WorldWideScience

Sample records for alpha-gamma pulse shape

  1. 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.

  2. New pulse shape analysis method with multi-shaping amplifiers

    International Nuclear Information System (INIS)

    A novel pulse-shape-analysis method that uses 'similarity' to recognize an individual pulse shape is presented. We obtain four pulse heights by using four linear amplifiers with time constants of 0.5, 2, 3 and 6 μs. We treat a combination of four pulse heights as a pattern vector. Each pulse shape is analyzed by using the similarity. The method has been applied to the improvement of characteristics of a CdZnTe semiconductor detector (eV Products 180.5.5.5s, 5x5x5 mm). A CdZnTe semiconductor detector has prominent properties that are desirable as a radiation detector. The high atomic numbers indicate a larger detection efficiency for X or gamma rays than that of other semiconductor detectors such as Si or Ge ones. The large forbidden band gap energy permits room temperature operation. However, as is common with other compound semiconductor materials, the pulse shapes from CdZnTe detectors differ from event to event depending on the positions of radiation interaction because of the different mobilities of the holes and electrons, and the short life time of the holes or trapping in the bulk. We tried to correct each pulse height by analyzing and compensating through the analysis of the pulse shapes with the similarity. After the correction procedure with the similarity, characteristics of the energy spectrum of the CdZnTe semiconductor detector such as peak-to-valley ratio or photopeak efficiency were improved. The results are tabulated. This method is simple and useful for pulse shape analysis, which can be used for many other applications

  3. Attosecond pulse shaping using partial phase matching

    International Nuclear Information System (INIS)

    We propose a method for programmable shaping of the amplitude and phase of the extreme ultraviolet and x-ray attosecond pulses produced by high-order harmonic generation. It overcomes the bandwidth limitations of existing spectral filters and enables removal of the intrinsic attosecond chirp as well as the synthesis of pulse sequences. It is based on partial phase matching using a longitudinally addressable modulation. Although the method is in principle applicable to any form of partial phase matching, we focus on quasi-phase matching using a counterpropagating pulse train. We present simulations of the production of isolated attosecond pulses at 250 eV, including a 31 as transform-limited pulse, tunably chirped pulses and double pulses. (paper)

  4. Modified pulse shapes for effective neural stimulation

    Directory of Open Access Journals (Sweden)

    Lorenz eHofmann

    2011-09-01

    Full Text Available Electrical stimulation of neuronal structures is used as treatment of many neu- rological disorders, e.g. for the treatment of Parkinsons disease via deep brain stimulation. To reduce side effects, to avoid tissue or electrode damage and to increase battery lifetimes, an effective but gentle electrical stimulation is of prime importance. We study different modified pulse shapes for application in deep brain stimulation with respect to their efficiency to initiate neuronal activity. Numeri- cal simulations of two mathematical neuron models are performed to investigate the effectiveness of different modified pulse shapes. According to our results, the considered pulse shapes show a considerably increased efficiency in terms of both activation and entrainment of neural activity. We find that the introduction of a gap of specific and optimized duration in a biphasic pulse and the reversal of the stan- dard pulse phase order yield stimulation protocols that may increase the efficiency and therefore reduce the energy consumption of stimulation. The improvements are achieved only by simple modifications of existing stimulation techniques. The modification of the pulse shapes results in an improvement of up to 50% for both the activation of resting neurons and the entrainment of bursting neurons.

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

    International Nuclear Information System (INIS)

    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.)

  6. 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.)

  7. Attosecond pulse shaping using partial phase matching

    OpenAIRE

    Austin, Dane R.; Biegert, Jens

    2014-01-01

    We propose a method for programmable shaping of the amplitude and phase of the XUV and x-ray attosecond pulses produced by high-order harmonic generation. It overcomes the bandwidth limitations of existing spectral filters and enables removal of the intrinsic attosecond chirp as well as the synthesis of pulse sequences. It is based on partial phase matching, such as quasi-phase matching, using a longitudinally addressable modulation.

  8. Laser pulse shaping with liquid crystals

    OpenAIRE

    Martín Pereda, José Antonio; Muriel Fernández, Miguel Ángel

    1983-01-01

    A method of unpolarized laser pulses shaping is reported. The basis of the method is the use of an hybrid optical bistable device with nematic liquid-crystals, similar to the one previously reported by us. A sample of the input light constrols, by an asymmetrical electronic comparator, a 1 x 2 electro-optical total switch. The output pulses are reshaped and maintain the same polarization properties as the input light. From triangular input light signals, symmetriacl and asymmetrical output pu...

  9. Interactions between butterfly-shaped pulses in the inhomogeneous media

    International Nuclear Information System (INIS)

    Pulse interactions affect pulse qualities during the propagation. Interactions between butterfly-shaped pulses are investigated to improve pulse qualities in the inhomogeneous media. In order to describe the interactions between butterfly-shaped pulses, analytic two-soliton solutions are derived. Based on those solutions, influences of corresponding parameters on pulse interactions are discussed. Methods to control the pulse interactions are suggested. - Highlights: • Interactions between butterfly-shaped pulses are investigated. • Methods to control the pulse interactions are suggested. • Analytic two-soliton solutions for butterfly-shaped pulses are derived

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. Optical pulse shaping approaches to coherent control

    International Nuclear Information System (INIS)

    The last part of the twentieth century has experienced a huge resurge of activity in the field of coherent light-matter interaction, more so in attempting to exert control over such interactions. Birth of coherent control was originally spurred by the theoretical understanding of the quantum interferences that lead to energy randomization and experimental developments in ultrafast laser spectroscopy. The theoretical predictions on control of reaction channels or energy randomization processes are still more dramatic than the experimental demonstrations, though this gap between the two is consistently reducing over the recent years with realistic theoretical models and technological developments. Experimental demonstrations of arbitrary optical pulse shaping have made some of the previously impracticable theoretical predictions possible to implement. Starting with the simple laser modulation schemes to provide proof-of-the-principle demonstrations, feedback loop pulse shaping systems have been developed that can actively manipulate some atomic and molecular processes. This tremendous experimental boost of optical pulse shaping developments has prospects and implications into many more new directions, such as quantum computing and terabit/sec data communications. This review captures certain aspects and impacts of optical pulse shaping into the fast developing areas of coherent control and other related fields. Currently available reviews focus on one or the other detailed aspects of coherent control, and the reader will be referred to such details as and when necessary for issues that are dealt in brief here. We will focus on the current issues including control of intramolecular dynamics and make connections to the future concepts, such as, quantum computation, biomedical applications, etc

  15. 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.

