisecond X-ray photon correlation spectroscopy from a pixel array detector with fast dual gating and no readout dead-time

    DOE PAGES

    Zhang, Qingteng; Dufresne, Eric M.; Grybos, Pawel; ...

    2016-01-01

    Small-angle scattering X-ray photon correlation spectroscopy (XPCS) studies were performed using a novel photon-counting pixel array detector with dual counters for each pixel. Each counter can be read out independently from the other to ensure there is no readout dead-time between the neighboring frames. A maximum frame rate of 11.8 kHz was achieved. Results on test samples show good agreement with simple diffusion. As a result, the potential of extending the time resolution of XPCS beyond the limit set by the detector frame rate using dual counters is also discussed.

  19. Submillisecond X-ray photon correlation spectroscopy from a pixel array detector with fast dual gating and no readout dead-time

    PubMed Central

    Zhang, Qingteng; Dufresne, Eric M.; Grybos, Pawel; Kmon, Piotr; Maj, Piotr; Narayanan, Suresh; Deptuch, Grzegorz W.; Szczygiel, Robert; Sandy, Alec

    2016-01-01

    Small-angle scattering X-ray photon correlation spectroscopy (XPCS) studies were performed using a novel photon-counting pixel array detector with dual counters for each pixel. Each counter can be read out independently from the other to ensure there is no readout dead-time between the neighboring frames. A maximum frame rate of 11.8 kHz was achieved. Results on test samples show good agreement with simple diffusion. The potential of extending the time resolution of XPCS beyond the limit set by the detector frame rate using dual counters is also discussed. PMID:27140146

  20. Submillisecond X-ray photon correlation spectroscopy from a pixel array detector with fast dual gating and no readout dead-time.

    PubMed

    Zhang, Qingteng; Dufresne, Eric M; Grybos, Pawel; Kmon, Piotr; Maj, Piotr; Narayanan, Suresh; Deptuch, Grzegorz W; Szczygiel, Robert; Sandy, Alec

    2016-05-01

    Small-angle scattering X-ray photon correlation spectroscopy (XPCS) studies were performed using a novel photon-counting pixel array detector with dual counters for each pixel. Each counter can be read out independently from the other to ensure there is no readout dead-time between the neighboring frames. A maximum frame rate of 11.8 kHz was achieved. Results on test samples show good agreement with simple diffusion. The potential of extending the time resolution of XPCS beyond the limit set by the detector frame rate using dual counters is also discussed.

  1. Submillisecond X-ray photon correlation spectroscopy from a pixel array detector with fast dual gating and no readout dead-time

    SciTech Connect

    Zhang, Qingteng; Dufresne, Eric M.; Grybos, Pawel; Kmon, Piotr; Maj, Piotr; Narayanan, Suresh; Deptuch, Grzegorz W.; Szczygiel, Robert; Sandy, Alec

    2016-01-01

    Small-angle scattering X-ray photon correlation spectroscopy (XPCS) studies were performed using a novel photon-counting pixel array detector with dual counters for each pixel. Each counter can be read out independently from the other to ensure there is no readout dead-time between the neighboring frames. A maximum frame rate of 11.8 kHz was achieved. Results on test samples show good agreement with simple diffusion. As a result, the potential of extending the time resolution of XPCS beyond the limit set by the detector frame rate using dual counters is also discussed.

  2. Submillisecond X-ray photon correlation spectroscopy from a pixel array detector with fast dual gating and no readout dead-time

    DOE PAGES

    Zhang, Qingteng; Dufresne, Eric M.; Grybos, Pawel; ...

    2016-04-19

    Small-angle scattering X-ray photon correlation spectroscopy (XPCS) studies were performed using a novel photon-counting pixel array detector with dual counters for each pixel. Each counter can be read out independently from the other to ensure there is no readout dead-time between the neighboring frames. A maximum frame rate of 11.8 kHz was achieved. Results on test samples show good agreement with simple diffusion. Lastly, the potential of extending the time resolution of XPCS beyond the limit set by the detector frame rate using dual counters is also discussed.

  3. Submillisecond X-ray photon correlation spectroscopy from a pixel array detector with fast dual gating and no readout dead-time

    SciTech Connect

    Zhang, Qingteng; Dufresne, Eric M.; Grybos, Pawel; Kmon, Piotr; Maj, Piotr; Narayanan, Suresh; Deptuch, Grzegorz W.; Szczygiel, Robert; Sandy, Alec

    2016-04-19

    Small-angle scattering X-ray photon correlation spectroscopy (XPCS) studies were performed using a novel photon-counting pixel array detector with dual counters for each pixel. Each counter can be read out independently from the other to ensure there is no readout dead-time between the neighboring frames. A maximum frame rate of 11.8 kHz was achieved. Results on test samples show good agreement with simple diffusion. Lastly, the potential of extending the time resolution of XPCS beyond the limit set by the detector frame rate using dual counters is also discussed.

  4. Effects of detector dead-time on quantitative analyses involving boron and multi-hit detection events in atom probe tomography.

    PubMed

    Meisenkothen, Frederick; Steel, Eric B; Prosa, Ty J; Henry, Karen T; Prakash Kolli, R

    2015-12-01

    In atom probe tomography (APT), some elements tend to field evaporate preferentially in multi-hit detection events. Boron (B) is one such element. It is thought that a large fraction of the B signal may be lost during data acquisition and is not reported in the mass spectrum or in the 3-D APT reconstruction. Understanding the relationship between the field evaporation behavior of B and the limitations for detecting multi-hit events can provide insight into the signal loss mechanism for B and may suggest ways to improve B detection accuracy. The present work reports data for nominally pure B and for B-implanted silicon (Si) (NIST-SRM2137) at dose levels two-orders of magnitude lower than previously studied by Da Costa, et al. in 2012. Boron concentration profiles collected from SRM2137 specimens qualitatively confirmed a signal loss mechanism is at work in laser pulsed atom probe measurements of B in Si. Ion correlation analysis was used to graphically demonstrate that the detector dead-time results in few same isotope, same charge-state (SISCS) ion pairs being properly recorded in the multi-hit data, explaining why B is consistently under-represented in quantitative analyses. Given the important role of detector dead-time as a signal loss mechanism, the results from three different methods of estimating the detector dead-time are presented. The findings of this study apply to all quantitative analyses that involve multi-hit data, but the dead-time will have the greatest effect on the elements that have a significant quantity of ions detected in multi-hit events. Published by Elsevier B.V.

  5. Empirical dead-time corrections for synchrotron sources.

    PubMed

    Walko, D A; Arms, D A; Landahl, E C

    2008-11-01

    An experimental comparison of models for performing dead-time corrections of photon-counting detectors at synchrotron sources is presented. The performance of several detectors in the three operating modes of the Advanced Photon Source is systematically compared, with particular emphasis on asymmetric fill patterns. Several simple and well known correction formulas are evaluated. The results demonstrate the critical importance of detector speed and synchrotron fill pattern in selecting the proper dead-time correction.

  6. Dead time corrections using the backward extrapolation method

    NASA Astrophysics Data System (ADS)

    Gilad, E.; Dubi, C.; Geslot, B.; Blaise, P.; Kolin, A.

    2017-05-01

    Dead time losses in neutron detection, caused by both the detector and the electronics dead time, is a highly nonlinear effect, known to create high biasing in physical experiments as the power grows over a certain threshold, up to total saturation of the detector system. Analytic modeling of the dead time losses is a highly complicated task due to the different nature of the dead time in the different components of the monitoring system (e.g., paralyzing vs. non paralyzing), and the stochastic nature of the fission chains. In the present study, a new technique is introduced for dead time corrections on the sampled Count Per Second (CPS), based on backward extrapolation of the losses, created by increasingly growing artificially imposed dead time on the data, back to zero. The method has been implemented on actual neutron noise measurements carried out in the MINERVE zero power reactor, demonstrating high accuracy (of 1-2%) in restoring the corrected count rate.

  7. Dead-Time Modifications to Fast Fourier Transform Power Spectra

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Jahoda, K.; Swank, J. H.; Morgan, E. H.; Giles, A. B.

    1995-08-01

    Time series analysis in X-ray astronomy is complicated by the effects of detector dead time which can cause significant departures of power spectra from those expected from simple Poisson statistics. In this paper we study the effects of both the paralyzable and nonparalyzable dead times on the underlying time series which obeys Poisson counting statistics. We present analytical formulae for the autocorrelation function, auto-covariances, and power spectra, for both kinds of dead time. These formulae, taken as a whole, offer a general qualitative and quantitative framework to further understand the effects of dead time in an X-ray detection and data processing system.

  8. Effects of dead time on quantitative dual-energy imaging using a position-sensitive spectroscopic detector

    NASA Astrophysics Data System (ADS)

    Dummott, Louise M.; Schettino, Giuseppe; Seller, Paul; Wilson, Matthew D.; Veale, Matthew C.; Pani, Silvia

    2017-03-01

    Dual energy imaging (DE) is a potential alternative to conventional mammography for patients with dense breasts. It requires intravenous injection of contrast agent (CA) and subsequent acquisition of images at two different energies. Each pixel is seen as a vector and is projected onto a two-material basis, e.g. water, CA, to form separate water-equivalent and CA-equivalent images. On conventional detectors, this requires two separate exposures. Spectroscopic detectors allow multiple images from a single exposure by integrating appropriate energy bands. This work investigates the effects of high count rates on quantitative DE imaging using a CdTe spectroscopic detector. Because of its small pixel size (250 μm), a limitation of the detector is charge sharing between pixels, which must be corrected to avoid degradation of the detected spectrum. However, as charge sharing is identified by neighbouring pixels registering a count in a given readout frame, an effective maximum count rate (EMR) is imposed, above which linearity between incident and detected counts is lost. A simulation was used to model detector response of a test object composed of water and iodine, with different EMRs and incident count rates. Using a known iodine thickness of 0.03 cm, and an EMR of 103 s-1 , the reconstructed thickness of iodine was found to be 97%, 74% and 24% of the true value for incident count rates of 100, 1000 and 10000 photons/pixel/s respectively. The simulation was validated by imaging a water-equivalent test phantom containing iodinated CA at different X-ray currents, to determine the optimum beam conditions.

  9. Dead-time compensation for a logarithmic display rate meter

    DOEpatents

    Larson, John A.; Krueger, Frederick P.

    1988-09-20

    An improved circuit is provided for application to a radiation survey meter that uses a detector that is subject to dead time. The circuit compensates for dead time over a wide range of count rates by producing a dead-time pulse for each detected event, a live-time pulse that spans the interval between dead-time pulses, and circuits that average the value of these pulses over time. The logarithm of each of these values is obtained and the logarithms are subtracted to provide a signal that is proportional to a count rate that is corrected for the effects of dead time. The circuit produces a meter indication and is also capable of producing an audible indication of detected events.

  10. Dead-time compensation for a logarithmic display rate meter

    DOEpatents

    Larson, J.A.; Krueger, F.P.

    1987-10-05

    An improved circuit is provided for application to a radiation survey meter that uses a detector that is subject to dead time. The circuit compensates for dead time over a wide range of count rates by producing a dead-time pulse for each detected event, a live-time pulse that spans the interval between dead-time pulses, and circuits that average the value of these pulses over time. The logarithm of each of these values is obtained and the logarithms are subtracted to provide a signal that is proportional to a count rate that is corrected for the effects of dead time. The circuit produces a meter indication and is also capable of producing an audible indication of detected events. 5 figs.

  11. Dead time corrections for inbeam γ-spectroscopy measurements

    NASA Astrophysics Data System (ADS)

    Boromiza, M.; Borcea, C.; Negret, A.; Olacel, A.; Suliman, G.

    2017-08-01

    Relatively high counting rates were registered in a proton inelastic scattering experiment on 16O and 28Si using HPGe detectors which was performed at the Tandem facility of IFIN-HH, Bucharest. In consequence, dead time corrections were needed in order to determine the absolute γ-production cross sections. Considering that the real counting rate follows a Poisson distribution, the dead time correction procedure is reformulated in statistical terms. The arriving time interval between the incoming events (Δt) obeys an exponential distribution with a single parameter - the average of the associated Poisson distribution. We use this mathematical connection to calculate and implement the dead time corrections for the counting rates of the mentioned experiment. Also, exploiting an idea introduced by Pommé et al., we describe a consistent method for calculating the dead time correction which completely eludes the complicated problem of measuring the dead time of a given detection system. Several comparisons are made between the corrections implemented through this method and by using standard (phenomenological) dead time models and we show how these results were used for correcting our experimental cross sections.

  12. Measurement of dead time by time interval distribution method

    NASA Astrophysics Data System (ADS)

    Arkani, Mohammad; Raisali, Gholamreza

    2015-02-01

    Non-random event losses due to dead time effect in nuclear radiation detection systems distort the original Poisson process into a new type of distribution. As the characteristics of the distribution depend on physical properties of the detection system, it is possible to estimate the dead time parameters based on time interval analysis, this is the problem investigated in this work. A BF3 ionization chamber is taken as a case study to check the validity of the method in experiment. The results are compared with the data estimated by power rising experiment performed in Esfahan Heavy Water Zero Power Reactor (EHWZPR). Using Monte Carlo simulation, the problem is elaborately studied and useful range for counting rates of the detector is determined. The proposed method is accurate and applicable for all kinds of radiation detectors with no potential difficulty and no need for any especial nuclear facility. This is not a time consuming method and advanced capability of online examination during normal operation of the detection system is possible.

  13. Dead-time Corrected Disdrometer Data

    DOE Data Explorer

    Bartholomew, Mary Jane

    2008-03-05

    Original and dead-time corrected disdrometer results for observations made at SGP and TWP. The correction is based on the technique discussed in Sheppard and Joe, 1994. In addition, these files contain calculated radar reflectivity factor, mean Doppler velocity and attenuation for every measurement for both the original and dead-time corrected data at the following wavelengths: 0.316, 0.856, 3.2, 5, and 10cm (W,K,X,C,S bands). Pavlos Kollias provided the code to do these calculations.

  14. Theory of particle detection and multiplicity counting with dead time effects

    SciTech Connect

    Pal, L.; Pazsit, I.

    2013-07-01

    The subject of this paper is the investigation of the effect of the dead time on the statistics of the particle detection process. A theoretical treatment is provided with the application of the methods of renewal theory. The detector efficiency and various types of the dead time are accounted for. Exact analytical results are derived for the probability distribution functions, the expectations and the variances of the number of detected particles. Explicit solutions are given for a few representative cases. The results should serve for the evaluation of the measurements in view of the dead time correction effects for the higher moments of the detector counts. (authors)

  15. Dead Time of Single Photon Avalanche Diodes

    NASA Astrophysics Data System (ADS)

    Neri, L.; Tudisco, S.; Musumeci, F.; Scordino, A.; Fallica, G.; Mazzillo, M.; Zimbone, M.

    2011-06-01

    Single Photon Avalanche Diode (SPAD) is the new generation of Geiger-Muller counter device developed in semiconductor technology [S. Privitera et al. Sensors Journal, vol 8 Iss. 8 (2008) 4636; S. Tudisco et al. IEEE Sensors Journal vol 8 ISS 7-8 (2008) 1324; S. Cova et al. Applied Optics 35 (1996) 1956]. Physical dead time model and noise production process has been analyzed and their corrections have been performed [S.H. Lee, R.P. Gardner, M. Jae, Nucl. Instr. and Meth. in Phys. Res. B 263 (2007) 46]. We have been able to extract the real amount of incident photon rate up to 10 7cps using a device with 0.97μs total deadtime. We also developed the equation of the noise count rate vs incoming photon rate, supported by Montecarlo simulation and experimental data. We marked the difference between dark rate and noise count rate, and introduced the noise rate inside the hybrid deadtime equation used for SPAD device.

  16. Zero-dead-time operation of interleaved atomic clocks.

    PubMed

    Biedermann, G W; Takase, K; Wu, X; Deslauriers, L; Roy, S; Kasevich, M A

    2013-10-25

    We demonstrate a zero-dead-time operation of atomic clocks. This clock reduces sensitivity to local oscillator noise, integrating as nearly 1/τ whereas a clock with dead time integrates as 1/τ(1/2) under identical conditions. We contend that a similar scheme may be applied to improve the stability of optical clocks.

  17. Measurement of the dead layer thickness in a p-type point contact germanium detector

    NASA Astrophysics Data System (ADS)

    Jiang, Hao; Yue, Qian; Li, Yu-Lan; Kang, Ke-Jun; Li, Yuan-Jing; Li, Jin; Lin, Shin-Ted; Liu, Shu-Kui; Ma, Hao; Ma, Jing-Lu; Su, Jian; Tsz-King Wong, Henry; Yang, Li-Tao; Zhao, Wei; Zeng, Zhi

    2016-09-01

    A 994 g mass p-type PCGe detector has been deployed during the first phase of the China Dark matter EXperiment, aiming at direct searches for light weakly interacting massive particles. Measuring the thickness of the dead layer of a p-type germanium detector is an issue of major importance since it determines the fiducial mass of the detector. This work reports a method using an uncollimated 133Ba source to determine the dead layer thickness. The experimental design, data analysis and Monte Carlo simulation processes, as well as the statistical and systematic uncertainties are described. A dead layer thickness of 1.02 mm was obtained based on a comparison between the experimental data and the simulated results. Supported by National Natural Science Foundation of China (10935005, 10945002, 11275107, 11175099)

  18. Dead time correction in coincidence counting of photon pairs

    NASA Astrophysics Data System (ADS)

    Kang, M. S.; Lee, D.-H.; Lee, J.; Lee, J. Y.; Choi, S.-K.; Park, H. S.

    2008-08-01

    We describe two methods for evaluating the dead time of a time-to-amplitude converter (TAC). The dead time is obtained by measuring either the corresponding time interval in an oscilloscope trace or the relation between the single count rate and the coincidence count rate. Values for the TAC dead time are obtained in the range from 3.4 µs to 14.3 µs for the two methods with respective standard uncertainties of 2.9 × 10-8 s and 3.3 × 10-9 s. The TAC dead time is applied to the calibration of coincidence-counting measurements of optical transmission and photon-heralding efficiency.

  19. Noise and interpixel dead space studies of GaAs pixellated detectors

    NASA Astrophysics Data System (ADS)

    Abate, L.; Bertolucci, E.; Conti, M.; Mettivier, G.; Montesi, M. C.; Russo, P.

    2001-02-01

    In the framework of the development of a digital radiography/autoradiography system using solid state detectors, we studied the performance of GaAs pixellated detectors regarding noise level and detection behavior of interpixel space. The detector is a 64×64 pixel array, 200 μm thick GaAs, 150 μm contact size and 20 μm interpixel space. Studies involve I- V curves, detector behavior for long-period biasing, noise as a function of temperature, and possible detection efficiency loss due to interpixel dead spaces.

  20. High-rate dead-time corrections in a general purpose digital pulse processing system.

    PubMed

    Abbene, Leonardo; Gerardi, Gaetano

    2015-09-01

    Dead-time losses are well recognized and studied drawbacks in counting and spectroscopic systems. In this work the abilities on dead-time correction of a real-time digital pulse processing (DPP) system for high-rate high-resolution radiation measurements are presented. The DPP system, through a fast and slow analysis of the output waveform from radiation detectors, is able to perform multi-parameter analysis (arrival time, pulse width, pulse height, pulse shape, etc.) at high input counting rates (ICRs), allowing accurate counting loss corrections even for variable or transient radiations. The fast analysis is used to obtain both the ICR and energy spectra with high throughput, while the slow analysis is used to obtain high-resolution energy spectra. A complete characterization of the counting capabilities, through both theoretical and experimental approaches, was performed. The dead-time modeling, the throughput curves, the experimental time-interval distributions (TIDs) and the counting uncertainty of the recorded events of both the fast and the slow channels, measured with a planar CdTe (cadmium telluride) detector, will be presented. The throughput formula of a series of two types of dead-times is also derived. The results of dead-time corrections, performed through different methods, will be reported and discussed, pointing out the error on ICR estimation and the simplicity of the procedure. Accurate ICR estimations (nonlinearity < 0.5%) were performed by using the time widths and the TIDs (using 10 ns time bin width) of the detected pulses up to 2.2 Mcps. The digital system allows, after a simple parameter setting, different and sophisticated procedures for dead-time correction, traditionally implemented in complex/dedicated systems and time-consuming set-ups.

  1. High-rate dead-time corrections in a general purpose digital pulse processing system

    PubMed Central

    Abbene, Leonardo; Gerardi, Gaetano

    2015-01-01

    Dead-time losses are well recognized and studied drawbacks in counting and spectroscopic systems. In this work the abilities on dead-time correction of a real-time digital pulse processing (DPP) system for high-rate high-resolution radiation measurements are presented. The DPP system, through a fast and slow analysis of the output waveform from radiation detectors, is able to perform multi-parameter analysis (arrival time, pulse width, pulse height, pulse shape, etc.) at high input counting rates (ICRs), allowing accurate counting loss corrections even for variable or transient radiations. The fast analysis is used to obtain both the ICR and energy spectra with high throughput, while the slow analysis is used to obtain high-resolution energy spectra. A complete characterization of the counting capabilities, through both theoretical and experimental approaches, was performed. The dead-time modeling, the throughput curves, the experimental time-interval distributions (TIDs) and the counting uncertainty of the recorded events of both the fast and the slow channels, measured with a planar CdTe (cadmium telluride) detector, will be presented. The throughput formula of a series of two types of dead-times is also derived. The results of dead-time corrections, performed through different methods, will be reported and discussed, pointing out the error on ICR estimation and the simplicity of the procedure. Accurate ICR estimations (nonlinearity < 0.5%) were performed by using the time widths and the TIDs (using 10 ns time bin width) of the detected pulses up to 2.2 Mcps. The digital system allows, after a simple parameter setting, different and sophisticated procedures for dead-time correction, traditionally implemented in complex/dedicated systems and time-consuming set-ups. PMID:26289270

  2. Assessment of three dead detector correction methods for cone-beam computed tomography

    SciTech Connect

    Nelms, David W.; Shukla, Hemant I.; Nixon, Earl; Bayouth, John E.; Flynn, Ryan T.

    2009-10-15

    Purpose: Dead detectors due to manufacturing defects or radiation damage in the electronic portal imaging devices (EPIDs) used for cone-beam computed tomography (CBCT) can lead to image degradation and ring artifacts. In this work three dead detector correction methods were assessed using megavoltage CBCT (MVCBCT) as a test system, with the goals of assessing the relative effectiveness of the three methods and establishing the conditions for which they fail. Methods: MVCBCT projections acquired with four linacs at 8 and 60 MU (monitor units) were degraded with varying percentages (2%-95%) of randomly distributed dead single detectors (RDSs), randomly distributed dead detector clusters (RDCs) of 2 mm diameter, and nonrandomly distributed dead detector disks (NRDDs) of varying diameter (4-16 mm). Correction algorithms were bidirectional linear interpolation (BLI), quad-directional linear interpolation (QLI), and a Laplacian solution (LS) method. Correction method failure was defined to occur if ring artifacts were present in the reconstructed phantom images from any linac or if the modulation transfer function (MTF) for any linac dropped below baseline with a p value, calculated with the two sample t test, of less than 0.01. Results: All correction methods failed at the same or lower RDC/RDS percentages and NRDD diameters for the 60 MU as for the 8 MU cases. The LS method tended to outperform or match the BLI and QLI methods. If ring artifacts anywhere in the images were considered unacceptable, the LS method failed for 60 MU at >33% RDS, >2% RDC, and >4 mm NRDD. If ring artifacts within 4 mm longitudinally of the phantom section interfaces were considered acceptable, the LS method failed for 60 MU at >90% RDS, >80% RDC, and >4 mm NRDD. LS failed due to MTF drop for 60 MU at >50% RDS, >25% RDC, and >4 mm NRDD. Conclusions: The LS method is superior to the BLI and QLI methods, and correction algorithm effectiveness decreases as imaging dose increases. All correction

  3. Dead layer on silicon p-i-n diode charged-particle detectors

    SciTech Connect

    Wall, B. L.; Amsbaugh, John F.; Beglarian, A.; Bergmann, T.; Bichsel, H. C.; Bodine, L. I.; Boyd, N. M.; Burritt, Tom H.; Chaoui, Z.; Corona, T. J.; Doe, Peter J.; Enomoto, S.; Harms, F.; Harper, Gregory; Howe, M. A.; Martin, E. L.; Parno, D. S.; Peterson, David; Petzold, Linda; Renschler, R.; Robertson, R. G. H.; Schwarz, J.; Steidl, M.; Van Wechel, T. D.; VanDevender, Brent A.; Wustling, S.; Wierman, K. J.; Wilkerson, J. F.

    2014-04-21

    Abstract Semiconductor detectors in general have a dead layer at their surfaces that is either a result of natural or induced passivation, or is formed during the process of making a contact. Charged particles passing through this region produce ionization that is incompletely collected and recorded, which leads to departures from the ideal in both energy deposition and resolution. The silicon p-i-n diode used in the KATRIN neutrinomass experiment has such a dead layer. We have constructed a detailed Monte Carlo model for the passage of electrons from vacuum into a silicon detector, and compared the measured energy spectra to the predicted ones for a range of energies from 12 to 20 keV. The comparison provides experimental evidence that a substantial fraction of the ionization produced in the "dead" layer evidently escapes by discussion, with 46% being collected in the depletion zone and the balance being neutralized at the contact or by bulk recombination. The most elementary model of a thinner dead layer from which no charge is collected is strongly disfavored.

  4. Improving the counting efficiency in time-correlated single photon counting experiments by dead-time optimization

    SciTech Connect

    Peronio, P.; Acconcia, G.; Rech, I.; Ghioni, M.

    2015-11-15

    Time-Correlated Single Photon Counting (TCSPC) has been long recognized as the most sensitive method for fluorescence lifetime measurements, but often requiring “long” data acquisition times. This drawback is related to the limited counting capability of the TCSPC technique, due to pile-up and counting loss effects. In recent years, multi-module TCSPC systems have been introduced to overcome this issue. Splitting the light into several detectors connected to independent TCSPC modules proportionally increases the counting capability. Of course, multi-module operation also increases the system cost and can cause space and power supply problems. In this paper, we propose an alternative approach based on a new detector and processing electronics designed to reduce the overall system dead time, thus enabling efficient photon collection at high excitation rate. We present a fast active quenching circuit for single-photon avalanche diodes which features a minimum dead time of 12.4 ns. We also introduce a new Time-to-Amplitude Converter (TAC) able to attain extra-short dead time thanks to the combination of a scalable array of monolithically integrated TACs and a sequential router. The fast TAC (F-TAC) makes it possible to operate the system towards the upper limit of detector count rate capability (∼80 Mcps) with reduced pile-up losses, addressing one of the historic criticisms of TCSPC. Preliminary measurements on the F-TAC are presented and discussed.

  5. Improving the counting efficiency in time-correlated single photon counting experiments by dead-time optimization

    PubMed Central

    Peronio, P.; Acconcia, G.; Rech, I.; Ghioni, M.

    2015-01-01

    Time-Correlated Single Photon Counting (TCSPC) has been long recognized as the most sensitive method for fluorescence lifetime measurements, but often requiring “long” data acquisition times. This drawback is related to the limited counting capability of the TCSPC technique, due to pile-up and counting loss effects. In recent years, multi-module TCSPC systems have been introduced to overcome this issue. Splitting the light into several detectors connected to independent TCSPC modules proportionally increases the counting capability. Of course, multi-module operation also increases the system cost and can cause space and power supply problems. In this paper, we propose an alternative approach based on a new detector and processing electronics designed to reduce the overall system dead time, thus enabling efficient photon collection at high excitation rate. We present a fast active quenching circuit for single-photon avalanche diodes which features a minimum dead time of 12.4 ns. We also introduce a new Time-to-Amplitude Converter (TAC) able to attain extra-short dead time thanks to the combination of a scalable array of monolithically integrated TACs and a sequential router. The fast TAC (F-TAC) makes it possible to operate the system towards the upper limit of detector count rate capability (∼80 Mcps) with reduced pile-up losses, addressing one of the historic criticisms of TCSPC. Preliminary measurements on the F-TAC are presented and discussed. PMID:26628115

  6. Improving the counting efficiency in time-correlated single photon counting experiments by dead-time optimization.

    PubMed

    Peronio, P; Acconcia, G; Rech, I; Ghioni, M

    2015-11-01

    Time-Correlated Single Photon Counting (TCSPC) has been long recognized as the most sensitive method for fluorescence lifetime measurements, but often requiring "long" data acquisition times. This drawback is related to the limited counting capability of the TCSPC technique, due to pile-up and counting loss effects. In recent years, multi-module TCSPC systems have been introduced to overcome this issue. Splitting the light into several detectors connected to independent TCSPC modules proportionally increases the counting capability. Of course, multi-module operation also increases the system cost and can cause space and power supply problems. In this paper, we propose an alternative approach based on a new detector and processing electronics designed to reduce the overall system dead time, thus enabling efficient photon collection at high excitation rate. We present a fast active quenching circuit for single-photon avalanche diodes which features a minimum dead time of 12.4 ns. We also introduce a new Time-to-Amplitude Converter (TAC) able to attain extra-short dead time thanks to the combination of a scalable array of monolithically integrated TACs and a sequential router. The fast TAC (F-TAC) makes it possible to operate the system towards the upper limit of detector count rate capability (∼80 Mcps) with reduced pile-up losses, addressing one of the historic criticisms of TCSPC. Preliminary measurements on the F-TAC are presented and discussed.

  7. Improving the counting efficiency in time-correlated single photon counting experiments by dead-time optimization

    NASA Astrophysics Data System (ADS)

    Peronio, P.; Acconcia, G.; Rech, I.; Ghioni, M.

    2015-11-01

    Time-Correlated Single Photon Counting (TCSPC) has been long recognized as the most sensitive method for fluorescence lifetime measurements, but often requiring "long" data acquisition times. This drawback is related to the limited counting capability of the TCSPC technique, due to pile-up and counting loss effects. In recent years, multi-module TCSPC systems have been introduced to overcome this issue. Splitting the light into several detectors connected to independent TCSPC modules proportionally increases the counting capability. Of course, multi-module operation also increases the system cost and can cause space and power supply problems. In this paper, we propose an alternative approach based on a new detector and processing electronics designed to reduce the overall system dead time, thus enabling efficient photon collection at high excitation rate. We present a fast active quenching circuit for single-photon avalanche diodes which features a minimum dead time of 12.4 ns. We also introduce a new Time-to-Amplitude Converter (TAC) able to attain extra-short dead time thanks to the combination of a scalable array of monolithically integrated TACs and a sequential router. The fast TAC (F-TAC) makes it possible to operate the system towards the upper limit of detector count rate capability (˜80 Mcps) with reduced pile-up losses, addressing one of the historic criticisms of TCSPC. Preliminary measurements on the F-TAC are presented and discussed.

  8. Estimating the Effective System Dead Time Parameter for Correlated Neutron Counting

    DOE PAGES

    Croft, Stephen; Cleveland, Steve; Favalli, Andrea; ...

    2017-04-29

    short time, and it yields consistent results as a function of the order of the moment used to extract the dead time parameter. In addition, this latter observation is reassuring in that it suggests the assumptions underpinning the theoretical analysis are fit for practical application purposes. However, we found that the effective dead time parameter obtained is not constant, as might be expected for a parameter that in the dead time model is characteristic of the detector system, but rather, varies systematically with gate width.« less

  9. Coding for Communication Channels with Dead-Time Constraints

    NASA Technical Reports Server (NTRS)

    Moision, Bruce; Hamkins, Jon

    2004-01-01

    Coding schemes have been designed and investigated specifically for optical and electronic data-communication channels in which information is conveyed via pulse-position modulation (PPM) subject to dead-time constraints. These schemes involve the use of error-correcting codes concatenated with codes denoted constrained codes. These codes are decoded using an interactive method. In pulse-position modulation, time is partitioned into frames of Mslots of equal duration. Each frame contains one pulsed slot (all others are non-pulsed). For a given channel, the dead-time constraints are defined as a maximum and a minimum on the allowable time between pulses. For example, if a Q-switched laser is used to transmit the pulses, then the minimum allowable dead time is the time needed to recharge the laser for the next pulse. In the case of bits recorded on a magnetic medium, the minimum allowable time between pulses depends on the recording/playback speed and the minimum distance between pulses needed to prevent interference between adjacent bits during readout. The maximum allowable dead time for a given channel is the maximum time for which it is possible to satisfy the requirement to synchronize slots. In mathematical shorthand, the dead-time constraints for a given channel are represented by the pair of integers (d,k), where d is the minimum allowable number of zeroes between ones and k is the maximum allowable number of zeroes between ones. A system of the type to which the present schemes apply is represented by a binary- input, real-valued-output channel model illustrated in the figure. At the transmitting end, information bits are first encoded by use of an error-correcting code, then further encoded by use of a constrained code. Several constrained codes for channels subject to constraints of (d,infinity) have been investigated theoretically and computationally. The baseline codes chosen for purposes of comparison were simple PPM codes characterized by M-slot PPM

  10. Detector response in time-of-flight mass spectrometry at high pulse repetition frequencies

    NASA Technical Reports Server (NTRS)

    Gulcicek, Erol E.; Boyle, James G.

    1993-01-01

    Dead time effects in chevron configured dual microchannel plates (MCPs) are investigated. Response times are determined experimentally for one chevron-configured dual MCP-type detector and two discrete dynode-type electron multipliers with 16 and 23 resistively divided stages. All of these detectors are found to be suitable for time-of-flight mass spectrometry (TOF MS), yielding 3-6-ns (FWHM) response times triggered on a single ion pulse. It is concluded that, unless there are viable solutions to overcome dead time disadvantages for continuous dynode detectors, suitable discrete dynode detectors for TOF MS appear to have a significant advantage for high repetition rate operation.

  11. SU-E-I-88: The Effect of System Dead Time On Real-Time Plastic and GOS Based Fiber-Optic Dosimetry Systems

    SciTech Connect

    Hoerner, M; Hintenlang, D

    2015-06-15

    Purpose: A methodology is presented to correct for measurement inaccuracies at high detector count rates using a plastic and GOS scintillation fibers coupled to a photomultiplier tube with digital readout. This system allows temporal acquisition and manipulation of measured data. Methods: The detection system used was a plastic scintillator and a separate gadolinium scintillator, both (0.5 diameter) coupled to an optical fiber with a Hamamatsu photon counter with a built-in microcontroller and digital interface. Count rate performance of the system was evaluated using the nonparalzable detector model. Detector response was investigated across multiple radiation sources including: orthovoltage x-ray system, colbat-60 gamma rays, proton therapy beam, and a diagnostic radiography x-ray tube. The dead time parameter was calculated by measuring the count rate of the system at different exposure rates using a reference detector. Results: The system dead time was evaluated for the following sources of radiation used clinically: diagnostic energy x-rays, cobalt-60 gamma rays, orthovoltage xrays, particle proton accelerator, and megavoltage x-rays. It was found that dead time increased significantly when exposing the detector to sources capable of generating Cerenkov radiation, all of the sources sans the diagnostic x-rays, with increasing prominence at higher photon energies. Percent depth dose curves generated by a dedicated ionization chamber and compared to the detection system demonstrated that correcting for dead time improves accuracy. On most sources, nonparalzable model fit provided an improved system response. Conclusion: Overall, the system dead time was variable across the investigated radiation particles and energies. It was demonstrated that the system response accuracy was greatly improved by correcting for dead time effects. Cerenkov radiation plays a significant role in the increase in the system dead time through transient absorption effects attributed to

  12. Pulse-height defect due to electron interaction in dead layers of Ge/Li/ gamma-ray detectors

    NASA Technical Reports Server (NTRS)

    Larsen, R. N.; Strauss, M. G.

    1969-01-01

    Study shows the pulse-height degradation of gamma ray spectra in germanium/lithium detectors to be due to electron interaction in the dead layers that exist in all semiconductor detectors. A pulse shape discrimination technique identifies and eliminates these defective pulses.

  13. Minimizing guard ring dead space in silicon detectors with an n-type guard ring at the edge of the detector

    NASA Astrophysics Data System (ADS)

    Palviainen, Tanja; Tuuva, Tuure; Leinonen, Kari

    2007-04-01

    Detectors with n-type silicon with an n +-type guard ring were investigated. In the present work, a new p +/n/n + detector structure with an n + guard ring is described. The guard ring is placed at the edge of the detector. The detector depletion region extends also sideways, allowing for signal collection very close to the n-guard ring. In this kind of detector structure, the dead space of the detector is minimized to be only below the guard ring. This is proved by simulations done using Silvaco/ATLAS software.

  14. No Time for Dead Time: Timing Analysis of Bright Black Hole Binaries with NuSTAR

    NASA Astrophysics Data System (ADS)

    Bachetti, Matteo; Harrison, Fiona A.; Cook, Rick; Tomsick, John; Schmid, Christian; Grefenstette, Brian W.; Barret, Didier; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Fabian, Andrew C.; Fürst, Felix; Gandhi, Poshak; Hailey, Charles J.; Kara, Erin; Maccarone, Thomas J.; Miller, Jon M.; Pottschmidt, Katja; Stern, Daniel; Uttley, Phil; Walton, Dominic J.; Wilms, Jörn; Zhang, William W.

    2015-02-01

    Timing of high-count-rate sources with the NuSTAR Small Explorer Mission requires specialized analysis techniques. NuSTAR was primarily designed for spectroscopic observations of sources with relatively low count rates rather than for timing analysis of bright objects. The instrumental dead time per event is relatively long (~2.5 msec) and varies event-to-event by a few percent. The most obvious effect is a distortion of the white noise level in the power density spectrum (PDS) that cannot be easily modeled with standard techniques due to the variable nature of the dead time. In this paper, we show that it is possible to exploit the presence of two completely independent focal planes and use the cospectrum, the real part of the cross PDS, to obtain a good proxy of the white-noise-subtracted PDS. Thereafter, one can use a Monte Carlo approach to estimate the remaining effects of dead time, namely, a frequency-dependent modulation of the variance and a frequency-independent drop of the sensitivity to variability. In this way, most of the standard timing analysis can be performed, albeit with a sacrifice in signal-to-noise ratio relative to what would be achieved using more standard techniques. We apply this technique to NuSTAR observations of the black hole binaries GX 339-4, Cyg X-1, and GRS 1915+105.

  15. NO TIME FOR DEAD TIME: TIMING ANALYSIS OF BRIGHT BLACK HOLE BINARIES WITH NuSTAR

    SciTech Connect

    Bachetti, Matteo; Barret, Didier; Harrison, Fiona A.; Cook, Rick; Grefenstette, Brian W.; Fürst, Felix; Tomsick, John; Boggs, Steven E.; Craig, William W.; Schmid, Christian; Christensen, Finn E.; Fabian, Andrew C.; Kara, Erin; Gandhi, Poshak; Hailey, Charles J.; Maccarone, Thomas J.; Miller, Jon M.; Pottschmidt, Katja; Stern, Daniel; Uttley, Phil; and others

    2015-02-20

    Timing of high-count-rate sources with the NuSTAR Small Explorer Mission requires specialized analysis techniques. NuSTAR was primarily designed for spectroscopic observations of sources with relatively low count rates rather than for timing analysis of bright objects. The instrumental dead time per event is relatively long (∼2.5 msec) and varies event-to-event by a few percent. The most obvious effect is a distortion of the white noise level in the power density spectrum (PDS) that cannot be easily modeled with standard techniques due to the variable nature of the dead time. In this paper, we show that it is possible to exploit the presence of two completely independent focal planes and use the cospectrum, the real part of the cross PDS, to obtain a good proxy of the white-noise-subtracted PDS. Thereafter, one can use a Monte Carlo approach to estimate the remaining effects of dead time, namely, a frequency-dependent modulation of the variance and a frequency-independent drop of the sensitivity to variability. In this way, most of the standard timing analysis can be performed, albeit with a sacrifice in signal-to-noise ratio relative to what would be achieved using more standard techniques. We apply this technique to NuSTAR observations of the black hole binaries GX 339–4, Cyg X-1, and GRS 1915+105.

  16. Re-evaluation of Galileo Energetic Particle Detector data - a correction model and comparison to semiconductor detector dead-layer sensitivity losses using SRIM

    NASA Astrophysics Data System (ADS)

    Lee-Payne, Zoe Hannah

    2016-10-01

    The Energetic Particle Detector launched in 1989 on the Galileo satellite took data on the Jovian Particle environment for 8 years before its demise. Over the course of the mission the detectors in the Composition Measurement System (CMS) have visibly decayed with higher mass particles, specifically oxygen and sulphur, reading far lower energies at later epochs. By considering the non-steady accumulation of damage in the detector, as well as the operation of the priority channel data recording system in place on the EPD, an evolving correction can be made. The recalibration significance can be validated using a model of dead layer build-up in semiconductor detectors, based on SRIM results. The final aim is to assign an estimation dead-layer depth during the mission data recordings.

  17. Active cancellation - A means to zero dead-time pulse EPR

    NASA Astrophysics Data System (ADS)

    Franck, John M.; Barnes, Ryan P.; Keller, Timothy J.; Kaufmann, Thomas; Han, Songi

    2015-12-01

    The necessary resonator employed in pulse electron paramagnetic resonance (EPR) rings after the excitation pulse and creates a finite detector dead-time that ultimately prevents the detection of signal from fast relaxing spin systems, hindering the application of pulse EPR to room temperature measurements of interesting chemical or biological systems. We employ a recently available high bandwidth arbitrary waveform generator (AWG) to produce a cancellation pulse that precisely destructively interferes with the resonant cavity ring-down. We find that we can faithfully detect EPR signal at all times immediately after, as well as during, the excitation pulse. This is a proof of concept study showcasing the capability of AWG pulses to precisely cancel out the resonator ring-down, and allow for the detection of EPR signal during the pulse itself, as well as the dead-time of the resonator. However, the applicability of this approach to conventional EPR experiments is not immediate, as it hinges on either (1) the availability of low-noise microwave sources and amplifiers to produce the necessary power for pulse EPR experiment or (2) the availability of very high conversion factor micro coil resonators that allow for pulse EPR experiments at modest microwave power.

  18. Active cancellation - A means to zero dead-time pulse EPR.

    PubMed

    Franck, John M; Barnes, Ryan P; Keller, Timothy J; Kaufmann, Thomas; Han, Songi

    2015-12-01

    The necessary resonator employed in pulse electron paramagnetic resonance (EPR) rings after the excitation pulse and creates a finite detector dead-time that ultimately prevents the detection of signal from fast relaxing spin systems, hindering the application of pulse EPR to room temperature measurements of interesting chemical or biological systems. We employ a recently available high bandwidth arbitrary waveform generator (AWG) to produce a cancellation pulse that precisely destructively interferes with the resonant cavity ring-down. We find that we can faithfully detect EPR signal at all times immediately after, as well as during, the excitation pulse. This is a proof of concept study showcasing the capability of AWG pulses to precisely cancel out the resonator ring-down, and allow for the detection of EPR signal during the pulse itself, as well as the dead-time of the resonator. However, the applicability of this approach to conventional EPR experiments is not immediate, as it hinges on either (1) the availability of low-noise microwave sources and amplifiers to produce the necessary power for pulse EPR experiment or (2) the availability of very high conversion factor micro coil resonators that allow for pulse EPR experiments at modest microwave power.

  19. Time domain electromagnetic metal detectors

    SciTech Connect

    Hoekstra, P.

    1996-04-01

    This presentation focuses on illustrating by case histories the range of applications and limitations of time domain electromagnetic (TDEM) systems for buried metal detection. Advantages claimed for TDEM metal detectors are: independent of instrument response (Geonics EM61) to surrounding soil and rock type; simple anomaly shape; mitigation of interference by ambient electromagnetic noise; and responsive to both ferrous and non-ferrous metallic targets. The data in all case histories to be presented were acquired with the Geonics EM61 TDEM system. Case histories are a test bed site on Molokai, Hawaii; Fort Monroe, Virginia; and USDOE, Rocky Flats Plant. The present limitations of this technology are: discrimination capabilities in terms of type of ordnance, and depth of burial is limited, and ability of resolving targets with small metallic ambient needs to be improved.

  20. Experimental evaluation of the extended Dytlewski-style dead time correction formalism for neutron multiplicity counting

    DOE PAGES

    Lockhart, M.; Henzlova, D.; Croft, S.; ...

    2017-09-20

    Over the past few decades, neutron multiplicity counting has played an integral role in Special Nuclear Material (SNM) characterization pertaining to nuclear safeguards. Current neutron multiplicity analysis techniques use singles, doubles, and triples count rates because a methodology to extract and dead time correct higher order count rates (i.e. quads and pents) was not fully developed. This limitation is overcome by the recent extension of a popular dead time correction method developed by Dytlewski. This extended dead time correction algorithm, named Dytlewski-Croft-Favalli (DCF), is detailed in reference Croft and Favalli (2017), which gives an extensive explanation of the theory andmore » implications of this new development. Dead time corrected results can then be used to assay SNM by inverting a set of extended point model equations which as well have only recently been formulated. Here, we discuss and present the experimental evaluation of practical feasibility of the DCF dead time correction algorithm to demonstrate its performance and applicability in nuclear safeguards applications. In order to test the validity and effectiveness of the dead time correction for quads and pents, 252Cf and SNM sources were measured in high efficiency neutron multiplicity counters at the Los Alamos National Laboratory (LANL) and the count rates were extracted up to the fifth order and corrected for dead time. To assess the DCF dead time correction, the corrected data is compared to traditional dead time correction treatment within INCC. The DCF dead time correction is found to provide adequate dead time treatment for broad range of count rates available in practical applications.« less

  1. Live-timer method of automatic dead-time correction for precision counting

    NASA Technical Reports Server (NTRS)

    Porges, K. G.; Rudnick, S. J.

    1969-01-01

    Automatic correction for dead time losses in nuclear counting experiments is implemented by a simple live timer arrangement in which each counting interval is extended for compensation for the dead time during that interval. this method eliminates repetitious manual calculations, source of error, and dependence upon paralysis shifts.

  2. Examining the Impact of External Influences on Police Use of Deadly Force over Time.

    ERIC Educational Resources Information Center

    White, Michael D.

    2002-01-01

    Used interrupted time-series analysis (ARIMA) to study the impact of legislation and judicial intervention on the use of deadly force by police officers in Philadelphia, Pennsylvania. Findings generally suggest that dynamic changes in the internal working environment can outweigh the influence of external mechanisms on deadly force use. Findings…

  3. Long-Time Sustainability of Rossby Wave Instability in Protoplanetary Disks with Dead Zone

    NASA Astrophysics Data System (ADS)

    Li, S.; Li, H.

    2015-10-01

    We have run 2D simulations to investigate the generation and sustainability of Rossby wave instability (RWI) in proto-planetary disks with constant viscosity and for disks with low viscosity regions (dead zone). For the constant viscosity case, the development of RWI requires a low viscosity and life time of the RWI is short. We also find that the vortex, when it migrates, does so much faster than the disk's viscous drift rate. For disks with dead zone case, a much larger viscosity can be used and the RWI vortex can be sustained for a long time, even the life time of the disk, depending on the width and depth of the dead zone. For a narrow dead zone, the vortex depicts a periodic pattern with a period inversely proportional to the viscosity. If the dead-zone width exceeds some threshold, the periodicity of the RWI disappears.

  4. Simulation of Rate-Related (Dead-Time) Losses In Passive Neutron Multiplicity Counting Systems

    SciTech Connect

    Evans, L.G.; Norman, P.I.; Leadbeater, T.W.; Croft, S.; Philips, S.

    2008-07-01

    Passive Neutron Multiplicity Counting (PNMC) based on Multiplicity Shift Register (MSR) electronics (a form of time correlation analysis) is a widely used non-destructive assay technique for quantifying spontaneously fissile materials such as Pu. At high event rates, dead-time losses perturb the count rates with the Singles, Doubles and Triples being increasingly affected. Without correction these perturbations are a major source of inaccuracy in the measured count rates and assay values derived from them. This paper presents the simulation of dead-time losses and investigates the effect of applying different dead-time models on the observed MSR data. Monte Carlo methods have been used to simulate neutron pulse trains for a variety of source intensities and with ideal detection geometry, providing an event by event record of the time distribution of neutron captures within the detection system. The action of the MSR electronics was modelled in software to analyse these pulse trains. Stored pulse trains were perturbed in software to apply the effects of dead-time according to the chosen physical process; for example, the ideal paralysable (extending) and non-paralysable models with an arbitrary dead-time parameter. Results of the simulations demonstrate the change in the observed MSR data when the system dead-time parameter is varied. In addition, the paralysable and non-paralysable models of deadtime are compared. These results form part of a larger study to evaluate existing dead-time corrections and to extend their application to correlated sources. (authors)

  5. Fast-timing methods for semiconductor detectors

    SciTech Connect

    Spieler, H.

    1982-03-01

    The basic parameters are discussed which determine the accuracy of timing measurements and their effect in a practical application, specifically timing with thin-surface barrier detectors. The discussion focusses on properties of the detector, low-noise amplifiers, trigger circuits and time converters. New material presented in this paper includes bipolar transistor input stages with noise performance superior to currently available FETs, noiseless input terminations in sub-nanosecond preamplifiers and methods using transmission lines to couple the detector to remotely mounted preamplifiers. Trigger circuits are characterized in terms of effective rise time, equivalent input noise and residual jitter.

  6. Fast timing methods for semiconductor detectors. Revision

    SciTech Connect

    Spieler, H.

    1984-10-01

    This tutorial paper discusses the basic parameters which determine the accuracy of timing measurements and their effect in a practical application, specifically timing with thin-surface barrier detectors. The discussion focusses on properties of the detector, low-noise amplifiers, trigger circuits and time converters. New material presented in this paper includes bipolar transistor input stages with noise performance superior to currently available FETs, noiseless input terminations in sub-nanosecond preamplifiers and methods using transmission lines to couple the detector to remotely mounted preamplifiers. Trigger circuits are characterized in terms of effective rise time, equivalent input noise and residual jitter.

  7. A population coding account for systematic variation in saccadic dead time.

    PubMed

    Ludwig, Casimir J H; Mildinhall, John W; Gilchrist, Iain D

    2007-01-01

    During movement programming, there is a point in time at which the movement system is committed to executing an action with certain parameters even though new information may render this action obsolete. For saccades programmed to a visual target this period is termed the dead time. Using a double-step paradigm, we examined potential variability in the dead time with variations in overall saccade latency and spatiotemporal configuration of two sequential targets. In experiment 1, we varied overall saccade latency by manipulating the presence or absence of a central fixation point. Despite a large and robust gap effect, decreasing the saccade latency in this way did not alter the dead time. In experiment 2, we varied the separation between the two targets. The dead time increased with separation up to a point and then leveled off. A stochastic accumulator model of the oculomotor decision mechanism accounts comprehensively for our findings. The model predicts a gap effect through changes in baseline activity without producing variations in the dead time. Variations in dead time with separation between the two target locations are a natural consequence of the population coding assumption in the model.

  8. Examining the impact of external influences on police use of deadly force over time.

    PubMed

    White, Michael D

    2003-02-01

    Prior deadly force research has sought to identify appropriate mechanisms that can effectively control police officers' decisions to use deadly force. However, the relative impact of external discretion control policies on police shooting behavior remains largely unknown. Using data from Philadelphia for a period of more than two decades, this article employs interrupted time-series analysis (ARIMA) to examine the impact of legislation and judicial intervention on use of deadly force by Philadelphia police officers. The article also considers the impact of larger, community-level characteristics on levels of deadly force. Findings produced modest support for the potential effect of external discretion control policies and community-level factors on police shooting behavior but generally suggest that dynamic changes in the internal working environment can outweigh the influence of the external mechanisms.

  9. Monitoring Dead Space in Mechanically Ventilated Children: Volumetric Capnography Versus Time-Based Capnography.

    PubMed

    Bhalla, Anoopindar K; Rubin, Sarah; Newth, Christopher J L; Ross, Patrick; Morzov, Rica; Soto-Campos, Gerardo; Khemani, Robinder

    2015-11-01

    Volumetric capnography dead-space measurements (physiologic dead-space-to-tidal-volume ratio [VD/VT] and alveolar VD/VT) are considered more accurate than the more readily available time-based capnography dead-space measurement (end-tidal alveolar dead-space fraction [AVDSF]). We sought to investigate the correlation between volumetric capnography and time-based capnography dead-space measurements. This was a single-center prospective cohort study of 65 mechanically ventilated children with arterial lines. Physiologic VD/VT, alveolar VD/VT, and AVDSF were calculated with each arterial blood gas using capnography data. We analyzed 534 arterial blood gases from 65 children (median age 4.9 y, interquartile range 1.7-12.8). The correlation between physiologic VD/VT and AVDSF (r = 0.66, 95% CI 0.59-0.72) was weaker than the correlation between alveolar VD/VT and AVDSF (r = 0.8, 95% CI 0.76-0.85). The correlation between physiologic VD/VT and AVDSF was weaker in children with low PaO2 /FIO2 (< 200 mm Hg), low exhaled VT (< 100 mL), a pulmonary reason for mechanical ventilation, or large airway VD (> 3 mL/kg). All 3 dead-space measurements were highly correlated (r > 0.7) in children without hypoxemia (PaO2 /FIO2 > 300 mm Hg), mechanically ventilated for a neurologic or cardiac reason, or on significant inotropes or vasopressors. In mechanically ventilated children without significant hypoxemia or with cardiac output-related dead-space changes, physiologic VD/VT was highly correlated with AVDSF and alveolar VD/VT. In children with significant hypoxemia, physiologic VD/VT was poorly correlated with AVDSF. Alveolar VD/VT and AVDSF correlated well in most tested circumstances. Therefore, AVDSF may be useful in most children for alveolar dead-space monitoring. Copyright © 2015 by Daedalus Enterprises.

  10. Diamond detectors for the TOTEM timing upgrade

    NASA Astrophysics Data System (ADS)

    Antchev, G.; Aspell, P.; Atanassov, I.; Avati, V.; Baechler, J.; Berardi, V.; Berretti, M.; Bossini, E.; Bottigli, U.; Bozzo, M.; Broulím, P.; Buzzo, A.; Cafagna, F. S.; Catanesi, M. G.; Csanád, M.; Csörgő, T.; Deile, M.; De Leonardis, F.; D'Orazio, A.; Doubek, M.; Eggert, K.; Eremin, V.; Ferro, F.; Fiergolski, A.; Garcia, F.; Georgiev, V.; Giani, S.; Grzanka, L.; Guaragnella, C.; Hammerbauer, J.; Heino, J.; Karev, A.; Kašpar, J.; Kopal, J.; Kundrát, V.; Lami, S.; Latino, G.; Lauhakangas, R.; Linhart, R.; Lokajíček, M. V.; Losurdo, L.; Lo Vetere, M.; Rodríguez, F. Lucas; Lucsanyi, D.; Macrí, M.; Mercadante, A.; Minafra, N.; Minutoli, S.; Naaranoja, T.; Nemes, F.; Niewiadomski, H.; Novak, T.; Oliveri, E.; Oljemark, F.; Oriunno, M.; Österberg, K.; Palazzi, P.; Paločko, L.; Passaro, V.; Peroutka, Z.; Petruzzelli, V.; Politi, T.; Procházka, J.; Prudenzano, F.; Quinto, M.; Radermacher, E.; Radicioni, E.; Ravotti, F.; Robutti, E.; Royon, C.; Ruggiero, G.; Saarikko, H.; Scribano, A.; Smajek, J.; Snoeys, W.; Sziklai, J.; Taylor, C.; Turini, N.; Vacek, V.; Welti, J.; Wyszkowski, P.; Zielinski, K.

    2017-03-01

    This paper describes the design and the performance of the timing detector developed by the TOTEM Collaboration for the Roman Pots (RPs) to measure the Time-Of-Flight (TOF) of the protons produced in central diffractive interactions at the LHC . The measurement of the TOF of the protons allows the determination of the longitudinal position of the proton interaction vertex and its association with one of the vertices reconstructed by the CMS detectors. The TOF detector is based on single crystal Chemical Vapor Deposition (scCVD) diamond plates and is designed to measure the protons TOF with about 50 ps time precision. This upgrade to the TOTEM apparatus will be used in the LHC run 2 and will tag the central diffractive events up to an interaction pileup of about 1. A dedicated fast and low noise electronics for the signal amplification has been developed. The digitization of the diamond signal is performed by sampling the waveform. After introducing the physics studies that will most profit from the addition of these new detectors, we discuss in detail the optimization and the performance of the first TOF detector installed in the LHC in November 2015.

  11. Diamond detectors for the TOTEM timing upgrade

    DOE PAGES

    Antchev, G.; Aspell, P.; Atanassov, I.; ...

    2017-03-09

    This paper describes the design and the performance of the timing detector developed by the TOTEM Collaboration for the Roman Pots (RPs) to measure the Time-Of-Flight (TOF) of the protons produced in central diffractive interactions at the LHC . The measurement of the TOF of the protons allows the determination of the longitudinal position of the proton interaction vertex and its association with one of the vertices reconstructed by the CMS detectors. The TOF detector is based on single crystal Chemical Vapor Deposition (scCVD) diamond plates and is designed to measure the protons TOF with about 50 ps time precision.more » This upgrade to the TOTEM apparatus will be used in the LHC run 2 and will tag the central diffractive events up to an interaction pileup of about 1. A dedicated fast and low noise electronics for the signal amplification has been developed. The digitization of the diamond signal is performed by sampling the waveform. In conclusion, after introducing the physics studies that will most profit from the addition of these new detectors, we discuss in detail the optimization and the performance of the first TOF detector installed in the LHC in November 2015.« less

  12. Corrections for the combined effects of decay and dead time in live-timed counting of short-lived radionuclides.

    PubMed

    Fitzgerald, R

    2016-03-01

    Studies and calibrations of short-lived radionuclides, for example (15)O, are of particular interest in nuclear medicine. Yet counting experiments on such species are vulnerable to an error due to the combined effect of decay and dead time. Separate decay corrections and dead-time corrections do not account for this issue. Usually counting data are decay-corrected to the start time of the count period, or else instead of correcting the count rate, the mid-time of the measurement is used as the reference time. Correction factors are derived for both those methods, considering both extending and non-extending dead time. Series approximations are derived here and the accuracy of those approximations are discussed. Published by Elsevier Ltd.

  13. Utilization of Baeten's Dead-Time Correction Formalism for Multiplicity Counting

    SciTech Connect

    Gavron, A.

    1999-07-12

    We evaluate a dead-time correction formalism for double and triple coincidences in multiplicity counting. We will describe the accuracy by which S (singles), D (doubles), and T (triples) (and consequently, the mass, multiplication, and alpha) of fissile material samples can be determined using this formalism.

  14. On-line compensation of dead-time and inverter nonlinearity with disturbance voltage observer

    NASA Astrophysics Data System (ADS)

    Lee, Beomseok; Kwon, Jung-Min; Kim, Jaehong

    2014-03-01

    This paper discusses and analyses a simple on-line compensation scheme for dead-time and inverter nonlinearity in the pulse width modulated (PWM) voltage source inverter (VSI). Dead-time effect and voltage drop in switching devices cause nonlinearity between reference and output voltage. In a conventional three-phase six-switch inverter, this nonideal condition adds extraneous harmonics that badly disturb voltage characteristics. In its turn, voltage disturbance causes distortion of the current waveform and degrades performance. In this paper, an on-line dead-time compensation method based on inverse dynamics control is proposed, and it is much simpler than conventional full/reduced order observation methods adopted in dead-time compensation. Disturbance voltages are observed on-line with no additional circuitry or off-line measurements. The observed disturbance voltages are fed back to the voltage reference for compensation. Stability problem of the proposed observer arisen from inverter delay and parameter mismatch was analysed. The proposed method is applied to a surface-mounted permanent-magnet synchronous motor (SPMSM) drive. The effectiveness of the proposed scheme is validated by the experimental results.

  15. Extension of the Dytlewski-style dead time correction formalism for neutron multiplicity counting to any order

    DOE PAGES

    Croft, Stephen; Favalli, Andrea

    2017-07-16

    Here, neutron multiplicity counting using shift-register calculus is an established technique in the science of international nuclear safeguards for the identification, verification, and assay of special nuclear materials. Typically passive counting is used for Pu and mixed Pu-U items and active methods are used for U materials. Three measured counting rates, singles, doubles and triples are measured and, in combination with a simple analytical point-model, are used to calculate characteristics of the measurement item in terms of known detector and nuclear parameters. However, the measurement problem usually involves more than three quantities of interest, but even in cases where themore » next higher order count rate, quads, is statistically viable, it is not quantitatively applied because corrections for dead time losses are currently not available in the predominant analysis paradigm. In this work we overcome this limitation by extending the commonly used dead time correction method, developed by Dytlewski, to quads. We also give results for pents, which may be of interest for certain special investigations. Extension to still higher orders, may be accomplished by inspection based on the sequence presented. We discuss the foundations of the Dytlewski method, give limiting cases, and highlight the opportunities and implications that these new results expose. In particular there exist a number of ways in which the new results may be combined with other approaches to extract the correlated rates, and this leads to various practical implementations.« less

  16. Extension of the Dytlewski-style dead time correction formalism for neutron multiplicity counting to any order

    NASA Astrophysics Data System (ADS)

    Croft, Stephen; Favalli, Andrea

    2017-10-01

    Neutron multiplicity counting using shift-register calculus is an established technique in the science of international nuclear safeguards for the identification, verification, and assay of special nuclear materials. Typically passive counting is used for Pu and mixed Pu-U items and active methods are used for U materials. Three measured counting rates, singles, doubles and triples are measured and, in combination with a simple analytical point-model, are used to calculate characteristics of the measurement item in terms of known detector and nuclear parameters. However, the measurement problem usually involves more than three quantities of interest, but even in cases where the next higher order count rate, quads, is statistically viable, it is not quantitatively applied because corrections for dead time losses are currently not available in the predominant analysis paradigm. In this work we overcome this limitation by extending the commonly used dead time correction method, developed by Dytlewski, to quads. We also give results for pents, which may be of interest for certain special investigations. Extension to still higher orders, may be accomplished by inspection based on the sequence presented. We discuss the foundations of the Dytlewski method, give limiting cases, and highlight the opportunities and implications that these new results expose. In particular there exist a number of ways in which the new results may be combined with other approaches to extract the correlated rates, and this leads to various practical implementations.

  17. 32 bin near-infrared time-multiplexing detector with attojoule single-shot energy resolution.

    PubMed

    Eraerds, Patrick; Pomarico, Enrico; Zhang, Jun; Sanguinetti, Bruno; Thew, Rob; Zbinden, Hugo

    2010-10-01

    We present two implementations of photon counting time-multiplexing detectors for near-infrared wavelengths, based on Peltier cooled InGaAs/InP avalanche photodiodes. A first implementation is motivated by practical considerations using only commercially available components. It features 16 bins, pulse repetition rates of up to 22 kHz, and a large range of applicable pulse widths of up to 100 ns. A second implementation is based on rapid gating detectors, permitting dead times below 10 ns. This allows one to realize a high dynamic-range 32 bin detector, able to process pulse repetition rates of up to 6 MHz for pulse widths of up to 200 ps. Analysis of the detector response at 16.5% detection efficiency reveals a single-shot energy resolution on the attojoule level.

  18. The CDF Time of Flight Detector

    SciTech Connect

    S. Cabrera et al.

    2004-01-06

    A new Time of Flight (TOF) detector based on scintillator bars with fine-mesh photomultipliers at both ends has been in operation since 2001 in the CDF experiment. With a design resolution of 100 ps, the TOF can provide separation between K{sup +-} and {pi}{sup +-} in p{bar p} collisions at the 2{omega} level for low momentum, which enhances b flavor tagging capabilities. Because of its very fast response, the TOF is an excellent triggering device, and it is used to trigger on highly ionizing particles, multiple minimum ionizing particles and cosmic rays. Particle identification is achieved by comparing the time-of-flight of the particle measured by the TOF to the time expected for a given mass hypothesis. In order to obtain the resolution necessary for particle ID, optimal calibrations are critical. This paper describes the TOF detector, its calibration procedure, the achieved resolution, the long term operation performances and some of the first results from data analysis using this detector.

  19. Time expanding multihit TDC for the BELLE TOF detector at the KEK B-factory

    SciTech Connect

    Varner, G.; Kichimi, H.; Yamaguchi, H.

