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Sample records for digitized pulse shape

  1. Preliminary results of Digital Pulse Shape Acquisition from Chimera

    Energy Technology Data Exchange (ETDEWEB)

    Alderighi, D.M.; Sechi, G. [INFN Milano and IASF, CNR, Milano (France); Anzalone, A.; Cavallaro, S.; Giustolisi, F.; Laguidara, E.; Lanzalone, G.; Porto, F. [Catania Univ., LNS and Dipartimento di Fisica (France); Bassini, R.; Boiano, C.; Guazzoni, P.; Russo, S.; Sassi, M.; Zetta, L. [Milano Univ., INFN and Dipartimento di Fisica (Italy); Cardella, G.; Defilippo, S.E.; Lanzano, G.; Paganod, A.; Papa, M.; Pirrone, S.; Politi, G. [Catania Univ., INFN and Dipartimento di Fisica (Italy); Geraci, E. [Bologna Univ., INFN and Dipartimento di Fisica (Italy)

    2003-07-01

    A 100 MS/s 14-bit Sampling Analog-to-Digital converter has been used to perform digital pulse-shape acquisition of signals collected from CHIMERA telescopes. The signals from a typical CHIMERA detection cell have been collected using both a standard CHIMERA electronic chain up to the amplifier, and a very simple analog front end, basically reduced to the preamplifier. The preliminary on-beam results are presented. (authors)

  2. Digital pulse-shape processing for CdTe detectors

    CERN Document Server

    Bargholtz, C; Maartensson, L; Wachtmeister, S

    2001-01-01

    CdTe detectors suffer from low photo-peak efficiency and poor energy resolution. These problems are due to the drift properties of charge carriers in CdTe where particularly the holes have small mobility and trapping time. This is reflected in the amplitude and the shape of the detector output. To improve this situation a digital method is introduced where a sampling ADC is used to make a detailed measurement of the time evolution of the pulse. The measured pulse shape is fitted with a model. For the detector under study a model taking hole trapping into account significantly improves the photo-peak efficiency. The description of the hole component is, however, not fully satisfactory since for pulses with a large hole contribution a broadening of the full-energy peak occurs. Allowing for inhomogeneities in the detector material within the model partially remedies this deficiency.

  3. General purpose pulse shape analysis for fast scintillators implemented in digital readout electronics

    Science.gov (United States)

    Asztalos, Stephen J.; Hennig, Wolfgang; Warburton, William K.

    2016-01-01

    Pulse shape discrimination applied to certain fast scintillators is usually performed offline. In sufficiently high-event rate environments data transfer and storage become problematic, which suggests a different analysis approach. In response, we have implemented a general purpose pulse shape analysis algorithm in the XIA Pixie-500 and Pixie-500 Express digital spectrometers. In this implementation waveforms are processed in real time, reducing the pulse characteristics to a few pulse shape analysis parameters and eliminating time-consuming waveform transfer and storage. We discuss implementation of these features, their advantages, necessary trade-offs and performance. Measurements from bench top and experimental setups using fast scintillators and XIA processors are presented.

  4. Characterization of liquid scintillation detector (BC-501A) and digital pulse shape discrimination (DPSD) system

    Energy Technology Data Exchange (ETDEWEB)

    Lombigit, L., E-mail: lojius@nm.gov.my; Yussup, N., E-mail: nolida@nm.gov.my; Ibrahim, Maslina Mohd; Rahman, Nur Aira Abd; Rawi, M. Z. M. [Instrumentation Group, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia)

    2015-04-29

    A digital n/γ pulse shape discrimination (PSD) system is currently under development at Instrumentation and Automation Centre, Malaysian Nuclear Agency. This system aims at simultaneous detection of fast neutron and gamma ray in mixed radiations environment. This work reports the system characterization performed on the liquid scintillation detector (BC-501A) and digital pulse shape discrimination (DPSD) system. The characterization involves measurement of electron light output from the BC-501A detector and energy channels calibration of the pulse height spectra acquired with DPSD system using set of photon reference sources. The main goal of this experiment is to calibrate the ADC channel of our DPSD system, characterized the BC-501 detector and find the position of Compton edge which later could be used as threshold for the n/γ PSD experiment. The detector resolution however is worse as compared to other published data but it is expected as our detector has a smaller active volume.

  5. Effects of irradiation of energetic heavy ions on digital pulse shape analysis with silicon detectors

    Science.gov (United States)

    Barlini, S.; Carboni, S.; Bardelli, L.; Le Neindre, N.; Bini, M.; Borderie, B.; Bougault, R.; Casini, G.; Edelbruck, P.; Olmi, A.; Pasquali, G.; Poggi, G.; Rivet, M. F.; Stefanini, A. A.; Baiocco, G.; Berjillos, R.; Bonnet, E.; Bruno, M.; Chbihi, A.; Cruceru, I.; Degerlier, M.; Dueñas, J. A.; Galichet, E.; Gramegna, F.; Kordyasz, A.; Kozik, T.; Kravchuk, V. L.; Lopez, O.; Marchi, T.; Martel, I.; Morelli, L.; Parlog, M.; Piantelli, S.; Petrascu, H.; Rosato, E.; Seredov, V.; Vient, E.; Vigilante, M.; Fazia Collaboration

    2013-04-01

    The next generation of 4π detector arrays for heavy ion studies will largely use Pulse Shape Analysis to push the performance of silicon detectors with respect to ion identification. Energy resolution and pulse shape identification capabilities of silicon detectors under prolonged irradiation by energetic heavy ions have thus become a major issue. In this framework, we have studied the effects of irradiation by energetic heavy ions on the response of neutron transmutation doped (nTD) silicon detectors. Sizeable effects on the amplitude and the risetime of the charge signal have been found for detectors irradiated with large fluences of stopped heavy ions, while much weaker effects were observed by punching-through ions. The robustness of ion identification based on digital pulse shape techniques has been evaluated.

  6. Digital liquid-scintillation counting and effective pulse-shape discrimination with artificial neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Langrock, Gert; Wiehl, Norbert; Kling, Hans-Otto; Mendel, Matthias; Naehler, Andrea; Tharun, Udo; Eberhardt, Klaus; Trautmann, Norbert; Kratz, Jens Volker [Mainz Univ. (Germany). Inst. fuer Kernchemie; Omtvedt, Jon-Petter [Oslo Univ. (Norway). Dept. of Chemistry; Skarnemark, Gunnar [Chalmers Univ. of Technology, Goeteborg (Sweden)

    2015-05-01

    A typical problem in low-level liquid scintillation (LS) counting is the identification of α particles in the presence of a high background of β and γ particles. Especially the occurrence of β-β and β-γ pile-ups may prevent the unambiguous identification of an α signal by commonly used analog electronics. In this case, pulse-shape discrimination (PSD) and pile-up rejection (PUR) units show an insufficient performance. This problem was also observed in own earlier experiments on the chemical behaviour of transactinide elements using the liquid-liquid extraction system SISAK in combination with LS counting. α-particle signals from the decay of the transactinides could not be unambiguously assigned. However, the availability of instruments for the digital recording of LS pulses changes the situation and provides possibilities for new approaches in the treatment of LS pulse shapes. In a SISAK experiment performed at PSI, Villigen, a fast transient recorder, a PC card with oscilloscope characteristics and a sampling rate of 1 giga samples s{sup -1} (1 ns per point), was used for the first time to record LS signals. It turned out, that the recorded signals were predominantly α β-β and β-γ pile up, and fission events. This paper describes the subsequent development and use of artificial neural networks (ANN) based on the method of 'back-propagation of errors' to automatically distinguish between different pulse shapes. Such networks can 'learn' pulse shapes and classify hitherto unknown pulses correctly after a learning period. The results show that ANN in combination with fast digital recording of pulse shapes can be a powerful tool in LS spectrometry even at high background count rates.

  7. Comparison Between Digital and Analog Pulse Shape Discrimination Techniques For Neutron and Gamma Ray Separation

    Energy Technology Data Exchange (ETDEWEB)

    R. Aryaeinejad; John K. Hartwell

    2005-11-01

    Recent advancement in digital signal processing (DSP) using fast processors and computer makes it possible to be used in pulse shape discrimination applications. In this study, we have investigated the feasibility of using a DSP to distinguish between the neutrons and gamma rays by the shape of their pulses in a liquid scintillator detector (BC501), and have investigated pulse shape-based techniques to improve the resolution performance of room-temperature cadmium zinc telluride (CZT) detectors. For the neutron/gamma discrimination, the advantage of using a DSP over the analog method is that in analog system two separate charge-sensitive ADC's are required. One ADC is used to integrate the beginning of the pulse risetime while the second ADC is for integrating the tail part. Using a DSP eliminates the need for separate ADCs as one can easily get the integration of two parts of the pulse from the digital waveforms. This work describes the performance of these DSP techniques and compares the results with the analog method.

  8. Design of FIR digital filters for pulse shaping and channel equalization using time-domain optimization

    Science.gov (United States)

    Houts, R. C.; Vaughn, G. L.

    1974-01-01

    Three algorithms are developed for designing finite impulse response digital filters to be used for pulse shaping and channel equalization. The first is the Minimax algorithm which uses linear programming to design a frequency-sampling filter with a pulse shape that approximates the specification in a minimax sense. Design examples are included which accurately approximate a specified impulse response with a maximum error of 0.03 using only six resonators. The second algorithm is an extension of the Minimax algorithm to design preset equalizers for channels with known impulse responses. Both transversal and frequency-sampling equalizer structures are designed to produce a minimax approximation of a specified channel output waveform. Examples of these designs are compared as to the accuracy of the approximation, the resultant intersymbol interference (ISI), and the required transmitted energy. While the transversal designs are slightly more accurate, the frequency-sampling designs using six resonators have smaller ISI and energy values.

  9. Real-time digital signal processor implementation of self-calibrating pulse-shape discriminator for high purity germanium

    CERN Document Server

    Suarez, R; Aalseth, C E; Hossbach, T W; Miley, H S

    2007-01-01

    Pulse-shape analysis of the ionization signals from germanium gamma-ray spectrometers is a method for obtaining information that can characterize an event beyond just the total energy deposited in the crystal. However, as typically employed, this method is data-intensive requiring the digitization, transfer, and recording of electronic signals from the spectrometer. A hardware realization of a real-time digital signal processor for implementing a parametric pulse shape is presented. Specifically, a previously developed method for distinguishing between single-site and multi-site gamma-ray interactions is demonstrated in an on-line digital signal processor, compared with the original off-line pulse-shape analysis routine, and shown to have no significant difference. Reduction of the amount of the recorded information per event is shown to translate into higher duty-cycle data acquisition rates while retaining the benefits of additional event characterization from pulse-shape analysis.

  10. Digital pulse-shape analysis with a TRACE early silicon prototype

    Energy Technology Data Exchange (ETDEWEB)

    Mengoni, D., E-mail: daniele.mengoni@pd.infn.it [Dipartimento di Fisica e Astronomia, Università di Padova, via F. Marzolo, 8 - 35131 Padova (Italy); INFN Padova, via Marzolo 8 - 35131 Padova (Italy); Dueñas, J.A. [Departamento de Física Aplicada, FCCEE Universidad de Huelva, 21071 Huelva (Spain); Assié, M. [Institut de Physique Nucléaire, Université Paris-Sud-11-CNRS/IN2P3, 91406 Orsay (France); Boiano, C. [INFN Milano, Via Celoria, 16 - 20133 Milano (Italy); John, P.R. [Dipartimento di Fisica e Astronomia, Università di Padova, via F. Marzolo, 8 - 35131 Padova (Italy); INFN Padova, via Marzolo 8 - 35131 Padova (Italy); Aliaga, R.J. [Universidad Politécnica de Valencia, CSIC, CIEMAT, I3M, Valencia (Spain); Beaumel, D. [Institut de Physique Nucléaire, Université Paris-Sud-11-CNRS/IN2P3, 91406 Orsay (France); Capra, S. [INFN Milano, Via Celoria, 16 - 20133 Milano (Italy); Gadea, A. [Instituto de Fisica Corpuscular, CSIC – Universitat de Valencia, Paterna, Valencia (Spain); Gonzáles, V. [Departamento de Ingeniería Electrónica, Universitat de Valencia, Burjassot, Valencia (Spain); Gottardo, A. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Legnaro (Padova) (Italy); Grassi, L. [Dipartimento di Fisica e Astronomia, Università di Padova, via F. Marzolo, 8 - 35131 Padova (Italy); INFN Padova, via Marzolo 8 - 35131 Padova (Italy); Herrero-Bosch, V. [Universidad Politécnica de Valencia, CSIC, CIEMAT, I3M, Valencia (Spain); Houdy, T. [Faculté des Sciences, Université Paris-Sud, 91405 Orsay (France); and others

    2014-11-11

    A highly segmented silicon-pad detector prototype has been tested to explore the performance of the digital pulse shape analysis in the discrimination of the particles reaching the silicon detector. For the first time a 200 μm thin silicon detector, grown using an ordinary floating zone technique, has been shown to exhibit a level discrimination thanks to the fine segmentation. Light-charged particles down to few MeV have been separated, including their punch-through. A coaxial HPGe detector in time coincidence has further confirmed the quality of the particle discrimination.

  11. Digital pulse-shape analysis with a TRACE early silicon prototype

    Science.gov (United States)

    Mengoni, D.; Dueñas, J. A.; Assié, M.; Boiano, C.; John, P. R.; Aliaga, R. J.; Beaumel, D.; Capra, S.; Gadea, A.; Gonzáles, V.; Gottardo, A.; Grassi, L.; Herrero-Bosch, V.; Houdy, T.; Martel, I.; Parkar, V. V.; Perez-Vidal, R.; Pullia, A.; Sanchis, E.; Triossi, A.; Valiente Dobón, J. J.

    2014-11-01

    A highly segmented silicon-pad detector prototype has been tested to explore the performance of the digital pulse shape analysis in the discrimination of the particles reaching the silicon detector. For the first time a 200 μm thin silicon detector, grown using an ordinary floating zone technique, has been shown to exhibit a level discrimination thanks to the fine segmentation. Light-charged particles down to few MeV have been separated, including their punch-through. A coaxial HPGe detector in time coincidence has further confirmed the quality of the particle discrimination.

  12. Fast neutron flux analyzer with real-time digital pulse shape discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Ivanova, A.A., E-mail: a.a.ivanova@inp.nsk.su [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Zubarev, P.V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 630092 Novosibirsk (Russian Federation); Ivanenko, S.V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Khilchenko, A.D. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 630092 Novosibirsk (Russian Federation); Kotelnikov, A.I. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Polosatkin, S.V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 630092 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Puryga, E.A.; Shvyrev, V.G. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 630092 Novosibirsk (Russian Federation); Sulyaev, Yu.S. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

    2016-08-11

    Investigation of subthermonuclear plasma confinement and heating in magnetic fusion devices such as GOL–3 and GDT at the Budker Institute (Novosibirsk, Russia) requires sophisticated equipment for neutron-, gamma- diagnostics and upgrading data acquisition systems with online data processing. Measurement of fast neutron flux with stilbene scintillation detectors raised the problem of discrimination of the neutrons (n) from background cosmic particles (muons) and neutron-induced gamma rays (γ). This paper describes a fast neutron flux analyzer with real-time digital pulse-shape discrimination (DPSD) algorithm FPGA-implemented for the GOL–3 and GDT devices. This analyzer was tested and calibrated with the help of {sup 137}Cs and {sup 252}Cf radiation sources. The Figures of Merit (FOM) calculated for different energy cuts are presented. - Highlights: • Electronic equipment for measurement of fast neutron flux with stilbene scintillator is presented. • FPGA-implemented digital pulse-shape discrimination algorithm by charge comparison method is shown. • Calibration of analyzer was carried out with {sup 137}Cs and {sup 252}Cf. • Figures of Merit (FOM) values for energy cuts from 1/8 Cs to 2 Cs are from 1.264 to 2.34 respectively.

  13. Comparison of model fitting and gated integration for pulse shape discrimination and spectral estimation of digitized lanthanum halide scintillator pulses

    Energy Technology Data Exchange (ETDEWEB)

    McFee, J.E., E-mail: jemcfee@telus.net; Mosquera, C.M.; Faust, A.A.

    2016-08-21

    An analysis of digitized pulse waveforms from experiments with LaBr{sub 3}(Ce) and LaCl{sub 3}(Ce) detectors is presented. Pulse waveforms from both scintillator types were captured in the presence of {sup 22}Na and {sup 60}Co sources and also background alone. Two methods to extract pulse shape discrimination (PSD) parameters and estimate energy spectra were compared. The first involved least squares fitting of the pulse waveforms to a physics-based model of one or two exponentially modified Gaussian functions. The second was the conventional gated integration method. The model fitting method produced better PSD than gated integration for LaCl{sub 3}(Ce) and higher resolution energy spectra for both scintillator types. A disadvantage to the model fitting approach is that it is more computationally complex and about 5 times slower. LaBr{sub 3}(Ce) waveforms had a single decay component and showed no ability for alpha/electron PSD. LaCl{sub 3}(Ce) was observed to have short and long decay components and alpha/electron discrimination was observed.

  14. Fast-Neutron Spectrometry Using a 3He Ionization Chamber and Digital Pulse Shape Analysis

    Energy Technology Data Exchange (ETDEWEB)

    D. L. Chichester; J. T. Johnson; E. H. Seabury

    2010-05-01

    Digital pulse shape analysis (dPSA) has been used with a Cuttler-Shalev type 3He proportional counter to measure the fast neutron spectra of bare 252Cf and 241AmBe neutron sources. Measurements have also been made to determine the attenuated fast neutron spectra of 252Cf shielded by several materials including water, graphite, liquid nitrogen, magnesium, and tungsten. Rise-time dPSA has been employed using the common rise-time approach for analyzing n +3He ? 1H + 3H ionization events and a new approach has been developed to improve the fidelity of these measurements. Simulations have been performed for the different experimental arrangements and are compared, demonstrating general agreement between the dPSA processed fast neutron spectra and predictions.

  15. A real-time n/γ digital pulse shape discriminator based on FPGA.

    Science.gov (United States)

    Li, Shiping; Xu, Xiufeng; Cao, Hongrui; Yuan, Guoliang; Yang, Qingwei; Yin, Zejie

    2013-02-01

    A FPGA-based real-time digital pulse shape discriminator has been employed to distinguish between neutrons (n) and gammas (γ) in the Neutron Flux Monitor (NFM) for International Thermonuclear Experimental Reactor (ITER). The discriminator takes advantages of the Field Programmable Gate Array (FPGA) parallel and pipeline process capabilities to carry out the real-time sifting of neutrons in n/γ mixed radiation fields, and uses the rise time and amplitude inspection techniques simultaneously as the discrimination algorithm to observe good n/γ separation. Some experimental results have been presented which show that this discriminator can realize the anticipated goals of NFM perfectly with its excellent discrimination quality and zero dead time.

  16. Application of neural networks to digital pulse shape analysis for an array of silicon strip detectors

    Energy Technology Data Exchange (ETDEWEB)

    Flores, J.L. [Dpto de Ingeniería Eléctrica y Térmica, Universidad de Huelva (Spain); Martel, I. [Dpto de Física Aplicada, Universidad de Huelva (Spain); CERN, ISOLDE, CH 1211 Geneva, 23 (Switzerland); Jiménez, R. [Dpto de Ingeniería Electrónica, Sist. Informáticos y Automática, Universidad de Huelva (Spain); Galán, J., E-mail: jgalan@diesia.uhu.es [Dpto de Ingeniería Electrónica, Sist. Informáticos y Automática, Universidad de Huelva (Spain); Salmerón, P. [Dpto de Ingeniería Eléctrica y Térmica, Universidad de Huelva (Spain)

    2016-09-11

    The new generation of nuclear physics detectors that used to study nuclear reactions is considering the use of digital pulse shape analysis techniques (DPSA) to obtain the (A,Z) values of the reaction products impinging in solid state detectors. This technique can be an important tool for selecting the relevant reaction channels at the HYDE (HYbrid DEtector ball array) silicon array foreseen for the Low Energy Branch of the FAIR facility (Darmstadt, Germany). In this work we study the feasibility of using artificial neural networks (ANNs) for particle identification with silicon detectors. Multilayer Perceptron networks were trained and tested with recent experimental data, showing excellent identification capabilities with signals of several isotopes ranging from {sup 12}C up to {sup 84}Kr, yielding higher discrimination rates than any other previously reported.

  17. Application of neural networks to digital pulse shape analysis for an array of silicon strip detectors

    Science.gov (United States)

    Flores, J. L.; Martel, I.; Jiménez, R.; Galán, J.; Salmerón, P.

    2016-09-01

    The new generation of nuclear physics detectors that used to study nuclear reactions is considering the use of digital pulse shape analysis techniques (DPSA) to obtain the (A,Z) values of the reaction products impinging in solid state detectors. This technique can be an important tool for selecting the relevant reaction channels at the HYDE (HYbrid DEtector ball array) silicon array foreseen for the Low Energy Branch of the FAIR facility (Darmstadt, Germany). In this work we study the feasibility of using artificial neural networks (ANNs) for particle identification with silicon detectors. Multilayer Perceptron networks were trained and tested with recent experimental data, showing excellent identification capabilities with signals of several isotopes ranging from 12C up to 84Kr, yielding higher discrimination rates than any other previously reported.

  18. Fast neutron flux analyzer with real-time digital pulse shape discrimination

    Science.gov (United States)

    Ivanova, A. A.; Zubarev, P. V.; Ivanenko, S. V.; Khilchenko, A. D.; Kotelnikov, A. I.; Polosatkin, S. V.; Puryga, E. A.; Shvyrev, V. G.; Sulyaev, Yu. S.

    2016-08-01

    Investigation of subthermonuclear plasma confinement and heating in magnetic fusion devices such as GOL-3 and GDT at the Budker Institute (Novosibirsk, Russia) requires sophisticated equipment for neutron-, gamma- diagnostics and upgrading data acquisition systems with online data processing. Measurement of fast neutron flux with stilbene scintillation detectors raised the problem of discrimination of the neutrons (n) from background cosmic particles (muons) and neutron-induced gamma rays (γ). This paper describes a fast neutron flux analyzer with real-time digital pulse-shape discrimination (DPSD) algorithm FPGA-implemented for the GOL-3 and GDT devices. This analyzer was tested and calibrated with the help of 137Cs and 252Cf radiation sources. The Figures of Merit (FOM) calculated for different energy cuts are presented.

  19. Pulse-shape discrimination of the new plastic scintillators in neutron-gamma mixed field using fast digitizer card

    Science.gov (United States)

    Jančář, A.; Kopecký, Z.; Dressler, J.; Veškrna, M.; Matěj, Z.; Granja, C.; Solar, M.

    2015-11-01

    Recently invented plastic scintillator EJ-299-33 enables pulse-shape discrimination (PSD) and thus measurement of neutron and photon spectra in mixed fields. In this work we compare the PSD properties of EJ-299-33 plastic and the well-known NE-213 liquid scintillator in monoenergetic neutron fields generated by the Van de Graaff accelerator using the 3H(d, n)4He reaction. Pulses from the scintillators are processed by a newly developed digital measuring system employing the fast digitizer card. This card contains two AD converters connected to the measuring computer via 10 Gbps optical ethernet. The converters operate with a resolution of 12 bits and have two differential inputs with a sampling frequency 1 GHz. The resulting digital channels with different gains are merged into one composite channel with a higher digital resolution in a wide dynamic range of energies. Neutron signals are fully discriminated from gamma signals. Results are presented.

  20. Fast-neutron spectrometry using a ³He ionization chamber and digital pulse shape analysis.

    Science.gov (United States)

    Chichester, D L; Johnson, J T; Seabury, E H

    2012-08-01

    Digital pulse shape analysis (dPSA) has been used with a Cuttler-Shalev type (3)He ionization chamber to measure the fast-neutron spectra of a deuterium-deuterium electronic neutron generator, a bare (252)Cf spontaneous fission neutron source, and of the transmitted fast neutron spectra of a (252)Cf source attenuated by water, graphite, liquid nitrogen, and magnesium. Rise-time dPSA has been employed using the common approach for analyzing n +(3)He→(1)H+(3)H ionization events and improved to account for wall-effect and pile-up events, increasing the fidelity of these measurements. Simulations have been performed of the different experimental arrangements and compared with the measurements, demonstrating general agreement between the dPSA-processed fast-neutron spectra and predictions. The fast-neutron resonance features of the attenuation cross sections of the attenuating materials are clearly visible within the resolution limits of the electronics used for the measurements, and the potential applications of high-resolution fast-neutron spectrometry for nuclear nonproliferation and safeguards measurements are discussed.

  1. New digital techniques applied to A and Z identification using pulse shape discrimination of silicon detector current signals

    Energy Technology Data Exchange (ETDEWEB)

    Barlini, S. [LPC Caen, ENSICAEN, University of Caen, CNRS/IN2P3, Caen (France)], E-mail: barlini@fi.infn.it; Bougault, R.; Laborie, Ph.; Lopez, O.; Mercier, D. [LPC Caen, ENSICAEN, University of Caen, CNRS/IN2P3, Caen (France); Parlog, M. [LPC Caen, ENSICAEN, University of Caen, CNRS/IN2P3, Caen (France); NIPNE, RO-76900 Bucharest (Romania); Tamain, B.; Vient, E. [LPC Caen, ENSICAEN, University of Caen, CNRS/IN2P3, Caen (France); Chevallier, E.; Chbihi, A.; Jacquot, B. [GANIL, CEA/DSM-CNRS/IN2P3, Caen (France); Kravchuk, V.L. [INFN-LNL, I-35020 Legnaro, Padova (Italy)

    2009-03-11

    Extending pulse shape discrimination (PSD) to digitized signals is one of the most promising methods to identify particles stopped in a detector. Using the CIME accelerator in the GANIL laboratory, a measurement campaign was done to collect data corresponding to different charges, masses and energies of implanted ions. These data are used to develop an algorithm capable to discriminate the different particles both in mass and charge. In this experiment, a 300{mu}m n-TD reverse mounted Si detector was used. These studies on PSD are part of the FAZIA R and D, a research and development project aiming at building a new 4{pi} array for isospin nuclear physics.

  2. Neutron-Gamma Pulse Shape Discrimination with a NE-213 Liquid Scintillator by Using Digital Signal Processing Combined with Similarity Method

    Directory of Open Access Journals (Sweden)

    Mardiyanto

    2008-07-01

    Full Text Available Neutron-Gamma Pulse Shape Discrimination with a NE-213 Liquid Scintillator by Using Digital Signal Processing Combined with Similarity Method. Measurement of mixed neutron-gamma radiation is difficult because a neuclear detector is usually sensitive to both radiations. A new attempt of neutron-gamma pulse shape discrimination for a NE-213 liquid scintillator is presented by using digital signal processing combined with an off-line similarity method. The output pulse shapes are digitized with a high speed digital oscilloscope. The n-γ discrimination is done by calculating the index of each pulse shape, which is determined by the similarity method, and then fusing it with its corresponding pulse height. Preliminary results demonstrate good separation of neutron and gamma-ray signals from a NE-213 scintillator with a simple digital system. The results were better than those with a conventional rise time method. Figure of Merit is used to determine the quality of discrimination. The figure of merit of the discrimination using digital signal processing combined with of line similarity method are 1.9; 1.7; 1.1; 1.1; and 0.8 ; on the other hand by using conventional method the rise time are 0.9; 0.9; 0.9; 0.7; and 0.4 for the equivalent electron energy of 800 ; 278 ; 139 ; 69 ; and 30 keV

  3. Study of digital pulse shape discrimination method for n-{\\gamma} separation of EJ-301 liquid scintillation detector

    CERN Document Server

    Wan, Bo; Chen, Liang; Ge, Honglin; Ma, Fei; Zhang, Hongbin; Ju, Yongqin; Zhang, Yanbin; Li, Yanyan; Xu, Xiaowei

    2015-01-01

    A digital pulse shape discrimination system based on a programmable module NI-5772 has been established and tested with EJ-301 liquid scintillation detector. The module was operated by means of running programs developed in LabVIEW with the sampling frequency up to 1.6GS/s. Standard gamma sources 22Na, 137Cs and 60Co were used to calibrate the EJ-301 liquid scintillation detector, and the gamma response function has been obtained. Digital algorithms for charge comparison method and zero-crossing method have been developed. The experimental results showed that both digital signal processing (DSP) algorithms could discriminate neutrons from gamma-rays. Moreover, the zero-crossing method shows better n-{\\gamma} discrimination at 80 keVee and lower, whereas the charge comparison method gives better results at higher thresholds. In addition, the figure-of-merit (FOM) of two different dimension detectors were extracted at 9 energy thresholds, and it was found that the smaller one presented a better n-{\\gamma} separ...

  4. Coincidence measurements in {alpha}/{beta}/{gamma} spectrometry with phoswich detectors using digital pulse shape discrimination analysis

    Energy Technology Data Exchange (ETDEWEB)

    Celis, B. de [University of Leon, Escuela de Ingenieria Industrial, Leon 24071 (Spain)], E-mail: bcelc@unileon.es; Fuente, R. de la [University of Leon, Escuela de Ingenieria Industrial, Leon 24071 (Spain); Williart, A. [UNED, F. Ciencias Fisicas, Madrid 28040 (Spain); Celis Alonso, B. de [King' s College London, IoP, De Crespigny Park, London SE5 8AF (United Kingdom)

    2007-09-21

    A novel system has been developed for the detection of low radioactivity levels using coincidence techniques. The device combines a phoswich detector for {alpha}/{beta}/{gamma} ray recognition with a fast digital card for electronic pulse analysis. The detector is able to discriminate different types of radiation in a mixed {alpha}/{beta}/{gamma} field and can be used in a coincidence mode by identifying the composite signal produced by the simultaneous detection of {beta} particles in a plastic scintillator and {gamma} rays in an NaI(Tl) scintillator. Use of a coincidence technique with phoswich detectors was proposed recently to verify the Nuclear Test Ban Treaty, which made it necessary to monitor the low levels of xenon radioisotopes produced by underground nuclear explosions. Previous studies have shown that combining CaF{sub 2}(Eu) for {beta} ray detection and NaI(Tl) for {gamma} ray detection makes it difficult to identify the coincidence signals because of the similar fluorescence decay times of the two scintillators. With the device proposed here, it is possible to identify the coincidence events owing to the short fluorescence decay time of the plastic scintillator. The sensitivity of the detector may be improved by employing liquid scintillators, which allow low radioactivity levels from actinides to be measured when present in environmental samples. The device developed is simpler to use than conventional coincidence equipment because it uses a single detector and electronic circuit, and it offers fast and precise analysis of the coincidence signals by employing digital pulse shape analysis.

  5. Pulse shaping using a spatial light modulator

    CSIR Research Space (South Africa)

    Botha, N

    2009-07-01

    Full Text Available Femtosecond pulse shaping can be done by different kinds of pulse shapers, such as liquid crystal spatial light modulators (LC SLM), acousto optic modulators (AOM) and deformable and movable mirrors. A few applications where pulse shaping...

  6. Implementation of a neural network for digital pulse shape analysis on a FPGA for on-line identification of heavy ions

    Science.gov (United States)

    Jiménez, R.; Sánchez-Raya, M.; Gómez-Galán, J. A.; Flores, J. L.; Dueñas, J. A.; Martel, I.

    2012-05-01

    Pulse shape analysis techniques for the identification of heavy ions produced in nuclear reactions have been recently proposed as an alternative to energy loss and time of flight methods. However this technique requires a large amount of memory for storing the shapes of charge and current signals. We have implemented a hardware solution for fast on-line processing of the signals producing the relevant information needed for particle identification. Since the pulse shape analysis can be formulated in terms of a pattern recognition problem, a neural network has been implemented in a FPGA device. The design concept has been tested using 12,13C ions produced in heavy ion reactions. The actual latency of the system is about 20 μs when using a clock frequency of 50 MHz.

  7. Implementation of a neural network for digital pulse shape analysis on a FPGA for on-line identification of heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, R., E-mail: naharro@uhu.es [Departamento de Ingenieria Eletronica, Sistemas Informaticos y Automatica, Universidad de Huelva, 21071 Huelva (Spain); Sanchez-Raya, M.; Gomez-Galan, J.A. [Departamento de Ingenieria Eletronica, Sistemas Informaticos y Automatica, Universidad de Huelva, 21071 Huelva (Spain); Flores, J.L. [Departamento Ingenieria Electrica y Termica, Universidad de Huelva, 21071 Huelva (Spain); Duenas, J.A.; Martel, I. [Departamento de Fisica Aplicada, Universidad de Huelva, 21071 Huelva (Spain)

    2012-05-11

    Pulse shape analysis techniques for the identification of heavy ions produced in nuclear reactions have been recently proposed as an alternative to energy loss and time of flight methods. However this technique requires a large amount of memory for storing the shapes of charge and current signals. We have implemented a hardware solution for fast on-line processing of the signals producing the relevant information needed for particle identification. Since the pulse shape analysis can be formulated in terms of a pattern recognition problem, a neural network has been implemented in a FPGA device. The design concept has been tested using {sup 12,13}C ions produced in heavy ion reactions. The actual latency of the system is about 20 {mu}s when using a clock frequency of 50 MHz.

  8. Analysis of Beaulieu Pulse Shaping Family Based FIR Filter for WCDMA

    CERN Document Server

    Kang, A S

    2010-01-01

    The analysis and simulation of transmit and receive pulse shaping filter is an important aspect of digital wireless communication since it has a direct effect on error probabilities. Pulse shaping for wireless communication over time as well as frequency selective channels is the need of hour for 3G and 4G systems. The pulse shaping filter is a useful means to shape the signal spectrum and avoid interferences. Basically digital filters are used to modify the characteristics of signal in time and frequency domain and have been recognized as primary digital signal processing operations.

  9. High-speed pulse-shape generator, pulse multiplexer

    Science.gov (United States)

    Burkhart, Scott C.

    2002-01-01

    The invention combines arbitrary amplitude high-speed pulses for precision pulse shaping for the National Ignition Facility (NIF). The circuitry combines arbitrary height pulses which are generated by replicating scaled versions of a trigger pulse and summing them delayed in time on a pulse line. The combined electrical pulses are connected to an electro-optic modulator which modulates a laser beam. The circuit can also be adapted to combine multiple channels of high speed data into a single train of electrical pulses which generates the optical pulses for very high speed optical communication. The invention has application in laser pulse shaping for inertial confinement fusion, in optical data links for computers, telecommunications, and in laser pulse shaping for atomic excitation studies. The invention can be used to effect at least a 10.times. increase in all fiber communication lines. It allows a greatly increased data transfer rate between high-performance computers. The invention is inexpensive enough to bring high-speed video and data services to homes through a super modem.

  10. Pulse-shaping strategies in short-pulse fiber amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Schimpf, Damian Nikolaus

    2010-02-09

    Ultrashort pulse lasers are an important tool in scientific and industrial applications. However, many applications are demanding higher average powers from these ultrashort pulse sources. This can be achieved by combining direct diode pumping with novel gain media designs. In particular, ultrashort pulse fiber lasers are now delivering average powers in the kW range. However, the design of fiber lasers, producing pulses with high peak-powers, is challenging due to the impact of nonlinear effects. To significantly reduce these detrimental effects in ultrashort pulse fiber amplifers, the combination of chirped pulse amplification (CPA) and large mode area fibers is employed. Using these methods, the pulse energy of fiber lasers has been steadily increasing for the past few years. Recently, a fiber-based CPA-system has been demonstrated which produces pulse energies of around 1 mJ. However, both the stretching and the enlargement of the mode area are limited, and therefore, the impact of nonlinearity is still noticed in systems employing such devices. The aim of this thesis is the analysis of CPA-systems operated beyond the conventional nonlinear limit, which corresponds to accumulated nonlinear phase-shifts around 1 rad. This includes a detailed discussion of the influence of the nonlinear effect self-phase modulation on the output pulse of CPA-systems. An analytical model is presented. Emphasis is placed on the design of novel concepts to control the impact of self-phase modulation. Pulse-shaping is regarded as a powerful tool to accomplish this goal. Novel methods to control the impact of SPM are experimentally demonstrated. The design of these concepts is based on the theoretical findings. Both amplitude- and phase-shaping are studied. Model-based phase-shaping is implemented in a state-of-the-art fiber CPA-system. The influence of the polarization state is also highlighted. Additionally, existing techniques and recent advances are put into context. (orig.)

  11. Multiple-beam pulse shaping and preamplification

    Energy Technology Data Exchange (ETDEWEB)

    Wilcox, R.B.; VanWonterghem, B.W.; Burkhart, S.C.; Davin, J.M.

    1994-11-09

    Glass fusion laser systems typically use a master oscillator-power amplifier (MOPA) architecture, where control of the optical pulse temporal and spatial parameters is accomplished mainly in the master oscillator and low power optics. The pulses from this low power ``front end`` are amplified in the power amplifier, which modifies the pulse shape temporally and spatially. Nonlinear frequency conversion crystals following the amplifier further change the pulse before it reaches the target. To effectively control the optical pulse on target for different types of experiments, and compensate for nonlinearity in the preceding optics, the front end system must be versatile enough to easily control many pulse parameters over a large range. The front end pulse generation system described in this article represents a new approach to this problem. The proposed National Ignition Facility (NIF) has 192 beamlines, each of which requires an input pulse of up to 12 Joules in around 4 ns equivalent square pulse length. Considerations of laser architecture for supplying each of these beamlines from a central oscillator system were crucial in the design of the front end. Previous lasers have used bulk optics to split a single oscillator signal and report beams to multiple amplifier chains. A key idea in the current design is to replace bulk optic transport with fibers, eliminating large opto-mechanical subsystems. Another important concept is convenient pulse forming using low voltage integrated optic modulators. The integrated optic and fiber optic concepts resulted in the current pulse generation designs for NEF. An important advantage is that each of the beamlines can have an independently controlled temporal pulse shape, which provides for precise balance of instantaneous power on target.

  12. Laser pulse shaping for high gradient accelerators

    Science.gov (United States)

    Villa, F.; Anania, M. P.; Bellaveglia, M.; Bisesto, F.; Chiadroni, E.; Cianchi, A.; Curcio, A.; Galletti, M.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Gatti, G.; Moreno, M.; Petrarca, M.; Pompili, R.; Vaccarezza, C.

    2016-09-01

    In many high gradient accelerator schemes, i.e. with plasma or dielectric wakefield induced by particles, many electron pulses are required to drive the acceleration of one of them. Those electron bunches, that generally should have very short duration and low emittance, can be generated in photoinjectors driven by a train of laser pulses coming inside the same RF bucket. We present the system used to shape and characterize the laser pulses used in multibunch operations at Sparc_lab. Our system gives us control over the main parameter useful to produce a train of up to five high brightness bunches with tailored intensity and time distribution.

  13. Laser pulse shaping for high gradient accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Villa, F., E-mail: fabio.villa@lnf.infn.it [INFN-Laboratori Nazionali di Frascati, via E. Fermi 40, 00044 Frascati (Italy); Anania, M.P.; Bellaveglia, M. [INFN-Laboratori Nazionali di Frascati, via E. Fermi 40, 00044 Frascati (Italy); Bisesto, F. [INFN-Laboratori Nazionali di Frascati, via E. Fermi 40, 00044 Frascati (Italy); Università La Sapienza di Roma, Via A. Scarpa 14, Rome (Italy); Chiadroni, E. [INFN-Laboratori Nazionali di Frascati, via E. Fermi 40, 00044 Frascati (Italy); Cianchi, A. [INFN-Roma Tor Vergata and Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome (Italy); Curcio, A.; Galletti, M.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Gatti, G. [INFN-Laboratori Nazionali di Frascati, via E. Fermi 40, 00044 Frascati (Italy); Moreno, M.; Petrarca, M. [Università La Sapienza di Roma, Via A. Scarpa 14, Rome (Italy); Pompili, R.; Vaccarezza, C. [INFN-Laboratori Nazionali di Frascati, via E. Fermi 40, 00044 Frascati (Italy)

    2016-09-01

    In many high gradient accelerator schemes, i.e. with plasma or dielectric wakefield induced by particles, many electron pulses are required to drive the acceleration of one of them. Those electron bunches, that generally should have very short duration and low emittance, can be generated in photoinjectors driven by a train of laser pulses coming inside the same RF bucket. We present the system used to shape and characterize the laser pulses used in multibunch operations at Sparc-lab. Our system gives us control over the main parameter useful to produce a train of up to five high brightness bunches with tailored intensity and time distribution.

  14. Shaping metallic glasses by electromagnetic pulsing

    Science.gov (United States)

    Kaltenboeck, Georg; Demetriou, Marios D.; Roberts, Scott; Johnson, William L.

    2016-01-01

    With damage tolerance rivalling advanced engineering alloys and thermoplastic forming capabilities analogous to conventional plastics, metallic glasses are emerging as a modern engineering material. Here, we take advantage of their unique electrical and rheological properties along with the classic Lorentz force concept to demonstrate that electromagnetic coupling of electric current and a magnetic field can thermoplastically shape a metallic glass without conventional heating sources or applied mechanical forces. Specifically, we identify a process window where application of an electric current pulse in the presence of a normally directed magnetic field can ohmically heat a metallic glass to a softened state, while simultaneously inducing a large enough magnetic body force to plastically shape it. The heating and shaping is performed on millisecond timescales, effectively bypassing crystallization producing fully amorphous-shaped parts. This electromagnetic forming approach lays the groundwork for a versatile, time- and energy-efficient manufacturing platform for ultrastrong metals. PMID:26853460

  15. Shaping metallic glasses by electromagnetic pulsing

    Science.gov (United States)

    Kaltenboeck, Georg; Demetriou, Marios D.; Roberts, Scott; Johnson, William L.

    2016-02-01

    With damage tolerance rivalling advanced engineering alloys and thermoplastic forming capabilities analogous to conventional plastics, metallic glasses are emerging as a modern engineering material. Here, we take advantage of their unique electrical and rheological properties along with the classic Lorentz force concept to demonstrate that electromagnetic coupling of electric current and a magnetic field can thermoplastically shape a metallic glass without conventional heating sources or applied mechanical forces. Specifically, we identify a process window where application of an electric current pulse in the presence of a normally directed magnetic field can ohmically heat a metallic glass to a softened state, while simultaneously inducing a large enough magnetic body force to plastically shape it. The heating and shaping is performed on millisecond timescales, effectively bypassing crystallization producing fully amorphous-shaped parts. This electromagnetic forming approach lays the groundwork for a versatile, time- and energy-efficient manufacturing platform for ultrastrong metals.

  16. Applications of digital pulse processing in nuclear spectroscopy

    CERN Document Server

    Grzywacz, R

    2003-01-01

    Data acquisition systems for nuclear spectroscopy have traditionally been based on hybrid systems with analog shaping amplifiers followed by analog-to-digital converters. Recently, however, new systems based on digital signal processing concepts have been developed. For example, one specific design, the Digital Gamma Finder (DGF-4C), has been used extensively for particle- and gamma-spectroscopy of nuclei far from stability. Using the DGF-4C, a variety of data acquisition systems have been implemented and used for measurements with semiconductor and scintillator detectors at recoil separators like the RMS at ORNL, the FRS at GSI and LISE at GANIL. Some novel features and unique advantages, such as trigger-less operation and pulse shape recording, are discussed in the context of selected studies.

  17. Drop shaping by laser-pulse impact

    CERN Document Server

    Klein, Alexander L; Visser, Claas Willem; Lhuissier, Henri; Sun, Chao; Snoeijer, Jacco H; Villermaux, Emmanuel; Lohse, Detlef; Gelderblom, Hanneke

    2015-01-01

    We study the hydrodynamic response of a falling drop hit by a laser pulse. Combining high-speed with stroboscopic imaging we report that a millimeter-sized dyed water drop hit by a milli-Joule nanosecond laser-pulse deforms and propels forward at several meters per second, until it eventually fragments. We show that the drop motion results from the recoil momentum imparted at the drop surface by water vaporization. We measure the propulsion speed and the time-deformation law of the drop, complemented by boundary integral simulations. We explain the drop propulsion and shaping in terms of the laser pulse energy and drop surface tension. These findings are crucial for the generation of extreme ultraviolet (EUV) light in lithography machines.

  18. Triangle bipolar pulse shaping and pileup correction based on DSP

    Energy Technology Data Exchange (ETDEWEB)

    Esmaeili-sani, Vahid, E-mail: vaheed_esmaeely80@yahoo.com [Department of Nuclear Engineering and Physics, Amirkabir University of Technology, P.O. Box 4155-4494, Tehran (Iran, Islamic Republic of); Moussavi-zarandi, Ali; Akbar-ashrafi, Nafiseh; Boghrati, Behzad [Department of Nuclear Engineering and Physics, Amirkabir University of Technology, P.O. Box 4155-4494, Tehran (Iran, Islamic Republic of)

    2011-02-11

    Programmable Digital Signal Processing (DSP) microprocessors are capable of doing complex discrete signal processing algorithms with clock rates above 50 MHz. This combined with their low expense, ease of use and selected dedicated hardware make them an ideal option for spectrometer data acquisition systems. For this generation of spectrometers, functions that are typically performed in dedicated circuits, or offline, are being migrated to the field programmable gate array (FPGA). This will not only reduce the electronics, but the features of modern FPGAs can be utilized to add considerable signal processing power to produce higher resolution spectra. In this paper we report on an all-digital triangle bipolar pulse shaping and pileup correction algorithm that is being developed for the DSP. The pileup mitigation algorithm will allow the spectrometers to run at higher count rates or with multiple sources without imposing large data losses due to the overlapping of scintillation signals. This correction technique utilizes a very narrow bipolar triangle digital pulse shaping algorithm to extract energy information for most pileup events.

  19. Digital Modeling and Shaping of Design Practices

    DEFF Research Database (Denmark)

    Reijonen, Satu

    This paper focuses on the role of digital modeling in shaping coordinative practices between architects and energy engineers in construction design. The paper presents a case study of the use of an energy performance calculation programme, a numeric digital modeling tool, that not only enables......, 2010), and the socio-material constructivist studies of technology (Akrich 1992, Akrich et al. 2000, Latour 1991). The programme influences the coordinative practices in following ways: it shapes the modus of interaction between energy engineers and architects and enforces particular jurisdictional...... of this study suggest that generative potential of digital modeling tools such as the calculation programme resides in their ability to restrictively define the possible roles in, focus of and sequence of working. In addition, digital modeling provides a separate medium with the help of which the design object...

  20. Single-cycle optical pulse shaping

    Science.gov (United States)

    Shverdin, Miroslav Y.

    Observation and control of ultrafast processes such as chemical reactions, biological interactions, and atomic processes is at the heart of the field of ultrafast physics. Decreasing the pulse duration enables probing ever-shorter events. The main contribution of this work is the generation and the characterization of single-cycle optical pulses. When the shape of the electric field consists of a single oscillation under the temporal envelope, we approach a new regime in physics: the electronic motion is now controlled directly by the electric field. We describe a Fourier approach to ultrashort pulse generation which consists of combining discrete, appropriately phased spectral components of a very wide coherent spectrum. In our experiments, all of the sidebands are generated by exciting a Raman transition in a diatomic gas near maximum coherence using two intense pulsed lasers. The resulting molecular motion modulates the two driving lasers to produce over four octaves of bandwidth from vacuum ultraviolet to near infrared. The spectral components are mutually coherent and are spaced by the frequency of the Raman transition. We select a subset of the produced spectrum and electronically adjust the phases of the individual sidebands using a liquid crystal spatial light modulator. The synthesized waveforms are characterized by measuring the UV signal generated by four-wave nonresonant mixing inside a xenon cell.

  1. Encoded Dynamical Recoupling with Shaped Pulses

    Science.gov (United States)

    Li, Yunfan; Lidar, Daniel A.; Pryadko, Leonid P.

    2008-03-01

    Encoded Dynamical Recoupling is a passive error correction techique which can be used to enhance the performance of a quantum error correction code (QECC) against low-frequency component of the thermal bath. The elements of the stabilizer group are used in the decoupling cycle which makes the encoded logic operations fault-tolerant. We studied the effectiveness of this techique both analytically and numerically for several three- and five-qubit codes, with decoupling sequences utilizing either Gaussian or self-refocusing pulse shapes. When logic pulses are intercalated between the decoupling cycles, the technique may be very effective in cancelling constant perturbation terms, but its performance is much weaker against a time-dependent perturbation simulated as a classical correlated noise. The decoupling accuracy can be substantially improved if logic is applied slowly and concurrently with the decoupling, so that a certain adiabaticity condition is satisfied.

  2. Pulse Shape Discrimination in the IGEX Experiment

    CERN Document Server

    González, D; Cebrián, S; García, E; Irastorza, I G; Morales, A; De Solorzano, A O; Puimedón, J; Sarsa, M L; Villar, J A; Aalseth, C E; Brodzinski, R L; Hensley, W K; Miley, H S; Reeves, J H; Kirpichnikov, I V; Klimenko, A A; Osetrov, S B; Smolnikov, A A; Vasenko, A A; Vasilev, S I; Pogosov, V S; Tamanyan, A G

    2003-01-01

    The IGEX experiment has been operating enriched germanium detectors in the Canfranc Underground Laboratory (Spain) in a search for the neutrinoless double decay of 76Ge. The implementation of Pulse Shape Discrimination techniques to reduce the radioactive background is described in detail. This analysis has been applied to a fraction of the IGEX data, leading to a rejection of ~60 % of their background, in the region of interest (from 2 to 2.5 MeV), down to ~0.09 c/(keV kg y).

  3. Evolution of laser pulse shape in a parabolic plasma channel

    Science.gov (United States)

    Kaur, M.; Gupta, D. N.; Suk, H.

    2017-01-01

    During high-intensity laser propagation in a plasma, the group velocity of a laser pulse is subjected to change with the laser intensity due to alteration in refractive index associated with the variation of the nonlinear plasma density. The pulse front sharpened while the back of the pulse broadened due to difference in the group velocity at different parts of the laser pulse. Thus the distortion in the shape of the laser pulse is expected. We present 2D particle-in-cell simulations demonstrating the controlling the shape distortion of a Gaussian laser pulse using a parabolic plasma channel. We show the results of the intensity distribution of laser pulse in a plasma with and without a plasma channel. It has been observed that the plasma channel helps in controlling the laser pulse shape distortion. The understanding of evolution of laser pulse shape may be crucial while applying the parabolic plasma channel for guiding the laser pulse in plasma based accelerators.

  4. Enhancement of Time-Reversal Subwavelength Wireless Transmission Using Pulse Shaping

    CERN Document Server

    Ding, Shuai; Zou, Lianfeng; Wang, Bingzhong; Caloz, Christophe

    2014-01-01

    A novel time-reversal subwavelength transmission technique, based on pulse shaping circuits (PSCs), is proposed. Compared to previously reported approaches, this technique removes the need for complex or electrically large electromagnetic structures by generating channel diversity via pulse shaping instead of angular spectrum transformation. Moreover, the pulse shaping circuits (PSCs) are based on Radio Analog Signal Processing (R-ASP), and therefore do not suffer from the well-known issues of digital signal processing in ultrafast regimes. The proposed PSC time-reversal systems is mathematically shown to offer high channel discrimination under appropriate PSC design conditions, and is experimentally demonstrated for the case of two receivers.

  5. ICI Alleviation in OFDM System Utilizing Scale Alpha Pulse Shaping

    Directory of Open Access Journals (Sweden)

    Nor Adibah Ibrahim

    2015-05-01

    Full Text Available In this study, a new pulse shaping method namely scale alpha is proposed for mitigating Inter-Carrier Interference (ICI effect in Orthogonal Frequency-Division Multiplexing (OFDM system. The suggested pulse shape is designed and simulated using MATLAB software. Results show that the new pulse shape has lower ICI power and better impulse response performance than Franks, raised cosine and double-jump pulses.

  6. Pulse-Shape Discrimination for Low-Background Proportional Counting

    Science.gov (United States)

    Aalseth, Craig

    2011-10-01

    Digital pulse-shape discrimination (PSD) is used to improve measurement sensitivity for internal-source gas proportional counters. Because the design of these detectors can be physically simple, they are well-suited for low-background applications where the radiopurity of detector materials must be stringently controlled. After mitigating dominant backgrounds (cosmic rays, external gamma-rays, radioactivity in materials), remaining background events frequently do not arise from ionization of the proportional counter gas. Various PSD methods have exploited the resulting pulse-shape differences. More sophisticated methods can offer better discrimination but may lead to more difficult calibration between model and detector. Variations between modeled and experimental shapes can limit the discriminating power achieved. This work addresses this difficulty by generating a template shape from each individual sample measurement of interest, a ``self-calibrating'' template. Differences in event topology can also cause differences in pulse shape. In this work the temporal region analyzed is limited to maximize background discrimination while avoiding unwanted sensitivity to event topology. Low-background measurements of tritium, carbon-14, argon-37, and argon-39 are currently being developed at the Pacific Northwest National Laboratory with detectors employing radiopure materials developed for neutrinoless double-beta decay and dark matter searches. The application of self-calibrating template PSD to measurement of these radioisotopes, along with initial measurement results, is described. Applications such as nuclear treaty verification, elucidating the environmental carbon cycle, and the assay of low-background materials for next-generation nuclear physics experiments are presented.

  7. Photonuclear Contributions to SNS Pulse Shapes

    Energy Technology Data Exchange (ETDEWEB)

    McClanahan, Tucker C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Iverson, Erik B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gallmeier, Franz X. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-03-01

    cross sections available and the CEM03 physics model within MCNPX 2.6.0 in the simulation, we are able to estimate the impact of photoneutron production on both overall neutron production and delayed neutron production. We find that a significant number of photon-induced neutrons are produced a few milliseconds after the proton pulse, following prompt gamma emission through the capture of neutrons in the slowing-down and thermalization processes. We name these "slowing-down delayed neutrons" to distinguish them from either "activation-delayed neutrons" or "beta-delayed neutrons." The beta-delayed and activation-delayed neutrons were not part of this study, and will be addressed elsewhere. While these other delayed neutron channels result in the time-independent (constant) production of fast neutrons outside of the prompt pulse, the slowing-down delayed neutrons also a ect the shape of the pulses. Although numerically insignificant in most cases, we describe a set of scenarios related to T0-chopper operation in which the slowing-down delayed neutrons may be important.

  8. Ultrabroadband pulse shaping with a push-pull deformable mirror.

    Science.gov (United States)

    Bonora, Stefano; Brida, Daniele; Villoresi, Paolo; Cerullo, Giulio

    2010-10-25

    We report the programmable pulse shaping of ultrabroadband pulses by the use of a novel design of electrostatic deformable mirror based on push pull technology. We shape few-optical pulses from near-IR and visible optical parametric amplifiers, and demonstrate strong-field control of excited state population transfer in a dye molecule.

  9. Measuring the shape of randomly arriving pulses shorter than the acquisition step

    Science.gov (United States)

    Stoyanov, Dimitar V.; Dreischuh, Tanja N.; Vankov, Orlin I.; Gurdev, Ljuan L.

    2004-12-01

    In this paper we have developed and tested a novel method for measuring precisely the shape of pulses shorter than the acquisition step, which is effective for random delays of the input pulses with respect to the start pulse of the analogue-to-digital converter (ADC). The method is based on conversion of the short pulses to be measured into longer damped oscillations and their correct acquisition (sampling) with saving the pulse information, rearranging of the sampled oscillations with respect to some reference time instant to form a finer-discretization high-precision oscillation, and retrieving the pulse shape by inverse algorithms. We demonstrated experimentally the good performance (5-7% rms error) of this method (by using 20 MHz/8 bits ADC) when measuring the shape of randomly arriving pulses, shorter than the ADC sampling step (50 ns), with an equivalent sampling frequency up to 2 GHz (0.5 ns equivalent sampling step). The resolving of shapes in a pulse pair with an inter-pulse delay shorter than the ADC sampling interval has also been demonstrated. The limiting equivalent sampling frequency is estimated to be up to 500 GHz. This method can be effectively applied for creation of some novel short-pulse measuring techniques, avoiding the problem of time synchronization to the start pulses in lidar and radar, nuclear experiments, tomography, communications, etc.

  10. Tunable pulse-shaping with gated graphene nanoribbons

    DEFF Research Database (Denmark)

    Prokopeva, Ludmila; Emani, Naresh K.; Boltasseva, Alexandra

    2014-01-01

    We propose a pulse-shaper made of gated graphene nanoribbons. Simulations demonstrate tunable control over the shapes of transmitted and reflected pulses using the gating bias. Initial fabrication and characterization of graphene elements is also discussed.......We propose a pulse-shaper made of gated graphene nanoribbons. Simulations demonstrate tunable control over the shapes of transmitted and reflected pulses using the gating bias. Initial fabrication and characterization of graphene elements is also discussed....

  11. Tunable pulse-shaping with gated graphene nanoribbons

    DEFF Research Database (Denmark)

    Prokopeva, Ludmila; Emani, Naresh K.; Boltasseva, Alexandra

    2014-01-01

    We propose a pulse-shaper made of gated graphene nanoribbons. Simulations demonstrate tunable control over the shapes of transmitted and reflected pulses using the gating bias. Initial fabrication and characterization of graphene elements is also discussed.......We propose a pulse-shaper made of gated graphene nanoribbons. Simulations demonstrate tunable control over the shapes of transmitted and reflected pulses using the gating bias. Initial fabrication and characterization of graphene elements is also discussed....

  12. Laser pulse spectral shaping based on electro-optic modulation

    Institute of Scientific and Technical Information of China (English)

    Yanhai Wang; Jiangfeng Wang; You'en Jiang; Yan Bao; Xuechun Li; Zunqi Lin

    2008-01-01

    A new spectrum shaping method, based on electro-optic modulation, to alleviate gain narrowing in chirped pulse amplification (CPA) system, is described and numerically simulated. Near-Fourier transform-limited seed laser pulse is chirped linearly through optical stretcher. Then the chirped laser pulse is coupled into integrated waveguide electro-optic modulator driven by an aperture-coupled-stripline (ACSL) electricalwaveform generator, and the pulse shape and amplitude are shaped in time domain. Because of the directrelationship between frequency interval and time interval of the linearly chirped pulse, the laser pulse spectrum is shaped correspondingly. Spectrum-shaping examples are modeled numerically to determine the spectral resolution of this technique. The phase error introduced in this method is also discussed.

  13. Pulse-shape discrimination scintillators for homeland security applications

    Science.gov (United States)

    Ellis, Mark E.; Duroe, Kirk; Kendall, Paul A.

    2016-09-01

    An extensive programme of research has been conducted for scintillation liquids and plastics capable of neutron-gamma discrimination for deployment in future passive and active Homeland Security systems to provide protection against radiological and nuclear threats. The more established detection materials such as EJ-301 and EJ-309 are compared with novel materials such as EJ-299-33 and p-terphenyl. This research also explores the benefits that can be gained from improvements in the analogue-to-digital sampling rate and sample bit resolution. Results are presented on the Pulse Shape Discrimination performance of various detector and data acquisition combinations and how optimum configurations from these studies have been developed into field-ready detector arrays. Early results from application-specific experimental configurations of multi-element detector arrays are presented.

  14. A novel digital pulse processing architecture for nuclear instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Moline, Yoann; Thevenin, Mathieu; Corre, Gwenole [CEA, LIST - Laboratoire Capteurs et Architectures electroniques, F-91191 Gif-sur-Yvette, (France); Paindavoine, Michel [CNRS, Universite de Bourgogne - Laboratoire d' Etude de l' Apprentissage et du Developpement, 21000 DIJON, (France)

    2015-07-01

    The field of nuclear instrumentation covers a wide range of applications, including counting, spectrometry, pulse shape discrimination and multi-channel coincidence. These applications are the topic of many researches, new algorithms and implementations are constantly proposed thanks to advances in digital signal processing. However, these improvements are not yet implemented in instrumentation devices. This is especially true for neutron-gamma discrimination applications which traditionally use charge comparison method while literature proposes other algorithms based on frequency domain or wavelet theory which show better performances. Another example is pileups which are generally rejected while pileup correction algorithms also exist. These processes are traditionally performed offline due to two issues. The first is the Poissonian characteristic of the signal, composed of random arrival pulses which requires to current architectures to work in data flow. The second is the real-time requirement, which implies losing pulses when the pulse rate is too high. Despite the possibility of treating the pulses independently from each other, current architectures paralyze the acquisition of the signal during the processing of a pulse. This loss is called dead-time. These two issues have led current architectures to use dedicated solutions based on re-configurable components like Field Programmable Gate Arrays (FPGAs) to overcome the need of performance necessary to deal with dead-time. However, dedicated hardware algorithm implementations on re-configurable technologies are complex and time-consuming. For all these reasons, a programmable Digital pulse Processing (DPP) architecture in a high level language such as Cor C++ which can reduce dead-time would be worthwhile for nuclear instrumentation. This would reduce prototyping and test duration by reducing the level of hardware expertise to implement new algorithms. However, today's programmable solutions do not meet

  15. Dynamic parabolic pulse generation using temporal shaping of wavelength to time mapped pulses.

    Science.gov (United States)

    Nguyen, Dat; Piracha, Mohammad Umar; Mandridis, Dimitrios; Delfyett, Peter J

    2011-06-20

    Self-phase modulation in fiber amplifiers can significantly degrade the quality of compressed pulses in chirped pulse amplification systems. Parabolic pulses with linear frequency chirp are suitable for suppressing nonlinearities, and to achieve high peak power pulses after compression. In this paper, we present an active time domain technique to generate parabolic pulses for chirped pulse amplification applications. Pulses from a mode-locked laser are temporally stretched and launched into an amplitude modulator, where the drive voltage is designed using the spectral shape of the input pulse and the transfer function of the modulator, resulting in the generation of parabolic pulses. Experimental results of pulse shaping with a pulse train from a mode-locked laser are presented, with a residual error of less than 5%. Moreover, an extinction ratio of 27 dB is achieved, which is ideal for chirped pulse amplification applications.

  16. Cell shape identification using digital holographic microscopy

    CERN Document Server

    Zakrisson, Johan; Andersson, Magnus

    2015-01-01

    We present a cost-effective, simple and fast digital holographic microscopy method based upon Rayleigh-Sommerfeld back propagation for identification of the geometrical shape of a cell. The method was tested using synthetic hologram images generated by ray-tracing software and from experimental images of semi-transparent spherical beads and living red blood cells. Our results show that by only using the real part of the back-reconstructed amplitude the proposed method can provide information of the geometrical shape of the object and at the same time accurately determine the axial position of the object under study. The proposed method can be used in flow chamber assays for pathophysiological studies where fast morphological changes of cells are studied in high numbers and at different heights.

  17. Temporal resolution beyond the average pulse duration in shaped noisy-pulse transient absorption spectroscopy.

    Science.gov (United States)

    Meyer, Kristina; Müller, Niklas; Liu, Zuoye; Pfeifer, Thomas

    2016-12-20

    In time-resolved spectroscopy, it is a widespread belief that the temporal resolution is determined by the laser pulse duration. Recently, it was observed and shown that partially coherent laser pulses as they are provided by free-electron-laser (FEL) sources offer an alternative route to reach a temporal resolution below the average pulse duration. Here, we demonstrate the generation of partially coherent light in the laboratory like we observe it at FELs. We present the successful implementation of such statistically fluctuating pulses by using the pulse-shaping technique. These pulses exhibit an average pulse duration about 10 times larger than their bandwidth limit. The shaped pulses are then applied to transient-absorption measurements in the dye IR144. Despite the noisy characteristics of the laser pulses, features in the measured absorption spectra occurring on time scales much faster than the average pulse duration are resolved, thus proving the universality of the described noisy-pulse concept.

  18. Concave pulse shaping of a circularly polarized laser pulse from non-uniform overdense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Min Sup [School of Natural Science, UNIST, BanYeon-Ri 100, Ulju-gun, Ulsan, 689-798 (Korea, Republic of); Kulagin, Victor V. [Sternberg Astronomical Institute, Moscow State University, Universitetsky prosp. 13, Moscow, 119992 (Russian Federation); Suk, Hyyong, E-mail: hysuk@gist.ac.kr [Department of Physics and Photon Science, GIST, 123 Cheomdan-gwangiro, Buk-gu, Gwangju, 500-712 (Korea, Republic of)

    2015-03-20

    Pulse shaping of circularly polarized laser pulses in nonuniform overdense plasmas are investigated numerically. Specifically we show by two-dimensional particle-in-cell simulations the generation of a concave pulse front of a circularly polarized, a few tens of petawatt laser pulse from a density-tapered, overdense plasma slab. The concept used for the transverse-directional shaping is the differential transmittance depending on the plasma density, and the laser intensity. For suitable selection of the slab parameters for the concave pulse shaping, we studied numerically the pulse transmittance, which can be used for further parameter design of the pulse shaping. The concavely shaped circularly polarized pulse is expected to add more freedom in controlling the ion-beam characteristics in the RPDA regime. - Highlights: • Laser pulse shaping for a concave front by non-uniform overdense plasma was studied. • Particle-in-cell (PIC) simulations were used for the investigation. • A laser pulse can be shaped by a density-tapered overdense plasma. • The concave and sharp pulse front are useful in many laser–plasma applications. • They are important for ion acceleration, especially in the radiation pressure dominant regime.

  19. Noise Shaping Filter Compensating PWM Distortion for Fully Digital Amplifier

    Science.gov (United States)

    Yoneya, Akihiko

    The full-digital audio amplifiers have several merits such as a high power enabling a small size of the amplifier and digital implementation of the signal processing which allows desired precision of the processing except for the final stage switching amplifiers. Unfortunately, the pulse width modulation (PWM) causes signal distortions because of the non-linearity of the modulation from the viewpoint of the transient response. This paper proposes a compensation method of the PWM distortion with feedback approach. In the noise-shaping filter of the delta-sigma modulator to calculate the pulse codes for the PWM, the distortion caused by the PWM is evaluated and fed it back to compensate the distortion. Eventually the filter is implemented as a state-variable filter with non-linear feedback from the quantizer. The calculation of the filter elements is also described. By using proposed filters, PWM signals with small distortions and small floor noise can be obtained to realize high-fidelity audio amplifiers.

  20. Digital Pulse Modulation Amplifier (PMA) systems based on PEDEC control

    DEFF Research Database (Denmark)

    Nielsen, Karsten

    1999-01-01

    The paper extends previous research and presents a suite of novel high efficiency digital PMA topologies based on Pulse Edge Delay Error Correction (PEDEC). The practical results are very encouraging, showing that digital modulator performance is maintained throughout the subsequent power convers...... conversion. The topologies are believed to be the first implemented digital PMA systems including effective power stage error correction....

  1. Neutron-gamma discrimination based on bipolar trapezoidal pulse shaping using FPGAs in NE213

    Energy Technology Data Exchange (ETDEWEB)

    Esmaeili-sani, Vahid, E-mail: vaheed_esmaeely80@yahoo.com [Department of Nuclear Engineering and Physics, Amirkabir University of Technology, P.O. Box 4155-4494, Tehran (Iran, Islamic Republic of); Moussavi-zarandi, Ali; Akbar-ashrafi, Nafiseh; Boghrati, Behzad; Afarideh, Hossein [Department of Nuclear Engineering and Physics, Amirkabir University of Technology, P.O. Box 4155-4494, Tehran (Iran, Islamic Republic of)

    2012-12-01

    A technique employing neutron-gamma pulse shape discrimination (PSD) system that overcomes pile up limitations of previous methods to distinguish neutrons from gammas in scintillation detectors is described. The output signals of detectors were digitized and processed with a data acquisition system based on bipolar trapezoidal pulse shaping using Field programmable gate arrays (FPGA). FPGAs are capable of doing complex discrete signal processing algorithms with clock rates above 100 MHz. Their low cost, ease of use and selected dedicated hardware make them an ideal option for spectrometer systems.

  2. Pulse shape adjustment for the SLC damping ring kickers

    Energy Technology Data Exchange (ETDEWEB)

    Mattison, T.; Cassel, R.; Donaldson, A.; Fischer, H.; Gough, D.

    1991-05-01

    The difficulties with damping ring kickers that prevented operation of the SLAC Linear Collider in full multiple bunch mode have been overcome by shaping the current pulse to compensate for imperfections in the magnets. The risetime was improved by a peaking capacitor, with a tunable inductor to provide a locally flat pulse. The pulse was flattened by an adjustable droop inductor. Fine adjustment was provided by pulse forming line tuners driven by stepping motors. Further risetime improvement will be obtained by a saturating ferrite pulse sharpener. 4 refs., 3 figs.

  3. A Compact Nanosecond-Pulse Shaping System Based on Pulse Stacking in Fibres

    Institute of Scientific and Technical Information of China (English)

    SUI Zhan; LIN Hong-Huan; WANG Jian-Jun; ZHAO Hong-Ming; LI Ming-Zhong; QIAN Lie-Jia; ZHU He-Yuan; FAN Dian-Yuan

    2006-01-01

    @@ We demonstrate a compact pulse shaping system based on temporal stacking of pulses in fibres, by which synchronized pulses of ultrashort and nanosecond lasers can be obtained. The system may generate shape-controllable pulses with a fast rise time and high-resolution within a time window of ~2.2 ns by adjusting variable optical attenuators in the 32 fibre channels independently. With the help of optical amplifiers, the system delivers mJ-level pulses with a signal-to-noise ratio of~35 dB.