  16. 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.

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

    OpenAIRE

    Nor Adibah Ibrahim; Razali Ngah; Hamza M. R. Al-Khafaji

    2015-01-01

    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.

  18. 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....

  19. 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.

  20. 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.

  1. Energy dependence of pulse shapes in liquid scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Savran, D.; Glorius, J.; Loeher, B.; Pietralla, N.; Simon, V.; Sonnabend, K. [Institut fuer Kernphysik, (Germany); Miklavec, M.; Vencelj, M. [Institut Jozef Stefan (Slovenia)

    2009-07-01

    In ({gamma},n) experiments, e.g. at the NEPTUN photon tagger system at the S-DALINAC, the neutron spectroscopy has to be realized in an environment of high photon background and therefore an effective discrimination between photons and neutrons is mandatory. Liquid scintillators like BC501A allow a separation of neutrons and photons based on a pulse shape analysis of the subsequent photomultiplier pulses. However, the quality of this separation is not constant, but varies with the incident neutron energy. The energy dependence of the pulse shapes and the resulting separation is studied in detail using digital pulse shape analysis. First results are presented.

  2. UV pulse shaping for the photocathode RF gun

    Energy Technology Data Exchange (ETDEWEB)

    Yan Lixin, E-mail: yanlx@mail.tsinghua.edu.cn [Accelerator Laboratory, Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory of Particle and Radiation Imaging (Tsinghua University), Ministry of Education, Beijing 100084 (China); Key Laboratory of High Energy Radiation Imaging Fundamental Science for National Defense, Beijing 100084 (China); Du Qiang; Du Yingchao; Hua Jianfei; Huang Wenhui; Tang Chuanxiang [Accelerator Laboratory, Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory of Particle and Radiation Imaging (Tsinghua University), Ministry of Education, Beijing 100084 (China); Key Laboratory of High Energy Radiation Imaging Fundamental Science for National Defense, Beijing 100084 (China)

    2011-05-01

    Recently, manipulation with the drive laser plays a significant role in high brightness electron beam production by the photocathode RF gun. The article takes efforts on the temporal shaping of the driving laser for the photocathode RF gun. Method based on pulse stacking by birefringent crystal of {alpha}-BBO serials was tried to directly shape ultraviolet laser pulse. Using four pieces of {alpha}-BBO crystals to separate an input UV pulse with appropriate duration into 16 sub-pulses can form a ps-spaced pulse train suitable for coherent THz production. The group delay dispersion induced by the crystals was also carefully considered. To avoid beam deterioration by long path propagation, imaging relay of the shaped pulse was applied.

  3. Arterial pulse shape measurement using self-mixing inteferometry

    Science.gov (United States)

    Hast, Jukka T.; Myllyla, Risto A.; Sorvoja, Hannu; Miettinen, Jari

    2003-07-01

    This paper investigates the correlation between the shape of the first derivative of a blood pressure pulse and the corresponding Doppler spectrogram, reconstructed from a Doppler signal produced by the movement of the skin above the radial artery in the human wrist. The aim is to study to what extent the arterial pulse shape can be measured using self-mixing interferometry. To obtain a point of reference, a commercial non-invasive blood pressure monitor was first used to measure both blood pressure and pulse shape. Then, a self-mixing interferometer was applied to measure the arterial pulse above the radial artery. Measurements on 10 volunteers yielded a total of 738 pulses for analysis. A cross correlation of 0.84 +/- 0.05 was established between the shape of the first derivative of the pressure pulse and the Doppler spectrogram. Using an empirical constant of 0.7 as a limit for successfully detected pulses produced a detection accuracy of 95.7%. The results show that self-mixing interferometry lends itself to the measurement of the arterial pulse shape, and that the thus obtained shape is in good agreement with that produced by a commercial blood pressure monitor.

  4. New pulse-shape analysis method with multi-shaping amplifiers

    CERN Document Server

    Sakai, H; Takenaka, Y; Mori, C; Iguchi, T

    1999-01-01

    A novel pulse-shape analysis method that uses similarity to recognize an individual pulse shape is presented in this paper. We obtain four pulse heights by using four linear amplifiers with different shaping time constants. We treat a combination of the four pulse heights as a pattern vector. A similarity of the pulse shape can be obtained by comparison between the pattern vector and a discriminant vector which was given in advance. Each pulse shape is analyzed by using the similarity. The method has been applied for the improvement of characteristics of a CdZnTe semiconductor detector. The characteristics of the energy spectrum of the CdZnTe detector such as the photopeak efficiency or the peak-to-valley ratio are improved after the correction procedure with the similarity.

  5. Pulse Shape Filtering in Wireless Communication-A Critical Analysis

    Directory of Open Access Journals (Sweden)

    A. S Kang

    2011-03-01

    Full Text Available The goal for the Third Generation (3G of mobile communications system is to seamlessly integrate a wide variety of communication services. The rapidly increasing popularity of mobile radio services has created a series of technological challenges. One of this is the need for power and spectrally efficient modulation schemes to meet the spectral requirements of mobile communications. Pulse shaping plays a crucial role in spectral shaping in the modern wireless communication to reduce the spectral bandwidth. Pulse shaping is a spectral processing technique by which fractional out of band power is reduced for low cost, reliable , power and spectrally efficient mobile radio communication systems. It is clear that the pulse shaping filter not only reduces inter-symbol interference (ISI, but it also reduces adjacent channel interference. The present paper deals with critical analysis of pulse shaping in wireless communication.

  6. Pulse shape discrimination studies in a liquid Argon scintillation detector

    OpenAIRE

    Pollmann, T.

    2007-01-01

    Liquid rare gases have been gaining popularity as detector media in rare event searches, especially dark matter experiments, and one factor driving their adoption is the possibility to recognise different types of ionizing radiation by the pulse shapes they evoke. This work on pulse shape discrimination in a liquid argon scintillation detector was done in the framework of the GERDA experiment, where liquid argon scintillation signals may be used for background suppression purposes. Liquid arg...

  7. 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.