    1997-12-31

    Utilizing a time expansion technique, a multihit TDC has been developed for readout of the BELLE TOF detector at the KEK B-Factory. Time digitization consists of three steps: tagging an input signal with respect to a beam collision synchronized reference clock, expansion of this time interval, and readout by a conventional multihit TDC. Using a time expansion factor of 20 and a multihit TDC with a 500 ps LSB, this system provides a precision TOF measurement of 25 ps LSB, {approximately}20 ps resolution, and with a dead time of less than 1 {mu}s.

  20. The TORCH time-of-flight detector

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    The TORCH time-of-flight detector is being developed to provide particle identification between 2 and 10 GeV/c momentum over a flight distance of 10 m. TORCH is designed for large-area coverage, up to 30 m2, and has a DIRC-like construction. The goal is to achieve a 15 ps time-of-flight resolution per incident particle by combining arrival times from multiple Cherenkov photons produced within quartz radiator plates of 10 mm thickness. A four-year R&D programme is underway with an industrial partner (Photek, UK) to produce 53×53 mm2 Micro-Channel Plate (MCP) detectors for the TORCH application. The MCP-PMT will provide a timing accuracy of 40 ps per photon and it will have a lifetime of up to at least 5 Ccm-2 of integrated anode charge by utilizing an Atomic Layer Deposition (ALD) coating. The MCP will be read out using charge division with customised electronics incorporating the NINO chipset. Laboratory results on prototype MCPs are presented. The construction of a prototype TORCH module and its simulated performance are also described.

  1. Symmetrically biased T/R switches for NMR and MRI with microsecond dead time.

    PubMed

    Brunner, David O; Furrer, Lukas; Weiger, Markus; Baumberger, Werner; Schmid, Thomas; Reber, Jonas; Dietrich, Benjamin E; Wilm, Bertram J; Froidevaux, Romain; Pruessmann, Klaas P

    2016-02-01

    For direct NMR detection and imaging of compounds with very short coherence life times the dead time between radio-frequency (RF) pulse and reception of the free induction decay (FID) is a major limiting factor. It is typically dominated by the transient and recovery times of currently available transmit-receive (T/R) switches and amplification chains. A novel PIN diode-based T/R switch topology is introduced allowing for fast switching by high bias transient currents but nevertheless producing a very low video leakage signal and insertion loss (0.5dB). The low transient spike level in conjunction with the high isolation (75dB) prevent saturation of the preamplifier entirely which consequently does not require time for recovery. Switching between transmission and reception is demonstrated within less than 1μs in bench tests as well as in acquisitions of FIDs and zero echo time (ZTE) images with bandwidths up to 500kHz at 7T. Thereby the 2kW switch exhibited a rise-time of 350ns (10-99%) producing however a total video leakage of below 20mV peak-to-peak and less than -89dBm in-band. The achieved switching time renders the RF pulse itself the dominant contribution to the dead time in which a coherence cannot be observed, thus making pulsed NMR experiments almost time-optimal even for compounds with very short signal life times.

  2. Symmetrically biased T/R switches for NMR and MRI with microsecond dead time

    NASA Astrophysics Data System (ADS)

    Brunner, David O.; Furrer, Lukas; Weiger, Markus; Baumberger, Werner; Schmid, Thomas; Reber, Jonas; Dietrich, Benjamin E.; Wilm, Bertram J.; Froidevaux, Romain; Pruessmann, Klaas P.

    2016-02-01

    For direct NMR detection and imaging of compounds with very short coherence life times the dead time between radio-frequency (RF) pulse and reception of the free induction decay (FID) is a major limiting factor. It is typically dominated by the transient and recovery times of currently available transmit-receive (T/R) switches and amplification chains. A novel PIN diode-based T/R switch topology is introduced allowing for fast switching by high bias transient currents but nevertheless producing a very low video leakage signal and insertion loss (0.5 dB). The low transient spike level in conjunction with the high isolation (75 dB) prevent saturation of the preamplifier entirely which consequently does not require time for recovery. Switching between transmission and reception is demonstrated within less than 1 μs in bench tests as well as in acquisitions of FIDs and zero echo time (ZTE) images with bandwidths up to 500 kHz at 7 T. Thereby the 2 kW switch exhibited a rise-time of 350 ns (10-99%) producing however a total video leakage of below 20 mV peak-to-peak and less than -89 dBm in-band. The achieved switching time renders the RF pulse itself the dominant contribution to the dead time in which a coherence cannot be observed, thus making pulsed NMR experiments almost time-optimal even for compounds with very short signal life times.

  3. Real-Time Accumulative Computation Motion Detectors

    PubMed Central

    Fernández-Caballero, Antonio; López, María Teresa; Castillo, José Carlos; Maldonado-Bascón, Saturnino

    2009-01-01

    The neurally inspired accumulative computation (AC) method and its application to motion detection have been introduced in the past years. This paper revisits the fact that many researchers have explored the relationship between neural networks and finite state machines. Indeed, finite state machines constitute the best characterized computational model, whereas artificial neural networks have become a very successful tool for modeling and problem solving. The article shows how to reach real-time performance after using a model described as a finite state machine. This paper introduces two steps towards that direction: (a) A simplification of the general AC method is performed by formally transforming it into a finite state machine. (b) A hardware implementation in FPGA of such a designed AC module, as well as an 8-AC motion detector, providing promising performance results. We also offer two case studies of the use of AC motion detectors in surveillance applications, namely infrared-based people segmentation and color-based people tracking, respectively. PMID:22303161

  4. A uniform time trade off method for states better and worse than dead: feasibility study of the 'lead time' approach.

    PubMed

    Devlin, Nancy J; Tsuchiya, Aki; Buckingham, Ken; Tilling, Carl

    2011-03-01

    The way time trade off (TTO) values are elicited for states of health considered 'worse than being dead' has important implications for the mean values used in economic evaluation. Conventional approaches to TTO, as used in the UK's 'MVH' value set, are problematic because they require fundamentally different trade-offs tasks for the valuation of states better and worse than dead. This study aims to refine and test the feasibility of a new approach described by Robinson and Spencer (2006. Health Economics 15: 393-402), and to explore the characteristics of the valuation data it generates. The approach introduces a 'lead time' into the TTO, producing a uniform procedure for generating values either >0 or<0. We used this lead time TTO to value 10 moderate to severe EQ-5D states using a sample of the general public (n=109). We conclude that the approach is feasible for use in valuation studies and appears to overcome the discontinuity in values around 0 evident in conventional methods. However, further research is required to resolve the issue of how to handle participants who 'use up' all lead time; to develop ways of controlling for individual time preferences; and to better understand the implications for valuations of states better than dead.

  5. 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.

  6. Fundamental Limits of Scintillation Detector Timing Precision

    PubMed Central

    Derenzo, Stephen E.; Choong, Woon-Seng; Moses, William W.

    2014-01-01

    In this paper we review the primary factors that affect the timing precision of a scintillation detector. Monte Carlo calculations were performed to explore the dependence of the timing precision on the number of photoelectrons, the scintillator decay and rise times, the depth of interaction uncertainty, the time dispersion of the optical photons (modeled as an exponential decay), the photodetector rise time and transit time jitter, the leading-edge trigger level, and electronic noise. The Monte Carlo code was used to estimate the practical limits on the timing precision for an energy deposition of 511 keV in 3 mm × 3 mm × 30 mm Lu2SiO5:Ce and LaBr3:Ce crystals. The calculated timing precisions are consistent with the best experimental literature values. We then calculated the timing precision for 820 cases that sampled scintillator rise times from 0 to 1.0 ns, photon dispersion times from 0 to 0.2 ns, photodetector time jitters from 0 to 0.5 ns fwhm, and A from 10 to 10,000 photoelectrons per ns decay time. Since the timing precision R was found to depend on A−1/2 more than any other factor, we tabulated the parameter B, where R = BA−1/2. An empirical analytical formula was found that fit the tabulated values of B with an rms deviation of 2.2% of the value of B. The theoretical lower bound of the timing precision was calculated for the example of 0.5 ns rise time, 0.1 ns photon dispersion, and 0.2 ns fwhm photodetector time jitter. The lower bound was at most 15% lower than leading-edge timing discrimination for A from 10 to 10,000 photoelectrons/ns. A timing precision of 8 ps fwhm should be possible for an energy deposition of 511 keV using currently available photodetectors if a theoretically possible scintillator were developed that could produce 10,000 photoelectrons/ns. PMID:24874216

  7. Fundamental limits of scintillation detector timing precision.

    PubMed

    Derenzo, Stephen E; Choong, Woon-Seng; Moses, William W

    2014-07-07

    In this paper we review the primary factors that affect the timing precision of a scintillation detector. Monte Carlo calculations were performed to explore the dependence of the timing precision on the number of photoelectrons, the scintillator decay and rise times, the depth of interaction uncertainty, the time dispersion of the optical photons (modeled as an exponential decay), the photodetector rise time and transit time jitter, the leading-edge trigger level, and electronic noise. The Monte Carlo code was used to estimate the practical limits on the timing precision for an energy deposition of 511 keV in 3 mm × 3 mm × 30 mm Lu2SiO5:Ce and LaBr3:Ce crystals. The calculated timing precisions are consistent with the best experimental literature values. We then calculated the timing precision for 820 cases that sampled scintillator rise times from 0 to 1.0 ns, photon dispersion times from 0 to 0.2 ns, photodetector time jitters from 0 to 0.5 ns fwhm, and A from 10 to 10,000 photoelectrons per ns decay time. Since the timing precision R was found to depend on A(-1/2) more than any other factor, we tabulated the parameter B, where R = BA(-1/2). An empirical analytical formula was found that fit the tabulated values of B with an rms deviation of 2.2% of the value of B. The theoretical lower bound of the timing precision was calculated for the example of 0.5 ns rise time, 0.1 ns photon dispersion, and 0.2 ns fwhm photodetector time jitter. The lower bound was at most 15% lower than leading-edge timing discrimination for A from 10 to 10,000 photoelectrons ns(-1). A timing precision of 8 ps fwhm should be possible for an energy deposition of 511 keV using currently available photodetectors if a theoretically possible scintillator were developed that could produce 10,000 photoelectrons ns(-1).

  8. Efficient Bell state analyzer for time-bin qubits with fast-recovery WSi superconducting single photon detectors.

    PubMed

    Valivarthi, R; Lucio-Martinez, I; Rubenok, A; Chan, P; Marsili, F; Verma, V B; Shaw, M D; Stern, J A; Slater, J A; Oblak, D; Nam, S W; Tittel, W

    2014-10-06

    We experimentally demonstrate a high-efficiency Bell state measurement for time-bin qubits that employs two superconducting nanowire single-photon detectors with short dead-times, allowing projections onto two Bell states, |ψ⁻〉 and |ψ⁺〉. Compared to previous implementations for time-bin qubits, this yields an increase in the efficiency of Bell state analysis by a factor of thirty.

  9. Simultaneous Analysis of Monovalent Anions and Cations with a Sub-Microliter Dead-Volume Flow-Through Potentiometric Detector for Ion Chromatography

    PubMed Central

    Dumanli, Rukiye; Attar, Azade; Erci, Vildan; Isildak, Ibrahim

    2016-01-01

    A microliter dead-volume flow-through cell as a potentiometric detector is described in this article for sensitive, selective and simultaneous detection of common monovalent anions and cations in single column ion chromatography for the first time. The detection cell consisted of less selective anion- and cation-selective composite membrane electrodes together with a solid-state composite matrix reference electrode. The simultaneous separation and sensitive detection of sodium (Na+), potassium (K+), ammonium (NH4+), chloride (Cl−) and nitrate (NO3−) in a single run was achieved by using 98% 1.5 mM MgSO4 and 2% acetonitrile eluent with a mixed-bed ion-exchange separation column without suppressor column system. The separation and simultaneous detection of the anions and cations were completed in 6 min at the eluent flow-rate of 0.8 mL/min. Detection limits, at S/N = 3, were ranged from 0.2 to 1.0 µM for the anions and 0.3 to 3.0 µM for the cations, respectively. The developed method was successfully applied to the simultaneous determination of monovalent anions and cations in several environmental and biological samples. PMID:26786906

  10. Simultaneous Analysis of Monovalent Anions and Cations with a Sub-Microliter Dead-Volume Flow-Through Potentiometric Detector for Ion Chromatography.

    PubMed

    Dumanli, Rukiye; Attar, Azade; Erci, Vildan; Isildak, Ibrahim

    2016-04-01

    A microliter dead-volume flow-through cell as a potentiometric detector is described in this article for sensitive, selective and simultaneous detection of common monovalent anions and cations in single column ion chromatography for the first time. The detection cell consisted of less selective anion- and cation-selective composite membrane electrodes together with a solid-state composite matrix reference electrode. The simultaneous separation and sensitive detection of sodium (Na(+)), potassium (K(+)), ammonium (NH4 (+)), chloride (Cl(-)) and nitrate (NO3 (-)) in a single run was achieved by using 98% 1.5 mM MgSO4 and 2% acetonitrile eluent with a mixed-bed ion-exchange separation column without suppressor column system. The separation and simultaneous detection of the anions and cations were completed in 6 min at the eluent flow-rate of 0.8 mL/min. Detection limits, at S/N = 3, were ranged from 0.2 to 1.0 µM for the anions and 0.3 to 3.0 µM for the cations, respectively. The developed method was successfully applied to the simultaneous determination of monovalent anions and cations in several environmental and biological samples.

  11. A new Smith predictor and controller for control of processes with long dead time.

    PubMed

    Kaya, Ibrahim

    2003-01-01

    Good control of processes with long dead time is often achieved using a Smith predictor configuration. Typically a PI or PID controller is used; however, it is shown in this paper that for some situations improved set point and disturbance responses can be obtained if a PI-PD controller is used. Several methods are possible for selecting the parameters of the PI-PD controller but when the plant transfer function has no zeros, the use of the standard forms provides a simple algebraic approach, and also reveals why difficulties may be encountered if a PID controller is used. Some examples are given to show the value of the approach presented.

  12. Physical response of light-time gravitational wave detectors

    NASA Astrophysics Data System (ADS)

    Koop, Michael J.; Finn, Lee Samuel

    2014-09-01

    Gravitational wave detectors are typically described as responding to gravitational wave metric perturbations, which are gauge-dependent and—correspondingly—unphysical quantities. This is particularly true for ground-based interferometric detectors, like LIGO, space-based detectors, like LISA and its derivatives, spacecraft Doppler tracking detectors, and pulsar timing array detectors. The description of gravitational waves, and a gravitational wave detector's response, to the unphysical metric perturbation has lead to a proliferation of false analogies and descriptions regarding how these detectors function, and true misunderstandings of the physical character of gravitational waves. Here we provide a fully physical and gauge-invariant description of the response of a wide class of gravitational wave detectors in terms of the Riemann curvature, the physical quantity that describes gravitational phenomena in general relativity. In the limit of high frequency gravitational waves, the Riemann curvature separates into two independent gauge-invariant quantities: a "background" curvature contribution and a "wave" curvature contribution. In this limit the gravitational wave contribution to the detector response reduces to an integral of the gravitational wave contribution of the curvature along the unperturbed photon path between components of the detector. The description presented here provides an unambiguous physical description of what a gravitational wave detector measures and how it operates, a simple means of computing corrections to a detectors response owing to general detector motion, a straightforward way of connecting the results of numerical relativity simulations to gravitational wave detection, and a basis for a general and fully relativistic pulsar timing formula.

  13. Results on diamond timing detector for the TOTEM experiment

    NASA Astrophysics Data System (ADS)

    Bossini, E.

    2016-07-01

    We describe the results and status of our R&D on diamond timing detectors for the TOTEM experiment at CERN. Tests with commercial devices have been done and here reported; the unsatisfactory results push us to design a new detector. We present test beams results and the front-end electronics, critical point of the design. Efficiency studies and timing performance dependence from detector capacitance will be also reported.

  14. The lead time tradeoff: the case of health states better than dead.

    PubMed

    Pinto-Prades, José Luis; Rodríguez-Míguez, Eva

    2015-04-01

    Lead time tradeoff (L-TTO) is a variant of the time tradeoff (TTO). L-TTO introduces a lead period in full health before illness onset, avoiding the need to use 2 different procedures for states better and worse than dead. To estimate utilities, additive separability is assumed. We tested to what extent violations of this assumption can bias utilities estimated with L-TTO. A sample of 500 members of the Spanish general population evaluated 24 health states, using face-to-face interviews. A total of 188 subjects were interviewed with L-TTO and the rest with TTO. Both samples evaluated the same set of 24 health states, divided into 4 groups with 6 health states per set. Each subject evaluated 1 of the sets. A random effects regression model was fitted to our data. Only health states better than dead were included in the regression since it is in this subset where additive separability can be tested clearly. Utilities were higher in L-TTO in relation to TTO (on average L-TTO adds about 0.2 points to the utility of health states), suggesting that additive separability is violated. The difference between methods increased with the severity of the health state. Thus, L-TTO adds about 0.14 points to the average utility of the less severe states, 0.23 to the intermediate states, and 0.28 points to the more severe estates. L-TTO produced higher utilities than TTO. Health problems are perceived as less severe if a lead period in full health is added upfront, implying that there are interactions between disjointed time periods. The advantages of this method have to be compared with the cost of modeling the interaction between periods. © The Author(s) 2014.

  15. Two-degree-of-freedom fractional order-PID controllers design for fractional order processes with dead-time.

    PubMed

    Li, Mingjie; Zhou, Ping; Zhao, Zhicheng; Zhang, Jinggang

    2016-03-01

    Recently, fractional order (FO) processes with dead-time have attracted more and more attention of many researchers in control field, but FO-PID controllers design techniques available for the FO processes with dead-time suffer from lack of direct systematic approaches. In this paper, a simple design and parameters tuning approach of two-degree-of-freedom (2-DOF) FO-PID controller based on internal model control (IMC) is proposed for FO processes with dead-time, conventional one-degree-of-freedom control exhibited the shortcoming of coupling of robustness and dynamic response performance. 2-DOF control can overcome the above weakness which means it realizes decoupling of robustness and dynamic performance from each other. The adjustable parameter η2 of FO-PID controller is directly related to the robustness of closed-loop system, and the analytical expression is given between the maximum sensitivity specification Ms and parameters η2. In addition, according to the dynamic performance requirement of the practical system, the parameters η1 can also be selected easily. By approximating the dead-time term of the process model with the first-order Padé or Taylor series, the expressions for 2-DOF FO-PID controller parameters are derived for three classes of FO processes with dead-time. Moreover, compared with other methods, the proposed method is simple and easy to implement. Finally, the simulation results are given to illustrate the effectiveness of this method.

  16. A PI tuning rule for integrating plus dead time processes with parametric uncertainty.

    PubMed

    Mercader, Pedro; Baños, Alfonso

    2017-03-01

    A novel method to tune a Proportional-Integral (PI) compensator for an integrating plus dead time (IPDT) process, in presence of interval parametric uncertainty, is presented. The design is based on optimization of load disturbance rejection with constraints on the magnitude of the sensitivity and complementary sensitivity functions, that must be satisfied for any element belonging to a set of plants. Instead of solving this problem with a brute force approach (grid the uncertainty set), we prove that this problem can be solved by considering only two plants. That lets us to obtain a tuning rule, after using some approximations. To conclude, some examples will be given in order to elucidate the usefulness of the proposed tuning rule.

  17. Discrimination of shot-noise-driven Poisson processes by external dead time - Application of radioluminescence from glass

    NASA Technical Reports Server (NTRS)

    Saleh, B. E. A.; Tavolacci, J. T.; Teich, M. C.

    1981-01-01

    Ways in which dead time can be used to constructively enhance or diminish the effects of point processes that display bunching in the shot-noise-driven doubly stochastic Poisson point process (SNDP) are discussed. Interrelations between photocount bunching arising in the SNDP and the antibunching character arising from dead-time effects are investigated. It is demonstrated that the dead-time-modified count mean and variance for an arbitrary doubly stochastic Poisson point process can be obtained from the Laplace transform of the single-fold and joint-moment-generating functions for the driving rate process. The theory is in good agreement with experimental values for radioluminescence radiation in fused silica, quartz, and glass, and the process has many applications in pulse, particle, and photon detection.

  18. Design and analysis of modified Smith predictors for self-regulating and non-self regulating processes with dead time

    NASA Astrophysics Data System (ADS)

    Saravanakumar, G.; Wahidabanu, R. S. D.; Nayak, C. G.

    2007-08-01

    A modification of Smith predictor for controlling the higher order processes with integral action ad long dead-time is proposed in this paper. The controller used in this Smith predictor is an Integral-Proportional Derivative controller, where the Integrator is in the forward path and the Proportional and Derivative control are in the feedback, acting on the feedback signal. The main objective of this paper is to design a Dead Time Compensator(DTC), which has minimum tuning parameters, simple controller tuning, robust performance of tuning formulae and to obtain a critically damped system which is as fast as possible in its setpoint and load disturbance rejection performance. The controller in this paper is tuned by an adaptive method. This paper also presents a survey of various dead time compensators and their performance analysis.

  19. Monte Carlo analysis of the influence of germanium dead layer thickness on the HPGe gamma detector experimental efficiency measured by use of extended sources.

    PubMed

    Chham, E; García, F Piñero; El Bardouni, T; Ferro-García, M Angeles; Azahra, M; Benaalilou, K; Krikiz, M; Elyaakoubi, H; El Bakkali, J; Kaddour, M

    2014-09-22

    We have carried out a study to figure out the influence of crystal inactive-layer thickness on gamma spectra measured by an HPGe detector. The thickness of this dead layer (DL) is not known (no information about it was delivered by the manufacturer) due to the existence of a transition zone where photons are increasingly absorbed. To perform this analyses a virtual model of a Canberra HPGe detector was produced with the aid of MCNPX 2.7 code. The main objective of this work is to produce an optimal modeling for our GPGe detector. To this end, the study included the analysis of the total inactive germanium layer thickness and the active volume that are needed in order to obtain the smallest discrepancy between calculated and experimental efficiencies. Calculations and measurements were performed for all of the radionuclides included in a standard calibration gamma cocktail solution. Different geometry sources were used: a Marinelli and two other new sources represented as S(1) and S(2). The former was used for the determination of the active volume, whereas the two latter were used for the determination of the face and lateral DL, respectively. The model was validated by comparing calculated and experimental full energy peak efficiencies in the 50-1900keV energy range. the results show that the insertion of the DL parameter in the modeling is absolutely essential to reproduce the experimental results, and that the thickness of this DL varies from one position to the other on the detector surface.

  20. 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.

  1. Optimizing timing performance of CdTe detectors for PET

    NASA Astrophysics Data System (ADS)

    Nakhostin, M.

    2017-10-01

    Despite several attractive properties, the poor timing performance of compound semiconductor detectors such as CdTe and CdZnTe has hindered their use in commercial PET imaging systems. The standard method of pulse timing with such detectors is to employ a constant-fraction discriminator at the output of a timing filter which is fed by the pulses from a charge-sensitive preamplifier. The method has led to a time resolution of about 10 ns at full-width at half-maximum (FWHM) with 1 mm thick CdTe detectors. This paper presents a detailed investigation on the parameters limiting the timing performance of Ohmic contact planar CdTe detectors with the standard pulse timing method. The jitter and time-walk errors are studied through simulation and experimental measurements and it is revealed that the best timing results obtained with the standard timing method suffer from a significant loss of coincidence events (~50%). In order to improve the performance of the detectors with full detection efficiency, a new digital pulse timing method based on a simple pattern recognition technique was developed. A time resolution of 3.29  ±  0.10 ns (FWHM) in the energy range of 300–650 keV was achieved with an Ohmic contact planar CdTe detector (5  ×  5  ×  1 mm3). The digital pulse processing method was also used to correct for the charge-trapping effect and an improvement in the energy resolution from 4.83  ±  0.66% to 2.780  ±  0.002% (FWHM) at 511 keV was achieved. Further improvement of time resolution through a moderate cooling of the detector and the application of the method to other detector structures are also discussed.

  2. R&D on a new type of micropattern gaseous detector: The Fast Timing Micropattern detector

    NASA Astrophysics Data System (ADS)

    Abbaneo, D.; Abbas, M.; Abbrescia, M.; Akl, M. Abi; Aboamer, O.; Acosta, D.; Ahmad, A.; Ahmed, W.; Aleksandrov, A.; Altieri, P.; Asawatangtrakuldee, C.; Aspell, P.; Assran, Y.; Awan, I.; Bally, S.; Ban, Y.; Banerjee, S.; Barashko, V.; Barria, P.; Bencze, G.; Beni, N.; Benussi, L.; Bhopatkar, V.; Bianco, S.; Bos, J.; Bouhali, O.; Braghieri, A.; Braibant, S.; Buontempo, S.; Calabria, C.; Caponero, M.; Caputo, C.; Cassese, F.; Castaneda, A.; Cauwenbergh, S.; Cavallo, F. R.; Celik, A.; Choi, M.; Choi, S.; Christiansen, J.; Cimmino, A.; Colafranceschi, S.; Colaleo, A.; Garcia, A. Conde; Czellar, S.; Dabrowski, M. M.; Lentdecker, G. De; Oliveira, R. De; Robertis, G. de; Dildick, S.; Dorney, B.; Endroczi, G.; Errico, F.; Fallavollita, F.; Fenyvesi, A.; Ferry, S.; Furic, I.; Giacomelli, P.; Gilmore, J.; Golovtsov, V.; Guiducci, L.; Guilloux, F.; Gutierrez, A.; Hadjiiska, R. M.; Hauser, J.; Hoepfner, K.; Hohlmann, M.; Hoorani, H.; Iaydjiev, P.; Jeng, Y. G.; Kamon, T.; Karchin, P.; Korytov, A.; Krutelyov, S.; Kumar, A.; Kim, H.; Lee, J.; Lenzi, T.; Litov, L.; Loddo, F.; Madorsky, A.; Maerschalk, T.; Maggi, M.; Magnani, A.; Mal, P. K.; Mandal, K.; Marchioro, A.; Marinov, A.; Majumdar, N.; Merlin, J. A.; Mitselmakher, G.; Mohanty, A. K.; Mohapatra, A.; Molnar, J.; Muhammad, S.; Mukhopadhyay, S.; Naimuddin, M.; Nuzzo, S.; Oliveri, E.; Pant, L. M.; Paolucci, P.; Park, I.; Passeggio, G.; Pavlov, B.; Philipps, B.; Piccolo, D.; Postema, H.; Baranac, A. Puig; Radi, A.; Radogna, R.; Raffone, G.; Ranieri, A.; Rashevski, G.; Ressegotti, M.; Riccardi, C.; Rodozov, M.; Rodrigues, A.; Ropelewski, L.; RoyChowdhury, S.; Ryu, G.; Ryu, M. S.; Safonov, A.; Salva, S.; Saviano, G.; Sharma, A.; Sharma, A.; Sharma, R.; Shah, A. H.; Shopova, M.; Sturdy, J.; Sultanov, G.; Swain, S. K.; Szillasi, Z.; Talvitie, J.; Tatarinov, A.; Tuuva, T.; Tytgat, M.; Vai, I.; Stenis, M. Van; Venditti, R.; Verhagen, E.; Verwilligen, P.; Vitulo, P.; Volkov, S.; Vorobyev, A.; Wang, D.; Wang, M.; Yang, U.; Yang, Y.; Yonamine, R.; Zaganidis, N.; Zenoni, F.; Zhang, A.

    2017-02-01

    This contribution introduces a new type of Micropattern Gaseous Detector, the Fast Timing Micropattern (FTM) detector, utilizing fully Resistive WELL structures. The structure of the prototype will be described in detail and the results of the characterization study performed with an X-ray gun will be presented, together with the first results on time resolution based on data collected with muon/pion test beams.

  3. High-speed detector for time-resolved diffraction studies

    PubMed Central

    Singh, Bipin; Miller, Stuart R.; Bhandari, Harish B.; Graceffa, Rita; Irving, Thomas C.; Nagarkar, Vivek V.

    2013-01-01

    There are a growing number of high brightness synchrotron sources that require high-frame-rate detectors to provide the time-scales required for performing time-resolved diffraction experiments. We report on the development of a very high frame rate CMOS X-ray detector for time-resolved muscle diffraction and time-resolved solution scattering experiments. The detector is based on a low-afterglow scintillator, provides a megapixel resolution with frame rates of up to 120,000 frames per second, an effective pixel size of 64 µm, and can be adapted for various X-ray energies. The paper describes the detector design and initial results of time-resolved diffraction experiments on a synchrotron beamline. PMID:24489595

  4. Alternating iterative regression method for dead time estimation from experimental designs.

    PubMed

    Pous-Torres, S; Torres-Lapasió, J R; Baeza-Baeza, J J; García-Alvarez-Coque, M C

    2009-05-01

    An indirect method for dead time (t (0)) estimation in reversed-phase liquid chromatography, based on a relationship between retention time and organic solvent content, is proposed. The method processes the retention data obtained in experimental designs. In order to get more general validity and enhance the accuracy, the information from several compounds is used altogether in an alternating regression fashion. The method was applied to nitrosamines, alkylbenzenes, phenols, benzene derivatives, polycyclic aromatic hydrocarbons and beta-blockers, among other compounds, chromatographed in a cyano and several C18 columns. A comprehensive validation was carried out by comparing the results with those provided by the injection of markers, the observation of the solvent front and the homologous series method. It was also found that different groups of compounds yielded the same t (0) value with the same column, which was verified in different solvent composition windows. The method allows improved models useful for optimisation or for other purposes, since t (0) can be estimated with the retention data of the target solutes.

  5. Afterpulse time spectra of high-speed photon detectors

    NASA Astrophysics Data System (ADS)

    Leskovar, B.

    1985-01-01

    Recent progress of understanding of the afterpulse time spectra of high-speed photon detectors using photoemission and secondary emission processes is reviewed and summarized. Furthermore, the afterpulse time spectra of high-gain conventionally designed and microchannel plate photon detectors was investigated. Specifically, the devices studied included RCA 8850, RCA 8854 and ITT F 4129g photomultipliers. Descriptions are given of the measuring techniques.

  6. Fast Timing Detector R&D for Forward Proton Detectors at LHC

    NASA Astrophysics Data System (ADS)

    Snyder, Christina

    2017-01-01

    Quartz Timing Cherenkov (QUARTIC) detectors were tested at Fermilab Test Beam Facility in order to determine the timing resolution of very forward protons from collisions at the Large Hadron Collider (LHC). The active media of the detectors are quartz and sapphire, which are radiation hard and high light-yield materials. These detectors are constructed of 20 L-shaped bars that enable one to differentiate and detect more than one proton from the same LHC bunch crossing. The QUARTIC detectors have a small active area of 4cm2, which is well-matched to the acceptance of the scattered protons. Our experimental results will be presented and further testing of this design is planned.

  7. Determination of time zero from a charged particle detector

    DOEpatents

    Green, Jesse Andrew [Los Alamos, NM

    2011-03-15

    A method, system and computer program is used to determine a linear track having a good fit to a most likely or expected path of charged particle passing through a charged particle detector having a plurality of drift cells. Hit signals from the charged particle detector are associated with a particular charged particle track. An initial estimate of time zero is made from these hit signals and linear tracks are then fit to drift radii for each particular time-zero estimate. The linear track having the best fit is then searched and selected and errors in fit and tracking parameters computed. The use of large and expensive fast detectors needed to time zero in the charged particle detectors can be avoided by adopting this method and system.

  8. Radium mass balance in the Dead Sea - time scale and quantification of circulation in the aquifer

    NASA Astrophysics Data System (ADS)

    Kiro, Y.; Weinstein, Y.; Starinsky, A.; Yechieli, Y.

    2013-12-01

    The Dead Sea hypersaline water and the adjacent groundwater are highly enriched in radium, whose concentration is 2-3 orders of magnitude higher than in the ocean. The combination of carbonate rocks, from which radium is extracted, and the high solubility of radium in hypersaline water contribute these high activities, especially of 226Ra. Being a terminal lake, the Dead Sea concentrates radium mainly the long-lived (t1/2=1600 y) 226Ra isotope, from the surrounding water and groundwater sources. Due to the differences in the isotope half-lives, the shorter-lived isotopes (228Ra, 224Ra and 223Ra) are enriched in the groundwater compared with the lake while 226Ra is enriched both in the lake water (~145 dpm/L) and in the groundwater (up to 500 dpm/L). The 228Ra/226Ra activity ratio in the groundwater on the western shore of the Dead Sea is significantly low (0.03-0.05), representing the high U/Th ratio in the carbonate rocks and sediments around the Dead Sea. However, the high 222Rn activities (up to 60,000 dpm/L) in the groundwater could not be explained by the U content of the carbonate rocks and probably indicate mobility of 226Ra along flow paths where salinity or temperature changes. During Dead Sea water circulation in the aquifer 226Ra is removed from the water by barite precipitation, while 228Ra is added to the water due to recoil from the aquifer sediments. The buildup rate of 228Ra in the circulated Dead Sea water was used for quantifying the circulation rate and the age of the groundwater, while the mass balances of both 228Ra and 226Ra in the lake were used for the quantification of the circulation volume. The rate of Dead Sea water inflow into the aquifer was found to be a few m/y and the annual volume of Dead Sea water circulating in the aquifer is ~320 m3/y. The opposite behavior of 226Ra and 228Ra during the circulation constrains the error on the calculated velocity to be relatively low (ς=×20) and allows the estimation of other sources and sinks

  9. The diamond time of flight detector of the TOTEM experiment

    NASA Astrophysics Data System (ADS)

    Berretti, Mirko

    2017-02-01

    This contribution describes the design and the performance of a novel timing detector developed by the TOTEM Collaboration. The detector will be installed inside the TOTEM Roman Pots (RPs) and will measure the Time-Of-Flight (TOF) of the protons produced in the central diffractive (CD) interactions at the LHC. In particular, the measurement of the proton TOF allows the determination of the vertex longitudinal position where the protons are produced, thus allowing the protons association with one of the vertices reconstructed by the CMS detectors. The TOF detector is based on single crystal CVD (scCVD) diamond plates and it is designed in order to measure the protons TOF with 50 ps time resolution. To achieve this performance, a dedicated fast and low noise electronics for the signal amplification has been developed. Indeed, while diamond sensors have lower noise and faster signals than silicon sensors, the amount of charge released in the medium is lower. The digitization of the diamond signal is performed sampling the waveform at 10 GSa/s with the SAMPIC chip. The performance of the first TOF detector installed in the LHC in November 2015 will be reported. An overview of the clock distribution system and of the control system which interfaces the timing detectors to the experiment DAQ is finally given.

  10. Multi-channel picosecond photon timing with microchannel plate detectors

    NASA Astrophysics Data System (ADS)

    Lapington, J. S.; Conneely, T.

    2011-08-01

    Microchannel plate-based detectors have the capability to photon-count at time resolutions which outperform solid-state devices such as the APD or SiPM, and have a geometry that lends itself to pixelated readouts. We describe a multi-channel, photon-counting microchannel plate detector optimised for photon timing in the picosecond regime. The detector was originally developed for application to time-resolved spectroscopy in the life sciences, however its performance characteristics make it suitable for applications where high time resolution and multi-channel photon-counting are required including Cherenkov light detection in nuclear physics, particle physics, and astroparticle astronomy.We describe the prototype detector, a sealed tube device comprising an optical photocathode proximity focussed to a small pore microchannel plate stack. Event charge is collected on a multi-channel readout comprising an 8×8 pixel array, manufactured on a multilayer ceramic, which provides vacuum integrity for the detector enclosure and a multi-way electrical feedthrough for the readout array. Each pixel addresses one channel of a NINO ASIC, a multi-channel preamplifier-discriminator device. The discriminator outputs are timed to 25 ps by the HPTDC time-to-digital converter ASIC, which uses a time-over-threshold technique for amplitude walk correction. We present performance measurements using a pulsed laser of the 64 channel prototype system comprising a 25 mm detector, NINO front-end, and a CAEN V1290A VME module utilising HPTDC. We discuss the next phase in the project—design and manufacture of a 40 mm detector with a 16×16 pixel2 readout coupled to custom NINO/HPTDC electronics constructed as a series of 64 channel modules, expandable to even larger channel densities.

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

    PubMed

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

    2008-10-01

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

  12. Inorganic scintillator detectors for real-time verification during brachytherapy

    NASA Astrophysics Data System (ADS)

    Kertzscher, G.; Beddar, S.

    2017-05-01

    Widespread use of real-time dose measurement technology to verify brachytherapy (BT) treatments is currently limited because only few detectors exhibit the large dynamic range and signal intensities that is required to accurately report the data. Inorganic scintillator detectors (ISDs) are promising for real-time BT verification because they can exhibit large signal intensities. Luminescence properties of ISDs based on ruby, Y2O3:Eu and CsI:Tl were compared with BCF-60 plastic scintillators to determine their potential for BT verification. Measurements revealed that ISDs can exhibit signal intensities 1800 times larger than BCF-60 and that the Čerenkov and fluorescence light contamination is negligible. The favourable luminescence properties of ISDs opens the possibility to manufacture simplified detector systems that can lead to more widespread real-time verification during BT treatment deliveries.

  13. A new timing detector for the CT-PPS project

    NASA Astrophysics Data System (ADS)

    Arcidiacono, R.

    2017-02-01

    The CT-PPS detector will be installed close to the beam line on both sides of CMS, 200 m downstream the interaction point. This detector will measure forward scattered protons, allowing detailed studies of diffractive hadron physics and Central Exclusive Production. The main components of the CT-PPS detector are a silicon tracking system and a timing system. In this contribution we present the proposal of an innovative solution for the timing system, based on Ultra-Fast Silicon Detectors (UFSD). UFSD are a novel concept of silicon detectors potentially able to obtain the necessary time resolution (∼20 ps on the proton arrival time). The use of UFSD has also other attractive features as its material budget is small and the pixel geometries can be tailored to the precise physics distribution of protons. UFSD prototypes for CT-PPS have been designed by CNM (Barcelona) and FBK (Trento): we will present the status of the sensor productions and of the low-noise front-end electronics currently under development and test.

  14. The Feynman-Y Statistic in Relation to Shift-Register Neutron Coincidence Counting: Precision and Dead Time

    SciTech Connect

    Croft, Stephen; Santi, Peter A.; Henzlova, Daniela; Hauck, Danielle K.; Favalli, Andrea

    2012-07-13

    The Feynman-Y statistic is a type of autocorrelation analysis. It is defined as the excess variance-to-mean ratio, Y = VMR - 1, of the number count distribution formed by sampling a pulse train using a series of non-overlapping gates. It is a measure of the degree of correlation present on the pulse train with Y = 0 for Poisson data. In the context of neutron coincidence counting we show that the same information can be obtained from the accidentals histogram acquired using the multiplicity shift-register method, which is currently the common autocorrelation technique applied in nuclear safeguards. In the case of multiplicity shift register analysis however, overlapping gates, either triggered by the incoming pulse stream or by a periodic clock, are used. The overlap introduces additional covariance but does not alter the expectation values. In this paper we discuss, for a particular data set, the relative merit of the Feynman and shift-register methods in terms of both precision and dead time correction. Traditionally the Feynman approach is applied with a relatively long gate width compared to the dieaway time. The main reason for this is so that the gate utilization factor can be taken as unity rather than being treated as a system parameter to be determined at characterization/calibration. But because the random trigger interval gate utilization factor is slow to saturate this procedure requires a gate width many times the effective 1/e dieaway time. In the traditional approach this limits the number of gates that can be fitted into a given assay duration. We empirically show that much shorter gates, similar in width to those used in traditional shift register analysis can be used. Because the way in which the correlated information present on the pulse train is extracted is different for the moments based method of Feynman and the various shift register based approaches, the dead time losses are manifested differently for these two approaches. The resulting

  15. Detection of viable and dead Listeria monocytogenes on gouda-like cheeses by real-time PCR.

    PubMed

    Rudi, K; Naterstad, K; Drømtorp, S M; Holo, H

    2005-01-01

    Surface contamination by Listeria monocytogenes of gouda-like cheeses during processing represents a potential public health problem. The aim of this work was to develop novel real-time PCR diagnostics to detect the presence of viable, dead or viable but not culturable (VBNC) cells on gouda-like cheeses. We used ethidium monoazide bromide (EMA)-PCR for direct quantification of viable and dead cells, while semiquantitative detection of culturable cells below the PCR detection limit (c. 100 CFU g(-1)) was obtained by combining growth and real-time PCR. We were able to quantify the fraction of >0.5% viable cells in a background of dead cells by EMA-PCR, given that the viable cell concentration was above the PCR detection limit. The combined growth and real-time PCR complemented the EMA-PCR, and enabled semiquantitative detection of low levels of culturable cells (10 and 100 CFU g(-1)). The significance of this work is that we have developed a novel concept for detection of viable and potentially infectious L. monocytogenes.

  16. Ultrafast charge division imaging detector

    NASA Astrophysics Data System (ADS)

    Liu, Alan; Woo, Brian; Odom, Robert W.

    2000-11-01

    We have developed position computing electronics having less than 60 ns dead times for resistive anode encoders, a form of charge division imaging detector. These electronics are at least a factor of 5 faster than anything available commercially and are based on using a fast, self-resetting charge integrator and subrange digital division techniques. Our primary application for this detector is secondary ion mass spectrometry (SIMS)/ions imaging and we demonstrate that SIMS imaging applications using these ultrafast electronics can readily be performed at ion intensities above 106 cps. This article discusses the overall electronics design and presents experimental data on dead-time measurements, detector lateral resolution, and SIMS imaging.

  17. Detectors and Concepts for sub-100 ps timing with gaseous detectors

    NASA Astrophysics Data System (ADS)

    González-Díaz, D.; Palomo, F. R.; González, J.; Chen, H.

    2017-03-01

    We give a short compendium of the main ongoing detectors and concepts capable of performing accurate sub-100 ps timing at high particle fluxes and on large areas, through technologies based on gaseous media. We briefly discuss the state-of-the-art, technological limitations and prospects, and a new bizarre idea.

  18. Quantum detector tomography of a time-multiplexed superconducting nanowire single-photon detector at telecom wavelengths.

    PubMed

    Natarajan, Chandra M; Zhang, Lijian; Coldenstrodt-Ronge, Hendrik; Donati, Gaia; Dorenbos, Sander N; Zwiller, Val; Walmsley, Ian A; Hadfield, Robert H

    2013-01-14

    Superconducting nanowire single-photon detectors (SNSPDs) are widely used in telecom wavelength optical quantum information science applications. Quantum detector tomography allows the positive-operator-valued measure (POVM) of a single-photon detector to be determined. We use an all-fiber telecom wavelength detector tomography test bed to measure detector characteristics with respect to photon flux and polarization, and hence determine the POVM. We study the SNSPD both as a binary detector and in an 8-bin, fiber based, Time-Multiplexed (TM) configuration at repetition rates up to 4 MHz. The corresponding POVMs provide an accurate picture of the photon number resolving capability of the TM-SNSPD.

  19. Detection and Real Time Spectroscopy of Charged Particles with the TimePix Pixel Detector

    NASA Astrophysics Data System (ADS)

    Granja, Carlos; Jakubek, Jan; Platkevic, Michal; Pospisil, Stanislav; Vykydal, Zdenek

    2010-01-01

    We tested the position—, spectral— and time—resolution capability of the TimePix semiconductor detector together with the USB readout interface and Pixelman control and DAQ software tool for detection and visualization of particles. Event—by—event spectroscopy can be achieved by real time analysis of the characteristic tracks and specific response of different radiation in the pixel detector.

  20. Time projection chambers for the T2K near detectors

    NASA Astrophysics Data System (ADS)

    Abgrall, N.; Andrieu, B.; Baron, P.; Bene, P.; Berardi, V.; Beucher, J.; Birney, P.; Blaszczyk, F.; Blondel, A.; Bojechko, C.; Boyer, M.; Cadoux, F.; Calvet, D.; Catanesi, M. G.; Cervera, A.; Colas, P.; De La Broise, X.; Delagnes, E.; Delbart, A.; Di Marco, M.; Druillole, F.; Dumarchez, J.; Emery, S.; Escudero, L.; Faszer, W.; Ferrere, D.; Ferrero, A.; Fransham, K.; Gaudin, A.; Giganti, C.; Giomataris, I.; Giraud, J.; Goyette, M.; Hamano, K.; Hearty, C.; Henderson, R.; Herlant, S.; Ieva, M.; Jamieson, B.; Jover-Mañas, G.; Karlen, D.; Kato, I.; Konaka, A.; Laihem, K.; Langstaff, R.; Laveder, M.; Le Coguie, A.; Le Dortz, O.; Le Ross, M.; Lenckowski, M.; Lux, T.; Macaire, M.; Mahn, K.; Masciocchi, F.; Mazzucato, E.; Mezzetto, M.; Miller, A.; Mols, J.-Ph.; Monfregola, L.; Monmarthe, E.; Myslik, J.; Nizery, F.; Openshaw, R.; Perrin, E.; Pierre, F.; Pierrepont, D.; Poffenberger, P.; Popov, B.; Radicioni, E.; Ravonel, M.; Reymond, J.-M.; Ritou, J.-L.; Roney, M.; Roth, S.; Sánchez, F.; Sarrat, A.; Schroeter, R.; Stahl, A.; Stamoulis, P.; Steinmann, J.; Terhorst, D.; Terront, D.; Tvaskis, V.; Usseglio, M.; Vallereau, A.; Vasseur, G.; Wendland, J.; Wikström, G.; Zito, M.

    2011-05-01

    The T2K experiment is designed to study neutrino oscillation properties by directing a high intensity neutrino beam produced at J-PARC in Tokai, Japan, towards the large Super-Kamiokande detector located 295 km away, in Kamioka, Japan. The experiment includes a sophisticated near detector complex, 280 m downstream of the neutrino production target in order to measure the properties of the neutrino beam and to better understand neutrino interactions at the energy scale below a few GeV. A key element of the near detectors is the ND280 tracker, consisting of two active scintillator-bar target systems surrounded by three large time projection chambers (TPCs) for charged particle tracking. The data collected with the tracker are used to study charged current neutrino interaction rates and kinematics prior to oscillation, in order to reduce uncertainties in the oscillation measurements by the far detector. The tracker is surrounded by the former UA1/NOMAD dipole magnet and the TPCs measure the charges, momenta, and particle types of charged particles passing through them. Novel features of the TPC design include its rectangular box layout constructed from composite panels, the use of bulk micromegas detectors for gas amplification, electronics readout based on a new ASIC, and a photoelectron calibration system. This paper describes the design and construction of the TPCs, the micromegas modules, the readout electronics, the gas handling system, and shows the performance of the TPCs as deduced from measurements with particle beams, cosmic rays, and the calibration system.

  1. Neutron Bang Time Detector Based on a Light Pipe

    SciTech Connect

    Glebov, V Y; Moran, M; Stoeckl, C; Sangster, T C; Cruz, M

    2008-05-08

    A neutron bang time detector consisting of a scintillator, light pipe, photomultiplier tube (PMT), and high-bandwidth oscilloscope has been implemented on the 60-beam, 30-kJ OMEGA Laser Facility at the University of Rochester's Laboratory for Laser Energetics. Light from the scintillator, located 23 cm from the target, is transmitted outside the target bay through a 9.6-m-long, 2-in.-diam polished stainless steel pipe to the PMT. The PMT signal is recorded by two channels of a 6-GHz, 10-GS/s Tektronix 6604 oscilloscope. The OMEGA optical fiducial pulse train is recorded on the third oscilloscope channel using a fast photodiode to provide the timing reference to the laser. The bang-time detector is absolutely calibrated in time and is able to measure bang time for neutron yields above 1 x 10{sup 9} with accuracy of better than 25 ps.

  2. Characterization of a Precision Pulsar Timing Gravitational Wave Detector

    NASA Astrophysics Data System (ADS)

    Lam, Michael T.

    2017-01-01

    We aim to construct a Galactic-scale detector comprised of an array of pulsars distributed across the sky in an effort to detect low-frequency (nanohertz) gravitational waves. Even without a detection, observations of pulsar timing arrays have allowed us to begin to place impactful astrophysical constraints on dynamical processes occurring during galaxy mergers. Understanding the detector is necessary for improving our sensitivity to gravitational waves and making a detection. Therefore, our goal is to characterize the entire propagation path through the pulsar timing array detector. To do so, we must understand: what intrinsic noise processes occur at the pulsar, what effects the interstellar medium has on pulsed radio emission, and what errors we introduce when measuring the incident electromagnetic radiation at our observatories.In this work, we observed of one of the most spin-stable objects known for 24 hours to understand the fundamental limits of precision pulsar timing. We investigated the effect of non-simultaneous, multi-frequency sampling of pulsar dispersion measures on timing and analyzed the cause of deterministic and stochastic temporal variations seen in dispersion measure time series. We analyzed errors in pulse arrival times and determined the white noise budget for pulsars on the timescale of a single observation. Finally, we measured the excess noise beyond the white noise model in pulsar timing residuals and incorporated our results into a global model over all pulsar populations to improve excess noise scaling relations.

  3. Neutron Bang Time Detector Based on a Light Pipe

    SciTech Connect

    Glebov, V.Yu.; Moran, M.; Stoeckl, C.; Sangster, T.C.; Cruz, M.

    2008-11-13

    A neutron bang time detector consisting of a scintillator, light pipe, photomultiplier tube (PMT), and high-bandwidth oscilloscope has been implemented on the 60-beam, 30 kJ OMEGA Laser Facility at the University of Rochester’s Laboratory for Laser Energetics. Light from the scintillator, located 23 cm from the target, is transmitted from the target bay through a 9.6-m-long, 2 in. diameter polished stainless steel pipe to the PMT. The PMT signal is recorded by two channels of a 6 GHz, 10 GS/ s Tektronix 6604 oscilloscope. The OMEGA optical fiducial pulse train is recorded on the third oscilloscope channel using a fast photodiode to provide the timing reference to the laser. This bang time detector is absolutely temporally calibrated and has been demonstrated to measure the bang time for neutron yields above 1 x 10^9 with an accuracy of better than 25 ps.

  4. Neutron bang time detector based on a light pipe

    SciTech Connect

    Glebov, V. Yu.; Stoeckl, C.; Sangster, T. C.; Cruz, M.; Moran, M.

    2008-10-15

    A neutron bang time detector consisting of a scintillator, light pipe, photomultiplier tube (PMT), and high-bandwidth oscilloscope has been implemented on the 60-beam, 30 kJ OMEGA Laser Facility at the University of Rochester's Laboratory for Laser Energetics. Light from the scintillator, located 23 cm from the target, is transmitted from the target bay through a 9.6-m-long, 2 in. diameter polished stainless steel pipe to the PMT. The PMT signal is recorded by two channels of a 6 GHz, 10 GS/s Tektronix 6604 oscilloscope. The OMEGA optical fiducial pulse train is recorded on the third oscilloscope channel using a fast photodiode to provide the timing reference to the laser. This bang time detector is absolutely temporally calibrated and has been demonstrated to measure the bang time for neutron yields above 1x10{sup 9} with an accuracy of better than 25 ps.

  5. The timing upgrade project of the TOTEM Roman Pots detectors

    NASA Astrophysics Data System (ADS)

    Berretti, M.

    2016-07-01

    We describe the upgrade project developed by the TOTEM Collaboration to measure the time of flight (TOF) of the protons in the vertical Roman Pot detectors. The physics program that the upgraded system aims to accomplish will be addressed. Simulation studies allowed us to define a geometry of the sensor such that the detection inefficiency due to the pile-up of the particles in the same electrode is low even with a small amount of read-out channels. The measurement of the protons TOF with 50 ps time resolution requires the development of several challenging technological solutions. The arrival time of the protons will be measured by scCVD diamond detectors, for which a dedicated fast and low-noise electronics for the signal amplification has been designed. Indeed, while diamond sensors have the advantage of higher radiation hardness, lower noise and faster signal than silicon sensors, the amount of charge released in the medium is lower. The sampling of the waveform is performed at a rate up to 10 GS/s with the SAMPIC chip. The sampled waveforms are then analysed offline where optimal algorithms can be implemented to reduce the time walk effects. The clock distribution system, based on the Universal Picosecond Timing System developed at GSI, is optimized in order to have a negligible uncertainty on the TOF measurement. Finally an overview of the control system which will interface the timing detectors to the experiment DAQ is given.

  6. Timing Measurements of Scintillator Bars with Silicon Phtotomultiplier Light Detectors

    NASA Astrophysics Data System (ADS)

    Shelor, Mark; Elizondo, Leonardo; Ritt, Stefan

    2016-03-01

    To track and analyze cosmic rays via precise measurements of muon and similarly penetrating particle's airshower axes directions, we constructed a prototype consisting of two 1-meter long scintillator bars. Each bar is embedded with green wavelength shifting fibers to increase detection rate of two silicon photomultiplier, SiPM, light detectors to record light produced by cosmic rays via scintillation. The focus of the experiment was to determine the performance of these devices. Evaluation was performed for two makes of SiPM models - from AdvanSiD and Hamamatsu. Timing measurements of the apparatus were performed under several trigger conditions to filter out noise such as coincidence trigger with 2 photomultiplier detectors, as well as SiPM detectors in self-triggered mode. The SiPM detector waveforms were digitized using a 4-channel fast waveform sampler, the DRS4 digitizer. Signals were analyzed with the CERN PAW package. From our results, we deduced the speed of light in the scintillator using the SiPM modules to be about 66% of the speed of light in a vacuum which is in accordance with the specifications of the index of refraction for the fibers given by the manufacturer's specifications. The results of our timing measurements would be presented. Dept. of Ed. Title V Grant PO31S090007.

  7. Highly parallel SPAD detector for time-resolved lab-on-chip

    NASA Astrophysics Data System (ADS)

    Benetti, Michele; Iori, Daniele; Pancheri, Lucio; Borghetti, Fausto; Pasquardini, Laura; Lunelli, Lorenzo; Pederzolli, Cecilia; Gonzo, Lorenzo; Dalla Betta, Gian-Franco; Stoppa, David

    2010-05-01

    Fluorescence lifetime detection is widely used in molecular biology to monitor many cell parameters (such as pH, ion concentrations, etc.) and for an early diagnosis of many pathologies. In a typical fluorescence lifetime experiment a pulsed laser is used to excite the fluorescent dyes and the emitted light is revealed by means of high sensitivity detectors, typically: intensified CCD, PMTs or Single-Photon Avalanche Diodes (SPADs).In this contribute we present a SPAD detector module fabricated in a 0.35μm High Voltage CMOS technology to be used within a lab-on-chip system consisting of a micro-reactor array for bioaffinity assays based on fluorescence markers. The detector module, having a total area of 600 x 900 μm2, can be arranged to build a small pixel array to be directly coupled to the micro-reactors. No emission filters are needed, since the ultra-short laser pulse is cut off in the time domain. The module consists of a 10x10-SPAD array, where each SPAD cell is equipped with dedicated active quenching and recharging circuit. Each cell has a pitch of 26μm with a fill factor of 48%. The SPADs have been binned in order to realize a large photosensitive area detector exhibiting a reasonably low dark count rate (DCR) and reduced dead time, as required in a fast measurement system. A memory has also been implemented in order to enable only low DCR SPADs, so that a total DCR of about 100kHz can be achieved for the whole photosensitive area. The digital output generated by the SPAD array is sent to a time-discriminator stage which allows a time-gated detection of the incident light. Two time-windows have been implemented in this architecture. Their time width is controlled by an on-chip digital PLL locked to the external laser clock whereas the width of the time-windows can be set within the range 500ps-10ns with a resolution of 500ps. Photons detected within each time window are then counted by two 10-bits digital counters. Time-interleaved operation has been

  8. High-yield bang time detector for the OMEGA laser

    NASA Astrophysics Data System (ADS)

    Glebov, V. Yu.; Stoeckl, C.; Sangster, T. C.; Mileham, C.; Roberts, S.; Lerche, R. A.

    2006-10-01

    A simple, low-cost, high-yield neutron bang time (HYNBT) detector has been developed and implemented on the 60-beam, 30kJ OMEGA Laser Facility at the University of Rochester's Laboratory for Laser Energetics. The HYNBT consists of three chemical-vapor deposition diamond detectors of different sizes and sensitivities placed in a lead-shielded housing. The HYNBT is located in a reentrant tube 50cm from the center of the target chamber. The HYNBT has been temporally cross calibrated against the streak-camera-based neutron temporal diagnostic (NTD) for both D2 and DT implosions. The HYNBT has an internal time resolution better than 20ps and is able to measure bang time for yields above 1010 for DT and 5×1010 for D2 implosions. The implementation of the HYNBT on the National Ignition Facility will be discussed.

  9. Precise timing calibration for MoNA and LISA detectors

    NASA Astrophysics Data System (ADS)

    Garrett, Sierra; Barker, Alyson; Taylor, Nathaniel; Rogers, Warren F.; MoNA Collaboration

    2013-10-01

    The Modular Neutron Array (MoNA) and the Large multi-Institutional Scintillator Array (LISA), working in conjunction with the Sweeper Magnet and Detector Chamber at the NSCL, MSU, are used to determine the properties of neutron-unbound ground and excited states of neutron-rich nuclei. In order to determine the decay energy, precise energy and trajectory for both the charged fragment and the neutron need to be determined. This requires very precise time calibration for each of the 288 scintillator detectors in the two neutron arrays. Initial timing calibrations for all bars in a vertical layer are achieved using muons passing through all 16 detectors, taking into account the muon transit time from bar to bar. Vertical layers are then ``tied'' to one another using the arrival times of gamma rays originating from the target during production runs. In the LISA commissioning experiment, prompt gamma rays from the contaminant beam 29Na were used instead of those from the 26F production beam since they constituted 98% of the beam intensity (compared with the 26F production beam). Results for the LISA commissioning experiment will be presented. Work supported by NSF grant PHY-1101745.

  10. Time-domain response of the ARIANNA detector

    NASA Astrophysics Data System (ADS)

    Barwick, S. W.; Berg, E. C.; Besson, D. Z.; Duffin, T.; Hanson, J. C.; Klein, S. R.; Kleinfelder, S. A.; Piasecki, M.; Ratzlaff, K.; Reed, C.; Roumi, M.; Stezelberger, T.; Tatar, J.; Walker, J.; Young, R.; Zou, L.

    2015-03-01

    The Antarctic Ross Ice Shelf Antenna Neutrino Array (ARIANNA) is a high-energy neutrino detector designed to record the Askaryan electric field signature of cosmogenic neutrino interactions in ice. To understand the inherent radio-frequency (RF) neutrino signature, the time-domain response of the ARIANNA RF receiver must be measured. ARIANNA uses Create CLP5130-2N log-periodic dipole arrays (LPDAs). The associated effective height operator converts incident electric fields to voltage waveforms at the LDPA terminals. The effective height versus time and incident angle was measured, along with the associated response of the ARIANNA RF amplifier. The results are verified by correlating to field measurements in air and ice, using oscilloscopes. Finally, theoretical models for the Askaryan electric field are combined with the detector response to predict the neutrino signature.

  11. Measuring Sulfur Isotope Ratios from Solid Samples with the Sample Analysis at Mars Instrument and the Effects of Dead Time Corrections

    NASA Technical Reports Server (NTRS)

    Franz, H. B.; Mahaffy, P. R.; Kasprzak, W.; Lyness, E.; Raaen, E.

    2011-01-01

    The Sample Analysis at Mars (SAM) instrument suite comprises the largest science payload on the Mars Science Laboratory (MSL) "Curiosity" rover. SAM will perform chemical and isotopic analysis of volatile compounds from atmospheric and solid samples to address questions pertaining to habitability and geochemical processes on Mars. Sulfur is a key element of interest in this regard, as sulfur compounds have been detected on the Martian surface by both in situ and remote sensing techniques. Their chemical and isotopic composition can belp constrain environmental conditions and mechanisms at the time of formation. A previous study examined the capability of the SAM quadrupole mass spectrometer (QMS) to determine sulfur isotope ratios of SO2 gas from a statistical perspective. Here we discuss the development of a method for determining sulfur isotope ratios with the QMS by sampling SO2 generated from heating of solid sulfate samples in SAM's pyrolysis oven. This analysis, which was performed with the SAM breadboard system, also required development of a novel treatment of the QMS dead time to accommodate the characteristics of an aging detector.

  12. Evaluation of the time of uncapping and removing dead brood from cells by hygienic and non-hygienic honey bees.

    PubMed

    Palacio, Maria Alejandra; Flores, Jose Manuel; Figini, Emilio; Ruffinengo, Sergio; Escande, Alberto; Bedascarrasbure, Enrique; Rodriguez, Edgardo; Gonçalves, Lionel Segui

    2005-03-31

    Most research on hygienic behavior has recorded the time taken by the colony to remove an experimental amount of dead brood, usually after one or two days. We evaluated the time that hygienic (H) and non-hygienic (NH) honey bees take to uncap and remove dead brood in observation hives after the brood was killed using the pin-killing assay. Four experimental colonies were selected as the extreme cases among 108 original colonies. Thirty brood cells were perforated with a pin in two H and two NH colonies and observations were made after 1, 2, 3, 4, 5, 6, and 24 h. Different stages of uncapping and removing were recorded. Differences in uncapping and removal between H and NH colonies were significant for all comparisons made at the different times after perforation. Using observation hives one obtains a better and faster discrimination between H and NH colonies than in full size colonies. It is possible to differentiate H and NH within a few hours after perforating the cells.

  13. Time correlations of high energy muons in an underground detector

    NASA Astrophysics Data System (ADS)

    Becherini, Y.; Cecchini, S.; Chiarusi, T.; Cozzi, M.; Dekhissi, H.; Derkaoui, J.; Esposito, L. S.; Giacomelli, G.; Giorgini, M.; Giglietto, N.; Maaroufi, F.; Mandrioli, G.; Margiotta, A.; Manzoor, S.; Moussa, A.; Patrizii, L.; Popa, V.; Sioli, M.; Sirri, G.; Spurio, M.; Togo, V.

    2005-04-01

    We present the result of a search for correlations in the arrival times of high energy muons collected from 1995 till 2000 with the streamer tube system of the complete MACRO detector at the underground Gran Sasso Lab. Large samples of single muons (8.6 million), double muons (0.46 million) and multiple muons with multiplicities from 3 to 6 (0.08 million) were selected. These samples were used to search for time correlations of cosmic ray particles coming from the whole upper hemisphere or from selected space cones. The results of our analyses confirm with high statistics a random arrival time distribution of high energy cosmic rays.

  14. Optimizing timing performance of silicon photomultiplier-based scintillation detectors

    PubMed Central

    Yeom, Jung Yeol; Vinke, Ruud

    2013-01-01

    Precise timing resolution is crucial for applications requiring photon time-of-flight (ToF) information such as ToF positron emission tomography (PET). Silicon photomultipliers (SiPM) for PET, with their high output capacitance, are known to require custom preamplifiers to optimize timing performance. In this paper, we describe simple alternative front-end electronics based on a commercial low-noise RF preamplifier and methods that have been implemented to achieve excellent timing resolution. Two radiation detectors with L(Y)SO scintillators coupled to Hamamatsu SiPMs (MPPC S10362–33-050C) and front-end electronics based on an RF amplifier (MAR-3SM+), typically used for wireless applications that require minimal additional circuitry, have been fabricated. These detectors were used to detect annihilation photons from a Ge-68 source and the output signals were subsequently digitized by a high speed oscilloscope for offline processing. A coincident resolving time (CRT) of 147 ± 3 ps FWHM and 186 ± 3 ps FWHM with 3 × 3 × 5 mm3 and with 3 × 3 × 20 mm3 LYSO crystal elements were measured, respectively. With smaller 2 × 2 × 3 mm3 LSO crystals, a CRT of 125 ± 2 ps FWHM was achieved with slight improvement to 121 ± 3 ps at a lower temperature (15°C). Finally, with the 20 mm length crystals, a degradation of timing resolution was observed for annihilation photon interactions that occur close to the photosensor compared to shallow depth-of-interaction (DOI). We conclude that commercial RF amplifiers optimized for noise, besides their ease of use, can produce excellent timing resolution comparable to best reported values acquired with custom readout electronics. On the other hand, as timing performance degrades with increasing photon DOI, a head-on detector configuration will produce better CRT than a side-irradiated setup for longer crystals. PMID:23369872

  15. Analysis of regional travel time data from the November 1999 dead sea explosions observed in Saudi Arabia

    SciTech Connect

    Rodgers, A; Abdullah, M S; Ar-Rajehi, A; Al-Khalifah, T; Al-Amri, M S; Al-Haddad, M S; Al-Arifi, N

    2000-04-19

    Two large chemical explosions were detonated in the Dead Sea in order to calibrate seismic travel times and improve location accuracy for the International Monitoring System (IMS) to monitor a Comprehensive Nuclear Test-Ban Treaty (CTBT). These explosions provided calibration data for regional seismic networks in the Middle East. In this paper we report analysis of seismic data from these shots as recorded by two seismic networks run by King Saud University (KSU) and King Abdulaziz City for Science and Technology (KACST) in Saudi Arabia. The shots were well observed in the distance range 180-480 km mostly to the south of the Dead Sea in the Gulf of Aqaba region of northwestern Saudi Arabia. An average one-dimensional velocity model for the paths was inferred from the travel times of the regional phases Pn, Pg and Sg. Short-period Sn phases were not observed. The velocity model features a thin crust (crustal thickness 26-30 km) and low velocities (average P-wave velocity 5.8-6.0 km/s), consistent with the extensional tectonics of the region and previous studies.