  4. A study on the pulse height resolution of organic scintillator digitized pulses

    Energy Technology Data Exchange (ETDEWEB)

    Belli, Francesco, E-mail: Francesco.Belli@enea.it [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, C.P. 65, Frascati I-00044, Rome (Italy); Esposito, Basilio; Marocco, Daniele; Riva, Marco [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, C.P. 65, Frascati I-00044, Rome (Italy)

    2013-10-15

    Highlights: ► The frequency analysis of pulses from a liquid scintillator detector is performed. ► The minimum sampling rate required to avoid PH degradation is determined. ► It is shown that interpolation methods increase the FoM for n/γ discrimination. -- Abstract: Organic scintillator detectors are widely used for neutron spectroscopy in fusion devices due to their good energy resolution and capability of neutron/gamma discrimination. Nowadays, scintillator pulses are commonly recorded by means of digital acquisition systems. These have several advantages, and in particular the possibility of off-line data reprocessing: however, the signal digitization can be a cause of degradation of the pulse height (PH) resolution (and therefore of the energy resolution obtained after pulse height spectra unfolding). In this work, the problem of how pulse digitization may influence the pulse height resolution is investigated. First, through downsampling of digitized scintillator pulses, we determine the minimum sampling rate required to avoid any degradation of the pulse height resolution. Secondly, we find that the application of interpolation methods to the digitized pulses does not affect the pulse height resolution, whereas it increases the figure of merit for neutron/gamma discrimination. These results are relevant to define the specifications for the digital acquisition systems of neutron detectors in present and future fusion devices such as JET and ITER.

  5. Pulse shape analysis in cryogenic detectors for rare event search

    Energy Technology Data Exchange (ETDEWEB)

    Hitzler, Ferdinand [Physik Department E15, Technische Universitaet Muenchen, 85748 Muenchen (Germany); Collaboration: CRESST-Collaboration

    2015-07-01

    Based on an established pulse shape analysis with an Artificial Neural Network (ANN) we investigate new network designs. To study this an extended pulse simulation is necessary and is therefore explained in this talk. Furthermore, we introduce ideas to increase the overall performance of the nets. First results concerning the cut efficiency and the purity of the signal with these new ANNs are shown.

  6. Subharmonic emissions from microbubbles: effect of the driving pulse shape.

    Science.gov (United States)

    Biagi, Elena; Breschi, Luca; Vannacci, Enrico; Masotti, Leonardo

    2006-11-01

    The aims of this work are to investigate the response of the ultrasonic contrast agents (UCA) insonified by different arbitrary-shaped pulses at different acoustic pressures and concentration of the contrast agent focusing on subharmonic emission. A transmission setup was developed in order to insonify the contrast agent contained in a measurement chamber. The transmitted ultrasonic signals were generated by an arbitrary wave generator connected to a linear power amplifier able to drive a single-element transducer. The transmitted ultrasonic pulses that passed through the contrast agent-filled chamber were received by a second transducer or a hydrophone aligned with the first one. The radio frequency (RF) signals were acquired by fast echographic multiparameters multi-image novel apparatus (FEMMINA), which is an echographic platform able to acquire ultrasonic signals in a real-time modality. Three sets of ultrasonic signals were devised in order to evaluate subharmonic response of the contrast agent respect with sinusoidal burst signals used as reference pulses. A decreasing up to 30 dB in subharmonic response was detected for a Gaussian-shaped pulse; differences in subharmonic emission up to 21 dB were detected for a composite pulse (two-tone burst) for different acoustic pressures and concentrations. Results from this experimentation demonstrated that the transmitted pulse shape strongly affects subharmonic emission in spite of a second harmonic one. In particular, the smoothness of the initial portion of the shaped pulses can inhibit subharmonic generation from the contrast agents respect with a reference sinusoidal burst signal. It also was shown that subharmonic generation is influenced by the amplitude and the concentration of the contrast agent for each set of the shaped pulses. Subharmonic emissions that derive from a nonlinear mechanism involving nonlinear coupling among different oscillation modes are strongly affected by the shape of the ultrasonic

  7. Drop Shaping by Laser-Pulse Impact

    NARCIS (Netherlands)

    Klein, A.L.; Bouwhuis, W.; Visser, C.W.; Lhuissier, H.E.; Sun, C.; Snoeijer, J.H.; Villermaux, E.; Lohse, D.; Gelderblom, H.

    2015-01-01

    We show how the deposition of laser energy induces propulsion and strong deformation of an absorbing liquid body. Combining high speed with stroboscopic imaging, we observe that a millimeter-sized dyed water drop hit by a millijoule nanosecond laser pulse propels forward at several meters per second

  8. Spatiotemporal vector pulse shaping of femtosecond laser pulses with a multi-pass two-dimensional spatial light modulator.

    Science.gov (United States)

    Esumi, Y; Kabir, M D; Kannari, F

    2009-10-12

    A novel non-interferometric vector pulse-shaping scheme is developed for femtosecond laser pulses using a two-dimensional spatial light modulator (2D-SLM). By utilizing spatiotemporal pulse shaping obtainable by the 2D-SLM, we demonstrate spatiotemporal vector pulse shaping for the first time.

  9. Digital Communication Using Chaotic Pulse Generators

    CERN Document Server

    Rulkov, N F; Tsimring, L S; Volkovskii, A R; Abarbanel, Henry D I; Larson, L; Yao, K

    1999-01-01

    Utilization of chaotic signals for covert communications remains a very promising practical application. Multiple studies indicated that the major shortcoming of recently proposed chaos-based communication schemes is their susceptibility to noise and distortions in communication channels. In this talk we discuss a new approach to communication with chaotic signals, which demonstrates good performance in the presence of channel distortions. This communication scheme is based upon chaotic signals in the form of pulse trains where intervals between the pulses are determined by chaotic dynamics of a pulse generator. The pulse train with chaotic interpulse intervals is used as a carrier. Binary information is modulated onto this carrier by the pulse position modulation method, such that each pulse is either left unchanged or delayed by a certain time, depending on whether ``0'' or ``1'' is transmitted. By synchronizing the receiver to the chaotic pulse train we can anticipate the timing of pulses corresponding to ...

  10. Versatile Stimulation Back-End With Programmable Exponential Current Pulse Shapes for a Retinal Visual Prosthesis.

    Science.gov (United States)

    Maghami, Mohammad Hossein; Sodagar, Amir M; Sawan, Mohamad

    2016-11-01

    This paper reports on the design, implementation, and test of a stimulation back-end, for an implantable retinal prosthesis. In addition to traditional rectangular pulse shapes, the circuit features biphasic stimulation pulses with both rising and falling exponential shapes, whose time constants are digitally programmable. A class-B second generation current conveyor is used as a wide-swing, high-output-resistance stimulation current driver, delivering stimulation current pulses of up to ±96 μA to the target tissue. Duration of the generated current pulses is programmable within the range of 100 μs to 3 ms. Current-mode digital-to-analog converters (DACs) are used to program the amplitudes of the stimulation pulses. Fabricated using the IBM 130 nm process, the circuit consumes 1.5×1.5 mm(2) of silicon area. According to the measurements, the DACs exhibit DNL and INL of 0.23 LSB and 0.364 LSB, respectively. Experimental results indicate that the stimuli generator meets expected requirements when connected to electrode-tissue impedance of as high as 25 k Ω. Maximum power consumption of the proposed design is 3.4 mW when delivering biphasic rectangular pulses to the target load. A charge pump block is in charge of the upconversion of the standard 1.2-V supply voltage to ±3.3V.

  11. All-digital pulse-expansion-based CMOS digital-to-time converter

    Science.gov (United States)

    Chen, Chun-Chi; Chu, Che-Hsun

    2017-02-01

    This paper presents a new all-digital CMOS digital-to-time converter (DTC) based on pulse expansion. Pulse expansion is achieved using an all-digital pulse-mixing scheme that can effectively improve the timing resolution and enable the DTC to be concise. Without requiring the Vernier principle or a costly digital-to-analog converter, the DTC comprises a pulse generator for generating a pulse, a pulse-expanding circuit (PEC) for programming timing generation, and a time subtractor for removing the time width of the pulse. The PEC comprises only a delay chain composed of proposed pulse-expanding units and a multiplexer. For accuracy enhancement, a pulse neutralization technique is presented to eliminate undesirable pulse variation. A 4-bit converter was fabricated in a 0.35-μ m Taiwan Semiconductor Manufacturing Company CMOS process and had a small area of nearly 0.045 mm2. Six chips were tested, all of which exhibited an improved resolution (approximately 16 ps) and low integral nonlinearity (less than ±0.4 least significant bit). The power consumption was 0.2 mW when the sample rate was 1M samples/s and the voltage supply was 3.3 V. The proposed DTC not only has favorable cost and power but also achieves an acceptable resolution without requiring an advanced CMOS process. This study is the first to use pulse expansion in digital-to-time conversion.

  12. Pulse shape control in a dual cavity laser: numerical modeling

    Science.gov (United States)

    Yashkir, Yuri

    2006-04-01

    We present a numerical model of the laser system for generating a special shape of the pulse: a steep peak at the beginning followed by a long pulse tail. Laser pulses of this nature are required for various applications (laser material processing, optical breakdown spectroscopy, etc.). The laser system consists of two "overlapped" cavities with different round-trip times. The laser crystal, the Q-switching element, the back mirror, and the output coupler are shared. A shorter pulse is generated in a short cavity. A small fraction of this pulse is injected into the long cavity as a seed. It triggers generation of the longer pulse. The output emission from this hybrid laser produces a required pulse shape. Parameters of the laser pulse (ratios of durations and energies of short- and long- pulse components) can be controlled through cavity length and the output coupler reflection. Modelling of the laser system is based on a set of coupled rate equations for dynamic variables of the system: the inverse population in an active laser media and photon densities in coupled cavities. Numerical experiments were provided with typical parameters of a Nd:YAG laser to study the system behaviour for different combinations of parameters.

  13. Pulse-Shaping-Based Nonlinear Microscopy: Development and Applications

    Science.gov (United States)

    Flynn, Daniel Christopher

    The combination of optical microscopy and ultrafast spectroscopy make the spatial characterization of chemical kinetics on the femtosecond time scale possible. Commercially available octave-spanning Ti:Sapphire oscillators with sub-8 fs pulse durations can drive a multitude of nonlinear transitions across a significant portion of the visible spectrum with minimal average power. Unfortunately, dispersion from microscope objectives broadens pulse durations, decreases temporal resolution and lowers the peak intensities required for driving nonlinear transitions. In this dissertation, pulse shaping is used to compress laser pulses after the microscope objective. By using a binary genetic algorithm, pulse-shapes are designed to enable selective two-photon excitation. The pulse-shapes are demonstrated in two-photon fluorescence of live COS-7 cells expressing GFP-variants mAmetrine and tdTomato. The pulse-shaping approach is applied to a new multiphoton fluorescence resonance energy transfer (FRET) stoichiometry method that quantifies donor and acceptor molecules in complex, as well as the ratio of total donor to acceptor molecules. Compared to conventional multi-photon imaging techniques that require laser tuning or multiple laser systems to selectively excite individual fluorophores, the pulse-shaping approach offers rapid selective multifluorphore imaging at biologically relevant time scales. By splitting the laser beam into two beams and building a second pulse shaper, a pulse-shaping-based pump-probe microscope is developed. The technique offers multiple imaging modalities, such as excited state absorption (ESA), ground state bleach (GSB), and stimulated emission (SE), enhancing contrast of structures via their unique quantum pathways without the addition of contrast agents. Pulse-shaping based pump-probe microscopy is demonstrated for endogenous chemical-contrast imaging of red blood cells. In the second section of this dissertation, ultrafast spectroscopic

  14. Femtosecond parabolic pulse shaping in normally dispersive optical fibers.

    Science.gov (United States)

    Sukhoivanov, Igor A; Iakushev, Sergii O; Shulika, Oleksiy V; Díez, Antonio; Andrés, Miguel

    2013-07-29

    Formation of parabolic pulses at femtosecond time scale by means of passive nonlinear reshaping in normally dispersive optical fibers is analyzed. Two approaches are examined and compared: the parabolic waveform formation in transient propagation regime and parabolic waveform formation in the steady-state propagation regime. It is found that both approaches could produce parabolic pulses as short as few hundred femtoseconds applying commercially available fibers, specially designed all-normal dispersion photonic crystal fiber and modern femtosecond lasers for pumping. The ranges of parameters providing parabolic pulse formation at the femtosecond time scale are found depending on the initial pulse duration, chirp and energy. Applicability of different fibers for femtosecond pulse shaping is analyzed. Recommendation for shortest parabolic pulse formation is made based on the analysis presented.

  15. Optical sinc-shaped Nyquist pulses of exceptional quality.

    Science.gov (United States)

    Soto, Marcelo A; Alem, Mehdi; Amin Shoaie, Mohammad; Vedadi, Armand; Brès, Camille-Sophie; Thévenaz, Luc; Schneider, Thomas

    2013-01-01

    Sinc-shaped Nyquist pulses possess a rectangular spectrum, enabling data to be encoded in a minimum spectral bandwidth and satisfying by essence the Nyquist criterion of zero inter-symbol interference (ISI). This property makes them very attractive for communication systems since data transmission rates can be maximized while the bandwidth usage is minimized. However, most of the pulse-shaping methods reported so far have remained rather complex and none has led to ideal sinc pulses. Here a method to produce sinc-shaped Nyquist pulses of very high quality is proposed based on the direct synthesis of a rectangular-shaped and phase-locked frequency comb. The method is highly flexible and can be easily integrated in communication systems, potentially offering a substantial increase in data transmission rates. Further, the high quality and wide tunability of the reported sinc-shaped pulses can also bring benefits to many other fields, such as microwave photonics, light storage and all-optical sampling.

  16. Optical sinc-shaped Nyquist pulses of exceptional quality

    Science.gov (United States)

    Soto, Marcelo A.; Alem, Mehdi; Amin Shoaie, Mohammad; Vedadi, Armand; Brès, Camille-Sophie; Thévenaz, Luc; Schneider, Thomas

    2013-12-01

    Sinc-shaped Nyquist pulses possess a rectangular spectrum, enabling data to be encoded in a minimum spectral bandwidth and satisfying by essence the Nyquist criterion of zero inter-symbol interference (ISI). This property makes them very attractive for communication systems since data transmission rates can be maximized while the bandwidth usage is minimized. However, most of the pulse-shaping methods reported so far have remained rather complex and none has led to ideal sinc pulses. Here a method to produce sinc-shaped Nyquist pulses of very high quality is proposed based on the direct synthesis of a rectangular-shaped and phase-locked frequency comb. The method is highly flexible and can be easily integrated in communication systems, potentially offering a substantial increase in data transmission rates. Further, the high quality and wide tunability of the reported sinc-shaped pulses can also bring benefits to many other fields, such as microwave photonics, light storage and all-optical sampling.

  17. Alpha-gamma pulse-shape discrimination in Gd3Al2Ga3O12 (GAGG):Ce3+ crystal scintillator using shape indicator

    Science.gov (United States)

    Tamagawa, Yoichi; Inukai, Yuji; Ogawa, Izumi; Kobayashi, Masaaki

    2015-09-01

    The pulse-shape discrimination (PSD) in a GAGG single-crystal scintillator was studied by using a shape indicator (SI) parameter of the optimal digital filter method. SI is one of the most useful PSD methods that use typical pulse shapes. Excellent discrimination between 0.662 MeV γ-rays and 5.48 MeV α-rays was achieved. For a cut at SI=0.0056, 99.95% of the γ-rays and only 0.22% of the α-rays were retained. Selection of background events (γ and α) in the GAGG scintillator was achieved by using the PSD method.

  18. Nonlinear Pulse Shaping in Fibres for Pulse Generation and Optical Processing

    Directory of Open Access Journals (Sweden)

    Sonia Boscolo

    2012-01-01

    Full Text Available The development of new all-optical technologies for data processing and signal manipulation is a field of growing importance with a strong potential for numerous applications in diverse areas of modern science. Nonlinear phenomena occurring in optical fibres have many attractive features and great, but not yet fully explored, potential in signal processing. Here, we review recent progress on the use of fibre nonlinearities for the generation and shaping of optical pulses and on the applications of advanced pulse shapes in all-optical signal processing. Amongst other topics, we will discuss ultrahigh repetition rate pulse sources, the generation of parabolic shaped pulses in active and passive fibres, the generation of pulses with triangular temporal profiles, and coherent supercontinuum sources. The signal processing applications will span optical regeneration, linear distortion compensation, optical decision at the receiver in optical communication systems, spectral and temporal signal doubling, and frequency conversion.

  19. The SPICE Digital Shape Kernel (DSK) Subsystem

    Science.gov (United States)

    Bachman, N. J.

    2017-06-01

    The DSK subsystem is the component of SPICE concerned with detailed shape models. The DSK subsystem enables SPICE-based applications to conveniently and efficiently use detailed shape data in geometry computations performed by SPICE routines.

  20. Influence of amplification on pulse shaping for coherent control applications

    CSIR Research Space (South Africa)

    Du Plessis, A

    2011-07-01

    Full Text Available of using low seed laser powers for amplification of shaped pulses in a typical setup for coherent control experiments. An acousto-optic programmable dispersive filter (Dazzler from FastLite) is used to shape 130 fs pulses before amplification... measured as such) for low and high seed powers. Clearly, at lower seed powers as in (a), the measured trace corresponds to approximately the 4:1 ratio expected, but at high seed powers this ratio changes towards 2:1, indicating the smaller of the two...

  1. Theoretical study on pulse-shaping of Stokes pulse with steep leading edge by two Brillouin amplifiers

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel configuration of two Brillouin amplifiers, which contains a main amplifier combined with a reshaping amplifier, is suggested to control pulse shape of Stokes pulses with steep leading edge. Dependences of pulse shapes on several parameters are numerically simulated. By changing the distance between the two amplifiers, the leading edge of amplified pulses can be finely adjusted. Smooth and symmetrical pulses or pulses with slow leading-edge are achieved. Theoretical researches prove that this system is fit for shaping pulses with steep leading edge, especially, for controlling leading edge of pulses. The results provide useful and necessary theoretical basis and guidance for the future experimental research.

  2. Digital pulse processing and electronic noise analysis for improving energy resolutions in planar TlBr detectors

    Energy Technology Data Exchange (ETDEWEB)

    Tada, Tsutomu, E-mail: tada.t@cyric.tohoku.ac.j [Cyclotron and Radioisotope Center, Tohoku University, 6-3 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Hitomi, Keitaro [Cyclotron and Radioisotope Center, Tohoku University, 6-3 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Tanaka, Tomonobu [Divisions of Electronics, Graduate School of Engineering, Tohoku Institute of Technology, 35-1 Yagiyama, Kasumi-cho, Taihakuku, Sendai, Miyagi 982-8577 (Japan); Wu, Yan; Kim, Seong-Yun; Yamazaki, Hiromichi [Cyclotron and Radioisotope Center, Tohoku University, 6-3 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Ishii, Keizo [Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, 6-6-1 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan)

    2011-05-11

    Digital pulse processing and electronic noise analysis are proposed for improving energy resolution in planar thallium bromide (TlBr) detectors. An energy resolution of 5.8% FWHM at 662 keV was obtained from a 0.5 mm thick planar TlBr detector at room temperature using a digitizer with a sampling rate of 100 MS/s and 8 bit resolution. The electronic noise in the detector-preamplifier system was measured as a function of pulse shaping time in order to investigate the optimum shaping time for the detector. The depth of interaction (DOI) in TlBr detectors for incident gamma-rays was determined by taking the ratio of pulse heights for fast-shaped to slow-shaped signals. FWHM energy resolution of the detector was improved from 5.8% to 4.2% by implementing depth correction and by using the obtained optimum shaping time.

  3. The shaping of a national ignition campaign pulsed waveform

    Energy Technology Data Exchange (ETDEWEB)

    Brunton, Gordon, E-mail: brunton2@llnl.gov [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Erbert, Gaylen; Browning, Don; Tse, Eddy [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer NIF pulse is generated using an electro-optic modulator to vary the intensity of light. Black-Right-Pointing-Pointer Electrical impulse generators, each with a 300 ps pulse Gaussian signal are utilized. Black-Right-Pointing-Pointer Adjusting the impulse amplitude for 140 impulses, produces a pulsed waveform. Black-Right-Pointing-Pointer System auto shapes 48 waveforms with to 275:1 contrast ratio with 3% absolute error. - Abstract: The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is a stadium-sized facility containing a 192 beam, 1.8 MJ, 500 TW ultraviolet laser system used for inertial confinement fusion research. For each experimental shot, NIF must deliver a precise amount of laser power on the target for successful and efficient target ignition, and these characteristics vary depending on the physics of the particular campaign. The precise temporal shape, energy and timing characteristics of a pulsed waveform target interaction are key components in meeting the experimental goals. Each NIF pulse is generated in the Master Oscillator Room (MOR) using an electro-optic modulator to vary the intensity of light in response to an electrical input. The electrical drive signal to the modulator is produced using a unique, high-performance arbitrary waveform generator (AWG). This AWG sums the output of 140 electrical impulse generators, each producing a 300 ps pulse width Gaussian signal separated in time by 250 ps. By adjusting the amplitudes and summing the 140 impulses, a pulsed waveform can be sculpted from a seed 45 ns square pulse. Using software algorithms written for NIF's Integrated Computer Control System (ICCS), the system is capable of autonomously shaping 48 unique experimental pulsed waveforms for each shot that have demonstrated up to 275:1 contrast ratio with {+-}3% absolute error averaged over any 2 ns interval, meeting the stringent pulse requirements needed to achieve ignition

  4. Current pulse shaping of the load current on PTS

    Directory of Open Access Journals (Sweden)

    Minghe Xia

    2016-02-01

    Full Text Available The typical rise time of PTS machine is ∼110 ns with about 10 MA peak current under short pulse mode when all 24 modules discharge simultaneously. By distributing the trigger times of 12 laser beams logically and adjusting the statues of the pulse output switches, longer rise-time pulse can be obtained on the PTS facility. Based on the required pulse shape, whole circuit simulations will be used to calculate the trigger times of each laser triggering gas switch and the status of the pulse output switches. The rise time of the current is determined by the time difference between the first and last trigged laser triggering gas switches. In order to trigger the laser triggering gas switch, sufficient laser power is needed to be sent into the gap of the gas switches. The gas pressure and voltage difference on the two electrodes of the gas switches also affect the triggering of the gas switches, and the voltage added on the gas switch is determined by its transition time. Traditionally the trigger time difference should be less than the transition time of the two neighboring modules. A new simulation model of PTS shows one can break this transition time limits. Series of current pulse shaping experiments have been investigated on the PTS (Primary Test Stand. As results, more than 5 MA peak current were successfully achieved on the load with a rise time of 600 ns. This study and experiments of the pulse shaping on PTS demonstrate the adaptable ability of the PTS for offering different waveform of mega ampere current pulse for different research purpose.

  5. Pulse shape discrimination in non-aromatic plastics

    Energy Technology Data Exchange (ETDEWEB)

    Paul Martinez, H.; Pawelczak, Iwona; Glenn, Andrew M.; Leslie Carman, M.; Zaitseva, Natalia; Payne, Stephen

    2015-01-21

    Recently it has been demonstrated that plastic scintillators have the ability to distinguish neutrons from gamma rays by way of pulse shape discrimination (PSD). This discovery has lead to new materials and new capabilities. Here we report our work with the effects of aromatic, non-aromatic, and mixed aromatic/non-aromatic matrices have on the performance of PSD plastic scintillators.

  6. Partial discharge pulse shape recognition using an inductive loop sensor

    Science.gov (United States)

    Martínez-Tarifa, J. M.; Robles, G.; Rojas-Moreno, M. V.; Sanz-Feito, J.

    2010-10-01

    Partial discharges (PD) are a clear ageing agent on insulating materials used in high-voltage electrical machines and cables. For this reason, there is increasing interest in measuring this phenomenon in an effort to forecast unexpected failures in electrical equipment. In order to focus on harmful discharges, PD pulse shape analysis is being used as an insulation defect identification technique. In this paper, a simple, inexpensive and high-frequency inductive loop sensor will be used to detect and acquire PD pulses. Several measurements will be made on some controlled test cell geometries in order to characterize PD pulse shapes for different discharge sources. The sensor identification capability has been checked in an insulation system where two simultaneous PD sources were active.

  7. Pulse-shaping based two-photon FRET stoichiometry.

    Science.gov (United States)

    Flynn, Daniel C; Bhagwat, Amar R; Brenner, Meredith H; Núñez, Marcos F; Mork, Briana E; Cai, Dawen; Swanson, Joel A; Ogilvie, Jennifer P

    2015-02-09

    Förster Resonance Energy Transfer (FRET) based measurements that calculate the stoichiometry of intermolecular interactions in living cells have recently been demonstrated, where the technique utilizes selective one-photon excitation of donor and acceptor fluorophores to isolate the pure FRET signal. Here, we present work towards extending this FRET stoichiometry method to employ two-photon excitation using a pulse-shaping methodology. In pulse-shaping, frequency-dependent phases are applied to a broadband femtosecond laser pulse to tailor the two-photon excitation conditions to preferentially excite donor and acceptor fluorophores. We have also generalized the existing stoichiometry theory to account for additional cross-talk terms that are non-vanishing under two-photon excitation conditions. Using the generalized theory we demonstrate two-photon FRET stoichiometry in live COS-7 cells expressing fluorescent proteins mAmetrine as the donor and tdTomato as the acceptor.

  8. Neutron and Gamma Ray Pulse Shape Discrimination with Polyvinyltoluene

    Energy Technology Data Exchange (ETDEWEB)

    Lintereur, Azaree T.; Ely, James H.; Stave, Jean A.; McDonald, Benjamin S.

    2012-03-01

    The goal of this was research effort was to test the ability of two poly vinyltoluene research samples to produce recordable, distinguishable signals in response to gamma rays and neutrons. Pulse shape discrimination was performed to identify if the signal was generated by a gamma ray or a neutron. A standard figure of merit for pulse shape discrimination was used to quantify the gamma-neutron pulse separation. Measurements were made with gamma and neutron sources with and without shielding. The best figure of merit obtained was 1.77; this figure of merit was achieved with the first sample in response to an un-moderated 252Cf source shielded with 5.08 cm of lead.

  9. Shaping and timing gradient pulses to reduce MRI acoustic noise.

    Science.gov (United States)

    Segbers, Marcel; Rizzo Sierra, Carlos V; Duifhuis, Hendrikus; Hoogduin, Johannes M

    2010-08-01

    A method to reduce the acoustic noise generated by gradient systems in MRI has been recently proposed; such a method is based on the linear response theory. Since the physical cause of MRI acoustic noise is the time derivative of the gradient current, a common trapezoid current shape produces an acoustic gradient coil response mainly during the rising and falling edge. In the falling edge, the coil acoustic response presents a 180 degrees phase difference compared to the rising edge. Therefore, by varying the width of the trapezoid and keeping the ramps constant, it is possible to suppress one selected frequency and its higher harmonics. This value is matched to one of the prominent resonance frequencies of the gradient coil system. The idea of cancelling a single frequency is extended to a second frequency, using two successive trapezoid-shaped pulses presented at a selected interval. Overall sound pressure level reduction of 6 and 10 dB is found for the two trapezoid shapes and a single pulse shape, respectively. The acoustically optimized pulse shape proposed is additionally tested in a simulated echo planar imaging readout train, obtaining a sound pressure level reduction of 12 dB for the best case.

  10. Laser pulse-shape dependence of Compton scattering

    CERN Document Server

    Titov, Alexander I; Shibata, Takuya; Hosaka, Atsushi; Takabe, Hideaki

    2014-01-01

    Compton scattering of short and ultra short (sub-cycle) laser pulses off mildly relativistic electrons is considered within a QED framework. The temporal shape of the pulse is essential for the differential cross section as a function of the energy of the scattered photon at fixed observation angle. The partly integrated cross section is sensitive to the non-linear dynamics resulting in a large enhancement of the cross section for short and, in particular, for ultra-short flat-top pulse envelopes which can reach several orders of magnitude, as compared with the case of a long pulse. Such effects can be studied experimentally and must be taken into account in Monte-Carlo/transport simulations of %$e^+e^-$ pair production in the interaction of electrons and photons in a strong laser field.

  11. Spectrotemporal shaping of seeded free-electron laser pulses.

    Science.gov (United States)

    Gauthier, David; Ribič, Primož Rebernik; De Ninno, Giovanni; Allaria, Enrico; Cinquegrana, Paolo; Danailov, Miltcho Bojanov; Demidovich, Alexander; Ferrari, Eugenio; Giannessi, Luca; Mahieu, Benoît; Penco, Giuseppe

    2015-09-11

    We demonstrate the ability to control and shape the spectrotemporal content of extreme-ultraviolet (XUV) pulses produced by a seeded free-electron laser (FEL). The control over the spectrotemporal properties of XUV light was achieved by precisely manipulating the linear frequency chirp of the seed laser. Our results agree with existing theory, which allows us to retrieve the temporal properties (amplitude and phase) of the FEL pulse from measurements of the spectra as a function of the FEL operating parameters. Furthermore, we show the first direct evidence of the full temporal coherence of FEL light and generate Fourier limited pulses by fine-tuning the FEL temporal phase. The possibility of tailoring the spectrotemporal content of intense short-wavelength pulses represents the first step towards efficient nonlinear optics in the XUV to x-ray spectral region and will enable precise manipulation of core-electron excitations using the methods of coherent quantum control.

  12. Laboratory Transferability of Optimally Shaped Laser Pulses for Quantum Control

    CERN Document Server

    Tibbetts, Katharine Moore; Rabitz, Herschel

    2013-01-01

    Optimal control experiments can readily identify effective shaped laser pulses, or "photonic reagents", that achieve a wide variety of objectives. For many practical applications, an important criterion is that a particular photonic reagent prescription still produce a good, if not optimal, target objective yield when transferred to a different system or laboratory, {even if the same shaped pulse profile cannot be reproduced exactly. As a specific example, we assess the potential for transferring optimal photonic reagents for the objective of optimizing a ratio of photoproduct ions from a family of halomethanes through three related experiments.} First, applying the same set of photonic reagents with systematically varying second- and third-order chirp on both laser systems generated similar shapes of the associated control landscape (i.e., relation between the objective yield and the variables describing the photonic reagents). Second, optimal photonic reagents obtained from the first laser system were found...

  13. Mathematical method for optimal digitization and discrimination of scintillation detectors' pulses

    Science.gov (United States)

    Saleh, H. I.

    2015-12-01

    The crystal identification and particle identification require applying pulse shape discrimination (PSD) methods to differentiate between two or more types of scintillation pulses according to their decay times. The sampling rate and the number of used samples of scintillation pulses significantly affect the performance and the complexity of the PSD. Despite their importance, there is no method in the literature, to the best of our knowledge, regarding how to optimally select these parameters. This paper introduces a mathematical analysis of the frequency spectra to determine the most discriminated frequency band of any two different pulse-types. The proposed analysis showed that the most discriminated frequency band depends on the two decay times of the pulse-types. Based on this analysis, a digitization criterion is proposed to determine the optimum sampling rate, number of used samples and the cutoff frequency of the anti-aliasing filter. Furthermore, determining the most discriminated frequency band reduces the number of needed frequency components and provides the highest discrimination performance with the lowest number of required computations. The proposed digitization criterion is applied on two pulse-types with different decay times (20 ns and 40 ns) and shows that the most discriminated frequency is 8 MHz . It also recommends using 32 MHz sampling rate, 8 samples and an anti-aliasing filter with 10 MHz cutoff frequency for these two pulse-types.

  14. Comparison of Performance Metrics for QPSK and OQPSK Transmission Using Root Raised Cosine and Raised Cosine Pulse shaping Filters for Applications in Mobile Communication

    CERN Document Server

    Chattopadhyay, Sudipta

    2009-01-01

    Quadrature Phase Shift Keying (QPSK) and Offset Quadrature Phase Shift Keying (OQPSK) are two well accepted modulation techniques used in Code Division Multiple Access (CDMA) system. The Pulse Shaping Filters play an important role in digital transmission. The type of Pulse Shaping Filter used, and its behavior would influence the performance of the communication system. This in turn, would have an effect on the performance of the Mobile Communication system, in which the digital communication technique has been employed. In this paper we have presented comparative study of some performance parameters or performance metrics of a digital communication system like, Error Vector Magnitude (EVM), Magnitude Error, Phase Error and Bandwidth Efficiency for a QPSK transmission system. Root Raised Cosine (RRC) and Raised Cosine (RC) Pulse shaping filters have been used for comparison. The measurement results serve as a guideline to the system designer to select the proper pulse shaping filter with the appropriate valu...

  15. Scintillation time dependence and pulse shape discrimination in liquid argon

    CERN Document Server

    Lippincott, W H; Gastler, D; Hime, A; Kearns, E; McKinsey, D N; Nikkel, J A; Stonehill, L C

    2008-01-01

    Using a single-phase liquid argon detector with a signal yield of 4.85 photoelectrons per keV of electronic-equivalent recoil energy (keVee), we measure the scintillation time dependence of both electronic and nuclear recoils in liquid argon down to 5 keVee. We develop two methods of pulse shape discrimination to distinguish between electronic and nuclear recoils. Using one of these methods, we measure a background and statistics-limited level of electronic recoil contamination to be $7.6\\times10^{-7}$ between 60 and 128 keV of nuclear recoil energy (keVr) for a nuclear recoil acceptance of 50% with no nuclear recoil-like events above 72 keVr. Finally, we develop a maximum likelihood method of pulse shape discrimination using the measured scintillation time dependence and predict the sensitivity to WIMP-nucleon scattering in three configurations of a liquid argon dark matter detector.

  16. Analysis of ultra-short pulse shaping with programmable amplitude and phase masks

    Institute of Scientific and Technical Information of China (English)

    Shanhong You; Weidong Shao; Wenfeng Cai; Honglong Cao; M. Kavehrad

    2011-01-01

    @@ Specified ultra-short pulse waveforms could be synthesized with high-resolution zero-dispersion pulse shaping system.The system and parameters are analyzed and discussed.The pulse shaping system with optimized parameters could resolve the frequency components of ultra-broad bandwidth pulse and prevent the spatial shaping of individual frequency components.The specified waveforms, Meyer wavelet and square root raised cosine pulses, are generated with programmable amplitude and phase masks.%Specified ultra-short pulse waveforms could be synthesized with high-resolution zero-dispersion pulse shaping system. The system and parameters are analyzed and discussed. The pulse shaping system with optimized parameters could resolve the frequency components of ultra-broad bandwidth pulse and prevent the spatial shaping of individual frequency components. The specified waveforms, Meyer wavelet and square root raised cosine pulses, are generated with programmable amplitude and phase masks.

  17. Software emulator of nuclear pulse generation with different pulse shapes and pile-up

    Science.gov (United States)

    Pechousek, Jiri; Konecny, Daniel; Novak, Petr; Kouril, Lukas; Kohout, Pavel; Celiktas, Cuneyt; Vujtek, Milan

    2016-08-01

    The optimal detection of output signals from nuclear counting devices represents one of the key physical factors that govern accuracy and experimental reproducibility. In this context, the fine calibration of the detector under diverse experimental scenarios, although time costly, is necessary. However this process can be rendered easier with the use of systems that work in lieu of emulators. In this report we describe an innovative programmable pulse generator device capable to emulate the scintillation detector signals, in a way to mimic the detector performances under a variety of experimental conditions. The emulator generates a defined number of pulses, with a given shape and amplitude in the form of a sampled detector signal. The emulator output is then used off-line by a spectrometric system in order to set up its optimal performance. Three types of pulse shapes are produced by our device, with the possibility to add noise and pulse pile-up effects into the signal. The efficiency of the pulse detection, pile-up rejection and/or correction, together with the dead-time of the system, are therein analyzed through the use of some specific algorithms for pulse processing, and the results obtained validate the beneficial use of emulators for the accurate calibration process of spectrometric systems.

  18. Software emulator of nuclear pulse generation with different pulse shapes and pile-up

    Energy Technology Data Exchange (ETDEWEB)

    Pechousek, Jiri, E-mail: jiri.pechousek@upol.cz [Department of Experimental Physics, Faculty of Science, Palacky University, 17. listopadu 1192/12, 771 46 Olomouc (Czech Republic); Konecny, Daniel [Department of Optics, Faculty of Science, Palacky University, 17. listopadu 1192/12, 77 146 Olomouc (Czech Republic); Novak, Petr; Kouril, Lukas; Kohout, Pavel [Department of Experimental Physics, Faculty of Science, Palacky University, 17. listopadu 1192/12, 771 46 Olomouc (Czech Republic); Celiktas, Cuneyt [Department of Physics, Faculty of Science, Ege University, Bornova, Izmir (Turkey); Vujtek, Milan [Department of Experimental Physics, Faculty of Science, Palacky University, 17. listopadu 1192/12, 771 46 Olomouc (Czech Republic)

    2016-08-21

    The optimal detection of output signals from nuclear counting devices represents one of the key physical factors that govern accuracy and experimental reproducibility. In this context, the fine calibration of the detector under diverse experimental scenarios, although time costly, is necessary. However this process can be rendered easier with the use of systems that work in lieu of emulators. In this report we describe an innovative programmable pulse generator device capable to emulate the scintillation detector signals, in a way to mimic the detector performances under a variety of experimental conditions. The emulator generates a defined number of pulses, with a given shape and amplitude in the form of a sampled detector signal. The emulator output is then used off-line by a spectrometric system in order to set up its optimal performance. Three types of pulse shapes are produced by our device, with the possibility to add noise and pulse pile-up effects into the signal. The efficiency of the pulse detection, pile-up rejection and/or correction, together with the dead-time of the system, are therein analyzed through the use of some specific algorithms for pulse processing, and the results obtained validate the beneficial use of emulators for the accurate calibration process of spectrometric systems.

  19. Shaped pulse electric-field construction and interferometric characterization: The SPECIFIC method

    CERN Document Server

    Coughlan, Matthew A; Weber, Stefan M; Bowlan, Pamela; Trebino, Rick; Levis, Robert J

    2009-01-01

    A method is reported for creating, generating, and measuring parametrically shaped pulses for time-bandwidth product >>5, which consists of a parametric pulse-shaping algorithm, a spatial light modulation system and a single shot interferometric characterization scheme (SEA TADPOLE) . The utilization of these tools marks the inception of a new method called SPECIFIC, shaped-pulse electric-field construction and interferometric characterization, capable of producing complex shaped laser pulses for coherent control experiments.

  20. Noninvasive continuous monitoring of digital pulse waves during hemodialysis

    DEFF Research Database (Denmark)

    Burkert, Antje; Scholze, Alexandra; Tepel, Martin

    2009-01-01

    Intermittent hemodynamic instability during hemodialysis treatment is a frequent complication in patients with end-stage renal failure. A noninvasive method for continuous hemodynamic monitoring is needed. We used noninvasive digital photoplethysmography and an algorithm for continuous, investiga......Intermittent hemodynamic instability during hemodialysis treatment is a frequent complication in patients with end-stage renal failure. A noninvasive method for continuous hemodynamic monitoring is needed. We used noninvasive digital photoplethysmography and an algorithm for continuous......, investigator-independent, automatic analysis of digital volume pulse in 10 healthy subjects and in 20 patients with end-stage renal failure during the hemodialysis session. The reflective index was defined representing the diastolic component of the digital pulse wave. The properties of the reflective index...... were studied in healthy control subjects (n=10). An increased reflective index was due to increased peripheral pulse wave reflection (e.g., vasoconstriction). During a hemodialysis session, the reflective index increased significantly from 36+/-3 arbitrary units to 41+/-3 arbitrary units (n=20; p...

  1. Influence of Pulse Shaping Filters on PAPR Performance of Underwater 5G Communication System Technique: GFDM

    Directory of Open Access Journals (Sweden)

    Jinqiu Wu

    2017-01-01

    Full Text Available Generalized frequency division multiplexing (GFDM is a new candidate technique for the fifth generation (5G standard based on multibranch multicarrier filter bank. Unlike OFDM, it enables the frequency and time domain multiuser scheduling and can be implemented digitally. It is the generalization of traditional OFDM with several added advantages like the low PAPR (peak to average power ratio. In this paper, the influence of the pulse shaping filter on PAPR performance of the GFDM system is investigated and the comparison of PAPR in OFDM and GFDM is also demonstrated. The PAPR is restrained by selecting proper parameters and filters to make the underwater acoustic communication more efficient.

  2. Pulse shapes and surface effects in segmented germanium detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lenz, Daniel

    2010-03-24

    It is well established that at least two neutrinos are massive. The absolute neutrino mass scale and the neutrino hierarchy are still unknown. In addition, it is not known whether the neutrino is a Dirac or a Majorana particle. The GERmanium Detector Array (GERDA) will be used to search for neutrinoless double beta decay of {sup 76}Ge. The discovery of this decay could help to answer the open questions. In the GERDA experiment, germanium detectors enriched in the isotope {sup 76}Ge are used as source and detector at the same time. The experiment is planned in two phases. In the first, phase existing detectors are deployed. In the second phase, additional detectors will be added. These detectors can be segmented. A low background index around the Q value of the decay is important to maximize the sensitivity of the experiment. This can be achieved through anti-coincidences between segments and through pulse shape analysis. The background index due to radioactive decays in the detector strings and the detectors themselves was estimated, using Monte Carlo simulations for a nominal GERDA Phase II array with 18-fold segmented germanium detectors. A pulse shape simulation package was developed for segmented high-purity germanium detectors. The pulse shape simulation was validated with data taken with an 19-fold segmented high-purity germanium detector. The main part of the detector is 18-fold segmented, 6-fold in the azimuthal angle and 3-fold in the height. A 19th segment of 5mm thickness was created on the top surface of the detector. The detector was characterized and events with energy deposited in the top segment were studied in detail. It was found that the metalization close to the end of the detector is very important with respect to the length of the of the pulses observed. In addition indications for n-type and p-type surface channels were found. (orig.)

  3. Mismatch-Shaping Serial Digital-to-Analog Converter

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper; Moon, Un-Ku; Temes, Gabor C.

    1999-01-01

    A simple but accurate pseudo-passive mismatch-shaping D/A converter is described. A digital state machine is used to control the switching sequence of a symmetric two-capacitor network that performs the D/A conversion. The error caused by capacitor mismatch is uncorrelated with the input signal a...

  4. Digitizing the Seminar Paper. A graduate student perspective on how digital tools shape scholarship

    Directory of Open Access Journals (Sweden)

    Brian Sarnacki

    2012-06-01

    Full Text Available In the early twentieth century, Grand Rapids, Michigan addressed a major political scandal, which was the tipping point of municipal politics in Grand Rapids between politics rooted in personal connections and those centered on business-like administration. However, reform moved slowly, hindered by the social and spatial relationships of the élite. Using digital tools in a digital history seminar shaped my analysis of these personal and spatial relations. As a vital step in my research process, the construction of a digital project not only informed my written argument, but also fundamentally shaped it. It also reveals the importance of small scale digital research projects, made accessible through the use of open access tools, in the ultimate widespread adoption of the digital humanities.

  5. A direct digital synthesis chirped pulse Fourier transform microwave spectrometer.

    Science.gov (United States)

    Finneran, Ian A; Holland, Daniel B; Carroll, P Brandon; Blake, Geoffrey A

    2013-08-01

    Chirped pulse Fourier transform microwave (CP-FTMW) spectrometers have become the instrument of choice for acquiring rotational spectra, due to their high sensitivity, fast acquisition rate, and large bandwidth. Here we present the design and capabilities of a recently constructed CP-FTMW spectrometer using direct digital synthesis (DDS) as a new method for chirped pulse generation, through both a suite of extensive microwave characterizations and deep averaging of the 10-14 GHz spectrum of jet-cooled acetone. The use of DDS is more suited for in situ applications of CP-FTMW spectroscopy, as it reduces the size, weight, and power consumption of the chirp generation segment of the spectrometer all by more than an order of magnitude, while matching the performance of traditional designs. The performance of the instrument was further improved by the use of a high speed digitizer with dedicated signal averaging electronics, which facilitates a data acquisition rate of 2.1 kHz.

  6. Descriptor Based Analysis of Digital 3D Shapes

    DEFF Research Database (Denmark)

    Welnicka, Katarzyna

    challenges. One such challenge, which is addressed in this thesis, is to develop computational methods for classifying shapes which are in agreement with the human way of understanding and classifying shapes. In this dissertation we first present a shape descriptor based on the process of diffusion......Analysis and processing of 3D digital shapes is a significant research area with numerous medical, industrial, and entertainment applications which has gained enormously in importance as optical scanning modalities have started to make acquired 3D geometry commonplace. The area holds many......, in conjunction with the method of Reeb graphs for skeletonization, it is an effective tool for generating scale dependent skeletons of shapes represented as 3D triangle meshes. The second part of the thesis aims at capturing the style phenomenon. The style of an object is easily recognized by humans...

  7. Electron - nuclear recoil discrimination by pulse shape analysis

    CERN Document Server

    Elbs, J; Collin, E; Godfrin, H; Suvorova, O

    2007-01-01

    In the framework of the ``ULTIMA'' project, we use ultra cold superfluid 3He bolometers for the direct detection of single particle events, aimed for a future use as a dark matter detector. One parameter of the pulse shape observed after such an event is the thermalization time constant. Until now it was believed that this parameter only depends on geometrical factors and superfluid 3He properties, and that it is independent of the nature of the incident particles. In this report we show new results which demonstrate that a difference for muon- and neutron events, as well as events simulated by heater pulses exist. The possibility to use this difference for event discrimination in a future dark matter detector will be discussed.

  8. High extinction amplitude modulation in ultrashort pulse shaping

    CERN Document Server

    Lin, Yen-Wei

    2016-01-01

    We explored the issues related to the resolution and the modulation extinction when filtering the spectrum of a UV femtosecond laser with a standard ultrashort pulse shaper. We have learned that a higher pulse shaping resolution often requires a larger working beam size or a higher density grating for greater dispersion. However, these approaches also introduce more optical errors and degrade the extinction. In this work, we examined specifics of each component to determine the best configuration of our spectral filtering setup. As a proof-of-concept demonstration, we utilized elements available as standard products and achieved 100 GHz filtering resolution with high extinction at the UV-A wavelength, which is superb in this wavelength range. The high extinction spectral filtering is especially important while modifying a broadband laser for the optical control of molecule's internal state.

  9. Pulse-shape discrimination in the IGEX experiment

    Science.gov (United States)

    González, D.; Morales, J.; Cebrián, S.; García, E.; Irastorza, I. G.; Morales, A.; Ortiz de Solórzano, A.; Puimedón, J.; Sarsa, M. L.; Villar, J. A.; Aalseth, C. E.; Avignone, F. T.; Brodzinski, R. L.; Hensley, W. K.; Miley, H. S.; Reeves, J. H.; Kirpichnikov, I. V.; Vasenko, A. A.; Klimenko, A. A.; Osetrov, S. B.; Smolnikov, A. A.; Vasiliev, S. I.; Pogosov, V. S.; Tamanyan, A. G.

    2003-12-01

    The IGEX experiment has been operating enriched germanium detectors in the Canfranc Underground Laboratory (Spain) in a search for the neutrinoless double decay of 76Ge. The implementation of pulse-shape discrimination techniques to reduce the radioactive background is described in detail. This analysis has been applied to a fraction of the IGEX data, leading to a rejection of ˜60% of their background, in the region of interest (from 2 to 2.5 MeV), down to ˜0.09 c/ keV kg yr .

  10. Pulse-shape discrimination in the IGEX experiment

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, D.; Morales, J. E-mail: jmorales@posta.unizar.es; Cebrian, S.; Garcia, E.; Irastorza, I.G.; Morales, A.; Ortiz de Solorzano, A.; Puimedon, J.; Sarsa, M.L.; Villar, J.A.; Aalseth, C.E.; Avignone, F.T.; Brodzinski, R.L.; Hensley, W.K.; Miley, H.S.; Reeves, J.H.; Kirpichnikov, I.V.; Vasenko, A.A.; Klimenko, A.A.; Osetrov, S.B.; Smolnikov, A.A.; Vasiliev, S.I.; Pogosov, V.S.; Tamanyan, A.G

    2003-12-11

    The IGEX experiment has been operating enriched germanium detectors in the Canfranc Underground Laboratory (Spain) in a search for the neutrinoless double decay of {sup 76}Ge. The implementation of pulse-shape discrimination techniques to reduce the radioactive background is described in detail. This analysis has been applied to a fraction of the IGEX data, leading to a rejection of {approx}60% of their background, in the region of interest (from 2 to 2.5 MeV), down to {approx}0.09 c/keV kg yr.

  11. Polystyrene-based scintillator with pulse-shape discrimination capability

    Energy Technology Data Exchange (ETDEWEB)

    Zhmurin, P.N.; Lebedev, V.N.; Titskaya, V.D.; Adadurov, A.F., E-mail: adadurov@isma.kharkov.ua; Elyseev, D.A.; Pereymak, V.N.

    2014-10-11

    Polystyrene-based scintillators with 2-phenyl-5-(4-tert-butylephenyl)-1,3,4-oxadiazole (tert-BuPPD) or 2,5-di-(3-methylphenyl)-1,3,4 oxadiazole (m-DMePPD) are proposed for pulse-shape n/γ-discrimination. These scintillators have improved mechanical properties, long operational time and high n/γ discrimination parameter – figure of merit (1.49 and 1.81 in a wide energy region), so they can be used as detectors of fast neutrons in the presence of gamma radiation background.

  12. A hybrid digital-analog long pulse integrator

    Science.gov (United States)

    Strait, E. J.; Broesch, J. D.; Snider, R. T.; Walker, M. L.

    1997-01-01

    A digital-analog integrator has been developed for use with inductive magnetic sensors in long-pulse tokamaks. Continuous compensation of input offsets is accomplished by alternating analog-to-digital convertor samples from the sensor and a dummy load, while a RC network provides passive integration between samples. Typically a sampling rate of 10 kHz is used. In operational tests on the DIII-D tokamak, digital and analog integration of tokamak data show good agreement. The output drift error during a 1200 s integration interval corresponds to a few percent of the anticipated signal for poloidal field probes in International Thermonuclear Experimental Reactor, and bench tests suggest that the error can be reduced further.

  13. Effect of Initial Chirping and Pulse Shape on 10 Gb/s Optical Pulse Transmission in Birefringent Nonlinear Fibers

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Numerical method to solve the problem related with theinteractive effect of dispersion (both chromatic dispersion and polarization mode dispersion) and nonlinearity on optical pulse transmission is present. Evolutions of pulses with various initial chirping and shape at bit-rate of 10 Gb/s are simulated and compared. Gaussian pulse with appropriate prechirping is propitious for high bit-rate transmission.

  14. Spectrum library concept and pulse shape analysis in liquid scintillation counting

    Energy Technology Data Exchange (ETDEWEB)

    Kaihola, L. [Wallac Oy, Turku (Finland)

    1997-03-01

    Wallac introduced in 1990 a new absolute liquid scintillation counting (LSC) method, Digital Overlay Technique (DOT) to correct for quench. This method allows quantization of multilabel samples by referring to library spectra which are generated against chemical and color quench indices at the factory. The libraries can further be expanded to any beta emitter by user with a method called fine tuning, which can be carried out even with a single sample. Spectrum libraries are created over the whole spectrum range of the radionuclide and allow automatic identification of a single label beta emitting radionuclide, called Easy Count method. Another improvement in LSC is commercial introduction of Pulse Shape Analysis (PSA) in 1986 by Wallac. This method recognizes alpha particle decay by pulse shape and leads to excellent sensitivity in alpha counting because most of the background signal in LSC comprises of short or beta like pulses. PSA detects alpha events in the presence of high excess of beta activity over alphas, up to a ratio 100000 to 1. (orig.)

  15. Pulse shaping effects on weld porosity in laser beam spot welds : contrast of long- & short- pulse welds.

    Energy Technology Data Exchange (ETDEWEB)

    Ellison, Chad M. (Honeywell FM& T, Kansas City, MO); Perricone, Matthew J. (R.J. Lee Group, Inc., Monroeville, PA); Faraone, Kevin M. (BWX Technologies, Inc., Lynchburg, VA); Norris, Jerome T.

    2007-10-01

    Weld porosity is being investigated for long-pulse spot welds produced by high power continuous output lasers. Short-pulse spot welds (made with a pulsed laser system) are also being studied but to a much small extent. Given that weld area of a spot weld is commensurate with weld strength, the loss of weld area due to an undefined or unexpected pore results in undefined or unexpected loss in strength. For this reason, a better understanding of spot weld porosity is sought. Long-pulse spot welds are defined and limited by the slow shutter speed of most high output power continuous lasers. Continuous lasers typically ramp up to a simmer power before reaching the high power needed to produce the desired weld. A post-pulse ramp down time is usually present as well. The result is a pulse length tenths of a second long as oppose to the typical millisecond regime of the short-pulse pulsed laser. This study will employ a Lumonics JK802 Nd:YAG laser with Super Modulation pulse shaping capability and a Lasag SLS C16 40 W pulsed Nd:YAG laser. Pulse shaping will include square wave modulation of various peak powers for long-pulse welds and square (or top hat) and constant ramp down pulses for short-pulse welds. Characterization of weld porosity will be performed for both pulse welding methods.

  16. Pulse-Shape Control in an All Fiber Multi-Wavelength Doppler Lidar

    Directory of Open Access Journals (Sweden)

    Töws Albert

    2016-01-01

    Full Text Available Pulse distortion during amplification in fiber amplifiers due to gain saturation and cross talk in a multi-wavelength Doppler lidar are discussed. We present a feedback control technique which is capable of adjusting any predefined pulse shape and show some examples of feedback controlled pulse shapes.

  17. Synthesis of picosecond pulses by spectral compression and shaping of femtosecond pulses in engineered quadratic nonlinear media.

    Science.gov (United States)

    Marangoni, M; Brida, D; Conforti, M; Capobianco, A D; Manzoni, C; Baronio, F; Nalesso, G F; De Angelis, C; Ramponi, R; Cerullo, G

    2009-02-01

    Narrow-bandwidth picosecond pulses of predetermined spectral and temporal shapes are generated with high efficiency by frequency conversion of femtosecond pulses in lithium tantalate crystals with engineered quasi-phase-matching structures. We give examples of the synthesis of Gaussian and super-Gaussian picosecond pulses and also of a pair of synchronized phase-coherent picosecond pulses with a predetermined carrier-frequency difference.

  18. Pulse shape discrimination for Gerda Phase I data

    Energy Technology Data Exchange (ETDEWEB)

    Agostini, M.; Bode, T.; Budjas, D.; Janicsko Csathy, J.; Lazzaro, A.; Schoenert, S. [Technische Universitaet Muenchen, Physik Department and Excellence Cluster Universe, Muenchen (Germany); Allardt, M.; Barros, N.; Domula, A.; Lehnert, B.; Wester, T.; Zuber, K. [Technische Universitaet Dresden, Institut fuer Kern- und Teilchenphysik, Dresden (Germany); Andreotti, E. [Institute for Reference Materials and Measurements, Geel (Belgium); Eberhard Karls Universitaet Tuebingen, Physikalisches Institut, Tuebingen (Germany); Bakalyarov, A.M.; Belyaev, S.T.; Lebedev, V.I.; Zhukov, S.V. [National Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Balata, M.; Ioannucci, L.; Junker, M.; Laubenstein, M.; Macolino, C.; Nisi, S.; Pandola, L.; Zavarise, P. [LNGS, INFN Laboratori Nazionali del Gran Sasso, Assergi (Italy); Barabanov, I.; Bezrukov, L.; Gurentsov, V.; Inzhechik, L.V.; Kuzminov, V.V.; Lubsandorzhiev, B.; Yanovich, E. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Barnabe Heider, M. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Technische Universitaet Muenchen, Physik Department and Excellence Cluster Universe, Muenchen (Germany); Baudis, L.; Benato, G.; Ferella, A.; Guthikonda, K.K.; Tarka, M.; Walter, M. [Physik Institut der Universitaet Zuerich, Zuerich (Switzerland); Bauer, C.; Hampel, W.; Heisel, M.; Heusser, G.; Hofmann, W.; Kihm, T.; Kirsch, A.; Knoepfle, K.T.; Lindner, M.; Lubashevskiy, A.; Machado, A.A.; Maneschg, W.; Salathe, M.; Schreiner, J.; Schwingenheuer, B.; Simgen, H.; Smolnikov, A.; Strecker, H.; Wagner, V.; Wegmann, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Becerici-Schmidt, N.; Caldwell, A.; Cossavella, F.; Liao, H.Y.; Liu, X.; Majorovits, B.; O' Shaughnessy, C.; Schulz, O.; Volynets, O. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Bellotti, E.; Pessina, G. [Universita Milano Bicocca, Dipartimento di Fisica, Milano (Italy); INFN Milano Bicocca, Milano (Italy); Belogurov, S.; Kornoukhov, V.N. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Bettini, A.; Brugnera, R.; Garfagnini, A.; Hemmer, S.; Sada, C. [Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (Italy); INFN Padova, Padova (Italy); Brudanin, V.; Egorov, V.; Kochetov, O.; Nemchenok, I.; Rumyantseva, N.; Shevchik, E.; Zhitnikov, I.; Zinatulina, D. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Cattadori, C.; Gotti, C. [INFN Milano Bicocca, Milano (Italy); Chernogorov, A.; Demidova, E.V.; Kirpichnikov, I.V.; Vasenko, A.A. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Falkenstein, R.; Freund, K.; Grabmayr, P.; Hegai, A.; Jochum, J.; Schmitt, C. [Eberhard Karls Universitaet Tuebingen, Physikalisches Institut, Tuebingen (Germany); Frodyma, N.; Misiaszek, M.; Pelczar, K.; Wojcik, M.; Zuzel, G. [Jagiellonian University, Institute of Physics, Cracow (Poland); Gangapshev, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Gusev, K. [Joint Institute for Nuclear Research, Dubna (Russian Federation); National Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Technische Universitaet Muenchen, Physik Department and Excellence Cluster Universe, Muenchen (Germany); Hult, M.; Lutter, G. [Institute for Reference Materials and Measurements, Geel (Belgium); Klimenko, A. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Lippi, I.; Stanco, L.; Ur, C.A. [INFN Padova, Padova (Italy); Pullia, A.; Riboldi, S. [Universita degli Studi di Milano (IT); INFN Milano, Dipartimento di Fisica, Milano (IT); Shirchenko, M. [Joint Institute for Nuclear Research, Dubna (RU); National Research Centre ' ' Kurchatov Institute' ' , Moscow (RU); Sturm, K. von [Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (IT); INFN Padova, Padova (IT); Eberhard Karls Universitaet Tuebingen, Physikalisches Institut, Tuebingen (DE)

    2013-10-15

    The Gerda experiment located at the Laboratori Nazionali del Gran Sasso of INFN searches for neutrinoless double beta (0{nu}{beta}{beta}) decay of {sup 76}Ge using germanium diodes as source and detector. In Phase I of the experiment eight semi-coaxial and five BEGe type detectors have been deployed. The latter type is used in this field of research for the first time. All detectors are made from material with enriched {sup 76}Ge fraction. The experimental sensitivity can be improved by analyzing the pulse shape of the detector signals with the aim to reject background events. This paper documents the algorithms developed before the data of Phase I were unblinded. The double escape peak (DEP) and Compton edge events of 2.615 MeV {gamma} rays from {sup 208}Tl decays as well as two-neutrino double beta (2{nu}{beta}{beta}) decays of {sup 76}Ge are used as proxies for 0{nu}{beta}{beta} decay. For BEGe detectors the chosen selection is based on a single pulse shape parameter. It accepts 0.92{+-}0.02 of signal-like events while about 80 % of the background events at Q{sub {beta}{beta}} =2039 keV are rejected. For semi-coaxial detectors three analyses are developed. The one based on an artificial neural network is used for the search of 0 {nu}{beta}{beta} decay. It retains 90 % of DEP events and rejects about half of the events around Q{sub {beta}{beta}}. The 2 {nu}{beta}{beta} events have an efficiency of 0.85 {+-}0.02 and the one for 0 {nu}{beta}{beta} decays is estimated to be 0.90{sup +0.05}{sub -0.09}. A second analysis uses a likelihood approach trained on Compton edge events. The third approach uses two pulse shape parameters. The latter two methods confirm the classification of the neural network since about 90 % of the data events rejected by the neural network are also removed by both of them. In general, the selection efficiency extracted from DEP events agrees well with those determined from Compton edge events or from 2{nu}{beta}{beta} decays. (orig.)

  19. Plutonium metal vs. oxide determination with the pulse-shape-discrimination-capable plastic scintillator EJ-299-33

    Energy Technology Data Exchange (ETDEWEB)

    Pozzi, S.A., E-mail: pozzisa@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Bourne, M.M.; Dolan, J.L.; Polack, K.; Lawrence, C.; Flaska, M.; Clarke, S.D. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Tomanin, A.; Peerani, P. [European Commission Joint Research Centre, Institute for the Protection and Security of the Citizen Via Enrico Fermi, 2749 21027 Ispra VA (Italy)

    2014-12-11

    Neutron measurements can be used to distinguish plutonium in metal or oxide form, a capability that is of great interest in nuclear nonproliferation, treaty verification, and other applications. This paper describes measurements performed on well-characterized samples of plutonium oxide and plutonium metal using the pulse-shape-discrimination-capable plastic scintillator EJ-299-33. Results are compared to those obtained with a same-sized detector cell using the liquid scintillator EJ-309. The same optimized, digital pulse shape discrimination technique is applied to both detectors and the neutron pulse height distributions are compared. Results show that the EJ-299-33 plastics can be successfully used for plutonium measurements, where the gamma ray to neutron detection ratio is much higher than for typical radioactive sources. Results also show that EJ-299-33 detectors can be used to characterize plutonium samples, specifically to discriminate between plutonium metal and oxide.

  20. Digital Double-Pulse Holographic Interferometry for Vibration Analysis

    Directory of Open Access Journals (Sweden)

    H.J. Tiziani

    1996-01-01

    Full Text Available Different arrangements for double-pulsed holographic and speckle interferometry for vibration analysis will be described. Experimental results obtained with films (classical holographic interferometry and CCD cameras (digital holographic interferometry as storage materials are presented. In digital holography, two separate holograms of an object under test are recorded within a few microseconds using a CCD camera and are stored in a frame grabber. The phases of the two reconstructed wave fields are calculated from the complex amplitudes. The deformation is obtained from the phase difference. In the case of electronic speckle pattern interferometry (or image plane hologram, the phase can be calculated by using the sinusoid-fitting method. In the case of digital holographic interferometry, the phase is obtained by digital reconstruction of the complex amplitudes of the wave fronts. Using three directions of illumination and one direction of observation, all the information necessary for the reconstruction of the 3-dimensional deformation vector can be recorded at the same time. Applications of the method for measuring rotating objects are discussed where a derotator needs to be used.

  1. Pulse shape discrimination in helium-4 scintillation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, Ryan P., E-mail: rpkelley@ufl.edu; Enqvist, Andreas; Jordan, Kelly A.

    2016-09-11

    Three algorithms were investigated for discriminating between neutrons and gamma rays in a pressurized {sup 4}He gas fast neutron detector: charge comparison, weighted integration, and neutron-gamma model analysis (NGMA). For each algorithm, a comprehensive pulse shape discrimination study was conducted using time-of-flight measurements, receiver operator characteristic curves, figure of merit performance measures, and a comparison of performance between {sup 252}Cf and PuBe mixed neutron/gamma sources. The NGMA method was found to have the best overall performance by both the figure of merit and the receiver operator characteristic curve. The results also illustrated the high gamma rejection efficiency of these detectors, which is desirable in a variety of neutron monitoring applications.

  2. Pulse shape method for the Chimera silicon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Pagano, A.; Arena, N.; Cardella, G.; D' Andrea, M.; Filippo, E. de; Fichera, F.; Giudice, N.; Guardone, N.; Grimaldi, A.; Nicotra, D.; Papa, M.; Pirrone, S.; Politi, G.; Rapicavoli, C.; Rizza, G.; Russotto, P.; Sacca, G.; Urso, S.; Lanzano, G. [Catania Univ., INFN Catania and Dipartimento di Fisica e Astronomia (Italy); Alderighi, M.; Sechi, G. [INFN Milano and Istituto di Fisica Cosmica CNR, Milano (Italy); Amorini, F.; Anzalone, A.; Cali, C.; Campagna, V.; Cavallaro, S.; Di Stefano, A.; Giustolisi, F.; La Guidara, E.; Lanzalone, G.; Maiolino, C.; Porto, F.; Rizzo, F.; Salamone, S. [Catania Univ., INFN-LNS and Dipartimento di Fisica e Astronomia (Italy); Auditore, L.; Trifiro, A.; Trimarchi, M. [Messina Univ., INFN and Dipartimento di Fisica (Italy); Bassini, R.; Boiano, C.; Guazzoni, P.; Russo, S.; Sassi, M.; Zetta, L. [Milano Univ., INFN Milano and Dipartimento di Fisica (Italy); Blicharska, J.; Grzeszczuk, A. [Silesia Univ., Institute of Physics, Katowice (Poland); Chatterjee, M.B. [Saha Institute Of Nuclear Physics, Kolkata (India); Geraci, E.; Zipper, W. [Bologna Univ., INFN Bologna and Dipartimento di Fisica (Italy); Rosato, E.; Vigilante, M. [Napoli Univ., INFN and Dipartimento di Fisica (Italy); Schroder, W.U.; T-ke, J. [Rochester Univ., Dept. of Chemistry, Rochester, N.Y. (United States)

    2003-07-01

    Since January 2003, the 4{pi} CHIMERA (Charged Heavy Ions Mass and Energy Resolving Array) detector in its full configuration has successfully been operated at the 'Catania Laboratori Nazionali del Sud' (LNS) accelerator facility. The detector has been used with a variety of beams from the Superconducting Cyclotron in heavy-ion reaction studies at Fermi bombarding energies. Future experiments with a focus on isospin physics at Fermi energies, planned for both primary and less intense secondary particle beams, suggest the development of new and more versatile experimental particle identification methods. Recent achievements in implementing specific pulse shape particle identification methods for CHIMERA silicon detectors are reported. They suggest an upgrade of the present charge and mass identification capability of CHIMERA by a simple extension of the method. (authors)

  3. Processing of X-ray Microcalorimeter Data with Pulse Shape Variation using Principal Component Analysis

    CERN Document Server

    Yan, Daikang; Gades, Lisa; Jacobsen, Chris; Madden, Timothy; Miceli, Antonino

    2016-01-01

    We present a method using principal component analysis (PCA) to process x-ray pulses with severe shape variation where traditional optimal filter methods fail. We demonstrate that PCA is able to noise-filter and extract energy information from x-ray pulses despite their different shapes. We apply this method to a dataset from an x-ray thermal kinetic inductance detector which has severe pulse shape variation arising from position-dependent absorption.

  4. Note: All-digital pulse-shrinking time-to-digital converter with improved dynamic range

    Science.gov (United States)

    Chen, Chun-Chi; Hwang, Chorng-Sii; Lin, Yi; Chen, Guan-Hong

    2016-04-01

    This paper proposes an all-digital pulse-shrinking time-to-digital converter (TDC) using the offset error cancellation circuitry to widen its dynamic range and to improve its accuracy. Although the TDC based on a pulse-shrinking mechanism can achieve a sub-gate resolution without circuit complexity, it possesses an undesired offset error that results in a nonzero lower bound appeared in its dynamic range and then affects its accuracy. The proposed cancellation circuitry for eliminating the offset error consists of a time adder with a delay line and a time subtractor with an identical delay line. The experimental TDC is implemented on Xilinx field programmable gate arrays and it also functions successfully in improving its dynamic range.

  5. Note: All-digital pulse-shrinking time-to-digital converter with improved dynamic range.

    Science.gov (United States)

    Chen, Chun-Chi; Hwang, Chorng-Sii; Lin, Yi; Chen, Guan-Hong

    2016-04-01

    This paper proposes an all-digital pulse-shrinking time-to-digital converter (TDC) using the offset error cancellation circuitry to widen its dynamic range and to improve its accuracy. Although the TDC based on a pulse-shrinking mechanism can achieve a sub-gate resolution without circuit complexity, it possesses an undesired offset error that results in a nonzero lower bound appeared in its dynamic range and then affects its accuracy. The proposed cancellation circuitry for eliminating the offset error consists of a time adder with a delay line and a time subtractor with an identical delay line. The experimental TDC is implemented on Xilinx field programmable gate arrays and it also functions successfully in improving its dynamic range.

  6. Advantages of solitonic shape pulses for full-optical wireless communication links

    Institute of Scientific and Technical Information of China (English)

    José María Garrido Balsells; Antonio Jurado-Navas; Miguel Castillo-Vázquez; Ana Belén Moreno-Garrido; Antonio Puerta-Notario

    2012-01-01

    We propose the use of a power pulse shape of the widely known optical soliton,corresponding to the hyperbolic secant square function,for both conventional atmospheric optical communication systems and,especially,for new full-optical wireless communications.We analyze the performance of the proposed pulse in terms of peak-to-average optical power ratio (PAOPR) and bit error rate (BER).During the analysis,we compare the proposed pulse shape against conventional rectangular and Gaussian pulse shapes with reduced duty cycle.Results show the noticeable superiority of the proposed pulse for atmospheric optical links.

  7. Inter-carrier Interference Mitigation in OFDM System Using a New Pulse Shaping Approach

    Directory of Open Access Journals (Sweden)

    Nor Adibah Ibrahim

    2014-12-01

    Full Text Available In this paper, we suggest a new pulse shaping method namely scale alpha for orthogonal frequency-division multiplexing (OFDM system. The proposed pulse shape is designed and simulated using Matlab software. Results and discussions are made to analyze the performance of the new pulse shape, particularly regarding two parameters that are inter-carrier interference (ICI power reduction, and eye diagrams. It is shown that the new pulse is better in ICI power reduction performance than Franks, raised cosine, and double-jump pulses.