  8. Pulse Shaping Entangling Gates and Error Supression

    Science.gov (United States)

    Hucul, D.; Hayes, D.; Clark, S. M.; Debnath, S.; Quraishi, Q.; Monroe, C.

    2011-05-01

    Control of spin dependent forces is important for generating entanglement and realizing quantum simulations in trapped ion systems. Here we propose and implement a composite pulse sequence based on the Molmer-Sorenson gate to decrease gate infidelity due to frequency and timing errors. The composite pulse sequence uses an optical frequency comb to drive Raman transitions simultaneously detuned from trapped ion transverse motional red and blue sideband frequencies. The spin dependent force displaces the ions in phase space, and the resulting spin-dependent geometric phase depends on the detuning. Voltage noise on the rf electrodes changes the detuning between the trapped ions' motional frequency and the laser, decreasing the fidelity of the gate. The composite pulse sequence consists of successive pulse trains from counter-propagating frequency combs with phase control of the microwave beatnote of the lasers to passively suppress detuning errors. We present the theory and experimental data with one and two ions where a gate is performed with a composite pulse sequence. This work supported by the U.S. ARO, IARPA, the DARPA OLE program, the MURI program; the NSF PIF Program; the NSF Physics Frontier Center at JQI; the European Commission AQUTE program; and the IC postdoc program administered by the NGA.

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

    International Nuclear Information System (INIS)

    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.

  10. 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.

  11. Shaping quantum pulses of light via coherent atomic memory

    CERN Document Server

    Eisaman, M D; André, A; Massou, F; Zibrov, A S; Lukin, M D

    2004-01-01

    We describe a technique for generating pulses of light with controllable photon numbers, propagation direction, timing, and pulse shapes. The technique is based on preparation of an atomic ensemble in a state with a desired number of atomic spin excitations, which is later converted into a photon pulse. Spatio-temporal control over the pulses is obtained by exploiting long-lived coherent memory for photon states and electromagnetically induced transparency (EIT) in an optically dense atomic medium. Using photon counting experiments we observe generation and shaping of few-photon sub-Poissonian light pulses. We discuss prospects for controlled generation of high-purity n-photon Fock states using this technique.

  12. 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.

  13. 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.

  14. 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.

  15. Resonant pulse-shaping power supply for radar transmitters

    OpenAIRE

    Bell Rodriguez, Miguel Victoria Ramo; Roberg, Michael; Pack, Riley; Garcia Fernandez, Pablo; Alarcón Cot, Eduardo José; Popoviç, Zoya; Maksimovic, Dragan

    2012-01-01

    The final radiofrequency power amplifier (PA) of a radar transmitter module is a large factor in system efficiency. Typical radar transmitter signals are frequency-modulated with constant-amplitude pulse envelopes in order to optimize efficiency, resulting in spectral broadening and power radiated outside of the radar frequency band. This paper demonstrates a PA with a dynamic power supply which enables high efficiency while reducing the spectral emissions. The resonant pulse-shaping power su...

  16. Current pulse shaping of the load current on PTS

    Science.gov (United States)

    Xia, Minghe; Li, Fengping; Ji, Ce; Wei, Bing; Feng, Shuping; Wang, Meng; Xie, Weiping

    2016-02-01

    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.

  17. 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.

  18. A fully integrated 16 channel digitally trimmed pulse shaping amplifier

    International Nuclear Information System (INIS)

    A fully integrated CMOS pulse shaping amplifier has been developed at LBL. All frequency dependent networks are included on the chip. Provision is made for tuning to compensate for process variations. The overall architecture and details of the circuitry are discussed. Test results are presented

  19. 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.

  20. Swift Observations of Gamma-Ray Burst Pulse Shapes: GRB Pulse Spectral Evolution Clarified

    Science.gov (United States)

    Hakkila, Jon; Lien, Amy; Sakamoto, Takanori; Morris, David; Neff, James E.; Giblin, Timothy W.

    2015-12-01

    Isolated Swift gamma-ray burst (GRB) pulses, like their higher-energy BATSE counterparts, emit the bulk of their pulsed emission as a hard-to-soft component that can be fitted by the Norris et al. empirical pulse model. This signal is overlaid by a fainter, three-peaked signal that can be modeled by the residual fit of Hakkila & Preece: the two fits combine to reproduce GRB pulses with distinctive three-peaked shapes. The precursor peak appears on or before the pulse rise and is often the hardest component, the central peak is the brightest, and the decay peak converts exponentially decaying emission into a long, soft, power-law tail. Accounting for systematic instrumental differences, the general characteristics of the fitted pulses are remarkably similar. Isolated GRB pulses are dominated by hard-to-soft evolution; this is more pronounced for asymmetric pulses than for symmetric ones. Isolated GRB pulses can also exhibit intensity tracking behaviors that, when observed, are tied to the timing of the three peaks: pulses with the largest maximum hardnesses are hardest during the precursor, those with smaller maximum hardnesses are hardest during the central peak, and all pulses can re-harden during the central peak and/or during the decay peak. Since these behaviors are essentially seen in all isolated pulses, the distinction between “hard-to-soft and “intensity-tracking” pulses really no longer applies. Additionally, the triple-peaked nature of isolated GRB pulses seems to indicate that energy is injected on three separate occasions during the pulse duration: theoretical pulse models need to account for this.

  1. 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.

  2. Digital pulse-shape processing for CdTe detectors

    Science.gov (United States)

    Bargholtz, Chr.; Fumero, E.; Mårtensson, L.; Wachtmeister, S.

    2001-09-01

    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. Digital pulse-shape processing for CdTe detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bargholtz, Chr.; Fumero, E.; Maartensson, L. E-mail: martensson@physto.se; Wachtmeister, S

    2001-09-21

    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.

  4. 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.

  5. 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.

  6. 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...

  7. Pulse Shape Simulation for a GERDA Phase II Prototype Detector

    International Nuclear Information System (INIS)

    The Germanium Detector Array Experiment, GERDA, is designed for the search for ''neutrinoless double beta decay'' (0νββ) of 76Ge. Germanium detectors enriched in the isotope 76Ge are used. Since 0νββ has a very long half-live, very few signal events are expected and an extremely low background rate is crucial. Signal events have two electrons in the final state which deposit their energy predominantly locally. A large fraction of background events deposit their energy in multiple interactions at different positions inside the detector. Pulse Shape Analysis is used to distinguish between background-like, multi site events (MSE) and signal-like events, single site events (SSE). To verify the analysis a Pulse Shape Simulation (PSS) was developed. The methods to calculate the internal electric field of the detector and the corresponding weighting-fields needed to simulate pulse shapes are discussed. Furthermore it is shown how mirror pulses in segmented detectors can be used to reconstruct the location of interactions.