  16. Stabilization and analytical tuning rule of double-loop control scheme for unstable dead-time process

    NASA Astrophysics Data System (ADS)

    Ugon, B.; Nandong, J.; Zang, Z.

    2017-06-01

    The presence of unstable dead-time systems in process plants often leads to a daunting challenge in the design of standard PID controllers, which are not only intended to provide close-loop stability but also to give good performance-robustness overall. In this paper, we conduct stability analysis on a double-loop control scheme based on the Routh-Hurwitz stability criteria. We propose to use this unstable double-loop control scheme which employs two P/PID controllers to control first-order or second-order unstable dead-time processes typically found in process industries. Based on the Routh-Hurwitz stability necessary and sufficient criteria, we establish several stability regions which enclose within them the P/PID parameter values that guarantee close-loop stability of the double-loop control scheme. A systematic tuning rule is developed for the purpose of obtaining the optimal P/PID parameter values within the established regions. The effectiveness of the proposed tuning rule is demonstrated using several numerical examples and the result are compared with some well-established tuning methods reported in the literature.

  17. Discrete Counting of Short Lived Isotopes With Low Background Detectors

    DTIC Science & Technology

    2008-03-01

    assume that any dead time in the detector will have a negligible impact on the outcome. Thus, dead time can be ignored, allowing the foreground...window with an expectation value μ is given by ( | ) ! beP b b μμμ − = . (5) Because μ cannot be known, it must be measured experimentally. To do...

  18. A GIS-driven integrated real-time surveillance pilot system for national West Nile virus dead bird surveillance in Canada.

    PubMed

    Shuai, Jiangping; Buck, Peter; Sockett, Paul; Aramini, Jeff; Pollari, Frank

    2006-04-20

    An extensive West Nile virus surveillance program of dead birds, mosquitoes, horses, and human infection has been launched as a result of West Nile virus first being reported in Canada in 2001. Some desktop and web GIS have been applied to West Nile virus dead bird surveillance. There have been urgent needs for a comprehensive GIS services and real-time surveillance. A pilot system was developed to integrate real-time surveillance, real-time GIS, and Open GIS technology in order to enhance West Nile virus dead bird surveillance in Canada. Driven and linked by the newly developed real-time web GIS technology, this integrated real-time surveillance system includes conventional real-time web-based surveillance components, integrated real-time GIS components, and integrated Open GIS components. The pilot system identified the major GIS functions and capacities that may be important to public health surveillance. The six web GIS clients provide a wide range of GIS tools for public health surveillance. The pilot system has been serving Canadian national West Nile virus dead bird surveillance since 2005 and is adaptable to serve other disease surveillance. This pilot system has streamlined, enriched and enhanced national West Nile virus dead bird surveillance in Canada, improved productivity, and reduced operation cost. Its real-time GIS technology, static map technology, WMS integration, and its integration with non-GIS real-time surveillance system made this pilot system unique in surveillance and public health GIS.

  19. A GIS-driven integrated real-time surveillance pilot system for national West Nile virus dead bird surveillance in Canada

    PubMed Central

    Shuai, Jiangping; Buck, Peter; Sockett, Paul; Aramini, Jeff; Pollari, Frank

    2006-01-01

    Background An extensive West Nile virus surveillance program of dead birds, mosquitoes, horses, and human infection has been launched as a result of West Nile virus first being reported in Canada in 2001. Some desktop and web GIS have been applied to West Nile virus dead bird surveillance. There have been urgent needs for a comprehensive GIS services and real-time surveillance. Results A pilot system was developed to integrate real-time surveillance, real-time GIS, and Open GIS technology in order to enhance West Nile virus dead bird surveillance in Canada. Driven and linked by the newly developed real-time web GIS technology, this integrated real-time surveillance system includes conventional real-time web-based surveillance components, integrated real-time GIS components, and integrated Open GIS components. The pilot system identified the major GIS functions and capacities that may be important to public health surveillance. The six web GIS clients provide a wide range of GIS tools for public health surveillance. The pilot system has been serving Canadian national West Nile virus dead bird surveillance since 2005 and is adaptable to serve other disease surveillance. Conclusion This pilot system has streamlined, enriched and enhanced national West Nile virus dead bird surveillance in Canada, improved productivity, and reduced operation cost. Its real-time GIS technology, static map technology, WMS integration, and its integration with non-GIS real-time surveillance system made this pilot system unique in surveillance and public health GIS. PMID:16626490

  20. Quantum Detectors in Generic Non Flat FLRW Space-Times

    NASA Astrophysics Data System (ADS)

    Rabochaya, Yevgeniya; Zerbini, Sergio

    2016-05-01

    We discuss a quantum field theoretical approach, in which a quantum probe is used to investigate the properties of generic non-flat FLRW space-times. The probe is identified with a conformally coupled massless scalar field defined on a space-time with horizon and the procedure to investigate the local properties is realized by the use of Unruh-DeWitt detector and by the evaluation of the regularized quantum fluctuations. In the case of de Sitter space, the coordinate independence of our results is checked, and the Gibbons-Hawking temperature is recovered. A possible generalization to the electromagnetic probe is also briefly indicated.

  1. Multi-CFD Timing Estimators for PET Block Detectors

    SciTech Connect

    Ullisch, Marcus G.; Moses, William W.

    2006-05-05

    In a conventional PET system with block detectors, a timing estimator is created by generating the analog sum of the signals from the four photomultiplier tubes (PMT) in a module and discriminating the sum with a single constant fraction discriminator (CFD). The differences in the propagation time between the PMTs in the module can potentially degrade the timing resolution of the module. While this degradation is probably too small to affect performance in conventional PET imaging, it may impact the timing inaccuracy for time-of-flight PET systems (which have higher timing resolution requirements). Using a separate CFD for each PMT would allow for propagation time differences to be removed through calibration and correction in software. In this paper we investigate and quantify the timing resolution achievable when the signal from each of the 4 PMTs is digitized by a separate CFD. Several methods are explored for both obtaining values for the propagation time differences between the PMTs and combining the four arrival times to form a single timing estimator. We find that the propagation time correction factors are best derived through an exhaustive search, and that the ''weighted average'' method provides the best timing estimator. Using these methods, the timing resolution achieved with 4 CFDs (1052 {+-} 82 ps) is equivalent to the timing resolution with the conventional single CFD setup (1067 {+-} 158 ps).

  2. Detectors

    DOEpatents

    Orr, Christopher Henry; Luff, Craig Janson; Dockray, Thomas; Macarthur, Duncan Whittemore; Bounds, John Alan; Allander, Krag

    2002-01-01

    The apparatus and method provide techniques through which both alpha and beta emission determinations can be made simultaneously using a simple detector structure. The technique uses a beta detector covered in an electrically conducting material, the electrically conducting material discharging ions generated by alpha emissions, and as a consequence providing a measure of those alpha emissions. The technique also offers improved mountings for alpha detectors and other forms of detectors against vibration and the consequential effects vibration has on measurement accuracy.

  3. Precision timing detectors with cadmium-telluride sensor

    NASA Astrophysics Data System (ADS)

    Bornheim, A.; Pena, C.; Spiropulu, M.; Xie, S.; Zhang, Z.

    2017-09-01

    Precision timing detectors for high energy physics experiments with temporal resolutions of a few 10 ps are of pivotal importance to master the challenges posed by the highest energy particle accelerators such as the LHC. Calorimetric timing measurements have been a focus of recent research, enabled by exploiting the temporal coherence of electromagnetic showers. Scintillating crystals with high light yield as well as silicon sensors are viable sensitive materials for sampling calorimeters. Silicon sensors have very high efficiency for charged particles. However, their sensitivity to photons, which comprise a large fraction of the electromagnetic shower, is limited. To enhance the efficiency of detecting photons, materials with higher atomic numbers than silicon are preferable. In this paper we present test beam measurements with a Cadmium-Telluride (CdTe) sensor as the active element of a secondary emission calorimeter with focus on the timing performance of the detector. A Schottky type CdTe sensor with an active area of 1cm2 and a thickness of 1 mm is used in an arrangement with tungsten and lead absorbers. Measurements are performed with electron beams in the energy range from 2 GeV to 200 GeV. A timing resolution of 20 ps is achieved under the best conditions.

  4. Single photon detector design features

    NASA Astrophysics Data System (ADS)

    Zaitsev, Sergey V.; Kurochkin, Vladimir L.; Kurochkin, Yury V.

    2016-12-01

    In the report are discussed the laboratory test results of SPAD detectors with InGaAs / InP avalanche photodiodes, operating in Geiger mode. Device operating in synchronous mode with the dead timer setting for proper working conditions of photodiodes. The report materials will showing the functional block diagram of the detector, real operating signals in the receiver path and clock circuits and main results of measurements. The input signal of the synchronous detector is the clock, which determines the time positions of expected photons arrival. Increasing the clock speed 1-300 MHz or getting more time positions of the time grid, we provide increased capacity for time position code of signals, when QKD information transmitted over the nets. At the same time, the maximum attainable speed of photon reception is limited by diode dead time. Diode quantum noise are minimized by inclusion of a special time interval - dead time 0.1-10 usec, after each received and registered a photon. The lowest attainable value of the dead time is determined as a compromise between transients in electrical circuits, passive avalanche «quenching» circuit and thermal transients cooling crystal diode, after each avalanche pass though photodiode. Achievable time and speed parameters are discussed with specific examples of detectors.

  5. A geographic study of West Nile virus in humans, dead corvids and mosquitoes in Ontario using spatial scan statistics with a survival time application.

    PubMed

    Thomas-Bachli, A L; Pearl, D L; Berke, O; Parmley, E J; Barker, I K

    2017-02-20

    Surveillance of West Nile virus (WNv) in Ontario has included passive reporting of human cases and testing of trapped mosquitoes and dead birds found by the public. The dead bird surveillance programme was limited to testing within a public health unit (PHU) until a small number of birds test positive. These dead corvid and mosquito surveillance programmes have not been compared for their ability to provide early warning in geographic areas where human cases occur each year. Spatial scan statistics were applied to time-to-event survival data based on first cases of WNv in found dead corvids, mosquitoes and humans. Clusters identified using raw data were compared to clusters based on model-adjusted survival times to evaluate whether geographic and sociodemographic factors influenced their distribution. Statistically significant (p < .05) space-time clusters of PHUs with faster time to detection were found using each surveillance data stream. During 2002-2004, the corvid surveillance programme outperformed the mosquito programme in terms of time to WNv detection, while the clusters of first-positive mosquito pools were more spatially similar to first human cases. In 2006, a cluster of first-positive dead corvids was located in northern PHUs and preceded a cluster of early human cases that was identified after controlling for the influence of geographic region and sociodemographic profile. © 2017 Blackwell Verlag GmbH.

  6. Optimizing timing performance of silicon photomultiplier-based scintillation detectors.

    PubMed

    Yeom, Jung Yeol; Vinke, Ruud; Levin, Craig S

    2013-02-21

    Precise timing resolution is crucial for applications requiring photon time-of-flight (ToF) information such as ToF positron emission tomography (PET). Silicon photomultipliers (SiPM) for PET, with their high output capacitance, are known to require custom preamplifiers to optimize timing performance. In this paper, we describe simple alternative front-end electronics based on a commercial low-noise RF preamplifier and methods that have been implemented to achieve excellent timing resolution. Two radiation detectors with L(Y)SO scintillators coupled to Hamamatsu SiPMs (MPPC S10362-33-050C) and front-end electronics based on an RF amplifier (MAR-3SM+), typically used for wireless applications that require minimal additional circuitry, have been fabricated. These detectors were used to detect annihilation photons from a Ge-68 source and the output signals were subsequently digitized by a high speed oscilloscope for offline processing. A coincident resolving time (CRT) of 147 ± 3 ps FWHM and 186 ± 3 ps FWHM with 3 × 3 × 5 mm(3) and with 3 × 3 × 20 mm(3) LYSO crystal elements were measured, respectively. With smaller 2 × 2 × 3 mm(3) LSO crystals, a CRT of 125 ± 2 ps FWHM was achieved with slight improvement to 121 ± 3 ps at a lower temperature (15° C). Finally, with the 20 mm length crystals, a degradation of timing resolution was observed for annihilation photon interactions that occur close to the photosensor compared to shallow depth-of-interaction (DOI). We conclude that commercial RF amplifiers optimized for noise, besides their ease of use, can produce excellent timing resolution comparable to best reported values acquired with custom readout electronics. On the other hand, as timing performance degrades with increasing photon DOI, a head-on detector configuration will produce better CRT than a side-irradiated setup for longer crystals.

  7. PID controller tuning for the first-order-plus-dead-time process model via Hermite-Biehler theorem.

    PubMed

    Roy, Anindo; Iqbal, Kamran

    2005-07-01

    This paper discusses PID stabilization of a first-order-plus-dead-time (FOPDT) process model using the stability framework of the Hermite-Biehler theorem. The FOPDT model approximates many processes in the chemical and petroleum industries. Using a PID controller and first-order Padé approximation for the transport delay, the Hermite-Biehler theorem allows one to analytically study the stability of the closed-loop system. We derive necessary and sufficient conditions for stability and develop an algorithm for selection of stabilizing feedback gains. The results are given in terms of stability bounds that are functions of plant parameters. Sensitivity and disturbance rejection characteristics of the proposed PID controller are studied. The results are compared with established tuning methods such as Ziegler-Nichols, Cohen-Coon, and internal model control.

  8. On oscillation reduction in feedback control for processes with an uncertain dead time and internal-external disturbances.

    PubMed

    Zhang, Yuqiong; Li, Donghai; Gao, Zhiqiang; Zheng, Qinling

    2015-11-01

    This paper aims to find a practical solution to reduce oscillation on the Smith Predictor (SP) based design with the dead time (DT) uncertainty, making it less sensitive to DT change and more effective in disturbance rejection. First, a conditional feedback mechanism is introduced in SP to reduce the amount of oscillation caused by the model inaccuracies in the DT parameter. Then, to address the oscillation caused by the phase lag in traditional PI controller and uncertain dynamics, this conditional SP is combined with active disturbance rejection control (ADRC), assisted by the knowledge of process dynamics. A practical tuning method is provided for the practicing engineers. The proposed approach is validated in extensive simulation studies with different types of plants and in frequency domain analysis. The simulation results show significant improvements in performance robustness and transient response. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  9. Time-of-flight detector for heavy ion backscattering spectrometry

    SciTech Connect

    Knapp, J.A.; Banks, J.C.; Doyle, B.L.

    1994-04-01

    This report describes the results of a two-year laboratory directed research and development project to explore advanced concepts in Heavy Ion Backscattering Spectrometry (HIBS), undertaken with the goal of extending the sensitivity of this relatively new technique to levels unattainable by any other existing trace element surface analysis. Improvements in sensitivity are required for the application of HIBS to contamination control in the microelectronics industry. Tools with sensitivity approaching 10{sup 8} atoms/cm{sup 2} are expected to be essential for enabling advanced IC production by the year 2000. During the project the authors developed a new analysis chamber with channeling goniometer and a prototype time-of-flight detector with a demonstrated sensitivity of {approximately} 5 {times} 10{sup 8} atoms/cm{sup 2} for Au on Si and {approximately} 5 {times} 10{sup 10} for Fe, and sufficient mass resolution to separate contributions from Fe and Cu.

  10. Drug infusion system manifold dead-volume impacts the delivery response time to changes in infused medication doses in vitro and also in vivo in anesthetized swine.

    PubMed

    Lovich, Mark A; Wakim, Matthew G; Wei, Abraham; Parker, Michael J; Maslov, Mikhail Y; Pezone, Matthew J; Tsukada, Hisashi; Peterfreund, Robert A

    2013-12-01

    IV infusion systems can be configured with manifolds connecting multiple drug infusion lines to transcutaneous catheters. Prior in vitro studies suggest that there may be significant lag times for drug delivery to reflect changes in infusion rates set at the pump, especially with low drug and carrier flows and larger infusion system dead-volumes. Drug manifolds allow multiple infusions to connect to a single catheter port but add dead-volume. We hypothesized that the time course of physiological responses to drug infusion in vivo reflects the impact of dead-volume on drug delivery. The kinetic response to starting and stopping epinephrine infusion ([3 mL/h] with constant carrier flow [10 mL/h]) was compared for high- and low-dead-volume manifolds in vitro and in vivo. A manifold consisting of 4 sequential stopcocks with drug entering at the most upstream port was contrasted with a novel design comprising a tube with separate coaxial channels meeting at the downstream connector to the catheter, which virtually eliminates the manifold contribution to the dead-volume. The time to 50% (T50) and 90% (T90) increase or decrease in drug delivery in vitro or contractile response in a swine model in vivo were calculated for initiation and cessation of drug infusion. The time to steady state after initiation and cessation of drug infusion both in vitro and in vivo was much less with the coaxial low-dead-volume manifold than with the high-volume design. Drug delivery after initiation in vitro reached 50% and 90% of steady state in 1.4 ± 0.12 and 2.2 ± 0.42 minutes with the low-dead-volume manifold and in 7.1 ± 0.58 and 9.8 ± 1.6 minutes with the high-dead-volume manifold, respectively. The contractility in vivo reached 50% and 90% of the full response after drug initiation in 4.3 ± 1.3 and 9.9 ± 3.9 minutes with the low-dead-volume manifold and 11 ± 1.2 and 17 ± 2.6 minutes with the high-dead-volume manifold, respectively. Drug delivery in vitro decreased by 50% and 90

  11. Novel Solid-State Devices as Timing Detectors for Ion Time-of-Flight Measurements

    NASA Astrophysics Data System (ADS)

    Ogasawara, K.; Allegrini, F.; Desai, M. I.; Livi, S. A.

    2016-10-01

    This study reports on the performance of Avalanche Photodiode (APD) and Multi-Pixel Photon Counter (MPPC) as timing detectors for ion time-of-flight mass spectroscopy. APDs detect >10 keV ions directly, while MPPCs detect sub-keV secondary electrons.

  12. Real-time imaging detectors for portal imaging

    NASA Astrophysics Data System (ADS)

    Roehrig, Hans; Cheng, Chee-Wai

    1993-12-01

    This paper reviews the status of real-time imaging systems which are used in radiation-therapy for radiotherapy localization and verification. Imaging systems under review include (1) metal- fluorescent screens, optically coupled to video cameras; (2) metal-phosphor screen in direct contact with two-dimensional photo-diode array (flat panel detector); (3) two-dimensional liquid ionization chamber; and (4) linear diode arrays. These systems permit frequent verification during the treatment and have been shown to be very useful. Unfortunately the image quality achieved, while impressive considering the short time the devices have been on the market, is significantly inferior to that which is available from the metal/film combination (port film).

  13. Full Offline Reconstruction in Real Time with the LHCb Detector

    NASA Astrophysics Data System (ADS)

    Dziurda, Agnieszka

    2016-11-01

    This document describes the novel, unique in High Energy Physics, real-time alignment and calibration of the full LHCb detector. The LHCb experiment has been designed as a dedicated heavy flavour physics experiment focused on the reconstruction of c and b hadrons. The LHCb detector is a single-arm forward spectrometer, which measures proton-proton interactions at the LHC. The operational bunch crossing rate is several orders of magnitude above the current abilities of data recording and storage. Therefore, a trigger system has been implemented to reduce this rate to an acceptable value. The LHCb trigger system has been redesigned during the 2013-2015 long shutdown,achieving offline-quality alignment and calibration online. It also allows analyses to be performed entirely at the trigger level. In addition, having the best performing reconstruction in the trigger gives the possibility to fully use the particle identification selection criteria and greatly increases the efficiency, in particular for the selection of charm and strange hadron decays. This results in enhancing the physics programme of the LHCb experiment.

  14. Quantification of live and dead probiotic bacteria in lyophilised product by real-time PCR and by flow cytometry.

    PubMed

    Kramer, Mateja; Obermajer, Natasa; Bogovic Matijasić, Bojana; Rogelj, Irena; Kmetec, Vojko

    2009-10-01

    The basic requirement for probiotic bacteria to be able to exert expected positive effects is to be alive; therefore, appropriate quantification methods are crucial. Due to disadvantages of conventional microbiological methods, the bacterial quantification based on the nucleic acid detection is increasingly used. The objective of this study was to evaluate the possibility to use propidium monoazide (PMA) in combination with real-time polymerase chain reaction (PCR) method or LIVE/DEAD BacLight viability kit in combination with flow cytometry (FCM) for determination of probiotic bacteria in a lyophilised product containing Lactobacillus acidophilus LA-5 and Bifidobacterium animalis ssp. lactis BB-12. In addition, the viability of probiotic bacteria in lyophilised product during 3 months storage was investigated. In the product, the results of real-time PCR quantification of PMA-treated cells did not differ significantly from those of non-treated cells, which indicate that most of the bacterial cells retained the membrane integrity although they have lost the culturability. The results obtained by FCM analysis were comparable with those by PMA real-time PCR. In conclusion, the PMA real-time PCR and FCM determination of the viability of probiotic bacteria could complement the plate count method which considers only the culturable part of the population.

  15. Optical and UV Sensing Sealed Tube Microchannel Plate Imaging Detectors with High Time Resolution

    NASA Astrophysics Data System (ADS)

    Siegmund, O.; Vallerga, J.; Tremsin, A.; Hull, J.; Elam, J.; Mane, A.

    2014-09-01

    Microchannel plate (MCP) based imaging, photon time tagging detector sealed tube schemes have a unique set of operational features that enable high time resolution astronomical and remote sensing applications to be addressed. New detectors using the cross strip (XS), cross delay line (XDL), or stripline anode readouts, a wide range of photocathode types, and advanced MCP technologies have been implemented to improve many performance characteristics. A variety of sealed tubes have been developed including 18mm XS readout devices with GaAs and SuperGenII photocathodes, 25mm XDL readout devices with SuperGenII and GaN photocathodes, and 20 x 20 cm sealed tubes with bialkali photocathodes and strip line readout. One key technology that has just become viable is the ability to make MCPs using atomic layer deposition (ALD) techniques. This employs nanofabrication of the active layers of an MCP on a microcapillary array. This technique opens new performance opportunities, including, very large MCP areas (>20cm), very low intrinsic background, lower radiation induced background, much longer overall lifetime and gain stability, and markedly lower outgassing which can improve the sealed tube lifetime and ease of fabrication. The XS readout has been implemented in formats of 22mm, 50mm and 100mm, and uses MCP charge signals detected on two orthogonal layers of conductive fingers to encode event X-Y positions. We have achieved spatial resolution XS detectors better than 25 microns FWHM, with good image linearity while at low gain (<10^6), substantially increasing local counting rate capabilities and the overall tube lifetime. XS tubes with updated electronics can encode event rates of >5 MHz with ~12% dead time and event timing accuracy of ~100ps. XDL sealed tubes in 25mm format demonstrate ~40 micron spatial resolution at up to ~2 MHz event rates, and have been developed with SupergenII visible regime photocathodes. The XDL tubes also achieve ~100 ps time resolution. Most

  16. Insufficient differentiation of live and dead Campylobacter jejuni and Listeria monocytogenes cells by ethidium monoazide (EMA) compromises EMA/real-time PCR.

    PubMed

    Flekna, Gabriele; Stefanic, Polonca; Wagner, Martin; Smulders, Frans J M; Mozina, Sonja Smole; Hein, Ingeborg

    2007-06-01

    Recently, ethidium monoazide (EMA) has been proposed as a means of reducing the real-time PCR signal originating from free DNA and dead bacterial cells by selectively entering damaged cells and blocking the DNA for PCR amplification via photoactivation. The present study investigated the effect of EMA on viable and dead bacterial cells using real-time PCR, plate count method and microscopy. The foodborne pathogens Campylobacter jejuni and Listeria monocytogenes were used as a Gram-negative and a Gram-positive model organism, respectively. EMA/real-time PCR analysis of heat-treated cultures of C. jejuni and L. monocytogenes containing 2.6x10(5) and 4x10(5) viable and 3x10(6) and 2x10(6) dead cells/ml, respectively, yielded 2x10(3) and 5.2x10(4) bacterial cell equivalents/ml after EMA treatment, thus underestimating the viable cell count in the samples. Similar results were obtained when analyzing late exponential phase cultures of C. jejuni and L. monocytogenes. Inhibition of growth by EMA was observed. It depended on the concentration of the bacterial cells present in the sample and the EMA concentration used (100-1 microg/ml). An EMA concentration at which dead cells would stain brightly and viable cells would not stain at all or would be very pale was not identified, as revealed by comparison with the results of a commercial live/dead stain. The results suggest that EMA influences not only dead but also viable cells of C. jejuni and L. monocytogenes. Thus EMA/real-time PCR is a poor indicator of cell viability.

  17. Dead on Arrival: Adapting Games to Finish at a Given Time or Location

    NASA Astrophysics Data System (ADS)

    von Öhsen, Arne; Loviscach, Jörn

    Casual and other games often serve as time-killing applications, be it on the commuter train or in the back seat of a shared car. When one arrives at the destination, the game has to be interrupted or aborted, which is annoying or even frustrating. Hence, we propose to continuously adapt the game’s level of difficulty to the estimated remaining time to arrival. This can be preset as a number of minutes or can continuously be estimated from the player’s position in relation to a predefined destination. Our dungeon-style prototype is based on an automated engine for content placement and can also make use of GPS data. We report on preliminary results from user tests.

  18. Finite time measurements by Unruh-DeWitt detector and Landauer's principle

    NASA Astrophysics Data System (ADS)

    Shevchenko, V.

    2017-06-01

    The model of Unruh-DeWitt detector coupled to the scalar field for finite time is studied. A systematic way of computing finite time corrections in various cases is suggested and nonperturbative effects like thermalization are discussed. It is shown in particular that adiabatic switching off the coupling between the detector and the thermal bath leaves non-vanishing corrections to the detector's levels distribution. Considering the two level detector as an information bearing degree of freedom encoding one bit of information, limits on external work for the detector's (de)coupling in finite time following from the Landauer's bound are formulated.

  19. Intermittent optical frequency measurements to reduce the dead time uncertainty of frequency link

    NASA Astrophysics Data System (ADS)

    Hachisu, Hidekazu; Ido, Tetsuya

    2015-11-01

    The absolute frequency of the 87Sr lattice clock transition was evaluated with an uncertainty of 1.1 × 10-15 using a frequency link to the international atomic time (TAI). The frequency uncertainty of a hydrogen maser used as a transfer oscillator was reduced by homogeneously distributed intermittent measurement over a five-day grid of TAI. Three sets of four or five days measurements as well as systematic uncertainty of the clock at 8.6 × 10-17 have resulted in an absolute frequency of 87Sr 1S0-3P0 clock transition to be 429 228 004 229 872.85 (47) Hz.

  20. A new timing model for calculating the intrinsic timing resolution of a scintillator detector.

    PubMed

    Shao, Yiping

    2007-02-21

    The coincidence timing resolution is a critical parameter which to a large extent determines the system performance of positron emission tomography (PET). This is particularly true for time-of-flight (TOF) PET that requires an excellent coincidence timing resolution (<1 ns) in order to significantly improve the image quality. The intrinsic timing resolution is conventionally calculated with a single-exponential timing model that includes two parameters of a scintillator detector: scintillation decay time and total photoelectron yield from the photon-electron conversion. However, this calculation has led to significant errors when the coincidence timing resolution reaches 1 ns or less. In this paper, a bi-exponential timing model is derived and evaluated. The new timing model includes an additional parameter of a scintillator detector: scintillation rise time. The effect of rise time on the timing resolution has been investigated analytically, and the results reveal that the rise time can significantly change the timing resolution of fast scintillators that have short decay time constants. Compared with measured data, the calculations have shown that the new timing model significantly improves the accuracy in the calculation of timing resolutions.

  1. Quantitative Changes in Hydrocarbons over Time in Fecal Pellets of Incisitermes minor May Predict Whether Colonies Are Alive or Dead

    PubMed Central

    Lewis, Vernard R.; Nelson, Lori J.; Baldwin, James A.

    2010-01-01

    Hydrocarbon mixtures extracted from fecal pellets of drywood termites are species-specific and can be characterized to identify the termites responsible for damage, even when termites are no longer present or are unable to be recovered easily. In structures infested by drywood termites, it is common to find fecal pellets, but difficult to sample termites from the wood. When fecal pellets appear after remedial treatment of a structure, it is difficult to determine whether this indicates that termites in the structure are still alive and active or not. We examined the hydrocarbon composition of workers, alates, and soldiers of Incisitermes minor (Hagen) (family Kalotermitidae) and of fecal pellets of workers. Hydrocarbons were qualitatively similar among castes and pellets. Fecal pellets that were aged for periods of 0, 30, 90, and 365 days after collection were qualitatively similar across all time periods, however, the relative quantities of certain individual hydrocarbons changed over time, with 19 of the 73 hydrocarbon peaks relatively increasing or decreasing. When the sums of the positive and negative slopes of these 19 hydrocarbons were indexed, they produced a highly significant linear correlation (R2 = 0.89). Consequently, the quantitative differences of these hydrocarbons peaks can be used to determine the age of worker fecal pellets, and thus help determine whether the colony that produced them is alive or dead. PMID:20882326

  2. Rise time of voltage pulses in NbN superconducting single photon detectors

    SciTech Connect

    Smirnov, K. V.; Divochiy, A. V.; Karpova, U. V.; Morozov, P. V.; Zotova, A. N.; Vodolazov, D. Yu.

    2016-08-01

    We have found experimentally that the rise time of voltage pulse in NbN superconducting single photon detectors increases nonlinearly with increasing the length of the detector L. The effect is connected with dependence of resistance of the detector R{sub n}, which appears after photon absorption, on its kinetic inductance L{sub k} and, hence, on the length of the detector. This conclusion is confirmed by our calculations in the framework of two temperature model.

  3. Enumeration of Viable Listeria monocytogenes Cells by Real-Time PCR with Propidium Monoazide and Ethidium Monoazide in the Presence of Dead Cells

    USDA-ARS?s Scientific Manuscript database

    Propidium monoazide (PMA) and ethidium monoazide were used for enumeration of viable Listeria monocytogenes cells in the presence of dead cells. PMA had no antimicrobial effect on L. monocytogenes. Viable cell counts were linearly related to real-time PCR threshold cycle values for PMA-treated cel...

  4. Ultrafast time measurements by time-correlated single photon counting coupled with superconducting single photon detector

    SciTech Connect

    Shcheslavskiy, V. Becker, W.; Morozov, P.; Divochiy, A.

    2016-05-15

    Time resolution is one of the main characteristics of the single photon detectors besides quantum efficiency and dark count rate. We demonstrate here an ultrafast time-correlated single photon counting (TCSPC) setup consisting of a newly developed single photon counting board SPC-150NX and a superconducting NbN single photon detector with a sensitive area of 7 × 7 μm. The combination delivers a record instrument response function with a full width at half maximum of 17.8 ps and system quantum efficiency ∼15% at wavelength of 1560 nm. A calculation of the root mean square value of the timing jitter for channels with counts more than 1% of the peak value yielded about 7.6 ps. The setup has also good timing stability of the detector–TCSPC board.

  5. Real-time self-networking radiation detector apparatus

    DOEpatents

    Kaplan, Edward; Lemley, James; Tsang, Thomas Y.; Milian, Laurence W.

    2007-06-12

    The present invention is for a radiation detector apparatus for detecting radiation sources present in cargo shipments. The invention includes the features of integrating a bubble detector sensitive to neutrons and a GPS system into a miniaturized package that can wirelessly signal the presence of radioactive material in shipping containers. The bubble density would be read out if such indicated a harmful source.

  6. Directional Dark Matter Detector Prototype (Time Projection Chamber)

    NASA Astrophysics Data System (ADS)

    Oliver-Mallory, Kelsey; Garcia-Sciveres, Maurice; Kadyk, John; Lopex-Thibodeaux, Mayra

    2013-04-01

    The time projection chamber is a mature technology that has emerged as a promising candidate for the directional detection of the WIMP particle. In order to utilize this technology in WIMP detection, the operational parameters must be chosen in the non-ideal regime. A prototype WIMP detector with a 10cm field cage, double GEM amplification, and ATLAS FEI3 pixel chip readout was constructed for the purpose of investigating effects of varying gas pressure in different gas mixtures. The rms radii of ionization clusters of photoelectrons caused by X-rays from a Fe-55 source were measured for several gas pressures between 760torr and 99torr in Ar(70)/ CO2(30), CF4, He(80)/Isobutane(20), and He(80)/CF4(20) mixtures. Average radii were determined from distributions of the data for each gas mixture and pressure, and revealed a negative correlation between pressure and radius in Ar(70)/CO2(30) and He(80)/Isobutane(20) mixtures. Investigation of the pressure-radius measurements are in progress using distributions of photoelectron and auger electron practical ranges (Univ. of Pisa) and diffusion, using the Garfield Monte Carlo program.

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

    PubMed

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

    2012-10-01

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

  8. Ultra-violet light-emitting diode calibration system for timing large area scintillation detectors

    NASA Astrophysics Data System (ADS)

    Naumov, P. Yu; Runtso, M. F.; Naumov, P. P.; Maklyaev, E. F.; Kaplin, V. A.; Fomin, V. S.; Razzhivin, I. S.; Melikyan, Yu A.

    2017-01-01

    Timing large area plastic scintillation detectors are developing for the space gamma-ray telescopes now. For the in-flight calibration of these detectors the use of ultra-violet light-emitting diode, irradiating the 1 m long detector module at the center of its lateral side is suggested. The results of the measurements show the possibility of this calibration system implementation as for amplitude as for timing properties monitoring.

  9. Landsat time series and lidar as predictors of live and dead basal area across five bark beetle-affected forests

    Treesearch

    Benjamin C. Bright; Andrew T. Hudak; Robert E. Kennedy; Arjan J. H. Meddens

    2014-01-01

    Bark beetle-caused tree mortality affects important forest ecosystem processes. Remote sensing methodologies that quantify live and dead basal area (BA) in bark beetle-affected forests can provide valuable information to forest managers and researchers. We compared the utility of light detection and ranging (lidar) and the Landsat-based detection of trends in...

  10. A method for considering the spatial variations of dead layer thickness in HPGe detectors to improve the FEPE calculation of bulky samples

    NASA Astrophysics Data System (ADS)

    Modarresi, S. Mohammad; Masoudi, S. Farhad; Karimi, Majid

    2017-01-01

    A method for considering the spatial variation of deal layer (DL) thickness at the lateral and top surfaces of HPGe detectors is proposed. Instead of considering the exact variation of DL thickness at detector surface, the lateral surface is divided into 12 segments, assuming each segments covers 30 degrees of the detector lateral surface and has a different DL thickness. Then, using Am-241 source at 12 positions on lateral surface and also on top surface of a HPGe detector, the nearest DL thickness for each segment can be selected through estimation of Full Energy Peak Efficiency (FEPE). This is the case in both experimental and simulation sides. The proposed detector can be used for FEPE calculation of bulk samples geometries such as Marinelli beaker containers. In order to check the suitability of proposed detector for bulky samples, a Marinelli beaker containing a set of standard radiation source solution with specified activities is considered. The experimental and simulation results of FEPE show good agreement with minimum 2% to maximum 6% relative difference from low (59.5 keV) to high energy (1.33 MeV) gamma ray.

  11. A direct electron detector for time-resolved MeV electron microscopy

    DOE PAGES

    Vecchione, T.; Denes, P.; Jobe, R. K.; ...

    2017-03-15

    The introduction of direct electron detectors enabled the structural biology revolution of cryogenic electron microscopy. Direct electron detectors are now expected to have a similarly dramatic impact on time-resolved MeV electron microscopy, particularly by enabling both spatial and temporal jitter correction. Here in this paper, we report on the commissioning of a direct electron detector for time-resolved MeV electron microscopy. The direct electron detector demonstrated MeV single electron sensitivity and is capable of recording megapixel images at 180 Hz. The detector has a 15-bit dynamic range, better than 30-μm spatial resolution and less than 20 analogue-to-digital converter count RMS pixelmore » noise. The unique capabilities of the direct electron detector and the data analysis required to take advantage of these capabilities are presented. The technical challenges associated with generating and processing large amounts of data are also discussed.« less

  12. A direct electron detector for time-resolved MeV electron microscopy

    NASA Astrophysics Data System (ADS)

    Vecchione, T.; Denes, P.; Jobe, R. K.; Johnson, I. J.; Joseph, J. M.; Li, R. K.; Perazzo, A.; Shen, X.; Wang, X. J.; Weathersby, S. P.; Yang, J.; Zhang, D.

    2017-03-01

    The introduction of direct electron detectors enabled the structural biology revolution of cryogenic electron microscopy. Direct electron detectors are now expected to have a similarly dramatic impact on time-resolved MeV electron microscopy, particularly by enabling both spatial and temporal jitter correction. Here we report on the commissioning of a direct electron detector for time-resolved MeV electron microscopy. The direct electron detector demonstrated MeV single electron sensitivity and is capable of recording megapixel images at 180 Hz. The detector has a 15-bit dynamic range, better than 30-μ m spatial resolution and less than 20 analogue-to-digital converter count RMS pixel noise. The unique capabilities of the direct electron detector and the data analysis required to take advantage of these capabilities are presented. The technical challenges associated with generating and processing large amounts of data are also discussed.

  13. Low-noise phase/frequency detector

    NASA Astrophysics Data System (ADS)

    McCorkle, J. W.

    1985-09-01

    The purpose of the research reported on in this thesis, is to demonstrate the effectiveness of a new circuit technique proposed by the author to eliminate the dead-zone anomaly in a digital phase/frequency detector. In addition to demonstrating the elimination of the dead zone, a new loop filter is described. The filter takes advantage of the new phase detector circuit technique so as to simultaneously provide both low-level reference sidebands and a lock-up time of one cycle of the reference. Phase detectors are used in control systems to measure the phase of one signal relative to the phase of another signal. Control systems of this type are usually referred to as Phase-Locked-Loops (PLL). Development of phase detectors has occurred because of the PLL application. A new phase detector is described in this paper.

  14. A real-time detector system for precise timing of audiovisual stimuli.

    PubMed

    Henelius, Andreas; Jagadeesan, Sharman; Huotilainen, Minna

    2012-01-01

    The successful recording of neurophysiologic signals, such as event-related potentials (ERPs) or event-related magnetic fields (ERFs), relies on precise information of stimulus presentation times. We have developed an accurate and flexible audiovisual sensor solution operating in real-time for on-line use in both auditory and visual ERP and ERF paradigms. The sensor functions independently of the used audio or video stimulus presentation tools or signal acquisition system. The sensor solution consists of two independent sensors; one for sound and one for light. The microcontroller-based audio sensor incorporates a novel approach to the detection of natural sounds such as multipart audio stimuli, using an adjustable dead time. This aids in producing exact markers for complex auditory stimuli and reduces the number of false detections. The analog photosensor circuit detects changes in light intensity on the screen and produces a marker for changes exceeding a threshold. The microcontroller software for the audio sensor is free and open source, allowing other researchers to customise the sensor for use in specific auditory ERP/ERF paradigms. The hardware schematics and software for the audiovisual sensor are freely available from the webpage of the authors' lab.

  15. An Efficient, FPGA-Based, Cluster Detection Algorithm Implementation for a Strip Detector Readout System in a Time Projection Chamber Polarimeter

    NASA Technical Reports Server (NTRS)

    Gregory, Kyle J.; Hill, Joanne E. (Editor); Black, J. Kevin; Baumgartner, Wayne H.; Jahoda, Keith

    2016-01-01

    A fundamental challenge in a spaceborne application of a gas-based Time Projection Chamber (TPC) for observation of X-ray polarization is handling the large amount of data collected. The TPC polarimeter described uses the APV-25 Application Specific Integrated Circuit (ASIC) to readout a strip detector. Two dimensional photoelectron track images are created with a time projection technique and used to determine the polarization of the incident X-rays. The detector produces a 128x30 pixel image per photon interaction with each pixel registering 12 bits of collected charge. This creates challenging requirements for data storage and downlink bandwidth with only a modest incidence of photons and can have a significant impact on the overall mission cost. An approach is described for locating and isolating the photoelectron track within the detector image, yielding a much smaller data product, typically between 8x8 pixels and 20x20 pixels. This approach is implemented using a Microsemi RT-ProASIC3-3000 Field-Programmable Gate Array (FPGA), clocked at 20 MHz and utilizing 10.7k logic gates (14% of FPGA), 20 Block RAMs (17% of FPGA), and no external RAM. Results will be presented, demonstrating successful photoelectron track cluster detection with minimal impact to detector dead-time.

  16. Imaging by time-tagging photons with the multi-anode microchannel array detector system

    NASA Technical Reports Server (NTRS)

    Timothy, J. G.; Morgan, J. S.

    1986-01-01

    The capability and initial use of the Multi-Anode Microchannel Array (MAMA) detector in the time-tag mode is reported. The detector hardware currently in use consists of a visible-light detector tube with a semitransparent photocathode proximity-focused to a high-gain curved-channel microchannel plate MCP. The photoevents are detected by a (256 x 1024)-pixel coincidence-anode array with pixel dimensions of 25 x 25 microns connected to charge-sensitive amplifiers and event-detection circuitry. In the time-lag mode, the detector delivers the pixel address and the time of arrival for each detected photon to an accuracy of 10 microns. The maximum count rate is limited by the speed of data-acquisition hardware. The MAMA detector in the time-lag mode is currently being evaluated in programs of astrometry and speckle imaging.

  17. Radiation detectors in nuclear medicine.

    PubMed

    Ranger, N T

    1999-01-01

    Single-photon-emitting or positron-emitting radionuclides employed in nuclear medicine are detected by using sophisticated imaging devices, whereas simpler detection devices are used to quantify activity for the following applications: measuring doses of radiopharmaceuticals, performing radiotracer bioassays, and monitoring and controlling radiation risk in the clinical environment. Detectors are categorized in terms of function, the physical state of the transducer, or the mode of operation. The performance of a detector is described by the parameters efficiency, energy resolution and discrimination, and dead time. A detector may be used to detect single events (pulse mode) or to measure the rate of energy deposition (current mode). Some detectors are operated as simple counting systems by using a single-channel pulse height analyzer to discriminate against background or other extraneous events. Other detectors are operated as spectrometers and use a multichannel analyzer to form an energy spectrum. The types of detectors encountered in nuclear medicine are gas-filled detectors, scintillation detectors, and semiconductor detectors. The ionization detector, Geiger-Müller detector, extremity and area monitor, dose calibrator, well counter, thyroid uptake probe, Anger scintillation camera, positron emission tomographic scanner, solid-state personnel dosimeter, and intraoperative probe are examples of detectors used in clinical nuclear medicine practice.

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

    SciTech Connect

    Zhang Qi; Zhao Kun; Chang Zenghu

    2010-07-15

    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.

  19. The Dead Sea

    NASA Technical Reports Server (NTRS)

    2006-01-01

    The Dead Sea is the lowest point on Earth at 418 meters below sea level, and also one of the saltiest bodies of water on Earth with a salinity of about 300 parts-per-thousand (nine times greater than ocean salinity). It is located on the border between Jordan and Israel, and is fed by the Jordan River. The Dead Sea is located in the Dead Sea Rift, formed as a result of the Arabian tectonic plate moving northward away from the African Plate. The mineral content of the Dead Sea is significantly different from that of ocean water, consisting of approximately 53% magnesium chloride, 37% potassium chloride and 8% sodium chloride. In the early part of the 20th century, the Dead Sea began to attract interest from chemists who deduced that the Sea was a natural deposit of potash and bromine. From the Dead Sea brine, Israel and Jordan produce 3.8 million tons potash, 200,000 tons elemental bromine, 45,000 tons caustic soda, 25, 000 tons magnesium metal, and sodium chloride. Both countries use extensive salt evaporation pans that have essentially diked the entire southern end of the Dead Sea.

    With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop

  20. The Dead Sea

    NASA Technical Reports Server (NTRS)

    2006-01-01

    The Dead Sea is the lowest point on Earth at 418 meters below sea level, and also one of the saltiest bodies of water on Earth with a salinity of about 300 parts-per-thousand (nine times greater than ocean salinity). It is located on the border between Jordan and Israel, and is fed by the Jordan River. The Dead Sea is located in the Dead Sea Rift, formed as a result of the Arabian tectonic plate moving northward away from the African Plate. The mineral content of the Dead Sea is significantly different from that of ocean water, consisting of approximately 53% magnesium chloride, 37% potassium chloride and 8% sodium chloride. In the early part of the 20th century, the Dead Sea began to attract interest from chemists who deduced that the Sea was a natural deposit of potash and bromine. From the Dead Sea brine, Israel and Jordan produce 3.8 million tons potash, 200,000 tons elemental bromine, 45,000 tons caustic soda, 25, 000 tons magnesium metal, and sodium chloride. Both countries use extensive salt evaporation pans that have essentially diked the entire southern end of the Dead Sea.

    With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop

  1. Risk assessment of false-positive quantitative real-time PCR results in food, due to detection of DNA originating from dead cells.

    PubMed

    Wolffs, Petra; Norling, Börje; Rådström, Peter

    2005-03-01

    Real-time PCR technology is increasingly used for detection and quantification of pathogens in food samples. A main disadvantage of nucleic acid detection is the inability to distinguish between signals originating from viable cells and DNA released from dead cells. In order to gain knowledge concerning risks of false-positive results due to detection of DNA originating from dead cells, quantitative PCR (qPCR) was used to investigate the degradation kinetics of free DNA in four types of meat samples. Results showed that the fastest degradation rate was observed (1 log unit per 0.5 h) in chicken homogenate, whereas the slowest rate was observed in pork rinse (1 log unit per 120.5 h). Overall results indicated that degradation occurred faster in chicken samples than in pork samples and faster at higher temperatures. Based on these results, it was concluded that, especially in pork samples, there is a risk of false-positive PCR results. This was confirmed in a quantitative study on cell death and signal persistence over a period of 28 days, employing three different methods, i.e. viable counts, direct qPCR, and finally floatation, a recently developed discontinuous density centrifugation method, followed by qPCR. Results showed that direct qPCR resulted in an overestimation of up to 10 times of the amount of cells in the samples compared to viable counts, due to detection of DNA from dead cells. However, after using floatation prior to qPCR, results resembled the viable count data. This indicates that by using of floatation as a sample treatment step prior to qPCR, the risk of false-positive PCR results due to detection of dead cells, can be minimized.

  2. Infrared detector Dewars - Increased LN2 hold time and vacuum jacket life spans

    NASA Technical Reports Server (NTRS)

    Jennings, D. E.; Boyd, W. J.; Blass, W. E.

    1976-01-01

    IR detector Dewars commonly suffer from shorter than desired LN2 hold times and insulation jacket vacuum corruption over relatively short time periods. In an attempt to solve this problem for a 9144 detector Dewar, small 1 liter/s appendage ion pumps were selected for continuous pumping of the vacuum jackets. This procedure extended LN2 hold times from 20 to 60 h and virtually eliminated vacuum jacket corruption. Thus the detector systems are usable continuously over periods of 6 months or more.

  3. Infrared detector Dewars - Increased LN2 hold time and vacuum jacket life spans

    NASA Technical Reports Server (NTRS)

    Jennings, D. E.; Boyd, W. J.; Blass, W. E.

    1976-01-01

    IR detector Dewars commonly suffer from shorter than desired LN2 hold times and insulation jacket vacuum corruption over relatively short time periods. In an attempt to solve this problem for a 9144 detector Dewar, small 1 liter/s appendage ion pumps were selected for continuous pumping of the vacuum jackets. This procedure extended LN2 hold times from 20 to 60 h and virtually eliminated vacuum jacket corruption. Thus the detector systems are usable continuously over periods of 6 months or more.

  4. Application of ethidium bromide monoazide for quantification of viable and dead cells of Salmonella enterica by real-time loop-mediated isothermal amplification.

    PubMed

    Wu, Guo Ping; Chen, Su Hua; Levin, Robert E

    2015-10-01

    A rapid and efficient method for quantification and discrimination of Salmonella enterica ser. Enteritidis between viable and dead cells killed by heat was developed using ethidium bromide monoazide (EMA) in combination with a real-time loop amplified (Rti-LAMP) DNA assay. The use of 8.0 μg/ml or less of EMA did not inhibit DNA amplification in Rti-LAMP assays derived from viable cells. However, 8.0 μg/ml of EMA notably inhibited DNA amplification and significantly increased the Tp values with dead cells. When the DNA from 2000 viable CFU was subjected to EMA-Rti-LAMP the resulting Tp value was 13 min. In contrast, the DNA from 2000 CFU completely heat destroyed CFU still yielded a Tp value, which was greatly increased to 33.1 min. When the DNA from viable plus heat killed CFU at a ratio of 7:1993 was subjected to EMA-Rti-LAMP, the resulting Tp value was 19.3 min, which was statistically identical (P<0.05) to the Tp value of 19.9 min. obtained with the DNA from only 7 viable CFU. These results indicate that even though 2000 dead cells yielded a Tp value of 33.1 min., low numbers of viable cells in the presence of much higher numbers of dead cells still yielded a linear plot for enumerating viable CFU from Tp values. In addition, propidium monoazide (PMA) was found to be ineffective in distinguishing between low numbers of viable and heat killed cells of S. enterica. Copyright © 2015. Published by Elsevier B.V.

  5. The investigation of timing large area scintillation detectors with SiPM light sensors properties

    NASA Astrophysics Data System (ADS)

    Runtso, M. F.; Naumov, P. Yu; Naumov, P. P.; Maklyaev, E. F.; Kaplin, V. A.; Fomin, V. S.; Razzhivin, I. S.; Melikyan, Yu A.

    2017-01-01

    The timing large area plastic scintillation detectors with silicon photomultipliers as photosensors properties were investigated using a cosmic radiation at the ground level. Different techniques of the amplitude spectra and efficiency measurements were implemented. The measurements results are presented.

  6. Estimate interaction timing in a large volume HgI2 detector using cathode pulse waveforms

    PubMed Central

    Meng, L.J.; He, Z.

    2016-01-01

    This paper presents experimental results on the timing resolution achieved with a 5 mm thick HgI2 detector. The timing information was derived based on the cathode pre-amplifier pulse waveform, measured using a digital oscilloscope. The times of interaction were estimated by fitting the measured pulse waveforms to pre-defined waveform models. With this approach, problems related to the conventional leading edge or constant fraction triggering, such as slow charge carrier mobility, pulse shape variation and depth-dependent detector response can be greatly reduced. As a result, we showed a 13 ns timing resolution measured using the 5 mm thick HgI2 detector and a BaF2 coincidence detector with 511 keV full energy events. In this paper, we discuss several waveform models and the results achieved using these models. PMID:28260824

  7. SiPM readout for the SHiP timing detector

    NASA Astrophysics Data System (ADS)

    Betancourt, C.; Bezshyiko, I.; Brundler, R.; Serra, N.; Storaci, B.

    2017-02-01

    The SHiP experiment is a new general purpose fixed target experiment proposed at the CERN SPS accelerator. A dedicated beam line in the North Area will be aimed at a fixed target station, followed by a magnetic shield to reduce beam induced background. The experiment will comprise a compact tau neutrino detector and a detector to search for hidden particles. Background rejection is ensured by use of background taggers and a dedicated timing detector. The timing detector will reduce combinatorial di-muon background by requiring incoming particles to be coincident in time within 100 ps. One option for the timing detector consists of columns of horizontal scintillating bars read-out on each end by Silicon Photomultiplier arrays. This study includes characterization of SiPMs from different manufacturers to be used in the timing detector in terms of Current-Voltage behavior, cross-talk probability, dark count rate and single photon timing resolution. Initial results of the time resolution of a EJ-200 scintillating bar read out on both ends by a single SiPM are presented.

  8. In vivo quantitative evaluation of live and dead bacteria in root canal infection by using propidium monoazide with real-time PCR.

    PubMed

    Kim, Sin-Young; Shin, Yooseok; Lee, Chan-Young; Jung, Il-Young

    2013-11-01

    For selective detection of viable bacteria with molecular methods, propidium monoazide (PMA) treatment has been successfully applied to a wide range of bacteria. The purpose of this study was to compare the quantity of live cells with the total amounts of both live and dead cells before and after chemomechanical preparation by using PMA in combination with real-time polymerase chain reaction (qPCR). Twenty-one teeth with pulp necrosis and a periapical lesion were included. Bacterial sampling of the root canals was performed before (S1) and after (S2) chemomechanical root canal treatment. Each sample was separated into 2 different tubes. PMA was added to one of the tubes, and the other was left untreated. Then, DNA extraction and qPCR were performed. To evaluate the validity of the PMA treatment, the defined mixtures containing different ratios of live and dead cell suspensions of Enterococcus faecalis were either subjected to PMA treatment or not subjected to PMA treatment, followed by qPCR quantification. A paired t test showed a highly significant difference in the mean threshold cycle values between S1 with and without PMA (P = .0002), and this difference (0.89) was similar to that (0.96) obtained from the samples consisting of 80% live cell suspension and 20% dead cell suspension of E. faecalis. The threshold cycle values between the S2 samples with and without PMA were also significantly different (P = .0134), and this difference (0.37) was similar to that obtained from the 100% live cell suspension of E. faecalis (0.42). PMA in conjunction with qPCR appeared to be useful in analyzing the primary infections of root canals because there were significant amounts of dead bacteria in the root canals. Although the use of PMA treatment in post-preparation samples significantly reduced the detection of dead bacteria, this difference was still small, so further studies should be carried out to confirm the necessity of PMA treatment. Copyright © 2013 American

  9. A new neutron time-of-flight detector for fuel-areal-density measurements on OMEGA

    SciTech Connect

    Glebov, V. Yu. Forrest, C. J.; Marshall, K. L.; Romanofsky, M.; Sangster, T. C.; Shoup, M. J.; Stoeckl, C.

    2014-11-15

    A new neutron time-of-flight (nTOF) detector for fuel-areal-density measurements in cryogenic DT implosions was installed on the OMEGA Laser System. The nTOF detector has a cylindrical thin-wall, stainless-steel, 8-in.-diam, 4-in.-thick cavity filled with an oxygenated liquid xylene scintillator. Four gated photomultiplier tubes (PMTs) with different gains are used to measure primary DT and D{sub 2} neutrons, down-scattered neutrons in nT and nD kinematic edge regions, and to study tertiary neutrons in the same detector. The nTOF detector is located 13.4 m from target chamber center in a well-collimated line of sight. The design details of the nTOF detector, PMT optimization, and test results on OMEGA will be presented.

  10. Compton rejection for HPGe detectors via real-time pulse shape analysis

    SciTech Connect

    Beckedahl, D; Blair, J J; Friensehner, A; Kammeraad, J E; Kreek, S A; Payne, B; Schmid, G J

    1998-07-31

    A Lawrence Livermore National Laboratory-developed pulse shape analysis (PSA) technique which performs real-time Compton suppression in High Purity Germanium (HPGe) detectors without the use of anti-coincidence detectors is described. Some preliminary measurements of a variety of sources with a standard HPGe detector system and our prototype PSA algorithm have been made and indicate that a reduction in Compton continuum can be achieved via PSA. These measurements represent an initial assessment of the effectiveness of the prototype PSA system for the improvement of spectral quality and future improvements are expected. Additional work is progressing to optimize the effectiveness of the algorithm for Compton rejection in standard HPGe detectors. Work is also progressing to extend the methodology to segmented HPGe detectors which could potentially yield significantly better Compton rejection and gamma-ray ima

  11. A new neutron time-of-flight detector for fuel-areal-density measurements on OMEGA.

    PubMed

    Glebov, V Yu; Forrest, C J; Marshall, K L; Romanofsky, M; Sangster, T C; Shoup, M J; Stoeckl, C

    2014-11-01

    A new neutron time-of-flight (nTOF) detector for fuel-areal-density measurements in cryogenic DT implosions was installed on the OMEGA Laser System. The nTOF detector has a cylindrical thin-wall, stainless-steel, 8-in.-diam, 4-in.-thick cavity filled with an oxygenated liquid xylene scintillator. Four gated photomultiplier tubes (PMTs) with different gains are used to measure primary DT and D2 neutrons, down-scattered neutrons in nT and nD kinematic edge regions, and to study tertiary neutrons in the same detector. The nTOF detector is located 13.4 m from target chamber center in a well-collimated line of sight. The design details of the nTOF detector, PMT optimization, and test results on OMEGA will be presented.

  12. A time-gating scintillation detector for the measurement of laser-induced fast neutrons

    SciTech Connect

    Lee, Sungman; Park, Sangsoon; Yea, Kwon-hae; Cha, Hyungki

    2009-06-15

    A time-gating scintillation detector, in which a fast high voltage switch is used for gating a channel photomultiplier, was developed for a measurement of laser-induced fast neutrons. The x rays generated from the intense femtosecond laser and the solid target interactions were suppressed selectively and a time-of-flight signal of a laser-generated fast neutron was measured effectively. The detector was used successfully to measure the neutron yield of a femtosecond, deuterated, polystyrene plasma.

  13. Note: A timing micro-channel plate detector with backside fast preamplifier

    SciTech Connect

    Wang, Wei; Yu, Deyang Lu, Rongchun; Liu, Junliang; Cai, Xiaohong

    2014-03-15

    A timing micro-channel plate detector with a backside double-channel fast preamplifier was developed to avoid distortion during signal propagation from the anode to the preamplifier. The mechanical and electronic structure is described. The detector including its backside preamplifier is tested by a {sup 241}Am α-source and a rise time of ∼2 ns with an output background noise of 4 mV{sub rms} was achieved.

  14. 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.

  15. Construction of the optical part of a time-of-flight detector prototype for the AFP detector.

    PubMed

    Nozka, L; Adamczyk, L; Avoni, G; Brandt, A; Buglewicz, P; Cavallaro, E; Chiodini, G; Chytka, L; Ciesla, K; Davis, P M; Dyndal, M; Grinstein, S; Hamal, P; Hrabovsky, M; Janas, K; Jirakova, K; Kocian, M; Komarek, T; Korcyl, K; Lange, J; Mandat, D; Michalek, V; Paz, I Lopez; Northacker, D; Rijssenbeek, M; Seabra, L; Schovanek, P; Staszewski, R; Swierska, P; Sykora, T

    2016-11-28

    We present the construction of the optical part of the ToF (time-of-flight) subdetector prototype for the AFP (ATLAS Forward Proton) detector. The ToF detector in conjunction with a 3D silicon pixel tracker will tag and measure protons originating in central exclusive interactions p + p → p + X + p, where the two outgoing protons are scattered in the very forward directions. The ToF is required to reduce so-called pileup backgrounds that arise from multiple proton interactions in the same bunch crossing at high luminosity. The background can fake the signal of interest, and the extra rejection from the ToF allows the proton tagger to operate at the high luminosity required for measurement of the processes. The prototype detector uses fused silica bars emitting Cherenkov radiation as a relativistic particle passes through it. The emitted Cherenkov photons are detected by a micro-channel plate multi-anode Photomultiplier Tube (MCP-PMT) and processed by fast electronics.

  16. Construction of the optical part of a time-of-flight detector prototype for the AFP detector

    SciTech Connect

    Nozka, L.; Adamczyk, L.; Avoni, G.; Brandt, A.; Buglewicz, P.; Cavallaro, E.; Chiodini, G.; Chytka, L.; Ciesla, K.; Davis, P. M.; Dyndal, M.; Grinstein, S.; Hamal, P.; Hrabovsky, M.; Janas, K.; Jirakova, K.; Kocian, M.; Komarek, T.; Korcyl, K.; Lange, J.; Mandat, D.; Michalek, V.; Paz, I. Lopez; Northacker, D.; Rijssenbeek, M.; Seabra, L.; Schovanek, P.; Staszewski, R.; Swierska, P.; Sykora, T.

    2016-11-22

    We present the construction of the optical part of the ToF (time-of-flight) subdetector prototype for the AFP (ATLAS Forward Proton) detector. The ToF detector in conjunction with a 3D silicon pixel tracker will tag and measure protons originating in central exclusive interactions p + p → p + X + p, where the two outgoing protons are scattered in the very forward directions. The ToF is required to reduce so-called pileup backgrounds that arise from multiple proton interactions in the same bunch crossing at high luminosity. The background can fake the signal of interest, and the extra rejection from the ToF allows the proton tagger to operate at the high luminosity required for measurement of the processes. The prototype detector uses fused silica bars emitting Cherenkov radiation as a relativistic particle passes through it. Finally, the emitted Cherenkov photons are detected by a micro-channel plate multi-anode Photomultiplier Tube (MCP-PMT) and processed by fast electronics.

  17. Construction of the optical part of a time-of-flight detector prototype for the AFP detector

    DOE PAGES

    Nozka, L.; Adamczyk, L.; Avoni, G.; ...

    2016-11-22

    We present the construction of the optical part of the ToF (time-of-flight) subdetector prototype for the AFP (ATLAS Forward Proton) detector. The ToF detector in conjunction with a 3D silicon pixel tracker will tag and measure protons originating in central exclusive interactions p + p → p + X + p, where the two outgoing protons are scattered in the very forward directions. The ToF is required to reduce so-called pileup backgrounds that arise from multiple proton interactions in the same bunch crossing at high luminosity. The background can fake the signal of interest, and the extra rejection from themore » ToF allows the proton tagger to operate at the high luminosity required for measurement of the processes. The prototype detector uses fused silica bars emitting Cherenkov radiation as a relativistic particle passes through it. Finally, the emitted Cherenkov photons are detected by a micro-channel plate multi-anode Photomultiplier Tube (MCP-PMT) and processed by fast electronics.« less

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  19. Precision blood-leak detector with high long-time stability

    NASA Astrophysics Data System (ADS)

    Georgiadis, Christos; Kleuver, Wolfram

    1999-11-01

    With this publication a precision blood-leak-detector is presented. The blood-leak-detector is used for recognition of fractures in the dialyzer of a kidney-machine. It has to detect safely a blood flow of ml/min to exclude any risk for the patient. A lot of systems exist for blood-leak-detection. All of them use the same principle. They detect the light absorption in the dialyze fluid. The actual used detectors are inferior to the new developed sensor in resolution and long-time stability. Regular test of the existing systems and high failure rates are responsible for the high maintenance.

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

    SciTech Connect

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

    2015-07-15

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

  1. Time and space reconstruction in optical, non-imaging, scintillator-based particle detectors

    NASA Astrophysics Data System (ADS)

    Galbiati, C.; McCarty, K.

    2006-12-01

    A new generation of ultra-low-background, non-imaging scintillator detectors is being developed to study solar neutrinos and search for dark matter. These detectors generally contain a "fiducial volume," where the signal to noise ratio is maximal, surrounded by an "active buffer region." To distinguish between events occurring in the two regions, the position of each event in space and time is reconstructed starting from the spatial and temporal distribution of the photons collected. The object of this paper is the study of the reconstruction, in time and space, of scintillation events in detectors of large dimensions. A general, likelihood-based method of position reconstruction for this class of detectors is presented. The potential spatial resolution of the method is then evaluated. It is shown that for a spherical detector with a large number N of photosensitive elements that detect photons, the expected spatial resolution at the center of the detector is given by δa≈(cσ/n)√{3/N}, where σ is the width of the scintillator time response function and n is the index of refraction in the medium. However, if light in the detector has a scattering mean free path much less than the detector radius R, so that the information on the time of detection of the photons becomes irrelevant, and only the spatial distribution of the detected photons is of essence, the resolution instead becomes (R/2)√{3/N}. Finally, a formalism is introduced to deal with the common case in which only the arrival time of the first photon to arrive at each photosensitive element can be measured.