  8. Pulsed Laser Interactions with Space Debris: Target Shape Effects

    CERN Document Server

    Liedahl, D A; Libby, S B; Nikolaev, S; Phipps, C R

    2013-01-01

    Among the approaches to the proposed mitigation and remediation of the space debris problem is the de-orbiting of objects in low Earth orbit through irradiation by ground-based high-intensity pulsed lasers. Laser ablation of a thin surface layer causes target recoil, resulting in the depletion of orbital angular momentum and accelerated atmospheric re-entry. However, both the magnitude and direction of the recoil are shape dependent, a feature of the laser-based remediation concept that has received little attention. Since the development of a predictive capability is desirable, we have investigated the dynamical response to ablation of objects comprising a variety of shapes. We derive and demonstrate a simple analytical technique for calculating the ablation-driven transfer of linear momentum, emphasizing cases for which the recoil is not exclusively parallel to the incident beam. For the purposes of comparison and contrast, we examine one case of momentum transfer in the low-intensity regime, where photon p...

  9. Implementation of a real-time adaptive digital shaping for nuclear spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Regadío, Alberto, E-mail: aregadio@srg.aut.uah.es [Department of Computer Engineering, Space Research Group, Universidad de Alcalá, 28805 Alcalá de Henares (Spain); Electronic Technology Area, Instituto Nacional de Técnica Aeroespacial, 28850 Torrejón de Ardoz (Spain); Sánchez-Prieto, Sebastián, E-mail: ssanchez@srg.aut.uah.es [Department of Computer Engineering, Space Research Group, Universidad de Alcalá, 28805 Alcalá de Henares (Spain); Prieto, Manuel, E-mail: mprieto@srg.aut.uah.es [Department of Computer Engineering, Space Research Group, Universidad de Alcalá, 28805 Alcalá de Henares (Spain); Tabero, Jesús, E-mail: taberogj@inta.es [Electronic Technology Area, Instituto Nacional de Técnica Aeroespacial, 28850 Torrejón de Ardoz (Spain)

    2014-01-21

    This paper presents the structure, design and implementation of a new adaptive digital shaper for processing the pulses generated in nuclear particle detectors. The proposed adaptive algorithm has the capacity to automatically adjust the coefficients for shaping an input signal with a desired profile in real-time. Typical shapers such as triangular, trapezoidal or cusp-like ones can be generated, but more exotic unipolar shaping could also be performed. A practical prototype was designed, implemented and tested in a Field Programmable Gate Array (FPGA). Particular attention was paid to the amount of internal FPGA resources required and to the sampling rate, making the design as simple as possible in order to minimize power consumption. Lastly, its performance and capabilities were measured using simulations and a real benchmark.

  10. Pulse shaping method to compensate for antenna distortion in ultra-wideband communications

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In the ultra-wideband (UWB) communication systems, a critical spectral mask is released to restrict the allowable interference to other wireless devices by the Federal Communications Commission (FCC), and then some pulse shaping methods have been presented to fulfil the mask. However, most pulse shaping methods do not consider the antenna distortion which cannot be neglected in the UWB communication systems compared with the conventional systems. To this end, an orthogonal wavelet based pulse shaping method is proposed in this paper to integrate compensation of antenna distortion into pulse shaping. Simulation results show that the novel pulse shaping method can be used to achieve compensation for antenna distortion, optimization of transmission power spectrum, and simplification of the algorithm, as well as simple implementation of the pulse generator.

  11. Evolution of hole shape and size during short and ultrashort pulse laser deep drilling.

    Science.gov (United States)

    Döring, Sven; Szilagyi, John; Richter, Sören; Zimmermann, Felix; Richardson, Martin; Tünnermann, Andreas; Nolte, Stefan

    2012-11-19

    A detailed study of the influence of the pulse duration, from the femtosecond to the nanosecond regime, on the evolution of the hole shape and depth during percussion drilling in silicon is presented. Real-time backlight imaging of the hole development is obtained for holes up to 2 mm deep with aspect ratios extending to 25:1. For low pulse energies, the hole-shape and drilling characteristics are similar for femtosecond, picoseconds and nanosecond regimes. At higher pulse energies, ns-pulses exhibit slower average drilling rates but eventually reach greater final depths. The shape of these holes is however dominated by branching and large internal cavities. For ps-pulses, a cylindrical shape is maintained with frequent small bulges on the side-walls. In contrast, fs-pulses cause only a limited number of imperfections on a tapered hole shape.

  12. Alpha–gamma pulse-shape discrimination in Gd{sub 3}Al{sub 2}Ga{sub 3}O{sub 12} (GAGG):Ce{sup 3+} crystal scintillator using shape indicator

    Energy Technology Data Exchange (ETDEWEB)

    Tamagawa, Yoichi, E-mail: tamagawa@u-fukui.ac.jp [Graduate school of Engineering, University of Fukui, Fukui 910-8507 (Japan); Inukai, Yuji; Ogawa, Izumi [Graduate school of Engineering, University of Fukui, Fukui 910-8507 (Japan); Kobayashi, Masaaki [IPNS, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan)

    2015-09-21

    The pulse-shape discrimination (PSD) in a GAGG single-crystal scintillator was studied by using a shape indicator (SI) parameter of the optimal digital filter method. SI is one of the most useful PSD methods that use typical pulse shapes. Excellent discrimination between 0.662 MeV γ-rays and 5.48 MeV α-rays was achieved. For a cut at SI=0.0056, 99.95% of the γ-rays and only 0.22% of the α-rays were retained. Selection of background events (γ and α) in the GAGG scintillator was achieved by using the PSD method.

  13. High-sensitive Optical Pulse-Shape Characterization using a Beating-Contrast-Measurement Technique

    CERN Document Server

    Roncin, Vincent; Millaud, Audrey; Cramer, Romain; Jaouën, Yves; Simon, Jean-Claude

    2014-01-01

    Ultrahigh-speed optical transmission technology, such as optical time domain multiplexing or optical signal processing is a key point for increasing the communication capacity. The system performances are strongly related to pulse properties. We present an original method dedicated to short pulse-shape characterization with high repetition rate using standard optical telecommunications equipments. Its principle is based on temporal measurement of the contrast produced by the beating of two delayed optical pulses in a high bandwidth photo detector. This technique returns firstly reliable information on the pulse-shape, such as pulse width, shape and pedestal. Simulation and experimental results evaluate the high-sensitivity and the high-resolution of the technique allowing the measurement of pulse extinction ratio up to 20 dB with typical timing resolution of about 100 fs. The compatibility of the technique with high repetition rate pulse measurement offers an efficient tool for short pulse analysis.

  14. Laser beam welding of titanium nitride coated titanium using pulse-shaping

    Directory of Open Access Journals (Sweden)

    Milton Sergio Fernandes de Lima

    2005-09-01

    Full Text Available A new welding method which allows the assembly of two titanium nitride coated titanium parts is proposed. The welding procedure utilizes the possibility for pulse-shaping in order to change the energy distribution profile during the laser pulse. The pulse-shaping is composed of three elements: a a short high power pulse for partial ablation at the surface; b a long pulse for thermal penetration; and c a quenching slope for enhanced weldability. The combination of these three elements produces crack-free welds. The weld microstructure is changed in comparison to normal welding, i.e. with a rectangular pulse, as the nitrogen and the microhardness are more homogenously distributed in the weld under pulse-shaping conditions. This laser pulse dissolves the TiN layer and allows nitrogen to diffuse into the melt pool, also contributing to an enhanced weldability by providing suitable thermal conditions.

  15. Progresses in the pulse shape identification with silicon detectors within the FAZIA Collaboration

    Energy Technology Data Exchange (ETDEWEB)

    Bardelli, L., E-mail: bardelli@fi.infn.it [Universita degli Studi di Firenze (Italy); I.N.F.N Sezione di Firenze (Italy); Bini, M. [Universita degli Studi di Firenze (Italy); I.N.F.N Sezione di Firenze (Italy); Casini, G. [I.N.F.N Sezione di Firenze (Italy); Edelbruck, P. [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay cedex (France); Pasquali, G.; Poggi, G. [Universita degli Studi di Firenze (Italy); I.N.F.N Sezione di Firenze (Italy); Barlini, S. [LPC Caen, ENSICAEN, Universite de Caen, CNRS/IN2P3, Caen (France); Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay cedex (France); Berjillos, R. [Departamento de Fisica Aplicada, Universidad de Huelva, E-21071 Huelva (Spain); Borderie, B. [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay cedex (France); Bougault, R. [LPC Caen, ENSICAEN, Universite de Caen, CNRS/IN2P3, Caen (France); Bruno, M. [Universita degli Studi di Bologna (Italy); I.N.F.N. Sezione di Bologna (Italy); Carboni, S. [Universita degli Studi di Firenze (Italy); I.N.F.N Sezione di Firenze (Italy); Chbihi, A. [Grand Accelerateur National d' Ions Lourds, Bd Henri Becquerel, BP 55027-14076 CAEN Cedex 05 (France); D' Agostino, M. [Universita degli Studi di Bologna (Italy); I.N.F.N. Sezione di Bologna (Italy); Duenas, J.A. [Departamento de Fisica Aplicada, Universidad de Huelva, E-21071 Huelva (Spain); Gautier, J.M. [LPC Caen, ENSICAEN, Universite de Caen, CNRS/IN2P3, Caen (France); Gramegna, F. [I.N.F.N. Laboratori Nazionali di Legnaro (Italy); Huss, C. [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay cedex (France); Kordyasz, A.J. [Heavy Ion Laboratory, Warsaw University, Pasteura 5a, 02-093 Warsaw (Poland); Kozik, T. [Jagiellonian University, Institute of Physics, Reymonta 4, 30-059 Krakow (Poland); and others

    2011-10-21

    In the last few years the FAZIA collaboration has been investigating the properties of silicon detectors - in particular the crystal orientation and resistivity non-uniformity - in order to better pin down the detector characteristics that influence their performances for particle identification using {Delta}E-E and Pulse Shape Analysis (PSA) techniques. In this paper we present the first particle identification results obtained with detectors selected for good resistivity uniformity and using a 'non-channeled' configuration. A new digital electronics was also designed for the R and D phase of FAZIA and was tested under beam for the first time. A quantitative procedure to measure the observed performances is applied in order to quantify the particle identification thresholds. Particle identification thresholds of {approx}2.5AMeV for Z{approx}3-10 have been reached with the studied reaction.

  16. Progresses in the pulse shape identification with silicon detectors within the FAZIA Collaboration

    Science.gov (United States)

    Bardelli, L.; Bini, M.; Casini, G.; Edelbruck, P.; Pasquali, G.; Poggi, G.; Barlini, S.; Berjillos, R.; Borderie, B.; Bougault, R.; Bruno, M.; Carboni, S.; Chbihi, A.; D'Agostino, M.; Dueñas, J. A.; Gautier, J. M.; Gramegna, F.; Huss, C.; Kordyasz, A. J.; Kozik, T.; Kravchuk, V. L.; Le Neindre, N.; Lopez, O.; Martel, I.; Morelli, L.; Ordine, A.; Rivet, M. F.; Rosato, E.; Scarlini, E.; Spadaccini, G.; Tobia, G.; Vigilante, M.; Wanlin, E.; Fazia Collaboration

    2011-10-01

    In the last few years the FAZIA [1] collaboration has been investigating the properties of silicon detectors - in particular the crystal orientation and resistivity non-uniformity - in order to better pin down the detector characteristics that influence their performances for particle identification using ΔE-E and Pulse Shape Analysis (PSA) techniques. In this paper we present the first particle identification results obtained with detectors selected for good resistivity uniformity and using a "non-channeled" configuration. A new digital electronics was also designed for the R&D phase of FAZIA and was tested under beam for the first time. A quantitative procedure to measure the observed performances is applied in order to quantify the particle identification thresholds. Particle identification thresholds of ˜2.5 AMeV for Z˜3-10 have been reached with the studied reaction.

  17. A template for describing intrinsic GRB pulse shapes

    CERN Document Server

    Hakkila, Jon; Wolpert, Robert L; Broadbent, Mary E; Preece, Robert D

    2013-01-01

    A preliminary study of a set of well-isolated pulses in GRB light curves indicates that simple pulse models, with smooth and monotonic pulse rise and decay regions, are inadequate. Examining the residuals of fits of pulses to such models suggests the following patterns of departure from the smooth pulse model of Norris et al. (2005): A Precursor Shelf occurs prior to or concurrent with the exponential Rapid Rise. The pulse reaches maximum intensity at the Peak Plateau, then undergoes a Rapid Decay. The decay changes into an Extended Tail. Pulses are almost universally characterized by hard-to-soft evolution, arguing that the new pulse features reflect a single physical phenomenon, rather than artifacts of pulse overlap.

  18. Laser-driven proton acceleration enhancement by the optimized intense short laser pulse shape

    Science.gov (United States)

    Souri, S.; Amrollahi, R.; Sadighi-Bonabi, R.

    2017-05-01

    Interactions of two distinct shapes of the pulses namely positive/negative chirped pulse and fast/slow rising-edge pulse with plasma are studied using particle-in-cell simulation. It is found that, for a pulse duration of 34 fs and intensity a0 = 12, proton acceleration could be enhanced by asymmetric pulses with either pulse envelope or pulse frequency modification. The number of accelerated protons, as well as the proton energy cut-off, is increased by asymmetric pulses. In this work, for positive chirped pulse, electrostatic field at the rear side of the target is improved by about 30%, which in turns leads to an increase in the proton energy cut-off more than 40%. Moreover, in contrary to the fast pulses, the slow one could enhance the proton energy cut-off up to 65% for 34 fs pulse with 20 fs rising-edge.

  19. Temporal shaping of third-harmonic pulses on the Nova laser system

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, J.K.; Speck, D.R.; Bibeau, C.; Burkhart, S.C.; Henesian, M.A.; Laumann, C.W.; Weiland, T.L.; Wilcox, R.B. (Lawrence Livermore National Laboratory, P.O. Box 5508 L-493, Livermore, California 94550 (United States))

    1992-08-20

    We demonstrate temporal shaping of 0.35-{mu}m- wavelength pulses produced by a third-harmonic conversion of the output from the Nova Nd:phosphate glass-laser amplifier system for use in inertial confinement fusion experiments. We describe the computer models used to calculate the pulse shape that is required as the input to the amplifier system, the experimental apparatus used to produce these pulses, and the high-power 0.35-{mu}m shaped pulses produced in recent experiments.

  20. Effect of crash pulse shape on seat stroke requirements for limiting loads on occupants of aircraft

    Science.gov (United States)

    Carden, Huey D.

    1992-01-01

    An analytical study was made to provide comparative information on various crash pulse shapes that potentially could be used to test seats under conditions included in Federal Regulations Part 23 Paragraph 23.562(b)(1) for dynamic testing of general aviation seats, show the effects that crash pulse shape can have on the seat stroke requirements necessary to maintain a specified limit loading on the seat/occupant during crash pulse loadings, compare results from certain analytical model pulses with approximations of actual crash pulses, and compare analytical seat results with experimental airplace crash data. Structural and seat/occupant displacement equations in terms of the maximum deceleration, velocity change, limit seat pan load, and pulse time for five potentially useful pulse shapes were derived; from these, analytical seat stroke data were obtained for conditions as specified in Federal Regulations Part 23 Paragraph 23.562(b)(1) for dynamic testing of general aviation seats.

  1. Annular Pulse Shaping Technique for Large-Diameter Kolsky Bar Experiments on Concrete

    Science.gov (United States)

    2014-10-01

    lt ag e (V ) Time (microsecond) Fig. 5 Linear incident wave generated using an annular copper pulse shaper (O.D. = 25.4 mm, I.D. = 14.4 mm). Note that...AFRL-RW-EG-TP-2014-005 Annular Pulse Shaping Technique for Large- Diameter Kolsky Bar Experiments on Concrete...NUMBER (Include area code) 13-6-2014 Technical Publication October 2012 - February 2014 ANNULAR PULSE SHAPING TECHNIQUE FOR LARGE-DIAMETER KOLSKY BAR

  2. Digital holographic interferometry as a tool to obtain shapes

    Science.gov (United States)

    Uribe López, Ubaldo; Hernández-Montes, María. del Socorro; Muñoz-Solís, Silvino

    2015-08-01

    This work describes a new method to obtain shapes on surfaces based on digital holographic interferometry (DHI). Research has been reported with different methods, such as fringe projection. DHI, being a full-field technique, decreases the number of images to capture and the processing time, besides having a high resolution. Our proposed method consists in obtaining the shape of the object and a reference plane using an out-of-plane interferometer. The phase difference of the recorded holograms is achieved by means of the Fourier transform method. This resulting phase has a tilt produced by the angle of the object beam relative to the optical axis, which is removed by subtracting the phase difference from the reference plane. The method was tested in two cylinders, one with dimensions of 17.5x23.4mm reconstructed with a height sensitivity of 4.1mm, and another with two levels: one half with dimensions of 16.08x12.75mm, and the other half of 19.07x12.75mm; the result was a successfully reconstructed shape, with a height sensitivity of 2.7mm.

  3. Ultrafast temporal pulse shaping via phase-sensitive three-wave mixing.

    Science.gov (United States)

    Yin, Y C; French, D; Jovanovic, I

    2010-08-16

    It is well-known that the process of optical parametric amplification (OPA) can be sensitive to the phases of the incident waves. In OPA realized by three-wave mixing, injection of all three waves into the same mode with appropriate phase relationship results in amplification of the signal phase, with an associated deamplification of the signal energy. Prospects for the use of this technique in the temporal domain for shaping ultrashort laser pulses are analyzed using a numerical model. Several representative pulse shaping capabilities of this technique are identified, which can significantly augment the performance of common passive pulse shaping methods operating in the Fourier domain. It is found that the use of phase-sensitive OPA shows a potential for significant compression of approximately 100 fs pulses, steepening of the rise time of ultrashort pulses, and production of pulse doublets and pulse trains. It is also shown that the group velocity mismatch can assist the shaping process. Such pulse shaping capabilities are found to be within reach of this technique in common nonlinear optical crystals pumped by pulses available from compact femtosecond chirped-pulse amplification laser systems.

  4. Digital control of pulsed gas metal arc welding inverter using TMS320LF2407A

    Institute of Scientific and Technical Information of China (English)

    Wu Kaiyuan; Huang Shisheng; Li Xinglin; Wu Shuifeng

    2008-01-01

    A digital control of pulsed gas metal arc welding inverter was proposed. A control system consisting of analogue parts was replaced with a new digital control implemented in a TMS320LF2407A DSP chip. The design and constructional features of the whole digital control were presented. The resources of the DSP chip were efficiently utilized and the circuits are very concise, which can enhance the stability and reliability of welding inverter. Experimental results demonstrate that the developed digital control has the ability to accomplish the excellent pulsed gas metal arc welding process and the merits of the developed digital control are stable welding process, little spatter and perfect weld appearance.

  5. Propagation of subcycle pulses in a two-level medium: Area-theorem breakdown and pulse shape

    CERN Document Server

    Novitsky, Denis

    2013-01-01

    We solve the problem of ultrashort pulse propagation in a two-level medium beyond the rotating-wave (RWA) and slowly-varying-envelope approximations. The method of solution is based on the Maxwell--Bloch equations represented in the form that allows one to switch between RWA and general (non-RWA) cases in the framework of a single numerical algorithm. Using this method, the effect of a subcycle pulse (containing less than a single period of field oscillations) on the two-level medium was analyzed. It is shown that for such short pulses, the clear breakdown of the area theorem occurs for the pulses of large enough area. Moreover, deviations from the area theorem appear to be strongly dependent on the pulse shape that cannot be observed for longer few-cycle pulses.

  6. Multi-shape active composites by 3D printing of digital shape memory polymers.

    Science.gov (United States)

    Wu, Jiangtao; Yuan, Chao; Ding, Zhen; Isakov, Michael; Mao, Yiqi; Wang, Tiejun; Dunn, Martin L; Qi, H Jerry

    2016-04-13

    Recent research using 3D printing to create active structures has added an exciting new dimension to 3D printing technology. After being printed, these active, often composite, materials can change their shape over time; this has been termed as 4D printing. In this paper, we demonstrate the design and manufacture of active composites that can take multiple shapes, depending on the environmental temperature. This is achieved by 3D printing layered composite structures with multiple families of shape memory polymer (SMP) fibers - digital SMPs - with different glass transition temperatures (Tg) to control the transformation of the structure. After a simple single-step thermomechanical programming process, the fiber families can be sequentially activated to bend when the temperature is increased. By tuning the volume fraction of the fibers, bending deformation can be controlled. We develop a theoretical model to predict the deformation behavior for better understanding the phenomena and aiding the design. We also design and print several flat 2D structures that can be programmed to fold and open themselves when subjected to heat. With the advantages of an easy fabrication process and the controllable multi-shape memory effect, the printed SMP composites have a great potential in 4D printing applications.

  7. Multi-shape active composites by 3D printing of digital shape memory polymers

    Science.gov (United States)

    Wu, Jiangtao; Yuan, Chao; Ding, Zhen; Isakov, Michael; Mao, Yiqi; Wang, Tiejun; Dunn, Martin L.; Qi, H. Jerry

    2016-04-01

    Recent research using 3D printing to create active structures has added an exciting new dimension to 3D printing technology. After being printed, these active, often composite, materials can change their shape over time; this has been termed as 4D printing. In this paper, we demonstrate the design and manufacture of active composites that can take multiple shapes, depending on the environmental temperature. This is achieved by 3D printing layered composite structures with multiple families of shape memory polymer (SMP) fibers - digital SMPs - with different glass transition temperatures (Tg) to control the transformation of the structure. After a simple single-step thermomechanical programming process, the fiber families can be sequentially activated to bend when the temperature is increased. By tuning the volume fraction of the fibers, bending deformation can be controlled. We develop a theoretical model to predict the deformation behavior for better understanding the phenomena and aiding the design. We also design and print several flat 2D structures that can be programmed to fold and open themselves when subjected to heat. With the advantages of an easy fabrication process and the controllable multi-shape memory effect, the printed SMP composites have a great potential in 4D printing applications.

  8. 3D visualization using pulsed and CW digital holographic tomography techniques (Invited Paper)

    Institute of Scientific and Technical Information of China (English)

    G. Nehmetallah; P. P. Banerjee; D. Ferree; R. Kephart; S. Praharaj

    2011-01-01

    We outline the use of digital holographic tomography to determine the three-dimensional (3D) shapes of falling and static objects, such as lenslets and water droplets. Reconstruction of digitally recorded inline holograms is performed using multiplicative and Radon transform techniques to reveal the exact 3D shapes of the objects.%We outline the use of digital holographic tomography to determine the three-dimensional (3D) shapes of falling and static objects,such as lenslets and water droplets.Reconstruction of digitally recorded inline holograms is performed using multiplicative and Radon transform techniques to reveal the exact 3D shapes of the objects.

  9. A Novel Pulse Shaping for UWB Impulse Radio IEEE 802.15.4a Communications Systems

    Directory of Open Access Journals (Sweden)

    BARRAJ Imen

    2014-05-01

    Full Text Available This paper presents a novel pulse shape which we call modified triangular pulse (MTri for Impulse Radio-Ultra Wide Band (IR-UWB IEEE 802.15.4a systems. The MTri pulse and UWB shapes previously proposed for low power IR-UWB transceivers topologies are studied and compared. The performance measures considered are compliance with required spectral emission constrains, Mask Loss (ML power and pulse energy. Our theoretical and simulations results show the advantages of the MTri pulse over studies UWB pulses. It presents the lower ML power about 0.45dB and the higher pulse energy of 0.45nJ/p.

  10. Analytical optimal pulse shapes obtained with the aid of genetic algorithms

    Science.gov (United States)

    Guerrero, Rubén D.; Arango, Carlos A.; Reyes, Andrés

    2015-09-01

    We propose a methodology to design optimal pulses for achieving quantum optimal control on molecular systems. Our approach constrains pulse shapes to linear combinations of a fixed number of experimentally relevant pulse functions. Quantum optimal control is obtained by maximizing a multi-target fitness function using genetic algorithms. As a first application of the methodology, we generated an optimal pulse that successfully maximized the yield on a selected dissociation channel of a diatomic molecule. Our pulse is obtained as a linear combination of linearly chirped pulse functions. Data recorded along the evolution of the genetic algorithm contained important information regarding the interplay between radiative and diabatic processes. We performed a principal component analysis on these data to retrieve the most relevant processes along the optimal path. Our proposed methodology could be useful for performing quantum optimal control on more complex systems by employing a wider variety of pulse shape functions.

  11. Analytical optimal pulse shapes obtained with the aid of genetic algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero, Rubén D., E-mail: rdguerrerom@unal.edu.co [Department of Physics, Universidad Nacional de Colombia, Bogota (Colombia); Arango, Carlos A. [Department of Chemical Sciences, Universidad Icesi, Cali (Colombia); Reyes, Andrés [Department of Chemistry, Universidad Nacional de Colombia, Bogota (Colombia)

    2015-09-28

    We propose a methodology to design optimal pulses for achieving quantum optimal control on molecular systems. Our approach constrains pulse shapes to linear combinations of a fixed number of experimentally relevant pulse functions. Quantum optimal control is obtained by maximizing a multi-target fitness function using genetic algorithms. As a first application of the methodology, we generated an optimal pulse that successfully maximized the yield on a selected dissociation channel of a diatomic molecule. Our pulse is obtained as a linear combination of linearly chirped pulse functions. Data recorded along the evolution of the genetic algorithm contained important information regarding the interplay between radiative and diabatic processes. We performed a principal component analysis on these data to retrieve the most relevant processes along the optimal path. Our proposed methodology could be useful for performing quantum optimal control on more complex systems by employing a wider variety of pulse shape functions.

  12. Quantum gate operations using midinfrared binary shaped pulses on the rovibrational states of carbon monoxide.

    Science.gov (United States)

    Zaari, Ryan R; Brown, Alex

    2010-01-07

    Frequency domain shaped binary laser pulses were optimized to perform 2 qubit quantum gate operations in (12)C(16)O. The qubit rovibrational state representation was chosen so that all gate operations consisted of one-photon transitions. The amplitude and phase varied binary pulses were determined using a genetic algorithm optimization routine. Binary pulses have two possible amplitudes, 0 or 1, and two phases, 0 or pi, for each frequency component of the pulse. Binary pulses are the simplest to shape experimentally and provide a minimum fidelity limit for amplitude and phase shaped pulses. With the current choice of qubit representation and using optimized binary pulses, fidelities of 0.80 and as high as 0.97 were achieved for the controlled-NOT and alternative controlled-NOT quantum gates. This indicates that with a judicious choice of qubits, most of the required control can be obtained with a binary pulse. Limited control was observed for 2 qubit NOT and Hadamard gates due to the need to control multiple excitations. The current choice of qubit representation produces pulses with decreased energies and superior fidelities when compared with rovibrational qubit representations consisting of two-photon transitions. The choice of input pulse energy is important and applying pulses of increased energy does not necessarily lead to a better fidelity.

  13. BEBEtr and BUBI: J-compensated concurrent shaped pulses for 1H-13C experiments

    Science.gov (United States)

    Ehni, Sebastian; Luy, Burkhard

    2013-07-01

    Shaped pulses designed for broadband excitation, inversion and refocusing are important tools in modern NMR spectroscopy to achieve robust pulse sequences especially in heteronuclear correlation experiments. A large variety of mostly computer-optimized pulse shapes exist for different desired bandwidths, available rf-field strengths, and tolerance to B1-inhomogeneity. They are usually derived for a single spin 1/2, neglecting evolution due to J-couplings. While pulses with constant resulting phase are selfcompensated for heteronuclear coupling evolution as long as they are applied exclusively on a single nucleus, the situation changes for concurrently applied pulse shapes. Using the example of a 1H,13C two spin system, two J-compensated pulse pairs for the application in INEPT-type transfer elements were optimized: a point-to-point pulse sandwich called BEBEtr, consisting of a broadband excitation and time-reversed excitation pulse, and a combined universal rotation and point-to-point pulse pair called BUBI, which acts as a refocusing pulse on 1H and a corresponding inversion pulse on 13C. After a derivation of quality factors and optimization protocols, a theoretical and experimental comparison with conventionally derived BEBOP, BIBOP, and BURBOP-180° pulses is given. While the overall transfer efficiency of a single pulse pair is only reduced by approximately 0.1%, resulting transfer to undesired coherences is reduced by several percent. In experiments this can lead to undesired phase distortions for pairs of uncompensated pulse shapes and even differences in signal intensities of 5-10% in HSQC and up to 68% in more complex COB-HSQC experiments.

  14. Elongation of plasma channel generated by temporally shaped femtosecond laser pulse

    Science.gov (United States)

    Chen, Anmin; Li, Suyu; Qi, Hongxia; Jiang, Yuanfei; Hu, Zhan; Huang, Xuri; Jin, Mingxing

    2017-01-01

    Temporally shaped femtosecond laser pulse is used to generate the air plasma channel. The length of plasma channel is optimized by a genetic algorithm. Compared with the transform-limited pulse, the temporally shaped femtosecond laser produced by the spatial light modulator with the genetic algorithm can lead to a significant increase in length and brightness of plasma channel in atmosphere. In particular, the length of the plasma channel produced by the optimized shaped pulse can be extended by 50%. This method can be especially advantageous in the context of femtosecond laser-induced plasma channel.

  15. Extremely Nonlinear Optics Using Shaped Pulses Spectrally Broadened in an Argon- or Sulfur Hexafluoride-Filled Hollow-Core Fiber

    OpenAIRE

    Andreas Hoffmann; Michael Zürch; Christian Spielmann

    2015-01-01

    In this contribution we present a comparison of the performance of spectrally broadened ultrashort pulses using a hollow-core fiber either filled with argon or sulfur hexafluoride (SF6) for demanding pulse-shaping experiments. The benefits of both gases for pulse-shaping are studied in the highly nonlinear process of high-harmonic generation. In this setup, temporally shaping the driving laser pulse leads to spectrally shaping of the output extreme ultraviolet (XUV) spectrum, where total yie...

  16. Temporal Shaping of High Peak Power Pulse Trains from a Burst-Mode Laser System

    Directory of Open Access Journals (Sweden)

    Jörg Körner

    2015-12-01

    Full Text Available It has been shown in the past that pulsed laser systems operating in the so-called “burst mode” are a beneficial approach to generate high peak power laser pulses at high repetition rates suitable for various applications. So far, most high-energy burst-mode laser systems put great effort into generating a homogeneous energy distribution across the burst duration, e.g., by shaping the pump pulse. In this work, we present a new shaping technique, which is able to produce arbitrary energy distributions within the burst by pre-shaping the seed pulse burst with a Pockels cell. Furthermore, this technique allows for the precompensation of any static modulations across the burst, which may be introduced during the subsequent amplification process. Therefore, a pulse burst with a uniform energy distribution can also be generated. The method is tested with an ultra-short pulse burst mode laser amplifier system producing bursts of a 1 ms duration with a pulse repetition rate of 1 MHz and a maximum output power of 800 W during the burst. Furthermore, a method to predict the influence of the amplifier on a non-uniformly shaped burst is presented and successfully tested to produce a pre-defined pulse shape after amplification.

  17. Laser ablation of borosilicate glass with high power shaped UV nanosecond laser pulses

    Science.gov (United States)

    von Witzendorff, Philipp; Bordin, Andrea; Suttmann, Oliver; Patel, Rajesh S.; Bovatsek, James; Overmeyer, Ludger

    2016-03-01

    The application of thin borosilicate glass as interposer material requires methods for separation and drilling of this material. Laser processing with short and ultra-short laser pulses have proven to enable high quality cuts by either direct ablation or internal glass modification and cleavage. A recently developed high power UV nanosecond laser source allows for pulse shaping of individual laser pulses. Thus, the pulse duration, pulse bursts and the repetition rate can be set individually at a maximum output power of up to 60 W. This opens a completely new process window, which could not be entered with conventional Q-switched pulsed laser sources. In this study, the novel pulsed UV laser system was used to study the laser ablation process on 400 μm thin borosilicate glass at different pulse durations ranging from 2 - 10 ns and a pulse burst with two 10 ns laser pulses with a separation of 10 ns. Single line scan experiments were performed to correlate the process parameters and the laser pulse shape with the ablation depth and cutting edge chipping. Increasing the pulse duration within the single pulse experiments from 2 ns to longer pulse durations led to a moderate increase in ablation depth and a significant increase in chipping. The highest material removal was achieved with the 2x10 ns pulse burst. Experimental data also suggest that chipping could be reduced, while maintaining a high ablation depth by selecting an adequate pulse overlap. We also demonstrate that real-time combination of different pulse patterns during drilling a thin borosilicate glass produced holes with low overall chipping at a high throughput rate.

  18. ASIC Design and Implementation for Digital Pulse Compression Chip

    Institute of Scientific and Technical Information of China (English)

    高俊峰; 韩月秋; 王巍

    2004-01-01

    A novel ASIC design of changeable-point digital pulse compression (DPC) chip is presented. System hardware resource is reduced to one third of the traditional design method through operations sharing hardware, i.e. let FFT, complex multiplication and IFFT be fulfilled with the same hardware structure. Block-floating-point scaling is used to enhance the dynamic range and computation accuracy. This design applies parallel pipeline structure and the radix-4 butterfly operation to improve the processing speed. In addition, a triple-memory-space(TMS) configuration is used that allows input, computation and output operations to be overlapped, so that the dual-butterfly unit is never left in an idle state waiting for I/O operation. The whole design is implemented with only one chip of XC2V500-5 FPGA. It can implement 1 024-point DPC within 91.6 μs.The output data is converted to floating-point formation to achieve seamless interface with TMS320C6701. The validity of the design is verified by simulation and measurement results.

  19. Optimally shaped narrowband picosecond pulses for femtosecond stimulated Raman spectroscopy.

    Science.gov (United States)

    Hoffman, David P; Valley, David; Ellis, Scott R; Creelman, Mark; Mathies, Richard A

    2013-09-09

    A comparison between a Fabry-Pérot etalon filter and a conventional grating filter for producing the picosecond (ps) Raman pump pulses for femtosecond stimulated Raman spectroscopy (FSRS) is presented. It is shown that for pulses of equal energy the etalon filter produces Raman signals twice as large as that of the grating filter while suppressing the electronically resonant background signal. The time asymmetric profile of the etalon-generated pulse is shown to be responsible for both of these observations. A theoretical discussion is presented which quantitatively supports this hypothesis. It is concluded that etalons are the ideal method for the generation of narrowband ps pulses for FSRS because of the optical simplicity, efficiency, improved FSRS intensity and reduced backgrounds.

  20. A compact and versatile pulse generation and shaping subsystem for high energy laser systems

    Energy Technology Data Exchange (ETDEWEB)

    Van Wonterghem, B.M.; Speck, D.R.; Norman, M.; Wilcox, R.B.; Karpenko, V.P.; Richards, J.B.

    1993-01-01

    This paper describes the amplifier and beam shaping section of a new pulse generation system that will drive the Beamlet laser at LLNL. The master oscillator and pulse shaping system are described in an accompanying contribution. A modified regenerative amplifier produces a gain of 10[sup 9] to bring the oscillator pulses to the mJ-level. A serrated aperture and birefringent beam shaper produce a flat-topped square beam with high fill factor. A single four-passed Nd:glass rod amplifier provides sufficient gain to generate the desired 12 J output energy in a 3 nsec pulse with very small beam profile, wavefront and pulse shape distortion. We present a description of the system components, followed by a discussion of its performance, based upon over 150 full front end shots being completed since its assembly.

  1. A compact and versatile pulse generation and shaping subsystem for high energy laser systems

    Energy Technology Data Exchange (ETDEWEB)

    Van Wonterghem, B.M.; Speck, D.R.; Norman, M.; Wilcox, R.B.; Karpenko, V.P.; Richards, J.B.

    1993-01-01

    This paper describes the amplifier and beam shaping section of a new pulse generation system that will drive the Beamlet laser at LLNL. The master oscillator and pulse shaping system are described in an accompanying contribution. A modified regenerative amplifier produces a gain of 10{sup 9} to bring the oscillator pulses to the mJ-level. A serrated aperture and birefringent beam shaper produce a flat-topped square beam with high fill factor. A single four-passed Nd:glass rod amplifier provides sufficient gain to generate the desired 12 J output energy in a 3 nsec pulse with very small beam profile, wavefront and pulse shape distortion. We present a description of the system components, followed by a discussion of its performance, based upon over 150 full front end shots being completed since its assembly.

  2. Contrast enhancement via shaped Raman pulses for thermal cold atom cloud interferometry

    Science.gov (United States)

    Luo, Yukun; Yan, Shuhua; Hu, Qingqing; Jia, Aiai; Wei, Chunhua; Yang, Jun

    2016-12-01

    Interferometry with thermal cold atom clouds provides high particle flux and low quantum projection noise but is limited by the rapid reduction of fringe contrast. We propose an improved method based on temporally shaped pulses to address the issue of the off-resonance dispersion and enhance the contrast. Theoretical analysis and construction principle for shaped pulses are demonstrated. The fidelity of single π and π/2 pulses as well as a complete interferometer sequence are investigated. Comparisons are ade between the traditional pulse and several alternative shaped pulses to verify the feasibility and find an efficient choice among them. Practical implementation scheme and possible error sources are also discussed. The results show a great improvement in contrast and robust phase response for high atomic temperature up to several tens of μK.

  3. Identification alpha and gamma quantum at the pulse shape of the scintillates splash

    Directory of Open Access Journals (Sweden)

    V. I. Kornaga

    2008-05-01

    Full Text Available The methods of different scintillates splash alpha and gamma quantum at the pulse shape have been considered in experiment researches of the core's structure and mechanisms of the nuclear reaction.

  4. Nonparametric Interference Suppression Using Cyclic Wiener Filtering: Pulse Shape Design and Performance Evaluation

    Directory of Open Access Journals (Sweden)

    Anass Benjebbour

    2008-02-01

    Full Text Available In the future, there will be a growing need for more flexible but efficient utilization of radio resources. Increased flexibility in radio transmission, however, yields a higher likelihood of interference owing to limited coordination among users. In this paper, we address the problem of flexible spectrum sharing where a wideband single carrier modulated signal is spectrally overlapped by unknown narrowband interference (NBI and where a cyclic Wiener filter is utilized for nonparametric NBI suppression at the receiver. The pulse shape design for the wideband signal is investigated to improve the NBI suppression capability of cyclic Wiener filtering. Specifically, two pulse shaping schemes, which outperform existing raised cosine pulse shaping schemes even for the same amount of excess bandwidth, are proposed. Based on computer simulation, the interference suppression capability of cyclic Wiener filtering is evaluated for both the proposed and existing pulse shaping schemes under several interference conditions and over both AWGN and Rayleigh fading channels.

  5. Nonparametric Interference Suppression Using Cyclic Wiener Filtering: Pulse Shape Design and Performance Evaluation

    Directory of Open Access Journals (Sweden)

    Benjebbour Anass

    2008-01-01

    Full Text Available Abstract In the future, there will be a growing need for more flexible but efficient utilization of radio resources. Increased flexibility in radio transmission, however, yields a higher likelihood of interference owing to limited coordination among users. In this paper, we address the problem of flexible spectrum sharing where a wideband single carrier modulated signal is spectrally overlapped by unknown narrowband interference (NBI and where a cyclic Wiener filter is utilized for nonparametric NBI suppression at the receiver. The pulse shape design for the wideband signal is investigated to improve the NBI suppression capability of cyclic Wiener filtering. Specifically, two pulse shaping schemes, which outperform existing raised cosine pulse shaping schemes even for the same amount of excess bandwidth, are proposed. Based on computer simulation, the interference suppression capability of cyclic Wiener filtering is evaluated for both the proposed and existing pulse shaping schemes under several interference conditions and over both AWGN and Rayleigh fading channels.

  6. Self-similar Shape Mode of Optical Pulse Propagation in Medium with non-stationary Absorption

    Science.gov (United States)

    Trofimov, Vycheslav A.; Lysak, Tatyana M.; Fedotov, Mihail V.; Prokopenko, Alexander S.

    2015-03-01

    We discuss laser pulse propagation with the self-similar shape in a medium with instantaneous nonlinear absorption. We consider two cases of the laser pulse propagation. First one corresponds to problem of laser-induced plasma generation in silica under action of TW laser pulse. The second one corresponds to femtosecond laser pulse propagation in medium with nanoparticles of noble metals. In both cases the mode of the self-similar shape of pulse is of interest. We discuss also a physical mechanism of non-linear acceleration or slowing-down for laser pulse propagation in a medium with nanoparticles. The last phenomena are important, in particular, for a problem of data processing of all optical method. We used analytical approach for considered problem as well as computer simulation.

  7. Simulation and real-time analysis of pulse shapes from segmented HPGe-detectors

    Energy Technology Data Exchange (ETDEWEB)

    Schlarb, Michael Christian

    2009-11-17

    is accomplished by searching the simulated signal basis for the best agreement with the experimental signal. The particular challenge lies in the binomial growth of the search space making an intelligent search algorithm compulsory. In order to reduce the search space, the starting time t{sub 0} for the pulse shapes can be determined independently by a neural network algorithm, developed in the scope of this work. The precision of 2 - 5ns(FWHM), which is far beyond the sampling time of the digitizers, directly influences the attainable position resolution. For the search of the positions the so-called 'Fully Informed Particle Swarm' (FIPS) was developed, implemented and has proofed to be very efficient. Depending on the number of interactions an accurate reconstruction of the positions is accomplished within several {mu}s to a few ms. Data from a simulated (d, p) reaction in inverse kinematics, using a {sup 48}Ti beam at an energy of 100 MeV, impinging on a deuterated titanium target were used to test the capabilities of the developed PSA algorithms in a realistic setting. In the ideal case of an extensive PSA an energy resolution of 2.8 keV (FWHM) for the 1382 keV line of {sup 49}Ti results but this approach works only on the limited amount of data in which only a single segment has been hit. Selecting the same events the FIPS-PSA Algorithm achieves 3.3 keV with an average computation time of {proportional_to} 0.9ms. The extensive grid search, by comparison takes 27ms. Including events with multiple hit segments increases the statistics roughly twofold and the resolution of FIPS-PSA does not deteriorate significantly at an average computing time of 2.2ms. (orig.)

  8. Time and Frequency Localized Pulse Shape for Resolution Enhancement in STFT-BOTDR

    Directory of Open Access Journals (Sweden)

    Linqing Luo

    2016-01-01

    Full Text Available Short-Time Fourier Transform-Brillouin Optical Time-Domain Reflectometry (STFT-BOTDR implements STFT over the full frequency spectrum to measure the distributed temperature and strain along the optic fiber, providing new research advances in dynamic distributed sensing. The spatial and frequency resolution of the dynamic sensing are limited by the Signal to Noise Ratio (SNR and the Time-Frequency (T-F localization of the input pulse shape. T-F localization is fundamentally important for the communication system, which suppresses interchannel interference (ICI and intersymbol interference (ISI to improve the transmission quality in multicarrier modulation (MCM. This paper demonstrates that the T-F localized input pulse shape can enhance the SNR and the spatial and frequency resolution in STFT-BOTDR. Simulation and experiments of T-F localized different pulses shapes are conducted to compare the limitation of the system resolution. The result indicates that rectangular pulse should be selected to optimize the spatial resolution and Lorentzian pulse could be chosen to optimize the frequency resolution, while Gaussian shape pulse can be used in general applications for its balanced performance in both spatial and frequency resolution. Meanwhile, T-F localization is proved to be useful in the pulse shape selection for system resolution optimization.

  9. A Novel Ring Shaped Photodiode for Reflectance Pulse Oximetry in Wireless Applications

    DEFF Research Database (Denmark)

    Duun, Sune; Haahr, Rasmus Grønbek; Birkelund, Karen;

    2007-01-01

    We present a pulse oximeter for use in home-care applications in a sticking patch with integrated electronics. The core in the pulse oximeter is a large ring shaped backside silicon pn photodiode placed around a Ledtronics dual LED with wavelengths of 660 nm and 940 nm. The concentric photodiode...

  10. Topology optimization of pulse shaping filters using the Hilbert transform envelope extraction

    DEFF Research Database (Denmark)

    Lazarov, Boyan Stefanov; Matzen, René; Elesin, Yuriy

    2011-01-01

    Time domain topology optimization is applied to design pulse shaping filters. The objective function depends on the pulse envelope, which is extracted by utilizing the Hilbert transform. The gradients with respect to the topology optimization variables are derived, and the optimization methodology...

  11. Plasma shape control by pulsed solenoid on laser ion source

    Science.gov (United States)

    Sekine, M.; Ikeda, S.; Romanelli, M.; Kumaki, M.; Fuwa, Y.; Kanesue, T.; Hayashizaki, N.; Lambiase, R.; Okamura, M.

    2015-09-01

    A Laser ion source (LIS) provides high current heavy ion beams with a very simple mechanical structure. Plasma is produced by a pulsed laser ablation of a solid state target and ions are extracted by an electric field. However, it was difficult to manipulate the beam parameters of a LIS, since the plasma condition could only be adjusted by the laser irradiation condition. To enhance flexibility of LIS operation, we employed a pulsed solenoid in the plasma drift section and investigated the effect of the solenoid field on singly charged iron beams. The experimentally obtained current profile was satisfactorily controlled by the pulsed magnetic field. This approach may also be useful to reduce beam emittance of a LIS.

  12. Plasma shape control by pulsed solenoid on laser ion source

    Energy Technology Data Exchange (ETDEWEB)

    Sekine, M. [Tokyo Institute of Technology, Meguro-ku, Tokyo 2-12-1 (Japan); RIKEN, Wako, Saitama 351-0198 (Japan); Ikeda, S. [Tokyo Institute of Technology, Yokohama, Kanagawa 226-8502 (Japan); RIKEN, Wako, Saitama 351-0198 (Japan); Romanelli, M. [Cornell University, Ithaca, NY 14850 (United States); Kumaki, M. [RIKEN, Wako, Saitama 351-0198 (Japan); Waseda University, Shinjuku, Tokyo 169-0072 (Japan); Fuwa, Y. [RIKEN, Wako, Saitama 351-0198 (Japan); Kyoto University, Uji, Kyoto 611-0011 (Japan); Kanesue, T. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Hayashizaki, N. [Tokyo Institute of Technology, Meguro-ku, Tokyo 2-12-1 (Japan); Lambiase, R. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Okamura, M. [RIKEN, Wako, Saitama 351-0198 (Japan); Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2015-09-21

    A Laser ion source (LIS) provides high current heavy ion beams with a very simple mechanical structure. Plasma is produced by a pulsed laser ablation of a solid state target and ions are extracted by an electric field. However, it was difficult to manipulate the beam parameters of a LIS, since the plasma condition could only be adjusted by the laser irradiation condition. To enhance flexibility of LIS operation, we employed a pulsed solenoid in the plasma drift section and investigated the effect of the solenoid field on singly charged iron beams. The experimentally obtained current profile was satisfactorily controlled by the pulsed magnetic field. This approach may also be useful to reduce beam emittance of a LIS.

  13. INTELLIGENT CONTROL SYSTEM OF PULSED MAG WELDING INVERTER BASED ON DIGITAL SIGNAL PROCESSOR

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A fuzzy logic intelligent control system of pulsed MAG welding inverter based on digital signal processor (DSP) is proposed to obtain the consistency of arc length in pulsed MAG welding. The proposed control system combines the merits of intelligent control with DSP digital control. The fuzzy logic intelligent control system designed is a typical two-input-single-output structure, and regards the error and the change in error of peak arc voltage as two inputs and the background time as single output. The fuzzy logic intelligent control system is realized in a look-up table (LUT) method by using MATLAB based fuzzy logic toolbox, and the implement of LUT method based on DSP is also discussed. The pulsed MAG welding experimental results demonstrate that the developed fuzzy logic intelligent control system based on DSP has strong arc length controlling ability to accomplish the stable pulsed MAG welding process and controls pulsed MAG welding inverter digitally and intelligently.

  14. Analytical modeling of pulse-pileup distortion using the true pulse shape, with applications to Fermi-GBM

    CERN Document Server

    Chaplin, Vandiver; Briggs, Michael; Connaughton, Valerie

    2012-01-01

    Pulse-pileup affects most photon counting systems and occurs when photon detections occur faster than the detector's registration and recovery time. At high input rates, shaped pulses interfere and the source spectrum, as well as intensity information, get distorted. For instruments using bipolar pulse shaping there are two aspects to consider: `peak' and `tail' pileup effects, which raise and lower the measured energy, respectively. Peak effects have been extensively modeled in the past. Tail effects have garnered less attention due to the increased complexity: bipolar tails mean the tail pulse-height measurement depends on events in more than one time interval. We leverage previous work to derive an accurate, semi-analytical prediction for peak and tail pileup, up to high orders. We use the true pulse shape from the detectors of the Fermi Gamma-ray Burst Monitor. The measured spectrum is calculated by writing exposure time as a state-space expansion of overlapping pileup states and is valid up to very high ...

  15. Pulse shaping and characterization with a 4f system

    CSIR Research Space (South Africa)

    Botha, N

    2010-10-01

    Full Text Available . 3. References [1] A. M. Weiner, Review of Scientific Instruments, Volume 71, Number 5, p. 1929-1960 [2] M. Cavallari, G.M. Gale, F. Hache, L.I. Pavlov, E. Rousseau, Optics Communication, Volume 114, p. 329 - 332 Fig.1: 4f pulse shaper...

  16. Electron pulse shaping in the FELIX RF accelerator

    NARCIS (Netherlands)

    Weits, H. H.; van der Geer, C. A. J.; Oepts, D.; van der Meer, A. F. G.

    1999-01-01

    The FELIX free-electron laser uses short pulses of relativistic electrons produced by an RF accelerator. The design target for the duration of these electron bunches was around 3 ps. In experiments we observed that the bunches emit coherently enhanced spontaneous emission (CSE) when they travel thro

  17. Electron pulse shaping in the FELIX RF accelerator

    NARCIS (Netherlands)

    Weits, H. H.; van der Geer, C. A. J.; Oepts, D.; van der Meer, A. F. G.

    1999-01-01

    The FELIX free-electron laser uses short pulses of relativistic electrons produced by an RF accelerator. The design target for the duration of these electron bunches was around 3 ps. In experiments we observed that the bunches emit coherently enhanced spontaneous emission (CSE) when they travel

  18. Coherent control in room-temperature quantum dot semiconductor optical amplifiers using shaped pulses

    CERN Document Server

    Karni, Ouri; Eisenstein, Gadi; Ivanov, Vitalii; Reithmaier, Johann Peter

    2016-01-01

    We demonstrate the ability to control quantum coherent Rabi-oscillations in a room-temperature quantum dot semiconductor optical amplifier (SOA) by shaping the light pulses that trigger them. The experiments described here show that when the excitation is resonant with the short wavelength slope of the SOA gain spectrum, a linear frequency chirp affects its ability to trigger Rabi-oscillations within the SOA: A negative chirp inhibits Rabi-oscillations whereas a positive chirp can enhance them, relative to the interaction of a transform limited pulse. The experiments are confirmed by a numerical calculation that models the propagation of the experimentally shaped pulses through the SOA.

  19. Generation, shaping, compression, characterization and application of intense ultrashort laser pulses

    CERN Document Server

    Cheng, Z

    2001-01-01

    Recently, the development of intense ultrashort laser pulses has attracted much interest because of their significant applications in many fields of science and technology. This thesis contributes to the generation, shaping, compression, characterization and application of intense ultrashort laser pulses as follows: 1. Laser pulses of 17.5-fs with a peak power of 0.1-TW at 1-kHz repetition rate have been generated by a compact single-stage ten-pass Ti:sapphire amplifier system with a high-order-dispersion-mirror compensator and a spectral shaping for the first time. The experimental results are in reasonable agreement with numerical calculations. 2. The first experimental study on arbitrary shaping of intense ultrashort pulses has been conducted in a kHz amplifier system capable of generating 27 fs pulses by using an acousto-optic programmable dispersive filter (AOPDF). 17-fs transform-limited pulses have been achieved and arbitrary shaping of these 17-fs pulses has been demonstrated both in the temporal and ...

  20. Microstructuring of soft organic matter by temporally shaped femtosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Rebollar, Esther, E-mail: e.rebollar@iqfr.csic.es [Instituto de Química Física Rocasolano, IQFR-CSIC, Serrano 119, 28006 Madrid (Spain); Mildner, Jutta; Götte, Nadine; Otto, Dirk; Sarpe, Cristian; Köhler, Jens; Wollenhaupt, Matthias; Baumert, Thomas [Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel (Germany); Castillejo, Marta [Instituto de Química Física Rocasolano, IQFR-CSIC, Serrano 119, 28006 Madrid (Spain)

    2014-05-01

    Thin films of the biopolymers gelatine and chitosan were treated using femtosecond pulse shaping techniques combined with a microscope-based setup for material processing. The polymer films were irradiated with laser pulses of 35 fs and a central wavelength of 790 nm provided by an amplified Ti:Sapphire system. The effect of temporal pulse shaping, with quadratic and cubic spectral phases, on the induced morphology was analyzed by characterization of the created surface structures via scanning electron microscopy. We observed different material modification thresholds and different structure sizes for temporally asymmetric pulse shapes. The results indicate the possibility of control of the generated microstructures and are discussed in relation to the formation of free electrons and the different contributions of multi-photon and avalanche ionization processes.

  1. Fluorescence anisotropy excitation by polarization-shaped laser pulses after transmission through a kagome fiber

    Science.gov (United States)

    Otto, J.; Patas, A.; Althoff, J.; Lindinger, A.

    2016-08-01

    We report improved fluorescence contrast between dyes by two-photon excitation with polarization-shaped laser pulses after transmission through a kagome fiber utilizing the anisotropy of the dye molecules. Particularly phase- and polarization-tailored pulse shapes are employed for two-photon excited fluorescence of dyes in a liquid environment at the distal end of the kagome fiber. The distortions due to the optical fiber properties are precompensated in order to receive predefined polarization-shaped laser pulses after the kagome fiber. This enables to optimally excite one dye in one polarization direction and simultaneously the other dye in the other polarization direction. The presented method has a high potential for endoscopic applications due to the unique properties of kagome fibers for guiding ultrashort laser pulses.

  2. Pulse-shaping mechanism in colliding-pulse mode-locked laser diodes

    DEFF Research Database (Denmark)

    Bischoff, Svend; Sørensen, Mads Peter; Mørk, J.;

    1995-01-01

    The large signal dynamics of passively colliding pulse mode-locked laser diodes is studied. We derive a model which explains modelocking via the interplay of gain and loss dynamics; no bandwidth limiting element is necessary for pulse formation. It is found necessary to have both fast and slow...... absorber dynamics to achieve mode-locking. Significant chirp is predicted for pulses emitted from long lasers, in agreement with experiment. The pulse width shows a strong dependence on both cavity and saturable absorber length. (C) 1995 American Institute of Physics....

  3. Discrete excitation of mode pulses using a diode-pumped solid-state digital laser

    CSIR Research Space (South Africa)

    Ngcobo, Sandile

    2016-02-01

    Full Text Available In this paper, we experimentally demonstrate novel method of generating discrete excitation of on-demand Lagaurre-Gaussian (LG) mode pulses, in a diode pumped solid-state digital laser. The digital laser comprises of an intra-cavity spatial light...

  4. Application of wave-shape functions and Synchrosqueezing transform to pulse signal analysis

    CERN Document Server

    Wu, Hau-tieng; Wu, Han-Kuei; Wang, Chun-Li; Yang, Yueh-Lung; Wu, Wen-Hsiang

    2015-01-01

    We apply the recently developed adaptive non-harmonic model based on the wave-shape function, as well as the time-frequency analysis tool called synchrosqueezing transform (SST) to model and study the pulse wave signal. Based on the wave shape function model and SST, we extract features, called the spectral pulse signature, based on the functional regression technique, to characterize the hemodynamics from the pulse wave signals. To demonstrate how the algorithm and the extracted features work, we study the radial pulse wave signal recorded by the sphygmomanometer from normal subjects and patients with congestive heart failure. The analysis results suggest the potential of the proposed signal processing approach to extract health-related hemodynamics features. In addition, it shows that different positions of the radial artery contain significant different information, which is compatible with the empirical conclusion of the pulse diagnosis in the traditional Chinese medicine.

  5. Pulse shape distortion in a 2-stage all-fiber Er-doped amplifier

    Science.gov (United States)

    Michalska, M.; Mamajek, M.

    2013-07-01

    The issue of temporal pulse distortion occurring during amplification process in a 2-stage, fiber amplifier, operating in the eye-safe spectral region, is discussed. The amplifier was built in a Master Oscillator Power Amplifier (MOPA) configuration and seeded by a distributed feedback (DFB) laser providing nanosecond pulses at a repetition rate of 20 kHz. It operated at a wavelength of 1549.13 nm and generated over 200 mW of output power with a slope efficiency of up to 28%. The comparison between the calculated and measured results on saturation-induced pulse shape deformation, for ~300-ns pulses, is presented. The analyzed pulse shapes embraced rectangle, Gaussian, triangle and "M" letter.

  6. Effect of Pulse Shaping on Observing Coherent Energy Transfer in Single Light-Harvesting Complexes.

    Science.gov (United States)

    Song, Kai; Bai, Shuming; Shi, Qiang

    2016-11-17

    Recent experimental and theoretical studies have revealed that quantum coherence plays an important role in the excitation energy transfer in photosynthetic light-harvesting (LH) complexes. Inspired by the recent single-molecule two-color double-pump experiment, we theoretically investigate the effect of pulse shaping on observing coherent energy transfer in the single bacterial LH2 complex. It is found that quantum coherent energy transfer can be observed when the time delay and phase difference between the two laser pulses are controlled independently. However, when the two-color pulses are generated using the pulse-shaping method, how the laser pulses are prepared is crucial to the observation of quantum coherent energy transfer in single photosynthetic complexes.

  7. Coherent control with shaped femtosecond laser pulses applied to ultracold molecules

    CERN Document Server

    Salzmann, W; Wester, R; Weidemüller, M; Merli, A; Weber, S M; Sauer, F; Plewicki, M; Weise, F; Esparza, A M; Wöste, L; Lindinger, A; Salzmann, Wenzel; Poschinger, Ulrich; Wester, Roland; Weidemueller, Matthias; Merli, Andrea; Weber, Stefan M.; Sauer, Franziska; Plewicki, Mateusz; Weise, Fabian; Esparza, Aldo Mirabal; Woeste, Ludger; Lindinger, Albrecht

    2005-01-01

    We report on coherent control of excitation processes of translationally ultracold rubidium dimers in a magneto-optical trap by using shaped femtosecond laser pulses. Evolution strategies are applied in a feedback loop in order to optimize the photoexcitation of the Rb2 molecules, which subsequently undergo ionization or fragmentation. A superior performance of the resulting pulses compared to unshaped pulses of the same pulse energy is obtained by distributing the energy among specific spectral components. The demonstration of coherent control to ultracold ensembles opens a path to actively influence fundamental photo-induced processes in molecular quantum gases.

  8. Systematic uncertainties of artificial neural-network pulse-shape discrimination for $0\

    CERN Document Server

    Abt, I; Cossavella, F; Majorovits, B; Palioselitis, D; Volynets, O

    2014-01-01

    A pulse-shape discrimination method based on artificial neural networks was applied to pulses simulated for different background, signal and signal-like interactions inside a germanium detector. The simulated pulses were used to investigate the systematic uncertainties of the method. It is verified that neural networks are well-suited to identify background pulses in true-coaxial high-purity germanium detectors. The systematic uncertainty on the signal recognition efficiency derived using signal-like samples from calibration measurements is estimated to be 5\\%. This uncertainty is due to differences between signal and calibration samples.

  9. Nyquist pulse shaping using arrayed waveguide grating routers.

    Science.gov (United States)

    Xie, Yiwei; Zhuang, Leimeng; Zhu, Chen; Lowery, Arthur James

    2016-10-03

    We propose and demonstrate by simulations a novel Nyquist-WDM (N-WDM) superchannel transmitter based on an arrayed waveguide grating router (AWGR). This approach can generate Nyquist pulses at multiple wavelengths using a single AWGR. Results for a 3-channel 960-Gbit/s QPSK superchannel system show that a 10% guard band reduces the inter-channel interference (ICI) sufficiently. The design introduces less than 0.16-dB penalty when the waveguide loss is 2 dB/cm and 0.73-dB penalty when the standard deviation of phase error is 10°. Such Nyquist pulse shapers can be realised on a chip scale using photonic integrated circuits technology, and could be compactly integrated with other functional components to create single-chip N-WDM superchannel transmitters.

  10. Pulse shape discrimination using EJ-299-33 plastic scintillator coupled with a Silicon Photomultiplier array

    Science.gov (United States)

    Liao, Can; Yang, Haori

    2015-07-01

    Recent developments in organic plastic scintillators capable of pulse shape discrimination (PSD) have gained much interest. Novel photon detectors, such as Silicon Photomultipliers (SiPMs), offer numerous advantages and can be used as an alternative to conventional photo multiplier tubes (PMTs) in many applications. In this work, we evaluate the PSD performance of the EJ-299-33 plastic scintillator coupled with a SiPM array. 2D PSD plots as well as the Figure of Merit (FOM) parameters are presented to demonstrate the PSD capability of EJ-299-33 using a SiPM as the light sensor. The best FOM of 0.76 was observed with a 1.0 MeVee (MeV-electron-equivalent) energy threshold, despite the high noise level of the SiPM array. A high-speed digital oscilloscope was used to acquire data, which was then processed offline in MATLAB. A performance comparison between two different PSD algorithms was carried out. The dependence of PSD quality on the sampling rate was also evaluated, stimulated by the interest to implement this setup for handheld applications where power consumption is crucial.

  11. Laser induced periodic surface structuring on Si by temporal shaped femtosecond pulses.

    Science.gov (United States)

    Almeida, G F B; Martins, R J; Otuka, A J G; Siqueira, J P; Mendonca, C R

    2015-10-19

    We investigated the effect of temporal shaped femtosecond pulses on silicon laser micromachining. By using sinusoidal spectral phases, pulse trains composed of sub-pulses with distinct temporal separations were generated and applied to the silicon surface to produce Laser Induced Periodic Surface Structures (LIPSS). The LIPSS obtained with different sub-pulse separation were analyzed by comparing the intensity of the two-dimensional fast Fourier Transform (2D-FFT) of the AFM images of the ripples (LIPSS). It was observed that LIPSS amplitude is more emphasized for the pulse train with sub-pulses separation of 128 fs, even when compared with the Fourier transform limited pulse. By estimating the carrier density achieved at the end of each pulse train, we have been able to interpret our results with the Sipe-Drude model, that predicts that LIPSS efficacy is higher for a specific induced carrier density. Hence, our results indicate that temporal shaping of the excitation pulse, performed by spectral phase modulation, can be explored in fs-laser microstructuring.

  12. Extremely Nonlinear Optics Using Shaped Pulses Spectrally Broadened in an Argon- or Sulfur Hexafluoride-Filled Hollow-Core Fiber

    Directory of Open Access Journals (Sweden)

    Andreas Hoffmann

    2015-11-01

    Full Text Available In this contribution we present a comparison of the performance of spectrally broadened ultrashort pulses using a hollow-core fiber either filled with argon or sulfur hexafluoride (SF6 for demanding pulse-shaping experiments. The benefits of both gases for pulse-shaping are studied in the highly nonlinear process of high-harmonic generation. In this setup, temporally shaping the driving laser pulse leads to spectrally shaping of the output extreme ultraviolet (XUV spectrum, where total yield and spectral selectivity in the XUV are the targets of the optimization approach. The effect of using sulfur hexafluoride for pulse-shaping the XUV yield can be doubled compared to pulse compression and pulse-shaping using argon and the spectral range for selective optimization of a single harmonic can be extended. The obtained results are of interest for extending the range of ultrafast science applications drawing on tailored XUV fields.

  13. Particle identification using the ΔE-E technique and pulse shape discrimination with the silicon detectors of the FAZIA project

    Science.gov (United States)

    Carboni, S.; Barlini, S.; Bardelli, L.; Le Neindre, N.; Bini, M.; Borderie, B.; Bougault, R.; Casini, G.; Edelbruck, P.; Olmi, A.; Pasquali, G.; Poggi, G.; Rivet, M. F.; Stefanini, A. A.; Baiocco, G.; Berjillos, R.; Bonnet, E.; Bruno, M.; Chbihi, A.; Cruceru, I.; Degerlier, M.; Dueñas, J. A.; Galichet, E.; Gramegna, F.; Kordyasz, A.; Kozik, T.; Kravchuk, V. L.; Lopez, O.; Marchi, T.; Martel, I.; Morelli, L.; Parlog, M.; Petrascu, H.; Rosato, E.; Seredov, V.; Vient, E.; Vigilante, M.; Alba, R.; Santonocito, D.; Maiolino, C.; Fazia Collaboration

    2012-02-01

    The response of silicon-silicon-CsI(Tl) and silicon-CsI(Tl) telescopes to fragments produced in nuclear interactions has been studied. The telescopes were developed within the FAZIA collaboration. The capabilities of two methods are compared: (a) the standard ΔE-E technique and (b) the digital Pulse Shape Analysis technique (for identification of nuclear fragments stopped in a single Si-layer). In a test setup, nuclear fragments covering a large range in nuclear charge, mass and energy were detected. They were produced in nuclear reactions induced by a 35A MeV beam of 129Xe impinging on various targets. It was found that the ΔE-E correlations allow the identification of all isotopes up to Z˜25. With the digital Pulse Shape Analysis it is possible to fully distinguish the charge of stopped nuclei up to the maximum available Z (slightly over that of the beam, Z=54).

  14. Particle identification using the {Delta}E-E technique and pulse shape discrimination with the silicon detectors of the FAZIA project

    Energy Technology Data Exchange (ETDEWEB)

    Carboni, S., E-mail: carboni@fi.infn.it [University of Florence (Italy); INFN Florence (Italy); Barlini, S.; Bardelli, L. [University of Florence (Italy); INFN Florence (Italy); Le Neindre, N. [Laboratoire de Physique Corpusculaire, IN2P3-CNRS/ENSICAEN/Universite, F-14050 Caen cedex (France); Bini, M. [University of Florence (Italy); INFN Florence (Italy); Borderie, B. [Institut de Physique Nucleaire, CNRS/IN2P3 and University of Paris-Sud XI, Orsay (France); Bougault, R. [Laboratoire de Physique Corpusculaire, IN2P3-CNRS/ENSICAEN/Universite, F-14050 Caen cedex (France); Casini, G. [INFN Florence (Italy); Edelbruck, P. [Institut de Physique Nucleaire, CNRS/IN2P3 and University of Paris-Sud XI, Orsay (France); Olmi, A. [INFN Florence (Italy); Pasquali, G.; Poggi, G. [University of Florence (Italy); INFN Florence (Italy); Rivet, M.F. [Institut de Physique Nucleaire, CNRS/IN2P3 and University of Paris-Sud XI, Orsay (France); Stefanini, A.A. [University of Florence (Italy); INFN Florence (Italy); Baiocco, G. [INFN (Italy); University of Bologna (Italy); Berjillos, R. [Huelva University (Spain); Bonnet, E. [GANIL Caen (France); Bruno, M. [INFN (Italy); University of Bologna (Italy); Chbihi, A. [GANIL Caen (France); Cruceru, I. [Horia Hulubei National Institute of Physics and Nuclear Engineering, RO-077125 Bucharest (Romania); and others

    2012-02-01

    The response of silicon-silicon-CsI(Tl) and silicon-CsI(Tl) telescopes to fragments produced in nuclear interactions has been studied. The telescopes were developed within the FAZIA collaboration. The capabilities of two methods are compared: (a) the standard {Delta}E-E technique and (b) the digital Pulse Shape Analysis technique (for identification of nuclear fragments stopped in a single Si-layer). In a test setup, nuclear fragments covering a large range in nuclear charge, mass and energy were detected. They were produced in nuclear reactions induced by a 35A MeV beam of {sup 129}Xe impinging on various targets. It was found that the {Delta}E-E correlations allow the identification of all isotopes up to Z{approx}25. With the digital Pulse Shape Analysis it is possible to fully distinguish the charge of stopped nuclei up to the maximum available Z (slightly over that of the beam, Z=54).

  15. Development of a High-Speed Digitizer to Time Resolve Nanosecond Fluorescence Pulses

    Directory of Open Access Journals (Sweden)

    E. Moreno-García

    2012-04-01

    Full Text Available The development of a high-speed digitizer system to measure time-domain voltage pulses in nanoseconds range is presented in this work. The digitizer design includes a high performance digital signal processor, a high-bandwidth analog-to-digital converter of flash-type, a set of delay lines, and a computer to achieve the time-domain measurements. A program running on the processor applies a time-equivalent sampling technique to acquire the input pulse. The processor communicates with the computer via a serial port RS-232 to receive commands and to transmit data. A control program written in LabVIEW 7.1 starts an acquisition routine in the processor. The program reads data from processor point by point in each occurrence of the signal, and plots each point to recover the time-resolved input pulse after n occurrences. The developed prototype is applied to measure fluorescence pulses from a homemade spectrometer. For this application, the LabVIEW program was improved to control the spectrometer, and to register and plot time-resolved fluorescence pulses produced by a substance. The developed digitizer has 750 MHz of analog input bandwidth, and it is able to resolve 2 ns rise-time pulses with 150 ps of resolution and a temporal error of 2.6 percent.

  16. Shaping and timing gradient pulses to reduce MRI acoustic noise

    NARCIS (Netherlands)

    Segbers, Marcel; Sierra, Carlos V. Rizzo; Duifhuis, Hendrikus; Hoogduin, Johannes M.