  8. Realizing Ultrafast Electron Pulse Self-Compression by Femtosecond Pulse Shaping Technique.

    Science.gov (United States)

    Qi, Yingpeng; Pei, Minjie; Qi, Dalong; Yang, Yan; Jia, Tianqing; Zhang, Shian; Sun, Zhenrong

    2015-10-01

    Uncorrelated position and velocity distribution of the electron bunch at the photocathode from the residual energy greatly limit the transverse coherent length and the recompression ability. Here we first propose a femtosecond pulse-shaping method to realize the electron pulse self-compression in ultrafast electron diffraction system based on a point-to-point space-charge model. The positively chirped femtosecond laser pulse can correspondingly create the positively chirped electron bunch at the photocathode (such as metal-insulator heterojunction), and such a shaped electron pulse can realize the self-compression in the subsequent propagation process. The greatest advantage for our proposed scheme is that no additional components are introduced into the ultrafast electron diffraction system, which therefore does not affect the electron bunch shape. More importantly, this scheme can break the limitation that the electron pulse via postphotocathode static compression schemes is not shorter than the excitation laser pulse due to the uncorrelated position and velocity distribution of the initial electron bunch. PMID:26722884

  9. Swift Observations of Gamma-Ray Burst Pulse Shapes: GRB Pulse Spectral Evolution Clarified

    CERN Document Server

    Hakkila, Jon; Sakamoto, Takanori; Morris, David; Neff, James E; Giblin, Timothy W

    2015-01-01

    Isolated Swift gamma-ray burst (GRB) pulses, like their higher-energy BATSE counterparts, emit the bulk of their pulsed emission as a hard-to-soft component that can be fitted by the Norris et al. (2005) empirical pulse model. This signal is overlaid by a fainter, three-peaked signal that can be modeled by an empirical wave-like function (Hakkila and Preece, 2014): the two fits combine to reproduce GRB pulses with distinctive three-peaked shapes. The precursor peak appears on or before the pulse rise and is often the hardest component, the central peak is the brightest, and the decay peak converts exponentially decaying emission into a long, soft, power-law tail. Accounting for systematic instrumental differences, the general characteristics of the fitted pulses are remarkably similar. Isolated GRB pulses are dominated by hard-to-soft evolution; this is more pronounced for asymmetric pulses than for symmetric ones. Isolated GRB pulses can also exhibit intensity tracking behaviors that, when observed, are tied...

  10. Pulse-shape discrimination in NE213 liquid scintillator detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cavallaro, M., E-mail: manuela.cavallaro@lns.infn.it [INFN-Laboratori Nazionali del Sud, Catania (Italy); CSFNSM, Catania (Italy); Tropea, S. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); Agodi, C. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Assié, M.; Azaiez, F. [Institut de Physique Nucléaire, Université Paris-Sud-11-CNRS/IN2P3, 91406 Orsay (France); Boiano, C. [INFN - Sezione di Milano, Milano (Italy); Bondì, M.; Cappuzzello, F.; Carbone, D. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); De Napoli, M. [INFN - Sezione di Catania, Catania (Italy); Séréville, N. de [Institut de Physique Nucléaire, Université Paris-Sud-11-CNRS/IN2P3, 91406 Orsay (France); Foti, A. [Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); INFN - Sezione di Catania, Catania (Italy); Linares, R. [Instituto de Física da Universidade Federal Fluminense, Rio de Janeiro, Niterói, RJ (Brazil); Nicolosi, D. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); Scarpaci, J.A. [Institut de Physique Nucléaire, Université Paris-Sud-11-CNRS/IN2P3, 91406 Orsay (France)

    2013-02-01

    The 16-channel fast stretcher BaFPro module, originally developed for processing signals of Barium Fluoride scintillators, has been modified to make a high performing analog pulse-shape analysis of signals from the NE213 liquid scintillators of the EDEN neutron detector array. The module produces two Gaussian signals, whose amplitudes are proportional to the height of the fast component of the output light and to the total energy deposited into the scintillator, respectively. An in-beam test has been performed at INFN-LNS (Italy) demonstrating a low detection threshold, a good pulse-shape discrimination even at low energies and a wide dynamic range for the measurement of the neutrons energy.

  11. Fourier synthesis of radiofrequency nanomechanical pulses with different shapes

    Science.gov (United States)

    Schülein, Florian J. R.; Zallo, Eugenio; Atkinson, Paola; Schmidt, Oliver G.; Trotta, Rinaldo; Rastelli, Armando; Wixforth, Achim; Krenner, Hubert J.

    2015-06-01

    The concept of Fourier synthesis is heavily used in both consumer electronic products and fundamental research. In the latter, pulse shaping is key to dynamically initializing, probing and manipulating the state of classical or quantum systems. In NMR, for instance, shaped pulses have a long-standing tradition and the underlying fundamental concepts have subsequently been successfully extended to optical frequencies and even to the implementation of quantum gate operations. Transferring these paradigms to nanomechanical systems requires tailored nanomechanical waveforms. Here, we report on an additive Fourier synthesizer for nanomechanical waveforms based on monochromatic surface acoustic waves. As a proof of concept, we electrically synthesize four different elementary nanomechanical waveforms from a fundamental surface acoustic wave at f1 ≈ 150 MHz using a superposition of up to three discrete harmonics. We use these shaped pulses to interact with an individual sensor quantum dot and detect their deliberately and temporally modulated strain component via the optomechanical quantum dot response. Importantly, and in contrast to direct mechanical actuation by bulk piezoactuators, surface acoustic waves provide much higher frequencies (>20 GHz ref. 10) to resonantly drive mechanical motion. Thus, our technique uniquely allows coherent mechanical control of localized vibronic modes of optomechanical crystals, even in the quantum limit when cooled to the vibrational ground state.

  12. 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.

  13. 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.)