  2. Photo-detectors for time of flight positron emission tomography (ToF-PET).

    PubMed

    Spanoudaki, Virginia Ch; Levin, Craig S

    2010-01-01

    We present the most recent advances in photo-detector design employed in time of flight positron emission tomography (ToF-PET). PET is a molecular imaging modality that collects pairs of coincident (temporally correlated) annihilation photons emitted from the patient body. The annihilation photon detector typically comprises a scintillation crystal coupled to a fast photo-detector. ToF information provides better localization of the annihilation event along the line formed by each detector pair, resulting in an overall improvement in signal to noise ratio (SNR) of the reconstructed image. Apart from the demand for high luminosity and fast decay time of the scintillation crystal, proper design and selection of the photo-detector and methods for arrival time pick-off are a prerequisite for achieving excellent time resolution required for ToF-PET. We review the two types of photo-detectors used in ToF-PET: photomultiplier tubes (PMTs) and silicon photo-multipliers (SiPMs) with a special focus on SiPMs.

  3. Photo-Detectors for Time of Flight Positron Emission Tomography (ToF-PET)

    PubMed Central

    Spanoudaki, Virginia Ch.; Levin⋆, Craig S.

    2010-01-01

    We present the most recent advances in photo-detector design employed in time of flight positron emission tomography (ToF-PET). PET is a molecular imaging modality that collects pairs of coincident (temporally correlated) annihilation photons emitted from the patient body. The annihilation photon detector typically comprises a scintillation crystal coupled to a fast photo-detector. ToF information provides better localization of the annihilation event along the line formed by each detector pair, resulting in an overall improvement in signal to noise ratio (SNR) of the reconstructed image. Apart from the demand for high luminosity and fast decay time of the scintillation crystal, proper design and selection of the photo-detector and methods for arrival time pick-off are a prerequisite for achieving excellent time resolution required for ToF-PET. We review the two types of photo-detectors used in ToF-PET: photomultiplier tubes (PMTs) and silicon photo-multipliers (SiPMs) with a special focus on SiPMs. PMID:22163482

  4. Time Resolved Detectors and Measurements for Accelerators and Beamlines at the Australian Synchrotron

    NASA Astrophysics Data System (ADS)

    Boland, M. J.; Rassool, R. P.; LeBlanc, G. S.; Peake, D. J.; Sobott, B. A.; Lee, V.; Schubert, A.; Kirby, N.

    2010-06-01

    Time resolved experiments require precision timing equipment and careful configuration of the machine and the beamline. The Australian Synchrotron has a state of the art timing system that allows flexible, real-time control of the machine and beamline timing parameters to target specific electron bunches. Results from a proof-of-principle measurement with a pulsed laser and a streak camera on the optical diagnostic beamline will be presented. The timing system was also used to fast trigger the PILATUS detector on an x-ray beamline to measure the fill pattern dependent effects of the detector. PILATUS was able to coarsely measure the fill pattern in the storage ring which implies that fill pattern intensity variations need to be corrected for when using the detector in this mode.

  5. Time Resolved Detectors and Measurements for Accelerators and Beamlines at the Australian Synchrotron

    SciTech Connect

    Boland, M. J.; Rassool, R. P.; Peake, D. J.; Sobott, B. A.; Lee, V.; Schubert, A.; LeBlanc, G. S.; Kirby, N.

    2010-06-23

    Time resolved experiments require precision timing equipment and careful configuration of the machine and the beamline. The Australian Synchrotron has a state of the art timing system that allows flexible, real-time control of the machine and beamline timing parameters to target specific electron bunches. Results from a proof-of-principle measurement with a pulsed laser and a streak camera on the optical diagnostic beamline will be presented. The timing system was also used to fast trigger the PILATUS detector on an x-ray beamline to measure the fill pattern dependent effects of the detector. PILATUS was able to coarsely measure the fill pattern in the storage ring which implies that fill pattern intensity variations need to be corrected for when using the detector in this mode.

  6. Estimation of time resolution for DOI-PET detector using diameter 0.2 mm WLS fibers

    SciTech Connect

    Kobayashi, A.; Ito, H.; Han, S.; Kaneko, N.; Kawai, H.; Kodama, S.; Han, S.; Kamada, K.; Shoji, Y.; Yoshikawa, A.

    2015-07-01

    We are developing the whole-body PET detector with high position resolution (1 mm) and low cost (1 M dollars). Scintillator plates, Wave Length Sifting Fibers and SiPMs are used. In this work, time resolution of our PET detector is estimated. Our detector may also have good time resolution such as a few ps. (authors)

  7. Recent detector developments at SINTEF (industrial presentation)

    NASA Astrophysics Data System (ADS)

    Sundby Avset, Berit; Evensen, Lars; Uri Jensen, Geir; Mo, Sjur; Kari Schjølberg-Henriksen; Westgaard, Trond

    1998-02-01

    Results from SINTEF's research on radiation hardness of silicon detectors, thin silicon detectors, silicon drift devices, reach-through avalanche photodiodes, and detectors with thin dead layers are presented.

  8. Versatile, reprogrammable area pixel array detector for time-resolved synchrotron x-ray applications

    SciTech Connect

    Gruner, Sol

    2010-05-01

    The final technical report for DOE grant DE-SC0004079 is presented. The goal of the grant was to perform research, development and application of novel imaging x-ray detectors so as to effectively utilize the high intensity and brightness of the national synchrotron radiation facilities to enable previously unfeasible time-resolved x-ray research. The report summarizes the development of the resultant imaging x-ray detectors. Two types of detector platforms were developed: The first is a detector platform (called a Mixed-Mode Pixel Array Detector, or MM-PAD) that can image continuously at over a thousand images per second while maintaining high efficiency for wide dynamic range signals ranging from 1 to hundreds of millions of x-rays per pixel per image. Research on an even higher dynamic range variant is also described. The second detector platform (called the Keck Pixel Array Detector) is capable of acquiring a burst of x-ray images at a rate of millions of images per second.

  9. TIME-TAG mode of STIS observations using the MAMA detectors

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash; Danks, Anthony; Baum, Stefi; Balzano, Vicki; Kraemer, Steve; Kutina, Ray; Sears, William

    1995-04-01

    We summarize the time-tag mode of STIS observations using the MAMA detectors, both in imaging and spectroscopic modes. After a brief outline on the MAMA detector characteristics and the astronomical applications of the time-tag mode, the general philosophy and the details of the data management strategy are described in detail. The GO specifications, and the consequent different modes of data transfer strategy are outlined. Restrictions on maximum data rates, integration times, and BUFFER-TIME requirements are explained. A few cases where the subarray option would be useful are outlined.

  10. Plasma Time in Discriminating Nuclear Recoils in Germanium Detector for Dark Matter Searches

    NASA Astrophysics Data System (ADS)

    Mei, Dongming; Barker, D'ann

    2012-10-01

    In the detection of WIMP-induced nuclear recoils with high-purity germanium detectors, CDMS-type bolometers are often used in measuring the ionization yield. For this technology, the detector is operated in the milli-Kelvin temperature range, which requires high priced detectors. Alternative electron/nuclear recoil discrimination using pulse shape has been widely utilized in the energy range of MeV in neutrinoless double-beta decay experiments with germanium detectors. However, the nuclear recoils induced by WIMPs are in the energy range of keV, and their pulse shape difference with electronic recoils in the same energy range has not proven to be visible in a commercially available germanium detector. This paper presents a new idea of using plasma time difference in pulse shape to discriminate nuclear recoils from electronic recoils. We show the plasma time difference as a function of nuclear recoil energy. The technique using plasma time will be discussed with a generic germanium detector.

  11. [Between science and moral injury--dead human bodies' treatment in anatomy and pathology during early modern times].

    PubMed

    Bauer, Axel W

    2005-01-01

    In this essay the history of anatomy and pathology between the 16th and the 19th century is focused under the two aspects of scientific development and of moral injury. In anatomy, which came along as a special field of theoretical medicine in 16th century, the human corpse was used as a suitable and to an increasing degree legitimate model of the healthy living body. About two hundred years later, even pathology started to be transformed into pathological anatomy. While anatomists were dealing with the structure of the healthy body pathological anatomists were interested in the morbid changes of the human corpse; the pathologist perceived the dead body as a static model of the dynamic pathological process in the living patient. Anatomy came along in the era of Renaissance and Humanism not least because of a close connection between science and the fine arts, whereas its practical relevance during the 16th and the 17th century resulted from a preparatory function for army surgery. The corpses of executed criminals, infanticides, and of unmarried mothers who had died from natural causes were often used for anatomical purposes including public autopsy. Pathological anatomy, however, unfolded its power not until the end of the 18th and the beginning of the 19th century when a new medical institution had been established: the clinic. The physical methods of examination such as percussion and auscultation of the patient's body could now be reviewed by the results of a post-mortem autopsy. The growing influence of pathological anatomy during 19th century medicine was reflected by a modified perception and evaluation of disease: The spatial dimensions of the visible findings received priority to the chronological development of the process of disease with the consequence of a heightened risk of separating the pathological structures from the suffering patient's biographical context. For the gain to scientism pathological anatomy had to tolerate a loss of reality

  12. SU-E-I-20: Dead Time Count Loss Compensation in SPECT/CT: Projection Versus Global Correction

    SciTech Connect

    Siman, W; Kappadath, S

    2014-06-01

    Purpose: To compare projection-based versus global correction that compensate for deadtime count loss in SPECT/CT images. Methods: SPECT/CT images of an IEC phantom (2.3GBq 99mTc) with ∼10% deadtime loss containing the 37mm (uptake 3), 28 and 22mm (uptake 6) spheres were acquired using a 2 detector SPECT/CT system with 64 projections/detector and 15 s/projection. The deadtime, Ti and the true count rate, Ni at each projection, i was calculated using the monitor-source method. Deadtime corrected SPECT were reconstructed twice: (1) with projections that were individually-corrected for deadtime-losses; and (2) with original projections with losses and then correcting the reconstructed SPECT images using a scaling factor equal to the inverse of the average fractional loss for 5 projections/detector. For both cases, the SPECT images were reconstructed using OSEM with attenuation and scatter corrections. The two SPECT datasets were assessed by comparing line profiles in xyplane and z-axis, evaluating the count recoveries, and comparing ROI statistics. Higher deadtime losses (up to 50%) were also simulated to the individually corrected projections by multiplying each projection i by exp(-a*Ni*Ti), where a is a scalar. Additionally, deadtime corrections in phantoms with different geometries and deadtime losses were also explored. The same two correction methods were carried for all these data sets. Results: Averaging the deadtime losses in 5 projections/detector suffices to recover >99% of the loss counts in most clinical cases. The line profiles (xyplane and z-axis) and the statistics in the ROIs drawn in the SPECT images corrected using both methods showed agreement within the statistical noise. The count-loss recoveries in the two methods also agree within >99%. Conclusion: The projection-based and the global correction yield visually indistinguishable SPECT images. The global correction based on sparse sampling of projections losses allows for accurate SPECT deadtime

  13. Time-of-flight calibration of a 6Li glass epithermal neutron detector

    PubMed

    Livingston; Saleh; Block; Brand

    2000-10-01

    The curing of Portland cement concrete involves the conversion of water from a free to a bound state. The process can be monitored nondestructively by measuring the shift in the neutron energy spectrum in the epithermal range (0.025-1 eV). A tuned array of 6Li glass detectors has been constructed with varying efficiencies over the epithermal energy range. To determine the efficiency of each detector as a function of neutron energy, it is necessary to calibrate it against a reference neutron spectrum. This was accomplished using a time-of-flight approach with a pulsed neutron beam produced at the Gaerttner LINAC Laboratory at Rensselaer Polytechnic Institute. With a neutron flight path of 25 m it was possible to determine the neutron detector efficiencies to an energy resolution of 11 microeV. The data showed good agreement with the detector design calculations.

  14. Parasitic antenna effect in terahertz plasmon detector array for real-time imaging system

    NASA Astrophysics Data System (ADS)

    Yang, Jong-Ryul; Lee, Woo-Jae; Ryu, Min Woo; Rok Kim, Kyung; Han, Seong-Tae

    2015-10-01

    The performance uniformity of each pixel integrated with a patch antenna in a terahertz plasmon detector array is very important in building the large array necessary for a real-time imaging system. We found a parasitic antenna effect in the terahertz plasmon detector whose response is dependent on the position of the detector pixel in the illumination area of the terahertz beam. It was also demonstrated that the parasitic antenna effect is attributed to the physical structure consisting of signal pads, bonding wires, and interconnection lines on a chip and a printed circuit board. Experimental results show that the performance of the detector pixel is determined by the sum of the effects of each parasitic antenna and the on-chip integrated antenna designed to detect signals at the operating frequency. The parasitic antenna effect can be minimized by blocking the interconnections with a metallic shield.

  15. Novel time-dependent alignment of the ATLAS Inner Detector in the LHC Run 2

    NASA Astrophysics Data System (ADS)

    Jiménez Peña, J.

    2016-11-01

    ATLAS is a multipurpose experiment at the LHC proton-proton collider. Its physics goals require an unbiased and high resolution measurement of the charged particle kinematic parameters. These critically depend on the layout and performance of the tracking system and the quality of the alignment of its components. For the LHC Run 2, the system has been upgraded with the installation of a new pixel layer, the Insertable B-layer (IBL) . ATLAS Inner Detector alignment framework has been adapted and upgraded to correct very short time scale movements of the sub-detectors. In particular, a mechanical distortion of the IBL staves up to 20 μm and a vertical displacement of the Pixel detector of ~ 6 μm have been observed during data-taking. The techniques used to correct for these effects and to match the required Inner Detector performance will be presented.

  16. Time-resolved step-scan infrared imaging system utilizing a linear array detector.

    PubMed

    Sugiyama, Hiroshi; Koshoubu, Jun; Kashiwabara, Seiichi; Nagoshi, Toshiyuki; Larsen, Richard A; Akao, Kenichi

    2008-01-01

    A time-resolved infrared (IR) imaging system combined with a multichannel IR microscope, which utilizes a 16 channel linear array (LA) detector, and step-scan Fourier transform infrared (FT-IR) microscope was developed. The LA detector integrates a readout circuit on each detector element, so the detected signals can be read simultaneously. Thus, this system can perform high speed imaging using the step-scan method, similar to a single channel detector. To verify the capabilities of this system, a reflective sample was examined whose position was altered using a piezo actuator activated by an alternating voltage. In addition, the localization of relaxation dynamics for the liquid crystal (LC) molecules in an LC cell under oscillating electric field conditions was detected by this system.

  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. Development of real time detector for fluorescent particles

    SciTech Connect

    Prevost, C.; Vendel, J.; Seigneur, A.

    1997-08-01

    Aerosols tagged by a fluorescent dye are a worthwhile tool within the framework of ventilation and filtration studies. The detection in real time of a specific particulate tracer allows characterization of ventilation behaviour such as air change rate, the determination of a good or bad mixing zone and transfer coefficient, or the determination of the decontamination factor for High Efficiency Particulate Air (HEPA) filters. Generally, these tests require specific aerosols in order to get rid of the atmospheric aerosol background. Until now the principle of fluorescent aerosol concentration measuring has only allowed an integral response with a time lag by means of sampling on filters and a fluorimetric analysis after specific conditioning of these filters. 5 refs., 13 figs.

  19. Discriminating cosmic muons and X-rays based on rise time using a GEM detector

    NASA Astrophysics Data System (ADS)

    Wu, Hui-Yin; Zhao, Sheng-Ying; Wang, Xiao-Dong; Zhang, Xian-Ming; Qi, Hui-Rong; Zhang, Wei; Wu, Ke-Yan; Hu, Bi-Tao; Zhang, Yi

    2016-08-01

    Gas electron multiplier (GEM) detectors have been used in cosmic muon scattering tomography and neutron imaging over the last decade. In this work, a triple GEM device with an effective readout area of 10 cm × 10 cm is developed, and a method of discriminating between cosmic muons and X-rays based on rise time is tested. The energy resolution of the GEM detector is tested by 55Fe ray source to prove the GEM detector has a good performance. Analysis of the complete signal-cycles allows us to get the rise time and pulse heights. The experiment result indicates that cosmic muons and X-rays can be discriminated with an appropriate rise time threshold. Supported by National Natural Science Foundation of China (11135002, 11275235, 11405077, 11575073)

  20. Time of flight elastic recoil detection analysis with a position sensitive detector

    SciTech Connect

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

    2010-03-15

    A position sensitive detection system based on the microchannel plate detector has been constructed and installed at the existing time of flight (TOF) spectrometer in order to perform a kinematic correction and improve the surface time/depth resolution of elastic recoil detection analysis (ERDA) system. The position resolution of the detector has been tested for different types of ions and anode voltages. TOF spectra of recoiled O ions from SiO{sub 2} and F from CaF{sub 2} were collected in coincidence with position sensitive detector signal. Kinematic correction of TOF spectra improved surface time/depth resolution by {approx}20% for our system; however even higher improvements could be obtained in larger solid angle TOF-ERDA systems.

  1. Towards a life-time-limited 8-octave-infrared photoconductive germanium detector

    NASA Astrophysics Data System (ADS)

    Pavlov, S. G.; Deßmann, N.; Pohl, A.; Abrosimov, N. V.; Mittendorff, M.; Winnerl, S.; Zhukavin, R. Kh; Tsyplenkov, V. V.; Shengurov, D. V.; Shastin, V. N.; Hübers, H.-W.

    2015-10-01

    Ultrafast, ultra-broad-band photoconductive detector based on heavily doped and highly compensated germanium has been demonstrated. Such a material demonstrates optical sensitivity in the more than 8 octaves, in the infrared, from about 2 mm to about 8 μm. The spectral sensitivity peaks up between 2 THz and 2.5 THz and is slowly reduced towards lower and higher frequencies. The life times of free electrons/holes measured by a pump-probe technique approach a few tenths of picoseconds and remain almost independent on the optical input intensity and on the temperature of a detector in the operation range. During operation, a detector is cooled down to liquid helium temperature but has been approved to detect, with a reduced sensitivity, up to liquid nitrogen temperature. The response time is shorter than 200 ps that is significantly faster than previously reported times.

  2. Real-time alignment and cali bration of the LHCb Detector in Run II

    NASA Astrophysics Data System (ADS)

    Dujany, Giulio; Storaci, Barbara

    2015-12-01

    Stable, precise spatial alignment and PID calibration are necessary to achieve optimal detector performance. During Run2, LHCb will have a new real-time detector alignment and calibration to allow equivalent performance in the online and offline reconstruction to be reached. This offers the opportunity to optimise the event selection by applying stronger constraints, and to use hadronic particle identification at the trigger level. The computing time constraints are met through the use of a new dedicated framework using the multi-core farm infrastructure for the trigger. The motivation for a real-time alignment and calibration of the LHCb detector is discussed from the operative and physics performance point of view. Specific challenges of this configuration are discussed, as well as the designed framework and its performance.

  3. Measurement of the directional sensitivity of Dark Matter Time Projection Chamber detectors

    NASA Astrophysics Data System (ADS)

    Deaconu, Cosmin; Leyton, Michael; Corliss, Ross; Druitt, Gabriela; Eggleston, Richard; Guerrero, Natalia; Henderson, Shawn; Lopez, Jeremy; Monroe, Jocelyn; Fisher, Peter

    2017-06-01

    The dark matter time projection chamber (DMTPC) is a direction-sensitive detector designed to measure the direction of recoiling F 19 and C 12 nuclei in low-pressure CF4 gas using optical and charge readout systems. In this paper, we employ measurements from two DMTPC detectors, with operating pressures of 30-60 torr, to develop and validate a model of the directional response and performance of such detectors as a function of recoil energy. Using our model as a benchmark, we formulate the necessary specifications for a scalable directional detector with sensitivity comparable to that of current-generation counting (nondirectional) experiments, which measure only recoil energy. Assuming the performance of existing DMTPC detectors, as well as current limits on the spin-dependent WIMP-nucleus cross section, we find that a 10-20 kg scale direction-sensitive detector is capable of correlating the measured direction of nuclear recoils with the predicted direction of incident dark matter particles and providing decisive (3 σ ) confirmation that a candidate signal from a nondirectional experiment was indeed induced by elastic scattering of dark matter particles off of target nuclei.

  4. Plastic scintillation detectors for precision Time-of-Flight measurements of relativistic heavy ions

    NASA Astrophysics Data System (ADS)

    Lin, Wen-Jian; Zhao, Jian-Wei; Sun, Bao-Hua; He, Liu-Chun; Lin, Wei-Ping; Liu, Chuan-Ye; Tanihata, Isao; Terashima, Satoru; Tian, Yi; Wang, Feng; Wang, Meng; Zhang, Guang-Xin; Zhang, Xue-Heng; Zhu, Li-Hua; Duan, Li-Min; Hu, Rong-Jiang; Liu, Zhong; Lu, Chen-Gui; Ren, Pei-Pei; Sheng, Li-Na; Sun, Zhi-Yu; Wang, Shi-Tao; Wang, Tao-Feng; Xu, Zhi-Guo; Zheng, Yong

    2017-06-01

    Plastic scintillation detectors for Time-of-Flight (TOF) measurements are almost essential for event-by-event identification of relativistic rare isotopes. In this work, a pair of plastic scintillation detectors of dimensions 50 × 50 × 3t mm3 and 80 × 100 × 3t mm3 have been set up at the External Target Facility (ETF), Institute of Modern Physics (IMP). Their time, energy and position responses are measured with the 18O primary beam at 400 MeV/nucleon. After off-line corrections for walk effect and position, the time resolutions of the two detectors are determined to be 27 ps (σ) and 36 ps (σ), respectively. Both detectors have nearly the same energy resolution of 3.1% (σ) and position resolution of about 3.4 mm (σ). The detectors have been used successfully in nuclear reaction cross section measurements, and will be be employed for upgrading the RIBLL2 beam line at IMP as well as for the high energy branch at HIAF. Supported by National Natural Science Foundation of China (11475014,11235002) and National Key Research and Development Program (2016YFA0400500)

  5. TOFFEE: a full custom amplifier-comparator chip for timing applications with silicon detectors

    NASA Astrophysics Data System (ADS)

    Cenna, F.; Cartiglia, N.; Di Francesco, A.; Olave, J.; Da Rocha Rolo, M.; Rivetti, A.; Silva, J. C.; Silva, R.; Varela, J.

    2017-03-01

    We report on the design of a full custom amplifier-comparator readout chip for silicon detectors with internal gain designed for precise timing applications. The ASIC has been developed in UMC 110 nm CMOS technology and is aimed to fulfill the CMS-TOTEM Precision Proton Spectrometer (CT-PPS) time resolution requirements (~ 30 ps per detector plane). It features LVDS outputs and the signal dynamic range matches the requirements of the High Precision TDC (HPTDC) system. The preliminary measurements results with a test board are included.

  6. Determination of the event collision time with the ALICE detector at the LHC

    NASA Astrophysics Data System (ADS)

    Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmad, S.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Alam, S. N.; Albuquerque, D. S. D.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; An, M.; Andrei, C.; Andrews, H. A.; Andronic, A.; Anguelov, V.; Anson, C.; Antičić, T.; Antinori, F.; Antonioli, P.; Anwar, R.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Arnaldi, R.; Arnold, O. W.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Balasubramanian, S.; Baldisseri, A.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Beltran, L. G. E.; Belyaev, V.; Bencedi, G.; Beole, S.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biro, G.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blair, J. T.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Boldizsár, L.; Bombara, M.; Bonora, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Botta, E.; Bourjau, C.; Braun-Munzinger, P.; Bregant, M.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buhler, P.; Buitron, S. A. I.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Cabala, J.; Caffarri, D.; Caines, H.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chauvin, A.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Cho, S.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Crkovská, J.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danisch, M. C.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; De, S.; De Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; De Falco, A.; De Gruttola, D.; De Marco, N.; De Pasquale, S.; De Souza, R. D.; Deisting, A.; Deloff, A.; Deplano, C.; Dhankher, P.; Di Bari, D.; Di Mauro, A.; Di Nezza, P.; Di Ruzza, B.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Drozhzhova, T.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Duggal, A. K.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Endress, E.; Engel, H.; Epple, E.; Erazmus, B.; Erhardt, F.; Espagnon, B.; Esumi, S.; Eulisse, G.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Francisco, A.; Frankenfeld, U.; Fronze, G. G.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gajdosova, K.; Gallio, M.; Galvan, C. D.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Garg, K.; Garg, P.; Gargiulo, C.; Gasik, P.; Gauger, E. F.; Gay Ducati, M. B.; Germain, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; Gonzalez, A. S.; Gonzalez, V.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Graczykowski, L. K.; Graham, K. L.; Greiner, L.; Grelli, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grion, N.; Gronefeld, J. M.; Grosse-Oetringhaus, J. F.; Grosso, R.; Gruber, L.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gunji, T.; Gupta, A.; Gupta, R.; Guzman, I. B.; Haake, R.; Hadjidakis, C.; Hamagaki, H.; Hamar, G.; Hamon, J. C.; Harris, J. W.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Hellbär, E.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Herrmann, F.; Hess, B. A.; Hetland, K. F.; Hillemanns, H.; Hippolyte, B.; Hladky, J.; Horak, D.; Hosokawa, R.; Hristov, P.; Hughes, C.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Inaba, M.; Ippolitov, M.; Irfan, M.; Isakov, V.; Islam, M. S.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacak, B.; Jacazio, N.; Jacobs, P. M.; Jadhav, M. B.; Jadlovska, S.; Jadlovsky, J.; Jahnke, C.; Jakubowska, M. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karayan, L.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Mohisin Khan, M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Khatun, A.; Khuntia, A.; Kileng, B.; Kim, D. W.; Kim, D. J.; Kim, D.; Kim, H.; Kim, J. S.; Kim, J.; Kim, M.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Klewin, S.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobdaj, C.; Kofarago, M.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kopcik, M.; Kour, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Koyithatta Meethaleveedu, G.; Králik, I.; Kravčáková, A.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kuhn, C.; Kuijer, P. G.; Kumar, A.; Kumar, J.; Kumar, L.; Kumar, S.; Kundu, S.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kushpil, S.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lapidus, K.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lazaridis, L.; Lea, R.; Leardini, L.; Lee, S.; Lehas, F.; Lehner, S.; Lehrbach, J.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Llope, W.; Lodato, D. F.; Loenne, P. I.; Loginov, V.; Loizides, C.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Lunardon, M.; Luparello, G.; Lupi, M.; Lutz, T. H.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manko, V.; Manso, F.; Manzari, V.; Mao, Y.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Mastroserio, A.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzilli, M.; Mazzoni, M. A.; Meddi, F.; Melikyan, Y.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Mhlanga, S.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Mischke, A.; Mishra, A. N.; Mishra, T.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Montes, E.; Moreira De Godoy, D. A.; Moreno, L. A. P.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Mulligan, J. D.; Munhoz, M. G.; Münning, K.; Munzer, R. H.; Murakami, H.; Murray, S.; Musa, L.; Musinsky, J.; Myers, C. J.; Naik, B.; Nair, R.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Natal da Luz, H.; Nattrass, C.; Navarro, S. R.; Nayak, K.; Nayak, R.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Negrao De Oliveira, R. A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Ohlson, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira Da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Orava, R.; Oravec, M.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pacik, V.; Pagano, D.; Pagano, P.; Paić, G.; Pal, S. K.; Palni, P.; Pan, J.; Pandey, A. K.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, J.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Patra, R. N.; Paul, B.; Pei, H.; Peitzmann, T.; Peng, X.; Pereira Da Costa, H.; Peresunko, D.; Perez Lezama, E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pimentel, L. O. D. L.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Poppenborg, H.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Pozdniakov, V.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Rami, F.; Rana, D. B.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Ratza, V.; Ravasenga, I.; Read, K. F.; Redlich, K.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rodríguez Cahuantzi, M.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Saarinen, S.; Sadhu, S.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Sandoval, A.; Sano, M.; Sarkar, D.; Sarkar, N.; Sarma, P.; Sas, M. H. P.; Scapparone, E.; Scarlassara, F.; Scharenberg, R. P.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schmidt, M.; Schukraft, J.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Šefčík, M.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Senyukov, S.; Serradilla, E.; Sett, P.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, A.; Sharma, M.; Sharma, M.; Sharma, N.; Sheikh, A. I.; Shigaki, K.; Shou, Q.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singhal, V.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; Sozzi, F.; Spiriti, E.; Sputowska, I.; Srivastava, B. K.; Stachel, J.; Stan, I.; Stankus, P.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Suljic, M.; Sultanov, R.; Šumbera, M.; Sumowidagdo, S.; Suzuki, K.; Swain, S.; Szabo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Tabassam, U.; Takahashi, J.; Tambave, G. J.; Tanaka, N.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thakur, D.; Thomas, D.; Tieulent, R.; Tikhonov, A.; Timmins, A. R.; Toia, A.; Tripathy, S.; Trogolo, S.; Trombetta, G.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Umaka, E. N.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vala, M.; Van Der Maarel, J.; Van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vázquez Doce, O.; Vechernin, V.; Veen, A. M.; Velure, A.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Vértesi, R.; Vickovic, L.; Vigolo, S.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Villatoro Tello, A.; Vinogradov, A.; Vinogradov, L.; Virgili, T.; Vislavicius, V.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Voscek, D.; Vranic, D.; Vrláková, J.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Weiser, D. F.; Wessels, J. P.; Westerhoff, U.; Whitehead, A. M.; Wiechula, J.; Wikne, J.; Wilk, G.; Wilkinson, J.; Willems, G. A.; Williams, M. C. S.; Windelband, B.; Winn, M.; Witt, W. E.; Yalcin, S.; Yang, P.; Yano, S.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yoon, J. H.; Yurchenko, V.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhang, C.; Zhang, Z.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zmeskal, J.

    2017-02-01

    Particle identification is an important feature of the ALICE detector at the LHC. In particular, for particle identification via the time-of-flight technique, the precise determination of the event collision time represents an important ingredient of the quality of the measurement. In this paper, the different methods used for such a measurement in ALICE by means of the T0 and the TOF detectors are reviewed. Efficiencies, resolution and the improvement of the particle identification separation power of the methods used are presented for the different LHC colliding systems (pp, p-Pb and Pb-Pb) during the first period of data taking of LHC (RUN 1).

  7. Electronic readout system for the Belle II imaging Time-Of-Propagation detector

    NASA Astrophysics Data System (ADS)

    Kotchetkov, Dmitri

    2017-07-01

    The imaging Time-Of-Propagation (iTOP) detector, constructed for the Belle II experiment at the SuperKEKB e+e- collider, is an 8192-channel high precision Cherenkov particle identification detector with timing resolution below 50 ps. To acquire data from the iTOP, a novel front-end electronic readout system was designed, built, and integrated. Switched-capacitor array application-specific integrated circuits are used to sample analog signals. Triggering, digitization, readout, and data transfer are controlled by Xilinx Zynq-7000 system on a chip devices.

  8. A high performance Time-of-Flight detector applied to isochronous mass measurement at CSRe

    NASA Astrophysics Data System (ADS)

    Mei, Bo; Tu, Xiaolin; Wang, Meng; Xu, Hushan; Mao, Ruishi; Hu, Zhengguo; Ma, Xinwen; Yuan, Youjin; Zhang, Xueying; Geng, Peng; Shuai, Peng; Zang, Yongdong; Tang, Shuwen; Ma, Peng; Lu, Wan; Yan, Xinshuai; Xia, Jiawen; Xiao, Guoqing; Guo, Zhongyan; Zhang, Hongbin; Yue, Ke

    2010-12-01

    A high performance Time-of-Flight detector has been designed and constructed for isochronous mass spectrometry at the experimental Cooler Storage Ring (CSRe). The detector has been successfully used in an experiment to measure the masses of the N≈ Z≈33 nuclides near the proton drip-line. Of particular interest is the mass of 65As. A maximum detection efficiency of 70% and a time resolution of 118±8 ps (FWHM) have been achieved in the experiment. The dependence of detection efficiency and signal average pulse height (APH) on atomic number Z has been studied. The potential of APH for Z identification has been discussed.

  9. Time delay and integration detectors using charge transfer devices

    NASA Astrophysics Data System (ADS)

    McCann, D. H.; White, M. H.; Turly, A. P.

    1981-07-01

    An imaging system comprises a multi-channel matrix array of CCD devices wherein a number of sensor cells (pixels) in each channel are subdivided and operated in discrete intercoupled groups of subarrays with a readout CCD shift register terminating each end of the channels. Clock voltages, applied to the subarrays, selectively cause charge signal flow in each subarray in either direction independent of the other subarrays. By selective application of four phase clock voltages, either one, two or all three of the sections subarray sections cause charge signal flow in one direction, while the remainder cause charge signal flow in the opposite direction. This creates a form of selective electronic exposure control which provides an effective variable time delay and integration of three, six or nine sensor cells or integration stages. The device is constructed on a semiconductor sustrate with a buried channel and is adapted for front surface imaging through transparent doped tin oxide gates.

  10. Time and volume dependence of dead space in healthy and surfactant-depleted rat lungs during spontaneous breathing and mechanical ventilation.

    PubMed

    Dassow, Constanze; Schwenninger, David; Runck, Hanna; Guttmann, Josef

    2013-11-01

    Volumetric capnography is a standard method to determine pulmonary dead space. Hereby, measured carbon dioxide (CO2) in exhaled gas volume is analyzed using the single-breath diagram for CO2. Unfortunately, most existing CO2 sensors do not work with the low tidal volumes found in small animals. Therefore, in this study, we developed a new mainstream capnograph designed for the utilization in small animals like rats. The sensor was used for determination of dead space volume in healthy and surfactant-depleted rats (n = 62) during spontaneous breathing (SB) and mechanical ventilation (MV) at three different tidal volumes: 5, 8, and 11 ml/kg. Absolute dead space and wasted ventilation (dead space volume in relation to tidal volume) were determined over a period of 1 h. Dead space increase and reversibility of the increase was investigated during MV with different tidal volumes and during SB. During SB, the dead space volume was 0.21 ± 0.14 ml and increased significantly at MV to 0.39 ± 0.03 ml at a tidal volume of 5 ml/kg and to 0.6 ± 0.08 ml at a tidal volume of 8 and 11 ml/kg. Dead space and wasted ventilation during MV increased with tidal volume. This increase was mostly reversible by switching back to SB. Surfactant depletion had no further influence on the dead space increase during MV, but impaired the reversibility of the dead space increase.

  11. Timing performance measurements of Si-PM-based LGSO phoswich detectors

    NASA Astrophysics Data System (ADS)

    Yamamoto, Seiichi; Kobayashi, Takahiro; Okumura, Satoshi; Yeom, Jung Yeol

    2016-06-01

    Since the timing resolution was significantly improved using silicon photomultipliers (Si-PMs) combined with fast scintillators, we expect that phoswich detectors will be used in future TOF-PET systems. However, no practical phoswich detector has been proposed for TOF-PET detectors. We conducted timing performance measurements of phoswich detectors comprised of two types of Ce-doped LGSO scintillators with different decay times coupled to Si-PMs and digitized the output signals using a high bandwidth digital oscilloscope. We prepared three types of LGSOs (LGSO-fast, LGSO-standard, and LGSO-slow) with different Ce concentrations. After measuring the decay time, the energy performance, and the timing performance of each LGSO, we conducted pulse shape analysis and timing resolution measurements for two versions of phoswich LGSOs: LGSO-standard/LGSO-fast and LGSO-slow/LGSO-fast combinations. The pulse shape spectra for a 10-mm-long crystal LGSO-slow/LGSO-fast combination showed good separation of the front and back crystals with a peak-to-valley ratio of 2.0. The timing resolutions for the 20-mm-long crystal LGSO-slow/LGSO-fast combination were ~300 ps FWHM. The timing resolutions for the phoswich LGSOs were slightly inferior than that measured with the individual LGSO fast, but the acquired timing resolution for the phoswich configuration, ~300 ps with a LGSO-slow/LGSO-fast combination, is adequate for TOF-PET systems. We conclude that LGSO phoswich detectors are promising for TOF-DOI-PET systems.

  12. Optical delay encoding for fast timing and detector signal multiplexing in PET

    PubMed Central

    Grant, Alexander M.; Levin, Craig S.

    2015-01-01

    Purpose: The large number of detector channels in modern positron emission tomography (PET) scanners poses a challenge in terms of readout electronics complexity. Multiplexing schemes are typically implemented to reduce the number of physical readout channels, but often result in performance degradation. Novel methods of multiplexing in PET must be developed to avoid this data degradation. The preservation of fast timing information is especially important for time-of-flight PET. Methods: A new multiplexing scheme based on encoding detector interaction events with a series of extremely fast overlapping optical pulses with precise delays is demonstrated in this work. Encoding events in this way potentially allows many detector channels to be simultaneously encoded onto a single optical fiber that is then read out by a single digitizer. A two channel silicon photomultiplier-based prototype utilizing this optical delay encoding technique along with dual threshold time-over-threshold is demonstrated. Results: The optical encoding and multiplexing prototype achieves a coincidence time resolution of 160 ps full width at half maximum (FWHM) and an energy resolution of 13.1% FWHM at 511 keV with 3 × 3 × 5 mm3 LYSO crystals. All interaction information for both detectors, including timing, energy, and channel identification, is encoded onto a single optical fiber with little degradation. Conclusions: Optical delay encoding and multiplexing technology could lead to time-of-flight PET scanners with fewer readout channels and simplified data acquisition systems. PMID:26233181

  13. Optical delay encoding for fast timing and detector signal multiplexing in PET

    SciTech Connect

    Grant, Alexander M.; Levin, Craig S.

    2015-08-15

    Purpose: The large number of detector channels in modern positron emission tomography (PET) scanners poses a challenge in terms of readout electronics complexity. Multiplexing schemes are typically implemented to reduce the number of physical readout channels, but often result in performance degradation. Novel methods of multiplexing in PET must be developed to avoid this data degradation. The preservation of fast timing information is especially important for time-of-flight PET. Methods: A new multiplexing scheme based on encoding detector interaction events with a series of extremely fast overlapping optical pulses with precise delays is demonstrated in this work. Encoding events in this way potentially allows many detector channels to be simultaneously encoded onto a single optical fiber that is then read out by a single digitizer. A two channel silicon photomultiplier-based prototype utilizing this optical delay encoding technique along with dual threshold time-over-threshold is demonstrated. Results: The optical encoding and multiplexing prototype achieves a coincidence time resolution of 160 ps full width at half maximum (FWHM) and an energy resolution of 13.1% FWHM at 511 keV with 3 × 3 × 5 mm{sup 3} LYSO crystals. All interaction information for both detectors, including timing, energy, and channel identification, is encoded onto a single optical fiber with little degradation. Conclusions: Optical delay encoding and multiplexing technology could lead to time-of-flight PET scanners with fewer readout channels and simplified data acquisition systems.

  14. Real-time violent action detector for elevator

    NASA Astrophysics Data System (ADS)

    Hayashi, Kentaro; Seki, Makito; Hirai, Takahide; Koichi, Takeuchi; Koichi, Sasakawa

    2005-12-01

    This paper presents a new critical event detection method simplified for an embedded appliance mounted on an elevator car. We first define that the critical event is unusual action such as violent action, counteraction, etc, and introduce the violent action degree(VAD). We use an optical flow based method to analyze the current state of the motion through an ITV(Industrial TeleVision) camera. After motion analysis, we calculate a normalized statistical value, which is the VAD. The statistical value is the multiple of the optical flow direction variance, the optical flow magnitude variance, and optical flow area. Our method calculates the statistical value variance and normalize it by the variance. At last we can detect critical event by thresholding the VAD. Then we implement this method on an embedded appliance. The appliance has an A/D converter with special designed frame buffer, a 400MIPS high performance micro processor, dynamic memory, and some flash ROM. Since we need to process the method 4Hz or faster to keep the detection performance, we shrink the images into 80 by 60 size, adopt the recursive correlation method, and analyze optical flows. The special designed frame buffer enables us for capturing sequencial two images at any time. After that we achieve about 8Hz processing performance on it. Our method detects 80% of critical events where at most 6% of false acception.

  15. Measurements of timing resolution of ultra-fast silicon detectors with the SAMPIC waveform digitizer

    NASA Astrophysics Data System (ADS)

    Breton, D.; De Cacqueray, V.; Delagnes, E.; Grabas, H.; Maalmi, J.; Minafra, N.; Royon, C.; Saimpert, M.

    2016-11-01

    The SAMpler for PICosecond time (SAMPIC) chip has been designed by a collaboration including CEA/IRFU/SEDI, Saclay and CNRS/LAL/SERDI, Orsay. It benefits from both the quick response of a time to digital converter and the versatility of a waveform digitizer to perform accurate timing measurements. Thanks to the sampled signals, smart algorithms making best use of the pulse shape can be used to improve time resolution. A software framework has been developed to analyse the SAMPIC output data and extract timing information by using either a constant fraction discriminator or a fast cross-correlation algorithm. SAMPIC timing capabilities together with the software framework have been tested using pulses generated by a signal generator or by a silicon detector illuminated by a pulsed infrared laser. Under these ideal experimental conditions, the SAMPIC chip has proven to be capable of timing resolutions down to 4 ps with synthesized signals and 40 ps with silicon detector signals.

  16. The MRPC-based ALICE time-of-flight detector: Status andperformance

    NASA Astrophysics Data System (ADS)

    Alici, A.; ALICE Collaboration

    2013-04-01

    The large time-of-flight (TOF) array is one of the main detectors devoted to charged hadron identification in the mid-rapidity region of the ALICE experiment at the LHC. It allows separation among pions, kaons and protons up to a few GeV/c, covering the full azimuthal angle and -0.9<η<0.9. The TOF exploits the innovative MRPC technology capable of an intrinsic time resolution better than 50 ps with an efficiency close to 100% and a large operational plateau; the full array consists of 1593 MRPCs covering a cylindrical surface of 141 m2. The TOF detector has been efficiently taking data since the first pp collisions recorded in ALICE in December 2009. In this report, the status of the TOF detector and the performance achieved for both pp and Pb-Pb collisions aredescribed.

  17. Recent technological developments on LGAD and iLGAD detectors for tracking and timing applications

    NASA Astrophysics Data System (ADS)

    Pellegrini, G.; Baselga, M.; Carulla, M.; Fadeyev, V.; Fernández-Martínez, P.; García, M. Fernández; Flores, D.; Galloway, Z.; Gallrapp, C.; Hidalgo, S.; Liang, Z.; Merlos, A.; Moll, M.; Quirion, D.; Sadrozinski, H.; Stricker, M.; Vila, I.

    2016-09-01

    This paper reports the latest technological development on the Low Gain Avalanche Detector (LGAD) and introduces a new architecture of these detectors called inverse-LGAD (iLGAD). Both approaches are based on the standard Avalanche Photo Diodes (APD) concept, commonly used in optical and X-ray detection applications, including an internal multiplication of the charge generated by radiation. The multiplication is inherent to the basic n++-p+-p structure, where the doping profile of the p+ layer is optimized to achieve high field and high impact ionization at the junction. The LGAD structures are optimized for applications such as tracking or timing detectors for high energy physics experiments or medical applications where time resolution lower than 30 ps is required. Detailed TCAD device simulations together with the electrical and charge collection measurements are presented through this work.

  18. Upgrades for the Precision Proton Spectrometer at the LHC: Precision timing and tracking detectors

    NASA Astrophysics Data System (ADS)

    Gallinaro, Michele

    2017-03-01

    The CMS-TOTEM Precision Proton Spectrometer (CT-PPS) is an approved project to add tracking and timing information at approximately ±210 m from the interaction point around the CMS detector. It is designed to operate at high luminosity with up to 50 interactions per 25 ns bunch crossing to perform measurements of e.g. the quartic gauge couplings and search for rare exclusive processes. During 2016, CT-PPS took data in normal high-luminosity proton-proton LHC collisions. In the coming years, high radiation doses and large multiple-vertex interactions will represent difficult challenges that resemble those of the high-luminosity LHC program. A coordinated effort of detector upgrades with the goal of reaching the physics goals while mitigating the degradation effects is under way. Upgrades to the tracking and timing detectors are discussed.

  19. MCP PMT with high time response and linear output current for neutron time-of-flight detectors

    NASA Astrophysics Data System (ADS)

    Dolotov, A. S.; Konovalov, P. I.; Nurtdinov, R. I.

    2016-09-01

    A microchannel plate (MCP) photomultiplier tube (PMT) with a subnanosecond time response and a high linear output current has been developed. PMT is designed for detection of weak pulses of radiation in UV-, visible and nearer-IR ranges and can be used in neutron time-of-flight (nTOF) detectors in experiments on laser compression of thermonuclear fuel. The results of measurements of MCP PMT main parameters are presented: photocathode spectral sensitivity, gain, maximum linear output current, and time response.

  20. Scintillating fiber detectors for precise time and position measurements read out with Si-PMs

    NASA Astrophysics Data System (ADS)

    Damyanova, A.; Bravar, A.

    2017-02-01

    We present the development and performance of compact scintillating fiber detectors read out with silicon photo-multipliers (Si-PMs). The compact size, fast response, and insensitivity to magnetic fields make these detectors suitable for a variety of applications where precise tracking and timing information is required. These detectors will be used with different particle beams (electrons, protons, heavy ions) at very high rates. In particular, we present the SciFi tracker/time of flight detector that is being developed for the Mu3e experiment at PSI (search for the lepton flavor violating decay μ → eee at very high rates). We also present the SciFi beam position detectors that will be employed in NA61 at CERN to track the incoming proton and heavy ion beam particles. We are considering different readout scenarios in which (a) each fiber is individually coupled to a single Si-PM photo-sensor and (b) fibers are arranged in columns and coupled to a Si-PM arrays.

  1. Design and robust tuning of control scheme based on the PD controller plus Disturbance Observer and low-order integrating first-order plus dead-time model.

    PubMed

    Matausek, M R; Ribić, A I

    2009-10-01

    This paper presents an effective design and robust tuning method for the control structure based on a series PD controller and a simple Disturbance Observer. All elements of the proposed controller are directly obtained from the low-order Integrating First-Order Plus Dead-Time (IFOPDT) model, used to approximate essential dynamic characteristics of lag-dominant stable, integrating and unstable plants. The structure of the proposed controller is an effective, easy to implement and tune, extension of the series PID controller. For the same robustness, a better disturbance rejection response is obtained by the proposed controller than that of the PID, by adjusting only two parameters with a clear meaning. A comparison with well-tuned PIDs, done by simulations, and the experimental results, obtained on a real thermal power plant, confirm that high performance and robustness are obtained, for dynamic characteristics common to industrial processes.

  2. Enhanced ν-optical time domain reflectometry using gigahertz sinusoidally gated InGaAs/InP single-photon avalanche detector

    NASA Astrophysics Data System (ADS)

    Zhang, Xuping; Shi, Yuanlei; Shan, Yuanyuan; Sun, Zhenhong; Qiao, Weiyan; Zhang, Yixin

    2016-09-01

    Optical time domain reflectometry (OTDR) is one of the most successful diagnostic tools for nondestructive attenuation measurement of a fiber link. To achieve better sensitivity, spatial resolution, and avoid dead-zone in conversional OTDR, a single-photon detector has been introduced to form the photon-counting OTDR (ν-OTDR). We have proposed a ν-OTDR system using a gigahertz sinusoidally gated InGaAs/InP single-photon avalanche detector (SPAD). Benefiting from the superior performance of a sinusoidal gated SPAD on dark count probability, gating frequency, and gate duration, our ν-OTDR system has achieved a dynamic range (DR) of 33.4 dB with 1 μs probe pulse width after an equivalent measurement time of 51 s. This obtainable DR corresponds to a sensing length over 150 km. Our system has also obtained a spatial resolution of 5 cm at the end of a 5-km standard single-mode fiber. By employing a sinusoidal gating technique, we have improved the ν-OTDR spatial resolution and significantly reduced the measurement time.

  3. Time-over-threshold for pulse shape discrimination in a time-of-flight phoswich PET detector.

    PubMed

    Chang, Chen-Ming; Cates, Joshua W; Levin, Craig S

    2017-01-07

    It is well known that a PET detector capable of measuring both photon time-of-flight (TOF) and depth-of-interaction (DOI) improves the image quality and accuracy. Phoswich designs have been realized in PET detectors to measure DOI for more than a decade. However, PET detectors based on phoswich designs put great demand on the readout circuits, which have to differentiate the pulse shape produced by different crystal layers. A simple pulse shape discrimination approach is required to realize the phoswich designs in a clinical PET scanner, which consists of thousands of scintillation crystal elements. In this work, we studied time-over-threshold (ToT) as a pulse shape parameter for DOI. The energy, timing and DOI performance were evaluated for a phoswich detector design comprising [Formula: see text] mm LYSO:Ce crystal optically coupled to [Formula: see text] mm calcium co-doped LSO:Ce,Ca(0.4%) crystal read out by a silicon photomultiplier (SiPM). A DOI accuracy of 97.2% has been achieved for photopeak events using the proposed time-over-threshold (ToT) processing. The energy resolution without correction for SiPM non-linearity was [Formula: see text]% and [Formula: see text]% FWHM at 511 keV for LYSO and LSO crystal layers, respectively. The coincidence time resolution for photopeak events ranges from 164.6 ps to 183.1 ps FWHM, depending on the layer combinations. The coincidence time resolution for inter-crystal scatter events ranges from 214.6 ps to 418.3 ps FWHM, depending on the energy windows applied. These results show great promises of using ToT for pulse shape discrimination in a TOF phoswich detector since a ToT measurement can be easily implemented in readout electronics.

  4. Time of flight experimental studies of CdZnTe radiation detectors

    NASA Astrophysics Data System (ADS)

    Erickson, J. C.; Yao, H. W.; James, R. B.; Hermon, H.; Greaves, M.

    2000-06-01

    A time of flight technique was used to study the carrier trapping time, τ, and mobility, μ, in CdZnTe (CZT) and CdTe radiation detectors. Carriers were generated near the surface of the detector by a nitrogen-pumped pulsed dye laser with wavelength ˜500 nm. Signals from generated electrons or holes were measured by a fast oscilloscope and analyzed to determine the trapping time and mobility of carriers. Electron mobility was observed to change with temperature from 1200 cm2/Vs to 2400 cm2/Vs between 293 K and 138 K, respectively. Electron mobilities were observed between 900 cm2/Vs and 1350 cm2/Vs at room temperature for various CZT detectors. Electron mobilities in various CdTe detectors at room temperature were observed between 740 cm2/Vs and 1260 cm2/Vs. Average electron mobility was calculated to be 1120 cm2/Vs and 945 cm2/Vs for CZT and CdTe, respectively. Hole mobilities in both CZT and CdTe were found to vary between 27 cm2/Vs and 66 cm2/Vs. Electron trapping times in CZT at room temperature varied from 1.60 µs to 4.18 µs with an average value of about 2.5 µs. Electron trapping time in CdTe at room temperature varied between 1.7 µs and 4.15 µs with an average value of about 3.1 µs.

  5. Novel real-time alignment and calibration of the LHCb detector and its performance

    NASA Astrophysics Data System (ADS)

    Borghi, S.

    2017-02-01

    The LHCb detector is a forward spectrometer at the LHC, designed to perform high precision studies of B and D hadrons. In Run II of the LHC, a new scheme for the software trigger at LHCb allows splitting the triggering of events in two stages, giving room to perform the detector alignment and calibration in real time. In the novel detector alignment and calibration strategy for Run II, data collected at the start of the fill are processed in a few minutes and used to update the alignment constants, while the calibration constants are evaluated for each run. This allows identical constants to be used in the online and offline reconstruction, thus improving the correlation between triggered and offline selected events. The required computing time constraints are met thanks to a new dedicated framework using the multi-core farm infrastructure for the trigger. The larger timing budget, available in the trigger, allows us to perform the same track reconstruction online and offline. This enables LHCb to achieve the best reconstruction performance already in the trigger, and allows physics analyses to be performed directly on the data produced by the trigger reconstruction. The novel real-time processing strategy at LHCb is discussed from both the technical and operational point of view. The overall performance of the LHCb detector on the data of Run II is presented as well.

  6. MULTICHANNEL ENERGY AND TIMING MEASUREMENTS WITH THE PEAK DETECTOR/DERANDOMIZER ASIC.

    SciTech Connect

    O'CONNOR,P.; DE GERONIMO,G.; GROSHOLZ,J.; KANDASAMY,A.; JUNNARKAR,S.; FRIED,J.

    2004-10-16

    The Peak Detector/Derandomizer ASIC (PDD) provides threshold discrimination, peak detection, time-to-amplitude conversion, analog memory, sparsification, and multiplexing for 32 channels of analog pulse data. In this work the spectroscopic capabilities of the chip (high resolution and high rate) are demonstrated along with correlated measurements of pulse risetime. Imaging and coincidence detection using the PDD chip will also be illustrated.

  7. WE-AB-BRB-09: Real Time In Vivo Scintillating Fiber Array Detector for Medical LINACS

    SciTech Connect

    Knewtson, T; Pokhrel, S; Hernandez-Morales, D; Loyalka, S; Rangaraj, D; Izaguirre, E; Price, S

    2015-06-15

    Purpose: An in vivo transmission scintillation fiber detector was developed to monitor patient treatment in real time for the enhancement of patient safety and treatment accuracy. The detector system is capable of monitoring each pulse from a medical LINAC during treatment to determine the dose delivered as treatment progresses. Methods: The detector system consists of 60 parallel scintillating fibers coupled to fast data processing optoelectronics that can monitor the beam fluence in real time. Each 2.5mm{sup 2} square fiber is aligned with an MLC leaf pair and is long enough to capture a 40cm field. The fibers are embedded within a water equivalent polymer substrate that is secured in the LINAC accessory tray. The fibers are coupled to high speed photosensors and front end amplifiers that filter noise and pass each pulse to a high speed analog-to-digital converter. The system components are capable of detecting pulse repetition times shorter than what is delivered by a medical LINAC to ensure true real time data acquisition. Results: The system was able to capture and record the signal from each linac pulse and display the information in real time with no pulse pile up. It was found that the fiber array attenuates 2.65% of the beam which can easily be compensated for in treatment planning. The fibers responded linearly with dose, are independent of clinical beam energies, and are independent of dose rate. Calibration of the system was performed as a function of beam energy, beam size, dose rate, and monitor units to optimize beam fluence error detection. Conclusion: The detector system presented provides true real time in vivo beam monitoring to enhance patient safety and treatment delivery accuracy. Furthermore, the detector can be used for current patient specific QA.

  8. Timing resolution of scintillation-detector systems: a Monte Carlo analysis

    PubMed Central

    Choong, Woon-Seng

    2010-01-01

    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 a 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 2-threshold or 3-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 decreasing

  9. Iterative Bayesian Estimation of Travel Times on Urban Arterials: Fusing Loop Detector and Probe Vehicle Data

    PubMed Central

    Cui, Meng-Ying; Cao, Peng; Wang, Jiang-Bo

    2016-01-01

    On urban arterials, travel time estimation is challenging especially from various data sources. Typically, fusing loop detector data and probe vehicle data to estimate travel time is a troublesome issue while considering the data issue of uncertain, imprecise and even conflicting. In this paper, we propose an improved data fusing methodology for link travel time estimation. Link travel times are simultaneously pre-estimated using loop detector data and probe vehicle data, based on which Bayesian fusion is then applied to fuse the estimated travel times. Next, Iterative Bayesian estimation is proposed to improve Bayesian fusion by incorporating two strategies: 1) substitution strategy which replaces the lower accurate travel time estimation from one sensor with the current fused travel time; and 2) specially-designed conditions for convergence which restrict the estimated travel time in a reasonable range. The estimation results show that, the proposed method outperforms probe vehicle data based method, loop detector based method and single Bayesian fusion, and the mean absolute percentage error is reduced to 4.8%. Additionally, iterative Bayesian estimation performs better for lighter traffic flows when the variability of travel time is practically higher than other periods. PMID:27362654

  10. Iterative Bayesian Estimation of Travel Times on Urban Arterials: Fusing Loop Detector and Probe Vehicle Data.

    PubMed

    Liu, Kai; Cui, Meng-Ying; Cao, Peng; Wang, Jiang-Bo

    2016-01-01

    On urban arterials, travel time estimation is challenging especially from various data sources. Typically, fusing loop detector data and probe vehicle data to estimate travel time is a troublesome issue while considering the data issue of uncertain, imprecise and even conflicting. In this paper, we propose an improved data fusing methodology for link travel time estimation. Link travel times are simultaneously pre-estimated using loop detector data and probe vehicle data, based on which Bayesian fusion is then applied to fuse the estimated travel times. Next, Iterative Bayesian estimation is proposed to improve Bayesian fusion by incorporating two strategies: 1) substitution strategy which replaces the lower accurate travel time estimation from one sensor with the current fused travel time; and 2) specially-designed conditions for convergence which restrict the estimated travel time in a reasonable range. The estimation results show that, the proposed method outperforms probe vehicle data based method, loop detector based method and single Bayesian fusion, and the mean absolute percentage error is reduced to 4.8%. Additionally, iterative Bayesian estimation performs better for lighter traffic flows when the variability of travel time is practically higher than other periods.

  11. Calibration of a time-resolved hard-x-ray detector using radioactive sources

    SciTech Connect

    Stoeckl, C. Theobald, W.; Regan, S. P.; Romanofsky, M. H.

    2016-11-15

    A four-channel, time-resolved, hard x-ray detector (HXRD) has been operating at the Laboratory for Laser Energetics for more than a decade. The slope temperature of the hot-electron population in direct-drive inertial confinement fusion experiments is inferred by recording the hard x-ray radiation generated in the interaction of the electrons with the target. Measuring the energy deposited by hot electrons requires an absolute calibration of the hard x-ray detector. A novel method to obtain an absolute calibration of the HXRD using single photons from radioactive sources was developed, which uses a thermoelectrically cooled, low-noise, charge-sensitive amplifier.

  12. Calibration of a time-resolved hard-x-ray detector using radioactive sources

    NASA Astrophysics Data System (ADS)

    Stoeckl, C.; Theobald, W.; Regan, S. P.; Romanofsky, M. H.

    2016-11-01

    A four-channel, time-resolved, hard x-ray detector (HXRD) has been operating at the Laboratory for Laser Energetics for more than a decade. The slope temperature of the hot-electron population in direct-drive inertial confinement fusion experiments is inferred by recording the hard x-ray radiation generated in the interaction of the electrons with the target. Measuring the energy deposited by hot electrons requires an absolute calibration of the hard x-ray detector. A novel method to obtain an absolute calibration of the HXRD using single photons from radioactive sources was developed, which uses a thermoelectrically cooled, low-noise, charge-sensitive amplifier.

  13. Real-time control of the beam attenuation with XPAD hybrid pixel detector

    NASA Astrophysics Data System (ADS)

    Dawiec, A.; Garreau, Y.; Bisou, J.; Hustache, S.; Kanoute, B.; Picca, F.; Renaud, G.; Coati, A.

    2016-12-01

    In order to fully benefit from a beam produced by modern synchrotron light sources, characterised by a wide and continuous energy spectrum, high brightness and a very high intensity, advancement in detector technology has been made over the last decades. However, one of the main limitations of the state-of-the-art counting hybrid pixel detectors is the maximum count-rate that is very often few orders of magnitudes lower than of the incident, reflected or diffracted beam flux. Therefore, direct beam attenuation is mandatory in order to perform the measurements according to the detector's characteristics. In this work we present a major upgrade of a fast attenuation system developed at Synchrotron SOLEIL, which allows for a dynamical change of the beam attenuation as a function of the photon flux received by XPAD S140 photon counting detector. The system performs a cyclic real-time estimation of the flux received by every pixel during acquisition of an image and searches for clusters of at least two pixels that exceed user defined levels of counts/s. The beam attenuation is immediately and automatically changed in order to guarantee that the detector will always operate in its linear range even during a long continuous scan, by acting on the direct attenuators.

  14. A gas ionisation detector in the axial (Bragg) geometry used for the time-of-flight elastic recoil detection analysis

    SciTech Connect

    Siketić, Zdravko; Skukan, Natko; Bogdanović Radović, Iva

    2015-08-15

    In this paper, time-of-flight elastic recoil detection analysis spectrometer with a newly constructed gas ionization detector for energy detection is presented. The detector is designed in the axial (Bragg) geometry with a 3 × 3 array of 50 nm thick Si{sub 3}N{sub 4} membranes as an entrance window. 40 mbar isobutane gas was sufficient to stop a 30 MeV primary iodine beam as well as all recoils in the detector volume. Spectrometer and detector performances were determined showing significant improvement in the mass and energy resolution, respectively, comparing to the spectrometer with a standard silicon particle detector for an energy measurement.

  15. A gas ionisation detector in the axial (Bragg) geometry used for the time-of-flight elastic recoil detection analysis.

    PubMed

    Siketić, Zdravko; Skukan, Natko; Bogdanović Radović, Iva

    2015-08-01

    In this paper, time-of-flight elastic recoil detection analysis spectrometer with a newly constructed gas ionization detector for energy detection is presented. The detector is designed in the axial (Bragg) geometry with a 3 × 3 array of 50 nm thick Si3N4 membranes as an entrance window. 40 mbar isobutane gas was sufficient to stop a 30 MeV primary iodine beam as well as all recoils in the detector volume. Spectrometer and detector performances were determined showing significant improvement in the mass and energy resolution, respectively, comparing to the spectrometer with a standard silicon particle detector for an energy measurement.

  16. Optimizing the timing resolution of SiPM sensors for use in TOF-PET detectors

    NASA Astrophysics Data System (ADS)

    Vinke, R.; Löhner, H.; Schaart, D. R.; van Dam, H. T.; Seifert, S.; Beekman, F. J.; Dendooven, P.

    2009-10-01

    We have investigated the timing performance of Hamamatsu Multi-Pixel Photon Counter (MPPC) photosensors in light of their use in time-of-flight (TOF) positron emission tomography detectors. Measurements using picosecond laser pulses show a single photo-electron root-mean-square (RMS) timing resolution down to about 100 ps. In coincidences of 511 keV photons detected with an LYSO crystal coupled to a MPPC and a BaF 2 detector, an optimum FWHM timing resolution of 600 ps was obtained with leading edge time pickoff at the 1-1.5 photo-electron level. By optimizing the LYSO/MPPC coupling, this can be improved by a factor of 2. We further conclude that the use of stored digitized pulses allows great flexibility and efficiency in developing data analysis algorithms.

  17. Energy and Timing Measurement with Time-Based Detector Readout for PET Applications: Principle and Validation with Discrete Circuit Components

    PubMed Central

    Sun, Xishan; Lan, Allan K.; Bircher, Chad; Deng, Zhi; Liu, Yinong; Shao, Yiping

    2011-01-01

    A new signal processing method for PET application has been developed, with discrete circuit components to measure energy and timing of a gamma interaction based solely on digital timing processing without using an amplitude-to-digital convertor (ADC) or a constant fraction discriminator (CFD). A single channel discrete component time-based readout (TBR) circuit was implemented in a PC board. Initial circuit functionality and performance evaluations have been conducted. Accuracy and linearity of signal amplitude measurement were excellent, as measured with test pulses. The measured timing accuracy from test pulses reached to less than 300 ps, a value limited mainly by the timing jitter of the prototype electronics circuit. Both suitable energy and coincidence timing resolutions (~18% and ~1.0 ns) have been achieved with 3 × 3 × 20 mm3 LYSO scintillator and photomultiplier tube-based detectors. With its relatively simple circuit and low cost, TBR is expected to be a suitable front-end signal readout electronics for compact PET or other radiation detectors requiring the reading of a large number of detector channels and demanding high performance for energy and timing measurement. PMID:21743761

  18. Energy and Timing Measurement with Time-Based Detector Readout for PET Applications: Principle and Validation with Discrete Circuit Components.

    PubMed

    Sun, Xishan; Lan, Allan K; Bircher, Chad; Deng, Zhi; Liu, Yinong; Shao, Yiping

    2011-06-11

    A new signal processing method for PET application has been developed, with discrete circuit components to measure energy and timing of a gamma interaction based solely on digital timing processing without using an amplitude-to-digital convertor (ADC) or a constant fraction discriminator (CFD). A single channel discrete component time-based readout (TBR) circuit was implemented in a PC board. Initial circuit functionality and performance evaluations have been conducted. Accuracy and linearity of signal amplitude measurement were excellent, as measured with test pulses. The measured timing accuracy from test pulses reached to less than 300 ps, a value limited mainly by the timing jitter of the prototype electronics circuit. Both suitable energy and coincidence timing resolutions (~18% and ~1.0 ns) have been achieved with 3 × 3 × 20 mm(3) LYSO scintillator and photomultiplier tube-based detectors. With its relatively simple circuit and low cost, TBR is expected to be a suitable front-end signal readout electronics for compact PET or other radiation detectors requiring the reading of a large number of detector channels and demanding high performance for energy and timing measurement.