    A method to reduce the acoustic noise generated by gradient systems in MRI has been recently proposed; such a method is based on the linear response theory. Since the physical cause of MRI acoustic noise is the time derivative of the gradient current, a common trapezoid current shape produces an

  17. Shaping and Timing Gradient Pulses to Reduce MRI Acoustic Noise

    NARCIS (Netherlands)

    Segbers, Marcel; Sierra, Carlos V. Rizzo; Duifhuis, Hendrikus; Hoogduin, Johannes M.

    2010-01-01

    A method to reduce the acoustic noise generated by gradient systems in MRI has been recently proposed; such a method is based on the linear response theory. Since the physical cause of MRI acoustic noise is the time derivative of the gradient current, a common trapezoid current shape produces an aco

  18. Adaptive control of lasers and their interactions with matter using femtosecond pulse shaping

    Science.gov (United States)

    Efimov, Anatoly

    Coherent control of chemical reactions, atomic and molecular systems, lattice dynamics, and electronic motion rely on femtosecond laser sources capable of producing programmable arbitrarily shaped waveforms. To enter the time scale of natural dynamic processes in many systems, femtosecond pulse shaping techniques must be extended to the ultrashort pulse domain (teach our laser to control its own phase by using spectral blueshifting in a rapidly created plasma as a feedback to the algorithm. Control of lattice vibrations has long been sought as a means of studying phonon-related processes in solids. In addition, generation and control of large-amplitude optical phonon modes may open a path to femtosecond time- resolved studies of structural phase transitions and production of ultrashort shaped X-ray pulses. We perform pump-probe phase-resolved measurements and control of optical A1g mode in sapphire through shaped-pulse impulsive stimulated Raman scattering (ISRS). We chose this material as a candidate for possible nonlinear oscillations regime for its wide band gap and superior optical properties allowing for high-energy excitation. To enter a nonlinear regime, however, complex asymmetric multiple-pulse excitation is required. Therefore, we make a detailed proposal of the experimental adaptive feedback implementation for optimization of phonon amplitude based on the coherent probe scattering and a novel phase mask calculation algorithm for the real-time asymmetric pulse train generation.

  19. Shaping the Curriculum: The Power of a Library's Digital Resources

    Science.gov (United States)

    Kirkwood, Patricia

    2011-01-01

    Researchers were the first adopters of digital resources available through the library. Online journals and databases make finding research articles much easier than when this author started as a librarian more than 20 years ago. Speedier interlibrary loan due to digital delivery means research materials are never far away. Making it easier for…

  20. Shaping Our World: Digital Storytelling and the Authoring of Society

    Science.gov (United States)

    Brzoska, Karen Lynn

    2009-01-01

    Globalization, networked societies, and a knowledge-based economy engender increasing reliance on digital communication technologies for the dissemination of information and ideas (Castells, Fernandez-Ardevol, Qiu & Sey, 2006). While the technological revolution has broadened access this digital domain, participants often adopt the passive…

  1. Laser-Pulse-Shape Control of Seeded QED Cascades

    CERN Document Server

    Tamburini, Matteo; Keitel, Christoph H

    2015-01-01

    The emergence of electron-positron cascades via ultrastrong electromagnetic fields constitutes a prominent manifestation of the complex interplay between strong-field QED processes and multiparticle dynamics. Here the onset and development of electron-positron cascades are investigated in the head-on collision of two realistic tightly focused ultraintense optical laser pulses in a tenuous gas. As a consequence of the large ponderomotive forces expelling all electrons of the gas from the focal volume, we demonstrate that the onset of QED cascades may be prevented even at intensities around $10^{26}\\;\\text{W/cm$^2$}$ by focusing the laser energy almost down to the diffraction limit. Alternatively, a well controlled development of a QED cascade may be facilitated at laser intensities below $10^{24}\\;\\text{W/cm$^2$}$ per beam by enlarged focal areas and a rapid rise of the pulse or at total powers near $20\\;\\text{PW}$ by employing suitable high-$Z$ gases.

  2. Improved methods for modeling pulse shapes of accreting millisecond pulsars

    CERN Document Server

    Leahy, D; Cadeau, C

    2006-01-01

    Raytracing computations for light emitted from the surface of a rapidly rotating neutron star are carried out in order to construct light curves for accreting millisecond pulsars. These calculations are for realistic models of rapidly rotating neutron stars which take into account both the correct exterior metric and the oblate shape of the star. We find that the most important effect, comparing the full raytracing computations with simpler approximations currently in use, arises from the oblate shape of the rotating star. Approximating a rotating neutron star as a sphere introduces serious errors in fitted values of the star's radius and mass if the rotation rate is very large. However, for lower rotation rates acceptable mass and radius values can be obtained using the spherical approximation.

  3. Time correlated measurements using plastic scintillators with neutron-photon pulse shape discrimination

    Science.gov (United States)

    Richardson, Norman E., IV

    nuclear and radiological material. Moreover, the production of 3He isotope as a byproduct of security programs was drastically decreased. This isotope shortage coupled with the disadvantages of relying on a detector that requires neutron moderation before the detection of fission neutrons, poses a significant challenge in supporting the existing detection systems and the development of future technologies. To address this problem, a reliable and accurate alternative technology to detect neutrons emitted in fissions must be developed. One such alternative technology that shows promise in this application is the use of scintillators based on solid state materials (plastics) which are sensitive to fast neutrons. However, plastic scintillators are also sensitive to photons. Hence, it is necessary to separate the neutron signals from the photon signals, using the pulse shape discrimination (PSD) analysis. The PSD is based on the comparison of the pulse shapes of digitized signal waveforms. This approach allows for the measurement of fast neutrons without the necessity of their moderation. Because the fission spectrum neutrons are mainly fast, methods employing fast neutron detection are applicable for the assay of fissile materials. In addition, the average time of scintillation of the plastic medium is much shorter than those of the gaseous counters, thus allowing scintillation detectors to be used in high count rate environments. Furthermore, the temporal information of the fast neutron detection using multiple sensors enables the time correlation analysis of the fission neutron multiplicity. The study of time correlation measurements of fast neutrons using the array of plastic scintillators is the basis of this work. The array of four plastic scintillator detectors equipped with the digital data acquisition and analysis system was developed. The digital PSD analysis of detector signals "on-the-fly" was implemented for the array. The time coincidence measurement technique

  4. Performance scaling via passive pulse shaping in cavity-enhanced optical parametric chirped-pulse amplification.

    Science.gov (United States)

    Siddiqui, Aleem M; Moses, Jeffrey; Hong, Kyung-Han; Lai, Chien-Jen; Kärtner, Franz X

    2010-06-15

    We show that an enhancement cavity seeded at the full repetition rate of the pump laser can automatically reshape small-signal gain across the interacting pulses in an optical parametric chirped-pulse amplifier for close-to-optimal operation, significantly increasing both the gain bandwidth and the conversion efficiency, in addition to boosting gain for high-repetition-rate amplification. Applied to a degenerate amplifier, the technique can provide an octave-spanning gain bandwidth.

  5. Double dumbbell shaped AgNi alloy by pulsed electrodeposition

    Science.gov (United States)

    Dhanapal, K.; Vasumathi, M.; Santhi, Kalavathy; Narayanan, V.; Stephen, A.

    2014-01-01

    Silver-Nickel is the well-known thermally immiscible system that makes them quite complex for the formation of alloy. This kind of alloy can be attained from electrodeposition method. In the present work, AgNi alloy was synthesized by pulsed electrodeposition in a single bath two electrode system with the use of anodic alumina membrane. The prepared AgNi alloy and pure Ag were characterized with X-ray Diffraction (XRD) for structural confirmation, Scanning Electron Microscopy (SEM) for morphological, and magnetic properties by Vibrating Sample Magnetometer, respectively. The X-ray Diffraction study shows the formation of cubic structure for pure Ag. SEM analysis reveals the double dumbbell morphology for AgNi alloy and spherically agglomeration for pure silver. Hysteresis behaviour from VSM measurement indicates that the AgNi alloy have good ferro-magnetic properties.

  6. Pulse shaping techniques for a high-g shock tester based on collision principle

    Science.gov (United States)

    Duan, Zhengyong; Tang, Chuansheng; Li, Yang; Han, Junliang; Wu, Guoxiong

    2016-09-01

    Pulse shaping techniques are discussed in this paper for the practicability of a developed high-g shock tester. The tester is based on collision principle where there is a one-level velocity amplifier. A theoretical and experimental study of pulse shaping techniques is presented. A model was built and theoretical formulae were deduced for the shock peak acceleration and its duration. Then theoretical analysis and some experiments were conducted. The test results verify the validity of theoretical model and show that the shock tester can generate the expected high-g shock pulses by integrated usage of different impact velocities and pulse shapers made from different materials. This is important in practical applications where the items under test can be shown to excite specific resonances at predetermined acceleration levels using the shock tester.

  7. Shaping the output pulse of a linear-transformer-driver module.

    Energy Technology Data Exchange (ETDEWEB)

    Long, Finis W.; McKee, G. Randall; Stoltzfus, Brian Scott; Woodworth, Joseph Ray; McKenney, John Lee; Fowler, William E.; Mazarakis, Michael Gerrassimos; Porter, John L.; Stygar, William A.; Savage, Mark Edward; LeChien, Keith, R.; Van De Valde, David M. (EG& G, Albuquerque, NM)

    2008-11-01

    We demonstrate that a wide variety of current-pulse shapes can be generated using a linear-transformer-driver (LTD) module that drives an internal water-insulated transmission line. The shapes are produced by varying the timing and initial charge voltage of each of the module's cavities. The LTD-driven accelerator architecture outlined in [Phys. Rev. ST Accel. Beams 10, 030401 (2007)] provides additional pulse-shaping flexibility by allowing the modules that drive the accelerator to be triggered at different times. The module output pulses would be combined and symmetrized by water-insulated radial-transmission-line impedance transformers [Phys. Rev. ST Accel. Beams 11, 030401 (2008)].

  8. Enhancing strong-field induced molecular vibration with femtosecond pulse shaping

    CERN Document Server

    Bitter, Martin; Milner, Valery

    2012-01-01

    This work investigates the utility of femtosecond pulse shaping in increasing the efficiency of Raman excitation of molecules in the strong-field interaction regime. We study experimentally and theoretically the effect of pulse shaping on the strength of non-resonant coherent anti-Stokes Raman scattering in iodine vapor at laser intensities exceeding $10^{13}$ W/cm$^2$. We show that unlike the perturbative case, shaping strong non-resonant laser pulses can increase the signal strength beyond that observed with the transform-limited excitation. Both adiabatic and non-adiabatic schemes of excitation are explored, and the differences of their potential in increasing the excitation efficiency are discussed.

  9. Measurements of Scintillation Efficiency and Pulse-Shape for Low Energy Recoils in Liquid Xenon

    CERN Document Server

    Akimov, D Y; Davidge, D; Dawson, J; Howard, A S; Ivaniouchenkov, Yu; Jones, W G; Joshi, M; Kudryavtsev, V A; Lawson, T B; Lebedenko, V; Lehner, M J; Lightfoot, P K; Liubarsky, I; Lüscher, R; McMillan, J E; Peak, C D; Quenby, J J; Spooner, N J C; Sumner, T J; Tovey, Daniel R; Ward, C K

    2002-01-01

    Results of observations of low energy nuclear and electron recoil events in liquid xenon scintillator detectors are given. The relative scintillation efficiency for nuclear recoils is 0.22 +/- 0.01 in the recoil energy range 40 keV - 70 keV. Under the assumption of a single dominant decay component to the scintillation pulse-shape the log-normal mean parameter T0 of the maximum likelihood estimator of the decay time constant for 6 keV < Eee < 30 keV nuclear recoil events is equal to 21.0 ns +/- 0.5 ns. It is observed that for electron recoils T0 rises slowly with energy, having a value ~ 30 ns at Eee ~ 15 keV. Electron and nuclear recoil pulse-shapes are found to be well fitted by single exponential functions although some evidence is found for a double exponential form for the nuclear recoil pulse-shape.

  10. Understanding the ATLAS electromagnetic barrel pulse shapes and the absolute electronic calibration

    CERN Document Server

    Neukermans, L; Zitoun, R

    2001-01-01

    We present an original method to undestand the calibration and physics pulse shapes collected in the 2000 barrel test beam runs with the prototype module. It is based on an electrical description of the calorimeter and its electronics. It allows an understanding of the physics pulse shapes and its absolute calibration (in microA/ADC) to a very good level of accuracy with a small number of parameters (capacitances and inductances). The electrical parameters found by this method agree with the direct measurements independantly performed on the prototype module. Optimal filtering coefficients can then be derived from these physics pulse shape predictions, and more crucial, an absolute electronic calibration. These coefficients are released in the official test beam software EMTB.

  11. Study of the shower maximum depth by the method of detection of the EAS Cerenkov light pulse shape

    Science.gov (United States)

    Aliev, N.; Alimov, T.; Kakhkharov, M.; Khakimov, N.; Makhmudov, B. M.; Rakhimova, N.; Tashpulatov, R.; Khristiansen, G. B.; Prosin, V. V.; Zhukov, V. Y.

    1985-01-01

    The results of processing the data on the shape of the EAS Cerenkov light pulses recorded by the extensive air showers (EAS) array are presented. The pulse FWHM is used to find the mean depth of EAS maximum.

  12. Shaping the electron beams with submicrosecond pulse duration in sources and electron accelerators with plasma emitters

    CERN Document Server

    Gushenets, V I

    2001-01-01

    One studies the techniques in use to shape submicrosecond electron beams and the physical processes associated with extraction of electrons from plasma in plasma emitters. Plasma emitter base sources and accelerators enable to generate pulse beams with currents varying from tens of amperes up to 10 sup 3 A, with current densities up to several amperes per a square centimeter, with pulse duration constituting hundreds of nanoseconds and with high frequencies of repetition

  13. Artificial neural network based pulse shape analysis in cryogenic detectors for rare event searches

    Energy Technology Data Exchange (ETDEWEB)

    Zoeller, Andreas [Physik Department E15, Technische Universitaet Muenchen, 85748 Garching (Germany); Collaboration: CRESST-Collaboration

    2015-07-01

    We present a method based on an Artificial Neural Network for a pulse shape analysis in cryogenic detectors. To train the neural network a huge amount of pulses with known properties are necessary. Therefore, a data-driven simulation used to generate these sets is explained. Furthermore, these simulations allow detailed studies, especially of the cut efficiency and the signal purity of the developed cut. First results are presented and compared with the performance of alternative algorithms.

  14. A robust method for pulse peak determination in a digital volume pulse waveform with a wandering baseline.

    Science.gov (United States)

    Jang, Dae-Geun; Farooq, Umar; Park, Seung-Hun; Hahn, Minsoo

    2014-10-01

    This paper presents a robust method for pulse peak determination in a digital volume pulse (DVP) waveform with a wandering baseline. A proposed new method uses a modified morphological filter (MMF) to eliminate a wandering baseline signal of the DVP signal with minimum distortion and a slope sum function (SSF) with an adaptive thresholding scheme to detect pulse peaks from the baseline-removed DVP signal. Further in order to cope with over-detected and missed pulse peaks, knowledge based rules are applied as a postprocessor. The algorithm automatically adjusts detection parameters periodically to adapt to varying beat morphologies and fluctuations. Compared with conventional methods (highpass filtering, linear interpolation, cubic spline interpolation, and wavelet adaptive filtering), our method performs better in terms of the signal-to-error ratio, the computational burden (0.125 seconds for one minute of DVP signal analysis with the Intel Core 2 Quad processor @ 2.40 GHz PC), the true detection rate (97.32% with an acceptance level of 4 ms ) as well as the normalized error rate (0.18%). In addition, the proposed method can detect true positions of pulse peaks more accurately and becomes very useful for pulse transit time (PTT) and pulse rate variability (PRV) analyses.

  15. Temporal pulse shaping: a key parameter for the laser welding of dental alloys.

    Science.gov (United States)

    Bertrand, Caroline; Poulon-Quintin, Angeline

    2015-07-01

    This study aims to describe the effect of pulse shaping on the prevention of internal defects during laser welding for two dental alloys mainly used in prosthetic dentistry. Single spot, weld beads, and welds with 80 % overlapping were performed on Co-Cr-Mo and Pd-Ag-Sn cast plates with a pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. A specific welding procedure using adapted parameters to each alloy was completed. All the possibilities for pulse shaping were tested: (1) the square pulse shape as a default setting, (2) a rising edge slope for gradual heating, (3) a falling edge slope to slow the cooling process, and (4) a combination of rising and falling edges. The optimization of the pulse shape is supposed to produce defect-free welds (crack, pores, voids). Cross-section SEM observations and Vickers microhardness measurements were made. Pd-Ag-Sn was highly sensitive to hot cracking, and Co-Cr-Mo was more sensitive to voids and small porosities (sometimes combined with cracks). Using a slow cooling ramp allowed a better control on the solidification process for those two alloys always preventing internal defects. A rapid slope should be preferred for Co-Cr-Mo alloys due to its low-laser beam reflectivity. On the opposite, for Pd-Ag-Sn alloy, a slow rising slope should be preferred because this alloy has a high-laser beam reflectivity.

  16. Pulse shaping and energy storage capabilities of angularly multiplexed KrF laser fusion drivers

    Science.gov (United States)

    Lehmberg, R. H.; Giuliani, J. L.; Schmitt, A. J.

    2009-07-01

    This paper describes a rep-rated multibeam KrF laser driver design for the 500kJ Inertial Fusion test Facility (FTF) recently proposed by NRL, then models its optical pulse shaping capabilities using the ORESTES laser kinetics code. It describes a stable and reliable iteration technique for calculating the required precompensated input pulse shape that will achieve the desired output shape, even when the amplifiers are heavily saturated. It also describes how this precompensation technique could be experimentally implemented in real time on a reprated laser system. The simulations show that this multibeam system can achieve a high fidelity pulse shaping capability, even for a high gain shock ignition pulse whose final spike requires output intensities much higher than the ˜4MW/cm2 saturation levels associated with quasi-cw operation; i.e., they show that KrF can act as a storage medium even for pulsewidths of ˜1ns. For the chosen pulse, which gives a predicted fusion energy gain of ˜120, the simulations predict the FTF can deliver a total on-target energy of 428kJ, a peak spike power of 385TW, and amplified spontaneous emission prepulse contrast ratios IASE/Ilaser.

  17. Enhancement of Time Reversal Sub-wavelength Wireless Transmission Using Pulse Shaping Technique (submit/1139227)

    CERN Document Server

    Ding, Shuai; Zang, Rui; Zou, Lianfeng; Wang, Bing-Zhong; Caloz, Christophe

    2014-01-01

    A novel time-reversal subwavelength transmission technique, based on pulse shaping circuits (PSCs), is proposed. This technique removes the need for complex or electrically large electromagnetic structures by generating channel diversity via pulse shaping instead of angular spectrum transformation. It is shown that, compared to our previous time-reversal system based on chirped delay lines, the PSC approach offers greater flexibility and larger possible numbers of channels, i.e. ultimately higher transmission throughput. The PSC based time-reversal system is also demonstrated experimentally.

  18. Application of the Recursive Subtraction Pulse Shape Analysis algorithm to in-beam HPGe signals

    Energy Technology Data Exchange (ETDEWEB)

    Crespi, F.C.L. [Dipartimento di Fisica, Universita di Milano and INFN Sezione di Milano, Via Celoria 16, 20133 Milano (Italy); Camera, F. [Dipartimento di Fisica, Universita di Milano and INFN Sezione di Milano, Via Celoria 16, 20133 Milano (Italy)], E-mail: camera@mi.infn.it; Bracco, A.; Million, B.; Wieland, O.; Vandone, V. [Dipartimento di Fisica, Universita di Milano and INFN Sezione di Milano, Via Celoria 16, 20133 Milano (Italy); Recchia, F.; Gadea, A.; Kroell, Th. [Laboratori Nazionali di Legnaro, INFN, Viale dell' Universita 2, 35020 Legnaro, Padova (Italy); Mengoni, D.; Farnea, E.; Ur, C.A.; Bazzacco, D. [Dipartimento di Fisica, Universita di Padova and INFN Sezione di Padova, Via Marzolo 8, 35131 Padova (Italy)

    2009-06-11

    The Pulse Shape Analysis algorithm 'Recursive Subtraction' has been applied to data acquired during the in-beam tests of two different highly segmented HPGe detectors. This algorithm processes the net charge signal, determining the number of interactions per segment and their radial coordinates. The RS algorithm performances are evaluated by comparing the results obtained following its application to experimental pulse shapes with those obtained with specific GEANT simulations. Excellent agreement is found between the experimental distribution of the number of interactions per segment and the simulated one. Deviations between experimental radial distribution and the calculated ones are discussed.

  19. Design of one-dimensional optical pulse-shaping filters by time-domain topology optimization

    DEFF Research Database (Denmark)

    Yang, Lirong; Lavrinenko, Andrei; Hvam, Jørn Märcher

    2009-01-01

    Time-domain topology optimization is used here to design optical pulse-shaping filters in Si/SiO2 thin-film systems. A novel envelope objective function as well as explicit penalization are used to adapt the optimization method to this unique class of design problems.......Time-domain topology optimization is used here to design optical pulse-shaping filters in Si/SiO2 thin-film systems. A novel envelope objective function as well as explicit penalization are used to adapt the optimization method to this unique class of design problems....

  20. PERFORMANCE STUDIES OF CDZNTE DETECTOR BY USING A PULSE SHAPE ANALYSIS.

    Energy Technology Data Exchange (ETDEWEB)

    BOLOTNIKOV, A.

    2005-07-31

    Pulse shape analysis is proved to be a powerful tool to characterize the performance of CdZnTe devices and understand their operating principles. It allows one to investigate the device configurations, electron transport properties, effects governing charge collection, electric-field distributions, signal charge formation, etc. This work describes an application of different techniques based on the pulse shape measurements to characterize pixel, coplanar-grid, and virtual Frisch-grid devices and understand the electronic properties of CZT material provided by different vendors. We report new results that may explain the performance limits of these devices.

  1. Synthesis of fractal light pulses by quasi-direct space-to-time pulse shaping.

    Science.gov (United States)

    Mendoza-Yero, Omel; Alonso, Benjamín; Mínguez-Vega, Gladys; Sola, Iñigo Juan; Lancis, Jesús; Monsoriu, Juan A

    2012-04-01

    We demonstrated a simple diffractive method to map the self-similar structure shown in squared radial coordinate of any set of circularly symmetric fractal plates into self-similar light pulses in the corresponding temporal domain. The space-to-time mapping of the plates was carried out by means of a kinoform diffractive lens under femtosecond illumination. The spatio-temporal characteristics of the fractal pulses obtained in this way were measured by means of a spectral interferometry technique assisted by a fiber optics coupler (STARFISH). Our proposal allows synthesizing suited sequences of focused fractal femtosecond pulses potentially useful for several current applications, such as femtosecond material processing, atomic, and molecular control of chemical processes or generation of nonlinear effects.

  2. High Resolution Mode-Selective Excitation by Adaptive Femtosecond Pulse Shaping

    Institute of Scientific and Technical Information of China (English)

    LI Xia; ZHANG Hui; ZHANG Xiang-Yun; ZHANG Shi-An; CHEN Guo-Liang; WANG Zu-Geng; SUN Zhen-Rong

    2008-01-01

    High resolution mode-selective excitation in the mixture of C6H6(992cm-1)and C6D6(945cm-1)is experimentally achieved by adaptive femtosecond pulse shaping based on the genetic algorithm(GA),and second harmonic generation frequency-resolved optical gating(SHG-FROG)is adopted to characterize the original and optimal laser pulses,and its mechanism is experimentally validated by tailoring the frequency components of the pump pulses at the Fourier plane.It is indicated that two-pulse coherent mode-selective excitation of the Raman scattering mainly depends on the effective frequency components of the pump pulse related to specific molecular vibrational mode.The experimental results have attractive potential appfications in the complicated molecular system.

  3. Numerical analysis of transient keyhole shape in pulsed current plasma arc welding

    Institute of Scientific and Technical Information of China (English)

    孙俊华; 武传松

    2014-01-01

    Based on the characteristics of“one keyhole in a pulse”in pulsed current plasma arc welding (PAW),the transient variation process ofweld pool in a pulse cycle is simulated through the establishment ofcorresponding heat source model.And considering the effects ofgravitational force,plasma arc pressure and surface tension on the weld pool surface,the dynamic change features of the keyhole shape in a pulse cycle are calculated by using surface deformation equation. Experiments are conducted and validate that the calculated weld fusion line is in good agreement with the experimental results.

  4. Modeling the Pulse Signal by Wave-Shape Function and Analyzing by Synchrosqueezing Transform.

    Directory of Open Access Journals (Sweden)

    Hau-Tieng Wu

    Full Text Available We apply the recently developed adaptive non-harmonic model based on the wave-shape function, as well as the time-frequency analysis tool called synchrosqueezing transform (SST to model and analyze oscillatory physiological signals. To demonstrate how the model and algorithm work, we apply them to study the pulse wave signal. By extracting features called the spectral pulse signature, and based on functional regression, we characterize the hemodynamics from the radial pulse wave signals recorded by the sphygmomanometer. Analysis results suggest the potential of the proposed signal processing approach to extract health-related hemodynamics features.

  5. Pulse shaping in mode-locked fiber lasers by in-cavity spectral filter.

    Science.gov (United States)

    Boscolo, Sonia; Finot, Christophe; Karakuzu, Huseyin; Petropoulos, Periklis

    2014-02-01

    We numerically show the possibility of pulse shaping in a passively mode-locked fiber laser by inclusion of a spectral filter into the laser cavity. Depending on the amplitude transfer function of the filter, we are able to achieve various regimes of advanced temporal waveform generation, including ones featuring bright and dark parabolic-, flat-top-, triangular- and saw-tooth-profiled pulses. The results demonstrate the strong potential of an in-cavity spectral pulse shaper for controlling the dynamics of mode-locked fiber lasers.

  6. Pulse re-shaping by using a liquid crystal spatial light modulator and deflector for producing a specific waveform

    Institute of Scientific and Technical Information of China (English)

    Jun Kang; Wei Zhang; Hui Wei; Shaohe Chen; Jianqiang Zhu

    2006-01-01

    @@ A new shaping method for producing nanosecond pulses with specific shape is introduced. When a Gaussian laser pulse passes through an electro-optic deflector, it has been scanned as a line on the focal plane according to time precedence. Through controlling the intensity of transmitted light on each pixel of the liquid crystal spatial light modulator (LCSLM), various complicated pulses can be easily produced. Using this method, various specific shaped pulses with pulse duration varying from 750 ps to 5 ns are achieved.

  7. Assessment of pulse height selection methods for several spectrum shapes in radiation detection

    Energy Technology Data Exchange (ETDEWEB)

    Mainardi, Raul T. E-mail: mainardi@famaf.unc.edu.ar; Plivelic, Tomas S. E-mail: tomas@lnls.br; Derosa, Pedro A. E-mail: derosa@engr.sc.edu

    2003-03-01

    The minimum pulse height selection method developed more than forty years ago to process the information provided by detectors with an energy spectrum responding to a Landau distribution is extended in this work to consider other information processing criteria such as the maximum pulse height and the pulse height closest to the mode. The latter is a selection method whereby the mode is calculated for a distribution and then, a pulse closest to it is selected from a given set and stored. We analyze the combined resolution of a set of identical sampling detectors in terms of the number of detectors and the shape of the characteristic pulse height distribution from a single detector. To make this treatment as general as possible, five analytical forms are tested as symmetric and asymmetric pulse height distributions, applying to each of them the three selection methods mentioned above. We also compare these results with the average of the pulse heights in each case. For these evaluations, analytical calculations and Monte Carlo simulations were carried out. It was thus possible to select the most appropriate selection method based on the shape parameters of a distribution.

  8. The influence of size and shape of microorganism on pulsed electric field inactivation.

    Science.gov (United States)

    El-Hag, Ayman H; Jayaram, Shesha H; Gonzalez, Oscar Rodriguez; Griffiths, M W

    2011-09-01

    In this paper the effect of microorganism size and shape on the killing efficiency of pulsed electric field (PEF) is investigated both experimentally and using a transient finite element program. The effect of cell size, membrane thickness, cell shape (spherical, elliptical, and cylindrical) on the calculated transmembrane voltage is studied. It has been found that both the cell size and cell membrane thickness have significant effect on the induced field across the cell membrane. The findings of the simulation results have been evaluated by comparing the trends with some experimental results. Five different types of microorganisms that have different shapes and dimensions have been inoculated with water at a conductivity level of 100 μS/cm and have been treated with the application of a pulsed electric field of 70 kV/cm. Significant difference in bacteria reduction was noticed between the treated cells which could be attributed to the cell size and shape.

  9. Photonic multi-shape UWB pulse generation using a semiconductor optical amplifier-based nonlinear optical loop mirror

    Institute of Scientific and Technical Information of China (English)

    Luo Bo-Wen; Dong Jian-Ji; Yu Yuan; Yang Ting; Zhang Xin-Liang

    2013-01-01

    We propose and demonstrate a scheme to implement photonic multi-shape ultra-wideband (UWB) signal generation using a semiconductor optical amplifier (SOA) based nonlinear optical loop mirror (NOLM).By employing the cross phase modulation (XPM) effect,cross gain modulation (XGM),or both,multi-shape UWB waveforms are generated including monocycle,doublet,triplet,and quadruplet pulses.Both the shapes and polarities of the generated pulses are flexible to adjust,which may be very useful in UWB pulse shape modulation and pulse polarity modulation.

  10. Context dependent digital shape editing in product design

    NARCIS (Netherlands)

    Dumitrescu, R.

    2007-01-01

    The present CAID systems insufficiently support designers with effective and intuitive tools for shape modelling. Designers' efficiency significantly decreases when shape alterations are performed. The research described in this thesis deals with the development of a methodology to support more effe

  11. A new digital pulse power supply in heavy ion research facility in Lanzhou

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Rongkun, E-mail: wangrongkun@impcas.ac.cn [Institute of Modern Physics, Lanzhou, 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Chen, Youxin; Huang, Yuzhen; Gao, Daqing; Zhou, Zhongzu; Yan, Huaihai [Institute of Modern Physics, Lanzhou, 730000 (China); Zhao, Jiang; Shi, Chunfeng; Wu, Fengjun [Institute of Modern Physics, Lanzhou, 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Yan, Hongbin; Xia, Jiawen; Yuan, Youjin [Institute of Modern Physics, Lanzhou, 730000 (China)

    2013-11-01

    To meet the increasing requirements of the Heavy Ion Research Facility in Lanzhou-Cooler Storage Ring (HIRFL-CSR), a new digital pulse power supply, which employs multi-level converter, was designed. This power supply was applied with a multi H-bridge converters series-parallel connection topology. A new control model named digital power supply regulator system (DPSRS) was proposed, and a pulse power supply prototype based on DPSRS has been built and tested. The experimental results indicate that tracking error and ripple current meet the requirements of this design. The achievement of prototype provides a perfect model for HIRFL-CSR power supply system. -- Highlights: • The converters topology of series-parallel connection improves the power supply's performance. • The SOPC based on dual Nios II processors improves the real-time performance of system. • Pulse mode is implemented in digital power supply based on FPGA, with a smaller tracking error.

  12. Digital pressure ulcer after pulse oximetry [Digitales Druckulkus nach Pulsoxymetrie

    Directory of Open Access Journals (Sweden)

    Zeplin, Philip H.

    2013-06-01

    Full Text Available [english] In emergency medical service, in intensive care unit and anaesthesia oxygenation is monitored with pulse oximetry apparatus. Pulse oximetry probe is usually attached to the finger, toe or earlobe. To the best of our knowledge this is the first case report describing the occurrence of a pressure ulcer after finger pulse oximetry measurement.[german] Sowohl in der Notfall- und Intensivmedizin als auch in der Anästhesie wird die Sauerstoffsättigung des Blutes mit Pulsoxymetern ermittelt. Diese Pulsoxymeter werden üblicherweise an den Fingern, den Zehen oder dem Ohrläppchen angebracht. Wir beschreiben einen Fall, bei dem es nach Anlage eines Fingerclip-Pulsoxymeters zur Ausbildung eines operationsbedürftigen Druckulkus kam.

  13. A new digital pulse power supply in heavy ion research facility in Lanzhou

    Science.gov (United States)

    Wang, Rongkun; Chen, Youxin; Huang, Yuzhen; Gao, Daqing; Zhou, Zhongzu; Yan, Huaihai; Zhao, Jiang; Shi, Chunfeng; Wu, Fengjun; Yan, Hongbin; Xia, Jiawen; Yuan, Youjin

    2013-11-01

    To meet the increasing requirements of the Heavy Ion Research Facility in Lanzhou-Cooler Storage Ring (HIRFL-CSR), a new digital pulse power supply, which employs multi-level converter, was designed. This power supply was applied with a multi H-bridge converters series-parallel connection topology. A new control model named digital power supply regulator system (DPSRS) was proposed, and a pulse power supply prototype based on DPSRS has been built and tested. The experimental results indicate that tracking error and ripple current meet the requirements of this design. The achievement of prototype provides a perfect model for HIRFL-CSR power supply system.

  14. Evaluation of pulsed RFI effects on digital satellite repeaters

    Science.gov (United States)

    Huang, T. C.; Braun, W. R.

    1980-01-01

    This paper presents an analytical approach for assessing the effect of pulsed RFI on the error probability of a coherent phase-shift keyed signal through a nonlinear satellite repeater. The RFI is assumed to affect the uplink channel and to consist of CW pulses with random power levels and arriving randomly in time with a Poisson distribution. A model to approximate the effect of intermodulation products is introduced and the error probability conditioned on the output of the satellite repeater is computed. The classical moment technique is then used as an efficient method of averaging the conditional error probability over the numerous random parameters associated with the uplink signal.

  15. Simultaneous SU(2) rotations on multiple quantum dot exciton qubits using a single shaped pulse

    Science.gov (United States)

    Mathew, Reuble; Yang, Hong Yi Shi; Hall, Kimberley C.

    2015-10-01

    Recent experimental demonstration of a parallel (π ,2 π ) single qubit rotation on excitons in two distant quantum dots [Nano Lett. 13, 4666 (2013), 10.1021/nl4018176] is extended in numerical simulations to the design of pulses for more general quantum state control, demonstrating the feasibility of full SU(2) rotations of each exciton qubit. Our results show that simultaneous high-fidelity quantum control is achievable within the experimentally accessible parameter space for commercial Fourier-domain pulse shaping systems. The identification of a threshold of distinguishability for the two quantum dots (QDs) for achieving high-fidelity parallel rotations, corresponding to a difference in transition energies of ˜0.25 meV , points to the possibility of controlling more than 10 QDs with a single shaped optical pulse.

  16. Full-density, net-shape powder consolidation using dynamic magnetic pulse pressures

    Science.gov (United States)

    Chelluri, Bhanu; Barber, John P.

    1999-07-01

    The full-density consolidation of powders into net-shape parts yields high green strength, low shrinkage, short sinter times, superior mechanical properties, and low manufacturing costs. The conventional lowcost, single-press, single-sinter process typically densifies powders at less than 65 percent green density. This article describes the Magnepress™ process, a powder-processing technique wherein pulsed magnetic pressures consolidate powders into full-density parts without admixed lubricants or binders. The Magnepress technique is especially suitable for producing net-shape products with radial symmetry (e.g., rods, cylindrical parts with internal features, tubular shapes, and high aspect-ratio specimens).

  17. Spatially resolved measurements and diagnostics of digitally controlled rotating field pulsed plasma operated in helium at 20 kHz

    Science.gov (United States)

    Giersz, Jacek; Jankowski, Krzysztof; Reszke, Edward

    2017-04-01

    Using optical emission spectrometry, fundamental properties are investigated of a stable, planar atmospheric pressure micro discharge, several dozen microliters in volume, driven by a digitally controlled 20 kHz rotating microsecond pulsed power. The discharge is generated by rectangular wave pulses using helium as the working gas. At a low cost, the digitally controlled plasma source produces a highly symmetrical, non-stationary helium discharge maintained in open air within 5 electrodes positioned in the plane toward the center. It has been shown that the geometrical shapes of the momentary discharges, which occur between the electrodes, are not arc-like shaped, but rather have a diffusive character and the resulting plasma can become doughnut-like in shape. Rotational and vibrational temperatures from OH and N2 bands, excitation temperatures from He lines and ionization temperatures from Ca lines, as well as electron number densities from Hβ Stark broadening have been estimated along the plasma diameter using axial viewing. The results demonstrated that Texc (He) reaches stable value of 3800 K for selected plasma generation conditions (one anode and two cathodes commutation mode, cathode pulse width 8 microseconds, supplied power 200 W, helium gas flow 1 L·min- 1), while the Trot (OH) is considerably lower (1700 K). The electron number density has been evaluated to be (1.7-3.3) × 1014 cm- 3 and both Tion (Ca) and Tvib (N2) varied, throughout in the 4500-5100 K and 4000-4800 K ranges respectively, reaching its peak value near 2 mm off the plasma axis. Spatial measurements revealed symmetrical distribution of the plasma parameters, while the measurements of calcium and nitrogen ionic emission confirmed symmetrical doughnut shape of the discharge. Moreover, the processes running inside the discharge and their interaction with the surrounding atmosphere have been described in accordance to the recorded spectra. Spectroscopic observation has shown the existence of

  18. Pulse Decomposition Analysis of the digital arterial pulse during hemorrhage simulation

    Science.gov (United States)

    2011-01-01

    Background Markers of temporal changes in central blood volume are required to non-invasively detect hemorrhage and the onset of hemorrhagic shock. Recent work suggests that pulse pressure may be such a marker. A new approach to tracking blood pressure, and pulse pressure specifically is presented that is based on a new form of pulse pressure wave analysis called Pulse Decomposition Analysis (PDA). The premise of the PDA model is that the peripheral arterial pressure pulse is a superposition of five individual component pressure pulses, the first of which is due to the left ventricular ejection from the heart while the remaining component pressure pulses are reflections and re-reflections that originate from only two reflection sites within the central arteries. The hypothesis examined here is that the PDA parameter T13, the timing delay between the first and third component pulses, correlates with pulse pressure. T13 was monitored along with blood pressure, as determined by an automatic cuff and another continuous blood pressure monitor, during the course of lower body negative pressure (LBNP) sessions involving four stages, -15 mmHg, -30 mmHg, -45 mmHg, and -60 mmHg, in fifteen subjects (average age: 24.4 years, SD: 3.0 years; average height: 168.6 cm, SD: 8.0 cm; average weight: 64.0 kg, SD: 9.1 kg). Results Statistically significant correlations between T13 and pulse pressure as well as the ability of T13 to resolve the effects of different LBNP stages were established. Experimental T13 values were compared with predictions of the PDA model. These interventions resulted in pulse pressure changes of up to 7.8 mmHg (SE = 3.49 mmHg) as determined by the automatic cuff. Corresponding changes in T13 were a shortening by -72 milliseconds (SE = 4.17 milliseconds). In contrast to the other two methodologies, T13 was able to resolve the effects of the two least negative pressure stages with significance set at p arterial pressure pulse reflections. The proposed physical

  19. Reducing error rates in straintronic multiferroic nanomagnetic logic by pulse shaping.

    Science.gov (United States)

    Munira, Kamaram; Xie, Yunkun; Nadri, Souheil; Forgues, Mark B; Fashami, Mohammad Salehi; Atulasimha, Jayasimha; Bandyopadhyay, Supriyo; Ghosh, Avik W

    2015-06-19

    Dipole-coupled nanomagnetic logic (NML), where nanomagnets (NMs) with bistable magnetization states act as binary switches and information is transferred between them via dipole-coupling and Bennett clocking, is a potential replacement for conventional transistor logic since magnets dissipate less energy than transistors when they switch in a logic circuit. Magnets are also 'non-volatile' and hence can store the results of a computation after the computation is over, thereby doubling as both logic and memory-a feat that transistors cannot achieve. However, dipole-coupled NML is much more error-prone than transistor logic at room temperature [Formula: see text] because thermal noise can easily disrupt magnetization dynamics. Here, we study a particularly energy-efficient version of dipole-coupled NML known as straintronic multiferroic logic (SML) where magnets are clocked/switched with electrically generated mechanical strain. By appropriately 'shaping' the voltage pulse that generates strain, we show that the error rate in SML can be reduced to tolerable limits. We describe the error probabilities associated with various stress pulse shapes and discuss the trade-off between error rate and switching speed in SML.The lowest error probability is obtained when a 'shaped' high voltage pulse is applied to strain the output NM followed by a low voltage pulse. The high voltage pulse quickly rotates the output magnet's magnetization by 90° and aligns it roughly along the minor (or hard) axis of the NM. Next, the low voltage pulse produces the critical strain to overcome the shape anisotropy energy barrier in the NM and produce a monostable potential energy profile in the presence of dipole coupling from the neighboring NM. The magnetization of the output NM then migrates to the global energy minimum in this monostable profile and completes a 180° rotation (magnetization flip) with high likelihood.

  20. Optical parametric chirped pulse amplification and spectral shaping of a continuum generated in a photonic band gap fiber.

    Science.gov (United States)

    Hugonnot, E; Somekh, M; Villate, D; Salin, F; Freysz, E

    2004-05-31

    A chirped pulse, spectrally broadened in a photonic bandgap optical fiber by 120 fs Ti:Sapphire laser pulses, is parametrically amplified in a BBO crystal pumped by a frequency doubled nanosecond Nd:YAG laser pulse. Without changing the frequency of the Ti:Sapphire, a spectral tunability of the amplified pulses is demonstrated. The possibility to achieve broader spectral range amplification is confirmed for a non-collinear pump-signal interaction geometry. For optimal non-collinear interaction geometry, the pulse duration of the original and amplified pulse are similar. Finally, we demonstrate that the combination of two BBO crystals makes it possible to spectrally shape the amplified pulses.

  1. On the applicability of arbitrarily shaped nanosecond laser pulses for high-quality, high-efficiency micromachining

    Science.gov (United States)

    Eiselen, Sasia; Riedel, Sebastian; Schmidt, Michael

    2014-05-01

    Progressive developments in temporal shaping of short laser pulses offer entirely new approaches at influence and investigate laser-matter-interactions. Commonly used parameters for describing the behavior of short or ultrashort pulses or pulse trains are fluence and intensity. However, fluence does not imply any information about the temporal behavior of energy input during specific pulse duration τ while using the pulse intensity as describing parameter is more meaningful. Nevertheless it still is an averaging over pulse duration and no change in intensity can be determined if the temporal pulse shape changes within a certain combination of pulse duration and pulse energy. Using a flexible programmable MOPA fiber laser experimental studies on the impact of temporal energy distribution within one single laser pulse in micro machining applications were therefore carried out. With this laser source a direct modulation of the temporal pulse shape in the nanosecond regime can easily be controlled. Experiments were carried out with moved as well as with un-moved beam resulting in areas and dimples respectively drilling holes. The presented results clearly show that any averaging over pulse duration results in missing information about time-dependent interactions but can at the same time lead to significant differences in ablation results. Thus, resulting surface roughness Sa can be decreased up to 25 % when changing the pulse shape at constant parameters of fluence and pulse peak power at a pulse duration of 30 ns. It can be observed that the combination of an intensity peak and a lower edge within one pulse can lead to increasing ablation efficiency as well as higher ablation quality compared to the commonly used Gaussian-like temporal pulse shape.

  2. Wave-shaping of pulse tube cryocooler components for improved performance

    Science.gov (United States)

    Antao, Dion Savio; Farouk, Bakhtier

    2014-11-01

    The method of wave-shaping acoustic resonators is applied to an inertance type cryogenic pulse tube refrigerator (IPTR) to improve its performance. A detailed time-dependent axisymmetric experimentally validated computational fluid dynamic (CFD) model of the PTR is used to predict its performance. The continuity, momentum and energy equations are solved for both the refrigerant gas (helium) and the porous media regions (the regenerator and the three heat-exchangers) in the PTR. An improved representation of heat transfer in the porous media is achieved by employing a thermal non-equilibrium model to couple the gas and solid (porous media) energy equations. The wave-shaped regenerator and pulse tube studied have cone geometries and the effects of different cone angles and the orientation (nozzle v/s diffuser mode) on the system performance are investigated. The resultant spatio-temporal pressure, temperature and velocity fields in the regenerator and pulse tube components are evaluated. The performance of these wave-shaped PTRs is compared to the performance of a non wave-shaped system with cylindrical components. Better cooling is predicted for the cryocooler using wave-shaped components oriented in the diffuser mode.

  3. Spectro-temporal shaping of seeded free-electron laser pulses

    CERN Document Server

    Gauthier, David; De Ninno, Giovanni; Allaria, Enrico; Cinquegrana, Paolo; Danailov, Miltcho Boyanov; Demidovich, Alexander; Ferrari, Eugenio; Giannessi, Luca; Mahieu, Benoît; Penco, Giuseppe

    2015-01-01

    We demonstrate the ability to control and shape the spectro-temporal content of extreme-ultraviolet (XUV) pulses produced by a seeded free-electron laser (FEL). The control over the spectro-temporal properties of XUV light was achieved by precisely manipulating the linear frequency chirp of the seed laser. Our results agree with existing theory, which allows retrieving the temporal properties (amplitude and phase) of the FEL pulse from measurements of the spectra as a function of the FEL operating parameters. Furthermore, we show the first direct evidence of the full temporal coherence of FEL light and generate Fourier limited pulses by fine-tuning the FEL temporal phase. The possibility to tailor the spectro-temporal content of intense short-wavelength pulses represents the first step towards efficient nonlinear optics in the XUV to X-ray spectral region and will enable precise manipulation of core-electron excitations using the methods of coherent quantum control.

  4. Device for measurement of power and shape of radio frequency pulses in nuclear magnetic resonance

    Science.gov (United States)

    Pfeffer, M.; Řezníček, R.; Křišťan, P.; Štěpánková, H.

    2012-05-01

    A design of an instrument to measure the power and shape of radio frequency (RF) pulses operating in a broad frequency range is described. The device is capable of measuring the pulse power up to 500 W of both CW and extremely short (˜1 μs) RF pulses of arbitrary period. The pulse envelope can be observed on a logarithmic scale on a corresponding instrument output using an inexpensive storage oscilloscope. The instrument consists of a coaxial measurement head, the RF processing circuits and an AD conversion and display unit. The whole device is based on widely available integrated circuits; thus, good reproducibility and adaptability of the design is ensured. Since the construction is intended to be used in particular (but not solely) in nuclear magnetic resonance spectroscopy, we found it useful to provide a demonstration of two typical usage scenarios. Other application fields may comprise magnetic resonance imaging, radar and laser technology, power amplifier testing, etc.

  5. A high fidelity Rydberg blockade entangling gate using shaped, analytic pulses

    CERN Document Server

    Theis, L S; Wilhelm, F K; Saffmann, M

    2016-01-01

    We show that the use of shaped pulses improves the fidelity of a Rydberg blockade two-qubit entangling gate by several orders of magnitude compared to previous protocols based on square pulses or optimal control pulses. Using analytical Derivative Removal by Adiabatic Gate (DRAG) pulses that reduce excitation of primary leakage states and an analytical method of finding the optimal Rydberg blockade we generate Bell states with a fidelity of $F>0.9999$ in a 300 K environment for a gate time of only $50\\;{\\rm ns}$, which is an order of magnitude faster than previous protocols. These results establish the potential of neutral atom qubits with Rydberg blockade gates for scalable quantum computation.

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

    Science.gov (United States)

    Warburton, William K [Menlo Park, CA

    2008-03-11

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

  7. Incoherent frequency-to-time mapping: application to incoherent pulse shaping.

    Science.gov (United States)

    Torres-Company, Victor; Lancis, Jesús; Andrés, Pedro

    2007-03-01

    After temporal amplitude modulation of a spectrally incoherent optical source the averaged intensity profile at the so-called temporal far-zone regime coalesces with a magnified replica of the spectral density function of the source. This has provided the basis for the generalization of the frequency-to-time mapping technique in the partially coherent case. Based on this fact, temporal intensity waveform generation is demonstrated by spectral filtering the incoherent source before the temporal modulation stage. We refer to this technique as full incoherent pulse shaping. Although only the average intensity of the output signal is properly shaped, intensity fluctuations between the different realizations of the output shaped waveform are shown to be small in the practical situation. Finally, we provide some computer simulations concerning arbitrary picosecond pulse generation from an amplified spontaneous emission source.

  8. Quantum phase amplification for temporal pulse shaping and super-resolution in remote sensing

    Science.gov (United States)

    Yin, Yanchun

    The use of nonlinear optical interactions to perform nonclassical transformations of electromagnetic field is an area of considerable interest. Quantum phase amplification (QPA) has been previously proposed as a method to perform nonclassical manipulation of coherent light, which can be experimentally realized by use of nonlinear optical mixing processes, of which phase-sensitive three-wave mixing (PSTWM) is one convenient choice. QPA occurs when PSTWM is operated in the photon number deamplification mode, i.e., when the energy is coherently transferred among the low-frequency signal and idler waves and the high-frequency pump wave. The final state is nonclassical, with the field amplitude squeezed and the phase anti-squeezed. In the temporal domain, the use of QPA has been studied to facilitate nonlinear pulse shaping. This novel method directly shapes the temporal electric field amplitude and phase using the PSTWM in a degenerate and collinear configuration, which has been analyzed using a numerical model. Several representative pulse shaping capabilities of this technique have been identified, which can augment the performance of common passive pulse shaping methods operating in the Fourier domain. The analysis indicates that a simple quadratic variation of temporal phase facilitates pulse compression and self-steepening, with features significantly shorter than the original transform-limited pulse. Thus, PSTWM can act as a direct pulse compressor based on the combined effects of phase amplification and group velocity mismatch, even without the subsequent linear phase compensation. Furthermore, it is shown numerically that pulse doublets and pulse trains can be produced at the pump frequency by utilizing the residual linear phase of the signal. Such pulse shaping capabilities are found to be within reach of this technique in common nonlinear optical crystals pumped by pulses available from compact femtosecond chirped-pulse amplification laser systems. The use of

  9. Digital generation of shape-invariant Bessel-like beams.

    Science.gov (United States)

    Litvin, Igor A; Mhlanga, Thandeka; Forbes, Andrew

    2015-03-23

    Bessel beams have been extensive studied to date but are always created over a finite region inside the laboratory. Means to overcome this consider multi-element refractive designs to create beams that have a longitudinal dependent cone angle, thereby allowing for a far greater quasi non-diffracting propagation region. Here we outline a generalized approach for the creation of shape-invariant Bessel-like beams with a single phase-only element, and demonstrate it experimentally with a phase-only spatial light modulator. Our experimental results are in excellent agreement with theory, suggesting an easy-to-implement approach for long range, shape-invariant Bessel-like beams.

  10. Development of high sensitivity 4H-SiC detectors for fission neutron pulse shape measurements.

    Science.gov (United States)

    Wu, Jian; Jiang, Yong; Li, Meng; Zeng, Lina; Li, Junjie; Gao, Hui; Zou, Dehui; Bai, Zhongxiong; Ye, Cenming; Liang, Wenfeng; Dai, Shaofeng; Lu, Yi; Rong, Ru; Du, Jinfeng; Fan, Xiaoqiang

    2017-08-01

    4H-silicon carbide (4H-SiC) detectors are well suited for measurements of fission neutron pulse shape for their compact size, excellent radiation resistance, and hydrogen free composition. The aim of this study is to improve the 4H-SiC detector's sensitivity to fission neutron pulses. 4H-SiC detectors with varied epilayer thicknesses are fabricated and then tested in the pulsed neutron field of the Chinese Fast Burst Reactor II (CFBR II). The sensitivity of the 4H-SiC detector to the CFBR II neutron pulse is increased by 139.8%, with the enlargement of epilayer thickness from 20 μm to 120 μm. By employing the proton-recoil method, the sensitivity of the 4H-SiC detector to the CFBR II neutron pulse is further increased by 11.6%. With enhanced sensitivity to fission neutron pulses, 4H-SiC detectors are promising devices for high intensity neutron pulse measurements.

  11. Simultaneous ultrafast optical pulse train bursts generation and shaping based on Fourier series developments using superimposed fiber Bragg gratings.

    Science.gov (United States)

    García-Muñoz, Víctor; Preciado, Miguel A; Muriel, Miguel A

    2007-08-20

    We propose an all-fiber method for the generation of ultrafast shaped pulse train bursts from a single pulse based on Fourier Series Developments (FDSs). The implementation of the FSD based filter only requires the use of a very simple non apodized Superimposed Fiber Bragg Grating (S-FBG) for the generation of the Shaped Output Pulse Train Burst (SOPTB). In this approach, the shape, the period and the temporal length of the generated SOPTB have no dependency on the input pulse rate.

  12. Toward a fractal spectrum approach for neutron and gamma pulse shape discrimination

    Science.gov (United States)

    Liu, Ming-Zhe; Liu, Bing-Qi; Zuo, Zhuo; Wang, Lei; Zan, Gui-Bin; Tuo, Xian-Guo

    2016-06-01

    Accurately selecting neutron signals and discriminating γ signals from a mixed radiation field is a key research issue in neutron detection. This paper proposes a fractal spectrum discrimination approach by means of different spectral characteristics of neutrons and γ rays. Figure of merit and average discriminant error ratio are used together to evaluate the discrimination effects. Different neutron and γ signals with various noise and pulse pile-up are simulated according to real data in the literature. The proposed approach is compared with the digital charge integration and pulse gradient methods. It is found that the fractal approach exhibits the best discrimination performance, followed by the digital charge integration method and the pulse gradient method, respectively. The fractal spectrum approach is not sensitive to high frequency noise and pulse pile-up. This means that the proposed approach has superior performance for effective and efficient anti-noise and high discrimination in neutron detection. Supported by the National Natural Science Foundation of China (41274109), Sichuan Youth Science and Technology Innovation Research Team (2015TD0020), Scientific and Technological Support Program of Sichuan Province (2013FZ0022), and the Creative Team Program of Chengdu University of Technology.

  13. Scaling single-wavelength optical interconnects to 180 Gb/s with PAM-M and pulse shaping

    Science.gov (United States)

    Dris, Stefanos; Bakopoulos, Paraskevas; Argyris, Nikolaos; Spatharakis, Christos; Avramopoulos, Hercules

    2016-03-01

    Faced with surging datacenter traffic demand, system designers are turning to multi-level optical modulation with direct detection as the means of reaching 100 Gb/s in a single optical lane; a further upgrade to 400 Gb/s is envisaged through wavelength-multiplexing of multiple 100 Gb/s strands. In terms of modulation formats, PAM-4 and PAM-8 are considered the front-runners, striking a good balance between bandwidth-efficiency and implementation complexity. In addition, the emergence of energy-efficient, high-speed CMOS digital-to-analog converters (DACs) opens up new possibilities: Spectral shaping through digital filtering will allow squeezing even more data through low-cost, low-bandwidth electro-optic components. In this work we demonstrate an optical interconnect based on an EAM that is driven directly with sub-volt electrical swing by a 65 GSa/s arbitrary waveform generator (AWG). Low-voltage drive is particularly attractive since it allows direct interfacing with the switch/server ASIC, eliminating the need for dedicated, power-hungry and expensive electrical drivers. Single-wavelength throughputs of 180 and 120 Gb/s are experimentally demonstrated with 60 Gbaud optical PAM-8 and PAM-4 respectively. Successful transmission over 1250 m SMF is achieved with direct-detection, using linear equalization via offline digital signal processing in order to overcome the strong bandwidth limitation of the overall link (~20 GHz). The suitability of Nyquist pulse shaping for optical interconnects is also investigated experimentally with PAM-4 and PAM-8, at a lower symbol rate of 40 Gbaud (limited by the sampling rate of the AWG). To the best of our knowledge, the rates achieved are the highest ever using optical PAM-M formats.

  14. Numerical Analysis of the Output-Pulse Shaping Capability of Linear Transformer Drivers

    Science.gov (United States)

    Liu, Peng; Sun, Fengju; Yin, Jiahui; Qiu, Aici

    2011-04-01

    Output-pulse shaping capability of a linear transformer driver (LTD) module under different conditions is studied, by conducting the whole circuit model simulation by using the PSPICE code. Results indicate that a higher impedance profile of the internal transmission line would lead to a wider adjustment range for the output current rise time and a narrower adjustment range for the current peak. The number of cavities in series has a positive effect on the output-pulse shaping capability of LTD. Such an improvement in the output-pulse shaping capability can primarily be ascribed to the increment in the axial electric length of LTD. For a triggering time interval longer than the time taken by a pulse to propagate through the length of one cavity, the output parameters of LTD could be improved significantly. The present insulating capability of gas switches and other elements in the LTD cavities may only tolerate a slightly longer deviation in the triggering time interval. It is feasible for the LTD module to reduce the output current rise time, though it is not useful to improve the peak power effectively.

  15. Laser induced forward transfer of metals by temporally shaped femtosecond laser pulses.

    Science.gov (United States)

    Klini, A; Loukakos, P A; Gray, D; Manousaki, A; Fotakis, C

    2008-07-21

    Temporally shaped, femtosecond laser pulses have been used for controlling the size and the morphology of micron-sized metallic structures obtained by using the Laser Induced Forward Transfer (LIFT) technique. We report the effect of pulse shaping on the size and morphology of the deposited structures of Au, Zn, Cr on a function of the pulse separation time ??t (from 0 to 10 ps) of double pulses of variable intensities generated by using a liquid crystal spatial light modulator (SLM). The observed differences in size and morphology are correlated with the outcome of pump-probe experiments for the study of electron-phonon scattering dynamics and subsequent energy transfer processes to the bulk in the different metals employed. We propose that in metals with weak electron-lattice coupling, the electron ballistic motion and the resulting fast electron scattering at the film surface, as well as the internal electron thermalization process are crucial to the morphology and size of the transferred material. Therefore, temporal shaping within the corresponding time scales of these processes may be used for tailoring the features of the metallic structures obtained by LIFT.

  16. An Approach to 3d Digital Modeling of Surfaces with Poor Texture by Range Imaging Techniques. `SHAPE from Stereo' VS. `SHAPE from Silhouette' in Digitizing Jorge Oteiza's Sculptures

    Science.gov (United States)

    García Fernández, J.; Álvaro Tordesillas, A.; Barba, S.

    2015-02-01

    Despite eminent development of digital range imaging techniques, difficulties persist in the virtualization of objects with poor radiometric information, in other words, objects consisting of homogeneous colours (totally white, black, etc.), repetitive patterns, translucence, or materials with specular reflection. This is the case for much of the Jorge Oteiza's works, particularly in the sculpture collection of the Museo Fundación Jorge Oteiza (Navarra, Spain). The present study intend to analyse and asses the performance of two digital 3D-modeling methods based on imaging techniques, facing cultural heritage in singular cases, determined by radiometric characteristics as mentioned: Shape from Silhouette and Shape from Stereo. On the other hand, the text proposes the definition of a documentation workflow and presents the results of its application in the collection of sculptures created by Oteiza.

  17. Complexity and simplicity of optimal control theory pulses shaped for controlling vibrational qubits.

    Science.gov (United States)

    Shyshlov, Dmytro; Babikov, Dmitri

    2012-11-21

    In the context of molecular quantum computation the optimal control theory (OCT) is used to obtain shaped laser pulses for high-fidelity control of vibrational qubits. Optimization is done in time domain and the OCT algorithm varies values of electric field in each time step independently, tuning hundreds of thousands of parameters to find one optimal solution. Such flexibility is not available in experiments, where pulse shaping is done in frequency domain and the number of "tuning knobs" is much smaller. The question of possible experimental interpretations of theoretically found OCT solutions arises. In this work we analyze very accurate optimal pulse that we obtained for implementing quantum gate CNOT for the two-qubit system encoded into the exited vibrational states of thiophosgene molecule. Next, we try to alter this pulse by reducing the number of available frequency channels and intentionally introducing systematic and random errors (in frequency domain, by modifying the values of amplitudes and phases of different frequency components). We conclude that a very limited number of frequency components (only 32 in the model of thiophosgene) are really necessary for accurate control of the vibrational two-qubit system, and such pulses can be readily constructed using OCT. If the amplitude and phase errors of different frequency components do not exceed ±3% of the optimal values, one can still achieve accurate transformations of the vibrational two-qubit system, with gate fidelity of CNOT exceeding 0.99.

  18. Measurement of (222)Rn by absorption in plastic scintillators and alpha/beta pulse shape discrimination.

    Science.gov (United States)

    Mitev, Krasimir K

    2016-04-01

    This work demonstrates that common plastic scintillators like BC-400, EJ-200 and SCSF-81 absorb radon and their scintillation pulse decay times are different for alpha- and beta-particles. This allows the application of pulse shape analysis for separation of the pulses of alpha- and beta-particles emitted by the absorbed radon and its progeny. It is shown that after pulse shape discrimination of beta-particles' pulses, the energy resolution of BC-400 and EJ-200 alpha spectra is sufficient to separate the peaks of (222)Rn, (218)Po and (214)Po and allows (222)Rn measurements that are unaffected by the presence of thoron ((220)Rn) in the environment. The alpha energy resolution of SCSF-81 in the experiments degrades due to imperfect collection of the light emitted inside the scintillating fibers. The experiments with plastic scintillation microspheres (PSM) confirm previous findings of other researchers that PSM have alpha-/beta-discrimination properties and show suitability for radon measurements. The diffusion length of radon in BC-400 and EJ-200 is determined. The pilot experiments show that the plastic scintillators are suitable for radon-in-soil-gas measurements. Overall, the results of this work suggest that it is possible to develop a new type of radon measurement instruments which employ absorption in plastic scintillators, pulse-shape discrimination and analysis of the alpha spectra. Such instruments can be very compact and can perform continuous, real-time radon measurements and thoron detection. They can find applications in various fields from radiation protection to earth sciences. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Design of a Tunable All-Digital UWB Pulse Generator CMOS Chip for Wireless Endoscope.

    Science.gov (United States)

    Chul Kim; Nooshabadi, S

    2010-04-01

    A novel tunable all-digital, ultrawideband pulse generator (PG) has been implemented in a standard 0.18-¿ m complementary metal-oxide semiconductor (CMOS) process for implantable medical applications. The chip shows that an ultra-low dynamic energy consumption of 27 pJ per pulse without static current flow at a 200-MHz pulse repetition frequency (PRF) with a 1.8-V power supply and low area of 90 × 50 ¿m(2). The PG generates tunable pulsewidth, amplitude, and transmit (Tx) power by using simple circuitry, through precise timing control of the H-bridge output stage. The all-digital architecture allows easy integration into a standard CMOS process, thus making it the most suitable candidate for in-vivo biotelemetry applications.

  20. The Technology and Properties of Digital Double Pulse Electrodepositing Ni-HA Composite Coating of Bioceramics

    Institute of Scientific and Technical Information of China (English)

    DONG He-yan; WANG Zhou; SHI Gu-guizhi; FU Chuan-qi; CHEN Wei-rong; JIN Zhong-hong; LI Yan

    2004-01-01

    This article discusses and analyses the technology, the surface image, microstructure and ability of digital double pulse electrodepositing Ni-HA composite coatings of bioceramics made on 1Crl8Ni9Ti substrate by SEM ,XRD and so on. The results shows that ( 1 ) the HA particles exit in substrate uniformly; (2) XRD result shows that there are HA peaks at 78. 023 ° ,43. 246°and 73. 120°differently; (3) The microhardnees of the composite coatings is increased with the rise of content of HA particles, and on the same conditions the microhardnees value is greater than that of common non-pulse electrodepositing Ni-HA composite coatings of bioceramics. (4) The grain size of digital double pulse electrodepositing Ni-HA composite coatings of bioceramics is much thinner than that of common D. C.

  1. Pulsed digital micro-holography of femto-second order by double-wavelength recording

    Institute of Scientific and Technical Information of China (English)

    WANG Ming-wei; WANG Xiao-lei; ZHAI Hong-chen

    2007-01-01

    Double-wavelength recording used in a pulsed digital micro-holographic system to record ultra-fast processing of the order of femto-second is reported for the first time, where a BBO crystal is used to generate harmonic wave of the incident laser wave, and both of the basic and the frequency doubled waves are time-delayed and introduced to a Michelson's interferom eter to record two sub-holograms with different spatial frequencies on a single frame of a CCD. In the experiment, an ultra fast dynamic process of air ionization induced by a single femto-second laser pulse is recorded with holography by this system, and both of intensity and phase difference images digitally reconstructed are obtained through Fourier transformation and digital filtering, which show clearly the dynamic process of formation and propagation of the plasma, with a time resolution of the order of femto-second.

  2. A novel technique for the characterization of a HPGe detector response based on pulse shape comparison

    Energy Technology Data Exchange (ETDEWEB)

    Crespi, F.C.L. [Dipartimento di Fisica, Universita di Milano and INFN Sezione di Milano, Via Celoria 16, 20133 Milano (Italy); Camera, F. [Dipartimento di Fisica, Universita di Milano and INFN Sezione di Milano, Via Celoria 16, 20133 Milano (Italy)], E-mail: camera@mi.infn.it; Million, B.; Sassi, M.; Wieland, O.; Bracco, A. [Dipartimento di Fisica, Universita di Milano and INFN Sezione di Milano, Via Celoria 16, 20133 Milano (Italy)

    2008-08-11

    A novel technique for measuring the HPGe detector pulse shape as a function of the {gamma}-ray interaction position inside the detector volume is presented. This technique is based on a specific pulse shape comparison procedure. Its main feature is that it allows to characterize the 3D position response of a HPGe segmented detector in a much shorter time as compared with the standard coincidence techniques. The method was first validated using a GEANT simulation of a 36-fold HPGe AGATA detector realized taking into account the effects of the electronic chain response and electrical noise on the calculated signal shape. This procedure was then applied to extract experimentally the position response of a non-segmented coaxial HPGe detector along the radial direction, using a 438 MBq {sup 137}Cs collimated {gamma}-source. The results of this measurement show a dependence of the pulse shape as a function of {gamma}-ray interaction radial coordinate consistent with that obtained with calculations. The signal acquisition rate reached using this characterization technique allows to realize a full scan of a large volume highly segmented HPGe detector in less than a week.

  3. Digital pulse processing and optimization of the front-end electronics for nuclear instrumentation.

    Science.gov (United States)

    Bobin, C; Bouchard, J; Thiam, C; Ménesguen, Y

    2014-05-01

    This article describes an algorithm developed for the digital processing of signals provided by a high-efficiency well-type NaI(Tl) detector used to apply the 4πγ technique. In order to achieve a low-energy threshold, a new front-end electronics has been specifically designed to optimize the coupling to an analog-to-digital converter (14 bit, 125 MHz) connected to a digital development kit produced by Altera(®). The digital pulse processing is based on an IIR (Infinite Impulse Response) approximation of the Gaussian filter (and its derivatives) that can be applied to the real-time processing of digitized signals. Based on measurements obtained with the photon emissions generated by an (241)Am source, the energy threshold is estimated to be equal to ~2 keV corresponding to the physical threshold of the NaI(Tl) detector. An algorithm developed for a Silicon Drift Detector used for low-energy x-ray spectrometry is also described. In that case, the digital pulse processing is specifically designed for signals provided by a reset-type preamplifier ((55)Fe source).

  4. Analysis of the hole shape evolution in fs-pulse percussion drilling with bursts

    Science.gov (United States)

    Kämmer, H.; Dreisow, F.; Tünnermann, A.; Nolte, Stefan

    2016-03-01

    We analyze the use of bursts of ultra-short pulses in order to improve drilling efficiency and quality. Silicon is used as a non-transparent model material, in which the behavior of laser percussion drilling with 1030 nm bursts consisting of 200 fs pulses separated by a time delay between 1 ps and 4 ns was investigated. The deep drilling process is directly imaged perpendicular to the drilling direction using a CCD camera and an illumination beam at 1064 nm, where the silicon sample is transparent. The results are compared to drilling without bursts for different pulse energies. The efficiency of the drilling process, hole quality, as well as reproducibility of the hole shape are analyzed. Pulse separation times within the burst from 1 ps to 8 ps result in deeper holes with a larger silhouette area, however equal or reduced hole quality and reproducibility compared to drilling with individual pulses. In contrast with pulse separation times from 510 ps to 4 ns a quality and reproducibility improvement is visible. For these delay times the achieved depth was equal or higher compared to micromachining without bursts.

  5. Pulse wave velocity and digital volume pulse as indirect estimators of blood pressure: pilot study on healthy volunteers.

    Science.gov (United States)

    Padilla, Juan M; Berjano, Enrique J; Sáiz, Javier; Rodriguez, Rafael; Fácila, Lorenzo

    2009-09-01

    The purpose of the study was to asses the potential use of pulse wave velocity (PWV) and digital volume pulse (DVP) as estimators of systolic (SBP) and diastolic (DPB) blood pressure. Single and multiple correlation studies were conducted, including biometric parameters and risk factors. Brachial-ankle PWV (baPWV) and DVP signals were obtained from a Pulse Trace PWV and Pulse Trace PCA (pulse contour analysis), respectively. The DVP (obtained by photoplethysmography), allowed stiffness (SI) and reflection indexes (RI) to be derived. The first study on 47 healthy volunteers showed that both SBP and DPB correlated significantly both with baPWV and SI. Multiple regression models of the baPWV and the waist-to-hip ratio (WHR) allowed SBP and DBP to be modeled with r = 0.838 and r = 0.673, respectively. SI results also employed WHR and modeled SBP and DBP with r = 0.852 and r = 0.663, respectively. RI did not correlate either with SBP or DBP. In order to avoid the use of ultrasound techniques to measure PWV, we then developed a custom-built system to measure PWV by photoplethysmography and validated it against the Pulse Trace. With the same equipment we conducted a second pilot study with ten healthy volunteers. The best SBP multiple regression model for SBP achieved r = 0.997 by considering the heart-finger PWV (hfPWV measured between R-wave and index finger), WHR and heart rate. Only WHR was significant in the DBP model. Our findings suggest that the hfPWV photoplethysmography signal could be a reliable estimator of approximate SBP and could be used, for example, to monitor cardiac patients during physical exercise sessions in cardiac rehabilitation.