  14. Pulse shapes and surface effects in segmented germanium detectors

    International Nuclear Information System (INIS)

    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 76Ge. The discovery of this decay could help to answer the open questions. In the GERDA experiment, germanium detectors enriched in the isotope 76Ge 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.)

  15. Pulse shape discrimination studies of Phase I Ge-detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kirsch, Andrea [MPI fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Collaboration: GERDA-Collaboration

    2013-07-01

    The GERmanium Detector Array experiment aims to search for the neutrinoless double beta decay (0νββ) of {sup 76}Ge by using isotopically enriched germanium crystals as source and detector simultaneously. The bare semiconductor diodes are operated in liquid argon at cryogenic temperatures in an ultra-low background environment. In addition, Gerda applies different active background reduction techniques, one of which is pulse shape discrimination studies of the current Phase I germanium detectors. The analysis of the signal time structure provides an important tool to distinguish single site events (SSE) of the ββ-decay from multi site events (MSE) of common gamma-ray background or surface events. To investigate the correlation between the signal shape and the interaction position, a new, also to the predominantly deployed closed-ended coaxial HPGe detectors applicable analysis technique has been developed. A summary of the used electronic/detector assembly is given and followed by a discussion of the performed classification procedure by means of accurate pulse shape simulations of 0νββ-like signals. Finally, the obtained results are presented along with an evaluation of the relevance for the Gerda experiment.

  16. Pulse-shape discrimination technique in radioanalytical methods

    International Nuclear Information System (INIS)

    Several successful techniques have been developed to eliminate unwanted background level in experimental radiation spectra. One of the background-reduction techniques is pulse-shape discrimination (PSD) which is based on the fact that different particles or quanta give rise to different spectrometer response, i.e. to different signal shapes. The shapes can be recognized and analyzed by appropriate electronic circuits which can measure either the rise time or the fall time of the pulses. The PSD technique has been suggested for different particle/background separations (such as n/γ, α/γ, α/proton or αa/electron separations). It has been successfully applied i.e. in separation of (fast) neutrons from intensive gamma background or charged particles from gammas. Recently the principle of the PSD has been applied in the construction of special ORTEC and CANBERRA spectroscopic modules. In this study we have employed the principle of PSD in two different radioanalytical methods developed in the Nuclear Research and Nuclear Physics Institutes in Rez. One of the methods concerns with the determination of uranium by delayed neutron counting (DNC), the second method is known as neutron depth profiling (NDP). An effective elimination of unwanted background signals in measured radiation spectra has been proved. At least two orders of magnitude of background level suppression has been achieved independently of employed PSD circuits. The PSD technique has substantially improved detection limits of the DNC and NDP facilities. (author)

  17. 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.

  18. Optimizing coherent anti-Stokes Raman scattering by genetic algorithm controlled pulse shaping

    Science.gov (United States)

    Yang, Wenlong; Sokolov, Alexei

    2010-10-01

    The hybrid coherent anti-Stokes Raman scattering (CARS) has been successful applied to fast chemical sensitive detections. As the development of femto-second pulse shaping techniques, it is of great interest to find the optimum pulse shapes for CARS. The optimum pulse shapes should minimize the non-resonant four wave mixing (NRFWM) background and maximize the CARS signal. A genetic algorithm (GA) is developed to make a heuristic searching for optimized pulse shapes, which give the best signal the background ratio. The GA is shown to be able to rediscover the hybrid CARS scheme and find optimized pulse shapes for customized applications by itself.

  19. 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.

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

    OpenAIRE

    Nor Adibah Ibrahim; Razali Ngah; Hamza M. R. Al-Khafaji

    2014-01-01

    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...

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

    OpenAIRE

    BARRAJ Imen; TRABELSI Hatem; Masmoudi, Mohamed

    2014-01-01

    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 studi...

  2. Spatial resolution attainable in germanium detectors by pulse shape analysis

    International Nuclear Information System (INIS)

    There are several applications for which it is desirable to calculate the locations and energies of individual gamma-ray interactions within a high purity germanium (HPGe) detector. These include gamma-ray imaging and Compton suppression. With a segmented detector this can be accomplished by analyzing the pulse shapes of the signals from the various segments. We examine the fundamental limits to the spatial resolution attainable with this approach. The primary source of error is the series noise of the field effect transistors (FETs) at the inputs of the charge amplifiers. We show how to calculate the noise spectral density at the output of the charge amplifiers due to an optimally selected FET. This calculation is based only on the detector capacitance and a noise constant for the FET technology. We show how to use this spectral density to calculate the uncertainties in parameters, such as interaction locations and energies, that are derived from pulse shape analysis using maximum likelihood estimation (MLE) applied to filtered and digitized recordings of the charge signals. Example calculations are given to illustrate our approach. Experimental results are given that demonstrate that one can construct complete systems, from detector through data analysis, that come near the theoretical limits

  3. Laboratory transferability of optimally shaped laser pulses for quantum control

    Energy Technology Data Exchange (ETDEWEB)

    Moore Tibbetts, Katharine; Xing, Xi; Rabitz, Herschel [Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (United States)

    2014-02-21

    Optimal control experiments can readily identify effective shaped laser pulses, or “photonic reagents,” that achieve a wide variety of objectives. An important additional practical desire is for photonic reagent prescriptions to produce good, if not optimal, objective yields when transferred to a different system or laboratory. Building on general experience in chemistry, the hope is that transferred photonic reagent prescriptions may remain functional even though all features of a shaped pulse profile at the sample typically 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 to still produce near optimal yields on the second laser system. Third, transferring a collection of photonic reagents optimized on the first laser system to the second laser system reproduced systematic trends in photoproduct yields upon interaction with the homologous chemical family. These three transfers of photonic reagents are demonstrated to be successful upon paying reasonable attention to overall laser system characteristics. The ability to transfer photonic reagents from one laser system to another is analogous to well-established utilitarian operating procedures with traditional chemical reagents. The practical implications of the present results for experimental quantum control are discussed.

  4. 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.

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

    Science.gov (United States)

    Töws, Albert; Lehmann, Jan; Kurtz, Alfred

    2016-06-01

    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.