  19. Real-time human identification using a pyroelectric infrared detector array and hidden Markov models.

    PubMed

    Fang, Jian-Shuen; Hao, Qi; Brady, David J; Guenther, Bob D; Hsu, Ken Y

    2006-07-24

    This paper proposes a real-time human identification system using a pyroelectric infrared (PIR) detector array and hidden Markov models (HMMs). A PIR detector array with masked Fresnel lens arrays is used to generate digital sequential data that can represent a human motion feature. HMMs are trained to statistically model the motion features of individuals through an expectation-maximization (EM) learning process. Human subjects are recognized by evaluating a set of new feature data against the trained HMMs using the maximum-likelihood (ML) criterion. We have developed a prototype system to verify the proposed method. Sensor modules with different numbers of detectors and different sampling masks were tested to maximize the identification capability of the sensor system.

  20. Note: Development of real-time epithermal neutron detector for boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Tanaka, H.; Sakurai, Y.; Takata, T.; Watanabe, T.; Kawabata, S.; Suzuki, M.; Masunaga, S.-I.; Taki, K.; Akabori, K.; Watanabe, K.; Ono, K.

    2017-05-01

    The real-time detection of epithermal neutrons forms an important aspect of boron neutron capture therapy. In this context, we developed an epithermal neutron detector based on the combination of a small Eu:LiCaAlF6 scintillator and a quartz fiber in order to fulfill the irradiation-field requirements for boron neutron capture therapy. The irradiation test is performed with the use of a reactor-based neutron source. The thermal and epithermal neutron sensitivities of our epithermal neutron detector are estimated to be 9.52 × 10-8 ± 1.59 × 10-8 cm2 and 1.20 × 10-6 cm2 ± 8.96 × 10-9 cm2, respectively. We also subject the developed epithermal neutron detector to actual irradiation fields, and we confirm that the epithermal neutron flux can be measured in realtime.

  1. Discrimination of viable and dead Vibrio vulnificus after refrigerated and frozen storage using EMA, sodium deoxycholate and real-time PCR.

    PubMed

    Lee, Jung-Lim; Levin, Robert E

    2009-11-01

    The effect of refrigerated and frozen storage on the viability of Vibrio vulnificus was evaluated using cell suspensions (1x10(8) CFU/ml). Ethidium bromide monoazide (EMA) was utilized to selectively allow real-time (Rti) PCR amplification of target DNA from viable but not dead cells. Bacterial survivors from the EMA Rti-PCR were evaluated by comparison with the plate count assay following different temperature exposures (-20 and 4 degrees C) every 24 h for 72 h. The log CFU values from the EMA Rti-PCR assays were erroneously higher than that from plate counts. DNA amplification was not completely suppressed by EMA treatment of low temperature destroyed cells suggesting that membrane damage was not sufficient to allow effective EMA penetration into the cells. The optimal concentration of sodium deoxycholate (SD) was also determined to enhance discrimination of viable and dead cells following exposure of cells to low temperatures. The use of 0.01% or less of SD did not inhibit the Rti-PCR amplification derived from viable bacterial cells. A rapid decrease of the log CFU was observed with cell suspensions subjected to frozen storage and a slow decline in the log CFU occurred at 4 degrees C. The combination of SD and EMA treatments applied to cells of V. vulnificus held at -20 degrees C and 4 degrees C resulted in a high level of correlation between the log of CFU (plate counts) and the log of the number of viable cells determined from SD+EMA Rti-PCR.

  2. Method to quantify live and dead cells in multi-species oral biofilm by real-time PCR with propidium monoazide

    PubMed Central

    2013-01-01

    Real-time PCR (qPCR) is a widely used technique in analysing environmental and clinical microbiological samples. However, its main limitation was its inability to discriminate between live and dead cells. Recently, propidium monoazide (PMA) together with qPCR has been used to overcome this problem, with good results for different bacterial species in different types of samples. Our objective was to implement this technique for analysing mortality in multi-species oral biofilms formed in vitro with five oral bacteria: Streptococcus oralis, Streptococcus gordonii, Veillonella parvula, Fusobacterium nucleatum and Prevotella intermedia. We also tested its effectiveness on biofilms treated with an antiseptic solution containing 0.07% w/w cetylpyridinium chloride (CPC). Standardisation of the qPCR-PMA method was performed on pure, heat-killed planktonic cultures of each species, detecting mortality higher than 4 log in S. oralis, S. gordonii and F. nucleatum and higher than 2 for V. parvula and P. intermedia. We obtained similar results for all species when using CPC. When we analysed biofilms with qPCR-PMA, we found that the mortality in the non-CPC treated multi-species biofilms was lower than 1 log for all species. After treatment with CPC, the viability reduction was higher than 4 log in S. oralis and S. gordonii, higher than 3 log in F. nucleatum and P. intermedia and approximately 2 in V. parvula. In short, we standardised the conditions for using qPCR-PMA in 5 oral bacterial species and proved its usefulness for quantification of live and dead cells in multi-species oral biofilms formed in vitro, after use of an antiseptic. PMID:23289803

  3. Timing calibration and synchronization of surface and fluorescence detectors of the Pierre Auger Observatory

    SciTech Connect

    Allison, P.; Bellido, J.; Bertou, Xavier; Covault, C.E.; Fick, B.E.; Gemmeke, H.; Kleifges, M.; Mostafa, M.; Menshikov, A.; Meyer, F.; Pryke, C.; Sommers, P.; Vanderpan, E.; Vernotte, F.; Wiencke, L.

    2005-08-01

    Reconstruction of cosmic ray arrival directions for Surface Detectors (SD) and Fluorescence Detectors (FD) of the Pierre Auger Observatory requires accurate timing (25 nanoseconds or better) between measurements at individual detectors and instrument triggers. Timing systems for both SD and FD are based on Motorola Oncore UT+ GPS receivers installed into custom-built time-tagging circuits that are calibrated in the laboratory to a statistical precision of better than 15 ns. We describe timing calibration and synchronization methods applied in the field for both the SD and the FD systems in four areas: (1) checks of timing offsets within the SD using co-located station pairs and timing residuals on reconstructed showers, (2) calibration within the FD using a custom-build LED calibration system, (3) calibration between SD and FD using laser signals fed simultaneously into an SD station and across the FD via the Central Laser Facility (CLF), and (4) studies of synchronization between FD and SD through the analysis of events detected by both systems, called hybrid events. These hybrid events allow for a much more accurate reconstruction of the shower and for relatively tight constraints on timing calibration offsets. We demonstrate that statistical and systematic timing uncertainties have no significant impact on the event reconstruction.

  4. Design and Fabrication of TES Detector Modules for the TIME-Pilot [CII] Intensity Mapping Experiment

    NASA Astrophysics Data System (ADS)

    Hunacek, J.; Bock, J.; Bradford, C. M.; Bumble, B.; Chang, T.-C.; Cheng, Y.-T.; Cooray, A.; Crites, A.; Hailey-Dunsheath, S.; Gong, Y.; Kenyon, M.; Koch, P.; Li, C.-T.; O'Brient, R.; Shirokoff, E.; Shiu, C.; Staniszewski, Z.; Uzgil, B.; Zemcov, M.

    2016-08-01

    We are developing a series of close-packed modular detector arrays for TIME-Pilot, a new mm-wavelength grating spectrometer array that will map the intensity fluctuations of the redshifted 157.7 \\upmu m emission line of singly ionized carbon ([CII]) from redshift z ˜ 5 to 9. TIME-Pilot's two banks of 16 parallel-plate waveguide spectrometers (one bank per polarization) will have a spectral range of 183-326 GHz and a resolving power of R ˜ 100. The spectrometers use a curved diffraction grating to disperse and focus the light on a series of output arcs, each sampled by 60 transition edge sensor (TES) bolometers with gold micro-mesh absorbers. These low-noise detectors will be operated from a 250 mK base temperature and are designed to have a background-limited NEP of {˜ }10^{-17} mathrm {W}/mathrm {Hz}^{1/2}. This proceeding presents an overview of the detector design in the context of the TIME-Pilot instrument. Additionally, a prototype detector module produced at the Microdevices Laboratory at JPL is shown.

  5. Optimization of a LSO-Based Detector Module for Time-of-Flight PET

    PubMed Central

    Moses, W. W.; Janecek, M.; Spurrier, M. A.; Szupryczynski, P.; Choong, W.-S.; Melcher, C. L.; Andreaco, M.

    2011-01-01

    We have explored methods for optimizing the timing resolution of an LSO-based detector module for a single-ring, “demonstration” time-of-flight PET camera. By maximizing the area that couples the scintillator to the PMT and minimizing the average path length that the scintillation photons travel, a single detector timing resolution of 218 ps fwhm is measured, which is considerably better than the ~385 ps fwhm obtained by commercial LSO or LYSO TOF detector modules. We explored different surface treatments (saw-cut, mechanically polished, and chemically etched) and reflector materials (Teflon tape, ESR, Lumirror, Melinex, white epoxy, and white paint), and found that for our geometry, a chemically etched surface had 5% better timing resolution than the saw-cut or mechanically polished surfaces, and while there was little dependence on the timing resolution between the various reflectors, white paint and white epoxy were a few percent better. Adding co-dopants to LSO shortened the decay time from 40 ns to ~30 ns but maintained the same or higher total light output. This increased the initial photoelectron rate and so improved the timing resolution by 15%. Using photomultiplier tubes with higher quantum efficiency (blue sensitivity index of 13.5 rather than 12) improved the timing resolution by an additional 5%. By choosing the optimum surface treatment (chemically etched), reflector (white paint), LSO composition (co-doped), and PMT (13.5 blue sensitivity index), the coincidence timing resolution of our detector module was reduced from 309 ps to 220 ps fwhm. PMID:21738262

  6. Optimizing the response time of Ni-based resistive temperature detectors

    NASA Astrophysics Data System (ADS)

    Kim, Deok Su; Choi, Kyo Sang; Yang, Hee Jun; Ryu, Min Soo; Chae, Ji Sung; Chang, Sung Pil

    2015-04-01

    Resistive temperature detectors (RTDs) are widely used to monitor and control the temperature of work environments due to their higher sensitivity, excellent reliability and stability, and very linear output signal compared to other types of temperature detectors. However, RTDs have some shortcomings, including a slow response time. A nickel-based RTDs were designed, fabricated, and characterized in order to achieve faster response times. We used micromachining processes to analyze devices with different resistor thicknesses, distances between resistor lines, and resistor line widths. The response times of the RTDs were measured to be between 7.5104 and 23.4583 s. From these measurement data, we can conclude that thinner RTDs with larger surface areas show improved response times.

  7. Performance study of the fast timing Cherenkov detector based on a microchannel plate PMT

    NASA Astrophysics Data System (ADS)

    Finogeev, D. A.; Grigoriev, V. A.; Kaplin, V. A.; Karavichev, O. V.; Karavicheva, T. L.; Konevskikh, A. S.; Kurepin, A. B.; Kurepin, A. N.; Loginov, V. A.; Mayevskaya, A. I.; Melikyan, Yu A.; Morozov, I. V.; Serebryakov, D. V.; Shabanov, A. I.; Slupecki, M.; Tikhonov, A. A.; Trzaska, W. H.

    2017-01-01

    Prototype of the fast timing Cherenkov detector, applicable in high-energy collider experiments, has been developed basing on the modified Planacon XP85012 MCP-PMT and fused silica radiators. We present the reasons and description of the MCP-PMT modification, timing and amplitude characteristics of the prototype including the summary of the detector’s response on particle hits at oblique angles and MCP-PMT performance at high illumination rates.

  8. Nanosecond-level time synchronization of autonomous radio detector stations for extensive air showers

    NASA Astrophysics Data System (ADS)

    The Pierre Auger Collaboration

    2016-01-01

    To exploit the full potential of radio measurements of cosmic-ray air showers at MHz frequencies, a detector timing synchronization within 1 ns is needed. Large distributed radio detector arrays such as the Auger Engineering Radio Array (AERA) rely on timing via the Global Positioning System (GPS) for the synchronization of individual detector station clocks. Unfortunately, GPS timing is expected to have an accuracy no better than about 5 ns. In practice, in particular in AERA, the GPS clocks exhibit drifts on the order of tens of ns. We developed a technique to correct for the GPS drifts, and an independent method is used to cross-check that indeed we reach a nanosecond-scale timing accuracy by this correction. First, we operate a ``beacon transmitter'' which emits defined sine waves detected by AERA antennas recorded within the physics data. The relative phasing of these sine waves can be used to correct for GPS clock drifts. In addition to this, we observe radio pulses emitted by commercial airplanes, the position of which we determine in real time from Automatic Dependent Surveillance Broadcasts intercepted with a software-defined radio. From the known source location and the measured arrival times of the pulses we determine relative timing offsets between radio detector stations. We demonstrate with a combined analysis that the two methods give a consistent timing calibration with an accuracy of 2 ns or better. Consequently, the beacon method alone can be used in the future to continuously determine and correct for GPS clock drifts in each individual event measured by AERA.

  9. Nanosecond-level time synchronization of autonomous radio detector stations for extensive air showers

    DOE PAGES

    Aab, Alexander

    2016-01-29

    To exploit the full potential of radio measurements of cosmic-ray air showers at MHz frequencies, a detector timing synchronization within 1 ns is needed. Large distributed radio detector arrays such as the Auger Engineering Radio Array (AERA) rely on timing via the Global Positioning System (GPS) for the synchronization of individual detector station clocks. Unfortunately, GPS timing is expected to have an accuracy no better than about 5 ns. In practice, in particular in AERA, the GPS clocks exhibit drifts on the order of tens of ns. We developed a technique to correct for the GPS drifts, and an independentmore » method used for cross-checks that indeed we reach nanosecond-scale timing accuracy by this correction. First, we operate a “beacon transmitter” which emits defined sine waves detected by AERA antennas recorded within the physics data. The relative phasing of these sine waves can be used to correct for GPS clock drifts. In addition to this, we observe radio pulses emitted by commercial airplanes, the position of which we determine in real time from Automatic Dependent Surveillance Broadcasts intercepted with a software-defined radio. From the known source location and the measured arrival times of the pulses we determine relative timing offsets between radio detector stations. We demonstrate with a combined analysis that the two methods give a consistent timing calibration with an accuracy of 2 ns or better. Consequently, the beacon method alone can be used in the future to continuously determine and correct for GPS clock drifts in each individual event measured by AERA.« less

  10. Nanosecond-level time synchronization of autonomous radio detector stations for extensive air showers

    SciTech Connect

    Aab, Alexander

    2016-01-29

    To exploit the full potential of radio measurements of cosmic-ray air showers at MHz frequencies, a detector timing synchronization within 1 ns is needed. Large distributed radio detector arrays such as the Auger Engineering Radio Array (AERA) rely on timing via the Global Positioning System (GPS) for the synchronization of individual detector station clocks. Unfortunately, GPS timing is expected to have an accuracy no better than about 5 ns. In practice, in particular in AERA, the GPS clocks exhibit drifts on the order of tens of ns. We developed a technique to correct for the GPS drifts, and an independent method used for cross-checks that indeed we reach nanosecond-scale timing accuracy by this correction. First, we operate a “beacon transmitter” which emits defined sine waves detected by AERA antennas recorded within the physics data. The relative phasing of these sine waves can be used to correct for GPS clock drifts. In addition to this, we observe radio pulses emitted by commercial airplanes, the position of which we determine in real time from Automatic Dependent Surveillance Broadcasts intercepted with a software-defined radio. From the known source location and the measured arrival times of the pulses we determine relative timing offsets between radio detector stations. We demonstrate with a combined analysis that the two methods give a consistent timing calibration with an accuracy of 2 ns or better. Consequently, the beacon method alone can be used in the future to continuously determine and correct for GPS clock drifts in each individual event measured by AERA.

  11. Software-Based Real-Time Acquisition and Processing of PET Detector Raw Data.

    PubMed

    Goldschmidt, Benjamin; Schug, David; Lerche, Christoph W; Salomon, André; Gebhardt, Pierre; Weissler, Bjoern; Wehner, Jakob; Dueppenbecker, Peter M; Kiessling, Fabian; Schulz, Volkmar

    2016-02-01

    In modern positron emission tomography (PET) readout architectures, the position and energy estimation of scintillation events (singles) and the detection of coincident events (coincidences) are typically carried out on highly integrated, programmable printed circuit boards. The implementation of advanced singles and coincidence processing (SCP) algorithms for these architectures is often limited by the strict constraints of hardware-based data processing. In this paper, we present a software-based data acquisition and processing architecture (DAPA) that offers a high degree of flexibility for advanced SCP algorithms through relaxed real-time constraints and an easily extendible data processing framework. The DAPA is designed to acquire detector raw data from independent (but synchronized) detector modules and process the data for singles and coincidences in real-time using a center-of-gravity (COG)-based, a least-squares (LS)-based, or a maximum-likelihood (ML)-based crystal position and energy estimation approach (CPEEA). To test the DAPA, we adapted it to a preclinical PET detector that outputs detector raw data from 60 independent digital silicon photomultiplier (dSiPM)-based detector stacks and evaluated it with a [(18)F]-fluorodeoxyglucose-filled hot-rod phantom. The DAPA is highly reliable with less than 0.1% of all detector raw data lost or corrupted. For high validation thresholds (37.1 ± 12.8 photons per pixel) of the dSiPM detector tiles, the DAPA is real time capable up to 55 MBq for the COG-based CPEEA, up to 31 MBq for the LS-based CPEEA, and up to 28 MBq for the ML-based CPEEA. Compared to the COG-based CPEEA, the rods in the image reconstruction of the hot-rod phantom are only slightly better separable and less blurred for the LS- and ML-based CPEEA. While the coincidence time resolution (∼ 500 ps) and energy resolution (∼12.3%) are comparable for all three CPEEA, the system sensitivity is up to 2.5 × higher for the LS- and ML-based CPEEA.

  12. Diamond detectors for time-of-flight measurements in laser-generated plasmas

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Margarone, D.; Milani, E.; Verona-Rinati, G.; Prestopino, G.; Tuvè, C.; Potenza, R.; Láska, L.; Krása, J.; Ullschmied, J.

    CVD mono-crystalline diamond thin films deposited on a doped diamond and aluminum backing were employed as detectors of the radiation emitted from the laser-generated plasma. Laser-matter interactions were obtained by the use of an Nd:Yag repetitive laser at INFN-LNS in Catania operating at 1010 W/cm2 pulse intensity, and a high-power iodine PALS laser in Prague operating at 1015 W/cm2 pulse intensity. Plasmas were obtained by ablating Al, Ta, Au, and CF2 bulk targets. Plasma characterization was carried out using diamond detectors and ion collectors placed at different distances and angles in relation to the position of the ablated target. Photons, electrons, and ions hitting the sensible volume of the detector generate electronhole pairs (loosing 13 eV for a pair), resulting in an arising of the voltage signal at the device electrodes, which is proportional to the deposited energy. Diamond detectors can measure UV, X-rays, electrons, and ions. The time-of-flight (TOF) technique was exploited to separate photon, electron, and particle contributions. Because of the high gap of the diamond band structure (5.48 eV), the detectors are blind to visible and IR light from the plasma, which results in very low background current. The TOF diamond spectra were compared with traditional ion collector spectra using the experimental data obtained from the experiments conducted at the Catania and Prague laboratories. The results indicate that the ion energy resolution of the employed diamond detectors is high and that the fast electrons can be detected from a deconvolution procedure applied to the fast photo-peak. Information about the mean energy of soft X-rays could be obtained by analyzing the fast contribute of the spectra acquired by using different absorber films.

  13. The Belle II imaging Time-of-Propagation (iTOP) detector

    DOE PAGES

    Fast, J.

    2017-02-16

    High precision flavor physics measurements are an essential complement to the direct searches for new physics at the LHC ATLAS and CMS experiments. We will perform these measurements using the upgraded Belle II detector that will take data at the SuperKEKB accelerator. With 40x the luminosity of KEKB, the detector systems must operate efficiently at much higher rates than the original Belle detector. A central element of the upgrade is the barrel particle identification system. Belle II has built and installed an imaging-Time-of-Propagation (iTOP) detector. The iTOP uses quartz optics as Cherenkov radiators. The photons are transported down the quartzmore » bars via total internal reflection with a spherical mirror at the forward end to reflect photons to the backward end where they are imaged onto an array of segmented Micro-Channel Plate Photo-Multiplier Tubes (MCP-PMTs). The system is read out using giga-samples per second waveform sampling Application-Specific Integrated Circuits (ASICs). Furthermore, we used the combined timing and spatial distribution of the photons for each event to determine particle species. This paper provides an overview of the iTOP system.« less

  14. Depth sensing technique using time-to-peak of anode signal in CZT detectors

    NASA Astrophysics Data System (ADS)

    Fu, Jianqiang; Li, Yulan; Zhang, Lan; Li, Yuanjing; Niu, Libo; Wang, Yiming; Liu, Yilin; Li, Jun; Du, Yingshuai; Zhang, Wei; Liu, Yanqing

    2015-10-01

    This paper presents a depth sensing technique implemented on the CZT detectors, which uses the amplitude and the time-to-peak of the anode signal to reconstruct the depth of interaction and the initial deposited energy. The principle and procedure of the reconstruction are described in detail. The feasibility of this technique implemented on a Pixel CZT detector was investigated through simulations and a prototype was fabricated for an experimental test. The experimental results demonstrated the effectiveness of this technique. Depth indexes reconstructed by time-to-peak were in agreement with depth sensing by the C/A ratio, and the performance of the reconstructed spectrum improved obviously. Extensive investigation showed that it is feasible to extend this technique to Strengthened Electric Field Line Anode (SEFLA) detectors. Although the depth sensing had some limitation in practical application due to the non-uniform electric field, energy resolution was significantly improved from 3.2% (FWHM@662 keV) to 1.7%. Efforts will be made to apply this technique on the portable spectrometric systems based on SEFLA detectors.

  15. Time-zero fission-fragment detector based on low-pressure multiwire proportional chambers

    SciTech Connect

    Assamagan, Ketevi; Baker, O.; Bayatian, G.; Carlini, Roger; Danagoulian, Areg; Eden, Thomas; Egiyan, Kim; Ent, Rolf; Fenker, Howard; Gan, Liping; Gasparian, Ashot; Grigoryan, Hovhannes; Greenwood, Z; Gueye, Paul; Hashimoto, Osamu; Johnston, Kathleen; Keppel, Cynthia; Knyazian, S.; Majewski, Stanislaw; Magaryan, A; Margarian, Yu.; Marikyan, Gagik; Martoff, Charles; Mkrtchyan, Hamlet; PARLAKYAN, L.; Parlakyan, L.; Sato, Ikuro; Sawafta, Reyad; Simicevic, Neven; Tadevosyan, Vardan; Takahashi, Toshiyuki; Tang, Liguang; VARTANYAN, G.; Vulcan, William; Wells, Steven; Wood, Stephen

    1999-05-01

    A time-zero fission fragment (FF) detector, based on the technique of low-pressure multiwire proportional chambers (LPMWPC), has been designed and constructed for the heavy hypernuclear lifetime experiment (E95-002) at Thomas Jefferson National Accelerator Facility. Its characteristics and the method of time-zero reconstruction were investigated using fission fragments from a 252Cf spontaneous fission source. The influence of the ionization energy loss was also studied. It is shown that Heptane, Hexane, and Isobutane gases at a pressure of 1z2Torr are all suitable for such a FF detector. As desired by experiment, a timing resolution of about 200ps (FWHM) for a chamber size of 21z21cm2 was achieved.

  16. Neutron monitors and muon detectors for solar modulation studies: 2. ϕ time series

    NASA Astrophysics Data System (ADS)

    Ghelfi, A.; Maurin, D.; Cheminet, A.; Derome, L.; Hubert, G.; Melot, F.

    2017-08-01

    The level of solar modulation at different times (related to the solar activity) is a central question of solar and galactic cosmic-ray physics. In the first paper of this series, we have established a correspondence between the uncertainties on ground-based detectors count rates and the parameter ϕ (modulation level in the force-field approximation) reconstructed from these count rates. In this second paper, we detail a procedure to obtain a reference ϕ time series from neutron monitor data. We show that we can have an unbiased and accurate ϕ reconstruction (Δϕ / ϕ ≃ 10 %). We also discuss the potential of Bonner spheres spectrometers and muon detectors to provide ϕ time series. Two by-products of this calculation are updated ϕ values for the cosmic-ray database and a web interface to retrieve and plot ϕ from the 50's to today (http://lpsc.in2p3.fr/crdb).

  17. Day of the Dead

    ERIC Educational Resources Information Center

    Dann, Tammy; Murphy, Amy

    2012-01-01

    Foreign Language in Elementary School (FLES) teachers in the West Des Moines schools incorporate the Day of the Dead into the fourth grade curriculum each year. The teachers discuss the Day of the Dead celebration at the Art Center, and many ask for volunteers from fourth grade to participate in the event. Student presentations include a wide…

  18. Investigating Aquatic Dead Zones

    ERIC Educational Resources Information Center

    Testa, Jeremy; Gurbisz, Cassie; Murray, Laura; Gray, William; Bosch, Jennifer; Burrell, Chris; Kemp, Michael

    2010-01-01

    This article features two engaging high school activities that include current scientific information, data, and authentic case studies. The activities address the physical, biological, and chemical processes that are associated with oxygen-depleted areas, or "dead zones," in aquatic systems. Students can explore these dead zones through both…

  19. Day of the Dead

    ERIC Educational Resources Information Center

    Dann, Tammy; Murphy, Amy

    2012-01-01

    Foreign Language in Elementary School (FLES) teachers in the West Des Moines schools incorporate the Day of the Dead into the fourth grade curriculum each year. The teachers discuss the Day of the Dead celebration at the Art Center, and many ask for volunteers from fourth grade to participate in the event. Student presentations include a wide…

  20. Investigating Aquatic Dead Zones

    ERIC Educational Resources Information Center

    Testa, Jeremy; Gurbisz, Cassie; Murray, Laura; Gray, William; Bosch, Jennifer; Burrell, Chris; Kemp, Michael

    2010-01-01

    This article features two engaging high school activities that include current scientific information, data, and authentic case studies. The activities address the physical, biological, and chemical processes that are associated with oxygen-depleted areas, or "dead zones," in aquatic systems. Students can explore these dead zones through both…

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

    SciTech Connect

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

    2015-05-27

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

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

    DOE PAGES

    Waugh, C. J.; Rosenberg, M. J.; Zylstra, A. B.; ...

    2015-05-27

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

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

    SciTech Connect

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

    2015-05-15

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

  4. Performance comparison of optimal fractional order hybrid fuzzy PID controllers for handling oscillatory fractional order processes with dead time.

    PubMed

    Das, Saptarshi; Pan, Indranil; Das, Shantanu

    2013-07-01

    Fuzzy logic based PID controllers have been studied in this paper, considering several combinations of hybrid controllers by grouping the proportional, integral and derivative actions with fuzzy inferencing in different forms. Fractional order (FO) rate of error signal and FO integral of control signal have been used in the design of a family of decomposed hybrid FO fuzzy PID controllers. The input and output scaling factors (SF) along with the integro-differential operators are tuned with real coded genetic algorithm (GA) to produce optimum closed loop performance by simultaneous consideration of the control loop error index and the control signal. Three different classes of fractional order oscillatory processes with various levels of relative dominance between time constant and time delay have been used to test the comparative merits of the proposed family of hybrid fractional order fuzzy PID controllers. Performance comparison of the different FO fuzzy PID controller structures has been done in terms of optimal set-point tracking, load disturbance rejection and minimal variation of manipulated variable or smaller actuator requirement etc. In addition, multi-objective Non-dominated Sorting Genetic Algorithm (NSGA-II) has been used to study the Pareto optimal trade-offs between the set point tracking and control signal, and the set point tracking and load disturbance performance for each of the controller structure to handle the three different types of processes. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  5. Supernova neutrino physics with xenon dark matter detectors: A timely perspective

    NASA Astrophysics Data System (ADS)

    Lang, Rafael F.; McCabe, Christopher; Reichard, Shayne; Selvi, Marco; Tamborra, Irene

    2016-11-01

    Dark matter detectors that utilize liquid xenon have now achieved tonne-scale targets, giving them sensitivity to all flavors of supernova neutrinos via coherent elastic neutrino-nucleus scattering. Considering for the first time a realistic detector model, we simulate the expected supernova neutrino signal for different progenitor masses and nuclear equations of state in existing and upcoming dual-phase liquid xenon experiments. We show that the proportional scintillation signal (S2) of a dual-phase detector allows for a clear observation of the neutrino signal and guarantees a particularly low energy threshold, while the backgrounds are rendered negligible during the supernova burst. XENON1T (XENONnT and LZ; DARWIN) experiments will be sensitive to a supernova burst up to 25 (35; 65) kpc from Earth at a significance of more than 5 σ , observing approximately 35 (123; 704) events from a 27 M⊙ supernova progenitor at 10 kpc. Moreover, it will be possible to measure the average neutrino energy of all flavors, to constrain the total explosion energy, and to reconstruct the supernova neutrino light curve. Our results suggest that a large xenon detector such as DARWIN will be competitive with dedicated neutrino telescopes, while providing complementary information that is not otherwise accessible.

  6. The UCSD high energy X-ray timing experiment cosmic ray particle anticoincidence detector

    NASA Technical Reports Server (NTRS)

    Hink, P. L.; Rothschild, R. E.; Pelling, M. R.; Macdonald, D. R.; Gruber, D. E.

    1991-01-01

    The HEXTE, part of the X-Ray Timing Explorer (XTE), is designed to make high sensitivity temporal and spectral measurements of X-rays with energies between 15 and 250 keV using NaI/CsI phoswich scintillation counters. To achieve the required sensitivity it is necessary to provide anticoincidence of charged cosmic ray particles incident upon the instrument, some of which interact to produce background X-rays. The proposed cosmic ray particle anticoincidence shield detector for HEXTE uses a novel design based on plastic scintillators and wavelength-shifter bars. It consists of five segments, each with a 7 mm thick plastic scintillator, roughly 50 cm x 50 cm in size, coupled to two wavelength-shifter bars viewed by 1/2 inch photomultiplier tubes. These segments are configured into a five-sided, box-like structure around the main detector system. Results of laboratory testing of a model segment, and calculations of the expected performance of the flight segments and particle anticoincidence detector system are presented to demonstrate that the above anticoincidence detector system satisfies its scientific requirements.

  7. Detection efficiency, spatial and timing resolution of thermal and cold neutron counting MCP detectors

    NASA Astrophysics Data System (ADS)

    Tremsin, A. S.; McPhate, J. B.; Vallerga, J. V.; Siegmund, O. H. W.; Hull, J. S.; Feller, W. B.; Lehmann, E.

    2009-06-01

    Neutron counting detectors with boron or gadolinium doped microchannel plates (MCPs) have very high detection efficiency, spatial and temporal resolution, and have a very low readout noise. In this paper we present the results of both theoretical predictions and experimental evaluations of detection efficiency and spatial resolution measured at cold and thermal neutron beamlines. The quantum detection efficiency of a detector (not fully optimized) was measured to be 43% and 16% for the cold and thermal beamlines, respectively. The experiments also demonstrate that the spatial resolution can be better than 15 μm—highest achievable with the particular MCP pore dimension used in the experiment, although more electronics development is required in order to increase the counting rate capabilities of those <15 μm resolution devices. The timing accuracy of neutron detection is on the scale of few μs and is limited by the neutron absorption depth in the detector. The good agreement between the predicted and measured performance allows the optimization of the detector parameters in order to achieve the highest spatial resolution and detection efficiency in future devices.

  8. Monte Carlo study of the time resolution of scintillating fibre detectors

    NASA Astrophysics Data System (ADS)

    Ziembicki, M.; Marzec, J.; Dziewiecki, M.

    2007-08-01

    This paper presents the results of a Monte Carlo study of the time resolution of a scintillating fibre detector and analyses its dependence on the various aspects of detector construction. The estimations of the theoretical time resolutions for detectors with different numbers of fibre layers and different types of acrylic-based fibre coatings are presented. The method is suggested to decrease the rate counting effects encountered in high rate applications. It has been observed that for dual cladding fibres with a fluorinated polymer used for the outer cladding, the most significant factor contributing to the time resolution is the number of fibre layers, with the fibre coating being the marginal one. Another observation shows that the introduction of a gap between the fibre and the photomultiplier glass window allows the reduction of the number of photoelectrons by 25% with only a slight decrease in the time resolution, which may be helpful in decreasing the pulse pile-up effects and the photomultiplier gain, commonly observed under high rate conditions.

  9. Toward a Real-Time In Vivo Dosimetry System Using Plastic Scintillation Detectors

    SciTech Connect

    Archambault, Louis; Briere, Tina M.; Poenisch, Falk; Beaulieu, Luc; Kuban, Deborah A.; Lee, Andrew; Beddar, Sam

    2010-09-01

    Purpose: In the present study, we have presented and validated a plastic scintillation detector (PSD) system designed for real-time multiprobe in vivo measurements. Methods and Materials: The PSDs were built with a dose-sensitive volume of 0.4 mm{sup 3}. The PSDs were assembled into modular detector patches, each containing five closely packed PSDs. Continuous dose readings were performed every 150 ms, with a gap between consecutive readings of <0.3 ms. We first studied the effect of electron multiplication. We then assessed system performance in acrylic and anthropomorphic pelvic phantoms. Results: The PSDs were compatible with clinical rectal balloons and were easily inserted into the anthropomorphic phantom. With an electron multiplication average gain factor of 40, a twofold increase in the signal/noise ratio was observed, making near real-time dosimetry feasible. Under calibration conditions, the PSDs agreed with the ion chamber measurements to 0.08%. Precision, evaluated as a function of the total dose delivered, ranged from 2.3% at 2 cGy to 0.4% at 200 cGy. Conclusion: Real-time PSD measurements are highly accurate and precise. These PSDs can be mounted onto rectal balloons, transforming these clinical devices into in vivo dose detectors without modifying current clinical practice. Real-time monitoring of the dose delivered near the rectum during prostate radiotherapy should help radiation oncologists protect this sensitive normal structure.

  10. Toward a real-time in vivo dosimetry system using plastic scintillation detectors

    PubMed Central

    Archambault, Louis; Briere, Tina M.; Pönisch, Falk; Beaulieu, Luc; Kuban, Deborah A.; Lee, Andrew; Beddar, Sam

    2010-01-01

    Purpose In this work, we present and validate a plastic scintillation detector (PSD) system designed for real-time multi-probe in vivo measurements. Methods and Materials The PSDs were built with a dose-sensitive volume of 0.4 mm3. PSDs were assembled into modular detector patches, each containing 5 closely packed PSDs. Continuous dose readings were performed every 150 ms, with a gap between consecutive readings of less than 0.3 ms. We first studied the effect of electron multiplication. We then assessed system performance in acrylic and anthropomorphic pelvic phantoms. Results The PSDs are compatible with clinical rectal balloons and are easily inserted into the anthropomorphic phantom. With an electron multiplication average gain factor of 40, a twofold increase in the signal-to-noise ratio was observed, making near real-time dosimetry feasible. Under calibration conditions, the PSDs agreed with ion chamber measurements to 0.08%. Precision, evaluated as a function of the total dose delivered, ranged from 2.3% at 2 cGy to 0.4% at 200 cGy. Conclusion Real-time PSD measurements are highly accurate and precise. These PSDs can be mounted onto rectal balloons, transforming these clinical devices into in vivo dose detectors without modifying current clinical practice. Real-time monitoring of the dose delivered near the rectum during prostate radiation therapy should help radiation oncologists protect this sensitive normal structure. PMID:20231074

  11. Exploring challenges to TTO utilities: valuing states worse than dead.

    PubMed

    Robinson, Angela; Spencer, Anne

    2006-04-01

    The conventional time trade off (TTO) method relies on fundamentally different procedures to assess states better than and worse than dead. Arbitrary transformation mechanisms are then applied to worse than dead scores in order to achieve symmetry with those rated as better than dead. We use a 'life profile' approach along with a ranking procedure in order to show how states rated worse than dead may be assessed in exactly the same manner as better than dead scores. We then explore a common issue associated with states worse than dead that has received some attention recently: maximal endurable time. Our results showed that, although the severe health state was commonly rated as worse than dead, there were relatively few respondents that exhibited MET preferences. We discuss the implications of our findings for the use of the TTO method in deriving values for states that are worse than dead.

  12. Time-over-threshold for pulse shape discrimination in a time-of-flight phoswich PET detector

    NASA Astrophysics Data System (ADS)

    Chang, Chen-Ming; Cates, Joshua W.; Levin, Craig S.

    2017-01-01

    It is well known that a PET detector capable of measuring both photon time-of-flight (TOF) and depth-of-interaction (DOI) improves the image quality and accuracy. Phoswich designs have been realized in PET detectors to measure DOI for more than a decade. However, PET detectors based on phoswich designs put great demand on the readout circuits, which have to differentiate the pulse shape produced by different crystal layers. A simple pulse shape discrimination approach is required to realize the phoswich designs in a clinical PET scanner, which consists of thousands of scintillation crystal elements. In this work, we studied time-over-threshold (ToT) as a pulse shape parameter for DOI. The energy, timing and DOI performance were evaluated for a phoswich detector design comprising 3~\\text{mm}× 3~\\text{mm}× 10 mm LYSO:Ce crystal optically coupled to 3~\\text{mm}× 3~\\text{mm}× 10 mm calcium co-doped LSO:Ce,Ca(0.4%) crystal read out by a silicon photomultiplier (SiPM). A DOI accuracy of 97.2% has been achieved for photopeak events using the proposed time-over-threshold (ToT) processing. The energy resolution without correction for SiPM non-linearity was 9.7+/- 0.2 % and 11.3+/- 0.2 % FWHM at 511 keV for LYSO and LSO crystal layers, respectively. The coincidence time resolution for photopeak events ranges from 164.6 ps to 183.1 ps FWHM, depending on the layer combinations. The coincidence time resolution for inter-crystal scatter events ranges from 214.6 ps to 418.3 ps FWHM, depending on the energy windows applied. These results show great promises of using ToT for pulse shape discrimination in a TOF phoswich detector since a ToT measurement can be easily implemented in readout electronics.

  13. 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

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

    NASA Astrophysics Data System (ADS)

    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.

    2013-02-01

    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.

  15. Space-borne gravitational-wave detectors as time-delayed differential dynamometers

    NASA Astrophysics Data System (ADS)

    Congedo, Giuseppe; Dolesi, Rita; Hueller, Mauro; Vitale, Stefano; Weber, William J.

    2013-10-01

    The basic constituent of many space-borne gravitational missions, in particular, for interferometric gravitational-wave detectors, is the so-called “link” made out of a satellite sending an electromagnetic beam to a second satellite. We illustrate how, by measuring the time derivative of the frequency of the received beam, the link behaves as a differential, time-delayed dynamometer in which the effect of gravity is exactly equivalent to an effective differential force applied to the two satellites. We also show that this differential force gives an integrated measurement of curvature along the beam. Finally, we discuss how this approach can be implemented to benefit the data analysis of gravitational-wave detectors.

  16. Status and performance of the ALICE MRPC-based Time-Of-Flight detector

    NASA Astrophysics Data System (ADS)

    Alici, A.

    2012-10-01

    ALICE is the dedicated heavy-ion experiment at the CERN LHC. One of the main detectors devoted to charged hadron identification in the ALICE central barrel is a large Time-Of-Flight (TOF) array; it allows separation among pions, kaons and protons up to a few GeV/c, covering the full azimuthal angle and -0.9 < η < 0.9. The very good performance required for such a system has been achieved by means of the Multigap Resistive Plate Chamber (MRPC) whose intrinsic time resolution is better than 50 ps with an overall efficiency close to 100% and a large operational plateau; the full array consists of 1593 MRPCs covering a cylindrical surface of 141 m2. In this report, the status of the TOF detector and the performance achieved during the 2010 and 2011 data taking periods are reported together with selected physics results obtained with pp and Pb-Pb collisions.

  17. Optimization of a multi-ring detector for Ps time of flight measurements

    NASA Astrophysics Data System (ADS)

    Di Noto, L.; Benetti, M.; Mariazzi, S.; Dalla Betta, G.-F.; Brusa, R. S.

    2013-06-01

    We have designed a multi-ring detector (MRD) based on Bismuth Germanate (BGO) crystals, coupled to Silicon PhotoMultipliers (SiPM) for measuring the Ps time of flight (TOF). The set-up geometry was optimized by Monte Carlo simulations to take into account at different Ps velocities: (i) the background noise due to backscattered positrons, (ii) the crosstalk between adjacent detectors, (iii) the lifetime of Ps decay. Three parameters were defined to evaluate the different configurations and a figure of merit was obtained. This allows the choice of the best set up configuration for measuring Ps emitted with a particular energy range, optimizing the signal to noise ratio and keeping the acquisition time acceptable.

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

    PubMed

    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

    2013-02-01

    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.

  19. Algorithms for the determination of the time delays of the signal when using unequal detectors

    NASA Technical Reports Server (NTRS)

    Novak, B. L.

    1979-01-01

    In treating the recorded results from detectors at different locations in space, the analysis of the time delays of signals is crucial to locating the sources of detected radiation. Because the correlation method requires the manipulation of awkward matrices to evaluate its accuracy, a solution is outlined based on minimizing the sum of the squares of signal deviations, and the algorithms for evaluating the resulting error are presented.

  20. Visualisation of blood and lymphatic vessels with increasing exposure time of the detector

    SciTech Connect

    Kalchenko, V V; Kuznetsov, Yu L; Meglinski, I V

    2013-07-31

    We describe the laser speckle contrast method for simultaneous noninvasive imaging of blood and lymphatic vessels of living organisms, based on increasing detector exposure time. In contrast to standard methods of fluorescent angiography, this technique of vascular bed imaging and lymphatic and blood vessel demarcation does not employ toxic fluorescent markers. The method is particularly promising with respect to the physiology of the cardiovascular system under in vivo conditions. (laser applications in biology and medicine)

  1. Visualisation of blood and lymphatic vessels with increasing exposure time of the detector

    NASA Astrophysics Data System (ADS)

    Kalchenko, V. V.; Kuznetsov, Yu L.; Meglinski, I. V.

    2013-07-01

    We describe the laser speckle contrast method for simultaneous noninvasive imaging of blood and lymphatic vessels of living organisms, based on increasing detector exposure time. In contrast to standard methods of fluorescent angiography, this technique of vascular bed imaging and lymphatic and blood vessel demarcation does not employ toxic fluorescent markers. The method is particularly promising with respect to the physiology of the cardiovascular system under in vivo conditions.

  2. Development and tests of MCP based timing and multiplicity detector for MIPs

    NASA Astrophysics Data System (ADS)

    Feofilov, G.; Kondratev, V.; Stolyarov, O.; Tulina, T.; Valiev, F.; Vinogradov, L.

    2017-01-01

    We present summary of technological developments and tests of the MCP based large area detector aimed at precise timing and charged particles multiplicity measurements. Results obtained in course of these developments of isochronous (simultaneity) precise signal readout, passive summation of 1 ns signals, fast (1 GHz) front-end electronics, miniature vacuum systems, etc. could be potentially interesting for a number of future applications in different fields.

  3. Note: Space qualified photon counting detector for laser time transfer with picosecond precision and stability

    NASA Astrophysics Data System (ADS)

    Prochazka, Ivan; Kodet, Jan; Blazej, Josef

    2016-05-01

    The laser time transfer link is under construction for the European Space Agency in the frame of Atomic Clock Ensemble in Space. We have developed and tested the flying unit of the photon counting detector optimized for this space mission. The results are summarized in this Note. An extreme challenge was to build a detector package, which is rugged, small and which provides long term detection delay stability on picosecond level. The device passed successfully all the tests required for space missions on the low Earth orbits. The detector is extremely rugged and compact. Its long term detection delay stability is excellent, it is better than ±1 ps/day, in a sense of time deviation it is better than 0.5 ps for averaging times of 2000 s to several hours. The device is capable to operate in a temperature range of -55 °C up to +60 °C, the change of the detection delay with temperature is +0.5 ps/K. The device is ready for integration into the space structure now.

  4. An infrared motion detector system for lossless real-time monitoring of animal preference tests.

    PubMed

    Pogány, A; Heszberger, J; Szurovecz, Zita; Vincze, E; Székely, T

    2014-12-01

    Automated behavioural observations are routinely used in many fields of biology, including ethology, behavioural ecology and physiology. When preferences for certain resources are investigated, the focus is often on simple response variables, such as duration and frequency of visits to choice chambers. Here we present an automated motion detector system that use passive infrared sensors to eliminate many drawbacks of currently existing methods. Signals from the sensors are processed by a custom-built interface, and after unnecessary data is filtered by a computer software, the total time and frequency of the subject's visits to each of the choice chambers are calculated. We validate the detector system by monitoring (using the system) and in the same time video recording mating preferences of zebra finches in a four-way choice apparatus. Manual scoring of the video recordings showed very high consistency with data from the detector system both for time and for frequency of visits. Furthermore, the validation revealed that if we used micro-switches or light barriers, the most commonly applied automatic detection techniques, this would have resulted in approximately 22% less information compared to our lossless system. The system provides a low-cost alternative for monitoring animal movements, and we discuss its further applicability.

  5. Digitial readout for microwave kinetic inductance detectors and applications in high time resolution astronomy

    NASA Astrophysics Data System (ADS)

    Strader, Matthew James

    This dissertation spans two topics relating to optical to near-infrared astronomical cameras built around Microwave Kinetic Inductance Detectors (MKIDs). The first topic is the development of a digital readout system for 10- to 30-kilopixel arrays of MKIDs. MKIDs are superconducting detectors that can detect individual photons with a wide range of wavelengths with high time resolution (SI{2}{micro s}) and low energy resolution. The advantage of MKIDs over other low temperature detectors with similar capabilities is that it is relatively straightforward to multiplex MKIDs into large arrays. All the complexity of readout is in room temperature electronics. This work discusses the implementation and programming of these electronics. The second part of this work demonstrates the capabilities of the prototype optical and near-infrared MKID instrument with observations of pulsars. Detecting optical pulsations in these objects require high time resolution and low noise. The discovery of a correlation between the brightness of optical pulses from the Crab pulsar and the time of arrival of coincident giant radio pulses is presented. The search for optical pulses from a millisecond pulsar J0337+1715 is discussed along with a new upper limit on the brightness of its optical pulses.

  6. Note: Space qualified photon counting detector for laser time transfer with picosecond precision and stability.

    PubMed

    Prochazka, Ivan; Kodet, Jan; Blazej, Josef

    2016-05-01

    The laser time transfer link is under construction for the European Space Agency in the frame of Atomic Clock Ensemble in Space. We have developed and tested the flying unit of the photon counting detector optimized for this space mission. The results are summarized in this Note. An extreme challenge was to build a detector package, which is rugged, small and which provides long term detection delay stability on picosecond level. The device passed successfully all the tests required for space missions on the low Earth orbits. The detector is extremely rugged and compact. Its long term detection delay stability is excellent, it is better than ±1 ps/day, in a sense of time deviation it is better than 0.5 ps for averaging times of 2000 s to several hours. The device is capable to operate in a temperature range of -55 °C up to +60 °C, the change of the detection delay with temperature is +0.5 ps/K. The device is ready for integration into the space structure now.

  7. Note: Space qualified photon counting detector for laser time transfer with picosecond precision and stability

    SciTech Connect

    Prochazka, Ivan Blazej, Josef; Kodet, Jan

    2016-05-15

    The laser time transfer link is under construction for the European Space Agency in the frame of Atomic Clock Ensemble in Space. We have developed and tested the flying unit of the photon counting detector optimized for this space mission. The results are summarized in this Note. An extreme challenge was to build a detector package, which is rugged, small and which provides long term detection delay stability on picosecond level. The device passed successfully all the tests required for space missions on the low Earth orbits. The detector is extremely rugged and compact. Its long term detection delay stability is excellent, it is better than ±1 ps/day, in a sense of time deviation it is better than 0.5 ps for averaging times of 2000 s to several hours. The device is capable to operate in a temperature range of −55 °C up to +60 °C, the change of the detection delay with temperature is +0.5 ps/K. The device is ready for integration into the space structure now.

  8. The CDFII time-of-flight detector and impact on beauty flavor tagging

    SciTech Connect

    C. Grozis et al.

    2002-12-03

    Following the successful RunI from 1992 to 1996, the CDF detector has undergone a major upgrade [1] for the RunII which begun in March 2001. The approval for the addition of a Time-of-Flight detector was granted in January 1999. The installation of the TOF detector was completed in August 2001 and its data has been included in the CDFII readout since then. The primary physics motivation for TOF is to complement and enhance the particle identification capability provided by the central drift chamber (COT) since it distinguishes K{sup {+-}} and {pi}{sup {+-}} in the momentum region of their cross-over in dE=dX. With an expected time-of-flight resolution of 100 ps, the TOF system will be capable of identifying charged kaons from pions by their flight time difference with at least two standard deviation separation up to kaon momenta of 1.6 GeV/c. Such an addition results in an enhancement of the b flavor identification power, crucial to improve the statistical precision in CP violation and B{sub s} mixing measurements.

  9. A real-time QRS detector based on discrete wavelet transform and cubic spline interpolation.

    PubMed

    Zheng, Huabin; Wu, Jiankang

    2008-10-01

    QRS detection is an important step in electrocardiogram signal processing and analysis. Despite a lot of research effort, robustness and high detection accuracy still remain open problems. Here we present a real-time QRS detector, based on wavelet decomposition and spline interpolation, which is working in our portable health monitor system (PHMS). The discrete wavelet transform combined with the Cubic Spline Interpolation is used as the preprocessor. An improved dynamic weights adjusting strategy is adopted to enhance the detection robustness. Finally, peak detector and adaptive threshold detector are used to determine the R fiducial point. We tested the algorithm against the Massachusetts Institute of Technology-Beth Israel Hosptial (MIT-BIH) arrhythmia database, and achieved a sensitivity of 99.75% and positive prediction of 99.83%. Further experiments carried out in the PHMS showed the robustness and sound performance in processing real-time sampled signal despite heavy noise. Time accuracy was also taken into consideration in the test and the total root mean square error was 16.03 ms.

  10. Precision electronics for a system of custom MCPs in the TORCH Time of Flight detector

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

    The TORCH detector will provide charged particle pi/K/p identification up to 10 GeV/c, combining Time-of-Flight and Cherenkov techniques to achieve a timing resolution of 70 ps for single photons. Based on a scalable design, a Time-of-Flight electronics readout system has been developed to instrument a novel customized 512-channel Micro Channel Plate (MCP) device. A Gigabit Ethernet-based readout scheme that operates the TORCH demonstration unit consisting of ten such MCPs will be reported. The trigger and clock distribution will also be discussed.

  11. Effects of etching time on alpha tracks in Solid state Nuclear Track Detectors

    NASA Astrophysics Data System (ADS)

    Gillmore, Gavin; Wertheim, David; Crust, Simon

    2013-04-01

    Inhalation of radon gas is thought to be the cause of about 1100 lung cancer related deaths each year in the UK (1). Radon concentrations can be monitored using Solid State Nuclear Track Detectors (SSNTDs) as the natural decay of radon results in alpha particles which form tracks in the detectors and these tracks can be etched in order to enable microscopic analysis. We have previously shown that confocal microscopy can be used for 3D visualisation of etched SSNTDs (2, 3). The aim of the study was to examine the effect of etching time on the appearance of alpha tracks in SSNTDs. Six SSNTDs were placed in a chamber with a luminous dial watch for a fixed period. The detectors were etched for between 30 minutes and 4.5 hours using 6M NaOH at a temperature of 90oC. A 'LEXT' OLS4000 confocal laser scanning microscope (Olympus Corporation, Japan) was used to acquire 2D and 3D image datasets of CR-39 plastic SSNTDs. Confocal microscope 3D images were acquired using a x50 or x100 objective lens. Data were saved as images and also spreadsheet files with height measurements. Software was written using MATLAB (The MathWorks Inc., USA) to analyse the height data. Comparing the 30 minute and 4 hour etching time detectors, we observed that there were marked differences in track area; the lower the etching time the smaller the track area. The degree to which etching may prevent visualising adjacent tracks also requires further study as it is possible that etching could result in some tracks being subsumed in other tracks. On the other hand if there is too little etching, track sizes would be reduced and hence could be more difficult to image; thus there is a balance required to obtain suitable measurement accuracy. (1) Gray A, Read S, McGale P and Darby S. Lung cancer deaths from indoor radon and the cost effectiveness and potential of policies to reduce them. BMJ 2009; 338: a3110. (2) Wertheim D, Gillmore G, Brown L, and Petford N. A new method of imaging particle tracks in

  12. Vortex-crossing-induced timing jitter of superconducting nanowire single-photon detectors

    NASA Astrophysics Data System (ADS)

    Wu, Hao; Gu, Chao; Cheng, Yuhao; Hu, Xiaolong

    2017-08-01

    We investigate the timing properties of single-photon-triggered vortex (or anti-vortex) crossing in a current-biased superconducting nanowire and find that the time delays caused in the vortex-crossing process vary with the transverse positions on the nanowire where the photons are absorbed. The position-dependent time delays indicate that the vortex-crossing process induces timing jitter of a superconducting nanowire single-photon detector (SNSPD). The magnitude of this timing jitter further depends on various parameters, including the polarization of the incident photon, the bias current, and the width of the nanowire. This vortex-crossing-induced timing jitter might represent the lower bound of the timing jitter of the SNSPD and fundamentally limit its time-resolving capability.

  13. Are children living on dead-end streets more active? Near-home street patterns and school-going children's time spent outdoors in Dhaka, Bangladesh.

    PubMed

    Monsur, Muntazar; Mansur, Mohaimen; Islam, Mohammed Zakiul

    2016-12-06

    This study aimed to investigate relationships between near-home street patterns and children's time spent outdoors (TSO). Participants were 60 (n=60) school-age Dhaka children, 7-11years old (16 girls and 44 boys) selected by a two-phase cluster sampling method. Data were collected from September 2010 to June 2011 by visiting each of 60 children's homes. Children's mean TSOs (in minutes) were reported by parents' face-to-face interviews, and near-home street pattern data were collected by systematic direct observations. The researchers also collected data on seven socio-demographic variables and three neighborhood built-environment variables. A backward selection based multiple linear regression was used to examine association between children's TSO and near-home street patterns. Results (adjusted R(2)=0.66 for weekdays and 0.68 for weekend) suggested that children's TSO were significantly associated with near-home street type: dead-end instead of through streets (28min on weekdays, p<0.01 and 66min on weekend, p<0.01). The width of the street, level of its branching and availability of an open space or playground near the house are also positively associated with TSO. Near-home street features significantly contribute to TSO in school-going children of Dhaka. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Radiation-Resistant Photon-Counting Detector Package Providing Sub-ps Stability for Laser Time Transfer in Space

    NASA Technical Reports Server (NTRS)

    Prochzaka, Ivan; Kodat, Jan; Blazej, Josef; Sun, Xiaoli (Editor)

    2015-01-01

    We are reporting on a design, construction and performance of photon-counting detector packages based on silicon avalanche photodiodes. These photon-counting devices have been optimized for extremely high stability of their detection delay. The detectors have been designed for future applications in fundamental metrology and optical time transfer in space. The detectors have been qualified for operation in space missions. The exceptional radiation tolerance of the detection chip itself and of all critical components of a detector package has been verified in a series of experiments.

  15. Detector modules and spectrometers for the TIME-Pilot [CII] intensity mapping experiment

    NASA Astrophysics Data System (ADS)

    Hunacek, Jonathon; Bock, James; Bradford, C. Matt; Bumble, Bruce; Chang, Tzu-Ching; Cheng, Yun-Ting; Cooray, Asantha; Crites, Abigail; Hailey-Dunsheath, Steven; Gong, Yan; Li, Chao-Te; O'Brient, Roger; Shirokoff, Erik; Shiu, Corwin; Sun, Jason; Staniszewski, Zachary; Uzgil, Bade; Zemcov, Michael

    2016-07-01

    This proceeding presents the current TIME-Pilot instrument design and status with a focus on the close-packed modular detector arrays and spectrometers. Results of laboratory tests with prototype detectors and spectrometers are discussed. TIME-Pilot is a new mm-wavelength grating spectrometer array under development that will study the Epoch of Reionization (the period of time when the first stars and galaxies ionized the intergalactic medium) by mapping the fluctuations of the redshifted 157:7 μm emission line of singly ionized carbon ([CII]) from redshift z 5:2 to 8:5. As a tracer of star formation, the [CII] power spectrum can provide information on the sources driving reionization and complements 21 cm data (which traces neutral hydrogen in the intergalactic medium). Intensity mapping provides a measure of the mean [CII] intensity without the need to resolve and detect faint sources individually. We plan to target a 1 degree by 0.35 arcminute field on the sky and a spectral range of 199-305 GHz, producing a spatial-spectral slab which is 140 Mpc by 0.9 Mpc on-end and 1230 Mpc in the redshift direction. With careful removal of intermediate-redshift CO sources, we anticipate a detection of the halo-halo clustering term in the [CII] power spectrum consistent with current models for star formation history in 240 hours on the JCMT. TIME-Pilot will use two stacks of 16 parallel-plate waveguide spectrometers (one stack per polarization) with a resolving power R 100 and a spectral range of 183 to 326 GHz. The range is divided into 60 spectral channels, of which 16 at the band edges on each spectrometer serve as atmospheric monitors. The diffraction gratings are curved to produce a compact instrument, each focusing the diffracted light onto an output arc sampled by the 60 bolometers. The bolometers are built in buttable dies of 8 (low freqeuency) or 12 (high frequency) spectral channels by 8 spatial channels and are mated to the spectrometer stacks. Each detector

  16. Picosecond time-resolved laser pump/X-ray probe experiments using a gated single-photon-counting area detector.

    PubMed

    Ejdrup, T; Lemke, H T; Haldrup, K; Nielsen, T N; Arms, D A; Walko, D A; Miceli, A; Landahl, E C; Dufresne, E M; Nielsen, M M

    2009-05-01

    The recent developments in X-ray detectors have opened new possibilities in the area of time-resolved pump/probe X-ray experiments; this article presents the novel use of a PILATUS detector to achieve X-ray pulse duration limited time-resolution at the Advanced Photon Source (APS), USA. The capability of the gated PILATUS detector to selectively detect the signal from a given X-ray pulse in 24 bunch mode at the APS storage ring is demonstrated. A test experiment performed on polycrystalline organic thin films of alpha-perylene illustrates the possibility of reaching an X-ray pulse duration limited time-resolution of 60 ps using the gated PILATUS detector. This is the first demonstration of X-ray pulse duration limited data recorded using an area detector without the use of a mechanical chopper array at the beamline.

  17. USB 3.0 readout and time-walk correction method for Timepix3 detector

    NASA Astrophysics Data System (ADS)

    Turecek, D.; Jakubek, J.; Soukup, P.

    2016-12-01

    The hybrid particle counting pixel detectors of Medipix family are well known. In this contribution we present new USB 3.0 based interface AdvaDAQ for Timepix3 detector. The AdvaDAQ interface is designed with a maximal emphasis to the flexibility. It is successor of FitPIX interface developed in IEAP CTU in Prague. Its modular architecture supports all Medipix/Timepix chips and all their different readout modes: Medipix2, Timepix (serial and parallel), Medipix3 and Timepix3. The high bandwidth of USB 3.0 permits readout of 1700 full frames per second with Timepix or 8 channel data acquisition from Timepix3 at frequency of 320 MHz. The control and data acquisition is integrated in a multiplatform PiXet software (MS Windows, Mac OS, Linux). In the second part of the publication a new method for correction of the time-walk effect in Timepix3 is described. Moreover, a fully spectroscopic X-ray imaging with Timepix3 detector operated in the ToT mode (Time-over-Threshold) is presented. It is shown that the AdvaDAQ's readout speed is sufficient to perform spectroscopic measurement at full intensity of radiographic setups equipped with nano- or micro-focus X-ray tubes.

  18. On-chip time resolved detection of quantum dot emission using integrated superconducting single photon detectors

    PubMed Central

    Reithmaier, G.; Lichtmannecker, S.; Reichert, T.; Hasch, P.; Müller, K.; Bichler, M.; Gross, R.; Finley, J. J.

    2013-01-01

    We report the routing of quantum light emitted by self-assembled InGaAs quantum dots (QDs) into the optical modes of a GaAs ridge waveguide and its efficient detection on-chip via evanescent coupling to NbN superconducting nanowire single photon detectors (SSPDs). The waveguide coupled SSPDs primarily detect QD luminescence, with scattered photons from the excitation laser onto the proximal detector being negligible by comparison. The SSPD detection efficiency from the evanescently coupled waveguide modes is shown to be two orders of magnitude larger when compared with operation under normal incidence illumination, due to the much longer optical interaction length. Furthermore, in-situ time resolved measurements performed using the integrated detector show an average QD spontaneous emission lifetime of 0.95 ns, measured with a timing jitter of only 72 ps. The performance metrics of the SSPD integrated directly onto GaAs nano-photonic hardware confirms the strong potential for on-chip few-photon quantum optics using such semiconductor-superconductor hybrid systems. PMID:23712624

  19. On-chip time resolved detection of quantum dot emission using integrated superconducting single photon detectors.

    PubMed

    Reithmaier, G; Lichtmannecker, S; Reichert, T; Hasch, P; Müller, K; Bichler, M; Gross, R; Finley, J J

    2013-01-01

    We report the routing of quantum light emitted by self-assembled InGaAs quantum dots (QDs) into the optical modes of a GaAs ridge waveguide and its efficient detection on-chip via evanescent coupling to NbN superconducting nanowire single photon detectors (SSPDs). The waveguide coupled SSPDs primarily detect QD luminescence, with scattered photons from the excitation laser onto the proximal detector being negligible by comparison. The SSPD detection efficiency from the evanescently coupled waveguide modes is shown to be two orders of magnitude larger when compared with operation under normal incidence illumination, due to the much longer optical interaction length. Furthermore, in-situ time resolved measurements performed using the integrated detector show an average QD spontaneous emission lifetime of 0.95 ns, measured with a timing jitter of only 72 ps. The performance metrics of the SSPD integrated directly onto GaAs nano-photonic hardware confirms the strong potential for on-chip few-photon quantum optics using such semiconductor-superconductor hybrid systems.

  20. Neutron measurements with Time-Resolved Event-Counting Optical Radiation (TRECOR) detector

    NASA Astrophysics Data System (ADS)

    Brandis, M.; Vartsky, D.; Dangendorf, V.; Bromberger, B.; Bar, D.; Goldberg, M. B.; Tittelmeier, K.; Friedman, E.; Czasch, A.; Mardor, I.; Mor, I.; Weierganz, M.

    2012-04-01

    Results are presented from the latest experiment with a new neutron/gamma detector, a Time-Resolved, Event-Counting Optical Radiation (TRECOR) detector. It is composed of a scintillating fiber-screen converter, bending mirror, lens and Event-Counting Image Intensifier (ECII), capable of specifying the position and time-of-flight of each event. TRECOR is designated for a multipurpose integrated system that will detect Special Nuclear Materials (SNM) and explosives in cargo. Explosives are detected by Fast-Neutron Resonance Radiography, and SNM by Dual Discrete-Energy gamma-Radiography. Neutrons and gamma-rays are both produced in the 11B(d,n+γ)12C reaction. The two detection modes can be implemented simultaneously in TRECOR, using two adjacent radiation converters that share a common optical readout. In the present experiment the neutron detection mode was studied, using a plastic scintillator converter. The measurements were performed at the PTB cyclotron, using the 9Be(d,n) neutron spectrum obtained from a thick Be-target at Ed ~ 13 MeV\\@. The basic characteristics of this detector were investigated, including the Contrast Transfer Function (CTF), Point Spread Function (PSF) and elemental discrimination capability.

  1. Fluorescence particle detector for real-time quantification of viable organisms in air

    NASA Astrophysics Data System (ADS)

    Luoma, Greg; Cherrier, Pierre P.; Piccioni, Marc; Tanton, Carol; Herz, Steve; DeFreez, Richard K.; Potter, Michael; Girvin, Kenneth L.; Whitney, Ronald

    2002-02-01

    The ability to detect viable organisms in air in real time is important in a number of applications. Detecting high levels of airborne organisms in hospitals can prevent post-operative infections and the spread of diseases. Monitoring levels of airborne viable organisms in pharmaceutical facilities can ensure safe production of drugs or vaccines. Monitoring airborne bacterial levels in meat processing plants can help to prevent contamination of food products. Monitoring the level of airborne organisms in bio-containment facilities can ensure that proper procedures are being followed. Finally, detecting viable organisms in real time is a key to defending against biological agent attacks. This presentation describes the development and performance of a detector, based on fluorescence particle counting technology, where an ultraviolet laser is used to count particles by light scattering and elicit fluorescence from specific biomolecules found only in living organisms. The resulting detector can specifically detect airborne particles containing living organisms from among the large majority of other particles normally present in air. Efforts to develop the core sensor technology, focusing on integrating an UV laser with a specially designed particle-counting cell will be highlighted. The hardware/software used to capture the information from the sensor, provide an alarm in the presence of an unusual biological aerosol content will also be described. Finally, results from experiments to test the performance of the detector will be presented.