  6. Interactive generation of digital anthropomorphic phantoms from XCAT shape priors

    Science.gov (United States)

    Lindsay, C.; Gennert, M. A.; Connolly, C. M.; Konik, A.; Dasari, P. K.; Segars, W. P.; King, M. A.

    2012-03-01

    In SPECT imaging, patient respiratory and body motion can cause artifacts that degrade image quality. Developing and evaluating motion correction algorithms are facilitated by simulation studies where a numerical phantom and its motion are precisely known, from which image data can be produced. Previous techniques to test motion correction methods generated XCAT phantoms modeled from MRI studies and motion tracking but required manually segmenting the major structures within the whole upper torso, which can take 8 hours to perform. Additionally, segmentation in two dimensional MRI slices and interpolating into three dimensional shapes can lead to appreciable interpolation artifacts as well as requiring expert knowledge of human anatomy in order to identify the regions to be segmented within each slice. We propose a new method that mitigates the long manual segmentation times for segmenting the upper torso. Our interactive method requires that a user provide only an approximate alignment of the base anatomical shapes from the XCAT model with an MRI data. Organ boundaries from aligned XCAT models are warped with displacement fields generated from registering a baseline MR image to MR images acquired during pre-determined motions, which amounts to automated segmentation each organ of interest. With our method we can show the quality of segmentation is equal that of expert manual segmentation does not require a user who is an expert in anatomy, and can be completed in minutes not hours. In some instances, due to interpolation artifacts, our method can generate higher quality models than manual segmentation.

  7. Pulse-shape analysis for gamma background rejection in thermal neutron radiation using CVD diamond detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kavrigin, P., E-mail: pavel.kavrigin@cividec.at [Vienna University of Technology (Austria); Finocchiaro, P., E-mail: finocchiaro@lns.infn.it [INFN Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Griesmayer, E., E-mail: erich.griesmayer@cividec.at [Vienna University of Technology (Austria); Jericha, E., E-mail: jericha@ati.ac.at [Vienna University of Technology (Austria); Pappalardo, A., E-mail: apappalardo@lns.infn.it [INFN Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Weiss, C., E-mail: Christina.Weiss@cern.ch [Vienna University of Technology (Austria); European Organisation for Nuclear Research (CERN), Geneva (Switzerland)

    2015-09-21

    A novel technique for the rejection of gamma background from charged-particle spectra was demonstrated using a CVD diamond detector with a {sup 6}Li neutron converter installed at a thermal neutron beamline of the TRIGA research reactor at the Atominstitut (Vienna University of Technology). Spectra of the alpha particles and tritons of {sup 6}Li(n,T){sup 4}He thermal neutron capture reaction were separated from the gamma background by a new algorithm based on pulse-shape analysis. The thermal neutron capture in {sup 6}Li is already used for neutron flux monitoring, but the ability to remove gamma background allows using a CVD diamond detector for thermal neutron counting. The pulse-shape analysis can equally be applied to all cases where the charged products of an interaction are absorbed in the diamond and to other background particles that fully traverse the detector.

  8. Pulse-shape discrimination with PbWO$_4$ crystal scintillators

    CERN Document Server

    Bardelli, L; Bizzeti, P G; Danevich, F A; Fazzini, T F; Kobychev, V V; Krutyak, N; Maurenzig, P R; Mokina, V M; Nagorny, S S; Pashkovskii, M; Poda, D V; Tretyak, V I; Yurchenko, S S

    2007-01-01

    The light output, $\\alpha/\\beta$ ratio, and pulse shape have been investigated at $-25^\\circ$ C with PbWO$_4$ crystal scintillators undoped, and doped by F, Eu, Mo, Gd and S. The fast $0.01-0.06 \\mu$s and middle $0.1-0.5 \\mu$s components of scintillation decay were observed for all the samples. Slow components of scintillation signal with the decay times $1-3 \\mu$s and $13-28 \\mu$s with the total intensity up to $\\approx50%$ have been recognized for several samples doped by Molybdenum. We found some indications of a pulse-shape discrimination between $\\alpha$ particles and $\\gamma$ quanta with PbWO$_4$ (Mo doped) crystal scintillators.

  9. Pulse-shape discrimination with PbWO{sub 4} crystal scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Bardelli, L.; Bini, M.; Bizzeti, P.G. [Dipartimento di Fisica, Universita di Firenze and INFN, 50019 Florence (Italy); Danevich, F.A. [Institute for Nuclear Research, Prospect Nauki 47, MSP 03680 Kyiv (Ukraine)], E-mail: danevich@kinr.kiev.ua; Fazzini, T.F. [Dipartimento di Fisica, Universita di Firenze and INFN, 50019 Florence (Italy); Krutyak, N. [Skobeltsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Vorob' evy Gory, 119992 Moscow (Russian Federation); Kobychev, V.V. [Institute for Nuclear Research, Prospect Nauki 47, MSP 03680 Kyiv (Ukraine); Maurenzig, P.R. [Dipartimento di Fisica, Universita di Firenze and INFN, 50019 Florence (Italy); Mokina, V.M.; Nagorny, S.S. [Institute for Nuclear Research, Prospect Nauki 47, MSP 03680 Kyiv (Ukraine); Pashkovskii, M. [Department of Semiconductors Physics, Ivan Franko National University, UA-79005 Lviv (Ukraine); Poda, D.V.; Tretyak, V.I.; Yurchenko, S.S. [Institute for Nuclear Research, Prospect Nauki 47, MSP 03680 Kyiv (Ukraine)

    2008-01-01

    Light output, {alpha}/{beta} ratio, and pulse shape have been investigated at -25 deg. C with PbWO{sub 4} crystal scintillators undoped, and doped by F, Eu, Mo, Gd and S. The fast 0.01-0.06{mu}s and middle 0.1-0.5{mu}s components of scintillation decay were observed for all the samples. Slow components of scintillation signal with decay times 1-3 and 13-28{mu}s with total intensity up to {approx}50% have been recognized for several samples doped by Molybdenum. We found some indications of a pulse-shape discrimination between {alpha} particles and {gamma} quanta with PbWO{sub 4} (Mo doped) crystal scintillators.

  10. Annular shape silver lined proportional counter for on-line pulsed neutron yield measurement

    Science.gov (United States)

    Dighe, P. M.; Das, D.

    2015-04-01

    An annular shape silver lined proportional counter is developed to measure pulsed neutron radiation. The detector has 314 mm overall length and 235 mm overall diameter. The central cavity of 150 mm diameter and 200 mm length is used for placing the neutron source. Because of annular shape the detector covers >3π solid angle of the source. The detector has all welded construction. The detector is developed in two halves for easy mounting and demounting. Each half is an independent detector. Both the halves together give single neutron pulse calibration constant of 4.5×104 neutrons/shot count. The detector operates in proportional mode which gives enhanced working conditions in terms of dead time and operating range compared to Geiger Muller based neutron detectors.

  11. Wavelength effect on hole shapes and morphology evolution during ablation by picosecond laser pulses

    Science.gov (United States)

    Zhao, Wanqin; Wang, Wenjun; Li, Ben Q.; Jiang, Gedong; Mei, Xuesong

    2016-10-01

    An experimental study is presented of the effect of wavelength on the shape and morphology evolution of micro holes ablated on stainless steel surface by a 10 ps Q-switched Nd:VAN pulsed laser. Two routes of hole development are associated with the visible (532 nm) and near-infrared (1064 nm) laser beams, respectively. The evolution of various geometric shapes and morphological characteristics of the micro holes ablated with the two different wavelengths is comparatively studied for other given processing conditions such as a laser power levels and the number of pulses applied. Plausible explanations, based on the light-materials interaction associated with laser micromachining, are also provided for the discernable paths of geometric and morphological development of holes under laser ablation.

  12. Coherent Control of Multiphoton Transitions in the Gas and Condensed Phases with Shaped Ultrashort Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Marcos Dantus

    2008-09-23

    Controlling laser-molecule interactions has become an integral part of developing devices and applications in spectroscopy, microscopy, optical switching, micromachining and photochemistry. Coherent control of multiphoton transitions could bring a significant improvement of these methods. In microscopy, multi-photon transitions are used to activate different contrast agents and suppress background fluorescence; coherent control could generate selective probe excitation. In photochemistry, different dissociative states are accessed through two, three, or more photon transitions; coherent control could be used to select the reaction pathway and therefore the yield-specific products. For micromachining and processing a wide variety of materials, femtosecond lasers are now used routinely. Understanding the interactions between the intense femtosecond pulse and the material could lead to technologically important advances. Pulse shaping could then be used to optimize the desired outcome. The scope of our research program is to develop robust and efficient strategies to control nonlinear laser-matter interactions using ultrashort shaped pulses in gas and condensed phases. Our systematic research has led to significant developments in a number of areas relevant to the AMO Physics group at DOE, among them: generation of ultrashort phase shaped pulses, coherent control and manipulation of quantum mechanical states in gas and condensed phases, behavior of isolated molecules under intense laser fields, behavior of condensed phase matter under intense laser field and implications on micromachining with ultrashort pulses, coherent control of nanoparticles their surface plasmon waves and their nonlinear optical behavior, and observation of coherent Coulomb explosion processes at 10^16 W/cm^2. In all, the research has resulted in 36 publications (five journal covers) and nine invention disclosures, five of which have continued on to patenting

  13. Flexible radio-frequency photonics: Optoelectronic frequency combs and integrated pulse shaping

    Science.gov (United States)

    Metcalf, Andrew J.

    Microwave photonics is a discipline which leverages optoelectronics to enhance the generation, transport, and processing of high-frequency electrical signals. At the heart of many emerging techniques is the optical frequency comb. A comb is a lightwave source whose spectrum is made up of discrete equally spaced spectral components that share a fixed phase relationship. These discrete coherent oscillators --known as comb lines-- collectively form a Fourier basis that describe a periodic optical waveform. Within the last two decades frequency-stabilized broadband combs produced from mode-locked lasers have led to revolutionary advancements in precision optical frequency synthesis and metrology. Meanwhile, Fourier-transform optical pulse shaping, which provides a means to control a comb's Fourier basis in both amplitude and phase, has emerged as an integral tool in optical communications, broadband waveform generation, and microwave photonic filtering. However, traditional comb and pulse shaping architectures are often plagued by complex and bulky setups, rendering robust and cost effective implementation outside of the laboratory a challenge. In addition, traditional comb sources based on short-pulse lasers do not possess qualities which are ideally suited for this new application regime. Motivated by the shortcomings in current architectures, and empowered by recent advancements in optoelectronic technology, this dissertation focuses on developing novel and robust schemes in optical frequency comb generation and line-by-line pulse shaping. Our results include: the invention and low-noise characterization of a broadband flat-top comb source; the realization of an optoelectronic-based time cloak; and finally, the development of an integrated pulse shaper, which we use in conjunction with our flat-top comb source to demonstrate a rapidly reconfigurable microwave photonic filter.

  14. Pulsed high field magnets. An efficient way of shaping laser accelerated proton beams for application

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, Florian; Schramm, Ulrich [Helmholtz-Zentrum Dresden - Rossendorf, 01328 Dresden (Germany); Technische Universitaet Dresden, 01062 Dresden (Germany); Bagnoud, Vincent; Blazevic, Abel; Busold, Simon [GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Helmholtz Institut Jena, 07734 Jena (Germany); Brabetz, Christian; Schumacher, Dennis [GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Deppert, Oliver; Jahn, Diana; Roth, Markus [Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Karsch, Leonhard; Masood, Umar [OncoRay-National Center for Radiation Research in Oncology, TU Dresden, 01307 Dresden (Germany); Kraft, Stephan [Helmholtz-Zentrum Dresden - Rossendorf, 01328 Dresden (Germany)

    2015-07-01

    Compact laser-driven proton accelerators are a potential alternative to complex, expensive conventional accelerators, enabling unique beam properties, like ultra-high pulse dose. Nevertheless, they still require substantial development in reliable beam generation and transport. We present experimental studies on capture, shape and transport of laser and conventionally accelerated protons via pulsed high-field magnets. These magnets, common research tools in the fields of solid state physics, have been adapted to meet the demands of laser acceleration experiments.Our work distinctively shows that pulsed magnet technology makes laser acceleration more suitable for application and can facilitate compact and efficient accelerators, e.g. for material research as well as medical and biological purposes.

  15. Multibeam second-harmonic generation by spatiotemporal shaping of femtosecond pulses.

    Science.gov (United States)

    Martínez-Cuenca, Raúl; Mendoza-Yero, Omel; Alonso, Benjamín; Sola, Íñigo Juan; Mínguez-Vega, Gladys; Lancis, Jesús

    2012-03-01

    We present a technique for efficient generation of the second-harmonic signal at several points of a nonlinear crystal simultaneously. Multispot operation is performed by using a diffractive optical element that splits the near-infrared light of a mode-locked Ti:sapphire laser into an arbitrary array of beams that are transformed into an array of foci at the nonlinear crystal. We show that, for pulse temporal durations under 100 fs, spatiotemporal shaping of the pulse is mandatory to overcome chromatic dispersion effects that spread both in space and time the foci showing a reduced peak intensity that prevents nonlinear phenomena. We experimentally demonstrate arbitrary irradiance patterns for the second-harmonic signal consisting of more than 100 spots with a multipass amplifier delivering 28 fs, 0.8 mJ pulses at 1 kHz repetition rate.

  16. Femtosecond pulse shaping as analytic tool in mass spectrometry of complex polyatomic systems

    Science.gov (United States)

    Laarmann, Tim; Shchatsinin, Ihar; Singh, Pushkar; Zhavoronkov, Nickolai; Schulz, Claus Peter; Hertel, Ingolf Volker

    2008-04-01

    An additional dimension to mass spectrometric studies on building blocks of proteins is discussed in this paper. The present approach is based on tailored femtosecond laser pulses, using the concept of strong-field pulse shaping in an adaptive feedback loop. We show that control strategies making use of coherent properties of the electromagnetic wave allow one to break pre-selected backbone bonds in amino acid complexes that may be regarded as peptide model systems. Studies on different chromophores, such as phenylalanine and alanine, while keeping the backbone structure unchanged elucidates the effect of the excitation dynamics on the relaxation pathways. The observation of protonated species in the corresponding mass spectra indicates that optimal control of ultrafast laser pulses may even be useful to study intramolecular reactions such as hydrogen- or proton-transfer in particular cases. This opens new perspectives for biophysical and biochemical research, since these photochemical reactions are suggested to explain, e.g. photostability of DNA.

  17. Pulse Shape Discrimination in liquid argon and its implications for Dark Matter searches using depleted argon

    CERN Document Server

    Kryczynski, Pawel

    2012-01-01

    A brief outline of Dark Matter detection experiments using liquid argon technology is presented. The Pulse Shape background discrimination method (PSD) is described and the example of its use in 2.3 l R&D detector is given. Methods of calculating sensitivity of a Dark Matter detector are discussed and used to estimate the possible improvement of sensitivity after introduction of isotopically depleted liquid argon.

  18. Optimization of ultra-fast interactions using laser pulse temporal shaping controlled by a deterministic algorithm

    Science.gov (United States)

    Galvan-Sosa, M.; Portilla, J.; Hernandez-Rueda, J.; Siegel, J.; Moreno, L.; Ruiz de la Cruz, A.; Solis, J.

    2014-02-01

    Femtosecond laser pulse temporal shaping techniques have led to important advances in different research fields like photochemistry, laser physics, non-linear optics, biology, or materials processing. This success is partly related to the use of optimal control algorithms. Due to the high dimensionality of the solution and control spaces, evolutionary algorithms are extensively applied and, among them, genetic ones have reached the status of a standard adaptive strategy. Still, their use is normally accompanied by a reduction of the problem complexity by different modalities of parameterization of the spectral phase. Exploiting Rabitz and co-authors' ideas about the topology of quantum landscapes, in this work we analyze the optimization of two different problems under a deterministic approach, using a multiple one-dimensional search (MODS) algorithm. In the first case we explore the determination of the optimal phase mask required for generating arbitrary temporal pulse shapes and compare the performance of the MODS algorithm to the standard iterative Gerchberg-Saxton algorithm. Based on the good performance achieved, the same method has been applied for optimizing two-photon absorption starting from temporally broadened laser pulses, or from laser pulses temporally and spectrally distorted by non-linear absorption in air, obtaining similarly good results which confirm the validity of the deterministic search approach.

  19. Compartment shape anisotropy (CSA) revealed by double pulsed field gradient MR.

    Science.gov (United States)

    Ozarslan, Evren

    2009-07-01

    The multiple scattering extensions of the pulsed field gradient (PFG) experiments can be used to characterize restriction-induced anisotropy at different length scales. In double-PFG acquisitions that involve two pairs of diffusion gradient pulses, the dependence of the MR signal attenuation on the angle between the two gradients is a signature of restriction that can be observed even at low gradient strengths. In this article, a comprehensive theoretical treatment of the double-PFG observation of restricted diffusion is presented. In the first part of the article, the problem is treated for arbitrarily shaped pores under idealized experimental conditions, comprising infinitesimally narrow gradient pulses with long separation times and long or vanishing mixing times. New insights are obtained when the treatment is applied to simple pore shapes of spheres, ellipsoids, and capped cylinders. The capped cylinder geometry is considered in the second part of the article where the solution for a double-PFG experiment with arbitrary experimental parameters is introduced. Although compartment shape anisotropy (CSA) is emphasized here, the findings of this article can be used in gleaning the volume, eccentricity, and orientation distribution function associated with ensembles of anisotropic compartments using double-PFG acquisitions with arbitrary experimental parameters.

  20. Micro drilling using deformable mirror for beam shaping of ultra-short laser pulses

    Science.gov (United States)

    Smarra, Marco; Strube, Anja; Dickmann, Klaus

    2016-03-01

    Using ultra-short laser pulses for micro structuring or drilling applications reduces the thermal influence to the surrounding material. The best achievable beam profile equals a Gaussian beam. Drilling with this beam profile results in cylindrical holes. To vary the shape of the holes, the beam can either be scanned or - for single pulse and percussion drilling - manipulated by masks or lenses. A high flexible method for beam shaping can be realized by using a deformable mirror. This mirror contains a piezo-electric ceramic, which can be deformed by an electric potential. By separating the ceramic into independent controllable segments, the shape of the surface can be varied individually. Due to the closed surface of the mirror, there is no loss of intensity due to diffraction. The mirror deformation is controlled by Zernike polynomials and results e.g. in a lens behavior. In this study a deformable mirror was used to generate e.g. slits in thin steel foils by percussion drilling using ultra-short laser pulses. The influence of the cylindrical deformation to the laser beam and the resulting geometry of the generated holes was studied. It was demonstrated that due to the high update rate up to 150 Hz the mirror surface can be varied in each scan cycle, which results in a high flexible drilling process.

  1. Nanosecond Pulse Shaping with Fiber-Based Electro-Optical Modulators and a Double-Pass Tapered Amplifier

    CERN Document Server

    Rogers, Charles E

    2015-01-01

    We describe a system for generating frequency-chirped and amplitude-shaped pulses on time scales from sub-nanosecond to ten nanoseconds. The system starts with cw diode-laser light at 780 nm and utilizes fiber-based electro-optical phase and intensity modulators, driven by an arbitrary waveform generator, to generate the shaped pulses. These pulses are subsequently amplified to several hundred mW with a tapered amplifier in a delayed double-pass configuration. Frequency chirps up to 5 GHz in 2 ns and pulse widths as short as 0.15 ns have been realized.

  2. BEBE(tr) and BUBI: J-compensated concurrent shaped pulses for 1H-13C experiments.

    Science.gov (United States)

    Ehni, Sebastian; Luy, Burkhard

    2013-07-01

    Shaped pulses designed for broadband excitation, inversion and refocusing are important tools in modern NMR spectroscopy to achieve robust pulse sequences especially in heteronuclear correlation experiments. A large variety of mostly computer-optimized pulse shapes exist for different desired bandwidths, available rf-field strengths, and tolerance to B1-inhomogeneity. They are usually derived for a single spin 1/2, neglecting evolution due to J-couplings. While pulses with constant resulting phase are selfcompensated for heteronuclear coupling evolution as long as they are applied exclusively on a single nucleus, the situation changes for concurrently applied pulse shapes. Using the example of a (1)H,(13)C two spin system, two J-compensated pulse pairs for the application in INEPT-type transfer elements were optimized: a point-to-point pulse sandwich called BEBE(tr), consisting of a broadband excitation and time-reversed excitation pulse, and a combined universal rotation and point-to-point pulse pair called BUBI, which acts as a refocusing pulse on (1)H and a corresponding inversion pulse on (13)C. After a derivation of quality factors and optimization protocols, a theoretical and experimental comparison with conventionally derived BEBOP, BIBOP, and BURBOP-180° pulses is given. While the overall transfer efficiency of a single pulse pair is only reduced by approximately 0.1%, resulting transfer to undesired coherences is reduced by several percent. In experiments this can lead to undesired phase distortions for pairs of uncompensated pulse shapes and even differences in signal intensities of 5-10% in HSQC and up to 68% in more complex COB-HSQC experiments.

  3. The Influence of Vesicle Shape and Medium Conductivity on Possible Electrofusion under a Pulsed Electric Field.

    Directory of Open Access Journals (Sweden)

    Linying Liu

    Full Text Available The effects of electric field on lipid membrane and cells have been extensively studied in the last decades. The phenomena of electroporation and electrofusion are of particular interest due to their wide use in cell biology and biotechnology. However, numerical studies on the electrofusion of cells (or vesicles with different deformed shapes are still rare. Vesicle, being of cell size, can be treated as a simple model of cell to investigate the behaviors of cell in electric field. Based on the finite element method, we investigate the effect of vesicle shape on electrofusion of contact vesicles in various medium conditions. The transmembrane voltage (TMV and pore density induced by a pulsed field are examined to analyze the possibility of vesicle fusion. In two different medium conditions, the prolate shape is observed to have selective electroporation at the contact area of vesicles when the exterior conductivity is smaller than the interior one; selective electroporation is more inclined to be found at the poles of the oblate vesicles when the exterior conductivity is larger than the interior one. Furthermore, we find that when the exterior conductivity is lower than the internal conductivity, the pulse can induce a selective electroporation at the contact area between two vesicles regardless of the vesicle shape. Both of these two findings have important practical applications in guiding electrofusion experiments.

  4. The Influence of Vesicle Shape and Medium Conductivity on Possible Electrofusion under a Pulsed Electric Field.

    Science.gov (United States)

    Liu, Linying; Mao, Zheng; Zhang, Jianhua; Liu, Na; Liu, Qing Huo

    2016-01-01

    The effects of electric field on lipid membrane and cells have been extensively studied in the last decades. The phenomena of electroporation and electrofusion are of particular interest due to their wide use in cell biology and biotechnology. However, numerical studies on the electrofusion of cells (or vesicles) with different deformed shapes are still rare. Vesicle, being of cell size, can be treated as a simple model of cell to investigate the behaviors of cell in electric field. Based on the finite element method, we investigate the effect of vesicle shape on electrofusion of contact vesicles in various medium conditions. The transmembrane voltage (TMV) and pore density induced by a pulsed field are examined to analyze the possibility of vesicle fusion. In two different medium conditions, the prolate shape is observed to have selective electroporation at the contact area of vesicles when the exterior conductivity is smaller than the interior one; selective electroporation is more inclined to be found at the poles of the oblate vesicles when the exterior conductivity is larger than the interior one. Furthermore, we find that when the exterior conductivity is lower than the internal conductivity, the pulse can induce a selective electroporation at the contact area between two vesicles regardless of the vesicle shape. Both of these two findings have important practical applications in guiding electrofusion experiments.

  5. The Influence of Vesicle Shape and Medium Conductivity on Possible Electrofusion under a Pulsed Electric Field

    Science.gov (United States)

    Liu, Linying; Mao, Zheng; Zhang, Jianhua; Liu, Na; Liu, Qing Huo

    2016-01-01

    The effects of electric field on lipid membrane and cells have been extensively studied in the last decades. The phenomena of electroporation and electrofusion are of particular interest due to their wide use in cell biology and biotechnology. However, numerical studies on the electrofusion of cells (or vesicles) with different deformed shapes are still rare. Vesicle, being of cell size, can be treated as a simple model of cell to investigate the behaviors of cell in electric field. Based on the finite element method, we investigate the effect of vesicle shape on electrofusion of contact vesicles in various medium conditions. The transmembrane voltage (TMV) and pore density induced by a pulsed field are examined to analyze the possibility of vesicle fusion. In two different medium conditions, the prolate shape is observed to have selective electroporation at the contact area of vesicles when the exterior conductivity is smaller than the interior one; selective electroporation is more inclined to be found at the poles of the oblate vesicles when the exterior conductivity is larger than the interior one. Furthermore, we find that when the exterior conductivity is lower than the internal conductivity, the pulse can induce a selective electroporation at the contact area between two vesicles regardless of the vesicle shape. Both of these two findings have important practical applications in guiding electrofusion experiments. PMID:27391692

  6. Full flex-grid asynchronous multiplexing demonstrated with Nyquist pulse-shaping.

    Science.gov (United States)

    Schindler, P C; Schmogrow, R; Wolf, S; Baeuerle, B; Nebendahl, B; Koos, C; Freude, W; Leuthold, J

    2014-05-01

    We demonstrate full flex-grid operation with Nyquist frequency division multiplexing. The technique supports high spectral efficiency, asynchronous operation of channels, variable channel loading with different modulation formats and dynamic bandwidth allocation. Data from different sources with different bit and symbol rates are encoded onto electrical Nyquist pulses with different electrical subcarrier frequencies, and then transmitted optically. We give details on the transceiver design with digital signal processing and investigate the implementation penalty as a function of several design parameters such as limited filter length and effective number of bits. Finally, experiments are performed for receivers with direct detection, intradyne and remote heterodyne reception.

  7. Improvement in limit of detection in particle induced X-ray emission by means of rise time and pulse shape discrimination

    Science.gov (United States)

    Papp, Tibor; Lakatos, Tamás; Nejedly, Zdenek; Campbell, John L.

    2002-04-01

    A digital signal processor, based upon high-rate sampling of the preamplifier output, and equipped with rise time and pulse shape discrimination, has been tested in three situations. This processor provided significant improvement of particle induced X-ray emission and X-ray fluorescence detection limits over the state of the art analog processors, depending on the energy and intensity distribution of the X-ray spectra. Additionally it had a superior performance when measurements were performed in an environment of large electronic noise and in large nuclear background environment. It has also improved the reduction of several artifacts in X-ray spectra.

  8. Improvement in limit of detection in particle induced X-ray emission by means of rise time and pulse shape discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Papp, Tibor E-mail: tibpapp@netscape.nettibpapp@yahoo.ca; Lakatos, Tamas; Nejedly, Zdenek; Campbell, John L

    2002-04-01

    A digital signal processor, based upon high-rate sampling of the preamplifier output, and equipped with rise time and pulse shape discrimination, has been tested in three situations. This processor provided significant improvement of particle induced X-ray emission and X-ray fluorescence detection limits over the state of the art analog processors, depending on the energy and intensity distribution of the X-ray spectra. Additionally it had a superior performance when measurements were performed in an environment of large electronic noise and in large nuclear background environment. It has also improved the reduction of several artifacts in X-ray spectra.

  9. Performance verification and system integration tests of the pulse shape processor for the soft x-ray spectrometer onboard ASTRO-H

    Science.gov (United States)

    Takeda, Sawako; Tashiro, Makoto S.; Ishisaki, Yoshitaka; Tsujimoto, Masahiro; Seta, Hiromi; Shimoda, Yuya; Yamaguchi, Sunao; Uehara, Sho; Terada, Yukikatsu; Fujimoto, Ryuichi; Mitsuda, Kazuhisa

    2014-07-01

    The soft X-ray spectrometer (SXS) aboard ASTRO-H is equipped with dedicated digital signal processing units called pulse shape processors (PSPs). The X-ray microcalorimeter system SXS has 36 sensor pixels, which are operated at 50 mK to measure heat input of X-ray photons and realize an energy resolution of 7 eV FWHM in the range 0.3-12.0 keV. Front-end signal processing electronics are used to filter and amplify the electrical pulse output from the sensor and for analog-to-digital conversion. The digitized pulses from the 36 pixels are multiplexed and are sent to the PSP over low-voltage differential signaling lines. Each of two identical PSP units consists of an FPGA board, which assists the hardware logic, and two CPU boards, which assist the onboard software. The FPGA board triggers at every pixel event and stores the triggering information as a pulse waveform in the installed memory. The CPU boards read the event data to evaluate pulse heights by an optimal filtering algorithm. The evaluated X-ray photon data (including the pixel ID, energy, and arrival time information) are transferred to the satellite data recorder along with event quality information. The PSP units have been developed and tested with the engineering model (EM) and the flight model. Utilizing the EM PSP, we successfully verified the entire hardware system and the basic software design of the PSPs, including their communication capability and signal processing performance. In this paper, we show the key metrics of the EM test, such as accuracy and synchronicity of sampling clocks, event grading capability, and resultant energy resolution.

  10. A LINEAR APPROACH TO METRIC CIRCUMFERENCE COMPUTATION FOR DIGITIZED CONVEX SHAPES

    Institute of Scientific and Technical Information of China (English)

    Chen Ken; Zhao Pan; Yang Rener

    2008-01-01

    Metric measurement of digitized shapes is commonly applied in optical measuring systems. In this letter, three shape-related factors defined by the authors are used in the construction of a multiple linear regression model which is utilized to compute the circumference of the convex shapes in millimeter unit. The model is first built upon the relationship hypothesis and then its adequacy is mathematically validated. The results of applying the developed model to the given number of convex shapes in a finite circumferential length range suggest that, in terms of percent error, the model pre- cision is to satisfaction by being within±4%. The test also shows the model's robustness against the shape's orientation anisotropy.

  11. 基于实时数字脉冲处理技术的核谱仪研究%Study of Nuclear Spectrometer Based on Real-time Digital Pulse Process Technique

    Institute of Scientific and Technical Information of China (English)

    周建斌; 胡云川; 洪旭; 陈铁光; 陈宝; 岳爱忠; 何绪新

    2015-01-01

    A digital gamma ray spectrometer based on 80 M Hz ADC was presented .The system consists of NaI(Tl) detector ,front-end circuitry ,80 M Hz ADC and digital pulse process (DPP) unit .The FIR digital filtering ,pulse trapezoidal shaping ,pulse height discrimination and data communication were implemented in DPP .The pulse trapezoidal shaping algorithm was applied to obtain good energy resolution and throughout . In order to reduce the influence of noise introducing from the high-speed ADC ,the FIR digital filter was employed .The digital signal coming from ADC was smoothed by FIR filter firstly ,and then shaped as trapezoidal pulse for further processing . The analog signal was coupled by DC ,and the digital pulse width is 1.6 μs .The results show that the resolution for 137 Cs can reach 6.88% .%本文提出一种基于80 M Hz ADC的数字化γ能谱系统.系统由探测器、前端电路、ADC和数字处理单元组成.数字处理在FPGA中完成 ,主要包括FIR数字滤波、脉冲梯形成形、幅度甄别、数据通讯.为减小高速ADC在采集过程中引入的噪声信号 ,在数字处理单元实现FIR数字滤波 ,对数字脉冲信号先进行滤波处理 ,再进行脉冲梯形成形 ,得到高分辨率的能谱数据.测量系统中模拟信号全部采用直流耦合 ,数字脉冲宽度为1.6 μs ,对137Cs的能量分辨率达6.88% .

  12. Polarization-independent etching of fused silica based on electrons dynamics control by shaped femtosecond pulse trains for microchannel fabrication.

    Science.gov (United States)

    Yan, X; Jiang, L; Li, X; Zhang, K; Xia, B; Liu, P; Qu, L; Lu, Y

    2014-09-01

    We propose an approach to realize polarization-independent etching of fused silica by using temporally shaped femtosecond pulse trains to control the localized transient electrons dynamics. Instead of nanograting formation using traditional unshaped pulses, for the pulse delay of pulse trains larger than 1 ps, coherent field-vector-related coupling is not possible and field orientation is lost. The exponential growth of the periodic structures is interrupted. In this case, disordered and interconnected nanostructures are formed, which is probably the main reason of etching independence on the laser polarization. As an application example, square-wave-shaped and arc-shaped microchannels are fabricated by using pulse trains to demonstrate the advantage of the proposed method in fabricating high-aspect-ratio and three-dimensional microchannels.

  13. Gamma–neutron imaging system utilizing pulse shape discrimination with CLYC

    Energy Technology Data Exchange (ETDEWEB)

    Whitney, Chad M., E-mail: cwhitney@rmdinc.com; Soundara-Pandian, Lakshmi; Johnson, Erik B.; Vogel, Sam; Vinci, Bob; Squillante, Michael; Glodo, Jarek; Christian, James F.

    2015-06-01

    Recently, RMD has investigated the use of CLYC (Cs{sub 2}LiYCl{sub 6}:Ce), a new and emerging scintillation material, in a gamma–neutron coded aperture imaging system based on RMD's commercial RadCam{sup TM} instrument. CLYC offers efficient thermal neutron detection, fast neutron detection capabilities, excellent pulse shape discrimination (PSD), and gamma-ray energy resolution as good as 4% at 662 keV. PSD improves the isolation of higher energy gammas from thermal neutron interactions (>3 MeV electron equivalent peak), compared to conventional pulse height techniques. The scintillation emission time in CLYC provides the basis for PSD; where neutron interactions result in a slower emission rise and decay components while gamma interactions result in a faster emission components. By creating a population plot based on the ratio of the decay tail compared to the total integral amplitude (PSD ratio), discrimination of gammas, thermal neutrons, and fast neutrons is possible. Previously, we characterized the CLYC-based RadCam system for imaging gammas and neutrons using a layered W-Cd coded aperture mask and employing only pulse height discrimination. In this paper, we present the latest results which investigate gamma-neutron imaging capabilities using PSD. An FPGA system is used to acquire the CLYC–PSPMT last dynode signals, determine a PSD ratio for each event, and compare it to a calibrated PSD cutoff. Each event is assigned either a gamma (low) or neutron (high) flag signal which is then correlated with the imaging information for each event. - Highlights: • The latest results are presented for our CLYC RadCam-2 system which investigate gamma–neutron imaging using pulse shape discrimination. • CLYC RadCam-2 system successfully discriminates gammas, thermal neutrons, and fast neutrons by employing a fully integrated, FPGA-based PSD system. • Imaging of our {sup 252}Cf source was possible using both pulse height and pulse shape discrimination with

  14. Pulsed digital holography system recording ultrafast process of the femtosecond order

    Science.gov (United States)

    Wang, Xiaolei; Zhai, Hongchen; Mu, Guoguang

    2006-06-01

    We report, for the first time to our knowledge, a pulsed digital microholographic system with spatial angular multiplexing for recording the ultrafast process of the femtosecond order. The optimized design of the two sets of subpulse-train generators in this system makes it possible to implement a digital holographic recording with spatial angular multiplexing of a frame interval of the femtosecond order, while keeping the incident angle of the object beams unchanged. Three pairs of amplitude and phase images from the same view angle digitally reconstructed by the system demonstrated the ultrafast dynamic process of laser-induced ionization of ambient air at a wavelength of 800 nm, with a time resolution of 50 fs and a frame interval of 300 fs.

  15. Analysis of the scintillation mechanism in a pressurized 4He fast neutron detector using pulse shape fitting

    OpenAIRE

    R.P. Kelley; Murer, D.; Ray, H.; K.A. Jordan

    2015-01-01

    An empirical investigation of the scintillation mechanism in a pressurized 4He gas fast neutron detector was conducted using pulse shape fitting. Scintillation signals from neutron interactions were measured and averaged to produce a single generic neutron pulse shape from both a 252Cf spontaneous fission source and a (d,d) neutron generator. An expression for light output over time was then developed by treating the decay of helium excited states in the same manner as the decay of radioactiv...

  16. Pulsed-mode operation and performance of a ferromagnetic shape memory alloy actuator

    Science.gov (United States)

    Asua, E.; García-Arribas, A.; Etxebarria, V.; Feuchtwanger, J.

    2014-02-01

    The actuation capabilities and positioning performance of a single crystal ferromagnetic shape memory alloy (FSMA) operated in pulsed mode are evaluated in a prototype device. It consists of two orthogonal coil pairs that produce the magnetic fields necessary for the non-contact deformation of the material. The position of the top of the crystal after actuation is measured by a capacitive sensor. A specifically designed power module drives the discharge of a set of capacitors through the coils, producing fast current pulses of large amplitudes (about 250 A), the coil pairs are driven independently to control the direction of actuation. Open-loop experiments demonstrate that successive pulses of increasing magnitude successfully produced the desired expansion and contraction of the crystal, depending on the pair of coils that is activated. The deformation achieved is maintained after the pulses, highlighting the advantageous set-and-forget operation of the device. Closed-loop experiments are performed using a double proportional-integral-derivative controller, designed to take advantage of the energy-saving quality of the set-and-forget operation. Despite the nonlinear response and hysteric response of FSMA materials, a reference position can be reached and maintained with a maximum error of 0.5 μm.

  17. Noise-shaping all-digital phase-locked loops modeling, simulation, analysis and design

    CERN Document Server

    Brandonisio, Francesco

    2014-01-01

    This book presents a novel approach to the analysis and design of all-digital phase-locked loops (ADPLLs), technology widely used in wireless communication devices. The authors provide an overview of ADPLL architectures, time-to-digital converters (TDCs) and noise shaping. Realistic examples illustrate how to analyze and simulate phase noise in the presence of sigma-delta modulation and time-to-digital conversion. Readers will gain a deep understanding of ADPLLs and the central role played by noise-shaping. A range of ADPLL and TDC architectures are presented in unified manner. Analytical and simulation tools are discussed in detail. Matlab code is included that can be reused to design, simulate and analyze the ADPLL architectures that are presented in the book.   • Discusses in detail a wide range of all-digital phase-locked loops architectures; • Presents a unified framework in which to model time-to-digital converters for ADPLLs; • Explains a procedure to predict and simulate phase noise in oscil...

  18. Pulse Shaping for High Capacity Impulse Radio Ultra-Wideband Wireless Links Under the Russian Spectral Emission Mask

    DEFF Research Database (Denmark)

    Grakhova, Elizaveta P.; Rommel, Simon; Jurado-Navas, Antonio

    2016-01-01

    Two pulse shapes for IR-UWB transmission under the Russian spectral emission mask are proposed and their potential experimentally demonstrated. Pulses based on the hyperbolic secant square function and the frequency B-spline wavelet are shown to enable transmission of 1.25 Gbit/s signals, reachin...

  19. Shaping speckles: spatio-temporal focussing of an ultrafast pulse through a multiply scattering medium

    CERN Document Server

    McCabe, David J; Austin, Dane R; Bondareff, Pierre; Walmsley, Ian A; Gigan, Sylvain; Chatel, Béatrice

    2011-01-01

    The multiple scattering of coherent light is a problem of both fundamental and applied importance. In optics, phase conjugation allows spatial focussing and imaging through a multiply scattering medium; however, temporal control is nonetheless elusive, and multiple scattering remains a challenge for femtosecond science. Here, we report on the spatially and temporally resolved measurement of a speckle field produced by the propagation of an ultrafast optical pulse through a thick strongly scattering medium. Using spectral pulse shaping, we demonstrate the spatially localized temporal recompression of the output speckle to the Fourier-limit duration, offering an optical analogue to time-reversal experiments in the acoustic regime. This approach shows that a multiply scattering medium can be put to profit for light manipulation at the femtosecond scale, and has a diverse range of potential applications that includes quantum control, biological imaging and photonics.

  20. Improving the power efficiency of SOA-based UWB over fiber systems via pulse shape randomization

    Science.gov (United States)

    Taki, H.; Azou, S.; Hamie, A.; Al Housseini, A.; Alaeddine, A.; Sharaiha, A.

    2016-09-01

    A simple pulse shape randomization scheme is considered in this paper for improving the performance of ultra wide band (UWB) communication systems using On Off Keying (OOK) or pulse position modulation (PPM) formats. The advantage of the proposed scheme, which can be either employed for impulse radio (IR) or for carrier-based systems, is first theoretically studied based on closed-form derivations of power spectral densities. Then, we investigate an application to an IR-UWB over optical fiber system, by utilizing the 4th and 5th orders of Gaussian derivatives. Our approach proves to be effective for 1 Gbps-PPM and 2 Gbps-OOK transmissions, with an advantage in terms of power efficiency for short distances. We also examine the performance for a system employing an in-line Semiconductor Optical Amplifier (SOA) with the view to achieve a reach extension, while limiting the cost and system complexity.

  1. Application of pulse shape discrimination in Si detector for fission fragment angular distribution measurements

    Indian Academy of Sciences (India)

    B K Nayak; E T Mirgule; R K Choudhury

    2005-12-01

    Pulse shape discrimination (PSD) with totally depleted transmission type Si surface barrier detector in reverse mount has been investigated to identify fission fragments in the presence of elastic background in heavy ion-induced fission reactions by both numerical simulation and experimental studies. The PSD method is compared with the other conventional methods adopted to identify fission fragments with solid-state detectors such as - telescope and single thin detector and the data for the 10B + 232Th fission reaction are presented. Results demonstrate the usefulness of a single transmission-type surface barrier detector for the identification of fission fragments and projectiles like heavy ions.

  2. Development of GAGG depth-of-interaction (DOI) block detectors based on pulse shape analysis

    Science.gov (United States)

    Yamamoto, Seiichi; Kobayashi, Takahiro; Yeol Yeom, Jung; Morishita, Yuki; Sato, Hiroki; Endo, Takanori; Usuki, Yoshiyuki; Kamada, Kei; Yoshikawa, Akira

    2014-12-01

    A depth-of-interaction (DOI) detector is required for developing a high resolution and high sensitivity PET system. Ce-doped Gd3Al2Ga3O12 (GAGG fast: GAGG-F) is a promising scintillator for PET applications with high light output, no natural radioisotope and suitable light emission wavelength for semiconductor based photodetectors. However, no DOI detector based on pulse shape analysis with GAGG-F has been developed to date, due to the lack of appropriate scintillators of pairing. Recently a new variation of this scintillator with different Al/Ga ratios-Ce-doped Gd3Al2.6Ga2.4O12 (GAGG slow: GAGG-S), which has slower decay time was developed. The combination of GAGG-F and GAGG-S may allow us to realize high resolution DOI detectors based on pulse shape analysis. We developed and tested two GAGG phoswich DOI block detectors comprised of pixelated GAGG-F and GAGG-S scintillation crystals. One phoswich block detector comprised of 2×2×5 mm pixel that were assembled into a 5×5 matrix. The DOI block was optically coupled to a silicon photomultiplier (Si-PM) array (Hamamatsu MPPC S11064-050P) with a 2-mm thick light guide. The other phoswich block detector comprised of 0.5×0.5×5 mm (GAGG-F) and 0.5×0.5×6 mm3 (GAGG-S) pixels that were assembled into a 20×20 matrix. The DOI block was also optically coupled to the same Si-PM array with a 2-mm thick light guide. In the block detector of 2-mm crystal pixels (5×5 matrix), the 2-dimensional histogram revealed excellent separation with an average energy resolution of 14.1% for 662-keV gamma photons. The pulse shape spectrum displayed good separation with a peak-to-valley ratio of 8.7. In the block detector that used 0.5-mm crystal pixels (20×20 matrix), the 2-dimensional histogram also showed good separation with energy resolution of 27.5% for the 662-keV gamma photons. The pulse shape spectrum displayed good separation with a peak-to-valley ratio of 6.5. These results indicate that phoswich DOI detectors with the two

  3. Comparative analysis of pulse shape discrimination methods in a {sup 6}Li loaded plastic scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Balmer, Matthew J.I., E-mail: m.balmer@lancaster.ac.uk [Department of Engineering, Lancaster University, LA1 4YR (United Kingdom); Gamage, Kelum A.A. [Department of Engineering, Lancaster University, LA1 4YR (United Kingdom); Taylor, Graeme C. [Neutron Metrology Group, National Physical Laboratory, Teddington, TW11 0LW (United Kingdom)

    2015-07-11

    Three algorithms for discriminating between fast neutrons, thermal neutrons and gamma rays in a {sup 6}Li loaded plastic scintillator have been compared. Following a literature review of existing pulse shape discrimination techniques, the performance of the charge comparison method, triangular filtering and frequency gradient analysis were investigated in this work. The scintillator was exposed to three different mixed gamma/neutron radiation fields. The figure of merit of neutron/gamma separation was investigated over a broad energy range, as well as for the neutron capture energy region. After optimisation, all three methods were found to perform similarly in terms of neutron/gamma separation.

  4. Development of GAGG depth-of-interaction (DOI) block detectors based on pulse shape analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Seiichi, E-mail: s-yama@met.nagoya-u.ac.jp [Nagoya University Graduate School of Medicine, Nagoya (Japan); Kobayashi, Takahiro [Nagoya University Graduate School of Medicine, Nagoya (Japan); Department of Radiology, Daiyukai General Hospital, Ichinomiya (Japan); Yeol Yeom, Jung [Kumoh National institute of Technology, Gumi (Korea, Republic of); Morishita, Yuki [Nagoya University Graduate School of Medicine, Nagoya (Japan); Sato, Hiroki; Endo, Takanori; Usuki, Yoshiyuki [Furukawa Corporation, Ichihara (Japan); Kamada, Kei [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai (Japan); Yoshikawa, Akira [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai (Japan); Institute for Materials Research (IMR), Tohoku University, Tohoku (Japan)

    2014-12-11

    A depth-of-interaction (DOI) detector is required for developing a high resolution and high sensitivity PET system. Ce-doped Gd{sub 3}Al{sub 2}Ga{sub 3}O{sub 12} (GAGG fast: GAGG-F) is a promising scintillator for PET applications with high light output, no natural radioisotope and suitable light emission wavelength for semiconductor based photodetectors. However, no DOI detector based on pulse shape analysis with GAGG-F has been developed to date, due to the lack of appropriate scintillators of pairing. Recently a new variation of this scintillator with different Al/Ga ratios—Ce-doped Gd{sub 3}Al{sub 2.6}Ga{sub 2.4}O{sub 12} (GAGG slow: GAGG-S), which has slower decay time was developed. The combination of GAGG-F and GAGG-S may allow us to realize high resolution DOI detectors based on pulse shape analysis. We developed and tested two GAGG phoswich DOI block detectors comprised of pixelated GAGG-F and GAGG-S scintillation crystals. One phoswich block detector comprised of 2×2×5 mm pixel that were assembled into a 5×5 matrix. The DOI block was optically coupled to a silicon photomultiplier (Si-PM) array (Hamamatsu MPPC S11064-050P) with a 2-mm thick light guide. The other phoswich block detector comprised of 0.5×0.5×5 mm (GAGG-F) and 0.5×0.5×6 mm{sup 3} (GAGG-S) pixels that were assembled into a 20×20 matrix. The DOI block was also optically coupled to the same Si-PM array with a 2-mm thick light guide. In the block detector of 2-mm crystal pixels (5×5 matrix), the 2-dimensional histogram revealed excellent separation with an average energy resolution of 14.1% for 662-keV gamma photons. The pulse shape spectrum displayed good separation with a peak-to-valley ratio of 8.7. In the block detector that used 0.5-mm crystal pixels (20×20 matrix), the 2-dimensional histogram also showed good separation with energy resolution of 27.5% for the 662-keV gamma photons. The pulse shape spectrum displayed good separation with a peak-to-valley ratio of 6.5. These

  5. In situ imaging of hole shape evolution in ultrashort pulse laser drilling.

    Science.gov (United States)

    Döring, Sven; Richter, Sören; Nolte, Stefan; Tünnermann, Andreas

    2010-09-13

    For the first time, in situ the hole shape evolution during ultrashort pulse laser drilling in semiconductor material is imaged. The trans-illumination of the sample at a wavelength of 1.06 µm is projected onto a standard CCD camera during the ablation, providing an image of the contour of the ablated structure perpendicular to the irradiation for drilling. This demonstrated technique enables a direct, high resolution investigation of the temporal evolution of the drilling process in the depth of the material without complex sample preparation or post processing.

  6. An online detection system for aggregate sizes and shapes based on digital image processing

    Science.gov (United States)

    Yang, Jianhong; Chen, Sijia

    2016-07-01

    Traditional aggregate size measuring methods are time-consuming, taxing, and do not deliver online measurements. A new online detection system for determining aggregate size and shape based on a digital camera with a charge-coupled device, and subsequent digital image processing, have been developed to overcome these problems. The system captures images of aggregates while falling and flat lying. Using these data, the particle size and shape distribution can be obtained in real time. Here, we calibrate this method using standard globules. Our experiments show that the maximum particle size distribution error was only 3 wt%, while the maximum particle shape distribution error was only 2 wt% for data derived from falling aggregates, having good dispersion. In contrast, the data for flat-lying aggregates had a maximum particle size distribution error of 12 wt%, and a maximum particle shape distribution error of 10 wt%; their accuracy was clearly lower than for falling aggregates. However, they performed well for single-graded aggregates, and did not require a dispersion device. Our system is low-cost and easy to install. It can successfully achieve online detection of aggregate size and shape with good reliability, and it has great potential for aggregate quality assurance.

  7. Note: High resolution ultra fast high-power pulse generator for inductive load using digital signal processor.

    Science.gov (United States)

    Flaxer, Eli

    2014-08-01

    We present a new design of a compact, ultra fast, high resolution and high-powered, pulse generator for inductive load, using power MOSFET, dedicated gate driver and a digital signal controller. This design is an improved circuit of our old version controller. We demonstrate the performance of this pulse generator as a driver for a new generation of high-pressure supersonic pulsed valves.

  8. Advanced pulse-shape analysis and implementation of gamma-ray tracking in a position-sensitive coaxial HPGe detector

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, Austin Lee [Univ. of California, Berkeley, CA (United States)

    2002-11-12

    A new concept in g-radiation detection utilizing highly segmented positionsensitive germanium detectors is currently being developed. Through pulse-shape analysis these detectors will provide the three-dimensional position and energy of individual γ-ray interactions and allow the full-energy and direction vectors of the incident radiation to be reconstructed in a process termed tracking. Here, a prototype segmented detector has been utilized in the assessment of theoretically modeled pulse shapes to gain insight into the factors that effect their agreement with those experimentally measured. It was found that simple modeling of the charge-collection process would provide fair agreement between calculated and experimental pulse shapes. However, in some cases significant deviations between the two were present. This was a result of insufficient modeling of all the processes involved in pulse-shape formation. Factors contributing to this include the three-dimensional spatial distribution of the charge carriers, the path of the primary electron, and fluctuations in the electric fields near electrode surfaces and due to variations in impurity concentrations. Additionally, the sensitivity of pulse shapes to changes in the interaction location has been studied. The results indicate that single interactions with energy deposition of 662 keV can potentially be localized to better than the desired position resolution of 2 mm. However, when the study was extended to two interactions totaling 662 keV a different conclusion was reached. It was shown that the pulse shapes resulting from two interactions were ambiguous with that of pulse shapes from single interactions over dimensions greater than 2 mm in the larger detector segments. The size of these segments in future detectors must be reduced in order to increase their sensitivity. Ultimately, a signal decomposition algorithm was developed and implemented to extract the position and energy of γ-ray interactions, occurring

  9. Probing spatial properties of electronic excitation in water after interaction with temporally shaped femtosecond laser pulses: Experiments and simulations

    Science.gov (United States)

    Winkler, Thomas; Sarpe, Cristian; Jelzow, Nikolai; Lasse H., Lillevang; Götte, Nadine; Zielinski, Bastian; Balling, Peter; Senftleben, Arne; Baumert, Thomas

    2016-06-01

    In this work, laser excitation of water under ambient conditions is investigated by radially resolved common-path spectral interferometry. Water, as a sample system for dielectric materials, is excited by ultrashort bandwidth-limited and temporally asymmetric shaped femtosecond laser pulses, where the latter start with an intense main pulse followed by a decaying pulse sequence, i.e. a temporal Airy pulse. Spectral interference in an imaging geometry allows measurements of the transient optical properties integrated along the propagation through the sample but radially resolved with respect to the transverse beam profile. Since the optical properties reflect the dynamics of the free-electron plasma, such measurements reveal the spatial characteristics of the laser excitation. We conclude that temporally asymmetric shaped laser pulses are a promising tool for high-precision laser material processing, as they reduce the transverse area of excitation, but increase the excitation inside the material along the beam propagation.

  10. Shape tailoring of hexagonally ordered triangular gold nanoparticles with nanosecond-pulsed laser light

    Energy Technology Data Exchange (ETDEWEB)

    Morarescu, Rodica; Sanchez, David Blazquez; Borg, Nils [Institut fuer Physik and Center for Interdisciplinary Nanostructure Science and Technology - CINSaT, Universitaet Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel (Germany); Vartanyan, Tigran A. [Center for Informational Optical Technologies St. Petersburg State University of Informational Technologies, Mechanics and Optics, Kronverkskiy pr. 49, St. Petersburg 197101 (Russian Federation); Traeger, Frank [Institut fuer Physik and Center for Interdisciplinary Nanostructure Science and Technology - CINSaT, Universitaet Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel (Germany); Hubenthal, Frank, E-mail: hubentha@physik.uni-kassel.de [Institut fuer Physik and Center for Interdisciplinary Nanostructure Science and Technology - CINSaT, Universitaet Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel (Germany)

    2009-09-30

    In this contribution recent results on selective and precise tailoring of triangular gold nanoparticles (NPs) using ns-pulsed laser light are presented. The NPs were prepared by nanosphere lithography and subsequently tailored with ns-pulsed laser light using different fluences and wavelengths. The method is based on the size and shape dependent localized surface plasmon polariton resonance (SPR) of the NPs. We will demonstrate that the gap size between triangular NPs can be tuned from approximately 102{+-}14 nm to 122{+-}11 nm, due to a shape change of the NP from triangular to oblate. These morphological changes are accompanied by a significant shift of the surface plasmon resonance from {lambda}{sub SPR}=730 nm to {lambda}{sub SPR}=680 nm. Most importantly if the laser wavelength is chosen such that the dipolar SPR is excited, the hexagonal order of the NPs remains intact after irradiation, in contrast to excitation via the quadrupole SPR or within the interband transition. A tuneable gap size and the conservation of the hexagonal order of the NP array is the precondition for applications, where the NPs should serve as anchor points, e.g. for functional molecular nanowires, which can be used to utilize molecular devices.

  11. Novel applications of photonic signal processing: Temporal cloaking and biphoton pulse shaping

    Science.gov (United States)

    Lukens, Joseph M.

    We experimentally demonstrate two innovative applications of photonic technologies previously solidified in the field of classical optical communications. In the first application, we exploit electro-optic modulator technology to develop a novel "time cloak,'' a device which hides events in time by manipulating the flow of a probing light beam. Our temporal cloak is capable of masking high-speed optical data from a receiver, greatly improving the feasibility of time cloaking and bringing such exotic concepts to the verge of practical application. In the second specialization, high-resolution Fourier-transform pulse shaping---perfected for multi-wavelength telecom networks---is applied to shape the correlations of entangled photon pairs, states which have received considerable attention in nonlocal tests of quantum theory and in quantum key distribution. Using nonlinear waveguides fabricated out of periodically poled lithium niobate, we are able to demonstrate ultrafast coincidence detection with record-high efficiency, which coupled with our pulse shaper allows us to realize for the first time several capabilities in biphoton control, including high-order dispersion cancellation, orthogonal spectral coding, correlation train generation, and tunable delay control. Each of these experiments represents an important advance in quantum state manipulation, with the potential to impact developments in quantum information. And more generally, our work introducing telecommunication technology into both temporal cloaking and biphoton control highlights the potential of such tools in more nascent outgrowths of classical and quantum optics.

  12. Toward direct light-to-digital conversion using a pulse-driven hybrid MOS-PN photodetector.

    Science.gov (United States)

    Sallin, Denis; Koukab, Adil; Kayal, Maher

    2015-02-15

    In this Letter, a direct light-to-digital converter based on an MOS-PN photodetector driven by pulsed voltage is presented. The objective is to avoid any analog-to-digital or time-to-digital conversion and, thereby, to pave the way for a new generation of fully digital imaging sensors with reduced complexity, area, and power consumption. Moreover, the pulsed voltage operation allows for a significant reduction of the dark level. The concept is validated by a theoretical study and TCAD simulations. A first prototype fabricated in 0.18 μm CMOS technology is presented. The experimental results under various light conditions show that the pulsed voltage improves the light sensitivity by several orders of magnitude.

  13. Pulse shape discrimination characteristics of stilbene crystal, pure and 6Li loaded plastic scintillators for a high resolution coded-aperture neutron imager

    Science.gov (United States)

    Cieślak, M. J.; Gamage, K. A. A.; Glover, R.

    2017-07-01

    Pulse shape discrimination performances of single stilbene crystal, pure plastic and 6Li loaded plastic scintillators have been compared. Three pulse shape discrimination algorithms have been tested for each scintillator sample, assessing their quality of neutron/gamma separation. Additionally, the digital implementation feasibility of each algorithm in a real-time embedded system was evaluated. Considering the pixelated architecture of the coded-aperture imaging system, a reliable method of simultaneous multi-channel neutron/gamma discrimination was sought, accounting for the short data analysis window available for each individual channel. In this study, each scintillator sample was irradiated with a 252Cf neutron source and a bespoke digitiser system was used to collect the data allowing detailed offline examination of the sampled pulses. The figure-of-merit was utilised to compare the discrimination quality of the collected events with respect to various discrimination algorithms. Single stilbene crystal presents superior neutron/gamma separation performance when compared to the plastic scintillator samples.

  14. Energy-optimal electrical-stimulation pulses shaped by the Least-Action Principle.

    Directory of Open Access Journals (Sweden)

    Nedialko I Krouchev

    Full Text Available Electrical stimulation (ES devices interact with excitable neural tissue toward eliciting action potentials (AP's by specific current patterns. Low-energy ES prevents tissue damage and loss of specificity. Hence to identify optimal stimulation-current waveforms is a relevant problem, whose solution may have significant impact on the related medical (e.g. minimized side-effects and engineering (e.g. maximized battery-life efficiency. This has typically been addressed by simulation (of a given excitable-tissue model and iterative numerical optimization with hard discontinuous constraints--e.g. AP's are all-or-none phenomena. Such approach is computationally expensive, while the solution is uncertain--e.g. may converge to local-only energy-minima and be model-specific. We exploit the Least-Action Principle (LAP. First, we derive in closed form the general template of the membrane-potential's temporal trajectory, which minimizes the ES energy integral over time and over any space-clamp ionic current model. From the given model we then obtain the specific energy-efficient current waveform, which is demonstrated to be globally optimal. The solution is model-independent by construction. We illustrate the approach by a broad set of example situations with some of the most popular ionic current models from the literature. The proposed approach may result in the significant improvement of solution efficiency: cumbersome and uncertain iteration is replaced by a single quadrature of a system of ordinary differential equations. The approach is further validated by enabling a general comparison to the conventional simulation and optimization results from the literature, including one of our own, based on finite-horizon optimal control. Applying the LAP also resulted in a number of general ES optimality principles. One such succinct observation is that ES with long pulse durations is much more sensitive to the pulse's shape whereas a rectangular pulse is most

  15. On-line digital holographic measurement of size and shape of microparticles for crystallization processes

    Science.gov (United States)

    Khanam, Taslima; Darakis, Emmanouil; Rajendran, Arvind; Kariwala, Vinay; Asundi, Anand K.; Naughton, Thomas J.

    2008-09-01

    Crystallization is a widely used chemical process that finds applications in pharmaceutical industries. In an industrial crystallization process, it is not only important to produce pure crystals but also to control the shape and size of the crystals, as they affect the efficiency of downstream processes and the dissolution property of the drug. The effectiveness of control algorithms depend on the availability of on-line, real-time information about these critical properties. In this paper, we investigate the use of lens-less in-line digital holographic microscopy for size and shape measurements for crystallization processes. For this purpose, we use non-crystalline spherical microparticles and carbon fibers with known sizes present in a liquid suspension as test systems. We propose an algorithm to extract size and shape information for a population of microparticles from the experimentally recorded digital holograms. The measurements obtained from the proposed method show good agreement with the corresponding known size and shape of the particles.

  16. Fluorescence microscopy beyond the ballistic regime by ultrasound pulse guided digital phase conjugation

    CERN Document Server

    Cui, Meng; Fiolka, Reto

    2012-01-01

    Fluorescence microscopy has revolutionized biomedical research over the past three decades. Its high molecular specificity and unrivaled single molecule level sensitivity have enabled breakthroughs in a variety of research fields. For in vivo applications, its major limitation is the superficial imaging depth as random scattering in biological tissues causes exponential attenuation of the ballistic component of a light wave. Here we present fluorescence microscopy beyond the ballistic regime by combining single cycle pulsed ultrasound modulation and digital optical phase conjugation. We demonstrate near isotropic 3D localized sound-light interaction with an imaging depth as high as thirteen scattering path lengths. With the exceptionally high optical gain provided by the digital optical phase conjugation system, we can deliver sufficient optical power to a focus inside highly scattering media for not only fluorescence microscopy but also a variety of linear and nonlinear spectroscopy measurements. This techno...

  17. Natural discharge after pulse and cooperative electrodes to enhance droplet velocity in digital microfluidics

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Tianlan; Dong, Cheng; Gao, Jie; Jia, Yanwei; Mak, Pui-In, E-mail: pimak@umac.mo; Vai, Mang-I; Martins, Rui P. [State Key Laboratory of Analog and Mixed-Signal VLSI and FST-ECE, University of Macau, Macao (China)

    2014-04-15

    Digital Microfluidics (DMF) is a promising technology for biological/chemical micro-reactions due to its distinct droplet manageability via electronic automation, but the limited velocity of droplet transportation has hindered DMF from utilization in high throughput applications. In this paper, by adaptively fitting the actuation voltages to the dynamic motions of droplet movement under real-time feedback monitoring, two control-engaged electrode-driving techniques: Natural Discharge after Pulse (NDAP) and Cooperative Electrodes (CE) are proposed. They together lead to, for the first time, enhanced droplet velocity with lower root mean square voltage value.

  18. Digital pulse-timing technique for the neutron detector array NEDA

    Energy Technology Data Exchange (ETDEWEB)

    Modamio, V., E-mail: victor.modamio@lnl.infn.it [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Valiente-Dobón, J.J. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Jaworski, G. [Faculty of Physics, Warsaw University of Technology, 00-662 Warszawa (Poland); Heavy Ion Laboratory, University of Warsaw, 02-093 Warszawa (Poland); Hüyük, T. [Instituto de Física Corpuscular, CSIC-Universitat de València, E-46980 Valencia (Spain); Triossi, A. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Egea, J. [Instituto de Física Corpuscular, CSIC-Universitat de València, E-46980 Valencia (Spain); Department of Electronic Engineering, Universitat de València, E-46100 Burjassot (Spain); Di Nitto, A. [Johannes Gutenberg-Universität Mainz, D-55099 Mainz (Germany); Söderström, P.-A. [RIKEN Nishina Center, 2-1 Hirosawa, Wako-shi, 351-0198 Saitama (Japan); Agramunt Ros, J. [Instituto de Física Corpuscular, CSIC-Universitat de València, E-46980 Valencia (Spain); Angelis, G. de [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); France, G. de [GANIL, CEA/DSAM and CNRS/IN2P3, F-14076 Caen (France); Erduran, M.N. [Faculty of Engineering and Natural Sciences, Istanbul Sabahattin Zaim University, 34303 Istanbul (Turkey); and others

    2015-03-01

    A new digital pulse-timing algorithm, to be used with the future neutron detector array NEDA, has been developed and tested. The time resolution of four 5 in. diameter photomultiplier tubes (XP4512, R4144, R11833-100, and ET9390-kb), coupled to a cylindrical 5 in. by 5 in. BC501A liquid scintillator detector was measured by employing digital sampling electronics and a constant fraction discriminator (CFD) algorithm. The zero crossing of the CFD algorithm was obtained with a cubic spline interpolation, which was continuous up to the second derivative. The performance of the algorithm was studied at sampling rates of 500 MS/s and 200 MS/s. The time resolution obtained with the digital electronics was compared to the values acquired with a standard analog CFD. The result of this comparison shows that the time resolution from the analog and the digital measurements at 500 MS/s and at 200 MS/s are within 15% for all the tested photomultiplier tubes.

  19. Transformation of irregular shaped silver nanostructures into nanoparticles by under water pulsed laser melting.

    Science.gov (United States)

    Yadavali, S; Sandireddy, V P; Kalyanaraman, R

    2016-05-13

    The ability to easily manufacture nanostructures with a desirable attribute, such as well-defined size and shape, especially from any given initial shapes or sizes of the material, will be helpful towards accelerating the use of nanomaterials in various applications. In this work we report the transformation of discontinuous irregular nanostructures (DIN) of silver metal by rapid heating under a bulk fluid layer. Ag films were changed into DIN by dewetting in air and subsequently heated by nanosecond laser pulses under water. Our findings show that the DIN first ripens into elongated structures and then breaks up into nanoparticles. From the dependence of this behavior on laser fluence we found that under water irradiation reduced the rate of ripening and also decreased the characteristic break-up length scale of the elongated structures. This latter result was qualitatively interpreted as arising from a Rayleigh-Plateau instability modified to yield significantly smaller length scales than the classical process due to pressure gradients arising from the rapid evaporation of water during laser melting. These results demonstrate that it is possible to fabricate a dense collection of monomodally sized Ag nanoparticles with significantly enhanced plasmonic quality starting from the irregular shaped materials. This can be beneficial towards transforming discontinuous Ag films into nanostructures with useful plasmonic properties, that are relevant for biosensing applications.

  20. Noise-shaping gradient descent-based online adaptation algorithms for digital calibration of analog circuits.

    Science.gov (United States)

    Chakrabartty, Shantanu; Shaga, Ravi K; Aono, Kenji

    2013-04-01

    Analog circuits that are calibrated using digital-to-analog converters (DACs) use a digital signal processor-based algorithm for real-time adaptation and programming of system parameters. In this paper, we first show that this conventional framework for adaptation yields suboptimal calibration properties because of artifacts introduced by quantization noise. We then propose a novel online stochastic optimization algorithm called noise-shaping or ΣΔ gradient descent, which can shape the quantization noise out of the frequency regions spanning the parameter adaptation trajectories. As a result, the proposed algorithms demonstrate superior parameter search properties compared to floating-point gradient methods and better convergence properties than conventional quantized gradient-methods. In the second part of this paper, we apply the ΣΔ gradient descent algorithm to two examples of real-time digital calibration: 1) balancing and tracking of bias currents, and 2) frequency calibration of a band-pass Gm-C biquad filter biased in weak inversion. For each of these examples, the circuits have been prototyped in a 0.5-μm complementary metal-oxide-semiconductor process, and we demonstrate that the proposed algorithm is able to find the optimal solution even in the presence of spurious local minima, which are introduced by the nonlinear and non-monotonic response of calibration DACs.

  1. Graphical processing unit implementation of an integrated shape-based active contour: Application to digital pathology

    Directory of Open Access Journals (Sweden)

    Sahirzeeshan Ali

    2011-01-01

    Full Text Available Commodity graphics hardware has become a cost-effective parallel platform to solve many general computational problems. In medical imaging and more so in digital pathology, segmentation of multiple structures on high-resolution images, is often a complex and computationally expensive task. Shape-based level set segmentation has recently emerged as a natural solution to segmenting overlapping and occluded objects. However the flexibility of the level set method has traditionally resulted in long computation times and therefore might have limited clinical utility. The processing times even for moderately sized images could run into several hours of computation time. Hence there is a clear need to accelerate these segmentations schemes. In this paper, we present a parallel implementation of a computationally heavy segmentation scheme on a graphical processing unit (GPU. The segmentation scheme incorporates level sets with shape priors to segment multiple overlapping nuclei from very large digital pathology images. We report a speedup of 19× compared to multithreaded C and MATLAB-based implementations of the same scheme, albeit with slight reduction in accuracy. Our GPU-based segmentation scheme was rigorously and quantitatively evaluated for the problem of nuclei segmentation and overlap resolution on digitized histopathology images corresponding to breast and prostate biopsy tissue specimens.

  2. A Model for the Secondary Scintillation Pulse Shape from a Gas Proportional Scintillation Counter

    CERN Document Server

    Kazkaz, Kareem

    2015-01-01

    Proportional scintillation counters (PSCs), both single- and dual-phase, can measure the scintillation (S1) and ionization (S2) channels from particle interactions within the detector volume. The signal obtained from these detectors depends first on the physics of the medium (the initial scintillation and ionization), and second how the physics of the detector manipulates the resulting photons and liberated electrons. In this paper we develop a model of the detector physics that incorporates event topology, detector geometry, electric field configuration, purity, optical properties of components, and wavelength shifters. We present an analytic form of the model, which allows for general study of detector design and operation, and a Monte Carlo model which enables a more detailed exploration of S2 events. This model may be used to study systematic effects in currents detectors such as energy and position reconstruction, pulse shape discrimination, event topology, dead time calculations, purity, and electric fi...