  6. Pulse shape discrimination for Gerda Phase I data

    Science.gov (United States)

    Agostini, M.; Allardt, M.; Andreotti, E.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Barnabé Heider, M.; Barros, N.; Baudis, L.; Bauer, C.; Becerici-Schmidt, N.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Brudanin, V.; Brugnera, R.; Budjáš, D.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; Cossavella, F.; Demidova, E. V.; Domula, A.; Egorov, V.; Falkenstein, R.; Ferella, A.; Freund, K.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Gotti, C.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Guthikonda, K. K.; Hampel, W.; Hegai, A.; Heisel, M.; Hemmer, S.; Heusser, G.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Ioannucci, L.; Janicskó Csáthy, J.; Jochum, J.; Junker, M.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Klimenko, A.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Liu, X.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Machado, A. A.; Majorovits, B.; Maneschg, W.; Misiaszek, M.; Nemchenok, I.; Nisi, S.; O'Shaughnessy, C.; Pandola, L.; Pelczar, K.; Pessina, G.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salathe, M.; Schmitt, C.; Schreiner, J.; Schulz, O.; Schwingenheuer, B.; Schönert, S.; Shevchik, E.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Strecker, H.; Tarka, M.; Ur, C. A.; Vasenko, A. A.; Volynets, O.; von Sturm, K.; Wagner, V.; Walter, M.; Wegmann, A.; Wester, T.; Wojcik, M.; Yanovich, E.; Zavarise, P.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

    2013-10-01

    The Gerda experiment located at the Laboratori Nazionali del Gran Sasso of INFN searches for neutrinoless double beta (0 νββ) decay of 76Ge 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 76Ge 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 γ rays from 208Tl decays as well as two-neutrino double beta (2 νββ) decays of 76Ge are used as proxies for 0 νββ 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 ββ =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 νββ decay. It retains 90 % of DEP events and rejects about half of the events around Q ββ . The 2 νββ events have an efficiency of 0.85±0.02 and the one for 0 νββ decays is estimated to be . 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 νββ decays.

  7. 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.)

  8. Effect of Optical Pulse Shape on the Performance of OCDMA in Presence of GVD and Pulse Linear Chirp

    OpenAIRE

    Md. Jahedul Islam; Kalyan Kumar Halder; Md Rafiqul Islam

    2010-01-01

    In this paper, the effect of optical pulse shape on the performance of direct sequence optical code division multiple access in presence of fiber group velocity dispersion (GVD) and pulse linear chirp is analyzed. In our analysis, chirp-Gaussian shape and chirp-Hyperbolic-Secant shape optical orthogonal codes are employed as address sequence. Avalanche photodiode (APD) is used in an optical correlator receiver. The signal to noise power for the proposed system is evaluated on account of APD s...

  9. 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.

  10. Pulse shape discrimination in helium-4 scintillation detectors

    Science.gov (United States)

    Kelley, Ryan P.; Enqvist, Andreas; Jordan, Kelly A.

    2016-09-01

    Three algorithms were investigated for discriminating between neutrons and gamma rays in a pressurized 4He 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 252Cf 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.

  11. Pulse shape analysis of liquid scintillators for neutron studies

    CERN Document Server

    Marrone, S; Colonna, N; Domingo, C; Gramegna, F; González, E M; Gunsing, F; Heil, M; Kaeppeler, F; Mastinu, P F; Milazzo, P M; Papaevangelou, T; Pavlopoulos, P; Plag, R; Reifarth, R; Tagliente, G; Taín, J L; Wisshak, K

    2002-01-01

    The acquisition of signals from liquid scintillators with Flash ADC of high sampling rate (1 GS/s) has been investigated. The possibility to record the signal waveform is of great advantage in studies with gamma's and neutrons in a high count-rate environment, as it allows to easily identify and separate pile-up events. The shapes of pulses produced by gamma-rays and neutrons have been studied for two different liquid scintillators, NE213 and C sub 6 D sub 6. A 1-parameter fitting procedure is proposed, which allows to extract information on the particle type and energy. The performance of this method in terms of energy resolution and n/gamma discrimination is analyzed, together with the capability to identify and resolve pile-up events.

  12. Comparison of analog and digital pulse-shape-discrimination systems

    Science.gov (United States)

    Sosa, C. S.; Flaska, M.; Pozzi, S. A.

    2016-08-01

    Pulse shape discrimination (PSD) performance of two optimized PSD systems (one digital and one analog) is compared in this work. One system uses digital charge integration, while the other system uses analog zero crossing. Measurements were conducted with each PSD system using the CAEN V1720 (250 MHz) data acquisition system. An organic-liquid scintillator, coupled to a photo-multiplier tube, was used to detect neutrons and gamma rays from a Cf-252 spontaneous-fission source. The PSD performance of both systems was optimized and quantified using a traditional figure-of-merit (FOM) approach. FOM's were found for three, 300 keVee light-output bins, spanning from 100 to 1000 keVee, and one larger bin from 100 to 1800 keVee. Digital PSD outperformed analog PSD in the lowest light-output bin by approximately 50%, and by 11% for the highest light-output bin.

  13. Application of Bayes' theorem for pulse shape discrimination

    Science.gov (United States)

    Monterial, Mateusz; Marleau, Peter; Clarke, Shaun; Pozzi, Sara

    2015-09-01

    A Bayesian approach is proposed for pulse shape discrimination of photons and neutrons in liquid organic scinitillators. Instead of drawing a decision boundary, each pulse is assigned a photon or neutron confidence probability. This allows for photon and neutron classification on an event-by-event basis. The sum of those confidence probabilities is used to estimate the number of photon and neutron instances in the data. An iterative scheme, similar to an expectation-maximization algorithm for Gaussian mixtures, is used to infer the ratio of photons-to-neutrons in each measurement. Therefore, the probability space adapts to data with varying photon-to-neutron ratios. A time-correlated measurement of Am-Be and separate measurements of 137Cs, 60Co and 232Th photon sources were used to construct libraries of neutrons and photons. These libraries were then used to produce synthetic data sets with varying ratios of photons-to-neutrons. Probability weighted method that we implemented was found to maintain neutron acceptance rate of up to 90% up to photon-to-neutron ratio of 2000, and performed 9% better than the decision boundary approach. Furthermore, the iterative approach appropriately changed the probability space with an increasing number of photons which kept the neutron population estimate from unrealistically increasing.