  2. The electro-mechanical integration of the NA62 GigaTracker time tagging pixel detector

    NASA Astrophysics Data System (ADS)

    Morel, M.; Kluge, A.; Aglieri Rinella, G.; Carassiti, V.; Ceccucci, A.; Daguin, J.; Fiorini, M.; Jarron, P.; Kaplon, J.; Mapelli, A.; Marchetto, F.; Noy, M.; Nuessle, G.; Perktold, L.; Petagna, P.; Riedler, P.

    2010-12-01

    The NA62 GigaTracker is a low mass time tagging hybrid pixel detector operating in a beam with a particle rate of 750 MHz. It consists of three stations with a sensor size of 60 × 27mm2 containing 18000 pixels, each 300 × 300μm2. The active area is connected to a matrix of 2 × 5 pixel ASICs, which time tag the arrival of the particles with a binning of 100 ps. The detector operates in vacuum at -20 to 0°C and the material budget per station must be below 0.5% X0. Due to the high radiation environment of 2 × 1014 1 MeV neutron equivalent cm-2/yr-1 it is planned to exchange the detector modules regularly. The low material budget, cooling requirements and the request for easy module access has driven the electro-mechanical integration of the GigaTracker, which is presented in this paper.

  3. Study of timing response and charge spectra of glass based Resistive Plate Chamber detectors for INO-ICAL experiment

    NASA Astrophysics Data System (ADS)

    Gaur, A.; Kumar, A.; Naimuddin, Md.

    2017-03-01

    Resistive Plate chambers (RPCs) are robust and affordable gaseous detectors that combine low cost with excellent timing, good spatial resolution and fast response to the incoming particles. The India Based Neutrino Observatory is an approved project aimed at building a magnetised Iron Calorimeter (ICAL) detector to study Neutrino physics and related issues. The ICAL experiment will utilize about 29000 RPC's as active detector elements, sandwiched between alternate plates of thick iron. The RPC detectors will be used to detect muons produced from the atmospheric neutrinos interaction with an iron target. The spatial information of the muons will be extracted from the two dimensional readout and the hit position in the respective layers. The up going and down going directionality will be obtained using the time stamp of hits in the active detectors. The charge induced by the particle and its behaviour with respect to the applied voltage play a significant role in designing the readout electronics for the detector. In this paper, we present the timing and charge measurement of single gap glass based RPC detectors. We will also report about studies on the dependence of the timing and charge response of these RPC detectors as a function of the gas composition.

  4. Brillouin optical time-domain reflectometry using up-conversion single-photon detector

    NASA Astrophysics Data System (ADS)

    Xia, Haiyun; Shangguan, Mingjia; Shentu, Guoliang; Wang, Chong; Qiu, Jiawei; Zheng, Mingyang; Xie, Xiuping; Dou, Xiankang; Zhang, Qiang; Pan, Jian-Wei

    2016-12-01

    A direct-detection Brillouin optical time-domain reflectometry (BOTDR) using an up-conversion photon-counting detector and an all-fiber structure Fabry-Perot scanning interferometer is demonstrated with shot-noise limited performance. Taking advantage of ultra-low noise equivalent power of the up-conversion photon-counting detector and high spectral resolution of the interferometer, the Brillouin spectra along a polarization maintaining fiber (PMF) are analyzed in the optical frequency domain directly. In contrast with heterodyne BOTDR, photon-counting BOTDR has better EM compatibility and faster speed in data processing. In experiments, using peak input power of 20 dBm, temperature profile along a 9 km PMF is retrieved according to the Brillouin shifts, with spatial/temporal resolution of 2 m/15 s. The precision is 0.7 °C at the leading end and 1.2 °C at the trailing end.

  5. A generalized description of the time dependent signals in extensive air shower detectors and its applications

    NASA Astrophysics Data System (ADS)

    Ave, M.; Roth, M.; Schulz, A.

    2017-02-01

    The expected signal in extensive air shower (EAS) detectors can be predicted with a 10% accuracy by a parameterization that depends on a set of global shower parameters: the energy, the depth of the electromagnetic shower maximum (Xmax) and the overall muon content. By classifying shower particles in four components (muonic, purely electromagnetic, electromagnetic stemming from muon interactions and decay and electromagnetic-from-low-energy hadrons), shower-to-shower fluctuations are minimized. We follow this scheme to propose a model to describe the arrival time distributions of secondary particles as measured with surface detectors in an EAS experiment. This model is then used to reconstruct Xmax in Monte Carlo data sets. As an example, we show that for the case of the Pierre Auger Observatory Xmax can be reconstructed with an accuracy of about 45 g/cm2 at 1019 eV.

  6. Advanced Photon Counting Imaging Detectors with 100ps Timing for Astronomical and Space Sensing Applications

    NASA Astrophysics Data System (ADS)

    Siegmund, O.; Vallerga, J.; Welsh, B.; Rabin, M.; Bloch, J.

    In recent years EAG has implemented a variety of high-resolution, large format, photon-counting MCP detectors in space instrumentation for satellite FUSE, GALEX, IMAGE, SOHO, HST-COS, rocket, and shuttle payloads. Our scheme of choice has been delay line readouts encoding photon event position centroids, by determination of the difference in arrival time of the event charge at the two ends of a distributed resistive-capacitive (RC) delay line. Our most commonly used delay line configuration is the cross delay line (XDL). In its simplest form the delay-line encoding electronics consists of a fast amplifier for each end of the delay line, followed by time-to-digital converters (TDC's). We have achieved resolutions of < 25 μm in tests over 65 mm x 65 mm (3k x3k resolution elements) with excellent linearity. Using high speed TDC's, we have been able to encode event positions for random photon rates of ~1 MHz, while time tagging events using the MCP output signal to better than 100 ps. The unique ability to record photon X,Y,T high fidelity information has advantages over "frame driven" recording devices for some important applications. For example we have built open face and sealed tube cross delay line detectors used for biological fluorescence lifetime imaging, observation of flare stars, orbital satellites and space debris with the GALEX satellite, and time resolved imaging of the Crab Pulsar with a telescope as small as 1m. Although microchannel plate delay line detectors meet many of the imaging and timing demands of various applications, they have limitations. The relatively high gain (107) reduces lifetime and local counting rate, and the fixed delay (10's of ns) makes multiple simultaneous event recording problematic. To overcome these limitations we have begun development of cross strip readout anodes for microchannel plate detectors. The cross strip (XS) anode is a coarse (~0.5 mm) multi-layer metal and ceramic pattern of crossed fingers on an alumina

  7. New class of neutron detectors

    SciTech Connect

    Czirr, J.B.

    1997-09-01

    An optimized neutron scattering instrument design must include all significant components, including the detector. For example, useful beam intensity is limited by detector dead time; detector pixel size determines the optimum beam diameter, sample size, and sample to detector distance; and detector efficiency vs. wavelength determines the available energy range. As an example of the next generation of detectors that could affect overall instrumentation design, we will describe a new scintillator material that is potentially superior to currently available scintillators. We have grown and tested several small, single crystal scintillators based upon the general class of cerium-activated lithium lanthanide borates. The outstanding characteristic of these materials is the high scintillation efficiency-as much as five times that of Li-glass scintillators. This increase in light output permits the practical use of the exothermic B (n, alpha) reaction for low energy neutron detection. This reaction provides a four-fold increase in capture cross section relative to the Li (n, alpha) reaction, and the intriguing possibility of demanding a charged-particle/gamma ray coincidence to reduce background detection rates. These new materials will be useful in the thermal and epithermal energy ran at reactors and pulsed neutron sources.

  8. Dead Sea Scrolls

    NASA Technical Reports Server (NTRS)

    1994-01-01

    A consortium of researchers from Jet Propulsion Laboratory and three other organizations used charged coupled devices (CCDs) and other imaging enhancement technology to decipher previously unreadable portions of the Dead Sea Scrolls. The technique has potentially important implications for archeology.

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

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

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

  10. Electro-Optic Time-to-Space Converter for Optical Detector Jitter Mitigation

    NASA Technical Reports Server (NTRS)

    Birnbaum, Kevin; Farr, William

    2013-01-01

    A common problem in optical detection is determining the arrival time of a weak optical pulse that may comprise only one to a few photons. Currently, this problem is solved by using a photodetector to convert the optical signal to an electronic signal. The timing of the electrical signal is used to infer the timing of the optical pulse, but error is introduced by random delay between the absorption of the optical pulse and the creation of the electrical one. To eliminate this error, a time-to-space converter separates a sequence of optical pulses and sends them to different photodetectors, depending on their arrival time. The random delay, called jitter, is at least 20 picoseconds for the best detectors capable of detecting the weakest optical pulses, a single photon, and can be as great as 500 picoseconds. This limits the resolution with which the timing of the optical pulse can be measured. The time-to-space converter overcomes this limitation. Generally, the time-to-space converter imparts a time-dependent momentum shift to the incoming optical pulses, followed by an optical system that separates photons of different momenta. As an example, an electro-optic phase modulator can be used to apply longitudinal momentum changes (frequency changes) that vary in time, followed by an optical spectrometer (such as a diffraction grating), which separates photons with different momenta into different paths and directs them to impinge upon an array of photodetectors. The pulse arrival time is then inferred by measuring which photodetector receives the pulse. The use of a time-to-space converter mitigates detector jitter and improves the resolution with which the timing of an optical pulse is determined. Also, the application of the converter enables the demodulation of a pulse position modulated signal (PPM) at higher bandwidths than using previous photodetector technology. This allows the creation of a receiver for a communication system with high bandwidth and high bits

  11. Real-time Automatic Detectors of P and S Waves Using Singular Values Decomposition

    NASA Astrophysics Data System (ADS)

    Kurzon, I.; Vernon, F.; Rosenberger, A.; Ben-Zion, Y.

    2013-12-01

    We implement a new method for the automatic detection of the primary P and S phases using Singular Value Decomposition (SVD) analysis. The method is based on a real-time iteration algorithm of Rosenberger (2010) for the SVD of three component seismograms. Rosenberger's algorithm identifies the incidence angle by applying SVD and separates the waveforms into their P and S components. We have been using the same algorithm with the modification that we filter the waveforms prior to the SVD, and then apply SNR (Signal-to-Noise Ratio) detectors for picking the P and S arrivals, on the new filtered+SVD-separated channels. A recent deployment in San Jacinto Fault Zone area provides a very dense seismic network that allows us to test the detection algorithm in diverse setting, such as: events with different source mechanisms, stations with different site characteristics, and ray paths that diverge from the SVD approximation used in the algorithm, (e.g., rays propagating within the fault and recorded on linear arrays, crossing the fault). We have found that a Butterworth band-pass filter of 2-30Hz, with four poles at each of the corner frequencies, shows the best performance in a large variety of events and stations within the SJFZ. Using the SVD detectors we obtain a similar number of P and S picks, which is a rare thing to see in ordinary SNR detectors. Also for the actual real-time operation of the ANZA and SJFZ real-time seismic networks, the above filter (2-30Hz) shows a very impressive performance, tested on many events and several aftershock sequences in the region from the MW 5.2 of June 2005, through the MW 5.4 of July 2010, to MW 4.7 of March 2013. Here we show the results of testing the detectors on the most complex and intense aftershock sequence, the MW 5.2 of June 2005, in which in the very first hour there were ~4 events a minute. This aftershock sequence was thoroughly reviewed by several analysts, identifying 294 events in the first hour, located in a

  12. A TPC (Time Projection Chamber) detector for the study of high multiplicity heavy ion collisions

    SciTech Connect

    Rai, G.; Arthur, A.; Bieser, F.; Harnden, C.W.; Jones, R.; Klienfelder, S.; Lee, K.; Matis, H.S.; Nakamura, M.; McParland, C.; Nesbitt, D.; Odyniec, G.; Olson, D.; Pugh, H.G.; Ritter, H.G.; Symons, T.J.M.; Wieman, H.; Wright, M.; Wright, R. ); Rudge, A. )

    1990-01-01

    The design of a Time Projection Chamber (TPC) detector with complete pad coverage is presented. The TPC will allow the measurements of high multiplicity ({approx} 200 tracks) relativistic nucleus-nucleus collisions initiated with the heaviest, most energetic projectiles available at the LBL BEVALAC accelerator facility. The front end electronics, composed of over 15,000 time sampling channels, will be located on the chamber. The highly integrated, custom designed, electronics and the VME based data acquisition system are described. 10 refs., 8 figs., 1 tab.

  13. Performance of HEXTE engineering model phoswich detectors. [High Energy X-ray Timing Experiment

    NASA Technical Reports Server (NTRS)

    Hink, Paul; Pelling, Michael; Rothschild, Richard

    1992-01-01

    The preliminary design for the 15-250 keV, 200/sq cm, phoswich detectors for the High Energy X-ray Timing Experiment for NASA's X-ray Timing Explorer mission has been completed, and the first engineering model has been fabricated. This unit has undergone extensive environmental and performance testing, including extended vibration, thermal range, resolution, uniformity, and pulse shape, and is within specifications for all tests. Broad beam energy resolution of better than 15 percent at 60 keV and clear separation of NaI and CsI pulse shape peaks are seen. The design and test results will be presented.

  14. Utilization of Neutron Bang-time CVD diamond detectors at the Z Accelerator

    NASA Astrophysics Data System (ADS)

    Chandler, Gordon; Hahn, Kelly; Ruiz, Carlos; Jones, Brent; Gomez, Matthew; Hess, Mark; Harding, Eric; Knapp, Patrick; Bur, James; Torres, Jose; Norris, Edward; Cooper, Gary; Styron, Jedediah; Moy, Ken; McKenna, Ian; Glebov, Vladimir; Fittinghoff, David; May, Mark; Snyder, Lucas

    2016-10-01

    We are utilizing Chemical Vapor Deposited (CVD) Diamond detectors at 2.3 meters on the Z accelerator to infer neutron bang-times from Magnetized Liner Inertial Fusion (MagLIF) sources yielding up to 3e12 DD neutrons and to bound the neutron time history of Deuterium Gas Puff loads producing 5e13 DD neutrons. The current implementation of the diagnostic and initial results will be shown as well as our future plans for the diagnostic. Sandia is sponsored by the U.S. DOE's NNSA under contract DE-AC04-94AL85000.

  15. Time and energy reconstruction at the electromagnetic calorimeter of the Belle-II detector

    NASA Astrophysics Data System (ADS)

    Aulchenko, V.; Bobrov, A.; Ferber, T.; Kuzmin, A.; Miyabayshi, K.; de Nardo, G.; Shebalin, V.; Sibidanov, A.; Usov, Yu.; Zhulanov, V.

    2017-08-01

    The Belle-II electromagnetic calorimeter inherited crystals and front-end electronics from the Belle detector, however the readout electronics was essentially modified. New electronics provides continuous digitization of the shaped signal followed by the signal wave form analysis with the further reconstruction of both, amplitude and time of the signal. The time information allows one to suppress background essentially. The algorithm, which is implemented in FPGA, is properly simulated. We implemented this algorithm to the simulation software and studied it with the MC background data. The procedure for the calibration of the response function has been developed and tested with the barrel counters using cosmic-ray data.

  16. Design, construction, characterization and use of a detector to measure time of flight of cosmic rays

    NASA Astrophysics Data System (ADS)

    Araujo, A. C.; Félix, J.

    2016-10-01

    In the study of cosmic rays, measurements of time of flight and momentum have been used to identify incident particles from its physical properties, like mass. In this poster we present the design, construction, characterization, and operation of a detector to measure time of flight of cosmic rays. The device is comprised of three plates of plastic scintillator arranged in vertical straight line, they are coupled to one photomultiplier tube. The analogical output has been connected to a data acquisition system to obtain the number of digital pulses per millisecond. We present preliminary results.

  17. A model-based, multichannel, real-time capable sawtooth crash detector

    NASA Astrophysics Data System (ADS)

    van den Brand, H.; de Baar, M. R.; van Berkel, M.; Blanken, T. C.; Felici, F.; Westerhof, E.; Willensdorfer, M.; The ASDEX Upgrade Team; The EUROfusion MST1 Team

    2016-07-01

    Control of the time between sawtooth crashes, necessary for ITER and DEMO, requires real-time detection of the moment of the sawtooth crash. In this paper, estimation of sawtooth crash times is demonstrated using the model-based interacting multiple model (IMM) estimator, based on simplified models for the sawtooth crash. In contrast to previous detectors, this detector uses the spatial extent of the sawtooth crash as detection characteristic. The IMM estimator is tuned and applied to multiple ECE channels at once. A model for the sawtooth crash is introduced, which is used in the IMM algorithm. The IMM algorithm is applied to seven datasets from the ASDEX Upgrade tokamak. Five crash models with different mixing radii are used. All sawtooth crashes that have been identified beforehand by visual inspection of the data, are detected by the algorithm. A few additional detections are made, which upon closer inspection are seen to be sawtooth crashes, which show a partial reconnection. A closer inspection of the detected normal crashes shows that about 42% are not well fitted by any of the full reconnection models and show some characteristics of a partial reconnection. In some case, the measurement time is during the sawtooth crashes, which also results in an incorrect estimate of the mixing radius. For data provided at a sampling rate of 1 kHz, the run time of the IMM estimator is below 1 ms, thereby fulfilling real-time requirements.

  18. Exploring the limiting timing resolution for large volume CZT detectors with waveform analysis.

    PubMed

    Meng, L J; He, Z

    2005-09-11

    This paper presents a study for exploring the limiting timing resolution that can be achieved with a large volume 3-D position sensitive CZT detector. The interaction timing information was obtained by fitting the measured cathode waveforms to pre-defined waveform models. We compared the results from using several different waveform models. Timing resolutions, of ~9.5 ns for 511 keV full-energy events and ~11.6 ns for all detected events with energy deposition above 250 keV, were achieved with a detailed modeling of the cathode waveform as a function of interaction location and energy deposition. This detailed modeling also allowed us to derive a theoretical lower bound for the error on estimated interaction timing. Both experimental results and theoretical predications matched well, which indicated that the best timing resolution achievable in the 1 cm(3) CZT detector tested is ~10 ns. It is also showed that the correlation between sampled amplitudes in cathode waveforms is an important limiting factor for the achievable timing resolution.

  19. Exploring the limiting timing resolution for large volume CZT detectors with waveform analysis

    PubMed Central

    Meng, L.J.; He, Z.

    2016-01-01

    This paper presents a study for exploring the limiting timing resolution that can be achieved with a large volume 3-D position sensitive CZT detector. The interaction timing information was obtained by fitting the measured cathode waveforms to pre-defined waveform models. We compared the results from using several different waveform models. Timing resolutions, of ~9.5 ns for 511 keV full-energy events and ~11.6 ns for all detected events with energy deposition above 250 keV, were achieved with a detailed modeling of the cathode waveform as a function of interaction location and energy deposition. This detailed modeling also allowed us to derive a theoretical lower bound for the error on estimated interaction timing. Both experimental results and theoretical predications matched well, which indicated that the best timing resolution achievable in the 1 cm3 CZT detector tested is ~10 ns. It is also showed that the correlation between sampled amplitudes in cathode waveforms is an important limiting factor for the achievable timing resolution. PMID:28260808

  20. Comparison of Signals from Gravitational Wave Detectors with Instantaneous Time-Frequency Maps

    NASA Technical Reports Server (NTRS)

    Stroeer, A.; Blackburn, L.; Camp, J.

    2011-01-01

    Gravitational wave astronomy relies on the use of multiple detectors, so that coincident detections may distinguish real signals from instrumental artifacts, and also so that relative timing of signals can provide the sky position of sources. We show that the comparison of instantaneous time-frequency and time-amplitude maps provided by the Hilbert-Huang Transform (HHT) can be used effectively for relative signal timing of common signals, to discriminate between the case of identical coincident signals and random noise coincidences and to provide a classification of signals based on their time-frequency trajectories. The comparison is done with a X(sup 2) goodness-offit method which includes contributions from both the instantaneous amplitude and frequency components of the HHT to match two signals in the time domain. This approach naturally allows the analysis of waveforms with strong frequency modulation.

  1. Inhomogeneity-induced timing jitter of superconducting nanowire single-photon detectors

    NASA Astrophysics Data System (ADS)

    Cheng, Yuhao; Gu, Chao; Hu, Xiaolong

    2017-08-01

    We show that the distributed electronic and geometric inhomogeneity of a superconducting nanowire induces timing jitter of the resulting single-photon detector and this timing jitter could be further exacerbated by localized constrictions. Due to the distributed inhomogeneity, photons absorbed at different locations of the nanowire generate hotspots that "sense" different local properties of the nanowire during the electro-thermal evolutions and thereby produce varying time delays. The localized constrictions limit the bias current, slow down the Joule-heating process, and consequently increase the average time delays and the inhomogeneity-induced timing jitter. We combine the Monte-Carlo method and the electro-thermal simulation to illustrate the inhomogeneity-induced timing jitter.

  2. Comparison of Signals from Gravitational Wave Detectors with Instantaneous Time-Frequency Maps

    NASA Technical Reports Server (NTRS)

    Stroeer, A.; Blackburn, L.; Camp, J.

    2011-01-01

    Gravitational wave astronomy relies on the use of multiple detectors, so that coincident detections may distinguish real signals from instrumental artifacts, and also so that relative timing of signals can provide the sky position of sources. We show that the comparison of instantaneous time-frequency and time-amplitude maps provided by the Hilbert-Huang Transform (HHT) can be used effectively for relative signal timing of common signals, to discriminate between the case of identical coincident signals and random noise coincidences and to provide a classification of signals based on their time-frequency trajectories. The comparison is done with a X(sup 2) goodness-offit method which includes contributions from both the instantaneous amplitude and frequency components of the HHT to match two signals in the time domain. This approach naturally allows the analysis of waveforms with strong frequency modulation.

  3. Positive operator-valued measure reconstruction of a beam-splitter tree-based photon-number-resolving detector.

    PubMed

    Piacentini, F; Levi, M P; Avella, A; López, M; Kück, S; Polyakov, S V; Degiovanni, I P; Brida, G; Genovese, M

    2015-04-01

    Here we present a reconstruction of the positive operator-value measurement of a photon-number-resolving detector comprised of three 50∶50 beam-splitters in a tree configuration, terminated with four single-photon avalanche detectors. The four detectors' outputs are processed by an electronic board that discriminates detected photon number states from 0 to 4 and implements a "smart counting" routine to compensate for dead time issues at high count rates.

  4. Improving the time response of a gamma/neutron liquid detector

    NASA Astrophysics Data System (ADS)

    Malone, Robert M.; Buckles, Robert A.; DeYoung, Anemarie; Garza, Irene; Frayer, Daniel K.; Kaufman, Morris I.; Morgan, George L.; Obst, Andrew W.; Rundberg, Robert S.; Tinsley, Jim; Waltman, Tom B.; Yuan, Vincent W.

    2016-09-01

    A pulsed neutron source is used to interrogate a target, producing secondary gammas and neutrons. In order to make good use of the relatively small number of gamma rays that emerge from the system after the neutron flash, our detector system must be both efficient in converting gamma rays to a detectable electronic signal and reasonably large in volume. Isotropic gamma rays are emitted from the target. These signals are converted to light within a large chamber of a liquid scintillator. To provide adequate time-of-flight separation between the gamma and neutron signals, the liquid scintillator is placed meters away from the target under interrogation. An acrylic PMMA (polymethyl methacrylate) light guide directs the emission light from the chamber into a 5-inch-diameter photomultiplier tube. However, this PMMA light guide produces a time delay for much of the light. Illumination design programs count rays traced from the source to a receiver. By including the index of refraction of the different materials that the rays pass through, the optical power at the receiver is calculated. An illumination design program can be used to optimize the optical material geometries to maximize the ray count and/or the receiver power. A macro was written to collect the optical path lengths of the rays and import them into a spreadsheet, where histograms of the time histories of the rays are plotted. This method allows optimization on the time response of different optical detector systems. One liquid scintillator chamber has been filled with a grid of reflective plates to improve its time response. Cylindrical detector geometries are more efficient.

  5. Development of a two-dimensional virtual-pixel X-ray imaging detector for time-resolved structure research.

    PubMed

    Orthen, Andre; Wagner, Hendrik; Martoiu, Sorin; Amenitsch, Heinz; Bernstorff, Sigrid; Besch, Hans Jürgen; Menk, Ralf Hendrik; Nurdan, Kivanç; Rappolt, Michael; Walenta, Albert Heinrich; Werthenbach, Ulrich

    2004-03-01

    An interpolating two-dimensional X-ray imaging detector based on a single-photon counter with gas amplification by GEM (gas electron multiplier) structures is presented. The detector system can be used for time-resolved structure research down to the micro s time domain. The prototype detector has been tested at the SAXS (small-angle X-ray scattering) beamline at ELETTRA synchrotron light source with a beam energy of 8 keV. The imaging performance is examined with apertures and standard diffraction targets. Finally, the application in a time-resolved lipid temperature-jump experiment is presented.

  6. Uncooled antenna-coupled terahertz detectors with 22 μs response time based on BiSb/Sb thermocouples

    NASA Astrophysics Data System (ADS)

    Huhn, Anna K.; Spickermann, Gunnar; Ihring, Andreas; Schinkel, Uwe; Meyer, Hans-Georg; Haring Bolívar, Peter

    2013-03-01

    We report on fast terahertz detectors based on antenna-coupled BiSb/Sb thermoelements operating at room temperature. A response time of the thermocouples as low as 22 μs and a noise equivalent power of 170 pW/√Hz at 1 kHz modulation frequency is measured in air at room temperature. The integration capability of these mass producible devices enables large-scale detector arrays for real-time terahertz imaging applications. Due to the fast response time, multiplexing of the detectors can be used to reduce the required readout circuits.

  7. A real-time spectrum acquisition system design based on quantum dots-quantum well detector

    NASA Astrophysics Data System (ADS)

    Zhang, S. H.; Guo, F. M.

    2016-01-01

    In this paper, we studied the structure characteristics of quantum dots-quantum well photodetector with response wavelength range from 400 nm to 1000 nm. It has the characteristics of high sensitivity, low dark current and the high conductance gain. According to the properties of the quantum dots-quantum well photodetectors, we designed a new type of capacitive transimpedence amplifier (CTIA) readout circuit structure with the advantages of adjustable gain, wide bandwidth and high driving ability. We have implemented the chip packaging between CTIA-CDS structure readout circuit and quantum dots detector and tested the readout response characteristics. According to the timing signals requirements of our readout circuit, we designed a real-time spectral data acquisition system based on FPGA and ARM. Parallel processing mode of programmable devices makes the system has high sensitivity and high transmission rate. In addition, we realized blind pixel compensation and smoothing filter algorithm processing to the real time spectrum data by using C++. Through the fluorescence spectrum measurement of carbon quantum dots and the signal acquisition system and computer software system to realize the collection of the spectrum signal processing and analysis, we verified the excellent characteristics of detector. It meets the design requirements of quantum dot spectrum acquisition system with the characteristics of short integration time, real-time and portability.

  8. Time and exposure dependent x-ray sensitivity in multilayer amorphous selenium detectors

    NASA Astrophysics Data System (ADS)

    Manouchehri, F.; Kabir, M. Z.; Tousignant, O.; Mani, H.; Devabhaktuni, V. K.

    2008-12-01

    A numerical model is developed to study the time and exposure dependent x-ray sensitivity of multilayer a-Se x-ray imaging detectors on repeated x-ray exposures by considering accumulated trapped charges and their effects (trap filling, recombination, electric field profile, electric field dependent electron-hole pair creation), the carrier transport in the blocking layers, x-ray induced metastable deep trap centre generations and the effects of charge injection. The time-dependent carrier detrapping and structural relaxation (recovery of metastable trap centres) are also considered. The continuity equations for both holes and electrons, trapping rate equations, and Poisson's equation across the photoconductor for a step x-ray exposure are simultaneously solved by the backward Euler finite difference method. The electric field distribution across the multilayer detector and the dark current density under repeated exposures are also estimated. The sensitivity in a rested sample is recovered mainly by the carrier detrapping and the recombination of the injected carriers with the existing trapped carriers. The sensitivity is expected to recover almost fully by resting the sample longer than the recovery time constant of the metastable trap centres (the structural relaxation time constant), which is in the range of several hours. The simulation result is fitted with the experimental data. The proposed theoretical model shows very good agreement with the experimental relative sensitivity versus time and accumulative x-ray exposure characteristics.

  9. The Large-Area Time-Of-Flight (TOF) Upgrade for the STAR Detector

    NASA Astrophysics Data System (ADS)

    Llope, W. J.

    2009-03-01

    The STAR experiment at RHIC concentrates on the tracking of charged hadrons via ionization in gas- and silicon-based detectors, and the detection of electrons and photons via calorimetry, in a wide and azimuthally complete acceptance that's unique at RHIC. STAR's ability to directly identify the tracked charged hadrons is however limited to low momenta. Approximately half of the charged particles in the event at higher momenta cannot be directly identified, which hampers the physics reach of STAR in a number of key areas. To address this blind spot, STAR is presently constructing a large-area (˜50 m2) Time-Of-Flight (TOF) system. This system is based on Multi-gap Resistive Plate Chambers (MRPCs). Prototype TOF systems based on this technology were operated in STAR during RHIC Runs 3 through 6, and the first 5 final-system trays were operated in the recent RHIC Run 8. A new "start detector" for this system has also been constructed and operated in STAR. The performance of these detectors in STAR, and an update on the status of the construction of the full system, is discussed.

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

    PubMed

    Karmarkar, Uma R; Buonomano, Dean V

    2002-07-01

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

  11. DETECTORS AND EXPERIMENTAL METHODS: Effect of the integrated time of the induced current signal on the position resolution of the RPC detector

    NASA Astrophysics Data System (ADS)

    Ye, Jin; Yue, Qian; Li, Yuan-Jing; Cheng, Jian-Ping; Li, Jin; Wang, Yi

    2009-08-01

    A prototype RPC with position resolution less than 1 mm has been produced and studied. Based on this RPC detector, the effect of the width of the integrated FADC time window on the position resolution of a RPC has been studied experimentally and theoretically. The results of theoretical calculation and experimental measurement have shown good agreement.

  12. First measurement of pp neutrinos in real time in the Borexino detector

    NASA Astrophysics Data System (ADS)

    Mosteiro, Pablo

    2014-09-01

    The Sun is fueled by a series of nuclear reactions that produce the energy that makes it shine. Neutrinos (nu) produced by these nuclear reactions exit the Sun and reach Earth within minutes, providing us with key information about what goes on at the core of our star. For over twenty years since the first detection of solar neutrinos in the late 1960's, an apparent deficit in their detection rate was known as the Solar Neutrino Problem. Today, the Mikheyev-Smirnov-Wolfenstein (MSW) effect is the accepted mechanism by which neutrinos oscillate inside the Sun, arriving at Earth as a mixture of nue, numu and nutau, the latter two of which were invisible to early detectors. Several experiments have now confirmed the observation of neutrino oscillations. These experiments, when their results are combined together, have demonstrated that neutrino oscillations are well described by the Large Mixing Angle (LMA) solution of the MSW effect. This thesis presents the first measurement of pp neutrinos in the Borexino detector, which is another validation of the LMA-MSW model of neutrino oscillations. In addition, it is one more step towards the completion of the spectroscopy of pp chain neutrinos in Borexino, leaving only the extremely faint hep neutrinos undetected. This advance validates the experiment itself and its previous results. This is, furthermore, the first direct real-time measurement of pp neutrinos. We find a pp neutrino detection rate of 143+/-16 (stat)+/-10 (syst) cpd/100 t in the Borexino experiment, which translates, according to the LMA-MSW model, to (6.42+/-0.85)x1010 cm -2 s-1. We also report on a measurement of neutrons in a dedicated system within the Borexino detector, which resulted in an improved understanding of neutron rates in liquid scintillator detectors at Gran Sasso depths. This result is crucial to the development of novel direct dark matter detection experiments.

  13. Particle identification with time-of-flight and pulse-shape discrimination in neutron-transmutation-doped silicon detectors

    NASA Astrophysics Data System (ADS)

    Mutterer, M.; Trzaska, W. H.; Kopatch, Yu. N.; Sillanpää, M.; von Kalben, J.; Khlebnikov, S. V.; Schrieder, G.; Tyurin, G. P.

    2009-09-01

    A method for the identification of energetic charged particles has been investigated based on the employment of pulse-shape discrimination (PSD) in a silicon detector in addition to conventional time-of-flight (ToF) techniques. The method makes use of the fact that, at fixed energy, the particle's velocity, or ToF, is a measure of the particle's mass A while the time structure of the current pulse in a silicon energy detector, used as the ToF stop, permits identification of nuclear charges Z. In the measurements presented here, ToF and PSD methods were applied simultaneously. We used micro-channel plate (MCP) detectors as fast time pick-offs and surface-barrier (SB) n-type Si detectors made from homogeneously neutron-transmutation-doped (n-TD) silicon. As the particles, products from the reactions of a 400 MeV 20Ne beam impinging on 12C, 27Al and 208Pb targets were employed. With using fast current-sensitive pre-amplifiers for the 250 and 800 μm SB detectors a major progress in particle identification with respect to both, mass A and charge Z was achieved. In addition, using a stack of two closely mounted n-TD SB detectors, a timing measurement between the two detectors permitted to study PSD in the rear detector with the time trigger derived from the foremost one. Finally, the internal PSD method was implemented which determines pulse rise-time in single detectors from analyzing differentiated preamplifier timing signals.

  14. Note: A large open ratio, time, and position sensitive detector for time of flight measurements in UHV.

    PubMed

    Lupone, S; Damoy, S; Husseen, A; Briand, N; Debiossac, M; Tall, S; Roncin, P

    2015-12-01

    We report on the construction of an UHV compatible 40 mm active diameter detector based on micro channel plates and assembled directly on the feed-throughs of a DN63CF flange. It is based on the charge division technique and uses a standard 2 inch Si wafer as a collector. The front end electronic is placed directly on the air side of the flange allowing excellent immunity to noise and a very good timing signal with reduced ringing. The important aberrations are corrected empirically providing an absolute positioning accuracy of 500 μm while a 150 μm resolution is measured in the center.

  15. Note: A large open ratio, time, and position sensitive detector for time of flight measurements in UHV

    SciTech Connect

    Lupone, S.; Damoy, S.; Husseen, A.; Briand, N.; Debiossac, M.; Tall, S.; Roncin, P.

    2015-12-15

    We report on the construction of an UHV compatible 40 mm active diameter detector based on micro channel plates and assembled directly on the feed-throughs of a DN63CF flange. It is based on the charge division technique and uses a standard 2 inch Si wafer as a collector. The front end electronic is placed directly on the air side of the flange allowing excellent immunity to noise and a very good timing signal with reduced ringing. The important aberrations are corrected empirically providing an absolute positioning accuracy of 500 μm while a 150 μm resolution is measured in the center.

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

    DOEpatents

    Goodman, Charles D.

    1979-01-01

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

  17. Monolithic single-photon detectors and time-to-digital converters for picoseconds time-of-flight ranging

    NASA Astrophysics Data System (ADS)

    Markovic, Bojan; Tisa, Simone; Tosi, Alberto; Zappa, Franco

    2011-03-01

    We present a novel "smart-pixel" able to measure and record in-pixel the time delay (photon timing) between a START (e.g. given by laser excitation, cell stimulus, or LIDAR flash) and a STOP (e.g. arrival of the first returning photon from the fluorescence decay signal or back reflection from an object). Such smart-pixel relies of a SPAD detector and a Timeto- Digital Converter monolithically designed and manufactured in the same chip. Many pixels can be laid out in a rows by columns architecture, to give birth to expandable 2D imaging arrays for picoseconds-level single-photon timing applications. Distance measurements, by means of direct TOF detection (used in LIDAR systems) provided by each pixel, can open the way to the fabrication of single-chip 3D ranging arrays for scene reconstruction and intelligent object recognition. We report on the design and characterization of prototype circuits, fabricated in a 0.35 μm standard CMOS technology containing complete conversion channels, "smart-pixel" and ancillary electronics with 20 μm active area diameter SPAD detector and related quenching circuitry. With a 100 MHz reference clock, the TDC provides timeresolution of 10 ps, dynamic range of 160 ns and very high conversion linearity.

  18. Beam test results of a 16 ps timing system based on ultra-fast silicon detectors

    NASA Astrophysics Data System (ADS)

    Cartiglia, N.; Staiano, A.; Sola, V.; Arcidiacono, R.; Cirio, R.; Cenna, F.; Ferrero, M.; Monaco, V.; Mulargia, R.; Obertino, M.; Ravera, F.; Sacchi, R.; Bellora, A.; Durando, S.; Mandurrino, M.; Minafra, N.; Fadeyev, V.; Freeman, P.; Galloway, Z.; Gkougkousis, E.; Grabas, H.; Gruey, B.; Labitan, C. A.; Losakul, R.; Luce, Z.; McKinney-Martinez, F.; Sadrozinski, H. F.-W.; Seiden, A.; Spencer, E.; Wilder, M.; Woods, N.; Zatserklyaniy, A.; Pellegrini, G.; Hidalgo, S.; Carulla, M.; Flores, D.; Merlos, A.; Quirion, D.; Cindro, V.; Kramberger, G.; Mandić, I.; Mikuž, M.; Zavrtanik, M.

    2017-04-01

    In this paper we report on the timing resolution obtained in a beam test with pions of 180 GeV/c momentum at CERN for the first production of 45 μm thick Ultra-Fast Silicon Detectors (UFSD). UFSD are based on the Low-Gain Avalanche Detector (LGAD) design, employing n-on-p silicon sensors with internal charge multiplication due to the presence of a thin, low-resistivity diffusion layer below the junction. The UFSD used in this test had a pad area of 1.7 mm2. The gain was measured to vary between 5 and 70 depending on the sensor bias voltage. The experimental setup included three UFSD and a fast trigger consisting of a quartz bar readout by a SiPM. The timing resolution was determined by doing Gaussian fits to the time-of-flight of the particles between one or more UFSD and the trigger counter. For a single UFSD the resolution was measured to be 34 ps for a bias voltage of 200 V, and 27 ps for a bias voltage of 230 V. For the combination of 3 UFSD the timing resolution was 20 ps for a bias voltage of 200 V, and 16 ps for a bias voltage of 230 V.

  19. Effects of etching time on alpha tracks in solid state nuclear track detectors.

    PubMed

    Gillmore, Gavin; Wertheim, David; Crust, Simon

    2017-01-01

    Solid State Nuclear Track Detectors (SSNTDs) are used extensively for monitoring alpha particle radiation, neutron flux and cosmic ray radiation. Radon gas inhalation is regarded as being a significant contributory factor to lung cancer deaths in the UK each year. Gas concentrations are often monitored using CR39 based SSNTDs as the natural decay of radon results in alpha particles which form tracks in these detectors. Such tracks are normally etched for about 4h to enable microscopic analysis. This study examined the effect of etching time on the appearance of alpha tracks in SSNTDs by collecting 2D and 3D image datasets using laser confocal microscope imaging techniques. Etching times of 2 to 4h were compared and marked differences were noted in resultant track area. The median equivalent diameters of tracks were 20.2, 30.2 and 38.9μm for etching at 2, 3 and 4h respectively. Our results indicate that modern microscope imaging can detect and image the smaller size tracks seen for example at 3h etching time. Shorter etching times may give rise to fewer coalescing tracks although there is a balance to consider as smaller track sizes may be more difficult to image. Thus etching for periods of less than 4h clearly merits further investigation as this approach has the potential to improve accuracy in assessing the number of tracks. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Effects of short immersion time and cooling rates of copperizing process to the evolution of microstructures and copper behavior in the dead mild steel

    NASA Astrophysics Data System (ADS)

    Jatimurti, Wikan; Sutarsis, Cunika, Aprida Ulya

    2017-01-01

    In a dead mild steel with maximum carbon content of 0.15%, carbon does not contribute much to its strength. By adding copper as an alloying element, a balance between strength and ductility could be obtained through grain refining, solid solution, or Cu precipitation. This research aimed to analyse the changes in microstructures and copper behaviour on AISI 1006, including the phases formed, composition, and Cu dispersion. The addition of cooper was done by immersing steel into molten copper or so we called, copperizing using the principles of diffusion. Specimens were cut with 6 × 3 × 0.3 cm measurement then preheated to 900°C and melting the copper at 1100°C. Subsequently, the immersion of the specimens into molten copper varied to 5 and 7 minutes, and also varying the cooling rate to annealing, normalizing, and quenching. A series of test being conduct were optical microscope test, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), optical emission spectroscopy (OES), and X-ray diffraction (XRD). The results showed that the longer the immersion time and slower cooling rate, the more Cu diffused causing smaller grain size with the highest Cu diffused recorded was 0.277% in the copperized AISI 1006 steel with 7 minutes of immersion and was annealed. The grain size reduced to 23041.5404 µm2. The annealed specimens show ferrite phase, the normalized ones show polygonal ferrite phase, while the quenched ones show granular bainite phase. The phase formed is single phase Cu. In addition, the normalized and quenched specimens show that Cu dissolved in Fe crystal forming solid solution.

  1. High rate particle tracking and ultra-fast timing with a thin hybrid silicon pixel detector

    NASA Astrophysics Data System (ADS)

    Fiorini, M.; Aglieri Rinella, G.; Carassiti, V.; Ceccucci, A.; Cortina Gil, E.; Cotta Ramusino, A.; Dellacasa, G.; Garbolino, S.; Jarron, P.; Kaplon, J.; Kluge, A.; Marchetto, F.; Mapelli, A.; Martin, E.; Mazza, G.; Morel, M.; Noy, M.; Nuessle, G.; Perktold, L.; Petagna, P.; Petrucci, F.; Poltorak, K.; Riedler, P.; Rivetti, A.; Statera, M.; Velghe, B.

    2013-08-01

    The Gigatracker (GTK) is a hybrid silicon pixel detector designed for the NA62 experiment at CERN. The beam spectrometer, made of three GTK stations, has to sustain high and non-uniform particle rate (∼ 1 GHz in total) and measure momentum and angles of each beam track with a combined time resolution of 150 ps. In order to reduce multiple scattering and hadronic interactions of beam particles, the material budget of a single GTK station has been fixed to 0.5% X0. The expected fluence for 100 days of running is 2 ×1014 1 MeV neq /cm2, comparable to the one foreseen in the inner trackers of LHC detectors during 10 years of operation. To comply with these requirements, an efficient and very low-mass (< 0.15 %X0) cooling system is being constructed, using a novel microchannel cooling silicon plate. Two complementary read-out architectures have been produced as small-scale prototypes: one is based on a Time-over-Threshold circuit followed by a TDC shared by a group of pixels, while the other makes use of a constant-fraction discriminator followed by an on-pixel TDC. The read-out ASICs are produced in 130 nm IBM CMOS technology and will be thinned down to 100 μm or less. An overview of the Gigatracker detector system will be presented. Experimental results from laboratory and beam tests of prototype bump-bonded assemblies will be described as well. These results show a time resolution of about 170 ps for single hits from minimum ionizing particles, using 200 μm thick silicon sensors.

  2. Design of Cherenkov bars for the optical part of the time-of-flight detector in Geant4.

    PubMed

    Nozka, L; Brandt, A; Rijssenbeek, M; Sykora, T; Hoffman, T; Griffiths, J; Steffens, J; Hamal, P; Chytka, L; Hrabovsky, M

    2014-11-17

    We present the results of studies devoted to the development and optimization of the optical part of a high precision time-of-flight (TOF) detector for the Large Hadron Collider (LHC). This work was motivated by a proposal to use such a detector in conjunction with a silicon detector to tag and measure protons from interactions of the type p + p → p + X + p, where the two outgoing protons are scattered in the very forward directions. The fast timing detector uses fused silica (quartz) bars that emit Cherenkov radiation as a relativistic particle passes through and the emitted Cherenkov photons are detected by, for instance, a micro-channel plate multi-anode Photomultiplier Tube (MCP-PMT). Several possible designs are implemented in Geant4 and studied for timing optimization as a function of the arrival time, and the number of Cherenkov photons reaching the photo-sensor.

  3. PMT overshoot study for the JUNO prototype detector

    NASA Astrophysics Data System (ADS)

    Luo, Feng-Jiao; Heng, Yue-Kun; Wang, Zhi-Min; Wang, Pei-Liang; Qin, Zhong-Hua; Xu, Mei-Hang; Liao, Dong-Hao; Zhang, Hai-Qiong; Huang, Yong-Bo; Lei, Xiang-Cui; Qian, Sen; Liu, Shu-Lin; Chen, Yuan-Bo; Wang, Yi-Fang

    2016-09-01

    The quality of PMT signals is crucial for large-size and high-precision neutrino experiments, but most of these experiments are affected by the overshoot of PMT signals from the positive HV-single cable scheme. Overshoot affects the trigger, dead time and charge measurement from a detector. For the JUNO prototype detector, we have performed a detailed study and calculation on PMT signal overshoot to control the ratio of overshoot to signal amplitude to ∼1%, with no effect on other PMT parameters. Supported by Strategic Priority Research Program A-JUNO, High Energy Physics Experiment and Detector R&D and National Natural Science Foundation of China

  4. Large Area Flat Panel Imaging Detectors for Astronomy and Night Time Sensing

    NASA Astrophysics Data System (ADS)

    Siegmund, O.; McPhate, J.; Frisch, H.; Elam, J.; Mane, A.; Wagner, R.; Varner, G.

    2013-09-01

    Sealed tube photo-sensing detectors for optical/IR detection have applications in astronomy, nighttime remote reconnaissance, and airborne/space situational awareness. The potential development of large area photon counting, imaging, timing detectors has significance for these applications and a number of other areas (High energy particle detection (RICH), biological single-molecule fluorescence lifetime imaging microscopy, neutron imaging, time of flight mass spectroscopy, diffraction imaging). We will present details of progress towards the development of a 20 cm sealed tube optical detector with nanoengineered microchannel plates for photon counting, imaging and sub-ns event time stamping. In the operational scheme of the photodetector incoming light passes through an entrance window and interacts with a semitransparent photocathode on the inside of the window. The photoelectrons emitted are accelerated across a proximity gap and are detected by an MCP pair. The pair of novel borosilicate substrate MCPs are functionalized by atomic layer deposition (ALD), and amplify the signal and the resulting electron cloud is detected by a conductive strip line anode for determination of the event positions and the time of arrival. The physical package is ~ 25 x 25 cm but only 1.5 cm thick. Development of such a device in a square 20 cm format presents challenges: hermetic sealing to a large entrance window, a 20 cm semitransparent photocathode with good efficiency and uniformity, 20 cm MCPs with reasonable cost and performance, robust construction to preserve high vacuum and withstand an atmosphere pressure differential. We will discuss the schemes developed to address these issues and present the results for the first test devices. The novel microchannel plates employing borosilicate micro-capillary arrays provide many performance characteristics typical of conventional MCPs, but have been made in sizes up to 20 cm, have low intrinsic background (0.08 events cm2 s-1) and

  5. Real-Time Detector of Human Fatigue: Detecting Lapses in Alertness

    DTIC Science & Technology

    2008-02-15

    DATES COVERED (From - To) 2/6/08 Final Report 3/15/2004 - 6/30/2007 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER (STTR PH II) REAL-TIME DETECTOR OF HUMAN...TELEPHONE NUMBER (include area 29 code) (530) 752-6999 Contractor: Bio-Behavior Analysis Systems, LLCBio-B ehavior Contract No.: FA9550-06-C-0008 Project...12 1 1 Contractor: Bio-Behavior Analysis Systems, LLCBio-B ehavior Contract No.: FA9550-06-C-0008 Project Title: (STTR

  6. Real-time operating system for a multi-laser/multi-detector system

    NASA Technical Reports Server (NTRS)

    Coles, G.

    1980-01-01

    The laser-one hazard detector system, used on the Rensselaer Mars rover, is reviewed briefly with respect to the hardware subsystems, the operation, and the results obtained. A multidetector scanning system was designed to improve on the original system. Interactive support software was designed and programmed to implement real time control of the rover or platform with the elevation scanning mast. The formats of both the raw data and the post-run data files were selected. In addition, the interface requirements were selected and some initial hardware-software testing was completed.

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

    PubMed

    Pietropaolo, A; Gorini, G; Festa, G; Andreani, C; De Pascale, M P; Reali, E; Grazzi, F; Schooneveld, E M

    2009-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  9. Multi-Gap Resistive Plate - New Type of Detector for Time of Flight

    NASA Astrophysics Data System (ADS)

    Wu, J.; Wang, X. L.

    2005-04-01

    A Time-of-Flight tray with 28 6-gap MRPC modules was tested at AGS and then installed in STAR for the RHIC 2003 physics run after a series of module R&D. Results show clear identification of K/π up to 1.6 GeV/c and proton/K up to 2.9 GeV/c. In addition, electrons can be clearly identified by combining the dE/dx information from the TPC with the TOF detector.

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

    SciTech Connect

    Pietropaolo, A.; Gorini, G.; Festa, G.; Andreani, C.; De Pascale, M. P.; Reali, E.; Grazzi, F.; Schooneveld, E. M.

    2009-09-15

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

  11. Time dependent 14 MeV neutrons measurement using a polycrystalline chemical vapor deposited diamond detector at the JET tokamak

    SciTech Connect

    Angelone, M.; Pillon, M.; Bertalot, L.; Orsitto, F.; Marinelli, M.; Milani, E.; Pucella, G.; Tucciarone, A.; Verona-Rinati, G.; Popovichev, S.; Murari, A.

    2005-01-01

    A polycrystalline chemical vapor deposited (CVD) diamond detector was installed on a JET tokamak in order to monitor the time dependent 14 MeV neutron emission produced by D-T plasma pulses during the Trace Tritium Experiment (TTE) performed in October 2003. This was the first tentative ever attempted to use a CVD diamond detector as neutron monitor in a tokamak environment. Despite its small active volume, the detector was able to detect the 14 MeV neutron emission (>1.0x10{sup 15} n/shot) with good reliability and stability during the experimental campaign that lasted five weeks. The comparison with standard silicon detectors presently used at JET as 14 MeV neutron monitors is reported, showing excellent correlation between the measurements. The results prove that CVD diamond detectors can be reliably used in a tokamak environment and therefore confirm the potential of this technology for next step machines like ITER.

  12. Investigating ion-surface collisions with a niobium superconducting tunnel junction detector in a time-of-flight mass spectrometer

    SciTech Connect

    Westmacott, G.; Zhong, F.; Frank, M.; Friedrich, S.; Labov, S.; Benner, W.H.

    1999-12-01

    The performance of an energy sensitive, niobium superconducting tunnel junction detector is investigated by measuring the pulse height produced by impacting molecular and atomic ions at different kinetic energies. Ions are produced by laser resorption and matrix-assisted laser desorption in a time-of-flight mass spectrometer. Results show that the STJ detector pulse height decreases for increasing molecular ion mass, passes through a minimum at around 2000 Da, and the increases with increasing mass of molecular ions above 2000Da. The detector does not show a decline in sensitivity for high mass ions as is observed with microchannel plate ion detectors. These detector plus height measurements are discussed in terms of several physical mechanisms involved in an ion-surface collision.

  13. Dynamic Engagement of Human Motion Detectors across Space–Time Coordinates

    PubMed Central

    2014-01-01

    Motion detection is a fundamental property of the visual system. The gold standard for studying and understanding this function is the motion energy model. This computational tool relies on spatiotemporally selective filters that capture the change in spatial position over time afforded by moving objects. Although the filters are defined in space–time, their human counterparts have never been studied in their native spatiotemporal space but rather in the corresponding frequency domain. When this frequency description is back-projected to spatiotemporal description, not all characteristics of the underlying process are retained, leaving open the possibility that important properties of human motion detection may have remained unexplored. We derived descriptors of motion detectors in native space–time, and discovered a large unexpected dynamic structure involving a >2× change in detector amplitude over the first ∼100 ms. This property is not predicted by the energy model, generalizes across the visual field, and is robust to adaptation; however, it is silenced by surround inhibition and is contrast dependent. We account for all results by extending the motion energy model to incorporate a small network that supports feedforward spread of activation along the motion trajectory via a simple gain-control circuit. PMID:24948800

  14. Dynamic engagement of human motion detectors across space-time coordinates.

    PubMed

    Neri, Peter

    2014-06-18

    Motion detection is a fundamental property of the visual system. The gold standard for studying and understanding this function is the motion energy model. This computational tool relies on spatiotemporally selective filters that capture the change in spatial position over time afforded by moving objects. Although the filters are defined in space-time, their human counterparts have never been studied in their native spatiotemporal space but rather in the corresponding frequency domain. When this frequency description is back-projected to spatiotemporal description, not all characteristics of the underlying process are retained, leaving open the possibility that important properties of human motion detection may have remained unexplored. We derived descriptors of motion detectors in native space-time, and discovered a large unexpected dynamic structure involving a >2× change in detector amplitude over the first ∼100 ms. This property is not predicted by the energy model, generalizes across the visual field, and is robust to adaptation; however, it is silenced by surround inhibition and is contrast dependent. We account for all results by extending the motion energy model to incorporate a small network that supports feedforward spread of activation along the motion trajectory via a simple gain-control circuit. Copyright © 2014 the authors 0270-6474/14/348449-13$15.00/0.

  15. Using standard calibrated geometries to characterize a coaxial high purity germanium gamma detector for Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    van der Graaf, E. R.; Dendooven, P.; Brandenburg, S.

    2014-06-01

    A detector model optimization procedure based on matching Monte Carlo simulations with measurements for two experimentally calibrated sample geometries which are frequently used in radioactivity measurement laboratories results in relative agreement within 5% between simulated and measured efficiencies for a high purity germanium detector. The optimization procedure indicated that the increase in dead layer thickness is largely responsible for a detector efficiency decrease in time. The optimized detector model allows Monte Carlo efficiency calibration for all other samples of which the geometry and bulk composition is known. The presented method is a competitive and economic alternative to more elaborate detector scanning methods and results in a comparable accuracy.

  16. Using standard calibrated geometries to characterize a coaxial high purity germanium gamma detector for Monte Carlo simulations.

    PubMed

    van der Graaf, E R; Dendooven, P; Brandenburg, S

    2014-06-01

    A detector model optimization procedure based on matching Monte Carlo simulations with measurements for two experimentally calibrated sample geometries which are frequently used in radioactivity measurement laboratories results in relative agreement within 5% between simulated and measured efficiencies for a high purity germanium detector. The optimization procedure indicated that the increase in dead layer thickness is largely responsible for a detector efficiency decrease in time. The optimized detector model allows Monte Carlo efficiency calibration for all other samples of which the geometry and bulk composition is known. The presented method is a competitive and economic alternative to more elaborate detector scanning methods and results in a comparable accuracy.

  17. Using standard calibrated geometries to characterize a coaxial high purity germanium gamma detector for Monte Carlo simulations

    SciTech Connect

    Graaf, E. R. van der Dendooven, P.; Brandenburg, S.

    2014-06-15

    A detector model optimization procedure based on matching Monte Carlo simulations with measurements for two experimentally calibrated sample geometries which are frequently used in radioactivity measurement laboratories results in relative agreement within 5% between simulated and measured efficiencies for a high purity germanium detector. The optimization procedure indicated that the increase in dead layer thickness is largely responsible for a detector efficiency decrease in time. The optimized detector model allows Monte Carlo efficiency calibration for all other samples of which the geometry and bulk composition is known. The presented method is a competitive and economic alternative to more elaborate detector scanning methods and results in a comparable accuracy.

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

    PubMed

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

    2012-10-01

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

  19. Parallel Configuration For Fast Superconducting Strip Line Detectors With Very Large Area In Time Of Flight Mass Spectrometry

    SciTech Connect

    Casaburi, A.; Zen, N.; Suzuki, K.; Ohkubo, M.; Ejrnaes, M.; Cristiano, R.; Pagano, S.

    2009-12-16

    We realized a very fast and large Superconducting Strip Line Detector based on a parallel configuration of nanowires. The detector with size 200x200 {mu}m{sup 2} recorded a sub-nanosecond pulse width of 700 ps in FWHM (400 ps rise time and 530 ps relaxation time) for lysozyme monomers/multimers molecules accelerated at 175 keV in a Time of Flight Mass Spectrometer. This record is the best in the class of superconducting detectors and comparable with the fastest NbN superconducting single photon detector of 10x10 {mu}m{sup 2}. We succeeded in acquiring mass spectra as the first step for a scale-up to {approx}mm pixel size for high throughput MS analysis, while keeping a fast response.

  20. The Distribution of Neutron Absorbing Time in the Neutron Detector of the GAMMA-400 Space Observatory

    NASA Astrophysics Data System (ADS)

    Gnezdilov, I. I.; Mukhin, V. I.; Demichev, M. A.

    The neutron detectors (ND) have been designed for the future GAMMA-400 space observatory with 3He-counters and 6LiF/ZnS(Ag) scintillation screens. The ND contribution in the rejection factor for protons in the GAMMA-400 is considered with significantly different number of neutrons generated in the electromagnetic and hadronic cascades. The ND is predominantly made from polyethylene, it has sizes of 100×100×10 cm3. GEANT4 simulation was obtained by the differential distribution of neutron absorbing time as the function of the registration time for different 3He, 6Li concentration. Nomograms were constructed for determining neutrons miscount depending on the number of neutrons crossing the ND and time resolution of the ND. The simulation results showed that the ND with 33 3He-counters detected the neutron fluence 0.23 n/cm2 without neutrons miscount.

  1. Dead sea water intoxication.

    PubMed

    Levy-Khademi, Floris; Brooks, Rebecca; Maayan, Channa; Tenenbaum, Ariel; Wexler, Isaiah D

    2012-08-01

    Near drowning in the Dead Sea is associated with both respiratory manifestations and severe electrolyte abnormalities. It is often difficult to distinguish between the contributions of sea water aspiration or ingestion to clinical manifestations. We present a unique case of accidental ingestion of a large amount of Dead Sea water through a gastrostomy tube in which a patient with familial dysautonomia presented with severe electrolyte disturbances. Forced diuresis with large amounts of intravenous fluids resulted in clinical and biochemical improvement. Full recovery was achieved after 2 days of treatment.

  2. "Living versus Dead":

    PubMed Central

    Chakrabarti, Pratik

    2010-01-01

    Summary The Semple antirabies vaccine was developed by David Semple in India in 1911. Semple introduced a peculiarly British approach within the Pasteurian tradition by using carbolized dead virus. This article studies this unique phase of vaccine research between 1910 and 1935 to show that in the debates and laboratory experiments around the potency and safety of vaccines, categories like "living" and "dead" were often used as ideological and moral denominations. These abstract and ideological debates were crucial in defining the final configuration of the Semple vaccine, the most popular antirabies vaccine used globally, and also in shaping international vaccination policies. PMID:21037397

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

    SciTech Connect

    Schmid, G J; Friensehner, A F; Glebov, V Y; Hargrove, D R; Hatchett, S P; Izumi, N; Lerche, R A; Phillips, T W; Sangster, T C; Sibernagel, C; Stoeckl, C

    2001-06-19

    As part of a laser fusion diagnostic development program, we have performed pulsed neutron and pulsed laser tests of a CVD diamond detector manufactured from DIAFILM, a commercial grade of CVD diamond. The laser tests were performed at the short pulse UV laser at Bechtel Nevada in Livermore, CA. The pulsed neutrons were provided by DT capsule implosions at the OMEGA laser fusion facility in Rochester, NY. From these tests, we have determined the impulse response to be 250 ps fwhm for an applied E-field of 500 V/mm. Additionally, we have determined the sensitivity to be 2.8 mA/W at 500 V/mm and 4.5 mA/W at 1000 V/mm (2 to 6x times higher than reported values for natural Type IIa diamond). These detector characteristics allow us to conceive of a neutron time-of-flight current mode spectrometer based on CVD diamond. Such an instrument would sit inside the laser fusion target chamber close to TCC, and would record neutron spectra fast enough such that backscattered neutrons and y rays from the target chamber wall would not be a concern. However, the data we have taken show that the Electromagnetic Pulse (EMP) noise could be a limiting factor in performance. Determining the degree to which this noise can be shielded will be an important subject of future tests.

  4. Development of an integrated four-channel fast avalanche-photodiode detector system with nanosecond time resolution

    NASA Astrophysics Data System (ADS)

    Li, Zhenjie; Li, Qiuju; Chang, Jinfan; Ma, Yichao; Liu, Peng; Wang, Zheng; Hu, Michael Y.; Zhao, Jiyong; Alp, E. E.; Xu, Wei; Tao, Ye; Wu, Chaoqun; Zhou, Yangfan

    2017-10-01

    A four-channel nanosecond time-resolved avalanche-photodiode (APD) detector system is developed at Beijing Synchrotron Radiation. It uses a single module for signal processing and readout. This integrated system provides better reliability and flexibility for custom improvement. The detector system consists of three parts: (i) four APD sensors, (ii) four fast preamplifiers and (iii) a time-digital-converter (TDC) readout electronics. The C30703FH silicon APD chips fabricated by Excelitas are used as the sensors of the detectors. It has an effective light-sensitive area of 10 × 10 mm2 and an absorption layer thickness of 110 μm. A fast preamplifier with a gain of 59 dB and bandwidth of 2 GHz is designed to readout of the weak signal from the C30703FH APD. The TDC is realized by a Spartan-6 field-programmable-gate-array (FPGA) with multiphase method in a resolution of 1ns. The arrival time of all scattering events between two start triggers can be recorded by the TDC. The detector has been used for nuclear resonant scattering study at both Advanced Photon Source and also at Beijing Synchrotron Radiation Facility. For the X-ray energy of 14.4 keV, the time resolution, the full width of half maximum (FWHM) of the detector (APD sensor + fast amplifier) is 0.86 ns, and the whole detector system (APD sensors + fast amplifiers + TDC readout electronics) achieves a time resolution of 1.4 ns.

  5. Time-Encoded Thermal Neutron Imaging Using Large-Volume Pixelated CdZnTe Detectors

    NASA Astrophysics Data System (ADS)

    Brown, Steven T.

    CdZnTe detectors are commonly used for room-temperature gamma-ray spectroscopy and imaging in a variety of applications including nuclear security, nuclear medicine, and space science. The material's long-established sensitivity to thermal neutrons, however, is less utilized. Generally speaking, the performance of neutron detectors based on the Cd capture reaction is limited by the physical nature of the reaction itself. Multiple gamma rays are emitted promptly following each capture event, which consists of one realization of many possible combinations of gamma-ray lines. Although the gamma-ray cascade can reduce photopeak efficiency in conventional devices, this work demonstrates that pixelated CdZnTe can recover losses by reading out each gamma-ray interaction separately. Including coincident events, the measured 558-keV photopeak efficiency for a 3 x 3 array of 2 cm x 2 cm by 1.5 cm pixelated CdZnTe detectors was about 10%, i.e., ten 558 keV photopeak events per 100 incident thermal neutrons. This was in good agreement with its calculated value. Initial measurements also show that neutron-gamma discrimination beyond simple energy windowing is possible when incorporating the 3-D interaction locations of gamma rays provided by the pixelated readout. In this work, we developed and successfully demonstrated a proof-of-principle time-encoding system for thermal neutron imaging using pixelated CdZnTe. Time encoding was chosen because it is not limited by the detector's position resolution or spatial extent. These issues are exacerbated by Cd capture due to the dispersal of cascade gamma rays throughout the device. The system was first tested using a MURA-based, W-metal mask with both Co-57 and U-metal gamma-ray sources. About 0.3° angular resolution within a 22° field of view was achieved for gamma rays, and good image uniformity was observed for objects of moderate spatial extent. A MURA-based thermal neutron mask was then constructed using 1-mm-thick BN tiles

  6. Standardization of (166m)Ho and 243Am/239Np by live-timed anti-coincidence counting with extending dead time.

    PubMed

    da Silva, C J; Loureiro, J S; Delgado, J U; Poledna, R; Moreira, D S; Iwahara, A; Tauhata, L; da Silva, R L; Lopes, R T

    2012-09-01

    The National Laboratory for Metrology of Ionizing Radiation (LNMRI)/Brazil acquired (166m)Ho and (243)Am/(239)Np solutions from commercial suppliers in order to realize primary standardization and therefore reducing the associated uncertainties. The method used in the standardization was the live-timed 4πβ(LS)-γ(ΝaI(Tl)) anticoincidence counting. The live-timed anticoincidence system is operated since 2006 in LNMRI and is composed of two MTR2 modules donated by Laboratoire National Henri Becquerel (LNE-LNHB)/France. The data acquisition system uses a homemade LabView program and an Excel file for calculus. These systems have been used for primary standardization at LNMRI for many radionuclides and recently took part in the (124)Sb and (177)Lu International Key Comparisons with good performance. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. 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.