  3. Statistical and Machine-Learning Classifier Framework to Improve Pulse Shape Discrimination System Design

    Energy Technology Data Exchange (ETDEWEB)

    Wurtz, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kaplan, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-28

    Pulse shape discrimination (PSD) is a variety of statistical classifier. Fully-­realized statistical classifiers rely on a comprehensive set of tools for designing, building, and implementing. PSD advances rely on improvements to the implemented algorithm. PSD advances can be improved by using conventional statistical classifier or machine learning methods. This paper provides the reader with a glossary of classifier-­building elements and their functions in a fully-­designed and operational classifier framework that can be used to discover opportunities for improving PSD classifier projects. This paper recommends reporting the PSD classifier’s receiver operating characteristic (ROC) curve and its behavior at a gamma rejection rate (GRR) relevant for realistic applications.

  4. Limitations of the pulse-shape technique for particle discrimination in planar Si detectors

    Energy Technology Data Exchange (ETDEWEB)

    Pausch, G.; Seidel, W. [Forschungszentrum Rossendorf e.V. (FZR), Dresden (Germany). Inst. fuer Kern- und Hadronenphysik; Moszynski, M.; Wolski, D. [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland). Dept. of Nuclear Electronics; Bohne, W. [Hahn-Meitner-Institut Berlin GmbH (Germany). Bereich Festkoerperphysik; Cederkaell, J.; Klamra, W. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Physics; Grawe, H.; Schubart, R. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Lampert, M.O.; Rohr, P. [Eurisys Mesures, 67 - Tanneries (France)

    1996-11-01

    Limitations of the pulse-shape discrimination (PSD) technique - a promising method to identify the charged particles stopped in planar Si-detectors - have been investigated. The particle resolution turned out to be basically determined by resistivity fluctuations in the bulk silicon which cause the charge-collection time to depend on the point of impact. Detector maps showing these fluctuations have been measured and are discussed. Furthermore we present a simple method to test the performance of detectors with respect to PSD. Another limitation of the PSD technique is the finite energy threshold for particle identification. This threshold is caused by an unexpected decrease of the total charge-collection time for ions with a short range, in spite of the fact that the particle tracks are located in a region of very low electric field. (orig.)

  5. Shaped-pulse optimization of coherent emission of high-harmonic soft X-rays

    Science.gov (United States)

    Bartels; Backus; Zeek; Misoguti; Vdovin; Christov; Murnane; Kapteyn

    2000-07-13

    When an intense laser pulse is focused into a gas, the light-atom interaction that occurs as atoms are ionized results in an extremely nonlinear optical process--the generation of high harmonics of the driving laser frequency. Harmonics that extend up to orders of about 300 have been reported, some corresponding to photon energies in excess of 500 eV. Because this technique is simple to implement and generates coherent, laser-like, soft X-ray beams, it is currently being developed for applications in science and technology; these include probing the dynamics in chemical and materials systems and imaging. Here we report that by carefully tailoring the shapes of intense light pulses, we can control the interaction of light with an atom during ionization, improving the efficiency of X-ray generation by an order of magnitude. We demonstrate that it is possible to tune the spectral characteristics of the emitted radiation, and to steer the interaction between different orders of nonlinear processes.

  6. Limitations in timing precision due to single-pulse shape variability in millisecond pulsars

    CERN Document Server

    Shannon, R M; Dai, S; Bailes, M; Hobbs, G; Manchester, R N; van Straten, W; Raithel, C A; Ravi, V; Toomey, L; Bhat, N D R; Burke-Spolaor, S; Coles, W A; Keith, M J; Kerr, M; Levin, Y; Sarkissian, J M; Wang, J -B; Wen, L; Zhu, X -J

    2014-01-01

    High-sensitivity radio-frequency observations of millisecond pulsars usually show stochastic, broadband, pulse-shape variations intrinsic to the pulsar emission process. These variations induce jitter noise in pulsar timing observations; understanding the properties of this noise is of particular importance for the effort to detect gravitational waves with pulsar timing arrays. We assess the short-term profile and timing stability of 22 millisecond pulsars that are part of the Parkes Pulsar Timing Array sample by examining intra-observation arrival time variability and single-pulse phenomenology. In 7 of the 22 pulsars, in the band centred at approximately 1400MHz, we find that the brightest observations are limited by intrinsic jitter. We find consistent results, either detections or upper limits, for jitter noise in other frequency bands. PSR J1909-3744 shows the lowest levels of jitter noise, which we estimate to contribute $\\sim$10 ns root mean square error to the arrival times for hour-duration observati...

  7. Energy calibration of CsI(Tl) scintillator in pulse-shape identification technique

    CERN Document Server

    Avdeichikov, V; Golubev, P; Jakobsson, B; Colonna, N

    2003-01-01

    A batch of 16 CsI(Tl) scintillator crystals, supplied by the Bicron Company, has been studied with respect to precise energy calibration in pulse-shape identification technique. The light corresponding to pulse integration within the time interval 1.6-4.5 mu s (long gate) and 0.0-4.5 mu s (extra-long gate) exhibits a power law relation, L(E,Z,A)=a1(Z,A)E sup a sup 2 sup ( sup Z sup , sup A sup ) , for sup 1 sup , sup 2 sup , sup 3 H isotopes in the measured energy range 5-150 MeV. For the time interval 0.0-0.60 mu s (short gate), a significant deviation from the power law relation is observed, for energy greater than approx 30 MeV. The character of the a2(p)-a2(d) and a2(p)-a2(t) correlations for protons, deuterons and tritons, reveals 3 types of crystals in the batch. These subbatches differ in the value of the extracted parameter a2 for protons, and in the value of the spread of a2 for deuterons and tritons. This may be explained by the difference in the energy dependence of the fast decay time component an...

  8. New opportunities for secure communication networks using shaped femtosecond laser pulses inducing filamentation processes in the atmosphere

    Science.gov (United States)

    Alyami, H. M.; Becerra, V. M.; Hadjiloucas, S.

    2013-11-01

    The current study discusses new opportunities for secure ground to satellite communications using shaped femtosecond pulses that induce spatial hole burning in the atmosphere for efficient communications with data encoded within super-continua generated by femtosecond pulses. Refractive index variation across the different layers in the atmosphere may be modelled using assumptions that the upper strata of the atmosphere and troposphere behaving as layered composite amorphous dielectric networks composed of resistors and capacitors with different time constants across each layer. Input-output expressions of the dynamics of the networks in the frequency domain provide the transmission characteristics of the propagation medium. Femtosecond pulse shaping may be used to optimize the pulse phase-front and spectral composition across the different layers in the atmosphere. A generic procedure based on evolutionary algorithms to perform the pulse shaping is proposed. In contrast to alternative procedures that would require ab initio modelling and calculations of the propagation constant for the pulse through the atmosphere, the proposed approach is adaptive, compensating for refractive index variations along the column of air between the transmitter and receiver.

  9. A Comparison between Electrical and Optical Chromatic Dispersion Compensation in Wavelength Divison Multiplexing Network Regarding to Electrical Pulse Shapes

    Directory of Open Access Journals (Sweden)

    Mohammad S. Ab-Rahman

    2012-01-01

    Full Text Available Problem statement: Besides of some impairment that has been inherited form single channel, specialists confronted with new obstacles in WDM implementation which bared them for achieving desired performance. Although Chromatic Dispersion (CD exists in single channel too, it can worsens new nonlinearities which are occurs just in WDM systems. So CD compensation in WDM is even more vital than single channel one. Approach: A wide range of optical and electrical CD compensation techniques have been represented. In this study we evaluate the efficiency of feed Forward-Decision Feedback Equalizer (FFE-DFE as one type of electrical compensation methods and Dispersion Compensation Fiber as one type of optical compensator. Also we will look how electrical pulse shapes induced by pulse generator in transmitter, can impact on the performance of the either optical or electrical compensations. Results: After implementation, it was revealed that overall optical compensation with DCF gives us better performance than electrical equalizer and NRZ is more vulnerable than two other pulse shapes. Conclusion: Chromatic compensation was implemented with different pulse shapes and RZ pulse shape with optical compensation showed the best performance.

  10. Radial position of single-site gamma-ray interactions from a parametric pulse shape analysis of germanium detector signals

    CERN Document Server

    Orrell, J L; Cooper, M W; Kephart, J D; Seifert, C E; Orrell, John L.; Aalseth, Craig E.; Cooper, Matthew W.; Kephart, Jeremy D.; Seifert, Carolyn E.

    2007-01-01

    Pulse shape analysis of germanium gamma-ray spectrometer signals can yield information on the radial position of individual gamma-ray interactions within the germanium crystal. A parametric pulse shape analysis based on calculation of moments of the reconstructed current pulses from a closed-ended coaxial germanium detector is used to preferentially select single-site gamma-ray interactions. The double escape peak events from the 2614.5 keV gamma-ray of 208-Tl are used as a training set to optimize the single-site event selection region in the pulse shape parameter space. A collimated source of 320.1 keV gamma-rays from 51-Cr is used to scan different radial positions of the same semi-coaxial germanium detector. The previously trained single-site selection region is used to preferentially identify the single-site photoelectric absorption events from the 320.1 keV full-energy peak. From the identified events, a comparison of the pulse shape parameter space distributions between different scan positions allows ...

  11. Objective estimation of body condition score by modeling cow body shape from digital images.

    Science.gov (United States)

    Azzaro, G; Caccamo, M; Ferguson, J D; Battiato, S; Farinella, G M; Guarnera, G C; Puglisi, G; Petriglieri, R; Licitra, G

    2011-04-01

    Body condition score (BCS) is considered an important tool for management of dairy cattle. The feasibility of estimating the BCS from digital images has been demonstrated in recent work. Regression machines have been successfully employed for automatic BCS estimation, taking into account information of the overall shape or information extracted on anatomical points of the shape. Despite the progress in this research area, such studies have not addressed the problem of modeling the shape of cows to build a robust descriptor for automatic BCS estimation. Moreover, a benchmark data set of images meant as a point of reference for quantitative evaluation and comparison of different automatic estimation methods for BCS is lacking. The main objective of this study was to develop a technique that was able to describe the body shape of cows in a reconstructive way. Images, used to build a benchmark data set for developing an automatic system for BCS, were taken using a camera placed above an exit gate from the milking robot. The camera was positioned at 3 m from the ground and in such a position to capture images of the rear, dorsal pelvic, and loin area of cows. The BCS of each cow was estimated on site by 2 technicians and associated to the cow images. The benchmark data set contained 286 images with associated BCS, anatomical points, and shapes. It was used for quantitative evaluation. A set of example cow body shapes was created. Linear and polynomial kernel principal component analysis was used to reconstruct shapes of cows using a linear combination of basic shapes constructed from the example database. In this manner, a cow's body shape was described by considering her variability from the average shape. The method produced a compact description of the shape to be used for automatic estimation of BCS. Model validation showed that the polynomial model proposed in this study performs better (error=0.31) than other state-of-the-art methods in estimating BCS even at the

  12. Communication: Analytical optimal pulse shapes obtained with the aid of genetic algorithms: Controlling the photoisomerization yield of retinal

    Science.gov (United States)

    Guerrero, R. D.; Arango, C. A.; Reyes, A.

    2016-07-01

    We recently proposed a Quantum Optimal Control (QOC) method constrained to build pulses from analytical pulse shapes [R. D. Guerrero et al., J. Chem. Phys. 143(12), 124108 (2015)]. This approach was applied to control the dissociation channel yields of the diatomic molecule KH, considering three potential energy curves and one degree of freedom. In this work, we utilized this methodology to study the strong field control of the cis-trans photoisomerization of 11-cis retinal. This more complex system was modeled with a Hamiltonian comprising two potential energy surfaces and two degrees of freedom. The resulting optimal pulse, made of 6 linearly chirped pulses, was capable of controlling the population of the trans isomer on the ground electronic surface for nearly 200 fs. The simplicity of the pulse generated with our QOC approach offers two clear advantages: a direct analysis of the sequence of events occurring during the driven dynamics, and its reproducibility in the laboratory with current laser technologies.

  13. Shaping perfect optical vortex with amplitude modulated using a digital micro-mirror device

    Science.gov (United States)

    Zhang, Chonglei; Min, Changjun; Yuan, X.-C.

    2016-12-01

    We propose a technique to generate of perfect optical vortex (POV) via Fourier transformation of Bessel-Gauss (BG) beams through encoding of the amplitude of the optical field with binary amplitude digital micro-mirrors device (DMD). Furthermore, we confirm the correct phase patterns of the POV with the method of Mach-Zehnder interferometer. Our approach to generate the POV has the advantages that rapidly switch among the different modes, wide spectral regions and high energy tolerance. Since the POV possess propagation properties that not shape-invariant, we therefore suppose that our proposed approach will find potential applications in optical microscopy, optical fabrication, and optical communication.

  14. Pulse width modulation-based temperature tracking for feedback control of a shape memory alloy actuator.

    Science.gov (United States)

    Ayvali, Elif; Desai, Jaydev P

    2014-04-01

    This work presents a temperature-feedback approach to control the radius of curvature of an arc-shaped shape memory alloy (SMA) wire. The nonlinear properties of the SMA such as phase transformation and its dependence on temperature and stress make SMA actuators difficult to control. Tracking a desired trajectory is more challenging than controlling just the position of the SMA actuator since the desired path is continuously changing. Consequently, tracking the desired strain directly or tracking the parameters such as temperature and electrical resistance that are related to strain with a model is a challenging task. Temperature-feedback is an attractive approach when direct measurement of strain is not practical. Pulse width modulation (PWM) is an effective method for SMA actuation and it can be used along with a compensator to control the temperature of the SMA. Using the constitutive model of the SMA, the desired temperature profile can be obtained for a given strain trajectory. A PWM-based nonlinear PID controller with a feed-forward heat transfer model is proposed to use temperature-feedback for tracking a desired temperature trajectory. The proposed controller is used during the heating phase of the SMA actuator. The controller proves to be effective in tracking step-wise and continuous trajectories.

  15. Matrix shaped pulsed laser deposition: New approach to large area and homogeneous deposition

    Energy Technology Data Exchange (ETDEWEB)

    Akkan, C.K.; May, A. [INM – Leibniz Institute for New Materials, CVD/Biosurfaces Group, Campus D2 2, 66123 Saarbrücken (Germany); Hammadeh, M. [Department for Obstetrics, Gynecology and Reproductive Medicine, IVF Laboratory, Saarland University Medical Center and Faculty of Medicine, Building 9, 66421 Homburg, Saar (Germany); Abdul-Khaliq, H. [Clinic for Pediatric Cardiology, Saarland University Medical Center and Faculty of Medicine, Building 9, 66421 Homburg, Saar (Germany); Aktas, O.C., E-mail: cenk.aktas@inm-gmbh.de [INM – Leibniz Institute for New Materials, CVD/Biosurfaces Group, Campus D2 2, 66123 Saarbrücken (Germany)

    2014-05-01

    Pulsed laser deposition (PLD) is one of the well-established physical vapor deposition methods used for synthesis of ultra-thin layers. Especially PLD is suitable for the preparation of thin films of complex alloys and ceramics where the conservation of the stoichiometry is critical. Beside several advantages of PLD, inhomogeneity in thickness limits use of PLD in some applications. There are several approaches such as rotation of the substrate or scanning of the laser beam over the target to achieve homogenous layers. On the other hand movement and transition create further complexity in process parameters. Here we present a new approach which we call Matrix Shaped PLD to control the thickness and homogeneity of deposited layers precisely. This new approach is based on shaping of the incoming laser beam by a microlens array and a Fourier lens. The beam is split into much smaller multi-beam array over the target and this leads to a homogenous plasma formation. The uniform intensity distribution over the target yields a very uniform deposit on the substrate. This approach is used to deposit carbide and oxide thin films for biomedical applications. As a case study coating of a stent which has a complex geometry is presented briefly.

  16. Further study of CdWO4 crystal scintillators as detectors for high sensitivity double beta experiments: scintillation properties and pulse-shape discrimination

    CERN Document Server

    Bardelli, L; Bizzeti, P G; Carraresi, L; Danevich, F A; Fazzini, T F; Grinyov, B V; Ivannikova, N V; Kobychev, V V; Kropivyansky, B N; Maurenzig, P R; Nagornaya, L L; Nagorny, S S; Nikolaiko, A S; Pavlyuk, A A; Poda, D V; Solsky, I M; Sopinskyy, M V; Stenin, Y G; Taccetti, F; Tretyak, V I; Vasiliev, Y V; Yurchenko, S S; Stenin, Yu. G.; Vasiliev, Ya. V.

    2006-01-01

    Energy resolution, light yield, non-proportionality in the scintillation response, alpha/beta ratio, pulse shape for gamma rays and alpha particles were studied with CdWO4 crystal scintillators. Some indication for a difference in the emission spectra for gamma rays and alpha particles was observed. No dependence of CdWO4 pulse shape on emission spectrum wavelengths under laser, alpha particles and gamma ray excitation was observed. Dependence of scintillation pulse shape for gamma quanta and alpha particles and pulse-shape discrimination ability on temperature was measured in the range of 0-24 degrees.

  17. Further study of CdWO{sub 4} crystal scintillators as detectors for high sensitivity 2{beta} experiments: Scintillation properties and pulse-shape discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Bardelli, L. [Dipartimento di Fisica, Universita di Firenze and INFN, 50019 Florence (Italy); Bini, M. [Dipartimento di Fisica, Universita di Firenze and INFN, 50019 Florence (Italy); Bizzeti, P.G. [Dipartimento di Fisica, Universita di Firenze and INFN, 50019 Florence (Italy); Carraresi, L. [Dipartimento di Fisica, Universita di Firenze and INFN, 50019 Florence (Italy); Danevich, F.A. [Institute for Nuclear Research, MSP 03680 Kiev (Ukraine)]. E-mail: danevich@kinr.kiev.ua; Fazzini, T.F. [Dipartimento di Fisica, Universita di Firenze and INFN, 50019 Florence (Italy); Grinyov, B.V. [Institute for Scintillation Materials, 61001 Kharkov (Ukraine); Ivannikova, N.V. [Nikolaev Institute of Inorganic Chemistry, 630090 Novosibirsk (Russian Federation); Kobychev, V.V. [Institute for Nuclear Research, MSP 03680 Kiev (Ukraine); Kropivyansky, B.N. [Institute for Nuclear Research, MSP 03680 Kiev (Ukraine); Maurenzig, P.R. [Dipartimento di Fisica, Universita di Firenze and INFN, 50019 Florence (Italy); Nagornaya, L.L. [Institute for Scintillation Materials, 61001 Kharkov (Ukraine); Nagorny, S.S. [Institute for Nuclear Research, MSP 03680 Kiev (Ukraine); Nikolaiko, A.S. [Institute for Nuclear Research, MSP 03680 Kiev (Ukraine); Pavlyuk, A.A. [Nikolaev Institute of Inorganic Chemistry, 630090 Novosibirsk (Russian Federation); Poda, D.V. [Institute for Nuclear Research, MSP 03680 Kiev (Ukraine); Solsky, I.M. [Institute for Materials, 79031 Lviv (Ukraine); Sopinskyy, M.V. [Lashkaryov Institute of Semiconductor Physics, 03028 Kiev (Ukraine); Stenin, Yu.G. [Nikolaev Institute of Inorganic Chemistry, 630090 Novosibirsk (Russian Federation); Taccetti, F. [Dipartimento di Fisica, Universita di Firenze and INFN, 50019 Florence (Italy); Tretyak, V.I.; Yurchenko, S.S. [Institute for Nuclear Research, MSP 03680 Kiev (Ukraine); Vasiliev, Ya.V. [Nikolaev Institute of Inorganic Chemistry, 630090 Novosibirsk (Russian Federation)

    2006-12-21

    Energy resolution, non-proportionality in the scintillation response, {alpha}/{beta} ratio, pulse shape for {gamma} rays and {alpha} particles were studied with CdWO{sub 4} crystal scintillators. Some indication for a difference in the emission spectra for {gamma} rays and {alpha} particles was observed. No dependence of CdWO{sub 4} pulse shape on emission spectrum wavelengths under laser, {alpha} particles and {gamma} ray excitation was observed. Dependence of scintillation pulse shape for {gamma} quanta and {alpha} particles and pulse-shape discrimination ability on temperature was measured in the range of 0-24{sup o}C.

  18. EFFECT OF DIGITAL BLOCK ON SPAO2, LAG TIME AND HEIGHT OF PLETHYSMOGRAPHIC WAYE OF PULSE OXIMETER BY SIMULATED SHOCK

    Directory of Open Access Journals (Sweden)

    K TAVAKKOL

    2002-06-01

    Full Text Available Introduction. Pulse oximetry is impaired by hypotention and peripheral vasoconstriction. Digital block may cause to increase tissue perfusion and improve the parameters of pulse oximetry. The purpose of this study was to investigate the effect of digital block on SPa02, lag time and height of plethysmographic wave of pulse oximeter by simulated shock in upper extrimity. Methods. In an experimental study, 34 Paitents under general anesthesia and elective surgery were selected. Lag time and height of pletysmographic wave and SPa02 had been measured in two fingers shocked by cooling, elevation of hand and inflation of cuff; then, compared to opposite middle finger as control. shocked Middle finger were blocked by lidocaine 2% and these parameters were measured in the 15th and 20th minutes after digital block. Data analysis was performed by SPSS using ANOVA. Results. Mean height of plethysmographic wave in blocked finger was signihcontly taller than shocked and control fingers in the 15th minute (respectively, 16.9±6, 10.8 ± 4. 3,10.7 ± 4.3, P < 0.05 and the 20th minute afters digital block (21.1 ± 5.8, 11.8 ± 4.3, 11.2 ± 3.9, P < 0.05. There were not significalt differences between three fingers in lag time and SPa02. Discussion. This study documents effect of digital block, undergoing shock condition in improving the parameters of pulse oximetry.

  19. Towards Terawatt Sub-Cycle Long-Wave Infrared Pulses via Chirped Optical Parametric Amplification and Indirect Pulse Shaping

    Science.gov (United States)

    Yin, Yanchun; Chew, Andrew; Ren, Xiaoming; Li, Jie; Wang, Yang; Wu, Yi; Chang, Zenghu

    2017-04-01

    We present an approach for both efficient generation and amplification of 4-12 μm pulses by tailoring the phase matching of the nonlinear crystal Zinc Germanium Phosphide (ZGP) in a narrowband-pumped optical parametric chirped pulse amplifier (OPCPA) and a broadband-pumped dual-chirped optical parametric amplifier (DC-OPA), respectively. Preliminary experimental results are obtained for generating 1.8-4.2 μm super broadband spectra, which can be used to seed both the signal of the OPCPA and the pump of the DC-OPA. The theoretical pump-to-idler conversion efficiency reaches 27% in the DC-OPA pumped by a chirped broadband Cr2+:ZnSe/ZnS laser, enabling the generation of  Terawatt-level 4-12 μm pulses with an available large-aperture ZGP. Furthermore, the 4-12 μm idler pulses can be compressed to sub-cycle pulses by compensating the tailored positive chirp of the idler pulses using the bulk compressor NaCl, and by indirectly controlling the higher-order idler phase through tuning the signal (2.4-4.0 μm) phase with a commercially available acousto-optic programmable dispersive filter (AOPDF). A similar approach is also described for generating high-energy 4-12 μm sub-cycle pulses via OPCPA pumped by a 2 μm Ho:YLF laser.

  20. Shape determination of microcalcifications in simulated digital mammography images with varying pixel size

    Science.gov (United States)

    Ruschin, Mark; Bath, Magnus; Hemdal, Bengt; Tingberg, Anders

    2005-04-01

    The purpose of this work was to study how the pixel size of digital detectors can affect shape determination of microcalcifications in mammography. Screen-film mammograms containing microcalcifications clinically proven to be indicative of malignancy were digitised at 100 lines/mm using a high-resolution Tango drum scanner. Forty microcalcifications were selected to cover an appropriate range of sizes, shapes and contrasts typically found of malignant cases. Based on the measured MTF and NPS of the combined screen-film and scanner system, these digitised images were filtered to simulate images acquired with a square sampling pixel size of 10 μm x 10 μm and a fill factor of one. To simulate images acquired with larger pixel sizes, these finely sampled images were re-binned to yield a range of effective pixel sizes from 20 μm up to 140 μm. An alternative forced-choice (AFC) observer experiment was conducted with eleven observers for this set of digitised microcalcifications to determine how pixel size affects the ability to discriminate shape. It was found that observer score increased with decreasing pixel size down to 60 μm (p<0.01), at which point no significant advantage was obtained by using smaller pixel sizes due to the excessive relative noise-per-pixel. The relative gain in shape discrimination ability at smaller pixel sizes was larger for microcalcifications that were smaller than 500 μm and circular.

  1. Comparison of charged particle identification using pulse shape discrimination and ΔE−E methods between front and rear side injection in silicon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Le Neindre, N., E-mail: leneindre@lpccaen.in2p3.fr [LPC, IN2P3-CNRS, ENSICAEN et Université de Caen, F-14050 Caen Cedex (France); Bougault, R. [LPC, IN2P3-CNRS, ENSICAEN et Université de Caen, F-14050 Caen Cedex (France); Barlini, S. [INFN e Università di Firenze, via G.Sansone 1, 50019 Sesto Fiorentino (Firenze) (Italy); Bonnet, E. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 5027, F-14076 Caen Cedex (France); Borderie, B. [Institut de Physique Nucléaire, CNRS/IN2P3, Université Paris-Sud 11, F-91406 Orsay Cedex (France); Casini, G. [INFN sezione di Firenze, via G.Sansone 1, 50019 Sesto Fiorentino (Firenze) (Italy); Chbihi, A. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 5027, F-14076 Caen Cedex (France); Edelbruck, P. [Institut de Physique Nucléaire, CNRS/IN2P3, Université Paris-Sud 11, F-91406 Orsay Cedex (France); Frankland, J.D.; Gruyer, D. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 5027, F-14076 Caen Cedex (France); Legouée, E.; Lopez, O. [LPC, IN2P3-CNRS, ENSICAEN et Université de Caen, F-14050 Caen Cedex (France); Marini, P. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 5027, F-14076 Caen Cedex (France); Pârlog, M. [LPC, IN2P3-CNRS, ENSICAEN et Université de Caen, F-14050 Caen Cedex (France); Horia Hulubei, National Institute of Physics and Nuclear Engineering, RO-077125 Bucharest-Măgurele (Romania); Pasquali, G. [INFN e Università di Firenze, via G.Sansone 1, 50019 Sesto Fiorentino (Firenze) (Italy); Petcu, M. [Horia Hulubei, National Institute of Physics and Nuclear Engineering, RO-077125 Bucharest-Măgurele (Romania); and others

    2013-02-11

    The response of silicon–silicon–CsI(Tl) telescopes, developed within the FAZIA collaboration, to fragments produced in nuclear reactions {sup 84}Kr+{sup 120-124}Sn at 35 A MeV, has been used to study ion identification methods. Two techniques are considered for the identification of the nuclear products in the silicon stages. The standard ΔE−E one requires signals induced in two detection layers by ions punching through the first one. Conversely, the digital Pulse Shape Analysis (PSA) allows the identification of ions stopped in the first silicon layer. The capabilities of these two identification methods have been compared for different mountings of the silicons, i.e. rear (particles entering through the low electric field side) or front (particles entering through the high electric field side) side injection. The ΔE−E identification method gives exactly the same results in both configurations. At variance, the pulse shape discrimination is very sensitive to the detector mounting. In case of rear side injection, the identification with the “energy vs. charge rise time” PSA method presents energy thresholds which are significantly lower than in the case of front side injection.

  2. Comparison of charged particle identification using pulse shape discrimination and ΔE-E methods between front and rear side injection in silicon detectors

    Science.gov (United States)

    Le Neindre, N.; Bougault, R.; Barlini, S.; Bonnet, E.; Borderie, B.; Casini, G.; Chbihi, A.; Edelbruck, P.; Frankland, J. D.; Gruyer, D.; Legouée, E.; Lopez, O.; Marini, P.; Pârlog, M.; Pasquali, G.; Petcu, M.; Rivet, M. F.; Salomon, F.; Vient, E.; Alba, R.; Baiocco, G.; Bardelli, L.; Bini, M.; Borcea, R.; Bruno, M.; Carboni, S.; Cinausero, M.; Cruceru, I.; Degerlier, M.; Dueñas, J. A.; GaŞior, K.; Gramegna, F.; Grzeszczuk, A.; Kamuda, M.; Kozik, T.; Kravchuk, V.; Lombardo, I.; Maiolino, C.; Marchi, T.; Morelli, L.; Negoita, F.; Olmi, A.; Petrascu, H.; Piantelli, S.; Poggi, G.; Rosato, E.; Santonocito, D.; Spadaccini, G.; Stefanini, A. A.; Twaróg, T.; Vigilante, M.; Fazia Collaboration

    2013-02-01

    The response of silicon-silicon-CsI(Tl) telescopes, developed within the FAZIA collaboration, to fragments produced in nuclear reactions 84Kr+120-124Sn at 35 A MeV, has been used to study ion identification methods. Two techniques are considered for the identification of the nuclear products in the silicon stages. The standard ΔE-E one requires signals induced in two detection layers by ions punching through the first one. Conversely, the digital Pulse Shape Analysis (PSA) allows the identification of ions stopped in the first silicon layer. The capabilities of these two identification methods have been compared for different mountings of the silicons, i.e. rear (particles entering through the low electric field side) or front (particles entering through the high electric field side) side injection. The ΔE-E identification method gives exactly the same results in both configurations. At variance, the pulse shape discrimination is very sensitive to the detector mounting. In case of rear side injection, the identification with the “energy vs. charge rise time” PSA method presents energy thresholds which are significantly lower than in the case of front side injection.

  3. LaBr{sub 3}(Ce):LaCl{sub 3}(Ce) Phoswich with pulse shape analysis for high energy gamma-ray and proton identification

    Energy Technology Data Exchange (ETDEWEB)

    Tengblad, O., E-mail: olof.tengblad@csic.es [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Nilsson, T. [Department of Fundamental Physics, Chalmers University of Technology, S-41296 Göteborg (Sweden); Nácher, E. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Johansson, H.T. [Department of Fundamental Physics, Chalmers University of Technology, S-41296 Göteborg (Sweden); Briz, J.A.; Carmona-Gallardo, M.; Cruz, C.; Gugliermina, V.; Perea, A.; Sanchez del Rio, J.; Turrión Nieves, M. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Bergström, J.; Blomberg, E.; Bülling, A.; Gallneby, E.; Hagdahl, J.; Jansson, L.; Jareteg, K.; Masgren, R.; Nordström, M. [Department of Fundamental Physics, Chalmers University of Technology, S-41296 Göteborg (Sweden); and others

    2013-03-11

    A novel Phoswich design based on new generation scintillator crystals is presented. The detector composed from a combination of a LaBr{sub 3}(Ce) with a LaCl{sub 3}(Ce) crystal in one cylinder coupled to a photo multiplier tube has been tested both for incident gamma rays in the range of 0.3–6 MeV, as well as for high energy protons in the range 120–180 MeV. The Phoswich assembly has not significantly deteriorated the energy resolution, which for 662 KeV gamma rays gives a resolution of 4.5%, while for high energy protons (E{sub p}=180 MeV) an energy resolution of 1% was obtained. It is shown that the signals from the two crystals can be separated in an event by event based mode. Using direct digitizing of the detector pulse an off-line pulse-shape analysis was performed built either on a total to tail or total to pulse height method in order to fully identify the incoming radiation. Our aim with this R and D is to in the future build a detector which is able to detect with good efficiency and resolution over a wide energy range; 0.1–30 MeV gamma rays and 20–400 MeV protons. Monte Carlo simulations made in order to design the next prototype are presented.

  4. Generating shaped femtosecond pulses in the far infrared using a spatial light modulator and difference frequency generation

    CSIR Research Space (South Africa)

    Botha, N

    2010-08-31

    Full Text Available , Ch, Sharpe-Tudoran, C, Winter, M. & Baumert, T. 2003. Compact, robust, and flexible setup for femtosecond pulse shaping. Review of scientific instruments, 75:4950-4953. 3. Cavallari, M, Gale, G.M, Hache, F, Pavlov, L.I & Rousseau, E 1995. Mid infra...

  5. Pulse shaping for high data rate ultra-wideband wireless transmission under the Russian spectral emission mask

    DEFF Research Database (Denmark)

    Rommel, Simon; Grakhova, Elizaveta P.; Jurado-Navas, Antonio

    2017-01-01

    This paper addresses impulse-radio ultra-wideband (IR-UWB) transmission under the Russian spectral emission mask for unlicensed UWB radio communications. Four pulse shapes are proposed and their bit error rate (BER) performance is both estimated analytically and evaluated experimentally. Well-kno...

  6. Implementation of a SVWP-based laser beam shaping technique for generation of 100-mJ-level picosecond pulses.

    Science.gov (United States)

    Adamonis, J; Aleknavičius, A; Michailovas, K; Balickas, S; Petrauskienė, V; Gertus, T; Michailovas, A

    2016-10-01

    We present implementation of the energy-efficient and flexible laser beam shaping technique in a high-power and high-energy laser amplifier system. The beam shaping is based on a spatially variable wave plate (SVWP) fabricated by femtosecond laser nanostructuring of glass. We reshaped the initially Gaussian beam into a super-Gaussian (SG) of the 12th order with efficiency of about 50%. The 12th order of the SG beam provided the best compromise between large fill factor, low diffraction on the edges of the active media, and moderate intensity distribution modification during free-space propagation. We obtained 150 mJ pulses of 532 nm radiation. High-energy, pulse duration of 85 ps and the nearly flat-top spatial profile of the beam make it ideal for pumping optical parametric chirped pulse amplification systems.

  7. Digital quantification of rolling circle amplified single DNA molecules in a resistive pulse sensing nanopore.

    Science.gov (United States)

    Kühnemund, M; Nilsson, M

    2015-05-15

    Novel portable, sensitive and selective DNA sensor methods for bio-sensing applications are required that can rival conventionally used non-portable and expensive fluorescence-based sensors. In this paper, rolling circle amplification (RCA) products are detected in solution and on magnetic particles using a resistive pulse sensing (RPS) nanopore. Low amounts of DNA molecules are detected by padlock probes which are circularized in a strictly target dependent ligation reaction. The DNA-padlock probe-complex is captured on magnetic particles by sequence specific capture oligonucleotides and amplified by a short RCA. Subsequent RPS analysis is used to identify individual particles with single attached RCA products from blank particles. This proof of concept opens up for a novel non-fluorescent digital DNA quantification method that can have many applications in bio-sensing and diagnostic approaches.

  8. Effects of Pulse Density on Digital Terrain Models and Canopy Metrics Using Airborne Laser Scanning in a Tropical Rainforest

    Directory of Open Access Journals (Sweden)

    Endre Hofstad Hansen

    2015-06-01

    Full Text Available Airborne laser scanning (ALS is increasingly being used to enhance the accuracy of biomass estimates in tropical forests. Although the technological development of ALS instruments has resulted in ever-greater pulse densities, studies in boreal and sub-boreal forests have shown consistent results even at relatively small pulse densities. The objective of the present study was to assess the effects of reduced pulse density on (1 the digital terrain model (DTM, and (2 canopy metrics derived from ALS data collected in a tropical rainforest in Tanzania. We used a total of 612 coordinates measured with a differential dual frequency Global Navigation Satellite System receiver to analyze the effects on DTMs at pulse densities of 8, 4, 2, 1, 0.5, and 0.025 pulses·m−2. Furthermore, canopy metrics derived for each pulse density and from four different field plot sizes (0.07, 0.14, 0.21, and 0.28 ha were analyzed. Random variation in DTMs and canopy metrics increased with reduced pulse density. Similarly, increased plot size reduced variation in canopy metrics. A reliability ratio, quantifying replication effects in the canopy metrics, indicated that most of the common metrics assessed were reliable at pulse densities >0.5 pulses·m−2 at a plot size of 0.07 ha.

  9. Dynamic feedback circuits function as a switch for shaping a maturation-inducing steroid pulse in Drosophila

    Science.gov (United States)

    Moeller, Morten E.; Danielsen, E. Thomas; Herder, Rachel; O’Connor, Michael B.; Rewitz, Kim F.

    2013-01-01

    Steroid hormones trigger the onset of sexual maturation in animals by initiating genetic response programs that are determined by steroid pulse frequency, amplitude and duration. Although steroid pulses coordinate growth and timing of maturation during development, the mechanisms generating these pulses are not known. Here we show that the ecdysone steroid pulse that drives the juvenile-adult transition in Drosophila is determined by feedback circuits in the prothoracic gland (PG), the major steroid-producing tissue of insect larvae. These circuits coordinate the activation and repression of hormone synthesis, the two key parameters determining pulse shape (amplitude and duration). We show that ecdysone has a positive-feedback effect on the PG, rapidly amplifying its own synthesis to trigger pupariation as the onset of maturation. During the prepupal stage, a negative-feedback signal ensures the decline in ecdysone levels required to produce a temporal steroid pulse that drives developmental progression to adulthood. The feedback circuits rely on a developmental switch in the expression of Broad isoforms that transcriptionally activate or silence components in the ecdysone biosynthetic pathway. Remarkably, our study shows that the same well-defined genetic program that stimulates a systemic downstream response to ecdysone is also utilized upstream to set the duration and amplitude of the ecdysone pulse. Activation of this switch-like mechanism ensures a rapid, self-limiting PG response that functions in producing steroid oscillations that can guide the decision to terminate growth and promote maturation. PMID:24173800

  10. Scintillation-only Based Pulse Shape Discrimination for Nuclear and Electron Recoils in Liquid Xenon

    CERN Document Server

    Ueshima, K; Hiraide, K; Hirano, S; Kishimoto, Y; Kobayashi, K; Koshio, Y; Liu, J; Martens, K; Moriyama, S; Nakahata, M; Nishiie, H; Ogawa, H; Sekiya, H; Shinozaki, A; Suzuki, Y; Takeda, A; Yamashita, M; Fujii, K; Murayama, I; Nakamura, S; Otsuka, K; Takeuchi, Y; Fukuda, Y; Nishijima, K; Motoki, D; Itow, Y; Masuda, K; Nishitani, Y; Uchida, H; Tasaka, S; Ohsumi, H; Kim, Y D; Kim, Y H; Lee, K B; Lee, M K

    2011-01-01

    In a dedicated test setup at the Kamioka Observatory we studied pulse shape discrimination (PSD) in liquid xenon (LXe) for dark matter searches. PSD in LXe was based on the observation that scintillation light from electron events was emitted over a longer period of time than that of nuclear recoil events, and our method used a simple ratio of early to total scintillation light emission in a single scintillation event. Requiring an efficiency of 50% for nuclear recoil retention we reduced the electron background to 7.7\\pm1.1(stat)\\pm1.2 0.6(sys)\\times10-2 at energies between 4.8 and 7.2 keVee and to 7.7\\pm2.8(stat)\\pm2.5 2.8(sys)\\times10-3 at energies between 9.6 and 12 keVee for a scintillation light yield of 20.9 p.e./keV. Further study was done by masking some of that light to reduce this yield to 4.6 p.e./keV, the same method results in an electron event reduction of 2.4\\pm0.2(stat)\\pm0.3 0.2(sys)\\times10-1 for the lower of the energy regions above. We also observe that in contrast to nuclear recoils the ...

  11. The pulse shape of cosmic-ray ground-level enhancements

    CERN Document Server

    Moraal, H; Caballero-Lopez, R A

    2016-01-01

    Enhancements of the comic-ray intensity as observed by detectors on the ground have been observed 71 times since 1942. They are due to solar energetic particles accelerated in the regions of solar flares deep in the corona, or in the shock front of coronal mass ejections (CMEs) in the solar wind. The latter is the favoured model for the classical gradual ground-level enhancement (GLE). In several papers since the one of McCracken et al. (2008), we pointed out, however, that some GLEs are too impulsive to be accelerated in the CME shocks. With this hypothesis in mind we study the time profiles of all the available GLEs. The main results are that there is a continuous range from gradual to impulsive, that the fastest risers are concentrated at heliolongitudes that are magnetically well-connected to Earth, and that the shape of the pulse is a powerful indicator of propagation conditions between Sun and Earth. This ranges from relatively quiet to highly disturbed.

  12. Correction for hole trapping in AGATA detectors using pulse shape analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bruyneel, B. [CEA Saclay, DSM/IRFU/SPhN, Gif-sur-Yvette Cedex (France); Universitaet zu Koeln, Institut fuer Kernphysik, Koeln (Germany); Birkenbach, B.; Eberth, J.; Hess, H.; Pascovici, Gh.; Reiter, P.; Wiens, A. [Universitaet zu Koeln, Institut fuer Kernphysik, Koeln (Germany); Bazzacco, D.; Farnea, E.; Michelagnoli, C.; Recchia, F. [INFN, Sezione di Padova, Padova (Italy); Collaboration: for the AGATA Collaboration

    2013-05-15

    Data from the highly segmented High-Purity Germanium (HPGe) detectors of the AGATA spectrometer show that segments are more sensitive to neutron damage than the central core contact. Calculations on the collection efficiency of charge carriers inside the HPGe detector were performed in order to understand this phenomenon. The trapping sensitivity, an expression based on the collection efficiencies for electrons and holes, is put forward to quantify the effect of charge carrier trapping. The sensitivity is evaluated for each position in the detector volume with respect to the different electrodes and the collected charge carrier type. Using the position information obtained by pulse shape analysis from the position-sensitive AGATA detectors, it is possible to correct for the energy deficit employing detector specific sensitivity values. We report on the successful correction of the energy peaks from heavily neutron-damaged AGATA detectors for core and segment electrode signals. The original energy resolution can optimally be recovered up to a certain quantifiable limit of degradation due to statistical fluctuations caused by trapping effects. (orig.)

  13. A fast and powerful release mechanism based on pulse heating of shape memory wires

    Science.gov (United States)

    Malka, Yoav; Shilo, Doron

    2017-09-01

    This article presents a novel actuator and a new concept for a release mechanism that are especially useful in applications that require fast motion of large masses over long distances. The actuator is based on ultra-fast pulse heating of NiTi wires, which provide a unique combination of large work per volume, short response time and enhanced energy efficiency. The release mechanism utilizes the fast and powerful actuator to form conditions in which the latch (safety pin) moves faster than the deployed device. As a result, the contact between these two masses is disconnected and the resulting friction forces are decreased to approximately zero. The actuator and release mechanism address the two major drawbacks of conventional shape memory alloy (SMA) actuators: slow actuation time and low energy efficiency. Using a dedicated setup, the experimental results validate the disconnection between the masses and map the effects of several variables on the performance of the actuator and release mechanism. In particular, we map the energetic efficiency and find the optimal operating conditions for a successful release using a minimal amount of input energy. At the optimal conditions, the actuator response time and the consumed input energy are smaller by an order of magnitude with respect to performances of previous SMA-based release mechanisms with comparable requirements.

  14. Fast neutron tomography with real-time pulse-shape discrimination in organic scintillation detectors

    Science.gov (United States)

    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.

  15. Neutron/gamma pulse shape discrimination in plastic scintillators: Preparation and characterization of various compositions

    Energy Technology Data Exchange (ETDEWEB)

    Blanc, Pauline [CEA, LIST, Laboratoire Capteurs et Architectures Électroniques, F-91191 Gif-sur-Yvette (France); Laboratoire de Photophysique et Photochimie Supramoléculaires et Macromoléculaires (CNRS UMR 8531), École Normale Supérieure de Cachan, 61 Avenue du Président Wilson, F-94235 Cachan cedex (France); Hamel, Matthieu, E-mail: matthieu.hamel@cea.fr [CEA, LIST, Laboratoire Capteurs et Architectures Électroniques, F-91191 Gif-sur-Yvette (France); Dehé-Pittance, Chrystèle; Rocha, Licinio [CEA, LIST, Laboratoire Capteurs et Architectures Électroniques, F-91191 Gif-sur-Yvette (France); Pansu, Robert B. [Laboratoire de Photophysique et Photochimie Supramoléculaires et Macromoléculaires (CNRS UMR 8531), École Normale Supérieure de Cachan, 61 Avenue du Président Wilson, F-94235 Cachan cedex (France); Normand, Stéphane [CEA, LIST, Laboratoire Capteurs et Architectures Électroniques, F-91191 Gif-sur-Yvette (France)

    2014-06-01

    This work deals with the preparation and evaluation of plastic scintillators for neutron/gamma pulse shape discrimination (PSD). We succeeded in developing a plastic scintillator with good neutron/gamma discrimination properties in the range of what is already being commercialized. Several combinations of primary and secondary fluorophores were implemented in chemically modified polymers. These scintillators were fully characterized by fluorescence spectroscopy and under neutron irradiation. The materials proved to be stable for up to 5 years without any degradation of PSD properties. They were then classified in terms of their PSD capabilities and light yield. Our best candidate, 28.6 wt% of primary fluorophore with a small amount of secondary fluorophore, shows promising PSD results and is particularly suited to industrial development, because its preparation does not involve the use of expensive or exotic compounds. Furthermore, even at the highest prepared concentration, high stability over time was observed. As a proof of concept, one sample with dimensions 109 mm ∅×114 mm height (≈1 L) was prepared.

  16. Pulse-shape discrimination between electron and nuclear recoils in a NaI(Tl) crystal

    CERN Document Server

    Lee, H S; Adhikari, P; Choi, S; Hahn, I S; Jeon, E J; Joo, H W; Kang, W G; Kim, G B; Kim, H J; Kim, H O; Kim, K W; Kim, N Y; Kim, S K; Kim, Y D; Kim, Y H; Lee, J H; Lee, M H; Leonard, D S; Li, J; Oh, S Y; Olsen, S L; Park, H K; Park, H S; Park, K S; Shim, J H; So, J H

    2015-01-01

    We report on the response of a high light-output NaI(Tl) crystal to nuclear recoils induced by neutrons from an Am-Be source and compare the results with the response to electron recoils produced by Compton scattered 662 keV $\\gamma$-rays from a $^{137}$Cs source. The measured pulse-shape discrimination (PSD) power of the NaI(Tl) crystal is found to be significantly improved because of the high light output of the NaI(Tl) detector. We quantify the PSD power with a quality factor and estimate the sensitivity to the interaction rate for weakly interacting massive particles (WIMPs) with nucleons, and the result is compared with the annual modulation amplitude observed by the DAMA/LIBRA experiment. The sensitivity to spin-independent WIMP-nucleon interactions based on 100 kg$\\cdot$year of data from NaI detectors is estimated with simulated experiments, using the standard halo model.

  17. Pulse-shape discrimination with Cs2HfCl6 crystal scintillator

    Science.gov (United States)

    Cardenas, C.; Burger, A.; Goodwin, B.; Groza, M.; Laubenstein, M.; Nagorny, S.; Rowe, E.

    2017-10-01

    The results of investigation into cesium hafnium chloride (Cs2HfCl6) scintillating crystals as a promising detector to search for rare nuclear processes occurring in Hf isotopes is reported. The light output, quenching factor, and pulse-shape characteristics have been investigated at room temperature. The scintillation response of the crystal induced by α-particles and γ-quanta were studied to determine possibility of particle discrimination. Using the optimal filter method we obtained clear separation between signals with a factor of merit (FOM) = 9.3. This indicates that we are able to fully separate signals originating from α-particles and γ-quanta. Similar fruitful discrimination power was obtained by applying the mean time method (FOM = 7) and charge integration method (FOM = 7.5). The quenching factor for collimated 4 MeV α-particles is found to be 0.36, showing that α-particles generate more than a third of the light compared to γ-quanta at the same energy.

  18. Pulse-shape discrimination and energy resolution of a liquid-argon scintillator with xenon doping

    CERN Document Server

    Wahl, Christopher G; Lippincott, W Hugh; Nikkel, James A; Shin, Yunchang; McKinsey, Daniel N

    2014-01-01

    Liquid-argon scintillation detectors are used in fundamental physics experiments and are being considered for security applications. Previous studies have suggested that the addition of small amounts of xenon dopant improves performance in light or signal yield, energy resolution, and particle discrimination. In this study, we investigate the detector response for xenon dopant concentrations from 9 +/- 5 ppm to 1100 +/- 500 ppm xenon (by weight) in 6 steps. The 3.14-liter detector uses tetraphenyl butadiene (TPB) wavelength shifter with dual photomultiplier tubes and is operated in single-phase mode. Gamma-ray-interaction signal yield of 4.0 +/- 0.1 photoelectrons/keV improved to 5.0 +/- 0.1 photoelectrons/keV with dopant. Energy resolution at 662 keV improved from (4.4 +/- 0.2)% ({\\sigma}) to (3.5 +/- 0.2)% ({\\sigma}) with dopant. Pulse-shape discrimination performance degraded greatly at the first addition of dopant, slightly improved with additional additions, then rapidly improved near the end of our dopa...

  19. Pulse-shape discrimination techniques for the COBRA double beta-decay experiment at LNGS

    Science.gov (United States)

    Zatschler, S.; COBRA collaboration

    2017-09-01

    In modern elementary particle physics several questions arise from the fact that neutrino oscillation experiments have found neutrinos to be massive. Among them is the so far unknown nature of neutrinos: either they act as so-called Majorana particles, where one cannot distinguish between particle and antiparticle, or they are Dirac particles like all the other fermions in the Standard Model. The study of neutrinoless double beta-decay (0νββ-decay), where the lepton number conservation is violated by two units, could answer the question regarding the underlying nature of neutrinos and might also shed light on the mechanism responsible for the mass generation. So far there is no experimental evidence for the existence of 0νββ-decay, hence, existing experiments have to be improved and novel techniques should be explored. One of the next-generation experiments dedicated to the search for this ultra-rare decay is the COBRA experiment. This article gives an overview of techniques to identify and reject background based on pulse-shape discrimination.

  20. Broadband multilayer mirror and diffractive optics for attosecond pulse shaping in the 280-500 eV photon energy range

    Directory of Open Access Journals (Sweden)

    Schmidt J.

    2013-03-01

    Full Text Available Chirped broadband multilayer mirrors are key components to shape attosecond pulses in the XUV range. Compressing high harmonic pulses to their Fourier limit is the major goal for attosecond physics utilizing short pulse pump-probe experiments. Here, we report about the first implementation of multilayers and diffractive optics fulfilling these requirements in the “water-window” spectral range.

  1. Pulse

    Science.gov (United States)

    ... resting for at least 10 minutes. Take the exercise heart rate while you are exercising. ... pulse rate can help determine if the person's heart is pumping. Pulse ... rate gives information about your fitness level and health.

  2. Design and Applications of In-Cavity Pulse Shaping by Spectral Sculpturing in Mode-Locked Fibre Lasers

    Directory of Open Access Journals (Sweden)

    Sonia Boscolo

    2015-11-01

    Full Text Available We review our recent progress on the realisation of pulse shaping in passively-mode-locked fibre lasers by inclusion of an amplitude and/or phase spectral filter into the laser cavity. We numerically show that depending on the amplitude transfer function of the in-cavity filter, various regimes of advanced waveform generation can be achieved, including ones featuring parabolic-, flat-top- and triangular-profiled pulses. An application of this approach using a flat-top spectral filter is shown to achieve the direct generation of high-quality sinc-shaped optical Nyquist pulses with a widely tunable bandwidth from the laser oscillator. We also present the operation of an ultrafast fibre laser in which conventional soliton, dispersion-managed soliton (stretched-pulse and dissipative soliton mode-locking regimes can be selectively and reliably targeted by adaptively changing the dispersion profile and bandwidth programmed on an in-cavity programmable filter. The results demonstrate the strong potential of an in-cavity spectral pulse shaper for achieving a high degree of control over the dynamics and output of mode-locked fibre lasers.

  3. Discrete Fourier Transform Method for Discrimination of Digital Scintillation Pulses in Mixed Neutron-Gamma Fields

    CERN Document Server

    Safari, M J; Afarideh, H; Jamili, S; Bayat, E

    2016-01-01

    A Discrete Fourier Transform Method (DFTM) for discrimination between the signal of neutrons and gamma rays in organic scintillation detectors is presented. The method is based on the transformation of signals into the frequency domain using the sine and cosine Fourier transforms in combination with the discrete Fourier transform. The method is largely benefited from considerable differences that usually is available between the zero-frequency components of sine and cosine and the norm of the amplitude of the DFT for neutrons and gamma-ray signals. Moreover, working in frequency domain naturally results in considerable suppression of the unwanted effects of various noise sources that is expected to be effective in time domain methods. The proposed method could also be assumed as a generalized nonlinear weighting method that could result in a new class of pulse shape discrimination methods, beyond definition of the DFT. A comparison to the traditional Charge Integration Method (CIM), as well as the Frequency G...

  4. Investigation of Digital Sun Sensor Technology with an N-Shaped Slit Mask

    Directory of Open Access Journals (Sweden)

    Zheng You

    2011-10-01

    Full Text Available Nowadays sun sensors are being more widely used in satellites to determine the sunray orientation, thus development of a new version of sun sensor with lighter mass, lower power consumption and smaller size it of considerable interest. This paper introduces such a novel digital sun sensor, which is composed of a micro-electro-mechanical system (MEMS mask with an N-shaped slit as well as a single linear array charge-coupled device (CCD. The sun sensor can achieve the measurement of two-axis sunray angles according to the three sun spot images on the CCD formed by sun light illumination through the mask. Given the CCD glass layer, an iterative algorithm is established to correct the refraction error. Thus, system resolution, update rate and other characteristics are improved based on the model simulation and system design. The test of sun sensor prototype is carried out on a three-axis rotating platform with a sun simulator. The test results show that the field of view (FOV is ±60° × ±60° and the accuracy is 0.08 degrees of arc (3σ in the whole FOV. Since the power consumption of the prototype is only 300 mW and the update rate is 14 Hz, the novel digital sun sensor can be applied broadly in micro/nano-satellites, even pico-satellites.

  5. How Early Childhood Practitioners Build, Shape, and Construct Their Digital Practices: The Search for an Analytical Space

    Directory of Open Access Journals (Sweden)

    Tove Lafton

    2012-10-01

    Full Text Available This ongoing research examines how early childhood practitioners build, shape, and maintain digital practices through talk and action, assuming shared construction and development of knowledge. Based on empirical data I suggest looking beyond the social situated idea of knowledge building to include multiple elements, like individual knowledge, discourse and materiality, in analyses of the digital practice field in kindergarten. The discussions are both theoretically and empirically driven and tend to create a dynamic context model as a representation of the digital practice field.

  6. Pulse-Shape Analysis of Neutron-Induced Scintillation Light in Ni-doped 6LiF/ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Cowles, Christian C.; Behling, Richard S.; Imel, G. R.; Kouzes, Richard T.; Lintereur, Azaree; Robinson, Sean M.; Stave, Sean C.; Siciliano, Edward R.; Wang, Zheming

    2016-10-06

    Abstract–Alternatives to 3He are being investigated for gamma-ray insensitive neutron detection applications, including plutonium assay. One promising material is lithium-6 fluoride with silver activated zinc sulfide 6LiF/ZnS(Ag) in conjunction with a wavelength shifting plastic. Doping the 6LiF/ZnS(Ag) with nickel (Ni) has been proposed as a means of reducing the decay time of neutron signal pulses. This research performed a pulse shape comparison between Ni-doped and non-doped 6LiF/ZnS(Ag) neutron pulses. The Ni-doped 6LiF/ZnS(Ag) had a 32.7% ± 0.3 increase in neutron pulse height and a 32.4% ± 0.3 decrease in neutron pulse time compared to the non-doped 6LiF/ZnS(Ag). Doping 6LiF/ZnS(Ag) with nickel may allow neutron detector operation with improved signal to noise ratios, and reduced pulse pileup affects, increasing the accuracy and range of source activities with which such a detector could operate.

  7. In-Fiber Subpicosecond Pulse Shaping for Nonlinear Optical Telecommunication Data Processing at 640 Gbit/s

    Directory of Open Access Journals (Sweden)

    J. Azaña

    2012-01-01

    Full Text Available We review recent work on all-fiber (long-period fiber grating devices for optical pulse shaping, particularly flat-top pulse generation, down to the subpicosecond range and their application for nonlinear switching (demultiplexing of optical time-division multiplexed (OTDM data signals in fiber-optic telecommunication links operating up to 640 Gbit/s. Experiments are presented demonstrating error-free 640-to-10 Gbit/s demultiplexing of the 64 tributary channels using the generated flat-top pulses for temporal gating in a Kerr-effect-based nonlinear optical loop mirror. The use of flat-top pulses has critical benefits in the demultiplexing process, including a significantly increased timing-jitter tolerance (up to ~500 fs, i.e., 30% of the bit period and the associated improvement in the bit-error-rate performance (e.g., with a sensitivity increase of up to ~13 dB as compared with the use of Gaussian-like gating pulses. Long-period fiber grating pulse shapers with reduced polarization dependence are fabricated and successfully used for polarization-independent 640-to-10 Gbit/s demultiplexing experiments.

  8. Organic scintillators with pulse shape discrimination for detection of radiation (Conference Presentation)

    Science.gov (United States)

    Mabe, Andrew; Carman, M. Leslie; Glenn, Andrew M.; Zaitseva, Natalia P.; Payne, Stephen A.

    2016-09-01

    The detection of neutrons in the presence of gamma-ray fields has important applications in the fields of nuclear physics, homeland security, and medical imaging. Organic scintillators provide several attractive qualities as neutron detection materials including low cost, fast response times, ease of scaling, and the ability to implement pulse shape discrimination (PSD) to discriminate between neutrons and gamma-rays. This talk will focus on amorphous organic scintillators both in plastic form and small-molecule organic glass form. The first section of this talk will describe recent advances and improvements in the performance of PSD-capable plastic scintillators. The primary advances described in regard to modification of the polymer matrix, evaluation of new scintillating dyes, improved fabrication conditions, and implementation of additives which impart superior performance and mechanical properties to PSD-capable plastics as compared to commercially-available plastics and performance comparable to PSD-capable liquids. The second section of this talk will focus on a class of small-molecule organic scintillators based on modified indoles and oligophenylenes which form amorphous glasses as PSD-capable neutron scintillation materials. Though indoles and oligophenylenes have been known for many decades, their PSD properties have not been investigated and their scintillation properties only scantily investigated. Well-developed synthetic methodologies have permitted the synthesis of a library of structural analogs of these compounds as well as the investigation of their scintillation properties. The emission wavelengths of many indoles are in the sensitive region of common photomultiplier tubes, making them appropriate to be used as scintillators in either pure or doped form. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This work has been supported by the U

  9. Liquid mixing enhanced by pulse width modulation in a Y-shaped jet configuration

    Science.gov (United States)

    Xia, Qingfeng; Zhong, Shan

    2013-04-01

    In this paper, mixing between two fluid streams, which are injected into a planar mixing channel via a Y-shaped confluence section at the same volume flow rate, is studied experimentally. The injection of the two fluid streams is controlled by two separate solenoid valves, which are operated with a phase difference of 180°, using pulse width modulation. The experiments are conducted using water at a mean Reynolds number between 83 and 250, a range of pulsation frequencies and two duty cycles (25 and 50%). Both particle-image velocimetry and planar laser-induced fluorescence technique are used to visualize the flow patterns and to quantify the mixing degree in the mixing channel. This experiment shows that the pulsation of each jet produces vortical structures, which promotes mixing via vortex entrainment and vortex breakup, and at the same time the mixing is also greatly enhanced by sequential segmentation produced by a 180° out-of-phase pulsation of the two jets. This mixing enhancement method is effective at a Reynolds number greater than 125 with a mixing degree of 0.9 being achieved. For the Reynolds numbers studied in the present experiments, an optimal frequency exists, which corresponds to a Strouhal number in the range of 0.5-2. Furthermore, at a given mean Reynolds number a lower duty cycle is found to produce a better mixing due to the resultant higher instantaneous Reynolds number in the jet flow. It is also found that pulsation of only one jet can produce a similar mixing effect.

  10. Scintillation-only based pulse shape discrimination for nuclear and electron recoils in liquid xenon

    Energy Technology Data Exchange (ETDEWEB)

    Ueshima, K., E-mail: ueshima@suketto.icrr.u-tokyo.ac.jp [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan); Abe, K.; Hiraide, K.; Hirano, S. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan); Kishimoto, Y. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan); Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Kobayashi, K.; Koshio, Y. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan); Liu, J.; Martens, K. [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Moriyama, S.; Nakahata, M. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan); Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Nishiie, H.; Ogawa, H.; Sekiya, H.; Shinozaki, A. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan); Suzuki, Y. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan); Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Takeda, A. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan); Yamashita, M. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan); Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); and others

    2011-12-11

    In a dedicated test setup at the Kamioka Observatory we studied pulse shape discrimination (PSD) in liquid xenon (LXe) for dark matter searches in the absence of an externally applied electric field. PSD in LXe was based on the observation that scintillation light from electron events was emitted over a longer period of time than that of nuclear recoil events, and our method used a simple ratio of early to total scintillation light emission in a single scintillation event. Requiring an efficiency of 50% for nuclear recoil retention we reduced the electron background by a factor of 7.7{+-}1.1(stat){+-}{sub 0.6}{sup 1.2}(sys) Multiplication-Sign 10{sup -2} at energies between 4.8 and 7.2 keV{sub ee} and 7.7{+-}2.8(stat){+-}{sub 2.8}{sup 2.5}(sys) Multiplication-Sign 10{sup -3} at energies between 9.6 and 12 keV{sub ee} for a scintillation light yield of 20.9 photoelectrons/keV{sub ee}. Further study was done by masking some of that light to reduce this yield to 4.6 photoelectrons/keV{sub ee}. Under these conditions the same method results in an electron event reduction by a factor of 2.4{+-}0.2(stat){+-}{sub 0.2}{sup 0.3}(sys) Multiplication-Sign 10{sup -1} for the lower of the energy regions above. We also observe that in contrast to nuclear recoils the fluctuations in our early to total ratio for electron events are larger than expected from statistical fluctuations.

  11. The role of pulse shape in motor cortex transcranial magnetic stimulation using full-sine stimuli

    DEFF Research Database (Denmark)

    Delvendahl, Igor; Gattinger, Norbert; Berger, Thomas;

    2014-01-01

    excitation. Preferential excitation of neuronal target cells in the posterior-anterior segment or targeting of different neuronal structures by the two half-segments can explain this result. Thus, our findings help understanding the mechanisms of neural stimulation by full-sine TMS.......A full-sine (biphasic) pulse waveform is most commonly used for repetitive transcranial magnetic stimulation (TMS), but little is known about how variations in duration or amplitude of distinct pulse segments influence the effectiveness of a single TMS pulse to elicit a corticomotor response. Using......) compared monophasic, half-sine, and full-sine pulses, (ii) applied two-segment pulses consisting of two identical half-sines, and (iii) manipulated amplitude, duration, and current direction of the first or second full-sine pulse half-segments. RMT was significantly higher using half-sine or monophasic...

  12. Novel D-shaped fiber fabrication method for saturable absorber application in the generation of ultra-short pulses

    Science.gov (United States)

    Ahmad, H.; Safaei, R.; Rezayi, M.; Amiri, I. S.

    2017-08-01

    A cost-efficient, time-saving and effective technique for the fabrication of D-shaped fibers is presented, to provide a platform with a strong evanescent field to be used as a saturable absorber (SA). This technique provides flexibility by removing the required portion of the fiber, and a small polished length which offers a unique opportunity to deposit SA on its surface by simply submerging it in the SA solution without high losses. A compact fiber laser utilizing a graphene oxide coating on a fabricated D-shaped fiber as an SA capable of generating ultrashort pulses is designed and verified. We report the generation of ultrafast pulses as short as 227 fs with a 34.7 MHz repetition rate, having a 3 dB bandwidth of 14 nm at the 1570 nm center wavelength.

  13. Simulation of picosecond pulse propagation in fibre-based radiation shaping units

    Science.gov (United States)

    Kuptsov, G. V.; Petrov, V. V.; Laptev, A. V.; Petrov, V. A.; Pestryakov, E. V.

    2016-09-01

    We have performed a numerical simulation of picosecond pulse propagation in a combined stretcher consisting of a segment of a telecommunication fibre and diffraction holographic gratings. The process of supercontinuum generation in a nonlinear photoniccrystal fibre pumped by picosecond pulses is simulated by solving numerically the generalised nonlinear Schrödinger equation; spectral and temporal pulse parameters are determined. Experimental data are in good agreement with simulation results. The obtained results are used to design a high-power femtosecond laser system with a pulse repetition rate of 1 kHz.

  14. Pulse shape discrimination between (fast or thermal) neutrons and gamma rays with plastic scintillators: State of the art

    Energy Technology Data Exchange (ETDEWEB)

    Bertrand, Guillaume H.V. [CEA, LIST, Laboratoire Capteurs & Architectures Électroniques, CEA Saclay, F-91191 Gif-sur-Yvette cedex (France); Hamel, Matthieu, E-mail: matthieu.hamel@cea.fr [CEA, LIST, Laboratoire Capteurs & Architectures Électroniques, CEA Saclay, F-91191 Gif-sur-Yvette cedex (France); Normand, Stéphane [CEA, DAM, Le Ponant, 25 rue Leblanc, F-75015 Paris (France); Sguerra, Fabien [CEA, LIST, Laboratoire Capteurs & Architectures Électroniques, CEA Saclay, F-91191 Gif-sur-Yvette cedex (France)

    2015-03-11

    We would like to present here with the eyes of the chemist the most recent developments of plastic scintillators (PS) for neutron detection. This review covers the period from 2000 to August 2014, and is fragmented in two main chapters. The first chapter deals with the chemical modifications for thermal neutron capture, whereas the second chapter presents the various strategies used to enhance the response to fast neutrons via pulse shape discrimination. For each chapter the theory is also explained.

  15. Long-Term Time Variability in the X-Ray Pulse Shape of the Crab Nebula Pulsar

    Science.gov (United States)

    Fazio, Giovanni G.

    2000-01-01

    This is the final performance report for our grant 'Long-Term Time Variability in the X-Ray Pulse Shape of the Crab Nebula Pulsar.' In the first year of this grant, we received the 50,000-second ROSAT (German acronym for X-ray satellite) High Resolution Images (HRI) observation of the Crab Nebula pulsar. We used the data to create a 65-ms-resolution pulse profile and compared it to a similar pulse profile obtained in 1991. No statistically significant differences were found. These results were presented at the January 1998 meeting of the American Astronomical Society. Since then, we have performed more sensitive analyses to search for potential changes in the pulse profile shape between the two data sets. Again, no significant variability was found. In order to augment this long (six-year) baseline data set, we have analyzed archival observations of the Crab Nebula pulsar with the Rossi X-Ray Timing Explorer (RXTE). While these observations have shorter time baselines than the ROSAT data set, their higher signal-to-noise offers similar sensitivity to long-term variability. Again, no significant variations have been found, confirming our ROSAT results. This work was done in collaboration with Prof. Stephen Eikenberry, Cornell University. These analyses will be included in Cornell University graduate student Dae-Sik Moon's doctoral thesis.

  16. An algorithm for charge-integration, pulse-shape discrimination and estimation of neutron/photon misclassification in organic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Polack, J.K., E-mail: kpolack@umich.edu [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Flaska, M. [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Enqvist, A. [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611 (United States); Sosa, C.S.; Lawrence, C.C.; Pozzi, S.A. [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)

    2015-09-21

    Organic scintillators are frequently used for measurements that require sensitivity to both photons and fast neutrons because of their pulse shape discrimination capabilities. In these measurement scenarios, particle identification is commonly handled using the charge-integration pulse shape discrimination method. This method works particularly well for high-energy depositions, but is prone to misclassification for relatively low-energy depositions. A novel algorithm has been developed for automatically performing charge-integration pulse shape discrimination in a consistent and repeatable manner. The algorithm is able to estimate the photon and neutron misclassification corresponding to the calculated discrimination parameters, and is capable of doing so using only the information measured by a single organic scintillator. This paper describes the algorithm and assesses its performance by comparing algorithm-estimated misclassification to values computed via a more traditional time-of-flight estimation. A single data set was processed using four different low-energy thresholds: 40, 60, 90, and 120 keVee. Overall, the results compared well between the two methods; in most cases, the algorithm-estimated values fell within the uncertainties of the TOF-estimated values.

  17. The role of pulse shape in motor cortex transcranial magnetic stimulation using full-sine stimuli.

    Directory of Open Access Journals (Sweden)

    Igor Delvendahl

    Full Text Available A full-sine (biphasic pulse waveform is most commonly used for repetitive transcranial magnetic stimulation (TMS, but little is known about how variations in duration or amplitude of distinct pulse segments influence the effectiveness of a single TMS pulse to elicit a corticomotor response. Using a novel TMS device, we systematically varied the configuration of full-sine pulses to assess the impact of configuration changes on resting motor threshold (RMT as measure of stimulation effectiveness with single-pulse TMS of the non-dominant motor hand area (M1. In young healthy volunteers, we (i compared monophasic, half-sine, and full-sine pulses, (ii applied two-segment pulses consisting of two identical half-sines, and (iii manipulated amplitude, duration, and current direction of the first or second full-sine pulse half-segments. RMT was significantly higher using half-sine or monophasic pulses compared with full-sine. Pulses combining two half-sines of identical polarity and duration were also characterized by higher RMT than full-sine stimuli resulting. For full-sine stimuli, decreasing the amplitude of the half-segment inducing posterior-anterior oriented current in M1 resulted in considerably higher RMT, whereas varying the amplitude of the half-segment inducing anterior-posterior current had a smaller effect. These findings provide direct experimental evidence that the pulse segment inducing a posterior-anterior directed current in M1 contributes most to corticospinal pathway excitation. Preferential excitation of neuronal target cells in the posterior-anterior segment or targeting of different neuronal structures by the two half-segments can explain this result. Thus, our findings help understanding the mechanisms of neural stimulation by full-sine TMS.