  14. Application of Bayes' theorem for pulse shape discrimination

    International Nuclear Information System (INIS)

    A Bayesian approach is proposed for pulse shape discrimination of photons and neutrons in liquid organic scinitillators. Instead of drawing a decision boundary, each pulse is assigned a photon or neutron confidence probability. This allows for photon and neutron classification on an event-by-event basis. The sum of those confidence probabilities is used to estimate the number of photon and neutron instances in the data. An iterative scheme, similar to an expectation-maximization algorithm for Gaussian mixtures, is used to infer the ratio of photons-to-neutrons in each measurement. Therefore, the probability space adapts to data with varying photon-to-neutron ratios. A time-correlated measurement of Am–Be and separate measurements of 137Cs, 60Co and 232Th photon sources were used to construct libraries of neutrons and photons. These libraries were then used to produce synthetic data sets with varying ratios of photons-to-neutrons. Probability weighted method that we implemented was found to maintain neutron acceptance rate of up to 90% up to photon-to-neutron ratio of 2000, and performed 9% better than the decision boundary approach. Furthermore, the iterative approach appropriately changed the probability space with an increasing number of photons which kept the neutron population estimate from unrealistically increasing

  15. Comparison of pulse propagation and gain saturation characteristics among different input pulse shapes in semiconductor optical amplifiers

    Science.gov (United States)

    Barua, Suchi; Das, Narottam; Nordholm, Sven; Razaghi, Mohammad

    2016-01-01

    This paper presents the pulse propagation and gain saturation characteristics for different input optical pulse shapes with different energy levels in semiconductor optical amplifiers (SOAs). A finite-difference beam propagation method (FD-BPM) is used to solve the modified nonlinear Schrödinger equation (MNLSE) for the simulation of nonlinear optical pulse propagation and gain saturation characteristics in the SOAs. In this MNLSE, the gain spectrum dynamics, gain saturation are taken into account those are depend on the carrier depletion, carrier heating, spectral hole-burning, group velocity dispersion, self-phase modulation and two photon absorption. From this simulation, we obtained the output waveforms and spectra for different input pulse shapes considering different input energy levels. It has shown that the output pulse shape has changed due to the variation of input parameters, such as input pulse shape, input pulse width, and input pulse energy levels. It also shown clearly that the peak position of the output waveforms are shifted toward the leading edge which is due to the gain saturation of the SOA. We also compared the gain saturation characteristics in the SOA for different input pulse shapes.

  16. Optical micromanipulation using dispersion-compensated and phase-shaped ultrashort pulsed lasers

    OpenAIRE

    Shane, Janelle

    2009-01-01

    Ultrashort pulsed lasers offer high peak powers at low average powers, making them ideal for maximising the efficiency of nonlinear excitation. Their broad bandwidths make it possible to tailor the pulse's temporal profile for advanced control of multiphoton excitation, techniques known as pulse shaping. This thesis represents the first combination of ultrashort pulse shaping with optical trapping and axicon dispersion compensation. We construct an optical trapping system which incorpora...

  17. Automatic detection and elimination of periodic pulse shaped interferences in partial discharge measurements

    OpenAIRE

    Nagesh, V.; Gururaj, BI

    1994-01-01

    The interferences present in partial discharge (PD) measurement can be classified as narrow-band and broad-band, the latter being pulsed shaped. The pulse shaped interferences can be periodic or random with respect to power frequency, the former being very common and strong. The paper describes an algorithm for automatic detection and elimination of periodic pulse shaped interferences in PD measurements. The algorithm is developed on lines similar to that used in decomposing an electromyogram...

  18. 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...

  19. 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.

  20. 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.

  1. Optical fibre digital pulse-position-modulation assuming a Gaussian received pulse shape

    OpenAIRE

    Cryan, R.A.; Unwin, Rodney T.; Garrett, Ian; Sibley, Martin J.N.; Calvert, N.M.

    1990-01-01

    The abundance in bandwidth available in the best monomode fibres may be exchanged for improved receiver sensitivity by employing digital PPM. The paper presents a performance and optimisation analysis for a digital PPM coding scheme operating over a fibre channel employing a PIN-BJT receiver and assuming a Gaussian received pulse shape. The authors present original results for a 50 Mbit/s, 1.3 μm wavelength digital PPM system and conclude that, provided the fibre bandwidth is several times th...

  2. Generation of orthogonal UWB shaping pulses based on compressed chirp signal

    Institute of Scientific and Technical Information of China (English)

    CHE Shu-liang; ZHANG Hong-xin; LU Ying-hua; HE Peng-fei

    2007-01-01

    This study investigates a novel method to numerically generate orthogonal ultrawide band (UWB) shaping pulses based on compressed chirp signal. First, a pulse template with less than 1 ns duration time, which is used to construct a Hermitian matrix, is produced with a compressed chirp pulse. Sub-nanosecond orthogonal pulses are then generated for UWB by using the Hermitian matrix eigenvectors. The simulation results show that the power spectral density distribution of the UWB shaping pulses met the constraint of Federal communications commissions (FCC) spectral mask. The shaping pulses not only have higher spectrum utilization ratio and very short time duration but also have excellent autocorrelation and cross-correlation properties, which is an advantage to reduce the interference between multiusers. Especially, a method to produce sub-nanosecond orthogonal UWB shaping pulses by using a relatively longer duration chirp signal is presented.

  3. 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.

  4. 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.

  5. Pulse shape analysis optimization with segmented HPGe-detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lewandowski, Lars; Birkenbach, Benedikt; Reiter, Peter [Institute for Nuclear Physics, University of Cologne (Germany); Bruyneel, Bart [CEA, Saclay (France); Collaboration: AGATA-Collaboration

    2014-07-01

    Measurements with the position sensitive, highly segmented AGATA HPGe detectors rely on the gamma-ray-tracking GRT technique which allows to determine the interaction point of the individual gamma-rays hitting the detector. GRT is based on a pulse shape analysis PSA of the preamplifier signals from the 36 segments and the central electrode of the detector. The achieved performance and position resolution of the AGATA detector is well within the specifications. However, an unexpected inhomogeneous distribution of interaction points inside the detector volume is observed as a result of the PSA even when the measurement is performed with an isotropically radiating gamma ray source. The clustering of interaction points motivated a study in order to optimize the PSA algorithm or its ingredients. Position resolution results were investigated by including contributions from differential crosstalk of the detector electronics, an improved preamplifier response function and a new time alignment. Moreover the spatial distribution is quantified by employing different χ{sup 2}-minimization procedures.