  8. Fusion neutron detector for time-of-flight measurements in z-pinch and plasma focus experiments

    SciTech Connect

    Klir, D.; Kravarik, J.; Kubes, P.; Rezac, K.; Litseva, E.; Tomaszewski, K.; Karpinski, L.; Paduch, M.; Scholz, M.

    2011-03-15

    We have developed and tested sensitive neutron detectors for neutron time-of-flight measurements in z-pinch and plasma focus experiments with neutron emission times in tens of nanoseconds and with neutron yields between 10{sup 6} and 10{sup 12} per one shot. The neutron detectors are composed of a BC-408 fast plastic scintillator and Hamamatsu H1949-51 photomultiplier tube (PMT). During the calibration procedure, a PMT delay was determined for various operating voltages. The temporal resolution of the neutron detector was measured for the most commonly used PMT voltage of 1.4 kV. At the PF-1000 plasma focus, a novel method of the acquisition of a pulse height distribution has been used. This pulse height analysis enabled to determine the single neutron sensitivity for various neutron energies and to calibrate the neutron detector for absolute neutron yields at about 2.45 MeV.

  9. Particle identification with the ALICE Time-Of-Flight detector at the LHC

    NASA Astrophysics Data System (ADS)

    Alici, A.

    2014-12-01

    High performance Particle Identification system (PID) is a distinguishing characteristic of the ALICE experiment at the CERN Large Hadron Collider (LHC). Charged particles in the intermediate momentum range are identified in ALICE by the Time-Of-Flight (TOF) detector. The TOF exploits the Multi-gap Resistive Plate Chamber (MRPC) technology, capable of an intrinsic time resolution at the level of few tens of ps with an overall efficiency close to 100% and a large operation plateau. The full system is made of 1593 MRPC chambers with a total area of 141 m2, covering the pseudorapidity interval [-0.9,+0.9] and the full azimuthal angle. The ALICE TOF system has shown very stable operation during the first 3 years of collisions at the LHC. In this paper a summary of the system performance as well as main results with data from collisions will be reported.

  10. A system for accurate and automated injection of hyperpolarized substrate with minimal dead time and scalable volumes over a large range.

    PubMed

    Reynolds, Steven; Bucur, Adriana; Port, Michael; Alizadeh, Tooba; Kazan, Samira M; Tozer, Gillian M; Paley, Martyn N J

    2014-02-01

    Over recent years hyperpolarization by dissolution dynamic nuclear polarization has become an established technique for studying metabolism in vivo in animal models. Temporal signal plots obtained from the injected metabolite and daughter products, e.g. pyruvate and lactate, can be fitted to compartmental models to estimate kinetic rate constants. Modeling and physiological parameter estimation can be made more robust by consistent and reproducible injections through automation. An injection system previously developed by us was limited in the injectable volume to between 0.6 and 2.4ml and injection was delayed due to a required syringe filling step. An improved MR-compatible injector system has been developed that measures the pH of injected substrate, uses flow control to reduce dead volume within the injection cannula and can be operated over a larger volume range. The delay time to injection has been minimized by removing the syringe filling step by use of a peristaltic pump. For 100μl to 10.000ml, the volume range typically used for mice to rabbits, the average delivered volume was 97.8% of the demand volume. The standard deviation of delivered volumes was 7μl for 100μl and 20μl for 10.000ml demand volumes (mean S.D. was 9 ul in this range). In three repeat injections through a fixed 0.96mm O.D. tube the coefficient of variation for the area under the curve was 2%. For in vivo injections of hyperpolarized pyruvate in tumor-bearing rats, signal was first detected in the input femoral vein cannula at 3-4s post-injection trigger signal and at 9-12s in tumor tissue. The pH of the injected pyruvate was 7.1±0.3 (mean±S.D., n=10). For small injection volumes, e.g. less than 100μl, the internal diameter of the tubing contained within the peristaltic pump could be reduced to improve accuracy. Larger injection volumes are limited only by the size of the receiving vessel connected to the pump.

  11. A system for accurate and automated injection of hyperpolarized substrate with minimal dead time and scalable volumes over a large range☆

    PubMed Central

    Reynolds, Steven; Bucur, Adriana; Port, Michael; Alizadeh, Tooba; Kazan, Samira M.; Tozer, Gillian M.; Paley, Martyn N.J.

    2014-01-01

    Over recent years hyperpolarization by dissolution dynamic nuclear polarization has become an established technique for studying metabolism in vivo in animal models. Temporal signal plots obtained from the injected metabolite and daughter products, e.g. pyruvate and lactate, can be fitted to compartmental models to estimate kinetic rate constants. Modeling and physiological parameter estimation can be made more robust by consistent and reproducible injections through automation. An injection system previously developed by us was limited in the injectable volume to between 0.6 and 2.4 ml and injection was delayed due to a required syringe filling step. An improved MR-compatible injector system has been developed that measures the pH of injected substrate, uses flow control to reduce dead volume within the injection cannula and can be operated over a larger volume range. The delay time to injection has been minimized by removing the syringe filling step by use of a peristaltic pump. For 100 μl to 10.000 ml, the volume range typically used for mice to rabbits, the average delivered volume was 97.8% of the demand volume. The standard deviation of delivered volumes was 7 μl for 100 μl and 20 μl for 10.000 ml demand volumes (mean S.D. was 9 ul in this range). In three repeat injections through a fixed 0.96 mm O.D. tube the coefficient of variation for the area under the curve was 2%. For in vivo injections of hyperpolarized pyruvate in tumor-bearing rats, signal was first detected in the input femoral vein cannula at 3–4 s post-injection trigger signal and at 9–12 s in tumor tissue. The pH of the injected pyruvate was 7.1 ± 0.3 (mean ± S.D., n = 10). For small injection volumes, e.g. less than 100 μl, the internal diameter of the tubing contained within the peristaltic pump could be reduced to improve accuracy. Larger injection volumes are limited only by the size of the receiving vessel connected to the pump. PMID:24355621

  12. A system for accurate and automated injection of hyperpolarized substrate with minimal dead time and scalable volumes over a large range

    NASA Astrophysics Data System (ADS)

    Reynolds, Steven; Bucur, Adriana; Port, Michael; Alizadeh, Tooba; Kazan, Samira M.; Tozer, Gillian M.; Paley, Martyn N. J.

    2014-02-01

    Over recent years hyperpolarization by dissolution dynamic nuclear polarization has become an established technique for studying metabolism in vivo in animal models. Temporal signal plots obtained from the injected metabolite and daughter products, e.g. pyruvate and lactate, can be fitted to compartmental models to estimate kinetic rate constants. Modeling and physiological parameter estimation can be made more robust by consistent and reproducible injections through automation. An injection system previously developed by us was limited in the injectable volume to between 0.6 and 2.4 ml and injection was delayed due to a required syringe filling step. An improved MR-compatible injector system has been developed that measures the pH of injected substrate, uses flow control to reduce dead volume within the injection cannula and can be operated over a larger volume range. The delay time to injection has been minimized by removing the syringe filling step by use of a peristaltic pump. For 100 μl to 10.000 ml, the volume range typically used for mice to rabbits, the average delivered volume was 97.8% of the demand volume. The standard deviation of delivered volumes was 7 μl for 100 μl and 20 μl for 10.000 ml demand volumes (mean S.D. was 9 ul in this range). In three repeat injections through a fixed 0.96 mm O.D. tube the coefficient of variation for the area under the curve was 2%. For in vivo injections of hyperpolarized pyruvate in tumor-bearing rats, signal was first detected in the input femoral vein cannula at 3-4 s post-injection trigger signal and at 9-12 s in tumor tissue. The pH of the injected pyruvate was 7.1 ± 0.3 (mean ± S.D., n = 10). For small injection volumes, e.g. less than 100 μl, the internal diameter of the tubing contained within the peristaltic pump could be reduced to improve accuracy. Larger injection volumes are limited only by the size of the receiving vessel connected to the pump.

  13. Dusty Dead Star

    NASA Image and Video Library

    2010-03-29

    A composite image from NASA Chandra and Spitzer space telescopes shows the dusty remains of a collapsed star, a supernova remnant called G54.1+0.3. The white source at the center is a dead star called a pulsar.

  14. A fast preamplifier concept for SiPM-based time-of-flight PET detectors

    NASA Astrophysics Data System (ADS)

    Huizenga, J.; Seifert, S.; Schreuder, F.; van Dam, H. T.; Dendooven, P.; Löhner, H.; Vinke, R.; Schaart, D. R.

    2012-12-01

    Silicon photomultipliers (SiPMs) offer high gain and fast response to light, making them interesting for fast timing applications such as time-of-flight (TOF) PET. To fully exploit the potential of these photosensors, dedicated preamplifiers that do not deteriorate the rise time and signal-to-noise ratio are crucial. Challenges include the high sensor capacitance, typically >300 pF for a 3 mm×3 mm SiPM sensor, as well as oscillation issues. Here we present a preamplifier concept based on low noise, high speed transistors, designed for optimum timing performance. The input stage consists of a transimpedance common-base amplifier with a very low input impedance even at high frequencies, which assures a good linearity and avoids that the high detector capacitance affects the amplifier bandwidth. The amplifier has a fast timing output as well as a 'slow' energy output optimized for determining the total charge content of the pulse. The rise time of the amplifier is about 300 ps. The measured coincidence resolving time (CRT) for 511 keV photon pairs using the amplifiers in combination with 3 mm×3 mm SiPMs (Hamamatsu MPPC-S10362-33-050C) coupled to 3 mm×3 mm×5 mm LaBr3:Ce and LYSO:Ce crystals equals 95 ps FWHM and 138 ps FWHM, respectively.

  15. Radiation hardness and precision timing study of silicon detectors for the CMS High Granularity Calorimeter (HGC)

    NASA Astrophysics Data System (ADS)

    Currás, Esteban; Fernández, Marcos; Gallrapp, Christian; Gray, Lindsey; Mannelli, Marcello; Meridiani, Paolo; Moll, Michael; Nourbakhsh, Shervin; Scharf, Christian; Silva, Pedro; Steinbrueck, Georg; Fatis, Tommaso Tabarelli de; Vila, Iván

    2017-02-01

    The high luminosity upgraded LHC or Phase-II is expected to increase the instantaneous luminosity by a factor of 10 beyond the LHC's design value, expecting to deliver 250 fb-1 per year for a further 10 years of operation. Under these conditions the performance degradation due to integrated radiation dose will need to be addressed. The CMS collaboration is planning to upgrade the forward calorimeters. The replacement is called the High Granularity Calorimeter (HGC) and it will be realized as a sampling calorimeter with layers of silicon detectors interleaved. The sensors will be realized as pad detectors with sizes of less that ∼1.0 cm2 and an active thickness between 100 and 300 μm depending on the position, respectively, the expected radiation levels. For an integrated luminosity of 3000 fb-1, the electromagnetic calorimetry will sustain integrated doses of 1.5 MGy (150 Mrads) and neutron fluences up to 1016 neq/cm2. A radiation tolerance study after neutron irradiation of 300, 200, and 100 μm n-on-p and p-on-n silicon pads irradiated to fluences up to 1.6×1016 neq/cm2 is presented. The properties of these diodes studied before and after irradiation were leakage current, capacitance, charge collection efficiency, annealing effects and timing capability. The results of these measurements validate these sensors as candidates for the HGC system.

  16. CMOS detector arrays in a virtual 10-kilopixel camera for coherent terahertz real-time imaging.

    PubMed

    Boppel, Sebastian; Lisauskas, Alvydas; Max, Alexander; Krozer, Viktor; Roskos, Hartmut G

    2012-02-15

    We demonstrate the principle applicability of antenna-coupled complementary metal oxide semiconductor (CMOS) field-effect transistor arrays as cameras for real-time coherent imaging at 591.4 GHz. By scanning a few detectors across the image plane, we synthesize a focal-plane array of 100×100 pixels with an active area of 20×20 mm2, which is applied to imaging in transmission and reflection geometries. Individual detector pixels exhibit a voltage conversion loss of 24 dB and a noise figure of 41 dB for 16 μW of the local oscillator (LO) drive. For object illumination, we use a radio-frequency (RF) source with 432 μW at 590 GHz. Coherent detection is realized by quasioptical superposition of the image and the LO beam with 247 μW. At an effective frame rate of 17 Hz, we achieve a maximum dynamic range of 30 dB in the center of the image and more than 20 dB within a disk of 18 mm diameter. The system has been used for surface reconstruction resolving a height difference in the μm range.

  17. Dead Star Rumbles

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Composite of Supernova Remnant Cassiopeia A This Spitzer Space Telescope composite shows the supernova remnant Cassiopeia A (white ball) and surrounding clouds of dust (gray, orange and blue). It consists of two processed images taken one year apart. Dust features that have not changed over time appear gray, while those that have changed are colored blue or orange. Blue represents an earlier time and orange, a later time.

    These observations illustrate that a blast of light from Cassiopeia A is waltzing outward through the dusty skies. This dance, called an 'infrared echo,' began when the remnant erupted about 50 years ago.

    Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion 325 years ago. It consists of a dead star, called a neutron star, and a surrounding shell of material that was blasted off as the star died. This remnant is located 10,000 light-years away in the northern constellation Cassiopeia.

    An infrared echo is created when a star explodes or erupts, flashing light into surrounding clumps of dust. As the light zips through the dust clumps, it heats them up, causing them to glow successively in infrared, like a chain of Christmas bulbs lighting up one by one. The result is an optical illusion, in which the dust appears to be flying outward at the speed of light. This apparent motion can be seen here by the shift in colored dust clumps.

    Echoes are distinct from supernova shockwaves, which are made up material that is swept up and hurled outward by exploding stars.

    This infrared echo is the largest ever seen, stretching more than 50 light-years away from Cassiopeia A. If viewed from Earth, the entire movie frame would take up the same amount of space as two full moons.

    Hints of an older infrared echo from Cassiopeia A's supernova explosion hundreds of years ago can also be seen.

    The earlier Spitzer image was taken on November 30

  18. Dead Star Rumbles

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Composite of Supernova Remnant Cassiopeia A This Spitzer Space Telescope composite shows the supernova remnant Cassiopeia A (white ball) and surrounding clouds of dust (gray, orange and blue). It consists of two processed images taken one year apart. Dust features that have not changed over time appear gray, while those that have changed are colored blue or orange. Blue represents an earlier time and orange, a later time.

    These observations illustrate that a blast of light from Cassiopeia A is waltzing outward through the dusty skies. This dance, called an 'infrared echo,' began when the remnant erupted about 50 years ago.

    Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion 325 years ago. It consists of a dead star, called a neutron star, and a surrounding shell of material that was blasted off as the star died. This remnant is located 10,000 light-years away in the northern constellation Cassiopeia.

    An infrared echo is created when a star explodes or erupts, flashing light into surrounding clumps of dust. As the light zips through the dust clumps, it heats them up, causing them to glow successively in infrared, like a chain of Christmas bulbs lighting up one by one. The result is an optical illusion, in which the dust appears to be flying outward at the speed of light. This apparent motion can be seen here by the shift in colored dust clumps.

    Echoes are distinct from supernova shockwaves, which are made up material that is swept up and hurled outward by exploding stars.

    This infrared echo is the largest ever seen, stretching more than 50 light-years away from Cassiopeia A. If viewed from Earth, the entire movie frame would take up the same amount of space as two full moons.

    Hints of an older infrared echo from Cassiopeia A's supernova explosion hundreds of years ago can also be seen.

    The earlier Spitzer image was taken on November 30

  19. Barrel time-of-flight detector for the PANDA experiment at FAIR

    NASA Astrophysics Data System (ADS)

    Gruber, L.; Brunner, S. E.; Marton, J.; Orth, H.; Suzuki, K.

    2016-07-01

    The barrel time-of-flight detector for the PANDA experiment at FAIR is foreseen as a Scintillator Tile (SciTil) Hodoscope based on several thousand small plastic scintillator tiles read-out with directly attached Silicon Photomultipliers (SiPMs). The main tasks of the system are an accurate determination of the time origin of particle tracks to avoid event mixing at high collision rates, relative time-of-flight measurements as well as particle identification in the low momentum regime. The main requirements are the use of a minimum material amount and a time resolution of σ < 100 ps. We have performed extensive optimization studies and prototype tests to prove the feasibility of the SciTil design and finalize the R&D phase. In a 2.7 GeV/c proton beam at Forschungszentrum Jülich a time resolution of about 80 ps has been achieved using SiPMs from KETEK and Hamamatsu with an active area of 3 × 3mm2. Employing the Digital Photon Counter from Philips a time resolution of about 30 ps has been reached.

  20. A generic FPGA-based detector readout and real-time image processing board

    NASA Astrophysics Data System (ADS)

    Sarpotdar, Mayuresh; Mathew, Joice; Safonova, Margarita; Murthy, Jayant

    2016-07-01

    For space-based astronomical observations, it is important to have a mechanism to capture the digital output from the standard detector for further on-board analysis and storage. We have developed a generic (application- wise) field-programmable gate array (FPGA) board to interface with an image sensor, a method to generate the clocks required to read the image data from the sensor, and a real-time image processor system (on-chip) which can be used for various image processing tasks. The FPGA board is applied as the image processor board in the Lunar Ultraviolet Cosmic Imager (LUCI) and a star sensor (StarSense) - instruments developed by our group. In this paper, we discuss the various design considerations for this board and its applications in the future balloon and possible space flights.

  1. A combined time-of-flight and depth-of-interaction detector for total-body positron emission tomography

    SciTech Connect

    Berg, Eric Roncali, Emilie; Du, Junwei; Cherry, Simon R.; Kapusta, Maciej

    2016-02-15

    Purpose: In support of a project to build a total-body PET scanner with an axial field-of-view of 2 m, the authors are developing simple, cost-effective block detectors with combined time-of-flight (TOF) and depth-of-interaction (DOI) capabilities. Methods: This work focuses on investigating the potential of phosphor-coated crystals with conventional PMT-based block detector readout to provide DOI information while preserving timing resolution. The authors explored a variety of phosphor-coating configurations with single crystals and crystal arrays. Several pulse shape discrimination techniques were investigated, including decay time, delayed charge integration (DCI), and average signal shapes. Results: Pulse shape discrimination based on DCI provided the lowest DOI positioning error: 2 mm DOI positioning error was obtained with single phosphor-coated crystals while 3–3.5 mm DOI error was measured with the block detector module. Minimal timing resolution degradation was observed with single phosphor-coated crystals compared to uncoated crystals, and a timing resolution of 442 ps was obtained with phosphor-coated crystals in the block detector compared to 404 ps without phosphor coating. Flood maps showed a slight degradation in crystal resolvability with phosphor-coated crystals; however, all crystals could be resolved. Energy resolution was degraded by 3%–7% with phosphor-coated crystals compared to uncoated crystals. Conclusions: These results demonstrate the feasibility of obtaining TOF–DOI capabilities with simple block detector readout using phosphor-coated crystals.

  2. A combined time-of-flight and depth-of-interaction detector for total-body positron emission tomography

    PubMed Central

    Berg, Eric; Roncali, Emilie; Kapusta, Maciej; Du, Junwei; Cherry, Simon R.

    2016-01-01

    Purpose: In support of a project to build a total-body PET scanner with an axial field-of-view of 2 m, the authors are developing simple, cost-effective block detectors with combined time-of-flight (TOF) and depth-of-interaction (DOI) capabilities. Methods: This work focuses on investigating the potential of phosphor-coated crystals with conventional PMT-based block detector readout to provide DOI information while preserving timing resolution. The authors explored a variety of phosphor-coating configurations with single crystals and crystal arrays. Several pulse shape discrimination techniques were investigated, including decay time, delayed charge integration (DCI), and average signal shapes. Results: Pulse shape discrimination based on DCI provided the lowest DOI positioning error: 2 mm DOI positioning error was obtained with single phosphor-coated crystals while 3–3.5 mm DOI error was measured with the block detector module. Minimal timing resolution degradation was observed with single phosphor-coated crystals compared to uncoated crystals, and a timing resolution of 442 ps was obtained with phosphor-coated crystals in the block detector compared to 404 ps without phosphor coating. Flood maps showed a slight degradation in crystal resolvability with phosphor-coated crystals; however, all crystals could be resolved. Energy resolution was degraded by 3%–7% with phosphor-coated crystals compared to uncoated crystals. Conclusions: These results demonstrate the feasibility of obtaining TOF–DOI capabilities with simple block detector readout using phosphor-coated crystals. PMID:26843254

  3. A combined time-of-flight and depth-of-interaction detector for total-body positron emission tomography.

    PubMed

    Berg, Eric; Roncali, Emilie; Kapusta, Maciej; Du, Junwei; Cherry, Simon R

    2016-02-01

    In support of a project to build a total-body PET scanner with an axial field-of-view of 2 m, the authors are developing simple, cost-effective block detectors with combined time-of-flight (TOF) and depth-of-interaction (DOI) capabilities. This work focuses on investigating the potential of phosphor-coated crystals with conventional PMT-based block detector readout to provide DOI information while preserving timing resolution. The authors explored a variety of phosphor-coating configurations with single crystals and crystal arrays. Several pulse shape discrimination techniques were investigated, including decay time, delayed charge integration (DCI), and average signal shapes. Pulse shape discrimination based on DCI provided the lowest DOI positioning error: 2 mm DOI positioning error was obtained with single phosphor-coated crystals while 3-3.5 mm DOI error was measured with the block detector module. Minimal timing resolution degradation was observed with single phosphor-coated crystals compared to uncoated crystals, and a timing resolution of 442 ps was obtained with phosphor-coated crystals in the block detector compared to 404 ps without phosphor coating. Flood maps showed a slight degradation in crystal resolvability with phosphor-coated crystals; however, all crystals could be resolved. Energy resolution was degraded by 3%-7% with phosphor-coated crystals compared to uncoated crystals. These results demonstrate the feasibility of obtaining TOF-DOI capabilities with simple block detector readout using phosphor-coated crystals.

  4. EMCCD-Based Detector for Time-Resolved X-Ray Diffraction and Scattering Studies of Biological Specimens

    SciTech Connect

    Nagarkar, Vivek V.; Singh, Bipin; Guo, Liang; Gore, David; Irving, Thomas C.

    2007-11-26

    Third generation synchrotron sources such as the Advanced Photon Source (APS), Argonne, IL, are outstanding tools for X-ray diffraction and scattering studies of non-crystalline biological materials. However, these studies are hindered by the lack of detectors that provide multiple frames of detailed structural information on the millisecond time scale at the required high spatial resolution, and large active areas. Here we report the development of a cost effective detector for time-resolved small angle X-ray scattering (SAXS) using a cooled, fiberoptically coupled electron multiplying CCD (EMCCD), whose internal gain is selectable in real-time. The performance of the detector was evaluated using a Gd{sub 2}O{sub 2}S:Tb scintillator and was compared to a current state-of-the-art SAXS detector developed at Brandeis University. We also report our first results on the fabrication of a novel, microcolumnar, ZnSe(Te) scintillator that has a promise to provide very high emission efficiency of over 100,000 photons/MeV, high spatial resolution in excess of 10 lp/mm, and a fast decay time with virtually absent afterglow. Development of this scintillator will complement the EMCCD design, permitting the advances of a high spatial and temporal resolution, large area detector for time resolved applications.

  5. First characterization of a digital SiPM based time-of-flight PET detector with 1 mm spatial resolution.

    PubMed

    Seifert, Stefan; van der Lei, Gerben; van Dam, Herman T; Schaart, Dennis R

    2013-05-07

    Monolithic scintillator detectors can offer a combination of spatial resolution, energy resolution, timing performance, depth-of-interaction information, and detection efficiency that make this type of detector a promising candidate for application in clinical, time-of-flight (TOF) positron emission tomography (PET). In such detectors the scintillation light is distributed over a relatively large number of photosensor pixels and the light intensity per pixel can be relatively low. Therefore, monolithic scintillator detectors are expected to benefit from the low readout noise offered by a novel photosensor called the digital silicon photomultiplier (dSiPM). Here, we present a first experimental characterization of a TOF PET detector comprising a 24 × 24 × 10 mm(3) LSO:Ce,0.2%Ca scintillator read out by a dSiPM array (DPC-6400-44-22) developed by Philips Digital Photon Counting. A spatial resolution of ~1 mm full-width-at-half-maximum (FWHM) averaged over the entire crystal was obtained (varying from just below 1 mm FWHM in the detector center to ~1.2 mm FWHM close to the edges). Furthermore, the bias in the position estimation at the crystal edges that is typically found in monolithic scintillators is well below 1 mm even in the corners of the crystal.

  6. Development of a large-area CMOS-based detector for real-time x-ray imaging

    NASA Astrophysics Data System (ADS)

    Heo, Sung Kyn; Park, Sung Kyu; Hwang, Sung Ha; Im, Dong Ak; Kosonen, Jari; Kim, Tae Woo; Yun, Seungman; Kim, Ho Kyung

    2010-04-01

    Complementary metal-oxide-semiconductor (CMOS) active pixel sensors (APSs) with high electrical and optical performances are now being attractive for digital radiography (DR) and dental cone-beam computed tomography (CBCT). In this study, we report our prototype CMOS-based detectors capable of real-time imaging. The field-of-view of the detector is 12 × 14.4 cm. The detector employs a CsI:Tl scintillator as an x-ray-to-light converter. The electrical performance of the CMOS APS, such as readout noise and full-well capacity, was evaluated. The x-ray imaging characteristics of the detector were evaluated in terms of characteristic curve, pre-sampling modulation transfer function, noise power spectrum, detective quantum efficiency, and image lag. The overall performance of the detector is demonstrated with phantom images obtained for DR and CBCT applications. The detailed development description and measurement results are addressed. With the results, we suggest that the prototype CMOS-based detector has the potential for CBCT and real-time x-ray imaging applications.

  7. Evaluation of a microchannel-plate PMT as a potential timing detector suitable for positron lifetime measurements

    NASA Astrophysics Data System (ADS)

    Kosev, K.; Butterling, M.; Anwand, W.; Cowan, T.; Hartmann, A.; Heidel, K.; Jungmann, M.; Krause-Rehberg, R.; Massarczyk, R.; Schilling, K. D.; Schwengner, R.; Wagner, A.

    2010-12-01

    This paper focuses on the evaluation of a microchannel-plate photomultiplier tube (MCP-PMT) as a candidate detector, suitable for positron lifetime studies. Several properties of MCP-PMTs, such as their fast time response, compact size, low susceptibility to magnetic fields, relatively high gain and the low power consumption make them attractive for positron lifetime spectroscopy. The preliminary tests were performed with a 85001-501 Burle Planacon TM photomultiplier tube assembly. Initial measurements were conducted with a pulsed Picosecond Injection Laser (PiLas) system. The engineering sample of the 85001 exhibits a transit-time-spread (TTS) of 110 ps (FWHM). Further timing experiments showing the suitability of the device as Cherenkov detector are presented. For the first time, a conventional positron lifetime spectrum of a Cz-Si probe measured with a spectrometer, where an MCP-PMT detector is included, has been demonstrated.

  8. Real-time detector for hypervelocity microparticles using piezoelectric material (II)

    NASA Astrophysics Data System (ADS)

    Miyachi, T.; Mdm Team

    This report is concerned with results on response of a piezoelectric lead-zirconate-titanate (PZT) element, by which a possible relation of output waveform to velocity at impact is studied. At first, we point out a meaning of output waveform, in particular, a behavior of the output signal within a few hundred nanoseconds immediately after impact (named as ``first one cycle''), which is free from interference with reflected waves and could contain impact hysteresis. Accordingly, we deal with the first one cycle, and analyze it with respect to its amplitude and frequency components. We obtain the following results: 1. Output amplitude is proportional to the momentum of particles below 6 km/s. 2. Its rise-time is related to the particle velocity above 10km/s. 3. There exists a transition region in between. 4. The sensitivity is confirmed to be independent of the element thickness, contrary to the results in [1,2], in which the amplitude was defined as the maximum peak-to-peak amplitude, which was outside the first one cycle. We propose that a single PZT element can be used as a velocity sensitive detector if the output signal is measured at a sampling rate of ˜ 50MHz. We discuss a PZT detector that is to be employed as a real-time dust monitor to onboard the BepiColombo mission, MDM. This could discriminate real and junk events by analyzing the waveform. [1] T.Miyachi et al., to be published in Adv. Space Rev. ( JASR 6550). [2] T.Miyachi et al., Jpn.J.Appl.Phys.42(2003)1496.

  9. Gallium arsenide strip detectors for particle identification by the triple measurement of time of flight, position and specific ionization

    NASA Astrophysics Data System (ADS)

    Codino, Antonio

    1998-02-01

    A design of a gallium arsenide strip detector performing the triple, simultaneous measurements of position, dE/dx and time of flight is presented (LATIN project). The expected time. energy and position resolutions are given in various experimental conditions. A precursor of this instrument made of silicon strip detectors has been constructed and operated at a temperature of -55° C and tested with a pion beam of 4.0 GeV/c. The measured time resolution is 61±7 ps. Cosmic-ray experiments in space may benefit from this kind of instruments for nuclide and particle identification.

  10. Gallium arsenide strip detectors for particle identification by the triple measurement of time of flight, position and specific ionization

    NASA Astrophysics Data System (ADS)

    Codino, Antonio

    1997-02-01

    A design of a gallium arsenide strip detector performing the triple, simultaneous measurements of position, dE/dx and time of flight is presented (LATIN project). The expected time, energy and position resolutions are given in various experimental conditions. A precursor of this instrument made of silicon strip detectors has been constructed and operated at a temperature of -55 degC and tested with a pion beam of 4.0GeV/c. The measured time resolution is 61+/-7 ps. Cosmic-ray experiments in space may benefit from this kind of instruments for nuclide and particle identification.

  11. Large aperture fast neutron imaging detector with 10-ns time resolution

    NASA Astrophysics Data System (ADS)

    Arikawa, Y.; Matsubara, S.; Abe, Y.; Kato, Y.; Kishimoto, H.; Yogo, A.; Nishimura, H.; Nakai, M.; Shiraga, H.; Fujioka, S.; Azechi, H.; Otake, Y.; Mima, K.; Honda, Y.

    2017-02-01

    Fast neutrons, which are neutrons with energies greater than 1 MeV, are expected to be a source of nondestructive inspection for a large-size infrastructure such as a bridge girder because of their mean free path exceeding the meter. A neutron-imaging device with 10-ns time resolution can discriminate pulsed neutrons from X-rays via time of flight. For this purpose, we require a fast-response neutron imager with large aperture and high image resolution. A neutron-imaging device with time resolution of 10 ns and aperture size of 40 cm × 60 cm was developed. It was filled with fast response liquid scintillator [1] in an aluminum honeycomb plate, which converts neutrons to optical light images. The scintillation light images were relayed using an optical lens and detected using a fast response image intensified CCD. The detector was tested at an electron linear accelerator (LINAC) facility in Osaka University. A short X-ray pulse (30 ps pulse duration) was generated using LINAC, and X-ray radiograph images were obtained with a 10- ns exposure time duration. The radiograph images were well attenuated within 10-ns from the X-ray injection. A high energy X-ray image and a neutron radiograph image of a 30-cm thick concrete block with iron blocks located behind it were successfully observed. This promising technique could facilitate nondestructive inspection of large concrete constructions.

  12. Use of ruthenium dyes for subnanosecond detector fidelity testing in real time transient absorption

    NASA Astrophysics Data System (ADS)

    Byrdin, Martin; Thiagarajan, Viruthachalam; Villette, Sandrine; Espagne, Agathe; Brettel, Klaus

    2009-04-01

    Transient absorption spectroscopy is a powerful tool for the study of photoreactions on time scales from femtoseconds to seconds. Typically, reactions slower than ˜1 ns are recorded by the "classical" technique; the reaction is triggered by an excitation flash, and absorption changes accompanying the reaction are recorded in real time using a continuous monitoring light beam and a detection system with sufficiently fast response. The pico- and femtosecond region can be accessed by the more recent "pump-probe" technique, which circumvents the difficulties of real time detection on a subnanosecond time scale. This is paid for by accumulation of an excessively large number of shots to sample the reaction kinetics. Hence, it is of interest to extend the classical real time technique as far as possible to the subnanosecond range. In order to identify and minimize detection artifacts common on a subnanosecond scale, like overshoot, ringing, and signal reflections, rigorous testing is required of how the detection system responds to fast changes of the monitoring light intensity. Here, we introduce a novel method to create standard signals for detector fidelity testing on a time scale from a few picoseconds to tens of nanoseconds. The signals result from polarized measurements of absorption changes upon excitation of ruthenium complexes {[Ru(bpy)3]2+ and a less symmetric derivative} by a short laser flash. Two types of signals can be created depending on the polarization of the monitoring light with respect to that of the excitation flash: a fast steplike bleaching at magic angle and a monoexponentially decaying bleaching for parallel polarizations. The lifetime of the decay can be easily varied via temperature and viscosity of the solvent. The method is applied to test the performance of a newly developed real time transient absorption setup with 300 ps time resolution and high sensitivity.

  13. Use of ruthenium dyes for subnanosecond detector fidelity testing in real time transient absorption.

    PubMed

    Byrdin, Martin; Thiagarajan, Viruthachalam; Villette, Sandrine; Espagne, Agathe; Brettel, Klaus

    2009-04-01

    Transient absorption spectroscopy is a powerful tool for the study of photoreactions on time scales from femtoseconds to seconds. Typically, reactions slower than approximately 1 ns are recorded by the "classical" technique; the reaction is triggered by an excitation flash, and absorption changes accompanying the reaction are recorded in real time using a continuous monitoring light beam and a detection system with sufficiently fast response. The pico- and femtosecond region can be accessed by the more recent "pump-probe" technique, which circumvents the difficulties of real time detection on a subnanosecond time scale. This is paid for by accumulation of an excessively large number of shots to sample the reaction kinetics. Hence, it is of interest to extend the classical real time technique as far as possible to the subnanosecond range. In order to identify and minimize detection artifacts common on a subnanosecond scale, like overshoot, ringing, and signal reflections, rigorous testing is required of how the detection system responds to fast changes of the monitoring light intensity. Here, we introduce a novel method to create standard signals for detector fidelity testing on a time scale from a few picoseconds to tens of nanoseconds. The signals result from polarized measurements of absorption changes upon excitation of ruthenium complexes {[Ru(bpy)(3)](2+) and a less symmetric derivative} by a short laser flash. Two types of signals can be created depending on the polarization of the monitoring light with respect to that of the excitation flash: a fast steplike bleaching at magic angle and a monoexponentially decaying bleaching for parallel polarizations. The lifetime of the decay can be easily varied via temperature and viscosity of the solvent. The method is applied to test the performance of a newly developed real time transient absorption setup with 300 ps time resolution and high sensitivity.

  14. Use of ruthenium dyes for subnanosecond detector fidelity testing in real time transient absorption

    SciTech Connect

    Byrdin, Martin; Thiagarajan, Viruthachalam; Villette, Sandrine; Espagne, Agathe; Brettel, Klaus

    2009-04-15

    Transient absorption spectroscopy is a powerful tool for the study of photoreactions on time scales from femtoseconds to seconds. Typically, reactions slower than {approx}1 ns are recorded by the ''classical'' technique; the reaction is triggered by an excitation flash, and absorption changes accompanying the reaction are recorded in real time using a continuous monitoring light beam and a detection system with sufficiently fast response. The pico- and femtosecond region can be accessed by the more recent ''pump-probe'' technique, which circumvents the difficulties of real time detection on a subnanosecond time scale. This is paid for by accumulation of an excessively large number of shots to sample the reaction kinetics. Hence, it is of interest to extend the classical real time technique as far as possible to the subnanosecond range. In order to identify and minimize detection artifacts common on a subnanosecond scale, like overshoot, ringing, and signal reflections, rigorous testing is required of how the detection system responds to fast changes of the monitoring light intensity. Here, we introduce a novel method to create standard signals for detector fidelity testing on a time scale from a few picoseconds to tens of nanoseconds. The signals result from polarized measurements of absorption changes upon excitation of ruthenium complexes {l_brace}[Ru(bpy){sub 3}]{sup 2+} and a less symmetric derivative{r_brace} by a short laser flash. Two types of signals can be created depending on the polarization of the monitoring light with respect to that of the excitation flash: a fast steplike bleaching at magic angle and a monoexponentially decaying bleaching for parallel polarizations. The lifetime of the decay can be easily varied via temperature and viscosity of the solvent. The method is applied to test the performance of a newly developed real time transient absorption setup with 300 ps time resolution and high sensitivity.

  15. Performance of timing RPC detectors for relativistic ions and design of a time-of-flight detector (iToF) for the R3B-FAIR experiment for fission and spallation reactions

    SciTech Connect

    Casarejos, E.; Ayyad, Y.; Benlliure, J.; Duran, I.; Paradela, C.; Lopez-Lago, M.; Segade, A.; Vilan, J. A.

    2011-07-01

    Resistive-plate-chambers (RPCs) were proposed to be used to build a time-of-flight detector for relativist heavy ions of the R3B-FAIR experiment, as well as other applications. State-of-the-art reaction codes allow for evaluating the requirements of the detector. The specific needs that working with heavy ions impose about material thicknesses are solved with new design concepts. We built prototypes and investigated the behaviour of RPCs tested with relativistic heavy ions. We measured the efficiency and streamer presence for ions with atomic numbers up to 38. Electron beams were used to study the timing capabilities of the prototypes. (authors)

  16. Monte Carlo Simulation Study on the Time Resolution of a PMT-Quadrant-Sharing LSO Detector Block for Time-of-Flight PET.

    PubMed

    Liu, Shitao; Li, Hongdi; Zhang, Yuxuan; Ramirez, Rocio A; Baghaei, Hossain; An, Shaohui; Wang, Chao; Liu, Jiguo; Wong, Wai-Hoi

    2009-01-01

    We developed a detailed Monte Carlo simulation method to study the time resolution of detectors for time-of-flight positron emission tomography (TOF PET). The process of gamma ray interaction in detectors, scintillation light emission and transport inside the detectors, the photoelectron generation and anode signal generation in the photomultiplier tube (PMT), and the electronics process of discriminator are simulated. We tested this simulation method using published experimental data, and found that it can generate reliable results. Using this method, we simulated the time resolution for a 13 × 13 detector block of 4 × 4 × 20 mm(3) lutetium orthosilicate (LSO) crystals coupled to four 2-inch PMTs using PMT-quadrant-sharing (PQS) technology. We analyzed the effects of several factors, including the number of photoelectrons, light transport, transit time spread (TTS), and the depth of interaction (DOI). The simulation results indicated that system time resolution of 360 ps should be possible with currently available fast PMTs. This simulation method can also be used to simulate the time resolution of other detector design method.

  17. Exploratory study of a novel low occupancy vertex detector architecture based on high precision timing for high luminosity particle colliders

    NASA Astrophysics Data System (ADS)

    Orel, Peter; Varner, Gary S.; Niknejadi, Pardis

    2017-06-01

    Vertex detectors provide space-time coordinates for the traversing charged particle decay products closest to the interaction point. Resolving these increasingly intense particle fluences at high luminosity particle colliders, such as SuperKEKB, is an ever growing challenge. This results in a non-negligible occupancy of the vertex detector using existing low material budget techniques. Consequently, new approaches are being studied that meet the vertexing requirements while lowering the occupancy. In this paper, we introduce a novel vertex detector architecture. Its design relies on an asynchronous digital pixel matrix in combination with a readout based on high precision time-of-flight measurement. Denoted the Timing Vertex Detector (TVD), it consists of a binary pixel array, a transmission line for signal collection, and a readout ASIC. The TVD aims to have a spatial resolution comparable to the existing Belle2 vertex detector. At the same time it offers a reduced occupancy by a factor of ten while decreasing the channel count by almost three orders of magnitude. Consequently, reducing the event size from about 1 MB/event to about 5.9 kB/event.

  18. Research on the recently dead: an historical and ethical examination.

    PubMed

    Tomasini, F

    2008-01-01

    INTRODUCTION AND SOURCES OF DATA: This paper briefly outlines the history of research on the recently dead, before critically exploring 1. In what sense can we harm the dead? 2. What are the justificatory arguments for employing family or parental consent for medical research on dead relatives? AREAS OF AGREEMENT, CONTROVERSY, GROWING POINTS OF INTEREST AND AREAS TIMELY FOR DEVELOPING RESEARCH: The controversy surrounding harm in relation to research on dead bodies largely depends on how dead people are perceived. That is, 1. As Cadavers. 2. As Ante-mortem persons. 3. By Significant others. Controversy over whether we need to have consent from significant others (bereaved relatives) depends on the weight we give to the bereaved and their experience of the dead. Understanding this is timely in developing research and is relevant to the issue of consent around organ donation for transplants.

  19. Communicating with the Dead

    NASA Astrophysics Data System (ADS)

    Kurtz, Paul

    2000-03-01

    Communicating with dead persons is popular in the new paranatural (paranormal-spiritual) paradigm that has emerged today. This view violates physicalist principles. Scientists have investigated survival questions for over 150 years. Beginning with the Fox sisters in 1848, they have examined reports of apparitions and ghosts, rappings, table turnings, teleportation, levitation, and other alleged physicalist manifestations in séances. Such reports were discredited by uncovering hoaxes by alleged mediums, e.g. Eusapia Palladino (1910s), Marjorie Crandon (1920s), etc. In recent decades there has been a revival of interest in survival with reports of near-death experiences. Skeptics ask: Are such persons clinically dead? Today, channelers such as James Van Praagh, John Edwards, and Sylvia Browne claim to communicate directly with the dead (the "Sixth Sense"). There is no attempt at physical confirmation or independent eyewitness corroboration so essential for scientific inquiry. Subjective claims are uncritically accepted at their face value, though alternative naturalistic explanations can be given for the alleged phenomena.

  20. Dead Sea rhodopsins revisited.

    PubMed

    Bodaker, Idan; Suzuki, Marcelino T; Oren, Aharon; Béjà, Oded

    2012-12-01

    The Dead Sea is a unique hypersaline ecosystem with near toxic magnesium levels (∼2 M), dominance of divalent cations and a slightly acidic pH. Previously, we reported a haloarchaeon related to Halobacterium salinarum to dominate in a microbial bloom that developed in 1992 in the upper water layers of the lake following massive freshwater runoff. Whether this clade also dominated an earlier bloom in 1980-1982 cannot be ascertained as no samples for cultivation-independent analysis were preserved. The presence of the light-driven proton pump bacteriorhodopsin was reported in the 1980-1982 bloom of prokaryotes that had developed in the Dead Sea. To test the hypothesis that bacteriorhodopsin proton pumping may play a major role in determining what type of haloarchaea may dominate in specific bloom conditions, we compared rhodopsin genes recovered from Dead Sea biomass collected in different periods with genes coding for retinal proteins in isolated haloarchaea. Novel bacteriorhodopsin and sensory rhodopsin genes were found in samples collected in 2007 and 2010. The fact that no rhodopsin genes were recovered from samples collected during the 1992 bloom, which was dominated by a single species, suggests that different clades were present in the 1980-1982 and 1992 blooms, and that bacteriorhodopsin proton pumping did not necessarily play a determinative role in the dominance of specific halophiles in the blooms.

  1. The effect of dead-timeless silicon strip readout at CDF II

    NASA Astrophysics Data System (ADS)

    Affolder, A.; Garcia-Sciveres, M.; Goldstein, J.; Hill, C.; Stuart, D.; Volobouev, I.

    2003-03-01

    The Run IIa CDF Silicon Upgrade has recently finished installation. The detector uses revision D of the SVX3 readout IC. This final revision incorporated new features in order to improve the potential of dead-timeless operation. This paper describes measurements of dead-timeless effects on silicon strip readout on the test bench. This paper also describes tests of the dynamic pedestal subtraction circuitry, which is shown to improve greatly the dead-timeless performance of the silicon systems.

  2. The Effect of dead-timeless silicon strip readout at CDF II

    SciTech Connect

    A. Affolder et al.

    2002-03-12

    The Run IIa CDF Silicon Upgrade has recently finished installation. The detector uses revision D of the SVX3 readout IC. This final revision incorporated new features in order to improve the potential of dead-timeless operation. This paper describes measurements of dead-timeless effects on silicon strip readout on the test bench. This paper also describes tests of the dynamic pedestal subtraction circuitry, which is shown to improve greatly the dead-timeless performance of the silicon systems.

  3. Performance of the Time Expansion Chamber / Transition Radiation Detector in PHENIX Experiment at RHIC

    NASA Astrophysics Data System (ADS)

    Luiz Silva, Cesar

    2004-10-01

    The Time Expansion Chamber / Transition Radiation Detector (TEC/TRD) in the PHENIX Experiment at RHIC measures ionization losses (dE/dX) and transition radiation from charged particles produced by beam collisions. It is designed to perform tracking and identification for charged particles on very high particle multiplicity environment. The TEC/TRD consists of 24 wire chambers readout on both sides filled with recycled Xe-based gas mixture. This wire chamber configuration, besides providing measurements of ionization losses for charged particles, can absorb X-Ray photons generated by transition radiation from incident particles with γ>1000 crossing fiber radiators placed at the entrance of the chambers. This allows TEC/TRD to distinguish electrons from the huge pion signal produced over a broad momentum range (1GeV/ctimes every collision providing the drift time as an additional variable to determine points for the charged particle's track. In this presentation we will show results on e/π separation for momentum above 1 GeV/c and momentum resolution using TEC/TRD in Au-Au collisions at √s=200 GeV/c and √s=62.4 GeV/c.

  4. Travel Time Estimation Using Freeway Point Detector Data Based on Evolving Fuzzy Neural Inference System.

    PubMed

    Tang, Jinjun; Zou, Yajie; Ash, John; Zhang, Shen; Liu, Fang; Wang, Yinhai

    2016-01-01

    Travel time is an important measurement used to evaluate the extent of congestion within road networks. This paper presents a new method to estimate the travel time based on an evolving fuzzy neural inference system. The input variables in the system are traffic flow data (volume, occupancy, and speed) collected from loop detectors located at points both upstream and downstream of a given link, and the output variable is the link travel time. A first order Takagi-Sugeno fuzzy rule set is used to complete the inference. For training the evolving fuzzy neural network (EFNN), two learning processes are proposed: (1) a K-means method is employed to partition input samples into different clusters, and a Gaussian fuzzy membership function is designed for each cluster to measure the membership degree of samples to the cluster centers. As the number of input samples increases, the cluster centers are modified and membership functions are also updated; (2) a weighted recursive least squares estimator is used to optimize the parameters of the linear functions in the Takagi-Sugeno type fuzzy rules. Testing datasets consisting of actual and simulated data are used to test the proposed method. Three common criteria including mean absolute error (MAE), root mean square error (RMSE), and mean absolute relative error (MARE) are utilized to evaluate the estimation performance. Estimation results demonstrate the accuracy and effectiveness of the EFNN method through comparison with existing methods including: multiple linear regression (MLR), instantaneous model (IM), linear model (LM), neural network (NN), and cumulative plots (CP).

  5. Accurate modeling of SiPM detectors coupled to FE electronics for timing performance analysis

    NASA Astrophysics Data System (ADS)

    Ciciriello, F.; Corsi, F.; Licciulli, F.; Marzocca, C.; Matarrese, G.; Del Guerra, A.; Bisogni, M. G.

    2013-08-01

    It has already been shown how the shape of the current pulse produced by a SiPM in response to an incident photon is sensibly affected by the characteristics of the front-end electronics (FEE) used to read out the detector. When the application requires to approach the best theoretical time performance of the detection system, the influence of all the parasitics associated to the coupling SiPM-FEE can play a relevant role and must be adequately modeled. In particular, it has been reported that the shape of the current pulse is affected by the parasitic inductance of the wiring connection between SiPM and FEE. In this contribution, we extend the validity of a previously presented SiPM model to account for the wiring inductance. Various combinations of the main performance parameters of the FEE (input resistance and bandwidth) have been simulated in order to evaluate their influence on the time accuracy of the detection system, when the time pick-off of each single event is extracted by means of a leading edge discriminator (LED) technique.

  6. Electron Recoil rejection by decay time measurement in large liquid Xenon detectors

    NASA Astrophysics Data System (ADS)

    Namwongsa, P.; Banjongkan, A.; Chen, X.; Giboni, K. L.; Ji, X.; Kobdaj, C.; Kusano, H.; Yupeng, Y.

    2017-04-01

    Very large Liquid Xenon (LXe) Time Projection Chambers (TPC) are employed to search for Dark Matter (DM). The DM particles are supposed to interact with the whole nucleus, compared to background of γ-rays, which interact with the electrons. Therefore, DM signals are caused by Nuclear Recoil (NR) instead of the Electron Recoils (ER). In ER and NR events differ in pulse shape since the ratios of light from direct scintillation and recombination are different. To discriminate against residual ER events would be possible if one can distinguish the differences in decay times. This method can be successfully applied in Liquid Argon TPCs. In LXe, however, it is generally assumed that these differences are too small to be distinguished at low energies. The easiest algorithm of Pulse Shape Discrimination (PSD) distinguishes the event type based on the number of photons emitted much later than the longest decay time. At low energies too much of the timing information is lost, and this method does not perform well. However, the timing of all photons does contain sufficient information. If we use sufficiently fast PMTs, have a large enough bandwidth in the Front End electronics, and avoid reflections then we should reach a background rejection better than 10-2 even at 2 keVee. In our Decay Time Measurement (DTM) method the decay curves are compared with a model on an event by event basis. Statistically this is independent from the charge over light (`S2/S1') cut normally applied in Dual Phase detectors. Applying both rejection mechanisms a LXeTPC can become `quasi background free'.

  7. Development of a real-time digital radiography system using a scintillator-type flat-panel detector

    NASA Astrophysics Data System (ADS)

    Ikeda, Shigeyuki; Suzuki, Katsumi; Ishikawa, Ken; Okajima, Kenichi

    2001-06-01

    In order to study the advantage and remaining problems of FPD (flat panel detector) for clinical use by the real-time DR (digital radiography) system, we developed a prototype system using a scintillator type FPD and which was compared with previous I.I.-CCD type real-time DR. We replaced the X- ray detector of DR-2000X from I.I.-4M (4 million pixels)-CCD camera to the scintillator type dynamic FPD(7' X 9', 127 micrometers ), which can take both radiographic and fluoroscopic images. We obtained the images of head and stomach phantoms, and discussed about the image quality with medical doctors.

  8. Towards Software-Based Real-Time Singles and Coincidence Processing of Digital PET Detector Raw Data

    NASA Astrophysics Data System (ADS)

    Goldschmidt, Benjamin; Lerche, Christoph W.; Solf, Torsten; Salomon, André; Kiessling, Fabian; Schulz, Volkmar

    2013-06-01

    This paper presents a software-based singles and coincidence processing (SCP) architecture for a digital PET/MR system that is based on SiPM detectors with local digitization coupled to preclinical crystal arrays. Compared with traditional PET systems, our system outputs detector raw data of the individual detector elements via optical Gigabit Ethernet interfaces instead of singles or coincidences. The raw data contains the digitized timestamps, energies, and identifiers of triggered SiPM pixels (hits). Although this approach requires a high bandwidth for the detector data transmission system, the availability of detector raw data offers unique opportunities to employ more accurate and computationally complex, iterative algorithms, which can lead to PET images with higher quality and accuracy. In this paper, we evaluate a parallel software-based SCP for three different crystal position estimation approaches with regard to its real-time capabilities. The SCP receives detector raw data as input and outputs list-mode coincidence data. The investigated PET system features ten singles processing units (SPU), each equipped with two PET detector stacks and a Gigabit Ethernet interface to a data acquisition and processing server (Dell Poweredge R910 equipped with 4× Intel Xeon X7560@2.27 GHz CPUs and 256 GByte DDR3-RAM), allowing lossless real-time acquisition of the entire raw data stream. Using the detector raw data of three previously stored measurements, our results show that the throughput (in Mhits/s) of a center-of-gravity (COG)-based parallel SCP is nearly 4× higher on average than the estimated detector raw data output that is generated from an activity of 37 MBq in the iso-center of the detector ring. Under the same conditions, an iterative maximum-likelihood (ML)-based parallel SCP leads to a 6× higher throughput on average, while a Gaussian-based parallel SCP also results in a 13× higher throughput on average. Compared with a serial processing approach, the

  9. Gigahertz-gated InGaAs/InP single-photon detector with detection efficiency exceeding 55% at 1550 nm

    SciTech Connect

    Comandar, L. C.; Fröhlich, B.; Dynes, J. F.; Sharpe, A. W.; Lucamarini, M.; Yuan, Z. L.; Shields, A. J.; Penty, R. V.

    2015-02-28

    We report on a gated single-photon detector based on InGaAs/InP avalanche photodiodes (APDs) with a single-photon detection efficiency exceeding 55% at 1550 nm. Our detector is gated at 1 GHz and employs the self-differencing technique for gate transient suppression. It can operate nearly dead time free, except for the one clock cycle dead time intrinsic to self-differencing, and we demonstrate a count rate of 500 Mcps. We present a careful analysis of the optimal driving conditions of the APD measured with a dead time free detector characterization setup. It is found that a shortened gate width of 360 ps together with an increased driving signal amplitude and operation at higher temperatures leads to improved performance of the detector. We achieve an afterpulse probability of 7% at 50% detection efficiency with dead time free measurement and a record efficiency for InGaAs/InP APDs of 55% at an afterpulse probability of only 10.2% with a moderate dead time of 10 ns.

  10. Time-Resolved Imaging of the MALDI Linear-TOF Ion Cloud: Direct Visualization and Exploitation of Ion Optical Phenomena Using a Position- and Time-Sensitive Detector

    NASA Astrophysics Data System (ADS)

    Ellis, Shane R.; Soltwisch, Jens; Heeren, Ron M. A.

    2014-05-01

    In this study, we describe the implementation of a position- and time-sensitive detection system (Timepix detector) to directly visualize the spatial distributions of the matrix-assisted laser desorption ionization ion cloud in a linear-time-of-flight (MALDI linear-ToF) as it is projected onto the detector surface. These time-resolved images allow direct visualization of m/z-dependent ion focusing effects that occur within the ion source of the instrument. The influence of key parameters, namely extraction voltage ( E V ), pulsed-ion extraction (PIE) delay, and even the matrix-dependent initial ion velocity was investigated and were found to alter the focusing properties of the ion-optical system. Under certain conditions where the spatial focal plane coincides with the detector plane, so-called x-y space focusing could be observed (i.e., the focusing of the ion cloud to a small, well-defined spot on the detector). Such conditions allow for the stigmatic ion imaging of intact proteins for the first time on a commercial linear ToF-MS system. In combination with the ion-optical magnification of the system (~100×), a spatial resolving power of 11-16 μm with a pixel size of 550 nm was recorded within a laser spot diameter of ~125 μm. This study demonstrates both the diagnostic and analytical advantages offered by the Timepix detector in ToF-MS.

  11. High-dose neutron detector project update

    SciTech Connect

    Menlove, Howard Olsen; Henzlova, Daniela

    2016-08-10

    These are the slides for a progress review meeting by the sponsor. This is an update on the high-dose neutron detector project. In summary, improvements in both boron coating and signal amplification have been achieved; improved boron coating materials and procedures have increased efficiency by ~ 30-40% without the corresponding increase in the detector plate area; low dead-time via thin cell design (~ 4 mm gas gaps) and fast amplifiers; prototype PDT 8” pod has been received and testing is in progress; significant improvements in efficiency and stability have been verified; use commercial PDT 10B design and fabrication to obtain a faster path from the research to practical high-dose neutron detector.

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

    SciTech Connect

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

    2001-07-01

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

  13. Fast neutron tomography with real-time pulse-shape discrimination in organic scintillation detectors

    NASA Astrophysics Data System (ADS)

    Joyce, Malcolm J.; Agar, Stewart; Aspinall, Michael D.; Beaumont, Jonathan S.; Colley, Edmund; Colling, Miriam; Dykes, Joseph; Kardasopoulos, Phoevos; Mitton, Katie

    2016-10-01

    A fast neutron tomography system based on the use of real-time pulse-shape discrimination in 7 organic liquid scintillation detectors is described. The system has been tested with a californium-252 source of dose rate 163 μSv/h at 1 m and neutron emission rate of 1.5×107 per second into 4π and a maximum acquisition time of 2 h, to characterize two 100×100×100 mm3 concrete samples. The first of these was a solid sample and the second has a vertical, cylindrical void. The experimental data, supported by simulations with both Monte Carlo methods and MATLAB®, indicate that the presence of the internal cylindrical void, corners and inhomogeneities in the samples can be discerned. The potential for fast neutron assay of this type with the capability to probe hydrogenous features in large low-Z samples is discussed. Neutron tomography of bulk porous samples is achieved that combines effective penetration not possible with thermal neutrons in the absence of beam hardening.

  14. High-performance SPAD array detectors for parallel photon timing applications

    NASA Astrophysics Data System (ADS)

    Rech, I.; Cuccato, A.; Antonioli, S.; Cammi, C.; Gulinatti, A.; Ghioni, M.

    2012-02-01

    Over the past few years there has been a growing interest in monolithic arrays of single photon avalanche diodes (SPAD) for spatially resolved detection of faint ultrafast optical signals. SPADs implemented in planar technologies offer the typical advantages of microelectronic devices (small size, ruggedness, low voltage, low power, etc.). Furthermore, they have inherently higher photon detection efficiency than PMTs and are able to provide, beside sensitivities down to single-photons, very high acquisition speeds. In order to make SPAD array more and more competitive in time-resolved application it is necessary to face problems like electrical crosstalk between adjacent pixel, moreover all the singlephoton timing electronics with picosecond resolution has to be developed. In this paper we present a new instrument suitable for single-photon imaging applications and made up of 32 timeresolved parallel channels. The 32x1 pixel array that includes SPAD detectors represents the system core, and an embedded data elaboration unit performs on-board data processing for single-photon counting applications. Photontiming information is exported through a custom parallel cable that can be connected to an external multichannel TCSPC system.

  15. Simultaneous real-time visible and infrared video with single-pixel detectors

    NASA Astrophysics Data System (ADS)

    Edgar, Matthew. P.; Gibson, Graham M.; Bowman, Richard W.; Sun, Baoqing; Radwell, Neal; Mitchell, Kevin J.; Welsh, Stephen S.; Padgett, Miles J.

    2015-05-01

    Conventional cameras rely upon a pixelated sensor to provide spatial resolution. An alternative approach replaces the sensor with a pixelated transmission mask encoded with a series of binary patterns. Combining knowledge of the series of patterns and the associated filtered intensities, measured by single-pixel detectors, allows an image to be deduced through data inversion. In this work we extend the concept of a ‘single-pixel camera’ to provide continuous real-time video at 10 Hz , simultaneously in the visible and short-wave infrared, using an efficient computer algorithm. We demonstrate our camera for imaging through smoke, through a tinted screen, whilst performing compressive sampling and recovering high-resolution detail by arbitrarily controlling the pixel-binning of the masks. We anticipate real-time single-pixel video cameras to have considerable importance where pixelated sensors are limited, allowing for low-cost, non-visible imaging systems in applications such as night-vision, gas sensing and medical diagnostics.

  16. Determining the detection thresholds for harbor porpoise clicks of autonomous data loggers, the Timing Porpoise Detectors.

    PubMed

    Verfuß, Ursula K; Dähne, Michael; Gallus, Anja; Jabbusch, Martin; Benke, Harald

    2013-09-01

    Timing Porpoise Detectors (T-PODs, Chelonia Ltd.) are autonomous passive acoustic devices for monitoring odontocetes. They register the time of occurrence and duration of high frequency pulsed sounds as possible odontocetes echolocation clicks. Because of evolution, five T-POD versions exist. Although the manufacturer replaced those by a digital successor, the C-POD, T-PODs are still used, and data from many field studies exist. Characterizing the acoustic properties of T-PODs enables the interpretation of data obtained with different devices. Here, the detection thresholds of different T-POD versions for harbor porpoise clicks were determined. While thresholds among devices were quite variable in the first T-POD generations, they became more standardized in newer versions. Furthermore, the influence of user-controlled settings on the threshold was investigated. From version 3 on, the detection threshold was found to be easily adjustable with version-dependent setting options "minimum intensity" and "sensitivity," enabling the presetting of standard thresholds. In version 4, the setting "click bandwidth" had a strong influence on the detection threshold, while "selectivity" in version 3 and "noise adaptation = ON" or "OFF" in version 4 hardly influenced thresholds obtained in the tank tests. Nevertheless, the latter setting may influence thresholds in a complex acoustic environment like the sea.

  17. Simultaneous real-time visible and infrared video with single-pixel detectors

    PubMed Central

    Edgar, Matthew. P.; Gibson, Graham M.; Bowman, Richard W.; Sun, Baoqing; Radwell, Neal; Mitchell, Kevin J.; Welsh, Stephen S.; Padgett, Miles J.

    2015-01-01

    Conventional cameras rely upon a pixelated sensor to provide spatial resolution. An alternative approach replaces the sensor with a pixelated transmission mask encoded with a series of binary patterns. Combining knowledge of the series of patterns and the associated filtered intensities, measured by single-pixel detectors, allows an image to be deduced through data inversion. In this work we extend the concept of a ‘single-pixel camera’ to provide continuous real-time video at 10 Hz , simultaneously in the visible and short-wave infrared, using an efficient computer algorithm. We demonstrate our camera for imaging through smoke, through a tinted screen, whilst performing compressive sampling and recovering high-resolution detail by arbitrarily controlling the pixel-binning of the masks. We anticipate real-time single-pixel video cameras to have considerable importance where pixelated sensors are limited, allowing for low-cost, non-visible imaging systems in applications such as night-vision, gas sensing and medical diagnostics. PMID:26001092

  18. Signal-Conditioning Block of a 1 × 200 CMOS Detector Array for a Terahertz Real-Time Imaging System

    PubMed Central

    Yang, Jong-Ryul; Lee, Woo-Jae; Han, Seong-Tae

    2016-01-01

    A signal conditioning block of a 1 × 200 Complementary Metal-Oxide-Semiconductor (CMOS) detector array is proposed to be employed with a real-time 0.2 THz imaging system for inspecting large areas. The plasmonic CMOS detector array whose pixel size including an integrated antenna is comparable to the wavelength of the THz wave for the imaging system, inevitably carries wide pixel-to-pixel variation. To make the variant outputs from the array uniform, the proposed signal conditioning block calibrates the responsivity of each pixel by controlling the gate bias of each detector and the voltage gain of the lock-in amplifiers in the block. The gate bias of each detector is modulated to 1 MHz to improve the signal-to-noise ratio of the imaging system via the electrical modulation by the conditioning block. In addition, direct current (DC) offsets of the detectors in the array are cancelled by initializing the output voltage level from the block. Real-time imaging using the proposed signal conditioning block is demonstrated by obtaining images at the rate of 19.2 frame-per-sec of an object moving on the conveyor belt with a scan width of 20 cm and a scan speed of 25 cm/s. PMID:26950128

  19. Signal-Conditioning Block of a 1 × 200 CMOS Detector Array for a Terahertz Real-Time Imaging System.

    PubMed

    Yang, Jong-Ryul; Lee, Woo-Jae; Han, Seong-Tae

    2016-03-02

    A signal conditioning block of a 1 × 200 Complementary Metal-Oxide-Semiconductor (CMOS) detector array is proposed to be employed with a real-time 0.2 THz imaging system for inspecting large areas. The plasmonic CMOS detector array whose pixel size including an integrated antenna is comparable to the wavelength of the THz wave for the imaging system, inevitably carries wide pixel-to-pixel variation. To make the variant outputs from the array uniform, the proposed signal conditioning block calibrates the responsivity of each pixel by controlling the gate bias of each detector and the voltage gain of the lock-in amplifiers in the block. The gate bias of each detector is modulated to 1 MHz to improve the signal-to-noise ratio of the imaging system via the electrical modulation by the conditioning block. In addition, direct current (DC) offsets of the detectors in the array are cancelled by initializing the output voltage level from the block. Real-time imaging using the proposed signal conditioning block is demonstrated by obtaining images at the rate of 19.2 frame-per-sec of an object moving on the conveyor belt with a scan width of 20 cm and a scan speed of 25 cm/s.