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

    Energy Technology Data Exchange (ETDEWEB)

    Fuente, R. de la [University of Leon, Escuela de Ingenieria Industrial, Leon 24071 (Spain); Celis, B. de [University of Leon, Escuela de Ingenieria Industrial, Leon 24071 (Spain)], E-mail: bcelc@unileon.es; Canto, V. del; Lumbreras, J.M. [University of Leon, Escuela de Ingenieria Industrial, Leon 24071 (Spain); Celis, Alonso B. de [King' s College London, IoP, De Crespigny Park, SE58AF (United Kingdom); Martin-Martin, A. [Laboratorio LIBRA, Edificio I-D, Paseo Belen 3. 47011 Valladolid (Spain); Departamento de Fisica Teorica, Atomica y Optica, Facultad de Ciencias. Po Prado de la Magdalena, s/n. 47005 Valladolid (Spain)], E-mail: alonsomm@libra.uva.es; Gutierrez-Villanueva, J.L. [Laboratorio LIBRA, Edificio I-D, Paseo Belen 3. 47011 Valladolid (Spain); Departamento de Fisica Teorica, Atomica y Optica, Facultad de Ciencias. Po Prado de la Magdalena, s/n. 47005 Valladolid (Spain)], E-mail: joselg@libra.uva.es

    2008-10-15

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

  19. Noise-immunity processing of digital multilevel pulse-amplitude modulation signals

    Directory of Open Access Journals (Sweden)

    A. S. Makarenko

    2015-12-01

    Full Text Available Introduction. The main properties and features of spectral-effective multi-level pulse amplitude modulation digital signals at coherent reception are presented. It is shown that the phase locked loop circuit (PLL circuit used in the receiver is able to work at SNR > 5 dB.Object of the paper. We propose a new scheme of noise compensator at an intermediate frequency, allowing us to obtain increasing of SNR on 15–25 dB when error of PLL is equal zero. The noise compensator has the gain 8–18 dB at error of PLL = 33° that is able to work at SNR = 5 dB. As result, we can obtain a required SNR for determined BER in systems with multi-level PAM.Conclusions. This technical solution makes a spectrally-efficient system using multi-level amplitude modulation is also energy efficient, forward-looking and competitive. The power transmitters of cell phones and radio relay lines of mobile communication systems can be reduced by 10 times or at the same transmitter power improvement the quality of communication or range is presented.

  20. On-line surveillance of a dynamic process by a moving system based on pulsed digital holographic interferometry.

    Science.gov (United States)

    Pedrini, Giancarlo; Alexeenko, Igor; Osten, Wolfgang; Schnars, Ulf

    2006-02-10

    A method based on pulsed digital holographic interferometry for the measurement of dynamic deformations of a surface by using a moving system is presented. The measuring system may move with a speed of several meters per minute and can measure deformation of the surface with an accuracy of better than 50 nm. The deformation is obtained by comparison of the wavefronts recorded at different times with different laser pulses produced by a Nd:YAG laser. The effect due to the movement of the measuring system is compensated for by digital processing of the different holograms. The system is well suited for on-line surveillance of a dynamic process such as laser welding and friction stir welding. Experimental results are presented, and the advantages of the method are discussed.

  1. Femtosecond pulse shaping by modulating the refractive index modulation of volume holographic grating.

    Science.gov (United States)

    Yan, Xiaona; Dai, Ye; Gao, Zixuan; Chen, Yuanyuan; Yang, Xihua; Ma, Guohong

    2013-03-25

    Based on the modified Kogelnik's coupled-wave theory, time- and frequency-domain diffractions of a femtosecond pulse from transmitted volume holographic gratings (VHGs) are theoretically studied. Results show that when the refractive index modulation of the VHG changes in a certain range, the number of temporal diffracted pulse will evolve from one to two, then to three, and this pulse number evolution is periodic. This particular phenomenon can be explained by diffraction intensity spectrum and the overmodulation effect of refractive index modulation of transmitted VHG. Moreover, we find centers of all temporal diffracted pulses translate along the negative time axis, and the translation is irrelevant to the refractive index modulations. We will use time delay of volume grating to give a reasonable explanation.

  2. The Use Of A Digital Store To Provide Pulsed Fluoroscopy And Stored Images During Gastro-Intestinal Examinations

    Science.gov (United States)

    Hynes, D. M.; Edmonds, E. W.; Rowlands, J. A.; Pack, W. W.

    1984-08-01

    A 512 X 512 digital store has replaced a video disc as a storage mechanism during pulsed fluoroscopy. This system, storing 1 TV field from a 1023 line signal following each pulse, is much more stable than the analog disc and can also reduce the fluoroscopic dose by 75%. This stability now makes the concept of pulsed fluoroscopy acceptable from the clinical point of view. Furthermore, the stored images on this matrix can resolve to 1.5 line pairs per mm, which produces useful permanent hard copy. This represents a further extension of clinical videofluorography, already developed by the authors. Its implementation for storage of gastro-intestinal examinations will be discussed, with assessment of the relationship of x-ray dose to image quality.

  3. Nyquist WDM superchannel using offset-16QAM and receiver-side digital spectral shaping.

    Science.gov (United States)

    Xiang, Meng; Fu, Songnian; Tang, Ming; Tang, Haoyuan; Shum, Perry; Liu, Deming

    2014-07-14

    The performance of Nyquist WDM superchannel using advanced modulation formats with coherent detection is degraded due to the existence of both inter-symbol interference (ISI) and inter-channel interference (ICI). Here, we propose and numerically investigate a Nyquist WDM superchannel using offset-16QAM and receiver-side digital spectral shaping (RS-DSS), achieving a spectral efficiency up to 7.44 bit/s/Hz with 7% hard-decision forward error correction (HD-FEC) overhead. Compared with Nyquist WDM superchannel using 16QAM and RS-DSS, the proposed system has 1.4 dB improvement of required OSNR at BER = 10(-3) in the case of back-to-back (B2B) transmission. Furthermore, the range of launched optical power allowed beyond HD-FEC threshold is drastically increased from -6 dBm to 1.2 dBm, after 960 km SSMF transmission with EDFA-only. In particular, no more than 1.8 dB required OSNR penalty at BER = 10(-3) is achieved for the proposed system even with the phase difference between channels varying from 0 to 360 degree.

  4. Adaptive digital fringe projection technique for high dynamic range three-dimensional shape measurement.

    Science.gov (United States)

    Lin, Hui; Gao, Jian; Mei, Qing; He, Yunbo; Liu, Junxiu; Wang, Xingjin

    2016-04-04

    It is a challenge for any optical method to measure objects with a large range of reflectivity variation across the surface. Image saturation results in incorrect intensities in captured fringe pattern images, leading to phase and measurement errors. This paper presents a new adaptive digital fringe projection technique which avoids image saturation and has a high signal to noise ratio (SNR) in the three-dimensional (3-D) shape measurement of objects that has a large range of reflectivity variation across the surface. Compared to previous high dynamic range 3-D scan methods using many exposures and fringe pattern projections, which consumes a lot of time, the proposed technique uses only two preliminary steps of fringe pattern projection and image capture to generate the adapted fringe patterns, by adaptively adjusting the pixel-wise intensity of the projected fringe patterns based on the saturated pixels in the captured images of the surface being measured. For the bright regions due to high surface reflectivity and high illumination by the ambient light and surfaces interreflections, the projected intensity is reduced just to be low enough to avoid image saturation. Simultaneously, the maximum intensity of 255 is used for those dark regions with low surface reflectivity to maintain high SNR. Our experiments demonstrate that the proposed technique can achieve higher 3-D measurement accuracy across a surface with a large range of reflectivity variation.

  5. Separating Morphologically Similar Pollen Types Using Basic Shape Features from Digital Images: A Preliminary Study

    Directory of Open Access Journals (Sweden)

    Katherine A. Holt

    2014-08-01

    Full Text Available Premise of the study: One of the many advantages offered by automated palynology systems is the ability to vastly increase the number of observations made on a particular sample or samples. This is of particular benefit when attempting to fully quantify the degree of variation within or between closely related pollen types. Methods: An automated palynology system (Classifynder has been used to further investigate the variation in pollen morphology between two New Zealand species of Myrtaceae (Leptospermum scoparium and Kunzea ericoides that are of significance in the New Zealand honey industry. Seven geometric features extracted from automatically gathered digital images were used to characterize the range of shape and size of the two taxa, and to examine the extent of previously reported overlap in these variables. Results: Our results indicate a degree of overlap in all cases. The narrowest overlap was in measurements of maximum Feret diameter (MFD in grains oriented in polar view. Multivariate statistical analysis using all seven factors provided the most robust discrimination between the two types. Discussion: Further work is required before this approach could be routinely applied to separating the two pollen types used in this study, most notably the development of comprehensive reference distributions for the types in question.

  6. Advanced digital optical communications

    CERN Document Server

    Binh, Le Nguyen

    2015-01-01

    This book provides a fundamental understanding of digital communication applications in optical communication technologies. Emphasizing operation principles versus mathematical analysis, the Second Edition includes new coverage of superchannel optical transmission systems, metropolitan and long-haul optical systems and networks, and Nyquist pulse shaping and high spectral efficiency of optical transmission systems, as well as new homework problems and examples. Featuring theoretical foundations as well as practical case studies, the text focuses on enhancements to digital technologies that are

  7. Shaping frequency correlations of ultrafast pulse-pumped modulational instability in gas-filled hollow-core PCF

    CERN Document Server

    Finger, Martin A; Russell, Philip St J; Chekhova, Maria V

    2016-01-01

    We vary the time-frequency mode structure of ultrafast pulse-pumped modulational instability (MI) in an argon-filled hollow-core kagom\\'e-style PCF by adjusting the pressure, pump pulse chirp, fiber length and parametric gain. Compared to solid-core systems, the pressure dependent dispersion landscape brings increased flexibility to the tailoring of frequency correlations. The resulting mode content is characterized by measuring the multimode second-order correlation function g(2) and by directly observing frequency correlations in single-shot MI spectra. We show that, from such measurements, the shapes and weights of time-frequency Schmidt (TFS) modes can be extracted and that the number of modes directly influences the shot-to-shot pulse-energy and spectral-shape fluctuations in MI. Using this approach we are able to change the number of TFS modes from 1.3 (g(2) = 1.75) to 4 (g(2) = 1.25) using only a single fiber.

  8. 低强度脉冲中子束的数字式n/γ分辨测量%Digital n/γ discrimination measurement of low intensity pulsed neutron

    Institute of Scientific and Technical Information of China (English)

    田耕; 欧阳晓平; 渠红光; 张显鹏; 刘金良; 李海涛

    2015-01-01

    Background: The traditional measurement methods in which the detectors are working in counting mode or current mode all have limitations in the measurement of low intensity pulsed neutron.Purpose: We aim to establish a method for low intensity pulsed neutron measurement to acquire the spectra of energy and time by digitalizing and analyzing the fast current pulse generated by detector as each single neutron induced.Methods: A digital pulse shape discrimination (DPSD) system for low intensity pulsed neutron measurement has been developed, which employs wideband digital oscilloscope as data acquisition device. With BC501A liquid scintillator detector, the system can acquire and store the waveforms of neutrons andγ-rays, and discriminate neutrons from all waveforms by DPSD algorithms. The system has two operation modes as “continuous acquisition” and “acquisition window with time stamp” for different event rates according to the intensity of pulsed neutron.Results: The function of pulse height analysis of neutrons is achieved, and time information of neutron’s arriving can be acquired by the analysis of the position of the waveform in the record or the time stamps. Experiment has been carried out with Am-Be neutron source with the operation mode of acquisition window, and the neutron pulse height spectrum, time spectrum and n/γ discrimination spectrum have been acquired.Conclusion: The spectra of energy and time of low intensity pulsed neutron can be measured by the digital method which employees wideband digital oscilloscope and digital signal processing algorithms, and has the advantage that all original waveforms of neutrons andγ-rays can be stored for further analysis.%针对低强度脉冲中子束测量,使用高速数字示波器作为数据采集设备,配合BC501A液体闪烁体探测器组建了数字式脉冲形状甄别(Digital Pulse Shape Discrimination, DPSD)测量系统,实现了中子的n/γ分辨测量。系统工作时采集并存

  9. Hybridization of phase retrieval and off-axis digital holography for high resolution imaging of complex shape objects

    Science.gov (United States)

    Wang, Fengpeng; Wang, Dayong; Rong, Lu; Wang, Yunxin; Zhao, Jie

    2017-05-01

    In this paper, a hybrid method of phase retrieval and off-axis digital holography is proposed for imaging of the complex shape objects. Off-axis digital hologram and in-line hologram are recorded. The approximate phase distributions in the recording plane and object plane are obtained by constrained optimization approach from the off-axis hologram, and they are used as the initial value and the constraints in the phase retrieval for eliminating the twin image of in-line holography. Numerical simulations and optical experiments were carried out to validate the proposed method.

  10. Phase-only shaped laser pulses in optimal control theory: Application to indirect photofragmentation dynamics in the weak-field limit

    DEFF Research Database (Denmark)

    Shu, Chuan-Cun; Henriksen, Niels E.

    2012-01-01

    We implement phase-only shaped laser pulses within quantum optimal control theory for laser-molecule interaction. This approach is applied to the indirect photofragmentation dynamics of NaI in the weak-field limit. It is shown that optimized phase-modulated pulses with a fixed frequency...

  11. Digital tachometer

    Science.gov (United States)

    Shirokov, B.

    1984-03-01

    A tachometer with digital indication was built for measuring the speed of automobile engines with only two digits in the rpm readout. It consists of a Schmitt trigger for shaping input pulses, a pulse counter, a cycle time setting multivibrator and a readout time setting multivibrator, a stabilizer, a flicker suppressor, and a capacitive transducer. The instrument operates from a 12 V battery and draws 180 mA. The transducer includes a 30 to 50 turns coil of PEL 0.5 wire wound around the conductor which connects the ignition coil to the engine distributor and its transistor is mounted on a fin-type heat sink. Tuneup of the tachometer involves matching the transducer capacitor for maximum voltage at minimum current and trimming the readout time setting multivibrator with its adjustable resistor for a 1.5 readout with a 50 Hz input signal.

  12. The influence of the excitation pulse shape on the stress wave propagation in a bcc iron crystal

    Directory of Open Access Journals (Sweden)

    Červená O.

    2008-12-01

    Full Text Available This article presents a large-scale molecular dynamic simulations of wave propagation in a cracked bcc (body centered cubic iron crystal based on an N-body potential model which gives a good description of an anisotropic elasticity. The crystal is loaded by a stress pulse on its front face and the response is detected on its opposite face. The various shapes, amplitudes, and widths of stress pulse are considered. The simulations are performed also for a central pre-existing Griffith crack. The crack is embedded in a bcc iron crystal having a basic cubic orientation. The acquired results bring important information for further analysis oriented to new NDT nanoscale methods.

  13. Modeling digital pulse waveforms by solving one-dimensional Navier-stokes equations.

    Science.gov (United States)

    Fedotov, Aleksandr A; Akulova, Anna S; Akulov, Sergey A

    2016-08-01

    Mathematical modeling for composition distal arterial pulse wave in the blood vessels of the upper limbs was considered. Formation of distal arterial pulse wave is represented as a composition of forward and reflected pulse waves propagating along the arterial vessels. The formal analogy between pulse waves propagation along the human arterial system and the propagation of electrical oscillations in electrical transmission lines with distributed parameters was proposed. Dependencies of pulse wave propagation along the human arterial system were obtained by solving the one-dimensional Navier-Stokes equations for a few special cases.

  14. Study of an indirect-drive ignition capsule with the main pulse shape of decompression and recompression

    Science.gov (United States)

    Ye, Wenhua; Wang, Lifeng; Wu, Junfeng; Huo, Wenyi; Lan, Ke; Liu, Jie; He, Xian Tu

    2015-11-01

    Hydrodynamics in the low-foot (LF) implosion during the National Ignition Campaign is highly nonlinearity, which results in significant amount of CH(Si) ablator material mixing into the hot spot and low-mode non-uniformity of the shell areal density. The high-foot (HF) implosion after the NIC largely suppresses mediate- and high- mode hydrodynamic instabilities, in which neutron yields go up an order of magnitude compared to the LF implosion, but the hot spot pressure is still low and the hot spot shape goes bad when the peak power is increased for larger implosion velocity. In our new ignition capsule design, first, the HF prepulse similar to the HF implosion on NIF is adopted for resisting the CH(Si) ablator mix problem; second, the new main pulse shape of decompression and recompression (DR) is proposed to improve performance of the HF implosion on NIF. In this scheme of the DR, the secondary auxiliary shock (SAS) is produced during the late of the main pulse by the recompression pulse to raise the shell density for improving the hot spot pressure. The decompression pulse is used for reducing ablative pressure in order to relax the limit of the peak drive power for SAS production. The SAS colliding with the rebound shock from the center also improves the hot spot pressure and temperature, which is very useful to stabilize the hydrodynamic instabilities during the deceleration stage of implosion for the hot spot ignition. Decompressing the outer part of the ablator thickens the shell to lessen feed-through of perturbations from the ablative to inner interfaces. In this presentation, good 1D and 2D performance of implosion of the DR scheme is reported, especially reduced growth of perturbations at the interface between the hot spot and the main DT fuel.

  15. Modeling the pulse shape of Q-switched lasers to account for terminal-level relaxation

    Institute of Scientific and Technical Information of China (English)

    Zeng Qin-Yong; Wan Yong; Xiong Ji-Chuan; Zhu Da-Yong

    2011-01-01

    To account for the effect of lower-level relaxation, we have derived a characteristic equation for describing the laser pulse from the modified rate equations for Q-switched lasers. The pulse temporal profile is related to the ratio of the lower-level lifetime to the cavity lifetime and the number of times the population inversion density is above the threshold. By solving the coupled rate equations numerically, the effect of terminal-level lifetime on pulse temporal behaviour is analysed. The mode is applied to the case of a diode-pumped Nd:YAG laser that is passively Q-switched by a Cr4+:YAG absorber. Theoretical results show good agreement with the experiments.

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

    Science.gov (United States)

    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.

  17. Light Collection and Pulse-Shape Discrimination in Elongated Scintillator Cells for the PROSPECT Reactor Antineutrino Experiment

    CERN Document Server

    Ashenfelter, J; Band, H R; Barclay, G; Bass, C D; Berish, D; Bowden, N S; Bowes, A; Brodsky, J P; Bryan, C D; Cherwinka, J J; Chu, R; Classen, T; Commeford, K; Davee, D; Dean, D; Deichert, G; Diwan, M V; Dolinski, M J; Dolph, J; Dwyer, D A; Gaison, J K; Galindo-Uribarri, A; Gilje, K; Glenn, A; Goddard, B W; Green, M; Han, K; Hans, S; Heeger, K M; Heffron, B; Jaffe, D E; Langford, T J; Littlejohn, B R; Caicedo, D A Martinez; McKeown, R D; Mendenhall, M P; Mueller, P; Mumm, H P; Napolitano, J; Neilson, R; Norcini, D; Pushin, D; Qian, X; Romero, E; Rosero, R; Saldana, L; Seilhan, B S; Sharma, R; Sheets, S; Stemen, N T; Surukuchi, P T; Varner, R L; Viren, B; Wang, W; White, B; White, C; Wilhelmi, J; Williams, C; Wise, T; Yao, H; Yeh, M; Yen, Y -R; Zangakis, G; Zhang, C; Zhang, X

    2015-01-01

    A meter-long, 23-liter EJ-309 liquid scintillator detector has been constructed to study the light collection and pulse-shape discrimination performance of elongated scintillator cells for the PROSPECT reactor antineutrino experiment. The magnitude and uniformity of light collection and neutron/gamma discrimination power in the energy range of antineutrino inverse beta decay products have been studied using gamma and spontaneous fission calibration sources deployed along the cell long axis. We also study neutron-gamma discrimination and light collection abilities for differing PMT and reflector configurations. Key design features for optimizing MeV-scale response and background rejection capabilities are identified.

  18. Cooling molecular vibrations with shaped laser pulses: Optimal control theory exploiting the timescale separation between coherent excitation and spontaneous emission

    CERN Document Server

    Reich, Daniel M

    2013-01-01

    Laser cooling of molecules employing broadband optical pumping involves a timescale separation between laser excitation and spontaneous emission. Here, we optimize the optical pumping step using shaped laser pulses. We derive two optimization functionals to drive population into those excited state levels that have the largest spontaneous emission rates to the target state. We show that, when using optimal control, laser cooling of molecules works even if the Franck-Condon map governing the transitions is preferential to heating rather than cooling. Our optimization functional is also applicable to the laser cooling of other degrees of freedom provided the cooling cycle consists of coherent excitation and dissipative deexcitation steps whose timescales are separated.

  19. Single-shot three-dimensional shape measurement by low-coherent optical path difference digital holography.

    Science.gov (United States)

    Tanaka, Yuji; Mori, Yutaka; Nomura, Takanori

    2014-09-20

    A single-shot three-dimensional (3D) shape measurement by low-coherent optical path difference digital holography with small energy consumption is proposed. The use of a superluminescent diode makes it possible. Weighting of the single hologram and numerical reconstruction give the 3D shape of an object. Experimental results using a simple object (the surface of a button cell battery) are given. By comparison with experimental results using a vertical scanning method, the proposed method is confirmed. The effects of a shift interval of the hologram and a zero-order component on a measurement result are also discussed.

  20. Influence of crystal-orientation effects on pulse-shape-based identification of heavy-ions stopped in silicon detectors

    Science.gov (United States)

    Bardelli, L.; Bini, M.; Casini, G.; Pasquali, G.; Poggi, G.; Barlini, S.; Becla, A.; Berjillos, R.; Borderie, B.; Bougault, R.; Bruno, M.; Cinausero, M.; D'Agostino, M.; de Sanctis, J.; Dueñas, J. A.; Edelbruck, P.; Geraci, E.; Gramegna, F.; Kordyasz, A.; Kozik, T.; Kravchuk, V. L.; Lavergne, L.; Marini, P.; Nannini, A.; Negoita, F.; Olmi, A.; Ordine, A.; Piantelli, S.; Rauly, E.; Rivet, M. F.; Rosato, E.; Scian, C.; Stefanini, A. A.; Vannini, G.; Velica, S.; Vigilante, M.; Fazia Collaboration

    2009-07-01

    Current and charge signals have been collected for Se ions at 408 MeV, S at 160 MeV and Ni at 703 MeV, all stopped in silicon detectors. Some detectors were cut 0∘ off the axis and some off the axis. Important effects on the shape of the silicon current and charge signals have been observed, depending on the orientation of the impinging ion relative to the crystal axes and planes. A degradation of the energy and risetime resolution of about a factor ˜3 with respect to the measured optimal values (for example 7∘ off-axis orientation) is observed for ion impinging directions close to crystal axes and/or planes, i.e. the common scenario for normal incidence on 0∘ cut detectors. For Pulse Shape Analysis applications, the necessity of using such "random" oriented silicon detectors is demonstrated.

  1. Influence of crystal-orientation effects on pulse-shape-based identification of heavy-ions stopped in silicon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bardelli, L. [University of Florence (Italy); I.N.F.N. Sezione di Firenze (Italy)], E-mail: bardelli@fi.infn.it; Bini, M. [University of Florence (Italy); I.N.F.N. Sezione di Firenze (Italy); Casini, G. [I.N.F.N. Sezione di Firenze (Italy); Pasquali, G.; Poggi, G. [University of Florence (Italy); I.N.F.N. Sezione di Firenze (Italy); Barlini, S. [LPC Caen, ENSICAEN, Universite de Caen, CNRS/IN2P3, Caen (France); Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay cedex (France); Becla, A. [Jagiellonian University, Institute of Physics, Reymonta 4, 30-059 Krakow (Poland); Berjillos, R. [Departamento de Fisica Aplicada, Universidad de Huelva, E-21071 Huelva (Spain); Borderie, B. [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay cedex (France); Bougault, R. [LPC Caen, ENSICAEN, Universite de Caen, CNRS/IN2P3, Caen (France); Bruno, M. [University of Bologna (Italy); I.N.F.N. Sezione di Bologna (Italy); Cinausero, M. [I.N.F.N. Laboratori Nazionali di Legnaro (Italy); D' Agostino, M.; De Sanctis, J. [University of Bologna (Italy); I.N.F.N. Sezione di Bologna (Italy); Duenas, J.A. [Departamento de Fisica Aplicada, Universidad de Huelva, E-21071 Huelva (Spain); Edelbruck, P. [Institut de Physique Nucleaire, CNRS/IN2P3, Universite Paris-Sud 11, F-91406 Orsay cedex (France); Geraci, E. [University of Bologna (Italy); I.N.F.N. Sezione di Bologna (Italy); Gramegna, F. [I.N.F.N. Laboratori Nazionali di Legnaro (Italy); Kordyasz, A. [Heavy Ion Laboratory, Warsaw University, Pasteura 5a, 02-093 Warsaw (Poland); Kozik, T. [Jagiellonian University, Institute of Physics, Reymonta 4, 30-059 Krakow (Poland)] (and others)

    2009-07-01

    Current and charge signals have been collected for Se ions at 408 MeV, S at 160 MeV and Ni at 703 MeV, all stopped in silicon detectors. Some detectors were cut 0 deg. off the <111> axis and some off the <100> axis. Important effects on the shape of the silicon current and charge signals have been observed, depending on the orientation of the impinging ion relative to the crystal axes and planes. A degradation of the energy and risetime resolution of about a factor {approx}3 with respect to the measured optimal values (for example 7 deg. off-axis orientation) is observed for ion impinging directions close to crystal axes and/or planes, i.e. the common scenario for normal incidence on 0 deg. cut detectors. For Pulse Shape Analysis applications, the necessity of using such 'random' oriented silicon detectors is demonstrated.

  2. How do copper contamination pulses shape the regime shifts of phytoplankton-zooplankton dynamics?

    Science.gov (United States)

    Camara, B. I.; Yamapi, R.; Mokrani, H.

    2017-07-01

    The presence of pollutants in waters, particularly from heavy metals, is of grave concern worldwide due to its cytotoxicity to organisms. Fish and aquatic organisms are very sensitive to the increasing Cu concentrations in water. Therefore, Cu toxicity partly depends on water quality. To address the effects of impulsive copper contamination of the phytoplankton-zooplankton population dynamics, we've built a model that focuses on the interaction between algae and Daphnia with deterministic and stochastic impulse copper. In fact the Results have shown three types of outcomes depending on copper concentration. In low (4.4 μgL-1) copper concentration, deterministic and stochastic pulses may promote the persistence of Daphnia and algae populations unlike the absence of pulses. Whereas, in high (28 μgL-1) concentration, it accelerates deficiency and toxicity processes, leads to the extinction of all populations and in intermediate concentrations. Deterministic and stochastic pulses may transform population dynamics in complex oscillations. Numerical results show that the system that has been considered has more complex dynamics including bifurcation, period-doubling oscillations and chaos. Depending on minimum copper concentration in the environment, the bifurcation diagram has highlighted the resilience or the regime shifts of the system in occurrence of pulse contamination.

  3. Is there an Optimal Shape of the Defibrillation Shock: Constant Current vs. Pulsed Biphasic Waveforms

    Directory of Open Access Journals (Sweden)

    Ivan Dotsinsky

    2013-04-01

    Full Text Available Three waveforms for transthoracic defibrillation are assessed and compared: the Pulsed Biphasic Waveform (PBW, the Rectilinear Biphasic Waveform (RBW, and the "lossless" constant current (LLCC pulses. Two indices are introduced: 1 kf = W/W0 - the ratio between the delivered energy W and the energy W0 of a rectangular pulse with the same duration and electric charge; 2 ηC = W/WC0 - the level of utilizing the initially loaded capacitor energy WC0. The envisioned comparative study shows that ηC index is favorable for both PBW and LLCC, while kf of both RBW and LLCC demonstrates advantage over the PBW in the range of small inter-electrode thoracic impedances below 80 Ω. Some design considerations are also discussed. The attractive LLCC concept needs large and heavy inductive coil to support the constant current amplitude, besides it is capable to induce strong electromagnetic influences due to the complex current control. The RBW technology controls the delivery of current through a series of internal resistors which are, however, a source of high heat losses. The PBW implements controlled duty cycle of high-frequency chopped pulses to adapt the energy delivery in respect of the patient impedance measured at the beginning of the shock. PBW technology makes use of small capacitors which allows the construction of light weight and small-size portable devices for transthoracic defibrillation.

  4. Instantaneous nonvertical electronic transitions with shaped femtosecond laser pulses: Is it possible?

    DEFF Research Database (Denmark)

    Henriksen, Niels Engholm; Møller, Klaus Braagaard

    2003-01-01

    In molecular electronic transitions, a vertical transition can be induced by an ultrashort laser pulse. That is, a replica of the initial nuclear state-times the transition dipole moment of the electronic transition-can be created instantaneously (on the time scale of nuclear motion) in the excited...

  5. Signal recognition efficiencies of artificial neural-network pulse-shape discrimination in HPGe 0νββ-decay searches

    Energy Technology Data Exchange (ETDEWEB)

    Caldwell, A.; Cossavella, F.; Majorovits, B.; Palioselitis, D.; Volynets, O. [Max-Planck-Institut fuer Physik, Munich (Germany)

    2015-07-15

    A pulse-shape discrimination method based on artificial neural networks was applied to pulses simulated for different background, signal and signal-like interactions inside a germanium detector. The simulated pulses were used to investigate variations of efficiencies as a function of used training set. It is verified that neural networks are well-suited to identify background pulses in true-coaxial high-purity germanium detectors. The systematic uncertainty on the signal recognition efficiency derived using signal-like evaluation samples from calibration measurements is estimated to be 5 %. This uncertainty is due to differences between signal and calibration samples. (orig.)

  6. The Impact of Photon Flight Path on S1 Pulse Shape Analysis in Liquid Xenon Two-phase Detectors

    CERN Document Server

    Moongweluwan, M

    2015-01-01

    The LUX dark matter search experiment is a 350 kg dual-phase xenon time projection chamber located at the 4850 ft level of the Sanford Underground Research Facility in Lead, SD. The success of two-phase xenon detectors for dark matter searches relies on their ability to distinguish electron recoil (ER) background events from nuclear recoil (NR) signal events. Typically, the NR-ER discrimination is obtained from the ratio of the electroluminescence light (S2) to the prompt scintillation light (S1). Analysis of the S1 pulse shape is an additional discrimination technique that can be used to distinguish NR from ER. Pulse-shape NR-ER discrimination can be achieved based on the ratio of the de-excitation processes from singlet and triplet states that generate the S1. The NR S1 is dominated by the de-excitation process from singlet states with a time constant of about 3 ns while the ER S1 is dominated by the de-excitation process from triplet states with a time constant of about 24 ns. As the size of the detectors ...

  7. A Ring-shaped photodiode designed for use in a reflectance pulse oximetry sensor in wireless health monitoring applications

    DEFF Research Database (Denmark)

    Duun, Sune; Haahr, Rasmus Grønbek; Birkelund, Karen

    2010-01-01

    We report a photodiode for use in a reflectance pulse oximeter for use in autonomous and low-power homecare applications. The novelty of the reflectance pulse oximeter is a large ring shaped backside silicon pn photodiode. The ring-shaped photodiode gives optimal gathering of light and thereby en...... is demonstrated to work in a laboratory setup with a Ledtronics dual LED with wavelengths of 660 and 940 nm. Using this setup photoplethysmograms which clearly show the cardiovascular cycle have been recorded. The sensor is shown to work very well with low currents of less than 10 mA....... a radius of 3.68 mm and a width of 0.78 mm giving an area of 18 mm2. The capacitance of the photodiode is measured to 34.5 nF. The quantum efficiency of the photodiode is measured to 55% and 62% at 660 nm and 940 nm, respectively. It is acceptable for this prototype but can be improved. The sensor also has...

  8. Pulse-shape discrimination and energy quenching of alpha particles in Cs$_2$LiLaBr$_6$:Ce$^{3+}$

    CERN Document Server

    Mesick, Katherine E; Stonehill, Laura C

    2016-01-01

    Cs$_2$LiLaBr$_6$:Ce$^{3+}$ (CLLB) is an elpasolite scintillator that offers excellent linearity and gamma-ray energy resolution and sensitivity to thermal neutrons with the ability to perform pulse-shape discrimination (PSD) to distinguish gammas and neutrons. Our investigation of CLLB has indicated the presence of intrinsic radioactive alpha background that we have determined to be from actinium contamination of the lanthanum component. We measured the pulse shapes for gamma, thermal neutron, and alpha events and determined that PSD can be performed to separate the alpha background with a moderate figure of merit of 0.98. We also measured the electron-equivalent-energy of the alpha particles in CLLB and simulated the intrinsic alpha background from $^{227}$Ac to determine the quenching factor of the alphas. A linear quenching relationship $L_{\\alpha} = E_{\\alpha} \\times q + L_0$ was found at alpha particle energies above 5 MeV, with a quenching factor $q = 0.71$ MeVee/MeV and an offset $L_0 = - 1.19$ MeVee.

  9. Unidirectional Amplification and Shaping of Optical Pulses by Three-Wave Mixing with Negative Phonons

    CERN Document Server

    Popov, Alexander K; Myslivets, Sergey A; Slabko, Vitaly V

    2013-01-01

    A possibility to greatly enhance frequency-conversion efficiency of stimulated Raman scattering is shown by making use of extraordinary properties of three-wave mixing of ordinary and backward waves. Such processes are commonly attributed to negative-index plasmonic metamaterials. This work demonstrates the possibility to replace such metamaterials that are very challenging to engineer by readily available crystals which support elastic waves with contra-directed phase and group velocities. The main goal of this work is to investigate specific properties of indicated nonlinear optical process in short pulse regime and to show that it enables elimination of fundamental detrimental effect of fast damping of optical phonons on the process concerned. Among the applications is the possibility of creation of a family of unique photonic devices such as unidirectional Raman amplifiers and femtosecond pulse shapers with greatly improved operational properties.

  10. Subwavelength ripples adjustment based on electron dynamics control by using shaped ultrafast laser pulse trains.

    Science.gov (United States)

    Jiang, Lan; Shi, Xuesong; Li, Xin; Yuan, Yanping; Wang, Cong; Lu, Yongfeng

    2012-09-10

    This study reveals that the periods, ablation areas and orientations of periodic surface structures (ripples) in fused silica can be adjusted by using designed femtosecond (fs) laser pulse trains to control transient localized electron dynamics and corresponding material properties. By increasing the pulse delays from 0 to 100 fs, the ripple periods are changed from ~550 nm to ~255 nm and the orientation is rotated by 90°. The nearwavelength/subwavelength ripple periods are close to the fundamental/second-harmonic wavelengths in fused silica respectively. The subsequent subpulse of the train significantly impacts free electron distributions generated by the previous subpulse(s), which might influence the formation mechanism of ripples and the surface morphology.

  11. Advanced Techniques and Antenna Design for Pulse Shaping in UWB Cognitive Radio

    Directory of Open Access Journals (Sweden)

    Lise Safatly

    2012-01-01

    Full Text Available Spectrum scarcity has emerged as a primary problem in the communications technology. The combination of cognitive radio (CR and ultra-wideband impulse radio (UWB-IR has been proposed to solve the shortage problem by allowing smart and adaptive spectrum management, leading to UWB-CR. In a UWB-CR scheme, secondary users are supposed to ensure interference avoidance by adaptively selecting the portions of the spectrum not being used by primary users. In this paper, three different techniques for the generation of adaptive UWB pulses are studied. The Parks-McClellan algorithm is employed, a neural network is trained, and a reconfigurable band stop filter is designed to generate an adaptive waveform with nulls at specific frequencies. Simulations, measurements, and analysis show that each generated UWB pulse has remarkable advantages in the frequency utilization, spectrum avoidance, and hardware implementation.

  12. High-brightness X-ray free-electron laser with an optical undulator by pulse shaping.

    Science.gov (United States)

    Chang, Chao; Liang, Jinyang; Hei, Dongwei; Becker, Michael F; Tang, Kelei; Feng, Yiping; Yakimenko, Vitaly; Pellegrini, Claudio; Wu, Juhao

    2013-12-30

    A normal-incident flattop laser with a tapered end is proposed as an optical undulator to achieve a high-gain and high-brightness X-ray free electron laser (FEL). The synchronic interaction of an electron bunch with the normal incident laser is realized by tilting the laser pulse front. The intensity of the flattop laser is kept constant during the interaction time of the electron bunch and the laser along the focal plane of a cylindrical lens. Optical shaping to generate the desired flattop pulse with a tapered end from an original Gaussian pulse distribution is designed and simulated. The flattop laser with a tapered end can enhance the X-ray FEL beyond the exponential growth saturation power by one order to reach 1 Gigawatt as compared to that without a tapered end. The peak brightness can reach 1030 photons/mm2/mrad2/s/0.1% bandwidth, more than 10 orders brighter than the conventional incoherent Thompson Scattering X-ray source.

  13. Pulse shape discrimination properties of Gd3Ga3Al2O12:Ce,B single crystal in comparison with CsI:Tl

    Science.gov (United States)

    Rawat, S.; Tyagi, Mohit; Netrakanti, P. K.; Kashyap, V. K. S.; Mitra, A.; Singh, A. K.; Desai, D. G.; Kumar, G. Anil; Gadkari, S. C.

    2016-12-01

    Single crystals of Gd3Ga3Al2O12:Ce,B and CsI:Tl were grown by Czochralski and Bridgman techniques, respectively. While both the crystals exhibited similar emission at about 550 nm, their scintillation decay times showed significantly different characteristics. The average scintillation decay time of Gd3Ga3Al2O12:Ce,B crystal was found to be about 284 ns for alpha excitation compared to 108 ns measured for a gamma source. On the other hand in CsI:Tl crystals, the alpha excitation resulted in a lower average decay time of 600 ns compared to 1200 ns with gamma excitation. Their pulse shape discrimination (PSD) for gamma and alpha radiations were studied by coupling the scintillators with photomultiplier tube or SiPM and employing an advanced digitizer as well as a conventional zero-crossing setup. In spite of having a poor α/γ light yield ratio, the PSD figure of merit and the difference of zero-crossing time in Gd3Ga3Al2O12:Ce,B crystals were found to be superior in comparison to CsI:Tl crystals.

  14. Bi-Annual Report 2010-2011: Shaping pulse flows to meet environmental and energy objectives

    Energy Technology Data Exchange (ETDEWEB)

    Jager, Yetta [ORNL

    2010-10-01

    This report describes a bioenergetic model developed to allocate seasonal pulse flows to benefit salmon growth. The model links flow with floodplain inundation and production of invertebrate prey eaten by juvenile Chinook salmon. A unique quantile modeling approach is used to describe temporal variation among juvenile salmon spawned at different times. Preliminary model outputs are presented and future plans to optimize flows both to maximize salmon growth and hydropower production are outlined.

  15. Temporally Shaped Current Pulses on a Two-Cavity Linear Transformer Driver System

    Science.gov (United States)

    2011-06-01

    system was triggered. The digitizers were triggered by a reference voltage divider from a 20 kV thyratron pulser, which also triggers the master high...measured from the calibrated voltage and current monitors. The simulations use the Martin [15] arc discharge switch resistance model . The gas...switches use dry air at 3 bar pressure; the gas type, pressure, and gap are all used in the switch model to calculate self-consistently the dynamic

  16. A pulse-shaping technique to investigate the behaviour of brittle materials subjected to plate-impact tests

    Science.gov (United States)

    Forquin, Pascal; Zinszner, Jean-Luc

    2017-01-01

    Owing to their significant hardness and compressive strengths, ceramic materials are widely employed for use with protective systems subjected to high-velocity impact loadings. Therefore, their mechanical behaviour along with damage mechanisms need to be significantly investigated as a function of loading rates. However, the classical plate-impact testing procedures produce shock loadings in the brittle sample material which cause unrealistic levels of loading rates. Additionally, high-pulsed power techniques and/or functionally graded materials used as flyer plates to smooth the loading pulse remain costly, and are generally difficult to implement. In this study, a shockless plate-impact technique based on the use of either a wavy-machined flyer plate or buffer plate that can be produced by chip-forming is proposed. A series of numerical simulations using an explicit transient dynamic finite-element code have been performed to design and validate the experimental testing configuration. The calculations, conducted in two-dimensional (2D) plane-strain or in 2D axisymmetric modes, prove that the `wavy' contact surface will produce a pulse-shaping effect, whereas the buffer plate will produce a homogenizing effect of the stress field along the transverse direction of the sample. In addition, `wavy-shape' geometries of different sizes provide an easy way to change the level of loading rate and rise time in an experimentally tested ceramic specimen. Finally, when a shockless compression loading method is applied to the sample, a Lagrangian analysis of data is made possible by considering an assemblage of ceramic plates of different thicknesses in the target, so the axial stress-strain response of the brittle sample material can be provided. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  17. Vascular stiffness determined from a nocturnal digital pulse wave signal: association with sleep, sleep-disordered breathing, and hypertension.

    Science.gov (United States)

    Svedmyr, Sven; Zou, Ding; Sommermeyer, Dirk; Ficker, Joachim H; Randerath, Winfried; Fietze, Ingo; Sanner, Bernd; Hedner, Jan; Grote, Ludger

    2016-12-01

    Reflection of the finger pulse wave form is a valid measure of arterial stiffness, which may be continuously assessed during sleep. We investigated the relationships between sleep, sleep-disordered breathing, hypertension, and pulse propagation time (PPT) in patients with suspected sleep apnea. The digital photoplethysmographic signal derived from finger pulse oximetry was recorded during overnight sleep studies in 440 patients (64% men, age 55 ± 12 years, BMI 30 ± 6 kg/m, apnea-hypopnea index 19 ± 19 n/h). PPT, defined as the time interval between the systolic and diastolic peak of the finger pulse wave, was calculated. The influence of sleep stages on PPT were assessed in patients undergoing polysomnography. Generalized linear models were used to study predictors of PPT and hypertension. Mean overnight PPT was independently associated with age (β = -1.34, P PPT was shorter in hypertensive patients compared with normotensive patients (160 ± 33 vs. 177 ± 47 ms, P PPT was influenced by sleep stage (highest PPT during slow wave sleep compared with wake and all other sleep stages, all P PPT by oximetry was strongly associated with factors known to determine daytime vascular stiffness. In addition, PTT provides information on functional and structural vascular properties during sleep. This novel technique offers new opportunities to noninvasively monitor vascular function during the sleeping period.

  18. A Robust Digital Autopilot for Spacecraft Equipped with Pulse-Operated Thrusters

    Science.gov (United States)

    Thurman, S. W.; Flashner, H.

    1996-01-01

    The analysis and design of attitude control systems for spacecraft employing pulse-operated (on-off) thrusters is usually accomplished through a combination of modeling approximations and empirical techniques. In this paper a new thruster pulse-modulation scheme for pointing and tracking applications is developed from nonlinear control theory.

  19. PULSE REFERENCED CONTROL METHOD FOR ENHANCED POWER AMPLIFICATION OF A PULSE MODULATED SIGNAL

    DEFF Research Database (Denmark)

    1998-01-01

    (v¿e?); a state feedback block A with compensation; a reference shaping block $i(R) to modify the pulsed reference $i(v¿r?) for optimized error estimation; a difference block to generate an error signal and a compensator $i(C) to shape this error. The invention makes it possible to implement practical digital...

  20. Analysis on the joint tensile strength and fractography of TiNi shape memory alloy precise pulse resistance butt welding

    Institute of Scientific and Technical Information of China (English)

    赵熹华; 韩立军; 赵蕾

    2002-01-01

    This paper studies mechanical property and fractography of the welded joints obtained in different welding parameters such as welding heat and welding press with/without gas shield in TiNi shape memory alloy precise pulse resistance butt welding using tensile strength test, XRD, SEM and TEM measures. The optimum welding parameters obtaining high tensile strength welded joint are got. On the condition of welding press magneting current 2 A and welding heat 75%, the joint strength is the highest. This is important for to study other properties of TiNi shape memory alloy further. The experimental results state that argon gas shield have different effects on different welding parameters, less on welding press, but great on welding heat. But excessive welding press and welding heat have great effects on joint tensile strength. Too high welding heat can produce the new intermetallic compound, this intermetallic compound lead to dislocation density to increase and form the potential crack initiation, which can easily make the joint fracture under stress effect and decrease the shape memory ratio of joint for high density dislocation groups existing in the twinned martensite.

  1. Enhancing ablation efficiency in micro structuring using a deformable mirror for beam shaping of ultra-short laser pulses

    Science.gov (United States)

    Smarra, M.; Dickmann, K.

    2016-03-01

    Using ultra-short laser pulses for the generation of microstructures results in a high flexible tool for free form geometries in the micro range. Increasing laser power and repetition rates increase as well the demand of high flexible and efficient process strategies. To increase the ablation efficiency the optimal fluency can be determined, which is a material specific value. By varying the beam shape, the ablation efficiency can be enhanced. In this study a deformable mirror was used to vary the beam shape. This mirror is built by combining a piezo-electric ceramic and a mirror substrate. The ceramic is divided into several segments, which can be controlled independently. This results in a high flexible deformable mirror which influences the beam shape and can be used to vary the spot size or generate line geometries. The ablation efficiency and roughness of small generated cavities were analyzed in this study as well as the dimensions of the cavity. This can be used to optimize process strategies to combine high volume ablation and fine detail generation.

  2. Shifting the boundaries: pulse-shape effects in the atom-optics kicked rotor

    CERN Document Server

    Jones, P H; Meacher, D R

    2003-01-01

    We present the results of experiments performed on cold caesium in a pulsed sinusoidal optical potential created by counter-propagating laser beams having a small frequency difference in the laboratory frame. Since the atoms, which have average velocity close to zero in the laboratory frame, have non-zero average velocity in the co-moving frame of the optical potential, we are able to centre the initial velocity distribution of the cloud at an arbitrary point in phase-space. In particular, we demonstrate the use of this technique to place the initial velocity distribution in a region of phase-space not accessible to previous experiments, namely beyond the momentum boundaries arising from the finite pulse duration of the potential. We further use the technique to explore the kicked rotor dynamics starting from a region of phase-space where there is a strong velocity dependence of the diffusion constant and quantum break time and demonstrate that this results in a marked asymmetry in the chaotic evolution of th...

  3. Satellite and Opacity Effects on Resonance Line Shapes Produced from Short-Pulse Laser Heated Foils

    Energy Technology Data Exchange (ETDEWEB)

    Shepherd, R; Audebert, P; Chen, H-K; Fournier, K B; Peyreusse, O; Moon, S; Lee, R W; Price, D; Klein, L; Gauthier, J C; Springer, P

    2002-12-03

    We measure the He-like, time-resolved emission from thin foils consisting of 250 {angstrom} of carbon-250 {angstrom} of aluminum and 500 {angstrom} aluminum illuminated with a 150 fs laser pulse at an intensity of 1 x 10{sup 19} W/cm{sup 2}. Dielectronic satellite contributions to the 1s{sup 2}-1s2p({sup 1}P), 1s{sup 2}-1s3p({sup 1}P), and 1s{sup 2}1s4p({sup 1}P) line intensities are modeled using the configuration averaged code AVERROES and is found to be significant for all three resonance lines. The contribution of opacity broadening is inferred from the data and found to be significant only in the 1s{sup 2}-1s2p({sup 1}P).

  4. Pulse shape analysis for segmented germanium detectors implemented in graphics processing units

    Energy Technology Data Exchange (ETDEWEB)

    Calore, Enrico, E-mail: enrico.calore@lnl.infn.it [INFN Laboratori Nazionali di Legnaro, Viale Dell' Università 2, I-35020 Legnaro, Padova (Italy); Bazzacco, Dino, E-mail: dino.bazzacco@pd.infn.it [INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Recchia, Francesco, E-mail: francesco.recchia@pd.infn.it [INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Dipartimento di Fisica e Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy)

    2013-08-11

    Position sensitive highly segmented germanium detectors constitute the state-of-the-art of the technology employed for γ-spectroscopy studies. The operation of large spectrometers composed of tens to hundreds of such detectors demands enormous amounts of computing power for the digital treatment of the signals. The use of Graphics Processing Units (GPUs) has been evaluated as a cost-effective solution to meet such requirements. Different implementations and the hardware constraints limiting the performance of the system are examined. -- Highlights: • We implemented the grid-search algorithm in OpenCL in order to be run on GPUs. • We compared its performances in respect to an optimized CPU implementation in C++. • We analyzed the results highlighting the most probable factors limiting their speed. • We propose some solutions to overcome their speed limits.

  5. Using pulse shape analysis to improve the position resolution of a resistive anode microchannel plate detector

    CERN Document Server

    Siwal, Davinder; deSouza, R T

    2015-01-01

    Digital signal processing techniques were employed to investigate the joint use of charge division and risetime analyses for the resistive anode (RA) coupled to a microchannel plate detector (MCP). In contrast to the typical approach of using the relative charge at each corner of the RA, this joint approach results in a significantly improved position resolution. A conventional charge division analysis utilizing analog signal processing provides a position measured resolution of 170 $\\mu$m (FWHM). By using the correlation between risetime and position we were able to obtain a measured resolution of 92 $\\mu$m (FWHM), corresponding to an intrinsic resolution of 64 $\\mu$m (FMHM) for a single Z-stack MCP detector.

  6. Optimizing pulse shaping and zooming for acceleration to high velocities and fusion neutron production on the Nike laser

    Science.gov (United States)

    Karasik, Max; Weaver, J. L.; Aglitskiy, Y.; Zalesak, S. T.; Velikovich, A. L.; Oh, J.; Obenschain, S. P.; Arikawa, Y.; Watari, T.

    2010-11-01

    We will present results from follow-on experiments to the record-high velocities of 1000 km/s achieved on Nike [Karasik et al., Phys. Plasmas 17, 056317 (2010) ], in which highly accelerated planar foils of deuterated polystyrene were made to collide with a witness foil to produce extreme shock pressures and result in heating of matter to thermonuclear temperatures. Still higher velocities and higher target densities are required for impact fast ignition. The aim of these experiments is shaping the driving pulse to minimize shock heating of the accelerated target and using the focal zoom capability of Nike to achieve higher densities and velocities. Spectroscopic measurements of electron temperature achieved upon impact will complement the neutron time-of-flight ion temperature measurement. Work is supported by US DOE and Office of Naval Research.

  7. Design and development of an ultra-compact drum-shaped chamber for combinatorial pulsed laser deposition

    Science.gov (United States)

    Katayama, M.; Itaka, K.; Matsumoto, Y.; Koinuma, H.

    2006-01-01

    We have designed a compact combinatorial pulsed laser deposition (PLD) chamber as a building block of a desktop laboratory for advanced materials research. Development of small-size systems for the growth and characterization of films would greatly help in interconnecting a variety of analytical tools for rapid screening of advanced materials. This PLD chamber has four special features: (1) a drum-shaped growth chamber, (2) a waterwheel-like combinatorial masking system, (3) a multi-target system having one feedthrough, and (4) a small reflection high-energy electron diffraction (RHEED) system. The performance of this system is demonstrated by the RHEED intensity oscillation during homoepitaxial growth of SrTiO 3 as well as by simultaneous fabrication of a ternary phase diagram of rare earth-doped Y 2O 3 phosphors.

  8. A Simple Exact Error Rate Analysis for DS-CDMA with Arbitrary Pulse Shape in Flat Nakagami Fading

    Science.gov (United States)

    Rahman, Mohammad Azizur; Sasaki, Shigenobu; Kikuchi, Hisakazu; Harada, Hiroshi; Kato, Shuzo

    A simple exact error rate analysis is presented for random binary direct sequence code division multiple access (DS-CDMA) considering a general pulse shape and flat Nakagami fading channel. First of all, a simple model is developed for the multiple access interference (MAI). Based on this, a simple exact expression of the characteristic function (CF) of MAI is developed in a straight forward manner. Finally, an exact expression of error rate is obtained following the CF method of error rate analysis. The exact error rate so obtained can be much easily evaluated as compared to the only reliable approximate error rate expression currently available, which is based on the Improved Gaussian Approximation (IGA).

  9. Neutron calibration facility with an Am-Be source for pulse shape discrimination measurement of CsI(Tl) crystals

    CERN Document Server

    Lee, H S; Choi, J H; Choi, S; Hahn, I S; Jeon, E J; Joo, H W; Kang, W G; Kim, G B; Kim, H J; Kim, K W; Kim, S C; Kim, S K; Kim, Y D; Kim, Y H; Lee, J H; Lee, J K; Leonard, D S; Li, J; Myung, S S; Olsen, S L; So, J H

    2014-01-01

    We constructed a neutron calibration facility based on a 300-mCi Am-Be source in conjunction with a search for weakly interacting massive particle candidates for dark matter. The facility is used to study the response of CsI(Tl) crystals to nuclear recoils induced by neutrons from the Am-Be source and comparing them with the response to electron recoils produced by Compton scattering of 662-keV $\\gamma$-rays from a $^{137}$Cs source. The measured results on pulse shape discrimination (PSD) between nuclear- and electron-recoil events are quantified in terms of quality factors. A comparison with similar result from a neutron reactor demonstrate the feasibility of performing calibrations of PSD measurements using neutrons from a Am-Be source.

  10. Coherent diffraction imaging analysis of shape-controlled nanoparticles with focused hard X-ray free-electron laser pulses.

    Science.gov (United States)

    Takahashi, Yukio; Suzuki, Akihiro; Zettsu, Nobuyuki; Oroguchi, Tomotaka; Takayama, Yuki; Sekiguchi, Yuki; Kobayashi, Amane; Yamamoto, Masaki; Nakasako, Masayoshi

    2013-01-01

    We report the first demonstration of the coherent diffraction imaging analysis of nanoparticles using focused hard X-ray free-electron laser pulses, allowing us to analyze the size distribution of particles as well as the electron density projection of individual particles. We measured 1000 single-shot coherent X-ray diffraction patterns of shape-controlled Ag nanocubes and Au/Ag nanoboxes and estimated the edge length from the speckle size of the coherent diffraction patterns. We then reconstructed the two-dimensional electron density projection with sub-10 nm resolution from selected coherent diffraction patterns. This method enables the simultaneous analysis of the size distribution of synthesized nanoparticles and the structures of particles at nanoscale resolution to address correlations between individual structures of components and the statistical properties in heterogeneous systems such as nanoparticles and cells.

  11. Pulsed Airborne Lidar Measurements of Atmospheric CO2 Column Absorption and Line Shapes from 3-13 km Altitudes

    Science.gov (United States)

    Abshire, James; Riris, Haris; Allan, Graham; Weaver, Clark; Mao, Jianping; Sun, Xiaoli; Hasselbrack, William

    2010-01-01

    We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's planned ASCENDS space mission. Our technique uses two pulsed laser transmitters allowing simultaneous measurement of a CO2 absorption line in the 1570 nm band, O2 extinction in the Oxygen A-band and surface height and backscatter. The lidar measures the energy and time of flight of the laser echoes reflected from the atmosphere and surface. The lasers are rapidly and precisely stepped in wavelength across the CO2 line and an O2 line region during the measurement. The direct detection receiver uses a telescope and photon counting detectors, and measures the background light and energies of the laser echoes from the surface along with scattering from any aerosols in the path. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off- line signals via the DIAL technique. Time gating is used to isolate the laser echo signals from the surface, and to reject laser photons scattered in the atmosphere. The time of flight of the laser pulses are also used to estimate the height of the scattering surface and to identify cases of mixed cloud and ground scattering. We have developed an airborne lidar to demonstrate the CO2 measurement from the NASA Glenn Lear-25 aircraft. The airborne lidar steps the pulsed laser's wavelength across the selected CO2 line with 20 steps per scan. The line scan rate is 450 Hz, the laser pulse widths are 1 usec, and laser pulse energy is 24 uJ. The time resolved laser backscatter is collected by a 20 cm telescope, detected by a photomultiplier and is recorded by a photon counting system. We made initial airborne measurements on flights during fall 2008. Laser backscatter and absorption measurements were made over a variety of land and water surfaces and through thin clouds. The atmospheric CO2 column measurements using the 1572.33 nm CO2 lines. Two flights were made above the

  12. Phase-only shaped laser pulses in optimal control theory: application to indirect photofragmentation dynamics in the weak-field limit.

    Science.gov (United States)

    Shu, Chuan-Cun; Henriksen, Niels E

    2012-01-28

    We implement phase-only shaped laser pulses within quantum optimal control theory for laser-molecule interaction. This approach is applied to the indirect photofragmentation dynamics of NaI in the weak-field limit. It is shown that optimized phase-modulated pulses with a fixed frequency distribution can substantially modify transient dissociation probabilities as well as the momentum distribution associated with the relative motion of Na and I.

  13. Mid-Infrared Pulse Shaping and Two-Dimensional Spectroscopy of Open Quantum Systems in Liquid Solution

    Science.gov (United States)

    Ross, Matthew R.

    The primary focus of this work is the development of a mid-infrared pulse shaping system. The primary motivation for this system is for two-dimensional infrared (2DIR) spectroscopy, however, the mid-infrared pulse shaper also allows for more sophisticated spectroscopic experiments not previously attempted in the mid-infrared. Moreover, many can be implemented without changes or realignment of the optical setup. Example spectra are presented along with a discussion of capabilities and diagnostics. A second major project presented is 2DIR spectroscopy of iron pentacarbonyl, Fe(CO)5, a small metal carbonyl. This molecule undergoes Berry pseudorotation, a form of fluxtionality. This fast exchange of ligands mixes axial and equatorial modes and occurs on a timescale of picoseconds, too fast for NMR and other methods of measuring chemical structure and isomerization. Ultrafast chemical exchange spectroscopy, a measurement within 2DIR spectroscopy, is capable of resolving the time scales of this motion. We found that this process is affected by the solvent environment, specifically the solvent viscosity in alkanes and hydrogen bonding environments in alcohols. Lastly, a study is presented in which a series of synthetic metalloenzymes with a metal active site are studied by 2DIR spectroscopy. In this case a carbonyl is ligated to a copper-I atom in the active site, which then serves as our spectroscopic probe. We find, unexpectedly, that the shape of the carbonyl vibrational potential, as measured by the anharmonicity, is time-dependent. We attribute this to a geometrical rearrangement and are able to suggest that this effect is dependent on local site structure and dynamics and not significantly affected by electric potential near the peptide.

  14. EJ-309 pulse shape discrimination performance with a high gamma-ray-to-neutron ratio and low threshold

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, A.C., E-mail: Alexis.C.Kaplan@gmail.com [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Blvd., Ann Arbor, MI 48104 (United States); Nuclear Engineering and Nonproliferation Division, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Flaska, M.; Enqvist, A.; Dolan, J.L.; Pozzi, S.A. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Blvd., Ann Arbor, MI 48104 (United States)

    2013-11-21

    Measuring neutrons in the presence of high gamma-ray fluence is a challenge with multi-particle detectors. Organic liquid scintillators such as the EJ-309 are capable of accurate pulse-shape discrimination (PSD) but the chance for particle misclassification is not negligible for some applications. By varying the distance from an EJ-309 scintillator to a strong-gamma-ray source and keeping a weak-neutron source at a fixed position, various gamma-to-neutron ratios can be measured and PSD performance can be quantified. Comparing neutron pulse-height distributions allows for pulse-height specific PSD evaluation, and quantification and visualization of deviation from {sup 252}Cf alone. Even with the addition of the misclassified gamma-rays, the PSD is effective in separating particles so that neutron count rate can be predicted with less than 10% error up to a gamma-to-neutron ratio of almost 650. For applications which can afford a reduction in neutron detection efficiency, PSD can be sufficiently effective in discriminating particles to measure a weak neutron source in a high gamma-ray background. -- Highlights: •We measure neutrons in a high photon background with EJ-309 liquid scintillators. •A low threshold is used to test the limits of particle discrimination. •A weak neutron signal is detectable with a gamma/neutron ratio as high as 770. •Photon pileup most commonly adds to error in classification of neutrons. •Neutron count rates are within 10% of expected rate under high gamma background.

  15. Pulse shape analysis of a two fold clover detector with an EMD based new algorithm: A comparison

    Energy Technology Data Exchange (ETDEWEB)

    Siwal, Davinder, E-mail: dev84sonu@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Mandal, S. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Palit, R.; Sethi, J. [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Garg, R. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Saha, S. [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Prasad, Awadhesh [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Chavan, P.B.; Naidu, B.S.; Jadhav, S.; Donthi, R. [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Schaffner, H.; Adamczewski-Musch, J.; Kurz, N.; Wollersheim, H.J. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Singh, R. [Amity Institute of Nuclear Science and Technology, Amity University, Noida 201303 (India)

    2014-03-21

    An investigation of Empirical Mode Decomposition (EMD) based noise filtering algorithm has been carried out on a mirror signal from a two fold germanium clover detector. EMD technique can decompose linear as well as nonlinear and chaotic signals with a precise frequency resolution. It allows to decompose the preamplifier signal (charge pulse) on an event-by-event basis. The filtering algorithm provides the information about the Intrinsic Mode Functions (IMFs) mainly dominated by the noise. It preserves the signal information and separates the overriding noise oscillations from the signals. The identification of noise structure is based on the frequency distributions of different IMFs. The preamplifier noise components which distort the azimuthal co-ordinates information have been extracted on the basis of the correlation between the different IMFs and the mirror signal. The correlation studies have been carried out both in frequency and time domain. The extracted correlation coefficient provides an important information regarding the pulse shape of the γ-ray interaction in the detector. A comparison between the EMD based and state-of-the-art wavelet based denoising techniques has also been made and discussed. It has been observed that the fractional noise strength distribution varies with the position of the collimated gamma-ray source. Above trend has been reproduced by both the denoising techniques.

  16. Spatial Laser Beam Shaping Using Digital Micromirror Device%数字微镜器件用于光束空间整形

    Institute of Scientific and Technical Information of China (English)

    黄大杰; 范薇; 林尊琪

    2011-01-01

    The operating principle of digital micromirror device (DMD) is introduced. When the titled angle of a pixel mirror is set at +12° or -12°, it means that the optical transmissivity of this pixel is 0 or 1. With the help of the design method in binary panels, error diffusion method is used to spatially shape the 1053 nm laser pulse, which also realizes an initiative way of spatial modulation for laser pulse. Filling factor (FF) and field modulation (FM) are both factors which decide the quality of the near field laser beam and they directly affect energy availability factor of the high power laser system. In this experiment, FF increases from 33% to 65% and FM decreases from 52% to 28% after being shaped, and the size of the shaped beam is the same as we expected. At the end, the energy availability factor and mirror stability of this DMD are tested.%介绍了数字微镜器件(DMD)的工作原理,当DMD某像素微镜的角度固定在+12°或-12°,其在光学上等价于控制该像素的透射率为O或1.结合二元面板的设计思想,用误差扩散法对DMD各像素微镜的状态进行设计,用以对1053 nm脉冲光进行空间整形,实现了一种主动、实时的光脉冲空间整形方案.填充因子(FF)和光场调制度(FM)作为评价光束近场质量的参数,在高功率激光系统中直接影响系统的能量利用率.上述实验中,经过空间整形,光束的填充因子由33% 提高为65%,光场调制度由52% 降为28%.而且整形后的光斑大小与预期相符.最后对实验所用的DMD进行了能量利用率、波前畸变稳定性的测试.

  17. Resolution enhancement using pulse width modulation in digital micromirror device-based point-array scanning pattern exposure

    Science.gov (United States)

    Kuo, Hung-Fei; Huang, Yi-Jun

    2016-04-01

    Digital-mask lithography systems, with a digital micromirror device (DMD) as their central piece, have been widely used for defining patterns on printed circuit board (PCB). This study designed optical module parameters for point-array projection lithography based on field tracing technique to improve the quality of the aerial image on the exposure plane. In the realized optical module for the point-array projection lithography, a DMD was used as the dynamic digital-mask, and a 405-nm-wavelength laser was used to illuminate the DMD. The laser was then focused through the micro-lens array in the optical module to form a point array and was projected onto a dynamic scanning stage. By calculating the beam-overlapping rate, stage velocity, spot diameter, and DMD frame rate and programming them into the stage- and DMD-synchronized controller, the point array formed line patterns on the photoresist. Furthermore, using pulse width modulation (PWM) technique to operate the activation periods of the DMD mirrors effectively controlled the exposure and achieved a feature linewidth of less than 10 μm.

  18. Experimental demonstration of electron longitudinal-phase-space linearization by shaping the photoinjector laser pulse.

    Science.gov (United States)

    Penco, G; Danailov, M; Demidovich, A; Allaria, E; De Ninno, G; Di Mitri, S; Fawley, W M; Ferrari, E; Giannessi, L; Trovó, M

    2014-01-31

    Control of the electron-beam longitudinal-phase-space distribution is of crucial importance in a number of accelerator applications, such as linac-driven free-electron lasers, colliders and energy recovery linacs. Some longitudinal-phase-space features produced by nonlinear electron beam self- fields, such as a quadratic energy chirp introduced by geometric longitudinal wakefields in radio-frequency (rf) accelerator structures, cannot be compensated by ordinary tuning of the linac rf phases nor corrected by a single high harmonic accelerating cavity. In this Letter we report an experimental demonstration of the removal of the quadratic energy chirp by properly shaping the electron beam current at the photoinjector. Specifically, a longitudinal ramp in the current distribution at the cathode linearizes the longitudinal wakefields in the downstream linac, resulting in a flat electron current and energy distribution. We present longitudinal-phase-space measurements in this novel configuration compared to those typically obtained without longitudinal current shaping at the FERMI linac.

  19. Effects of shape and size of agar gels on heating uniformity during pulsed microwave treatment.

    Science.gov (United States)

    Soto-Reyes, Nohemí; Temis-Pérez, Ana L; López-Malo, Aurelio; Rojas-Laguna, Roberto; Sosa-Morales, María Elena

    2015-05-01

    Model gel systems with different shape (sphere, cylinder, and slab) and size (180 and 290 g) were prepared with agar (5%) and sucrose (5%). Dielectric constant (ε'), loss factor (ε"), thermophysical properties, and temperature distribution of the model system were measured. Each agar model system was immersed and suspended in water, and then, heated in a microwave oven with intermittent heating until the core temperature reached 50 °C. The ε' and ε" of agar gels decreased when frequency increased. The density and thermal conductivity values of the agar gels were 1033 kg/m(3) and 0.55 W/m °C, respectively. The temperature distribution of sphere, cylinder, and slab was different when similar power doses were applied. The slab reached 50 °C in less time (10 min) and showed a more uniform heating than spheres and cylinders in both sizes. Agar model systems of 180 g heated faster than those of 290 g. The coldest point was the center of the model systems in all studied cases. Shape and size are critical food factors that affect the heating uniformity during microwave heating processes.

  20. Measurement of the scintillation time spectra and pulse-shape discrimination of low-energy β and nuclear recoils in liquid argon with DEAP-1

    Science.gov (United States)

    Amaudruz, P.-A.; Batygov, M.; Beltran, B.; Bonatt, J.; Boudjemline, K.; Boulay, M. G.; Broerman, B.; Bueno, J. F.; Butcher, A.; Cai, B.; Caldwell, T.; Chen, M.; Chouinard, R.; Cleveland, B. T.; Cranshaw, D.; Dering, K.; Duncan, F.; Fatemighomi, N.; Ford, R.; Gagnon, R.; Giampa, P.; Giuliani, F.; Gold, M.; Golovko, V. V.; Gorel, P.; Grace, E.; Graham, K.; Grant, D. R.; Hakobyan, R.; Hallin, A. L.; Hamstra, M.; Harvey, P.; Hearns, C.; Hofgartner, J.; Jillings, C. J.; Kuźniak, M.; Lawson, I.; La Zia, F.; Li, O.; Lidgard, J. J.; Liimatainen, P.; Lippincott, W. H.; Mathew, R.; McDonald, A. B.; McElroy, T.; McFarlane, K.; McKinsey, D. N.; Mehdiyev, R.; Monroe, J.; Muir, A.; Nantais, C.; Nicolics, K.; Nikkel, J.; Noble, A. J.; O'Dwyer, E.; Olsen, K.; Ouellet, C.; Pasuthip, P.; Peeters, S. J. M.; Pollmann, T.; Rau, W.; Retière, F.; Ronquest, M.; Seeburn, N.; Skensved, P.; Smith, B.; Sonley, T.; Tang, J.; Vázquez-Jáuregui, E.; Veloce, L.; Walding, J.; Ward, M.

    2016-12-01

    The DEAP-1 low-background liquid argon detector was used to measure scintillation pulse shapes of electron and nuclear recoil events and to demonstrate the feasibility of pulse-shape discrimination down to an electron-equivalent energy of 20 keVee. In the surface dataset using a triple-coincidence tag we found the fraction of β events that are misidentified as nuclear recoils to be cross-section sensitivity of 10-46 cm2, assuming negligible contribution from nuclear recoil backgrounds.

  1. Measurement of Scintillation and Ionization Yield and Scintillation Pulse Shape from Nuclear Recoils in Liquid Argon

    CERN Document Server

    Cao, H; Avetisyan, R; Back, H O; Cocco, A G; DeJongh, F; Fiorillo, G; Galbiati, C; Grandi, L; Guardincerri, Y; Kendziora, C; Lippincott, W H; Love, C; Lyons, S; Manenti, L; Martoff, C J; Meng, Y; Montanari, D; Mosteiro, P; Olvitt, D; Pordes, S; Qian, H; Rossi, B; Saldanha, R; Sangiorgio, S; Siegl, K; Strauss, S Y; Tan, W; Tatarowicz, J; Walker, S; Wang, H; Watson, A W; Westerdale, S; Yoo, J

    2014-01-01

    We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase Liquid Argon Time Projection Chamber (LAr-TPC) to a low energy pulsed narrowband neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We report measurements of the scintillation and ionization yields for nuclear recoils with energies from 10.3 to 57.2 keV and for applied electric fields from 0 to 1000 V/cm. We also report the observation of an anti-correlation between scintillation and ionization from nuclear recoils, which is similar to the anti-correlation between scintillation and ionization from electron recoils. A comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field yielded a first evidence of sensitivity to direct...

  2. 3D shape measurement of macroscopic objects in digital off-axis holography using structured illumination.

    Science.gov (United States)

    Grosse, Marcus; Buehl, Johannes; Babovsky, Holger; Kiessling, Armin; Kowarschik, Richard

    2010-04-15

    We propose what we believe to be a novel approach to measure the 3D shape of arbitrary diffuse-reflecting macroscopic objects in holographic setups. Using a standard holographic setup, a second CCD and a liquid-crystal-on-silicon spatial light modulator to modulate the object wave, the method yields a dense 3D point cloud of an object or a scene. The calibration process is presented, and first quantitative results of a shape measurement are shown and discussed. Furthermore, a shape measurement of a complex object is displayed to demonstrate its universal use.

  3. Electronic regulation of the SPS extraction quadrupole current pulse shape for improved stability of the extracted beam

    CERN Document Server

    Carlier, E; Vossenberg, Eugène B; CERN. Geneva. SPS and LEP Division

    1996-01-01

    In order to minimise the event pile-up and therefore optimise the detection efficiency, Chorus and Nomad experiments ask for a long and rectangular spill profile. At present the fast-slow extractio n is generated by driving the beam into a quadrupolar-octopolar resonance by exciting a quadrupole magnet with a semi-trapezoidal current [1]. The trapezoidal pulse shape is obtained by dischargin g a capacitor into the magnet coils. After a few milliseconds of undamped discharge a fixed resistor is switched into the circuit. The attenuation is then higher and the sine wave continues with a lower gradient. The two gradients can be adjusted by varying the initial capacitor voltage and the time at which the resistor is switched into the circuit. A further degree of freedom in determini ng the spill shape has been added by allowing the possibility of changing the second slope value independently of the initial conditions. This task is achieved by means of a variable current sour ce added in parallel to the fixed resis...

  4. Measurement of scintillation and ionization yield and scintillation pulse shape from nuclear recoils in liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Cao, H.; Alexander, T.; Aprahamian, A.; Avetisyan, R.; Back, H. O.; Cocco, A. G.; DeJongh, F.; Fiorillo, G.; Galbiati, C.; Grandi, L.; Guardincerri, Y.; Kendziora, C.; Lippincott, W. H.; Love, C.; Lyons, S.; Manenti, L.; Martoff, C. J.; Meng, Y.; Montanari, D.; Mosteiro, P.; Olvitt, D.; Pordes, S.; Qian, H.; Rossi, B.; Saldanha, R.; Sangiorgio, S.; Siegl, K.; Strauss, S. Y.; Tan, W.; Tatarowicz, J.; Walker, S.; Wang, H.; Watson, A. W.; Westerdale, S.; Yoo, J.

    2015-05-01

    We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0 to 970 V / cm . For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V / cm . We also report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils. Assuming that the energy loss partitions into excitons and ion pairs from 83 m Kr internal conversion electrons is comparable to that from 207 Bi conversion electrons, we obtained the numbers of excitons ( N ex ) and ion pairs ( N i ) and their ratio ( N ex / N i ) produced by nuclear recoils from 16.9 to 57.3 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.

  5. Digitization

    DEFF Research Database (Denmark)

    Finnemann, Niels Ole

    2014-01-01

    Processes of digitization have for years represented a major trend in the developments of modern society but have only recently been related to processes of mediatization. The purpose of this article is to look into the relation between the concepts of mediatization and digitization and to clarify...... what a concept of digital media might add to the understanding of processes of mediatization and what the concept of mediatization might add to the understanding of digital media. It is argued that digital media open an array of new trajectories in human communication, trajectories which were...... not anticipated in previous conceptualizations of media and mediatization. If digital media are to be included, the concept of mediatization has to be revised and new parameters are to be built into the concept of media. At the same time it is argued that the concept of mediatization still provides a variety...

  6. Improved grid-noise removal in single-frame digital moiré 3D shape measurement

    Science.gov (United States)

    Mohammadi, Fatemeh; Kofman, Jonathan

    2016-11-01

    A single-frame grid-noise removal technique was developed for application in single-frame digital-moiré 3D shape measurement. The ability of the stationary wavelet transform (SWT) to prevent oscillation artifacts near discontinuities, and the ability of the Fourier transform (FFT) applied to wavelet coefficients to separate grid-noise from useful image information, were combined in a new technique, SWT-FFT, to remove grid-noise from moiré-pattern images generated by digital moiré. In comparison to previous grid-noise removal techniques in moiré, SWT-FFT avoids the requirement for mechanical translation of optical components and capture of multiple frames, to enable single-frame moiré-based measurement. Experiments using FFT, Discrete Wavelet Transform (DWT), DWT-FFT, and SWT-FFT were performed on moiré-pattern images containing grid noise, generated by digital moiré, for several test objects. SWT-FFT had the best performance in removing high-frequency grid-noise, both straight and curved lines, minimizing artifacts, and preserving the moiré pattern without blurring and degradation. SWT-FFT also had the lowest noise amplitude in the reconstructed height and lowest roughness index for all test objects, indicating best grid-noise removal in comparison to the other techniques.

  7. Hydrogenated amorphous silicon p-i-n solar cells deposited under well controlled ion bombardment using pulse-shaped substrate biasing

    NARCIS (Netherlands)

    Wank, M. A.; van Swaaij, R.; R. van de Sanden,; Zeman, M.

    2012-01-01

    We applied pulse-shaped biasing (PSB) to the expanding thermal plasma deposition of intrinsic hydrogenated amorphous silicon layers at substrate temperatures of 200 degrees C and growth rates of about 1?nm/s. Fourier transform infrared spectroscopy of intrinsic films showed a densification with incr

  8. Power pulsing scheme for analog and digital electronics of the vertex detectors at CLIC

    CERN Document Server

    Blanchot, Georges

    2015-01-01

    The precision requirements of the vertex detector at CLIC impose strong limitations on the mass of such a detector (< 0.2% of a radiation length, Xo, per layer). To achieve such a low material budget, ultra-thin hybrid pixel detectors are foreseen, while the mass for cooling and services will be reduced by implementing a power pulsing scheme that takes advantage of the low duty cycle of the accelerator. The principal aim is to achieve significant power reduction without compromising the power integrity supplied to the front-end electronics. This report summarises the study of a power pulsing scheme to power the vertex barrel electronics of the future CLIC experiment. Its main goal is to describe in more detail what has been already presented in TWEPP conferences and other presentations. The report can therefore serve as an operator manual for future use and development of the system

  9. Segmenting multiple overlapping objects via a hybrid active contour model incorporating shape priors: applications to digital pathology

    Science.gov (United States)

    Ali, Sahirzeeshan; Madabhushi, Anant

    2011-03-01

    Active contours and active shape models (ASM) have been widely employed in image segmentation. A major limitation of active contours, however, is in their (a) inability to resolve boundaries of intersecting objects and to (b) handle occlusion. Multiple overlapping objects are typically segmented out as a single object. On the other hand, ASMs are limited by point correspondence issues since object landmarks need to be identified across multiple objects for initial object alignment. ASMs are also are constrained in that they can usually only segment a single object in an image. In this paper, we present a novel synergistic boundary and region-based active contour model that incorporates shape priors in a level set formulation. We demonstrate an application of these synergistic active contour models using multiple level sets to segment nuclear and glandular structures on digitized histopathology images of breast and prostate biopsy specimens. Unlike previous related approaches, our model is able to resolve object overlap and separate occluded boundaries of multiple objects simultaneously. The energy functional of the active contour is comprised of three terms. The first term comprises the prior shape term, modeled on the object of interest, thereby constraining the deformation achievable by the active contour. The second term, a boundary based term detects object boundaries from image gradients. The third term drives the shape prior and the contour towards the object boundary based on region statistics. The results of qualitative and quantitative evaluation on 100 prostate and 14 breast cancer histology images for the task of detecting and segmenting nuclei, lymphocytes, and glands reveals that the model easily outperforms two state of the art segmentation schemes (Geodesic Active Contour (GAC) and Roussons shape based model) and resolves up to 92% of overlapping/occluded lymphocytes and nuclei on prostate and breast cancer histology images.

  10. Robust 9-QAM digital recovery for spectrum shaped coherent QPSK signal

    DEFF Research Database (Denmark)

    Huang, Bo; Zhang, Junwen; Yu, Jianjun

    2013-01-01

    is used for 9-QAM recovery and intersymbol interference (ISI) compression. It shows the robustness under strong filtering to recover 9-QAM signal rather than QPSK. We demonstrate 112 Gb/s spectrum shaped PM-QPSK signal by wavelength selective switch (WSS) in a 25-GHz channel spacing Nyquist wavelength...

  11. Alpha-gamma discrimination by pulse shape in LaBr{sub 3}:Ce and LaCl{sub 3}:Ce

    Energy Technology Data Exchange (ETDEWEB)

    Crespi, F.C.L. [Universita di Milano, Dipartimento di Fisica, Via Celoria 16, 20133 Milano (Italy); INFN sez. of Milano Via Celoria 16, 20133 Milano (Italy); Camera, F. [Universita di Milano, Dipartimento di Fisica, Via Celoria 16, 20133 Milano (Italy); INFN sez. of Milano Via Celoria 16, 20133 Milano (Italy)], E-mail: camera@mi.infn.it; Blasi, N. [INFN sez. of Milano Via Celoria 16, 20133 Milano (Italy); Bracco, A. [Universita di Milano, Dipartimento di Fisica, Via Celoria 16, 20133 Milano (Italy); INFN sez. of Milano Via Celoria 16, 20133 Milano (Italy); Brambilla, S.; Million, B. [INFN sez. of Milano Via Celoria 16, 20133 Milano (Italy); Nicolini, R. [Universita di Milano, Dipartimento di Fisica, Via Celoria 16, 20133 Milano (Italy); INFN sez. of Milano Via Celoria 16, 20133 Milano (Italy); Pellegri, L. [Universita di Milano, Dipartimento di Fisica, Via Celoria 16, 20133 Milano (Italy); Riboldi, S.; Sassi, M. [Universita di Milano, Dipartimento di Fisica, Via Celoria 16, 20133 Milano (Italy); INFN sez. of Milano Via Celoria 16, 20133 Milano (Italy); Wieland, O. [INFN sez. of Milano Via Celoria 16, 20133 Milano (Italy); Quarati, F.; Owens, A. [Advanced Studies and Technology Preparation Division (SCI-PA), ESA/ESTEC Keplerlaan 1, 2201AZ Noordwijk (Netherlands)

    2009-04-21

    The line-shape of the signals from LaBr{sub 3}:Ce and LaCl{sub 3}:Ce detectors coupled to PM tubes were studied. The possibility of discriminating the type of interacting radiation was investigated making use of Pulse Shape Analysis (PSA) techniques. The study was performed measuring the self-activity present in lanthanum halide crystals in coincidence with {gamma}-rays in a HPGe crystal. A small but significant difference between {alpha}- and {gamma}-induced signals was directly observed for both the crystals. Using a simple PSA algorithm, it was possible to emphasize the differences in the pulse shape of {gamma}-rays and {alpha}-particles. This resulted in a rather clear identification of these two types of radiations.

  12. The combination of digital surface scanners and cone beam computed tomography technology for guided implant surgery using 3Shape implant studio software: a case history report.

    Science.gov (United States)

    Lanis, Alejandro; Álvarez Del Canto, Orlando

    2015-01-01

    The incorporation of virtual engineering into dentistry and the digitization of information are providing new perspectives and innovative alternatives for dental treatment modalities. The use of digital surface scanners with surgical planning software allows for the combination of the radiographic, prosthetic, surgical, and laboratory fields under a common virtual scenario, permitting complete digital treatment planning. In this article, the authors present a clinical case in which a guided implant surgery was performed based on a complete digital surgical plan combining the information from a cone beam computed tomography scan and the virtual simulation obtained from the 3Shape TRIOS intraoral surface scanner. The information was imported to and combined in the 3Shape Implant Studio software for guided implant surgery planning. A surgical guide was obtained by a 3D printer, and the surgical procedure was done using the Biohorizons Guided Surgery Kit and its protocol.

  13. Metal release in a stainless steel Pulsed Electric Field (PEF) system Part I. Effect of different pulse shapes; theory and experimental method

    NARCIS (Netherlands)

    Roodenburg, B.; Morren, J.; Berg, H.E.; Haan, S.W.H.de

    2005-01-01

    Liquid pumpable food is mostly pasteurised by heat treatment. In the last decennia there is an increasing interest in so-called Pulsed Electric Field (PEF) treatment. During this treatment food is pumped between two metal electrodes and exposed to short high electric field pulses, typical 2-4 kV mm-

  14. The experimental cascade curves of EAS at E sub 0 10(17) eV obtained by the method of detection of Cherenkov pulse shape

    Science.gov (United States)

    Fomin, Y. A.; Kalmykov, G. B.; Khristiansen, M. V.; Motova, M. V.; Nechin, Y. A.; Prosin, V. V.; Zhukov, V. Y.; Efimov, N. N.; Grigoriev, V. M.; Nikiforova, E. S.

    1985-01-01

    The individual cascade curves of EAS with E sub 0 10 to the 17th power eV/I to 3/ were studied by detection of EAS Cherenkov light pulses. The scintillators located at the center of the Yakutsk EAS array within a 500-m radius circle were used to select the showers and to determine the main EAS parameters. The individual cascade curves N(t) were obtained using the EAS Cherenkov light pulses satisfying the following requirements: (1) the signal-to-noise ratio fm/delta sub n 15, (2) the EAS axis-detector distance tau sub 350 m, (3) the zenith angle theta 30 deg, (4) the probability for EAS to be detected by scintillators W 0.8. Condition (1) arises from the desire to reduce the amplitude distortion of Cherenkov pulses due to noise and determines the range of EAS sizes, N(t). The resolution times of the Cherenkov pulse shape detectors are tau sub 0 approx. 23 ns which results in distortion of a pulse during the process of the detection. The distortion of pulses due to the finiteness of tau sub 0 value was estimated. It is shown that the rise time of pulse becomes greater as tau sub 0.5/tau sub 0 ratio decreases.

  15. Coherent control of atoms and diatomic molecules with shaped ultrashort pulses; Manipulation coherente d'atomes et de molecules diatomiques avec des impulsions mises en forme

    Energy Technology Data Exchange (ETDEWEB)

    Degert, J

    2002-12-15

    This thesis deals with the theoretical and experimental study of coherent control of atomic and molecular systems with shaped pulses. At first, we present several experiments of control of coherent transients in rubidium. These transients appear when a two-level system is excited by a perturbative chirped pulse, and are characterized by oscillations in the excited state population. For a strong chirp, we show that a phase step in the spectrum modifies the phase of the oscillations. Then, by direct analogy with Fresnel zone lens, we conceive a chirped pulse with a highly modulated amplitude, allowing to suppress destructive contributions to the population transfer. In a second set of experiments, we focus on quantum path interferences in two-photon transitions excited by linearly chirped pulses. Owing to the broad bandwidth of ultrashort pulses, sequential and direct excitation paths contribute to the excited state population. Oscillations resulting from interferences between these two paths are observed in atomic sodium. Moreover, we show that they are observable whatever the sign of chirp. Theoretically, we study the control of the predissociation of a benchmark diatomic molecule: NaI. Predissociation leads to matter wave interferences in the fragments distribution. First, we show that a suitably chosen probe pulse allows the observation of theses interferences. Next, using a sequence of control pulse inducing electronic transition, we demonstrate the possibility to manipulate fragment energy distribution. (author)

  16. Study on welding power source used in intelligent control system for weld pool shape in pulsed GTAW

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper analyses the performance request of arc welding power source used in intelligent control of weld pool shape in pulsed GTAW, and develops a sample power source. The main circuit of the power source takes the structure of single ended inverter with two switches, and takes IGBTs as power switches. The working frequency of the inverter is set at 20(¨)kHz. The control circuit takes PWM circuit as center, and uses single chip computer to complete the manage functions such as the control of working sequence, setting and changing of the welding parameters, sensing of the welding states and communication with outside computer etc. The dynamic reacting time of the whole power is 1(¨)ms, the range of the output current is 5~250(¨)A, the precision of the output current reaches to 1 A. The power strikes arc by contacting workpiece under 5A, and have convenient interface with system computer. All above shows this power source is one with high performance.

  17. Large field-induced irreversibility in Ni-Mn based Heusler shape-memory alloys: A pulsed magnetic field study

    Science.gov (United States)

    Nayak, A. K.; Mejia, C. Salazar; D'Souza, S. W.; Chadov, S.; Skourski, Y.; Felser, C.; Nicklas, M.

    2014-12-01

    We present a pulsed magnetic field study on the magnetic and magnetostriction properties of Ni-Mn-Z (Z =In , Sn, and Sb) based Heusler shape-memory alloys. These materials generally display a field-induced magnetostructural transition that could lead to an irreversible phase transition, when measured near the martensitic transition temperature. Here, we show that independently of the transition temperature, the critical field for the phase transition sensitively depends on the main-group element in the sample. Irrespective of their compositions, all samples display a magnetization of around 2 μB/f .u . in the martensite phase and about 6 μB/f .u . in the cubic austenite phase. Our magnetic and magnetostriction measurements at low temperatures exhibit a partial or complete arrest of the high-field austenite phase below the reverse martensitic transition. This results in a large irreversibility with a hysteresis width as high as 24 T. We introduce a theoretical model to discuss the experimental results.

  18. Digital Image Watermarking for Arbitrarily Shaped Objects Based On SA-DWT

    CERN Document Server

    Essaouabi, A; Fegragui, F

    2009-01-01

    Many image watermarking schemes have been proposed in recent years, but they usually involve embedding a watermark to the entire image without considering only a particular object in the image, which the image owner may be interested in. This paper proposes a watermarking scheme that can embed a watermark to an arbitrarily shaped object in an image. Before embedding, the image owner specifies an object of arbitrary shape that is of a concern to him. Then the object is transformed into the wavelet domain using in place lifting shape adaptive DWT(SADWT) and a watermark is embedded by modifying the wavelet coefficients. In order to make the watermark robust and transparent, the watermark is embedded in the average of wavelet blocks using the visual model based on the human visual system. Wavelet coefficients n least significant bits (LSBs) are adjusted in concert with the average. Simulation results shows that the proposed watermarking scheme is perceptually invisible and robust against many attacks such as loss...

  19. Digital Image Watermarking for Arbitrarily Shaped Objects Based On SA-DWT

    Directory of Open Access Journals (Sweden)

    F. Regragui

    2009-10-01

    Full Text Available Many image watermarking schemes have been proposed in recent years, but they usually involve embedding a watermark to the entire image without considering only a particular object in the image, which the image owner may be interested in. This paper proposes a watermarking scheme that can embed a watermark to an arbitrarily shaped object in an image. Before embedding, the image owner specifies an object of arbitrary shape that is of a concern to him. Then the object is transformed into the wavelet domain using in place lifting shape adaptive DWT(SADWT and a watermark is embedded by modifying the wavelet coefficients. In order to make the watermark robust and transparent, the watermark is embedded in the average of wavelet blocks using the visual model based on the human visual system. Wavelet coefficients n least significant bits (LSBs are adjusted in concert with the average. Simulation results shows that the proposed watermarking scheme is perceptually invisible and robust against many attacks such as lossy compression (e.g. JPEG, JPEG2000, scaling, adding noise, filtering, etc.

  20. Analysis of PMD and PDL effect on Chirped Gaussian and SuperGaussain pulse shapes by controlling SOP in SMF

    Directory of Open Access Journals (Sweden)

    VINAYAGAPRIYA.S

    2014-05-01

    Full Text Available In this paper, a numerical analysis of impairments due to PMD and PDL on system performance is investigated in High Speed Optical Communication System. Optical Polarization has pronounced effect on signal quality. Thus there is a need to control the State of Polarization (SOP. Pulse Broadening can be controlled by launching the light signal in particular State of Polarization such as Linear and Circular. Two types of Pulses such as Chirped Gaussian and Supergaussian pulses are launched at different SOP into the optical fiber and it is found that maximum pulse width reduction is achieved when the pulse is at Circular SOP than that of Linear SOP. Also results clearly show that with PMD and PDL, pulse width ratio of Chirped Gaussian pulse is much reduced than that of Chirped Supergaussian Pulse.

  1. Validation of Shape Context Based Image Registration Method Using Digital Image Correlation Measurement on a Rat Stomach

    DEFF Research Database (Denmark)

    Liao, Donghua; Wang, P; Zhao, Jingbo

    2014-01-01

    Recently we developed analysis for 3D visceral organ deformation by combining the shape context (SC) method with a full-field strain (strain distribution on a whole 3D surface) analysis for calculating distension-induced rat stomach deformation. The surface deformation detected by the SC method...... needs to be further verified by using a feature tracking measurement. Hence, the aim of this study was to verify the SC method-based calculation by using digital image correlation (DIC) measurement on a rat stomach. The rat stomach exposed to distension pressures 0.0, 0.2, 0.4, and 0.6 kPa were studied...... using both 3D DIC system and SC-based image registration calculation. Three different surface sample counts between the reference and the target surfaces were usedto gauge the effect of the surface sample counts on the calculation. Each pair of the surface points between the DIC measured target surface...

  2. Pulse shape discrimination of Cs2LiYCl6:Ce3+ detectors at high count rate based on triangular and trapezoidal filters

    Science.gov (United States)

    Wen, Xianfei; Enqvist, Andreas

    2017-09-01

    Cs2LiYCl6:Ce3+ (CLYC) detectors have demonstrated the capability to simultaneously detect γ-rays and thermal and fast neutrons with medium energy resolution, reasonable detection efficiency, and substantially high pulse shape discrimination performance. A disadvantage of CLYC detectors is the long scintillation decay times, which causes pulse pile-up at moderate input count rate. Pulse processing algorithms were developed based on triangular and trapezoidal filters to discriminate between neutrons and γ-rays at high count rate. The algorithms were first tested using low-rate data. They exhibit a pulse-shape discrimination performance comparable to that of the charge comparison method, at low rate. Then, they were evaluated at high count rate. Neutrons and γ-rays were adequately identified with high throughput at rates of up to 375 kcps. The algorithm developed using the triangular filter exhibits discrimination capability marginally higher than that of the trapezoidal filter based algorithm irrespective of low or high rate. The algorithms exhibit low computational complexity and are executable on an FPGA in real-time. They are also suitable for application to other radiation detectors whose pulses are piled-up at high rate owing to long scintillation decay times.

  3. Influence of the crash pulse shape on the peak loading and the injury tolerance levels of the neck in in vitro low-speed side-collisions.

    Science.gov (United States)

    Kettler, Annette; Fruth, Kai; Claes, Lutz; Wilke, Hans-Joachim

    2006-01-01

    The aim of the present in vitro study was to investigate the effect of the crash pulse shape on the peak loading and the injury tolerance levels of the human neck. In a custom-made acceleration apparatus 12 human cadaveric cervical spine specimens, equipped with a dummy head, were subjected to a series of incremental side accelerations. While the duration of the acceleration pulse of the sled was kept constant at 120 ms, its shape was varied: Six specimens were loaded with a slowly increasing pulse, i.e. a low loading rate, the other six specimens with a fast increasing pulse, i.e. a high loading rate. The loading of the neck was quantified in terms of the peak linear and angular acceleration of the head, the peak shear force and bending moment of the lower neck and the peak translation between head and sled. The shape of the acceleration curve of the sled only seemed to influence the peak translation between head and sled but none of the other four parameters. The neck injury tolerance level for the angular acceleration of the head and for the bending moment of the lower neck was almost identical for both, the high and the low loading rate. In contrast, the injury tolerance level for the linear acceleration of the head and for the shear force of the lower neck was slightly higher for the low loading rate as compared to the high loading rate. For the translation between head and sled this difference was even statistically significant. Thus, if the shape of the crash pulse is not known, solely the peak bending moment of the lower neck and the peak angular acceleration of the head seem to be suitable predictors for the neck injury risk but not the peak shear force of the lower neck, the peak linear acceleration of the head and the translation between head and thorax.

  4. A novel 2nd-order shape function based digital image correlation method for large deformation measurements

    Science.gov (United States)

    Bai, Ruixiang; Jiang, Hao; Lei, Zhenkun; Li, Weikang

    2017-03-01

    Compared with the traditional forward compositional matching strategy, the inverse compositional matching strategy has almost the same accuracy, but has an obviously higher efficiency than the former in digital image correlation (DIC) algorithms. Based on the inverse compositional matching strategy and the auxiliary displacement functions, a more accurate inverse compositional Gauss-Newton (IC-GN2) algorithm with a new second-order shape operator is proposed for nonuniform and large deformation measurements. A theoretical deduction showed that the new proposed second-order shape operator is invertible and can steadily attain second-order precision. The result of the numerical simulation showed that the matching accuracy of the new IC-GN2 algorithm is the same as that of the forward compositional Gauss-Newton (FC-GN2) algorithm and is relatively better than in IC-GN2 algorithm. Finally, a rubber tension experiment with a large deformation of 27% was performed to validate the feasibility of the proposed algorithm.

  5. New drive converter and digital control for the pulsed power supply system of ASDEX Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Käsemann, Claus-Peter, E-mail: c.p.kaesemann@ipp.mpg.de [Max Planck Institute for Plasma Physics, Boltzmannstraße 2, 85748 Garching (Germany); Jacob, Christian; Nguyen, Hong Ha; Stobbe, Ferdinand; Mayer, Alois [Max Planck Institute for Plasma Physics, Boltzmannstraße 2, 85748 Garching (Germany); Sachs, Edgar; Klein, Reiner [Siemens AG, Industrial Automation Systems, Gleiwitzer Straße 555, 90475 Nürnberg (Germany)

    2015-10-15

    Highlights: • IGBT converter system with integrated control. • Proven technology reduces time and budget. • Flexibility to be integrated into a 35 years old installation. • Stable control algorithms for static and dynamic speed control. • Possibilities for active and reactive power management. - Abstract: Safety and reliability are major issues for the ASDEX Upgrade (AUG) pulsed power supply systems. To avoid long downtimes during an experimental campaign, fault-prone components have to be identified and treated early. This becomes even more important due to the AUG participation in the EUROfusion Medium Sized Tokamak (MST) program. Operating equipment which is up to 40 years old adds additional complications. This contribution describes one such example where a 35 year old flywheel generator at AUG was identified as fault-prone and pre-emptively upgraded with a new drive converter with integrated control. Most challenging was to adapt a modern converter, originally designed for wind turbines, toward a drive system for a flywheel-motor-generator system. To identify the layout of the controller and the control parameters, accurate modeling and comprehensive simulations were performed. This effort paid off during commissioning and measuring results verified the calculated design values. Finally, the system shows good performance during AUG plasma experiments.

  6. A micropower supervisor for wireless nodes with a digital pulse frequency modulator battery monitor

    Science.gov (United States)

    Carloni, Mirko; d'Aparo, Rocco; Scorrano, Pierpaolo; Naticchia, Berardo; Conti, Massimo

    2013-05-01

    In the last few years the increased development of wireless technologies led to the development of micropower devices with power management and real time power control, aimed to maximize the battery life time.1 The main and simplest method to estimate residual battery life time is by voltage measurement. This kind of measurement is simple but is useless in many cases, especially when long term Lithium-Thionyl chloride batteries are used, since its voltage is flat for more than 90% of the battery discharge. In this case, a current control should be used. However, these kinds of devices have various problems as a limited range of measurement and not negligible quiescent current that may distort the measurements. In this work we developed a micropower supervisor for wireless sensor nodes with a charge battery monitor, whose features are aimed at solving the problems just described. The current measured by a sense resistor, is filtered by a super-capacitor, amplified by a current sense amplifier and then fed to a voltage to pulse frequency modulator. In this way, the charge consumption can be estimated without the saturation of the current sense amplifier, even if the wireless node consumes time limited high current spikes, for example during transmission.

  7. Paediatric pelvic imaging: optimisation of dose and technique using digital grid-controlled pulsed fluoroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Waugh, R.; McCarty, M. [Div. of Radiology, South Cleveland Hospital, South Tees Acute Hospitals NHS Trust, Marton Road, Middlesbrough, Cleveland (United Kingdom); McCallum, H.M. [Regional Medical Physics Dept., South Cleveland Hospital, Middlesbrough (United Kingdom); Montgomery, R. [Dept. of Orthopaedics, South Tees Hospitals NITS Trust, Middlesbrough (United Kingdom); Aszkenasy, M. [Tees and North East Yorkshire NHS Trust, West Lane Hospital, Middlesbrough (United Kingdom)

    2001-05-01

    Background. An audit of paediatric pelvic radiographs identified deficiencies in gonad shield placement and radiographic technique. Objective. A technique using grid-controlled fluoroscopy (GCF), with hard copy images in frame grab and digital spot image (DSI) format was evaluated to optimise gonad shield placement and reduce the dose given to children with Perthes disease and Developmental Hip Dysplasia (DDH) attending for pelvic radiography. Materials and methods. Phantom and patient dose surveys of conventional and fluoroscopic techniques were carried out. Image quality and radiation dose were compared for the frame grab and DSI techniques. Retrospective evaluation was undertaken to compare their clinical acceptability. Results. Both fluoroscopic techniques gave considerably less radiation than conventional non-grid radiography (67-83 %, P < 0.05). The frame grab technique gave less radiation than DSI (P < 0.05). There was no significant difference in the clinical acceptability scores of the DSI and frame grab images. Conclusion. Fluoroscopy acquired images are now used since the fluoroscopic techniques give much less dose than conventional radiography and provide images of sufficient quality for clinical assessment. Indeed, as there was no significant difference in clinical usefulness between the frame grab and DSI techniques, it is planned to use frame grab alone, thus gaining additional dose saving. (orig.)

  8. Digital Morphing Wing: Active Wing Shaping Concept Using Composite Lattice-Based Cellular Structures

    Science.gov (United States)

    Jenett, Benjamin; Calisch, Sam; Cellucci, Daniel; Cramer, Nick; Gershenfeld, Neil; Swei, Sean

    2017-01-01

    Abstract We describe an approach for the discrete and reversible assembly of tunable and actively deformable structures using modular building block parts for robotic applications. The primary technical challenge addressed by this work is the use of this method to design and fabricate low density, highly compliant robotic structures with spatially tuned stiffness. This approach offers a number of potential advantages over more conventional methods for constructing compliant robots. The discrete assembly reduces manufacturing complexity, as relatively simple parts can be batch-produced and joined to make complex structures. Global mechanical properties can be tuned based on sub-part ordering and geometry, because local stiffness and density can be independently set to a wide range of values and varied spatially. The structure's intrinsic modularity can significantly simplify analysis and simulation. Simple analytical models for the behavior of each building block type can be calibrated with empirical testing and synthesized into a highly accurate and computationally efficient model of the full compliant system. As a case study, we describe a modular and reversibly assembled wing that performs continuous span-wise twist deformation. It exhibits high performance aerodynamic characteristics, is lightweight and simple to fabricate and repair. The wing is constructed from discrete lattice elements, wherein the geometric and mechanical attributes of the building blocks determine the global mechanical properties of the wing. We describe the mechanical design and structural performance of the digital morphing wing, including their relationship to wind tunnel tests that suggest the ability to increase roll efficiency compared to a conventional rigid aileron system. We focus here on describing the approach to design, modeling, and construction as a generalizable approach for robotics that require very lightweight, tunable, and actively deformable structures. PMID:28289574

  9. Multiple One-Dimensional Search (MODS) algorithm for fast optimization of laser-matter interaction by phase-only fs-laser pulse shaping

    Science.gov (United States)

    Galvan-Sosa, M.; Portilla, J.; Hernandez-Rueda, J.; Siegel, J.; Moreno, L.; Solis, J.

    2014-09-01

    In this work, we have developed and implemented a powerful search strategy for optimization of nonlinear optical effects by means of femtosecond pulse shaping, based on topological concepts derived from quantum control theory. Our algorithm [Multiple One-Dimensional Search (MODS)] is based on deterministic optimization of a single solution rather than pseudo-random optimization of entire populations as done by commonly used evolutionary algorithms. We have tested MODS against a genetic algorithm in a nontrivial problem consisting in optimizing the Kerr gating signal (self-interaction) of a shaped laser pulse in a detuned Michelson interferometer configuration. The obtained results show that our search method (MODS) strongly outperforms the genetic algorithm in terms of both convergence speed and quality of the solution. These findings demonstrate the applicability of concepts of quantum control theory to nonlinear laser-matter interaction problems, even in the presence of significant experimental noise.

  10. 一种新结构U型脉冲管制冷机%A New Structural U-Shape Pulse Tube Cryocooler

    Institute of Scientific and Technical Information of China (English)

    尹传林; 陈厚磊; 蔡京辉

    2012-01-01

    在U型脉冲管制冷机结构基础上,研制了一台带有一个蓄冷器和两个相同脉管的新结构U型脉冲管制冷机,并进行了实验研究和分析。制冷机采用惯性管调相,在压缩机输入电功率80w,运行频率52Hz下,获得了120K@6W的制冷量。重点对两种惯性管调相方法进行研究和分析,得出了对新结构U型脉冲管制冷机调相有益的结论,并对惯性管调相过程中产生的直流现象进行了验证分析。%A new structural U-shape pulse tube cryocooler based on the U-shape pulse tube cryocooler, with one regenerator and the same two pulse tubes, has been designed and manufactured. The pulse cryocooler is able to gain 120 K@6 W cooling power with 80 W electric power at the operating frequency of 52 Hz. The method of the inertance tube phase-shifting is investigated and the useful conclusion is obtained for the pahse-shifting of new structural U-shape pulse tube cryocooler. The DC flow that occures in the inertance tube phase-shifting is also tested and analysed.

  11. Experimental Comparison of Gains in Achievable Information Rates from Probabilistic Shaping and Digital Backpropagation for DP-256QAM/1024QAM WDM Systems

    DEFF Research Database (Denmark)

    Porto da Silva, Edson; Yankov, Metodi Plamenov; Da Ros, Francesco;

    2016-01-01

    Gains in achievable information rates from probabilistic shaping and digital backpropagation are compared for WDM transmission of 5 × 10 GBd DP-256QAM/1024QAM up to 1700 km of reach. The combination of both techniques its shown to provide gains of up to ∼0.5 bits/QAM symbol...

  12. Dynamic feedback circuits function as a switch for shaping a maturation-inducing steroid pulse in Drosophila

    DEFF Research Database (Denmark)

    Møller, Morten Erik; Danielsen, Erik Thomas; Herder, Rachel;

    2013-01-01

    Steroid hormones trigger the onset of sexual maturation in animals by initiating genetic response programs that are determined by steroid pulse frequency, amplitude and duration. Although steroid pulses coordinate growth and timing of maturation during development, the mechanisms generating...... that functions in producing steroid oscillations that can guide the decision to terminate growth and promote maturation....... these pulses are not known. Here we show that the ecdysone steroid pulse that drives the juvenile-adult transition in Drosophila is determined by feedback circuits in the prothoracic gland (PG), the major steroid-producing tissue of insect larvae. These circuits coordinate the activation and repression...

  13. Differences between visual hemifields in identifying rapidly presented target stimuli: Letters and digits, faces, and shapes.

    Directory of Open Access Journals (Sweden)

    Dariusz eAsanowicz

    2013-07-01

    Full Text Available The right hemisphere has been shown to play a dominant role in processing of visuo-spatial information. Recently, this role has been studied in the two-stream rapid serial visual presentation task. In this task, two alphanumerical targets are embedded in left and right simultaneous streams of rapidly changing letters. The second target (T2 is identified better in the left than in the right visual field. This difference has been interpreted as advantage of the right hemisphere (RH. However, a disadvantage of the left hemisphere (LH could not be excluded so far. The LH, specialized for processing of verbal stimuli, might be overloaded due to constant input of letters from both visual fields. In the present study, this overload hypothesis was tested by reducing demands on verbal processing (Experiments 1, and by overloading the RH with nonverbal stimuli: faces (Experiment 2 and irregular shapes (Experiment 3. The left visual field advantage proved to be largely independent from the level of verbal load and from stimulus type. Therefore, although not entirely disproving the overload hypothesis, these results suggest as the most parsimonious explanation this asymmetry reflects a RH advantage, presumably in perceptual and attentional processing, rather than a LH disadvantage caused by verbal overload.

  14. Ultrahigh-resolution spectroscopy with atomic or molecular dark resonances: Exact steady-state line shapes and asymptotic profiles in the adiabatic pulsed regime

    Energy Technology Data Exchange (ETDEWEB)

    Zanon-Willette, Thomas; Clercq, Emeric de; Arimondo, Ennio [UPMC Univ. Paris 06, UMR 7092, LPMAA, 4 place Jussieu, case 76, F-75005 Paris, France, and CNRS, UMR 7092, LPMAA, 4 place Jussieu, case 76, F-75005 Paris (France); LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 61 avenue de l' Observatoire, F-75014 Paris (France); Dipartimento di Fisica ' ' E. Fermi,' ' Universita di Pisa, Lgo. B. Pontecorvo 3, I-56122 Pisa (Italy)

    2011-12-15

    Exact and asymptotic line shape expressions are derived from the semiclassical density matrix representation describing a set of closed three-level {Lambda} atomic or molecular states including decoherences, relaxation rates, and light shifts. An accurate analysis of the exact steady-state dark-resonance profile describing the Autler-Townes doublet, the electromagnetically induced transparency or coherent population trapping resonance, and the Fano-Feshbach line shape leads to the linewidth expression of the two-photon Raman transition and frequency shifts associated to the clock transition. From an adiabatic analysis of the dynamical optical Bloch equations in the weak field limit, a pumping time required to efficiently trap a large number of atoms into a coherent superposition of long-lived states is established. For a highly asymmetrical configuration with different decay channels, a strong two-photon resonance based on a lower states population inversion is established when the driving continuous-wave laser fields are greatly unbalanced. When time separated resonant two-photon pulses are applied in the adiabatic pulsed regime for atomic or molecular clock engineering, where the first pulse is long enough to reach a coherent steady-state preparation and the second pulse is very short to avoid repumping into a new dark state, dark-resonance fringes mixing continuous-wave line shape properties and coherent Ramsey oscillations are created. Those fringes allow interrogation schemes bypassing the power broadening effect. Frequency shifts affecting the central clock fringe computed from asymptotic profiles and related to the Raman decoherence process exhibit nonlinear shapes with the three-level observable used for quantum measurement. We point out that different observables experience different shifts on the lower-state clock transition.

  15. Breast mass segmentation in digital mammography based on pulse coupled neural network and level set method

    Science.gov (United States)

    Xie, Weiying; Ma, Yide; Li, Yunsong

    2015-05-01

    A novel approach to mammographic image segmentation, termed as PCNN-based level set algorithm, is presented in this paper. Just as its name implies, a method based on pulse coupled neural network (PCNN) in conjunction with the variational level set method for medical image segmentation. To date, little work has been done on detecting the initial zero level set contours based on PCNN algorithm for latterly level set evolution. When all the pixels of the input image are fired by PCNN, the small pixel value will be a much more refined segmentation. In mammographic image, the breast tumor presents big pixel value. Additionally, the mammographic image with predominantly dark region, so that we firstly obtain the negative of mammographic image with predominantly dark region except the breast tumor before all the pixels of an input image are fired by PCNN. Therefore, in here, PCNN algorithm is employed to achieve mammary-specific, initial mass contour detection. After that, the initial contours are all extracted. We define the extracted contours as the initial zero level set contours for automatic mass segmentation by variational level set in mammographic image analysis. What's more, a new proposed algorithm improves external energy of variational level set method in terms of mammographic images in low contrast. In accordance with the gray scale of mass region in mammographic image is higher than the region surrounded, so the Laplace operator is used to modify external energy, which could make the bright spot becoming much brighter than the surrounded pixels in the image. A preliminary evaluation of the proposed method performs on a known public database namely MIAS, rather than synthetic images. The experimental results demonstrate that our proposed approach can potentially obtain better masses detection results in terms of sensitivity and specificity. Ultimately, this algorithm could lead to increase both sensitivity and specificity of the physicians' interpretation of

  16. Packet error rate analysis of digital pulse interval modulation in intersatellite optical communication systems with diversified wavefront deformation.

    Science.gov (United States)

    Zhu, Jin; Wang, Dayan; Xie, Wanqing

    2015-02-20

    Diversified wavefront deformation is an inevitable phenomenon in intersatellite optical communication systems, which will decrease system performance. In this paper, we investigate the description of wavefront deformation and its influence on the packet error rate (PER) of digital pulse interval modulation (DPIM). With the wavelet method, the diversified wavefront deformation can be described by wavelet parameters: coefficient, dilation, and shift factors, where the coefficient factor represents the depth, dilation factor represents the area, and shift factor is for location. Based on this, the relationship between PER and wavelet parameters is analyzed from a theoretical viewpoint. Numerical results illustrate the validity of theoretical analysis: PER increases with the depth and area and decreases if location gets farther from the center of the optical antenna. In addition to describing diversified deformation, the advantage of the wavelet method over Zernike polynomials in computational complexity is shown via numerical example. This work provides a feasible method for the description along with influence analysis of diversified wavefront deformation from a practical viewpoint and will be helpful for designing optical systems.

  17. The long-term evolution of the spin, pulse shape, and orbit of the accretion-powered millisecond pulsar SAX J1808.4-3658

    CERN Document Server

    Hartman, Jacob M; Chakrabarty, Deepto; Kaplan, David L; Markwardt, Craig B; Morgan, Edward H; Ray, Paul S; van der Klis, Michiel; Wijnands, Rudy

    2007-01-01

    We present a 7 yr timing study of the 2.5 ms X-ray pulsar SAX J1808.4-3658, an X-ray transient with a recurrence time of ~2 yr, using data from the Rossi X-ray Timing Explorer covering 4 transient outbursts (1998-2005). We verify that the 401 Hz pulsation traces the spin frequency fundamental and not a harmonic. Substantial pulse shape variability, both stochastic and systematic, was observed during each outburst. Analysis of the systematic pulse shape changes suggests that, as an outburst dims, the X-ray "hot spot" on the pulsar surface drifts longitudinally and a second hot spot may appear. The overall pulse shape variability limits the ability to measure spin frequency evolution within a given X-ray outburst (and calls previous nudot measurements of this source into question), with typical upper limits of |nudot| < 2.5x10^{-14} Hz/s (2 sigma). However, combining data from all the outbursts shows with high (6 sigma) significance that the pulsar is undergoing long-term spin down at a rate nudot = (-5.6+/-...

  18. Power quality improvement by using multi-pulse AC-DC converters for DC drives: Modeling, simulation and its digital implementation

    Directory of Open Access Journals (Sweden)

    Mohd Tariq

    2014-12-01

    Full Text Available The paper presents the modeling, simulation and digital implementation of power quality improvement of DC drives by using multi pulse AC–DC converter. As it is a well-known fact that power quality determines the fitness of electrical power to consumer devices, hence an effort has been made to improve power quality in this work. Simulation and digital implementation with the help of MATLAB/Simulink has been done and results obtained are discussed in detail to verify the theoretical results. The multipulse converter was connected with DC drives and was run at no load condition to find out the transient and steady state performances. FFT analysis has been performed and Total Harmonic Distortion (THD results obtained at different pulses are shown here.

  19. In-Fiber Subpicosecond Pulse Shaping for Nonlinear Optical Telecommunication Data Processing at 640 Gbit/s

    DEFF Research Database (Denmark)

    Azaña, J.; Oxenløwe, Leif Katsuo; Palushani, Evarist

    2012-01-01

    -optic telecommunication links operating up to 640 Gbit/s. Experiments are presented demonstrating error-free 640-to-10 Gbit/s demultiplexing of the 64 tributary channels using the generated flat-top pulses for temporal gating in a Kerr-effect-based nonlinear optical loop mirror. The use of flat-top pulses has critical...

  20. Production rate enhancement of size-tunable silicon nanoparticles by temporally shaping femtosecond laser pulses in ethanol.

    Science.gov (United States)

    Li, Xin; Zhang, Guangming; Jiang, Lan; Shi, Xuesong; Zhang, Kaihu; Rong, Wenlong; Duan, Ji'an; Lu, Yongfeng

    2015-02-23

    This paper proposes an efficient approach for production-rate enhancement and size reduction of silicon nanoparticles produced by femtosecond (fs) double-pulse ablation of silicon in ethanol. Compared with a single pulse, the production rate is ~2.6 times higher and the mean size of the NPs is reduced by ~1/5 with a delay of 2 ps. The abnormal enhancement in the production rate is obtained at pulse delays Δt > 200 fs. The production-rate enhancement is mainly attributed to high photon absorption efficiency. It is caused by an increase in localized transient electron density, which results from the first sub-pulse ionization of ethanol molecules before the second sub-pulse arrives. The phase-change mechanism at a critical point might reduce nanoparticle size.

  1. Optimal filter bandwidth for pulse oximetry

    Science.gov (United States)

    Stuban, Norbert; Niwayama, Masatsugu

    2012-10-01

    Pulse oximeters contain one or more signal filtering stages between the photodiode and microcontroller. These filters are responsible for removing the noise while retaining the useful frequency components of the signal, thus improving the signal-to-noise ratio. The corner frequencies of these filters affect not only the noise level, but also the shape of the pulse signal. Narrow filter bandwidth effectively suppresses the noise; however, at the same time, it distorts the useful signal components by decreasing the harmonic content. In this paper, we investigated the influence of the filter bandwidth on the accuracy of pulse oximeters. We used a pulse oximeter tester device to produce stable, repetitive pulse waves with digitally adjustable R ratio and heart rate. We built a pulse oximeter and attached it to the tester device. The pulse oximeter digitized the current of its photodiode directly, without any analog signal conditioning. We varied the corner frequency of the low-pass filter in the pulse oximeter in the range of 0.66-15 Hz by software. For the tester device, the R ratio was set to R = 1.00, and the R ratio deviation measured by the pulse oximeter was monitored as a function of the corner frequency of the low-pass filter. The results revealed that lowering the corner frequency of the low-pass filter did not decrease the accuracy of the oxygen level measurements. The lowest possible value of the corner frequency of the low-pass filter is the fundamental frequency of the pulse signal. We concluded that the harmonics of the pulse signal do not contribute to the accuracy of pulse oximetry. The results achieved by the pulse oximeter tester were verified by human experiments, performed on five healthy subjects. The results of the human measurements confirmed that filtering out the harmonics of the pulse signal does not degrade the accuracy of pulse oximetry.

  2. Virgo cluster early-type dwarf galaxies with the Sloan Digital Sky Survey. III. Subpopulations: distributions, shapes, origins

    CERN Document Server

    Lisker, T; Binggeli, B; Glatt, K; Lisker, Thorsten; Grebel, Eva K.; Binggeli, Bruno; Glatt, Katharina

    2007-01-01

    From a quantitative analysis of 413 Virgo cluster early-type dwarf galaxies (dEs) with Sloan Digital Sky Survey imaging data, we find that the dE class can be divided into multiple subpopulations that differ significantly in their morphology and clustering properties. Three dE subclasses are shaped like thick disks and show no central clustering: (1) dEs with disk features like spiral arms or bars, (2) dEs with central star formation, and (3) ordinary, bright dEs that have no or only a weak nucleus. These populations probably formed from infalling progenitor galaxies. In contrast, ordinary nucleated dEs follow the picture of classical dwarf elliptical galaxies in that they are spheroidal objects and are centrally clustered like E and S0 galaxies, indicating that they have resided in the cluster since a long time, or were formed along with it. These results define a morphology-density relation within the dE class. We find that the difference in the clustering properties of nucleated dEs and dEs with no or only...

  3. Spectrally Shaped DP-16QAM Super-Channel Transmission with Multi-Channel Digital Back-Propagation

    Science.gov (United States)

    Maher, Robert; Xu, Tianhua; Galdino, Lidia; Sato, Masaki; Alvarado, Alex; Shi, Kai; Savory, Seb J.; Thomsen, Benn C.; Killey, Robert I.; Bayvel, Polina

    2015-02-01

    The achievable transmission capacity of conventional optical fibre communication systems is limited by nonlinear distortions due to the Kerr effect and the difficulty in modulating the optical field to effectively use the available fibre bandwidth. In order to achieve a high information spectral density (ISD), while simultaneously maintaining transmission reach, multi-channel fibre nonlinearity compensation and spectrally efficient data encoding must be utilised. In this work, we use a single coherent super-receiver to simultaneously receive a DP-16QAM super-channel, consisting of seven spectrally shaped 10GBd sub-carriers spaced at the Nyquist frequency. Effective nonlinearity mitigation is achieved using multi-channel digital back-propagation (MC-DBP) and this technique is combined with an optimised forward error correction implementation to demonstrate a record gain in transmission reach of 85%; increasing the maximum transmission distance from 3190 km to 5890 km, with an ISD of 6.60 b/s/Hz. In addition, this report outlines for the first time, the sensitivity of MC-DBP gain to linear transmission line impairments and defines a trade-off between performance and complexity.

  4. The near-IR properties and continuum shapes of high redshift quasars from the Sloan Digital Sky Survey

    Science.gov (United States)

    Pentericci, L.; Rix, H.-W.; Prada, F.; Fan, X.; Strauss, M. A.; Schneider, D. P.; Grebel, E. K.; Harbeck, D.; Brinkmann, J.; Narayanan, V. K.

    2003-10-01

    We present J-H-K' photometry for a sample of 45 high redshift quasars found by the Sloan Digital Sky Survey. The sample was originally selected on the basis of optical colors and spans a redshift range from 3.6 to 5.03. Our photometry reflects the rest-frame SED longward of Lyalpha for all redshifts. The results show that the near-IR colors of high redshift quasars are quite uniform. We have modelled the continuum shape of the quasars (from just beyond Lyalpha to ~ 4000 Å) with a power law of the form fnu ~ nu \\alpha, and find =-0.57 with a scatter of 0.33. This value is similar to what is found for lower redshift quasars over the same restframe wavelength range, and {we conclude that} there is hardly any evolution in the continuum properties of optically selected quasars up to redshift 5. The spectral indices found by combining near-IR with optical photometry are in general consistent but slightly flatter than what is found for the same quasars using the optical spectra and photometry alone, showing that the continuum region used to determine the spectral indices can somewhat influence the results.

  5. A fast and quantitative evaluation of the Aspergillus fumigatus biofilm adhesion properties by means of digital pulsed force mode

    Energy Technology Data Exchange (ETDEWEB)

    Maiorana, Alessandro [Istituto di Fisica, Università Cattolica del S. Cuore, L. go F. Vito 1, 00168 Roma (Italy); Papi, Massimiliano, E-mail: m.papi@rm.unicatt.it [Istituto di Fisica, Università Cattolica del S. Cuore, L. go F. Vito 1, 00168 Roma (Italy); Bugli, Francesca; Torelli, Riccardo [Istituto di Microbiologia, Università Cattolica del S. Cuore, L. go F. Vito 1, 00168 Roma (Italy); Maulucci, Giuseppe [Istituto di Fisica, Università Cattolica del S. Cuore, L. go F. Vito 1, 00168 Roma (Italy); Cacaci, Margherita; Posteraro, Brunella; Sanguinetti, Maurizio [Istituto di Microbiologia, Università Cattolica del S. Cuore, L. go F. Vito 1, 00168 Roma (Italy); De Spirito, Marco [Istituto di Fisica, Università Cattolica del S. Cuore, L. go F. Vito 1, 00168 Roma (Italy)

    2013-08-15

    The opportunistic pathogenic mould Aspergillus fumigatus (A. fumigatus) is an increasing cause of morbidity and mortality in immunocompromised and in part immunocompetent patients. A. fumigatus can grow in multicellular communities by the formation of a hyphal network embedded in an extracellular matrix (ECM) meanly composed by polysaccharides, melanin, proteins. Because adhesion properties is one primary factor affecting the balance between growth, detachment and biofilm formation, its quantification is essential in understanding, predicting, and modelling biofilm development. Atomic force microscopy (AFM) imaging and force spectroscopy have recently opened a range of novel applications in microbiology including the imaging and manipulation of membrane proteins at the subnanometer level, the observation of the surface of living cells at high resolution, the mapping of local properties such as surface charges, the measurement of elastic properties of cell-surface constituents and the probing of cellular interactions using functionalized probes. Nevertheless, the principal disadvantage of this approach is the relatively slow acquisition rate that makes AFM is not able to detect fast dynamics. In this study we demonstrated that digital pulsed force mode (DPFM) atomic force microscopy can be used to obtain high-resolution topographical images and to quantify the adhesion properties of the A. fumigatus biofilm with an high acquisition rate. Here we show by means of DPFM-AFM that Alginate Lyase (AlgL), an enzyme known to reduce negatively charged alginate levels in microbial biofilm, is able to reduce the biofilm adhesion forces forming several nano-fractures in the ECM. These results suggest that the AlgL could used to enhance the antifungal drugs transit through the ECM.

  6. A fast and quantitative evaluation of the Aspergillus fumigatus biofilm adhesion properties by means of digital pulsed force mode

    Science.gov (United States)

    Maiorana, Alessandro; Papi, Massimiliano; Bugli, Francesca; Torelli, Riccardo; Maulucci, Giuseppe; Cacaci, Margherita; Posteraro, Brunella; Sanguinetti, Maurizio; De Spirito, Marco

    2013-08-01

    The opportunistic pathogenic mould Aspergillus fumigatus (A. fumigatus) is an increasing cause of morbidity and mortality in immunocompromised and in part immunocompetent patients. A. fumigatus can grow in multicellular communities by the formation of a hyphal network embedded in an extracellular matrix (ECM) meanly composed by polysaccharides, melanin, proteins. Because adhesion properties is one primary factor affecting the balance between growth, detachment and biofilm formation, its quantification is essential in understanding, predicting, and modelling biofilm development. Atomic force microscopy (AFM) imaging and force spectroscopy have recently opened a range of novel applications in microbiology including the imaging and manipulation of membrane proteins at the subnanometer level, the observation of the surface of living cells at high resolution, the mapping of local properties such as surface charges, the measurement of elastic properties of cell-surface constituents and the probing of cellular interactions using functionalized probes. Nevertheless, the principal disadvantage of this approach is the relatively slow acquisition rate that makes AFM is not able to detect fast dynamics. In this study we demonstrated that digital pulsed force mode (DPFM) atomic force microscopy can be used to obtain high-resolution topographical images and to quantify the adhesion properties of the A. fumigatus biofilm with an high acquisition rate. Here we show by means of DPFM-AFM that Alginate Lyase (AlgL), an enzyme known to reduce negatively charged alginate levels in microbial biofilm, is able to reduce the biofilm adhesion forces forming several nano-fractures in the ECM. These results suggest that the AlgL could used to enhance the antifungal drugs transit through the ECM.

  7. Metal micromachining with shaped femtosecond laser pulses%整形飞秒激光金属材料精细加工

    Institute of Scientific and Technical Information of China (English)

    胡湛; 齐莹; 杨鼎; 周胜鹏; 石英; 田蕾; 王钦鑫; 丁大军

    2012-01-01

    实验通过二极管记录透射光信号随脉冲个数变化关系以及观测样品烧蚀形貌来研究不同实验条件对激光烧蚀的影响.使用的样品是厚度为50μm铝箔.实验中通过研究不同变量:激光焦点与样品的相对位置、激光的能量、背景气体压强以及脉冲形状对烧蚀加工过程和结果的影响,从而获得较好烧蚀效果的条件,达到控制烧蚀加工过程的目的.特别是通过使用不同形状的脉冲和具有一定规律的脉冲序列对样品进行烧蚀,发现某些形状的整形脉冲烧蚀结果明显优于变换极限脉冲.说明脉冲整形作为一种新的技术可以在激光精细钻孔领域得到更深入的研究和应用.%This paper studies the ablation of aluminum foil (50 μm thickness) under various conditions by observing the morphology of ablation caves and by analyzing the relationship of the photodiode signal of transmitted light and the number of pulses to penetration. In order to obtain better condition of ablation, several variable quantities in the experiment are tested) which are the pulse energy, position of laser focus relative to sample surface, ambient pressure and pulse shape. Preferable results are obtained by using some specific shaped pulses to ablate samples, compared to those obtained with transform-limited pulses, which means laser pulse shaping technology can be of important usage and application in micromachining metal material.

  8. Excitation of H$_{2}^{+}$ with one-cycle laser pulses: Shaped post-laser-field electronic oscillations, generation of higher- and lower-order harmonics

    CERN Document Server

    Paramonov, Guennaddi K; Bandrauk, Andre D

    2016-01-01

    Non Born-Oppenheimer quantum dynamics of H$_{2}^{+}$ excited by shaped one-cycle laser pulses linearly polarized along the molecular axis have been studied by the numerical solution of the time-dependent Schr\\"odinger equation within a %three-body three-dimensional model, including the internuclear separation, $R$, and the electron coordinates $z$ and $\\rho$. Laser carrier frequencies corresponding to the wavelengths $\\lambda_{l}=25$~nm through $\\lambda_{l}=400$~nm were used and the amplitudes of the pulses were chosen such that the energy of H$_{2}^{+}$ was close to its dissociation threshold at the end of any laser pulse applied. It is shown that there exists a characteristic oscillation frequency $\\omega_{\\rm osc} \\simeq 0.2265$~au (corresponding to the period of $\\tau_{\\rm osc} \\simeq 0.671$~fs and the wavelength of $\\lambda_{\\rm osc} \\simeq 200$~nm) that manifests itself as a "carrier" frequency of temporally shaped oscillations of the time-dependent expectation values $\\langle z \\rangle$ and $\\langle \\p...

  9. Detailed Characterization of Nuclear Recoil Pulse Shape Discrimination in the DarkSide-50 Direct Dark Matter Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Edkins, Erin Elisabeth [Univ. of Hawaii, Honolulu, HI (United States)

    2017-05-01

    While evidence of non-baryonic dark matter has been accumulating for decades, its exact nature continues to remain a mystery. Weakly Interacting Massive Particles (WIMPs) are a well motivated candidate which appear in certain extensions of the Standard Model, independently of dark matter theory. If such particles exist, they should occasionally interact with particles of normal matter, producing a signal which may be detected. The DarkSide-50 direct dark matter experiment aims to detect the energy of recoiling argon atoms due to the elastic scattering of postulated WIMPs. In order to make such a discovery, a clear understanding of both the background and signal region is essential. This understanding requires a careful study of the detector's response to radioactive sources, which in turn requires such sources may be safely introduced into or near the detector volume and reliably removed. The CALibration Insertaion System (CALIS) was designed and built for this purpose in a j oint effort between Fermi National Laboratory and the University of Hawaii. This work describes the design and testing of CALIS, its installation and commissioning at the Laboratori Nazionali del Gran Sasso (LNGS) and the multiple calibration campaigns which have successfully employed it. As nuclear recoils produced by WIMPs are indistinguishable from those produced by neutrons, radiogenic neutrons are both the most dangerous class of background and a vital calibration source for the study of the potential WIMP signal. Prior to the calibration of DarkSide-50 with radioactive neutron sources, the acceptance region was determined by the extrapolation of nuclear recoil data from a separate, dedicated experiment, ScENE, which measured the distribution of the pulse shape discrimination parameter, $f_{90}$, for nuclear recoils of known energies. This work demonstrates the validity of the extrapolation of ScENE values to DarkSide-50, by direct comparison of the $f_{90}$ distributio n of nuclear

  10. Author's rights in the digital age: how Internet and peer-to-peer file sharing technology shape the perception of copyrights and copywrongs

    Directory of Open Access Journals (Sweden)

    Milijana Micunovic

    2016-01-01

    Full Text Available Author's rights and copyright law have gone through quite a few changes in the 'post-print' culture of binary systems, digital formations and techno-practices. Technological development supports new concept of author's rights by promoting free internet and digital market, as well as new contemporary experience of culture that is being rooted in digital technology, mass communication and the world of multimedia and virtuality. Though computer and digital technology have served both authors and users in various ways, they have also served as a very fertile ground for sharing copyrighted content thus leading to numerous copyright infringements and conflicts with the copyright law. The aim of this paper is to identify and analyze the ways in which computer and digital technology have given rise to new trends in the production (e.g. remix culture and consumption (e.g. peer-to-peer file sharing technology of culture, but also to determine how new forms of distribution, use and sharing of digital content changed and shaped the perception of authorship in the 21st century. In order to analyze the dynamic, nature and structure by which new digital and networking technologies are affecting the concept of authorship and author's rights and to test the consistency of previously established hypotheses, we conducted a survey amongst general public. Altogether 535 questionnaires were completed. Data was analyzed using SPSS tool and quantitative method of analysis. In the analysis special attention was given to both, the concept of authorship in the digital environment and the concept of peer-to-peer file sharing technology as not so new, but still very popular networked architecture for distributing, using and sharing digital content. Results have shown that most of the respondents use peer-to-peer file sharing technology to access, consume and/or share different cultural content (e.g. movies, music, books, etc. while violating the rights of copyright holders

  11. Power nanosecond pulse shaping by means of RCD-generators with peaking circuits based on diode current breakers

    CERN Document Server

    Grekhov, I V; Korotkov, S V; Stepanyants, A L; Khristyuk, D V

    2002-01-01

    One considered the basic principles to design nanosecond region generators based on reverse-connected dynistos (RCD) with diode current breaker base output peaking circuits. Paper presents the results of experimental investigation in intense generator based on RCD, peaking pulsed transformer and high-voltage diode breaker from a set of series-connected drift diodes with abrupt reset. Generator at 1 kHz frequency commutates voltage pulses with approx 45 kV amplitude, approx 50 ns duration and approx 10 ns rise front to 25 ohm load

  12. Note: Compact high voltage pulse transformer made using a capacitor bank assembled in the shape of primary.

    Science.gov (United States)

    Shukla, Rohit; Banerjee, Partha; Sharma, Surender K; Das, Rashmita; Deb, Pankaj; Prabaharan, T; Das, Basanta; Adhikary, Biswajit; Verma, Rishi; Shyam, Anurag

    2011-10-01

    The experimental results of an air-core pulse transformer are presented, which is very compact (transformer. A high voltage capacitor assembly (pulse-forming-line capacitor, PFL) of 5.1 nF is connected with the secondary of transformer. The transformer output voltage is 160 kV in its second peak appearing in less than 2 μS from the beginning of the capacitor discharge. The primary capacitor bank can be charged up to a maximum of 18 kV, with the voltage delivery of 360 kV in similar capacitive loads.

  13. Pulse-shape discrimination of scintillation from alpha and beta particles with liquid scintillator and Geiger-mode multipixel avalanche diodes

    CERN Document Server

    Kreslo, I; Delaquis, S; Ereditato, A; Janos, S; Messina, M; Moser, U; Rossi, B; Zeller, M

    2011-01-01

    A successfull application of Geiger-mode multipixel avalanche diodes (GMAPDs) for pulse-shape discrimination in alpha-beta spectrometry using organic liquid scintillator is described in this paper. Efficient discrimination of alpha and beta components in the emission of radioactive isotopes is achieved for alpha energies above 0.3 MeV. The ultra-compact design of the scintillating detector helps to efficiently suppress cosmic-ray and ambient radiation background. This approach allows construction of hand-held robust devices for monitoring of radioactive contamination in various environmental conditions.

  14. Experimental demonstration of a FBG-based temporal optical pulse shaping scheme dual to spatial arrangements for its use in OCDMA systems

    Science.gov (United States)

    Tainta, Santiago; Amaya, Waldimar; García, Raimundo; Erro, María J.; Garde, María J.; Sales, Salvador; Muriel, Miguel A.

    2009-11-01

    We have demonstrated a reconfigurable time domain spectral phase encoding scheme for coherent optical code-divisionmultiple- access application. The proposed scheme is based on the concept of temporal pulse shaping dual to spatial arrangements. It uses Fiber Bragg Gratings as dispersive elements and electro-optic modulators. The data speed is 1.25 Gbps and the code is introduced at 10 Gcps, using a subset of the Hadamard codes with a length of 8 chips within a 0.7 nm optical window. The system is electrically reconfigurable and compatible with fiber systems and permits scalability in the size of the codes by modifying only the phase modulator velocity.

  15. Alpha-gamma pulse shape discrimination in CsI:Tl, CsI:Na and BaF sub 2 scintillators

    CERN Document Server

    Dinca, L E; Haas, J; Bom, V R; Eijk, C W E

    2002-01-01

    Some scintillating materials offer the possibility of measuring well separated alpha and gamma scintillation response using a single crystal. Eventually aiming at thermal neutron detection using sup 6 Li or sup 1 sup 0 B admixture, pulse shape discrimination measurements were made on three scintillators: CsI:Tl, CsI:Na and pure BaF sub 2 crystals. A very good alpha/gamma discrimination was obtained using sup 2 sup 2 Na, sup 2 sup 4 sup 1 Am (gamma) and sup 2 sup 4 sup 4 Cm (alpha) radioactive sources.

  16. Bandwidth and repetition rate programmable Nyquist sinc-shaped pulse train source based on intensity modulators and four-wave mixing.

    Science.gov (United States)

    Cordette, S; Vedadi, A; Shoaie, M A; Brès, C-S

    2014-12-01

    We propose and experimentally demonstrate an all-optical Nyquist sinc-shaped pulse train source based on intensity modulation and four-wave mixing. The proposed scheme allows for the tunability of the bandwidth and the full flexibility of the repetition rate in the limit of the electronic bandwidth of the modulators used through the flexible synthesis of rectangular frequency combs. Bandwidth up to 360 GHz at 40 GHz rate and up to 45 frequency lines at 5 GHz rate are demonstrated with 40 GHz modulators.

  17. FIPSER: Performance Study of a Readout Concept With Few Digitization Levels for Fast Signals

    CERN Document Server

    Limyansky, Brent; Cressler, John D; Otte, Adam Nepomuk; Taboada, Ignacio; Ulusoy, Cagri

    2016-01-01

    We discuss the performance of a readout system, Fixed Pulse Shape Efficient Readout (FIPSER), to digitize signals from detectors with a fixed pulse shape. In this study we are mainly interested in the readout of fast photon detectors like photomultipliers or Silicon photomultipliers. But the concept can be equally applied to the digitization of other detector signals. FIPSER is based on the flash analog to digital converter (FADC) concept, but has the potential to lower costs and power consumption by using an order of magnitude fewer discrete voltage levels. Performance is bolstered by combining the discretized signal with the knowledge of the underlying pulse shape. Simulated FIPSER data was reconstructed with two independent methods. One using a maximum likelihood method and the other using a modified chisquared test. Both methods show that utilizing 12 discrete voltage levels with a sampling rate of 4 samples per full width half maximum (FWHM) of the pulse achieves an amplitude resolution that is better th...

  18. Laser pulse shaping for optimal control of multiphoton dissociation in a diatomic molecule using genetic algorithm optimization

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Sitansh, E-mail: sitansh@research.iiit.ac.in [Center for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology, Hyderabad 500 032 (India); Singh, Harjinder, E-mail: harjinder.singh@iiit.ac.in [Center for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology, Hyderabad 500 032 (India)

    2011-11-18

    Graphical abstract: Application of genetic algorithm optimization to control dissociation process in the ground electronic state of HF molecule is demonstrated. Highlights: Black-Right-Pointing-Pointer Genetic algorithm optimization for the design of laser pulses. Black-Right-Pointing-Pointer Control of dissociation process in the ground electronic state of HF molecule. Black-Right-Pointing-Pointer Two types of pulses, one with fixed frequency components and the other having non-deterministic components. Black-Right-Pointing-Pointer Optimized laser fields possess simple time and frequency structures. - Abstract: We have applied genetic algorithm optimization for the design of laser pulses to control dissociation process in the ground electronic state of HF molecule, within the mathematical framework of optimal control theory. In order to design the experimentally feasible laser fields, we coded the small set of selected field parameters in the GA parameter space. Two types of pulses, one with fixed frequency components and the other having non-deterministic components have been designed. Optimized laser field obtained using this approach, possesses simple time and frequency structures. We show that the fields having non-deterministic frequency components lead to greater dissociation probability compared to the ones having deterministic frequency components.

  19. Pulse width shaping of passively mode-locked soliton fiber laser via polarization control in carbon nanotube saturable absorber.

    Science.gov (United States)

    Jeong, Hwanseong; Choi, Sun Young; Rotermund, Fabian; Yeom, Dong-Il

    2013-11-04

    We report the continuous control of the pulse width of a passively mode-locked fiber laser via polarization state adjustment in a single-walled carbon nanotube saturable absorber (SWCNT-SA). The SWCNT, coated on the side-polished fiber, was fabricated with optimized conditions and used for stable mode-locking of the fiber laser without Q-switching instabilities for any polarization state of the laser intra-cavity. The 3-dB spectral bandwidth of the mode-locked pulses can be continuously tuned from 1.8 nm to 8.5 nm with the polarization control for a given laser cavity length and applied pump power. A pulse duration varying from 470 fs to 1.6 ps was also observed with a change in the spectral bandwidth. The linear and the nonlinear transmission properties of the SA were analyzed, and found to exhibit different modulation depths depending on the input polarization state in the SA. The largest modulation depth of the SA was observed at the polarization state of the transverse electric mode that delivers shortest pulses at the laser output.

  20. Pulse shaping for 112 Gbit/s polarization multiplexed 16-QAM signals using a 21 GSa/s DAC.

    Science.gov (United States)

    Cartledge, John C; Downie, John D; Hurley, Jason E; Karar, Abdullah S; Jiang, Ying; Roberts, Kim

    2011-12-12

    The implications of increasing the symbol rate for a given digital-to-analog converter (DAC) sampling rate are investigated by considering the generation of 112 Gbit/s PM 16-QAM signals (14 Gsym/s) using a 21 GSa/s DAC with 6-bit resolution.