  20. Real-time Transient Monitoring With the HAWC Detector: Design and Performance

    NASA Astrophysics Data System (ADS)

    Wisher, Ian Gabriel

    Blazars are some of the most energetic environments in the Universe with exceptionally strong non-thermal emission. Since the detection of VHE variability in the blazar Markarian 421, observations of blazars and their VHE variability have been an active field of research. Through long campaigns of observations, blazars have shown variability over timescales that vary from minutes to days across the electromagnetic spectrum from radio to TeV gamma rays. Though rare, the variability can also have extreme outburst events where the flux peaks at several orders of magnitude higher than the quiescent state of the source. These outbursts are interesting not only for constraining the models of acceleration and variability but also as tools to study other physics topics such as the extragalactic background light, intergalactic magnetic field, and Lorentz invariance. Though powerful, the rarity of these events makes studies challenging and motivates additional searches and detections. The High Altitude Water Cherenkov (HAWC) detector is an extensive air shower instrument with a high duty cycle, large field of view, and extraordinary sensitivity to TeV gamma rays. This allows HAWC to perform unbiased monitoring of a large number of different sources for flaring states and catch rare events such as the aforementioned blazar flares. This work presents a search for short timescale flares from known blazars and TeV sources for the first year of HAWC data with the capability to generate alerts in real time. In the course of this work, a variety of new hardware, software, and detection techniques were developed in conjunction with the construction of the HAWC detector. These include hardware development on the design of the main data acquisition system, electronics integrations and testing, design/testing of the online reconstruction system, and design of the electronics for the outrigger extension. Algorithms and methods to detect transients in HAWC time series data were developed

  1. Time-resolved diffuse reflectance measurement carried out on the head of an adult at large source-detector separation.

    PubMed

    Liebert, Adam; Sawosz, Piotr; Kacprzak, Michal; Weigl, Wojciech; Botwicz, Marcin; Maniewski, Roman

    2010-01-01

    Multichannel time-resolved optical monitoring system was constructed for measurements of diffuse reflectance in optically turbid medium at very large source-detector separation up to 9 cm. The system is based on femtosecond TiSa laser and sensitive photomultiplier tube detector. The laser light of 300mW of power was delivered to the surface of the head with the use of an optical fiber. A beam expander was applied in order to distribute the laser light on a large spot which allowed to avoid energetic stimulation of the tissue. The photomultiplier tube detector was positioned directly on the surface of the medium at the distance of 9cm from the center of the source position. In this paper we report results of an in-vivo experiment carried out on the head of an adult healthy volunteer. The time-resolved system was applied during intravenous injection of an optical contrast agent (indocyanine green - ICG) and the distributions of times of flight of photons were successfully acquired showing inflow and washout of the dye to the tissue. Time-courses of the moments of distributions of times of flight of photons are presented and compared with the results obtained simultaneously at shorter source-detector separations (3 cm, 4 cm and 5 cm).

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

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

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

  3. Dead Band Controls Guide.

    DTIC Science & Technology

    1978-11-01

    n o m i z e r c on t ro l , damper repair may re quire c onsideration. 2. No tubin g costs are included in the above estima tes . Typically 150 to...guidelines include techniques for estimating construction and maintenance cost , and performing economic analysis for each system . N \\ 0~c...43 Cost Estimate 43 Payback Anal ysis 43 PART I V A P P E N D I C E S A EXAMPLE - COST ESTIMATE OF DEAD BAND RETROFIT 52 B E X A M P L E - P A Y B A

  4. Can the dead be brought into disrepute?

    PubMed

    Masterton, Malin; Hansson, Mats G; Höglund, Anna T; Helgesson, Gert

    2007-01-01

    Queen Christina of Sweden was unconventional in her time, leading to hypotheses on her gender and possible hermaphroditic nature. If genetic analysis can substantiate the latter claim, could this bring the queen into disrepute 300 years after her death? Joan C. Callahan has argued that if a reputation changes, this constitutes a change only in the group of people changing their views and not in the person whose reputation it is. Is this so? This paper analyses what constitutes change and draws out the implications to the reputation of the dead. It is argued that a reputation is a relational property which can go through changes. The change is "real" for the group changing their views on Queen Christina and of a Cambridge kind for the long dead queen herself. Cambridge changes result in new properties being acquired, some of which can be of significance. Although the dead cannot go through any non-relational changes, it is possible for the dead to change properties through Cambridge changes. In this sense changes in reputation do affect the dead, and thus Queen Christina can acquire a new property, in this case possibly a worse reputation.

  5. Antipodal neutron time of flight (nToF) detectors more than double their diagnostic value

    NASA Astrophysics Data System (ADS)

    Kilkenny, Joseph; Knauer, James; Caggiano, Joseph; Eckart, Mark; Hatarik, Robert; Munro, David; Sayre, Daniel; Spears, Brian

    2014-10-01

    Moments of the neutron-velocity distribution give unique insights to the quality of an inertial confinement fusion (ICF) implosion. The three, 20 m distance nToF detectors on the NIF are being augmented by adding an antipodal detector to each of them. Antipodal pairs of detectors increase the sampling of imploded DT ice but also allow an accurate measurement of the areal density of the odd modes of the compressed ice from the un-scattered yield ratio, and with the two measurements distinguishing center of mass drift velocity from the thermodynamic ion temperature. NNSA Contract Number DE-AC52-07NA27344.

  6. Experience using an automated fault location system with a time-of-flight wall detector array

    NASA Astrophysics Data System (ADS)

    Olson, D.; Greiman, W.; Hall, D.; Balaban, D.; Day, C.

    1990-08-01

    We describe the architecture of a general purpose monitoring system and give examples of its use with a 300 element detector array in a relativistic heavy ion experiment. The system has a simple and well defined interface between the detector specific parts of the system and those which are independent of any detector specific features. Tracking simple statistics on the fundamental data items (ADC and TDC values) are sufficient to diagnose the higher level components in the system. The monitoring of on-line beam data provides a sensitive monitor of global parameters of the experiment.

  7. A VXIbus based trigger for the CLAS detector at CEBAF

    SciTech Connect

    Doughty, D.C. Jr.; Englert, J.; Hale, R.; Lemon, S. ); Leung, P. ); Cuevas, C.; Joyce, D. )

    1992-04-01

    This paper discusses a VXIbus based first level triggering system for the CLAS detector at CEBAF which has been designed and prototyped. It uses pipelining and a triple memory lookup to produce a dead-timeless trigger decision with an average latency of 110 ns and a jitter of 20 ns. The VXIbus Extended Start/Stop triggering protocols allow sub-nanosecond time synchronization.

  8. A VXIbus based trigger for the CLAS detector at CEBAF

    SciTech Connect

    D.C. Doughty, Jr.; J. Englert; R. Hale; S. Lemon; P. Leung; C. Cuevas; D. Joyce

    1992-04-01

    A VXIbus based first level triggering system for the CLAS detector at CEBAF has been designed and prototyped. It uses pipelining and a triple memory lookup to produce a dead-timeless trigger decision with an average latency of 110 nS and a jitter of 20 nS. The VXIbus Extended Start/Stop triggering protocols allow sub-nanosecond time synchronization.

  9. 78 FR 24462 - Culturally Significant Objects Imported for Exhibition; Determinations: “The Dead Sea Scrolls...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-25

    ... Culturally Significant Objects Imported for Exhibition; Determinations: ``The Dead Sea Scrolls: Life and Faith in Ancient Times'' Formerly Titled ``The Dead Sea Scrolls: Life and Faith in Biblical Times... the exhibition ``The Dead Sea Scrolls: Life and Faith in Biblical Times.'' The referenced notice...

  10. 78 FR 16565 - Culturally Significant Objects Imported for Exhibition Determinations: “The Dead Sea Scrolls...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-15

    ... Culturally Significant Objects Imported for Exhibition Determinations: ``The Dead Sea Scrolls: Life and Faith in Ancient Times'' Formerly Titled ``The Dead Sea Scrolls: Life and Faith in Biblical Times'' ACTION... exhibition ``The Dead Sea Scrolls: Life and Faith in Biblical Times.'' The referenced notice was corrected on...

  11. 78 FR 62354 - Culturally Significant Objects Imported for Exhibition Determinations: “The Dead Sea Scrolls...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-18

    ... Culturally Significant Objects Imported for Exhibition Determinations: ``The Dead Sea Scrolls: Life and Faith in Ancient Times'' Formerly Titled ``The Dead Sea Scrolls: Life and Faith in Biblical Times'' ACTION... exhibition ``The Dead Sea Scrolls: Life and Faith in Biblical Times.'' The referenced notice was corrected on...

  12. 77 FR 64373 - Culturally Significant Objects Imported for Exhibition Determinations: “The Dead Sea Scrolls...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-19

    ... Culturally Significant Objects Imported for Exhibition Determinations: ``The Dead Sea Scrolls: Life and Faith in Ancient Times,'' Formerly Titled ``The Dead Sea Scrolls: Life and Faith in Biblical Times... the exhibition ``The Dead Sea Scrolls: Life and Faith in Biblical Times.'' The referenced notice is...

  13. Low-Timing-Jitter Near-Infrared Single-Photon-Sensitive 16-Channel Intensified-Photodiode Detector

    NASA Technical Reports Server (NTRS)

    Krainak, Michael A.; Lu, Wei; Yang, Guangning; Sun, Xiaoli; Sykora, Derek; Jurkovic, Mike; Aebi, Verle; Costello, Ken; Burns, Richard

    2011-01-01

    We developed a 16-channel InGaAsP photocathode intensified-photodiode (IPD) detector with 78 ps (1-sigma) timing-jitter, less than 500 ps FWHM impulse response, greater than 15% quantum efficiency at 1064 nm wavelength with 131 kcps dark counts at 15 C.

  14. Travel Time Estimation Using Freeway Point Detector Data Based on Evolving Fuzzy Neural Inference System

    PubMed Central

    Tang, Jinjun; Zou, Yajie; Ash, John; Zhang, Shen; Liu, Fang; Wang, Yinhai

    2016-01-01

    Travel time is an important measurement used to evaluate the extent of congestion within road networks. This paper presents a new method to estimate the travel time based on an evolving fuzzy neural inference system. The input variables in the system are traffic flow data (volume, occupancy, and speed) collected from loop detectors located at points both upstream and downstream of a given link, and the output variable is the link travel time. A first order Takagi-Sugeno fuzzy rule set is used to complete the inference. For training the evolving fuzzy neural network (EFNN), two learning processes are proposed: (1) a K-means method is employed to partition input samples into different clusters, and a Gaussian fuzzy membership function is designed for each cluster to measure the membership degree of samples to the cluster centers. As the number of input samples increases, the cluster centers are modified and membership functions are also updated; (2) a weighted recursive least squares estimator is used to optimize the parameters of the linear functions in the Takagi-Sugeno type fuzzy rules. Testing datasets consisting of actual and simulated data are used to test the proposed method. Three common criteria including mean absolute error (MAE), root mean square error (RMSE), and mean absolute relative error (MARE) are utilized to evaluate the estimation performance. Estimation results demonstrate the accuracy and effectiveness of the EFNN method through comparison with existing methods including: multiple linear regression (MLR), instantaneous model (IM), linear model (LM), neural network (NN), and cumulative plots (CP). PMID:26829639

  15. A real-time, nonintrusive trace gas detector based on laser photothermal deflection

    NASA Astrophysics Data System (ADS)

    de Vries, H. S. M.; Dam, N.; van Lieshout, M. R.; Sikkens, C.; Harren, F. J. M.; Reuss, J.

    1995-09-01

    We present the layout and technical details of a trace gas monitor based on photothermal deflection. The operating principle of this instrument, i.e., the deflection of a (weak) probe laser beam by the thermal refractive index gradient induced by trace gas absorption of an intense pump laser beam, allows nonintrusive measurements with good space and time resolution. An intra-cavity CO2 laser is used as the pump beam and a red HeNe laser as the probe. The latter runs perpendicular to the pump beam to optimize spatial resolution. To increase sensitivity, the probe laser is incorporated in a multipass setup. The instrument is demonstrated by the localization of ethylene emission sites on a cherry tomato and by monitoring ammonia production due to nitrogen fixation by cyanobacteria. Both C2H4 and NH3 can be detected at the 1-3 ppb level, at a spatial resolution of 2 mm (along the pump laser)×0.6 mm (perpendicular to it), and a response time of 0.1 s (without background correction) or 15 s (including background correction). Sensitivity can be increased at the expense of spatial resolution, and vice versa. In principle, this instrument is applicable to all those gases possessing a characteristic (``fingerprint'') spectrum in the CO2 laser range. The great advantage of the photothermal deflection technique with respect to other trace gas detection schemes lies in the nonintrusive character of the measurements. There is no need to enclose the sample in a vessel or to suck large volumes of air into the detector; measurements can be performed in open air and in real time. This should prove especially useful where sticky (polar) gases, like H2O, NH3, CH3OH, etc., are to be detected quantitatively. Main applications include air quality monitoring, especially concerning dry deposition rate measurements using the eddy correlation technique, and the study of volatile metabolite emission of biological samples.

  16. Characterization of neutron scatter for the 25-m neutron time of flight detector at the Z Accelerator

    NASA Astrophysics Data System (ADS)

    Norris, Edward; Hahn, Kelly; Chandler, Gordon; Ruiz, Carlos; Styron, Jedediah; Cooper, Gary; Jones, Brent; Torres, Jose; Spencer, Decker; Nelson, Alan

    2016-10-01

    We are investigating neutron scattering effects using Monte Carlo simulations for neutron time of flight (NTOF) detectors fielded at the Z Accelerator at Sandia National Laboratories. For the radial NTOF detector at 25 m, a large scatter distribution is observed during and after primary DD neutron signals produced during inertial-confinement fusion experiments which obfuscates inference of quantities such as ion temperature, yield, and liner areal density. We present comparisons of measurements with simulation results. We also propose improvements to this line-of-sight. Sandia is sponsored by the U.S. DOE's NNSA under contract DE-AC04-94AL85000.

  17. Real-Time Data Processing in the muon system of the D0 detector.

    SciTech Connect

    Neeti Parashar et al.

    2001-07-03

    This paper presents a real-time application of the 16-bit fixed point Digital Signal Processors (DSPs), in the Muon System of the D0 detector located at the Fermilab Tevatron, presently the world's highest-energy hadron collider. As part of the Upgrade for a run beginning in the year 2000, the system is required to process data at an input event rate of 10 KHz without incurring significant deadtime in readout. The ADSP21csp01 processor has high I/O bandwidth, single cycle instruction execution and fast task switching support to provide efficient multisignal processing. The processor's internal memory consists of 4K words of Program Memory and 4K words of Data Memory. In addition there is an external memory of 32K words for general event buffering and 16K words of Dual port Memory for input data queuing. This DSP fulfills the requirement of the Muon subdetector systems for data readout. All error handling, buffering, formatting and transferring of the data to the various trigger levels of the data acquisition system is done in software. The algorithms developed for the system complete these tasks in about 20 {micro}s per event.

  18. Enhancement of Real-Time THz Imaging System Based on 320 × 240 Uncooled Microbolometer Detector

    NASA Astrophysics Data System (ADS)

    Zheng, Xing; Wu, Zhiming; Gou, Jun; Liu, Ziji; Wang, Jun; Zheng, Jie; Luo, Zhenfei; Chen, Weiqing; Que, Longcheng; Jiang, Yadong

    2016-10-01

    A real-time terahertz (THz) imaging system was demonstrated based on a 320 × 240 uncooled microbolometer detector combined with a 2.52 THz far-infrared CO2 laser. On the top of micro-bridge structure (35 × 35 μm2), a 10 nm nickel-chromium (NiCr) thin film was deposited to enhance THz absorption, which was fabricated by a combined process of magnetron sputtering and reactive ion etching (RIE). By mechanical simulation using design of experiment (DOE) method, the minimum deformation was optimized to 0.0385 μm, and a measured deformation of 0.097 μm was achieved in the fabrication. The fabricated micro-bridge pixel was used for THz detection, and a responsivity of 1235 V/W was achieved with a noise equivalent power (NEP) of 87.4 pW/Hz1/2. THz imaging of metal gasket covered by label paper, paper clip in an envelope, and watermark of a banknote was demonstrated by a combination of histogram equalization (HE) and linear enhancement algorithm.

  19. Predicting crash likelihood and severity on freeways with real-time loop detector data.

    PubMed

    Xu, Chengcheng; Tarko, Andrew P; Wang, Wei; Liu, Pan

    2013-08-01

    Real-time crash risk prediction using traffic data collected from loop detector stations is useful in dynamic safety management systems aimed at improving traffic safety through application of proactive safety countermeasures. The major drawback of most of the existing studies is that they focus on the crash risk without consideration of crash severity. This paper presents an effort to develop a model that predicts the crash likelihood at different levels of severity with a particular focus on severe crashes. The crash data and traffic data used in this study were collected on the I-880 freeway in California, United States. This study considers three levels of crash severity: fatal/incapacitating injury crashes (KA), non-incapacitating/possible injury crashes (BC), and property-damage-only crashes (PDO). The sequential logit model was used to link the likelihood of crash occurrences at different severity levels to various traffic flow characteristics derived from detector data. The elasticity analysis was conducted to evaluate the effect of the traffic flow variables on the likelihood of crash and its severity.The results show that the traffic flow characteristics contributing to crash likelihood were quite different at different levels of severity. The PDO crashes were more likely to occur under congested traffic flow conditions with highly variable speed and frequent lane changes, while the KA and BC crashes were more likely to occur under less congested traffic flow conditions. High speed, coupled with a large speed difference between adjacent lanes under uncongested traffic conditions, was found to increase the likelihood of severe crashes (KA). This study applied the 20-fold cross-validation method to estimate the prediction performance of the developed models. The validation results show that the model's crash prediction performance at each severity level was satisfactory. The findings of this study can be used to predict the probabilities of crash at

  20. Comparison of Thermal Detector Arrays for Off-Axis THz Holography and Real-Time THz Imaging.

    PubMed

    Hack, Erwin; Valzania, Lorenzo; Gäumann, Gregory; Shalaby, Mostafa; Hauri, Christoph P; Zolliker, Peter

    2016-02-06

    In terahertz (THz) materials science, imaging by scanning prevails when low power THz sources are used. However, the application of array detectors operating with high power THz sources is increasingly reported. We compare the imaging properties of four different array detectors that are able to record THz radiation directly. Two micro-bolometer arrays are designed for infrared imaging in the 8-14 μm wavelength range, but are based on different absorber materials (i) vanadium oxide; (ii) amorphous silicon; (iii) a micro-bolometer array optimized for recording THz radiation based on silicon nitride; and (iv) a pyroelectric array detector for THz beam profile measurements. THz wavelengths of 96.5 μm, 118.8 μm, and 393.6 μm from a powerful far infrared laser were used to assess the technical performance in terms of signal to noise ratio, detector response and detectivity. The usefulness of the detectors for beam profiling and digital holography is assessed. Finally, the potential and limitation for real-time digital holography are discussed.

  1. A technique for verifying the input response function of neutron time-of-flight scintillation detectors using cosmic rays.

    PubMed

    Bonura, M A; Ruiz, C L; Fehl, D L; Cooper, G W; Chandler, G; Hahn, K D; Nelson, A J; Styron, J D; Torres, J A

    2014-11-01

    An accurate interpretation of DD or DT fusion neutron time-of-flight (nTOF) signals from current mode detectors employed at the Z-facility at Sandia National Laboratories requires that the instrument response functions (IRF's) be deconvolved from the measured nTOF signals. A calibration facility that produces detectable sub-ns radiation pulses is typically used to measure the IRF of such detectors. This work, however, reports on a simple method that utilizes cosmic radiation to measure the IRF of nTOF detectors, operated in pulse-counting mode. The characterizing metrics reported here are the throughput delay and full-width-at-half-maximum. This simple approach yields consistent IRF results with the same detectors calibrated in 2007 at a LINAC bremsstrahlung accelerator (Idaho State University). In particular, the IRF metrics from these two approaches and their dependence on the photomultipliers bias agree to within a few per cent. This information may thus be used to verify if the IRF for a given nTOF detector employed at Z has changed since its original current-mode calibration and warrants re-measurement.

  2. A technique for verifying the input response function of neutron time-of-flight scintillation detectors using cosmic raysa)

    NASA Astrophysics Data System (ADS)

    Bonura, M. A.; Ruiz, C. L.; Fehl, D. L.; Cooper, G. W.; Chandler, G.; Hahn, K. D.; Nelson, A. J.; Styron, J. D.; Torres, J. A.

    2014-11-01

    An accurate interpretation of DD or DT fusion neutron time-of-flight (nTOF) signals from current mode detectors employed at the Z-facility at Sandia National Laboratories requires that the instrument response functions (IRF's) be deconvolved from the measured nTOF signals. A calibration facility that produces detectable sub-ns radiation pulses is typically used to measure the IRF of such detectors. This work, however, reports on a simple method that utilizes cosmic radiation to measure the IRF of nTOF detectors, operated in pulse-counting mode. The characterizing metrics reported here are the throughput delay and full-width-at-half-maximum. This simple approach yields consistent IRF results with the same detectors calibrated in 2007 at a LINAC bremsstrahlung accelerator (Idaho State University). In particular, the IRF metrics from these two approaches and their dependence on the photomultipliers bias agree to within a few per cent. This information may thus be used to verify if the IRF for a given nTOF detector employed at Z has changed since its original current-mode calibration and warrants re-measurement.

  3. Comparison of Thermal Detector Arrays for Off-Axis THz Holography and Real-Time THz Imaging

    PubMed Central

    Hack, Erwin; Valzania, Lorenzo; Gäumann, Gregory; Shalaby, Mostafa; Hauri, Christoph P.; Zolliker, Peter

    2016-01-01

    In terahertz (THz) materials science, imaging by scanning prevails when low power THz sources are used. However, the application of array detectors operating with high power THz sources is increasingly reported. We compare the imaging properties of four different array detectors that are able to record THz radiation directly. Two micro-bolometer arrays are designed for infrared imaging in the 8–14 μm wavelength range, but are based on different absorber materials (i) vanadium oxide; (ii) amorphous silicon; (iii) a micro-bolometer array optimized for recording THz radiation based on silicon nitride; and (iv) a pyroelectric array detector for THz beam profile measurements. THz wavelengths of 96.5 μm, 118.8 μm, and 393.6 μm from a powerful far infrared laser were used to assess the technical performance in terms of signal to noise ratio, detector response and detectivity. The usefulness of the detectors for beam profiling and digital holography is assessed. Finally, the potential and limitation for real-time digital holography are discussed. PMID:26861341

  4. A technique for verifying the input response function of neutron time-of-flight scintillation detectors using cosmic rays

    SciTech Connect

    Bonura, M. A.; Cooper, G. W.; Nelson, A. J.; Styron, J. D.; Ruiz, C. L. Fehl, D. L.; Chandler, G.; Hahn, K. D.; Torres, J. A.

    2014-11-15

    An accurate interpretation of DD or DT fusion neutron time-of-flight (nTOF) signals from current mode detectors employed at the Z-facility at Sandia National Laboratories requires that the instrument response functions (IRF’s) be deconvolved from the measured nTOF signals. A calibration facility that produces detectable sub-ns radiation pulses is typically used to measure the IRF of such detectors. This work, however, reports on a simple method that utilizes cosmic radiation to measure the IRF of nTOF detectors, operated in pulse-counting mode. The characterizing metrics reported here are the throughput delay and full-width-at-half-maximum. This simple approach yields consistent IRF results with the same detectors calibrated in 2007 at a LINAC bremsstrahlung accelerator (Idaho State University). In particular, the IRF metrics from these two approaches and their dependence on the photomultipliers bias agree to within a few per cent. This information may thus be used to verify if the IRF for a given nTOF detector employed at Z has changed since its original current-mode calibration and warrants re-measurement.

  5. A New Neutron Time-of-Flight Detector for DT Yield and Ion-Temperature Measurements on OMEGA

    NASA Astrophysics Data System (ADS)

    Glebov, V. Yu.; Forrest, C. J.; Knauer, J. P.; Regan, S. P.; Sangster, T. C.; Stoeckl, C.

    2015-11-01

    A new neutron time-of-flight (nTOF) detector for DT yield and ion-temperature measurements in DT implosions on the OMEGA Laser System was designed, fabricated, tested, and calibrated. The goal of this detector is to provide a second line of sight for DT yield and ion-temperature measurements in the 1 ×1012 to 1014 yield range. The nTOF detector consists of a 40-mm-diam, 20-mm-thick BC-422Q(1%) scintillator coupled with a one-stage Photek PMT-140 photomultiplier tube. To avoid PMT saturation at high yields a neutral density filter ND1 is inserted between the scintillator and PMT. Both the scintillator and PMT are shielded from hard x rays by 5 mm of lead on all sides and 10 mm in the direction of the target. The nTOF detector is located at 15.8 m from target chamber center in the OMEGA Target Bay. The design details and calibration results of this nTOF detector in DT implosions on OMEGA will be presented. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  6. Analytical Calculation of the Lower Bound on Timing Resolution for PET Scintillation Detectors Comprising High-Aspect-Ratio Crystal Elements

    PubMed Central

    Cates, Joshua W.; Vinke, Ruud; Levin, Craig S.

    2015-01-01

    Excellent timing resolution is required to enhance the signal-to-noise ratio (SNR) gain available from the incorporation of time-of-flight (ToF) information in image reconstruction for positron emission tomography (PET). As the detector’s timing resolution improves, so does SNR, reconstructed image quality, and accuracy. This directly impacts the challenging detection and quantification tasks in the clinic. The recognition of these benefits has spurred efforts within the molecular imaging community to determine to what extent the timing resolution of scintillation detectors can be improved and develop near-term solutions for advancing ToF-PET. Presented in this work, is a method for calculating the Cramér-Rao lower bound (CRLB) on timing resolution for scintillation detectors with long crystal elements, where the influence of the variation in optical path length of scintillation light on achievable timing resolution is non-negligible. The presented formalism incorporates an accurate, analytical probability density function (PDF) of optical transit time within the crystal to obtain a purely mathematical expression of the CRLB with high-aspect-ratio (HAR) scintillation detectors. This approach enables the statistical limit on timing resolution performance to be analytically expressed for clinically-relevant PET scintillation detectors without requiring Monte Carlo simulation-generated photon transport time distributions. The analytically calculated optical transport PDF was compared with detailed light transport simulations, and excellent agreement was found between the two. The coincidence timing resolution (CTR) between two 3×3×20 mm3 LYSO:Ce crystals coupled to analogue SiPMs was experimentally measured to be 162±1 ps FWHM, approaching the analytically calculated lower bound within 6.5%. PMID:26083559

  7. Optimization of the Time Response of LaBr3(Ce) Detectors, and Its Dependence on Ce Concentration

    NASA Astrophysics Data System (ADS)

    Vedia, V.; Mach, H.; Fraile, L. M.; Lalkovski, S.; Udías, J. M.

    Fast inorganic scintillators that exhibit good spectroscopy performance, like LaBr3(Ce), are the crystals of choice for many applications; they play a crucial role in the Ultra Fast Timing technique by virtue of their good energy resolution and fast response [1]. This method, which is very sensitive to the LaBr3(Ce) time resolution, allows measurements of nuclear level lifetimes down to few ps range. There are indications that the nominal Ce concentration does strongly influence on the timing properties as well as it varies the photon yield and the energy resolution [2]. In this work we have searched for the best settings in order to optimize the time resolution of three cylindrical LaBr3(Ce) detectors equipped with crystals identical in volume and shape but with different Ce dopant concentration. The time resolution of every detector depends on the proper selection of the fast photomultiplier tube and the set up parameters that can be further optimized by fine-tuning of the Constant Fraction Discrimination (CFD) and the PMT bias voltage. Very good time resolution can be obtained with the ORTEC 935 CFD for very short time-delays. Timing properties of the three crystals were studied by delayed coincidence measurements against a reference BaF2 detector, whose time response is well known. The LaBr3(Ce) detector and the reference unit were placed in a close geometry with the radioactive source in between. We report timing results measured at the 60Co and 22Na energies.

  8. Analytical calculation of the lower bound on timing resolution for PET scintillation detectors comprising high-aspect-ratio crystal elements

    NASA Astrophysics Data System (ADS)

    Cates, Joshua W.; Vinke, Ruud; Levin, Craig S.

    2015-07-01

    Excellent timing resolution is required to enhance the signal-to-noise ratio (SNR) gain available from the incorporation of time-of-flight (ToF) information in image reconstruction for positron emission tomography (PET). As the detector’s timing resolution improves, so does SNR, reconstructed image quality, and accuracy. This directly impacts the challenging detection and quantification tasks in the clinic. The recognition of these benefits has spurred efforts within the molecular imaging community to determine to what extent the timing resolution of scintillation detectors can be improved and develop near-term solutions for advancing ToF-PET. Presented in this work, is a method for calculating the Cramér-Rao lower bound (CRLB) on timing resolution for scintillation detectors with long crystal elements, where the influence of the variation in optical path length of scintillation light on achievable timing resolution is non-negligible. The presented formalism incorporates an accurate, analytical probability density function (PDF) of optical transit time within the crystal to obtain a purely mathematical expression of the CRLB with high-aspect-ratio (HAR) scintillation detectors. This approach enables the statistical limit on timing resolution performance to be analytically expressed for clinically-relevant PET scintillation detectors without requiring Monte Carlo simulation-generated photon transport time distributions. The analytically calculated optical transport PDF was compared with detailed light transport simulations, and excellent agreement was found between the two. The coincidence timing resolution (CTR) between two 3× 3× 20 mm3 LYSO:Ce crystals coupled to analogue SiPMs was experimentally measured to be 162+/- 1 ps FWHM, approaching the analytically calculated lower bound within 6.5%.

  9. Growth responses of mature loblolly pine to dead wood manipulations

    Treesearch

    Michael D. Ulyshen; Scott Horn; James L. Hanula

    2012-01-01

    Large-scale manipulations of dead wood in mature Pinus taeda L. stands in the southeastern United States included a major one-time input of logs (fivefold increase in log volume) created by felling trees onsite, annual removals of all dead wood above ≥10 cm in diameter and ≥60 cm in length, and a reference in which no...

  10. Photon counting detector package optimized for laser time transfer with sub­-picosecond limiting precision and stability

    NASA Astrophysics Data System (ADS)

    Prochazka, Ivan; Blazej, Josef; Kodet, Jan

    2017-05-01

    The laser time transfer ground to space is an attractive technique to compare the ultra-stable clocks on ground and in space. The photon counting approach enables to reduce significantly the systematic errors of the measurement chain. For the space mission nominated for the next decade the precision and long term detection delay stability requirements are on sub-picosecond level. We have developed a new SPAD detector package for laser time transfer ground to space with extremely high timing precision and stability. It is based on 100 μm or 200 μm diameter K14 series SPAD chips. The device presented is primarily dedicated for a ground segment of the laser time transfer instrument chain. Applying such a detector the limiting precision of laser time transfer characterized by time deviation TDEV is well below 100 fs. The long term timing stability is better than 1 ps over days of operation. The detector package is constructed on a basis of electronics components for which the space qualified equivalents are available. The device construction, tests and results will be presented in detail.

  11. Dead of night.

    PubMed

    Balter, Leon

    2010-07-01

    Dead of Night, the first psychoanalytic horror film, was produced in England in 1945, immediately after the end of World War II--that is, after the English population had suffered systematic Nazi terror from imminent invasion, incessant aerial bombing, and rocket-bombs. This film continued the prewar format of horror films based on themes of the supernatural and the hubris and excesses of science. However, it introduced psychoanalysis as the science in question. The film is structured on two levels: a genteel English country weekend to which witty and urbane guests have been invited; and five horror stories told by the guests. Psychoanalytic insights into this film structure are used here to explain how the film induces horror in the audience.

  12. Time-resolved Fourier transform infrared spectroscopy of chemical reactions in solution using a focal plane array detector.

    PubMed

    Kaun, N; Vellekoop, M J; Lendl, B

    2006-11-01

    A Fourier transform infrared (FT-IR) microscope equipped with a single as well as a 64 x 64 element focal plane array MCT detector was used to measure chemical reaction taking place in a microstructured flow cell designed for time-resolved FT-IR spectroscopy. The flow cell allows transmission measurements through aqueous solutions and incorporates a microstructured mixing unit. This unit achieves lamination of the two input streams with a cross-section of 300 x 5 microm each, resulting in fast diffusion-controlled mixing of the two input streams. Microscopic measurement at defined positions along the outlet channel allows time-resolved information of the reaction taking place in the flow cell to be obtained. In this paper we show experimental results on the model reaction between formaldehyde and sulfite. Using the single-point MCT detector, high-quality FT-IR spectra could be obtained from a spot size of 80 x 200 microm whereas the FPA detector allowed recording light from an area of 260 x 260 microm focused on its 64 x 64 detector elements. Therefore, more closely spaced features could be discerned at the expense of a significantly lower signal-to-noise (S/N) ratio per spectrum. Multivariate curve resolution-alternating least squares was used to extract concentration profiles of the reacting species along the outlet channel axis.

  13. Real-time scintillation array dosimetry for radiotherapy: The advantages of photomultiplier detectors

    SciTech Connect

    Liu, Paul Z. Y.; Suchowerska, Natalka; Abolfathi, Peter; McKenzie, David R.

    2012-04-15

    Purpose: In this paper, a photomultiplier tube (PMT) array dosimetry system has been developed and tested for the real-time readout of multiple scintillation signals from fiber optic dosimeters. It provides array dosimetry with the advantages in sensitivity provided by a PMT, but without the need for a separate PMT for each detector element. Methods: The PMT array system consisted of a multianode PMT, a multichannel data acquisition system, housing and optic fiber connections suitable for clinical use. The reproducibility, channel uniformity, channel crosstalk, acquisition speed, and sensitivity of the PMT array were quantified using a constant light source. Its performance was compared to other readout systems used in scintillation dosimetry. An in vivo HDR brachytherapy treatment was used as an example of a clinical application of the dosimetry system to the measurement of dose at multiple sites in the rectum. The PMT array system was also tested in the pulsed beam of a linear accelerator to test its response speed and its application with two separate methods of Cerenkov background removal. Results: The PMT array dosimetry system was highly reproducible with a measurement uncertainty of 0.13% for a 10 s acquisition period. Optical crosstalk between neighboring channels was accounted for by omitting every second channel. A mathematical procedure was used to account for the crosstalk in next-neighbor channels. The speed and sensitivity of the PMT array system were found be superior to CCD cameras, allowing for measurement of more rapid changes in dose rate. This was further demonstrated by measuring the dose delivered by individual photon pulses of a linear accelerator beam. Conclusions: The PMT array system has advantages over CCD camera-based systems for the readout of scintillation light. It provided a more sensitive, more accurate, and faster response to meet the demands of future developments in treatment delivery.

  14. Real-time scintillation array dosimetry for radiotherapy: the advantages of photomultiplier detectors.

    PubMed

    Liu, Paul Z Y; Suchowerska, Natalka; Abolfathi, Peter; McKenzie, David R

    2012-04-01

    In this paper, a photomultiplier tube (PMT) array dosimetry system has been developed and tested for the real-time readout of multiple scintillation signals from fiber optic dosimeters. It provides array dosimetry with the advantages in sensitivity provided by a PMT, but without the need for a separate PMT for each detector element. The PMT array system consisted of a multianode PMT, a multichannel data acquisition system, housing and optic fiber connections suitable for clinical use. The reproducibility, channel uniformity, channel crosstalk, acquisition speed, and sensitivity of the PMT array were quantified using a constant light source. Its performance was compared to other readout systems used in scintillation dosimetry. An in vivo HDR brachytherapy treatment was used as an example of a clinical application of the dosimetry system to the measurement of dose at multiple sites in the rectum. The PMT array system was also tested in the pulsed beam of a linear accelerator to test its response speed and its application with two separate methods of Cerenkov background removal. The PMT array dosimetry system was highly reproducible with a measurement uncertainty of 0.13% for a 10 s acquisition period. Optical crosstalk between neighboring channels was accounted for by omitting every second channel. A mathematical procedure was used to account for the crosstalk in next-neighbor channels. The speed and sensitivity of the PMT array system were found be superior to CCD cameras, allowing for measurement of more rapid changes in dose rate. This was further demonstrated by measuring the dose delivered by individual photon pulses of a linear accelerator beam. The PMT array system has advantages over CCD camera-based systems for the readout of scintillation light. It provided a more sensitive, more accurate, and faster response to meet the demands of future developments in treatment delivery.

  15. Gaseous Detectors

    NASA Astrophysics Data System (ADS)

    Titov, Maxim

    Since long time, the compelling scientific goals of future high-energy physics experiments were a driving factor in the development of advanced detector technologies. A true innovation in detector instrumentation concepts came in 1968, with the development of a fully parallel readout for a large array of sensing elements - the Multi-Wire Proportional Chamber (MWPC), which earned Georges Charpak a Nobel prize in physics in 1992. Since that time radiation detection and imaging with fast gaseous detectors, capable of economically covering large detection volumes with low mass budget, have been playing an important role in many fields of physics. Advances in photolithography and microprocessing techniques in the chip industry during the past decade triggered a major transition in the field of gas detectors from wire structures to Micro-Pattern Gas Detector (MPGD) concepts, revolutionizing cell-size limitations for many gas detector applications. The high radiation resistance and excellent spatial and time resolution make them an invaluable tool to confront future detector challenges at the next generation of colliders. The design of the new micro-pattern devices appears suitable for industrial production. Novel structures where MPGDs are directly coupled to the CMOS pixel readout represent an exciting field allowing timing and charge measurements as well as precise spatial information in 3D. Originally developed for the high-energy physics, MPGD applications have expanded to nuclear physics, photon detection, astroparticle and neutrino physics, neutron detection, and medical imaging.

  16. X-ray analog pixel array detector for single synchrotron bunch time-resolved imaging.

    PubMed

    Koerner, Lucas J; Gruner, Sol M

    2011-03-01

    Dynamic X-ray studies can reach temporal resolutions limited by only the X-ray pulse duration if the detector is fast enough to segregate synchrotron pulses. An analog integrating pixel array detector with in-pixel storage and temporal resolution of around 150 ns, sufficient to isolate pulses, is presented. Analog integration minimizes count-rate limitations and in-pixel storage captures successive pulses. Fundamental tests of noise and linearity as well as high-speed laser measurements are shown. The detector resolved individual bunch trains at the Cornell High Energy Synchrotron Source at levels of up to 3.7 × 10(3) X-rays per pixel per train. When applied to turn-by-turn X-ray beam characterization, single-shot intensity measurements were made with a repeatability of 0.4% and horizontal oscillations of the positron cloud were detected.

  17. X-ray analog pixel array detector for single synchrotron bunch time-resolved imaging

    PubMed Central

    Koerner, Lucas J.; Gruner, Sol M.

    2011-01-01

    Dynamic X-ray studies can reach temporal resolutions limited by only the X-ray pulse duration if the detector is fast enough to segregate synchrotron pulses. An analog integrating pixel array detector with in-pixel storage and temporal resolution of around 150 ns, sufficient to isolate pulses, is presented. Analog integration minimizes count-rate limitations and in-pixel storage captures successive pulses. Fundamental tests of noise and linearity as well as high-speed laser measurements are shown. The detector resolved individual bunch trains at the Cornell High Energy Synchrotron Source at levels of up to 3.7 × 103 X-rays per pixel per train. When applied to turn-by-turn X-ray beam characterization, single-shot intensity measurements were made with a repeatability of 0.4% and horizontal oscillations of the positron cloud were detected. PMID:21335901

  18. Development of a pixel sensor with fine space-time resolution based on SOI technology for the ILC vertex detector

    NASA Astrophysics Data System (ADS)

    Ono, Shun; Togawa, Manabu; Tsuji, Ryoji; Mori, Teppei; Yamada, Miho; Arai, Yasuo; Tsuboyama, Toru; Hanagaki, Kazunori

    2017-02-01

    We have been developing a new monolithic pixel sensor with silicon-on-insulator (SOI) technology for the International Linear Collider (ILC) vertex detector system. The SOI monolithic pixel detector is realized using standard CMOS circuits fabricated on a fully depleted sensor layer. The new SOI sensor SOFIST can store both the position and timing information of charged particles in each 20×20 μm2 pixel. The position resolution is further improved by the position weighted with the charges spread to multiple pixels. The pixel also records the hit timing with an embedded time-stamp circuit. The sensor chip has column-parallel analog-to-digital conversion (ADC) circuits and zero-suppression logic for high-speed data readout. We are designing and evaluating some prototype sensor chips for optimizing and minimizing the pixel circuit.

  19. New Life From Dead Trees

    ERIC Educational Resources Information Center

    DeGraaf, Richard M.

    1978-01-01

    There are numerous bird species that will nest only in dead or dying trees. Current forestry practices include clearing forests of these snags, or dead trees. This practice is driving many species out of the forests. An illustrated example of bird succession in and on a tree is given. (MA)

  20. New Life From Dead Trees

    ERIC Educational Resources Information Center

    DeGraaf, Richard M.

    1978-01-01

    There are numerous bird species that will nest only in dead or dying trees. Current forestry practices include clearing forests of these snags, or dead trees. This practice is driving many species out of the forests. An illustrated example of bird succession in and on a tree is given. (MA)

  1. Reevaluating the dead donor rule.

    PubMed

    Collins, Mike

    2010-04-01

    The dead donor rule justifies current practice in organ procurement for transplantation and states that organ donors must be dead prior to donation. The majority of organ donors are diagnosed as having suffered brain death and hence are declared dead by neurological criteria. However, a significant amount of unrest in both the philosophical and the medical literature has surfaced since this practice began forty years ago. I argue that, first, declaring death by neurological criteria is both unreliable and unjustified but further, the ethical principles which themselves justify the dead donor rule are better served by abandoning that rule and instead allowing individuals who have suffered severe and irreversible brain damage to become organ donors, even though they are not yet dead and even though the removal of their organs would be the proximal cause of death.

  2. Multiple measurements of time of flight, position and energy deposit of ionizing particles by solid state detectors.

    NASA Astrophysics Data System (ADS)

    Codino, Antonio

    1997-03-01

    A telescope made of silicon strip detectors performing simultaneous measurements of position, time and energy deposit has been constructed and operated. The telescope has been tested with a pion beam of 4 GeV/c at the CERN Proton Synchrotron. The intrinsic time resolution of the telescope measured in the beam test is 61+/-7 ps. This unprecedented time resolution is achieved by the multiple sampling of the time of flight. Future developments of this telescope aiming at the construction of a new, analogous instrument of large sensitive area are considered (LATIN project).

  3. Development of a fast pixel array detector for use in microsecond time-resolved x-ray diffraction

    SciTech Connect

    Barna, S.L.; Gruner, S.M.; Shepherd, J.A.

    1995-08-01

    A large-area pixel x-ray detector is being developed to collect eight successive frames of wide dynamic range two-dimensional images at 200kHz rates. Such a detector, in conjunction with a synchrotron radiation x-ray source, will enable time-resolved x-ray studies of proteins and other materials on time scales which have previously been inaccessible. The detector will consist of an array of fully-depleted 150 micron square diodes connected to a CMOS integrated electronics layer with solder bump-bonding. During each framing period, the current resulting from the x-rays stopped in the diodes is integrated in the electronics layer, and then stored in one of eight storage capacitors underneath the pixel. After the last frame, the capacitors are read out at standard data transmission rates. The detector has been designed for a well-depth of at least 10,000 x-rays (at 20keV), and a noise level of one x-ray. Ultimately, the authors intend to construct a detector with over one million pixels (1024 by 1024). They present the results of their development effort and various features of the design. The electronics design is discussed, with special attention to the performance requirements. The choice and design of the detective diodes, as they relate to x-ray stopping power and charge collection, are presented. An analysis of various methods of bump bonding is also presented. Finally, the authors discuss the possible need for a radiation-blocking layer, to be placed between the electronics and the detective layer, and various methods they have pursued in the construction of such a layer.

  4. Spatial and temporal image characteristics of a real-time large area a-Se x-ray detector

    NASA Astrophysics Data System (ADS)

    Tousignant, Olivier; Demers, Yves; Laperriere, Luc; Mani, Habib; Gauthier, Philippe; Leboeuf, Jonathan

    2005-04-01

    Large area, real-time, amorphous selenium (a-Se) based Flat Panel Detectors (FPD) were recently equipped with low noise front end electronics. In full resolution, 14"x14" detectors (FPD14) and 9"x9" detectors (FPD9) show an electronic noise of 1400 electrons. To evaluate the positive impact of such low noise on image quality, a dedicated report on spatial characteristics (MTF, NPS and DQE) covering the low dose range from 0.6 μR to 12 μR per frame, will be presented in the first section of this paper. For one RQA5 beam quality, DQE corrected for lag extrapolated at zero spatial frequency was equal to 0.6 for quantum noise limited exposure and equal to 0.4 for 0.6 μR. Almost no difference was found between 1x1 and 2x2 resolution mode giving the opportunity to 1x1 fluoroscopy. Recent advances to reduce image temporal artifacts such as lag and ghost will make the second part of this paper. It is demonstrated that the most significant contribution to detector lag is coming from the PIN selenium structure. Above electric field of 10 V/μm charges release from traps following one x-ray exposure could not explain selenium lag. Active ghost correction based on deep trapped charge recombination was developed giving good preliminary results in showing no residual ghost for a high dose rate of 33 mR/min.

  5. Spectral representation: a core aspect of modelling the response characteristics of time-domain EMI mine detectors

    NASA Astrophysics Data System (ADS)

    West, G. F.; Bailey, R. C.

    2006-05-01

    Most modern EMI mine detectors can detect the very small conductive and/or ferromagnetic parts of typical mines with relative ease. However, they also respond significantly to certain soils that contain lossy ferromagnetic minerals. In some special environments such as ocean beaches, conductivity of the host soil may also cause a response. Characterizing and modelling both the various target response mechanisms and the EMI detectors quantitatively would be relatively straightforward if it were not for the fact that most modern EMI detectors operate in time domain and use different current waveforms and time gates to observe response. Furthermore, much of the information about targets and interferences and even instrumental spectral limitations is observational rather than analytical data. In this paper, we put forward a spectral representation method that can be incorporated into both EMI data gathering and instrument modelling and which facilitates efficient quantitative simulation of arbitrary time- domain detection systems. The methodology and examples of its use are presented. Pure induction response from the ground is modelled with a sum-over-N-elements transfer function in which the kernel elements are single pole, pure damping responses which are log-spaced over the spectral range of interest. Instrument transfer functions can be described with a standard sparse pole and zero representation (located anywhere in the damped frequency half plane), if required. Model fitting techniques employing generalized inversion controls are used to go back and forth between frequency and time domain and the set of model parameters.

  6. Test of Ultra Fast Silicon Detectors for picosecond time measurements with a new multipurpose read-out board

    NASA Astrophysics Data System (ADS)

    Minafra, N.; Al Ghoul, H.; Arcidiacono, R.; Cartiglia, N.; Forthomme, L.; Mulargia, R.; Obertino, M.; Royon, C.

    2017-09-01

    Ultra Fast Silicon Detectors (UFSD) are sensors optimized for timing measurements employing a thin multiplication layer to increase the output signal. A multipurpose read-out board hosting a low-cost, low-power fast amplifier was designed at the University of Kansas and tested at the European Organization for Nuclear Research (CERN) using a 180 GeV pion beam. The amplifier has been designed to read out a wide range of detectors and it was optimized in this test for the UFSD output signal. In this paper we report the results of the experimental tests using 50 μm thick UFSD with a sensitive area of 1 . 4mm2. A timing precision below 30 ps was achieved.

  7. Static and Time-Resolved 10-1000 ke V X-Ray Imaging Detector Options for NIF

    SciTech Connect

    Landen, O; Bell, P; McDonald, J; Park, H; Weber, F; Moody, J; Lowry, M; Stewart, R

    2004-04-15

    High energy (> 10 keV) x-ray self-emission imaging and radiography will be essential components of many NIF High Energy Density Physics experiments. In preparation for such experiments, we have evaluated the pros and cons of various static (x-ray film, bare CCD, and scintillator + CCD) and time-resolved (streaked and gated) 10-1000 keV detectors.

  8. Static and time-resolved 10-1000 keV x-ray imaging detector options for NIF

    SciTech Connect

    Landen, O.L.; Bell, P.M.; McDonald, J.W.; Park, H.-S.; Weber, F.; Moody, J.D.; Lowry, M.E.; Stewart, R.E.

    2004-10-01

    High energy (>10 keV) x-ray self-emission imaging and radiography will be essential components of many NIF high energy density physics experiments. In preparation for such experiments, we have evaluated the pros and cons of various static [x-ray film, bare charge-coupled device (CCD), and scintillator + CCD] and time-resolved (streaked and gated) 10-1000 keV detectors.

  9. Time walk correction for TOF-PET detectors based on a monolithic scintillation crystal coupled to a photosensor array

    NASA Astrophysics Data System (ADS)

    Vinke, R.; Löhner, H.; Schaart, D. R.; van Dam, H. T.; Seifert, S.; Beekman, F. J.; Dendooven, P.

    2010-09-01

    When optimizing the timing performance of a time-of-flight positron emission tomography (TOF-PET) detector based on a monolithic scintillation crystal coupled to a photosensor array, time walk as a function of annihilation photon interaction location inside the crystal needs to be considered. In order to determine the 3D spatial coordinates of the annihilation photon interaction location, a maximum likelihood estimation algorithm was developed, based on a detector characterization by a scan of a 511 keV photon beam across the front and one of the side surfaces of the crystal. The time walk effect was investigated using a 20 mm×20 mm×12 mm LYSO crystal coupled to a fast 4×4 multi-anode photomultiplier tube (MAPMT). In the plane parallel to the photosensor array, a spatial resolution of 2.4 mm FWHM is obtained. In the direction perpendicular to the MAPMT (depth-of-interaction, DOI), the resolution ranges from 2.3 mm FWHM near the MAPMT to 4 mm FWHM at a distance of 10 mm. These resolutions are uncorrected for the ˜1 mm beam diameter. A coincidence timing resolution of 358 ps FWHM is obtained in coincidence with a BaF 2 detector. A time walk depending on the 3D annihilation photon interaction location is observed. Throughout the crystal, the time walk spans a range of 100 ps. Calibration of the time walk vs. interaction location allows an event-by-event correction of the time walk.

  10. ON HYDRODYNAMIC MOTIONS IN DEAD ZONES

    SciTech Connect

    Oishi, Jeffrey S.; Mac Low, Mordecai-Mark E-mail: mordecai@amnh.or

    2009-10-20

    We investigate fluid motions near the midplane of vertically stratified accretion disks with highly resistive midplanes. In such disks, the magnetorotational instability drives turbulence in thin layers surrounding a resistive, stable dead zone. The turbulent layers in turn drive motions in the dead zone. We examine the properties of these motions using three-dimensional, stratified, local, shearing-box, non-ideal, magnetohydrodynamical simulations. Although the turbulence in the active zones provides a source of vorticity to the midplane, no evidence for coherent vortices is found in our simulations. It appears that this is because of strong vertical oscillations in the dead zone. By analyzing time series of azimuthally averaged flow quantities, we identify an axisymmetric wave mode particular to models with dead zones. This mode is reduced in amplitude, but not suppressed entirely, by changing the equation of state from isothermal to ideal. These waves are too low frequency to affect sedimentation of dust to the midplane, but may have significance for the gravitational stability of the resulting midplane dust layers.

  11. Detector Data Simulation and Filtering Strategy for the European Laser Timing (ELT) Experiment On-board ACES

    NASA Astrophysics Data System (ADS)

    Bamann, Christoph; Schlicht, Anja; Hugentobler, Urs; Pühl, Magdalena

    2015-04-01

    Due to the rapid progress of frequency standards in the optical domain and increasingly demanding applications in metrology and fundamental physics studies, accuracy requirements on frequency and time transfer are continuously increasing. Most present satellite based clock comparison systems work in the microwave domain and are based on GPS and TWSTFT (Two-Way Satellite Time and Frequency Transfer). Recently, systems such as LASSO (LAser Synchronization from a Stationary Orbit) and T2L2 (Time Transfer by Laser Link) promised even better performance in the optical domain. In 2016 the ESA mission ACES (Atomic Clock Ensemble in Space) will bring a new generation of atomic clocks into the microgravity environment of the ISS, which will distribute a stable and accurate time base. In the frame of this mission an optical link called ELT (European Laser Timing) is presently under study, which is subject of our work. The on-board hardware of ELT consists of a corner cube retro-reflector (CCR), a single-photon avalanche diode (SPAD), and an event timer connected to the ACES time scale. The SPAD detects laser pulses fired towards the payload and the CCR reflects these pulses back to the ground station. The detection dates are recorded in the ACES time scale, while the two-way time of flight can be used for precise ranging. Consequently, time transfer and clock analysis can be performed based on data triplets comprising the time of transmission of a laser pulse, its time of reception at the ELT-detector and its time of reception back at the station-detector. We present simulations of these triplets based on simple ISS orbits including preset attitude and accurate Earth orientation data. In addition, we consider experimentally derived detector, reflector, and background noise characteristics as well as simulations of the ACES clocks. The ELT data center, which will be hosted by our institution, will have to extract the data triplets from the large amount of noisy detector dates

  12. A study of cooling time reduction of interferometric cryogenic gravitational wave detectors using a high-emissivity coating

    SciTech Connect

    Sakakibara, Y.; Yamamoto, K.; Chen, D.; Tokoku, C.; Uchiyama, T.; Ohashi, M.; Kuroda, K.; Kimura, N.; Suzuki, T.; Koike, S.

    2014-01-29

    In interferometric cryogenic gravitational wave detectors, there are plans to cool mirrors and their suspension systems (payloads) in order to reduce thermal noise, that is, one of the fundamental noise sources. Because of the large payload masses (several hundred kg in total) and their thermal isolation, a cooling time of several months is required. Our calculation shows that a high-emissivity coating (e.g. a diamond-like carbon (DLC) coating) can reduce the cooling time effectively by enhancing radiation heat transfer. Here, we have experimentally verified the effect of the DLC coating on the reduction of the cooling time.

  13. Test-beam results of a silicon pixel detector with Time-over-Threshold read-out having ultra-precise time resolution

    NASA Astrophysics Data System (ADS)

    Aglieri Rinella, G.; Cortina Gil, E.; Fiorini, M.; Kaplon, J.; Kluge, A.; Marchetto, F.; Albarran, M. E. Martin; Morel, M.; Noy, M.; Perktold, L.; Tiuraniem, S.; Velghe, B.

    2015-12-01

    A time-tagging hybrid silicon pixel detector developed for beam tracking in the NA62 experiment has been tested in a dedicated test-beam at CERN with 10 GeV/c hadrons. Measurements include time resolution, detection efficiency and charge sharing between pixels, as well as effects due to bias voltage variations. A time resolution of less than 150 ps has been measured with a 200 μm thick silicon sensor, using an on-pixel amplifier-discriminator and an end-of-column DLL-based time-to-digital converter.

  14. Silicon Photomultiplier-Based Multi-Channel Gamma Ray Detector Using the Dynamic Time-Over-Threshold Method

    NASA Astrophysics Data System (ADS)

    Nakamura, Y.; Shimazoe, K.; Takahashi, H.

    2016-02-01

    Silicon photomultipliers (SiPMs), which are a relatively new type of photon detector, have received more attention in the fields of nuclear medicine and high-energy physics because of their compactness and high gain up to 106. In this work, a SiPM-based multi-channel gamma ray detector with individual read out based on the dynamic time-over-threshold (dToT) method is implemented and demonstrated as an elemental material for large-area gamma ray imager applications. The detector consists of 64 channels of KETEK SiPM PM6660 (6 × 6 mm2 containing 10,000 micro-cells of 60 × 60 μm2) coupled to an 8 × 8 array of high-energy resolution Gd3(Al,Ga)5O12(Ce) (HR-GAGG) crystals (10 × 10 × 10 mm3) segmented by a 1 mm thick BaSO4 reflector. To produce a digital pulse containing linear energy information, the dToT-based read-out circuit consists of a CR-RC shaping amplifier (2.2 μs) and comparator with a feedback component. By modelling the pulse of the SiPM, the light output, and the CR-RC shaping amplifier, the integral-non-linearity (INL) was numerically calculated in terms of the delay time and the time constant of dynamic threshold movement. The experimental results of the averaged INL and energy resolution were 5.8±1.6% and the full-width-at-half-maximum (FWHM) of 7.4±0.9% at 662 keV, respectively. The 64-channel single-mode detector module was successfully implemented, demonstrating potential for its use as an elemental material for large-area gamma ray imaging applications.

  15. Highly multiplexed signal readout for a time-of-flight positron emission tomography detector based on silicon photomultipliers.

    PubMed

    Cates, Joshua W; Bieniosek, Matthew F; Levin, Craig S

    2017-01-01

    Maintaining excellent timing resolution in the generation of silicon photomultiplier (SiPM)-based time-of-flight positron emission tomography (TOF-PET) systems requires a large number of high-speed, high-bandwidth electronic channels and components. To minimize the cost and complexity of a system's back-end architecture and data acquisition, many analog signals are often multiplexed to fewer channels using techniques that encode timing, energy, and position information. With progress in the development SiPMs having lower dark noise, after pulsing, and cross talk along with higher photodetection efficiency, a coincidence timing resolution (CTR) well below 200 ps FWHM is now easily achievable in single pixel, bench-top setups using 20-mm length, lutetium-based inorganic scintillators. However, multiplexing the output of many SiPMs to a single channel will significantly degrade CTR without appropriate signal processing. We test the performance of a PET detector readout concept that multiplexes 16 SiPMs to two channels. One channel provides timing information with fast comparators, and the second channel encodes both position and energy information in a time-over-threshold-based pulse sequence. This multiplexing readout concept was constructed with discrete components to process signals from a [Formula: see text] array of SensL MicroFC-30035 SiPMs coupled to [Formula: see text] Lu1.8Gd0.2SiO5 (LGSO):Ce (0.025 mol. %) scintillators. This readout method yielded a calibrated, global energy resolution of 15.3% FWHM at 511 keV with a CTR of [Formula: see text] FWHM between the 16-pixel multiplexed detector array and a [Formula: see text] LGSO-SiPM reference detector. In summary, results indicate this multiplexing scheme is a scalable readout technique that provides excellent coincidence timing performance.

  16. A new front-end ASIC for GEM detectors with time and charge measurement capabilities

    NASA Astrophysics Data System (ADS)

    Ciciriello, F.; Corsi, F.; De Robertis, G.; Felici, G.; Loddo, F.; Marzocca, C.; Matarrese, G.; Ranieri, A.

    2016-07-01

    A 32 channel CMOS front-end ASIC has been designed to read out the GEM detectors intended to be used for beam monitoring in a new proton-therapy facility currently under construction. In order to improve the spatial resolution by exploiting charge centroid algorithms, the analog channels, based on the classic CSA+shaper architecture, are equipped with a peak detector (PD) which works as an analog memory during the read-out phase. The outputs of the PDs are multiplexed towards an integrated 8-bit subranging ADC. An accurate trigger signal marks the arrival of a valid event and is generated by fast-ORing the outputs of 32 voltage discriminators which compare the shaper outputs with a programmable threshold. The digital part of the ASIC manages the read-out of the channels, the A/D conversion and the configuration of the ASIC. A 100 Mbit/s LVDS serial link is used for data communication. The sensitivity of the analog channel is 15 mV/fC and the dynamic range is 80 fC. The simulated ENC is about 650 e- for a detector capacitance of 10 pF.

  17. Time-Resolved Diffuse Optical Spectroscopy and Imaging Using Solid-State Detectors: Characteristics, Present Status, and Research Challenges.

    PubMed

    Alayed, Mrwan; Deen, M Jamal

    2017-09-14

    Diffuse optical spectroscopy (DOS) and diffuse optical imaging (DOI) are emerging non-invasive imaging modalities that have wide spread potential applications in many fields, particularly for structural and functional imaging in medicine. In this article, we review time-resolved diffuse optical imaging (TR-DOI) systems using solid-state detectors with a special focus on Single-Photon Avalanche Diodes (SPADs) and Silicon Photomultipliers (SiPMs). These TR-DOI systems can be categorized into two types based on the operation mode of the detector (free-running or time-gated). For the TR-DOI prototypes, the physical concepts, main components, figures-of-merit of detectors, and evaluation parameters are described. The performance of TR-DOI prototypes is evaluated according to the parameters used in common protocols to test DOI systems particularly basic instrumental performance (BIP). In addition, the potential features of SPADs and SiPMs to improve TR-DOI systems and expand their applications in the foreseeable future are discussed. Lastly, research challenges and future developments for TR-DOI are discussed for each component in the prototype separately and also for the entire system.

  18. Time-Resolved Diffuse Optical Spectroscopy and Imaging Using Solid-State Detectors: Characteristics, Present Status, and Research Challenges

    PubMed Central

    Alayed, Mrwan

    2017-01-01

    Diffuse optical spectroscopy (DOS) and diffuse optical imaging (DOI) are emerging non-invasive imaging modalities that have wide spread potential applications in many fields, particularly for structural and functional imaging in medicine. In this article, we review time-resolved diffuse optical imaging (TR-DOI) systems using solid-state detectors with a special focus on Single-Photon Avalanche Diodes (SPADs) and Silicon Photomultipliers (SiPMs). These TR-DOI systems can be categorized into two types based on the operation mode of the detector (free-running or time-gated). For the TR-DOI prototypes, the physical concepts, main components, figures-of-merit of detectors, and evaluation parameters are described. The performance of TR-DOI prototypes is evaluated according to the parameters used in common protocols to test DOI systems particularly basic instrumental performance (BIP). In addition, the potential features of SPADs and SiPMs to improve TR-DOI systems and expand their applications in the foreseeable future are discussed. Lastly, research challenges and future developments for TR-DOI are discussed for each component in the prototype separately and also for the entire system. PMID:28906462

  19. Real-time in vivo rectal wall dosimetry using plastic scintillation detectors for patients with prostate cancer

    PubMed Central

    Wootton, Landon; Kudchadker, Rajat; Lee, Andrew; Beddar, Sam

    2014-01-01

    We designed and constructed an in vivo dosimetry system using plastic scintillation detectors (PSDs) to monitor dose to the rectal wall in patients undergoing intensity-modulated radiation therapy for prostate cancer. Five patients were enrolled in an Institutional Review Board–approved protocol for twice weekly in vivo dose monitoring with our system, resulting in a total of 142 in vivo dose measurements. PSDs were attached to the surface of endorectal balloons used for prostate immobilization to place the PSDs in contact with the rectal wall. Absorbed dose was measured in real time and the total measured dose was compared with the dose calculated by the treatment planning system on the daily CT image dataset. The mean difference between measured and calculated doses for the entire patient population was −0.4% (standard deviation 2.8%). The mean difference between daily measured and calculated doses for each patient ranged from −3.3% to 3.3% (standard deviation ranged from 5.6% to 7.1% for 4 patients and was 14.0% for the last, for whom optimal positioning of the detector was difficult owing to the patient’s large size). Patients tolerated the detectors well and the treatment workflow was not compromised. Overall, PSDs performed well as in vivo dosimeters, providing excellent accuracy, real-time measurement, and reusability. PMID:24434775

  20. PANDORA, a large volume low-energy neutron detector with real-time neutron-gamma discrimination

    NASA Astrophysics Data System (ADS)

    Stuhl, L.; Sasano, M.; Yako, K.; Yasuda, J.; Baba, H.; Ota, S.; Uesaka, T.

    2017-09-01

    The PANDORA (Particle Analyzer Neutron Detector Of Real-time Acquisition) system, which was developed for use in inverse kinematics experiments with unstable isotope beams, is a neutron detector based on a plastic scintillator coupled to a digital readout. PANDORA can be used for any reaction study involving the emission of low energy neutrons (100 keV-10 MeV) where background suppression and an increased signal-to-noise ratio are crucial. The digital readout system provides an opportunity for pulse shape discrimination (PSD) of the detected particles as well as intelligent triggering based on PSD. The figure of merit results of PANDORA are compared to the data in literature. Using PANDORA, 91 ± 1% of all detected neutrons can be separated, while 91 ± 1% of the detected gamma rays can be excluded, reducing the gamma ray background by one order of magnitude.