  6. 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.

  7. 100W fully-fiberised Ytterbium doped master oscillator power amplifier incorporating adaptive pulse shaping

    OpenAIRE

    Lin, Dejiao; Alam, Shaif-ul; Chen, Kangkang; Malinowski, Andrew; Norman, Steve; Richardson, David

    2009-01-01

    We report a pulsed, fully-fiberised, Yb-doped MOPA with a maximum average output power of 100W. Adaptive pulse shaping was incorporated to reduce the impact of nonlinearities, delivering 2mJ flat-topped pulses with 20kW peak power.

  8. Band-selective shaped pulse for high fidelity quantum control in diamond

    OpenAIRE

    Chang, Yan-Chun; Xing, Jian; Zhang, Fei-Hao; Liu, Gang-Qin; Jiang, Qian-Qing; Li, Wu-Xia; Gu, Chang-Zhi; Long, Gui-Lu; Pan, Xin-Yu

    2014-01-01

    High fidelity quantum control over qubits is of crucial importance for realistic quantum computing, and it turns to be more challenging when there are inevitable interactions among qubits. By employing a bandselective shaped pulse, we demonstrate a high fidelity flip over electron spin of nitrogen-vacancy (NV) centers in diamond. In contrast with traditional rectangular pulses, the shaped pulse has almost equal excitation effect among a sharply edged region (in frequency domain). So the three...

  9. Numerical simulations for parabolic pulse shaping in non-linear media

    Science.gov (United States)

    Nora, R. C.; Durfee, C. G.; Carr, L. D.

    2007-03-01

    Pulses with parabolic temporal profiles have the property that they can propagate through non-linear media in a self similar manner. Parabolic pulses have been generated experimentally in fiber amplifiers. Input pulses develop into parabolic pulses by the combined action of group velocity dispersion, non-linear refractive index, and gain. In this work, we are exploring the feasibility of generating ultrafast parabolic pulses in laser resonators. We have successfully numerically simulated the generation of parabolic pulses in fiber amplifiers using two different algorithms, the Cayley method, and fourth order Runge-Kutta, to solve the Nonlinear Schrodinger equation with gain and periodic boundary conditions. In contrast to fiber amplifiers, pulses in laser resonators must maintain a stable pulse shape on each round trip through the optical cavity. We are exploring the prediction that a time dependent saturable gain will stabilize the pulse in the oscillator and yield parabolic pulses.

  10. Experimental cross section of {sup 144}Sm({alpha},{gamma}){sup 148}Gd

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, E. [Atomki, Debrecen (Hungary); Fueloep, Zs. [Atomki, Debrecen (Hungary); Kiss, A.Z. [Atomki, Debrecen (Hungary); Rolfs, C. [Ruhr-Universitaet, Bochum (Germany); Trautvetter, H.-P. [Ruhr-Universitaet, Bochum (Germany); Greife, U. [Ruhr-Universitaet, Bochum (Germany); Junker, M. [Ruhr-Universitaet, Bochum (Germany); Arnould, M. [Universite Libre de Bruxelles, Bruxelles (Belgium); Rayet, M. [Universite Libre de Bruxelles, Bruxelles (Belgium); Oberhummer, H. [Technische Universitaet, Vienna (Austria)

    1997-08-04

    The cross section of the {sup 144}Sm({alpha},{gamma}){sup 148} Gd reaction has been measured in the bombarding energy range of 10.5-13.4 MeV, using activation method based on the off-line {alpha}-activity measurement of the {sup 148}Gd residual nucleus. The long measuring time of the alpha decay demanded the utilization of solid state nuclear track detectors (SSNTD). The first results are compared to the latest statistical model calculations. (orig.).

  11. Wilcoxon signed-rank-based technique for the pulse-shape analysis of HPGe detectors

    Science.gov (United States)

    Martín, S.; Quintana, B.; Barrientos, D.

    2016-07-01

    The characterization of the electric response of segmented-contact high-purity germanium detectors requires scanning systems capable of accurately associating each pulse with the position of the interaction that generated it. This process requires an algorithm sensitive to changes above the electronic noise in the pulse shapes produced at different positions, depending on the resolution of the Ge crystal. In this work, a pulse-shape comparison technique based on the Wilcoxon signed-rank test has been developed. It provides a method to distinguish pulses coming from different interaction points in the germanium crystal. Therefore, this technique is a necessary step for building a reliable pulse-shape database that can be used later for the determination of the position of interaction for γ-ray tracking spectrometry devices such as AGATA, GRETA or GERDA. The method was validated by comparison with a χ2 test using simulated and experimental pulses corresponding to a Broad Energy germanium detector (BEGe).

  12. 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.

  13. 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.

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

    International Nuclear Information System (INIS)

    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

  15. 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.

  16. 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.

  17. Formation of a Mesa Shaped Phonon Pulse in Superfluid 4He

    Science.gov (United States)

    Adamenko, I. N.; Nemchenko, K. E.; Slipko, V. A.

    2010-05-01

    We present a theory for the formation of a mesa shaped phonon pulse in superfluid 4He. Starting from the hydrodynamic equations of superfluid helium, we obtain the system of equations which describe the evolution of strongly anisotropic phonon systems. Such systems can be created experimentally. The solution of the equations are simple waves, which correspond to second sound in the moving phonon pulse. Using these exact solutions, we describe the expansion of phonon pulses in superfluid helium at zero temperature. This theory gives an explanation for the mesa shape observed in the measured phonon angular distributions. Almost all dependencies of the mesa shape on the system parameters can be qualitatively understood.

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

    International Nuclear Information System (INIS)

    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))

  19. 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...

  20. Development of real-time pulse shaping technology in solid-state lasers

    International Nuclear Information System (INIS)

    We developed real-time pulse shaping technology in solid-state lasers for special cutting and welding applications. Our real-time pulse shaping unit has the capabilities of 20 steps variation in laser intensity, 200 steps in laser pulse width, and 16 pulse shape patterns with MOSFET Pulse Width Modulation method. Also, we improved our previous 250 W class Nd:YAG laser system by using this new technology. Many optical parts were localized and lowered much in cost. Only few parts were imported and almost 90% in cost were localized. Also, to accellerate the commercialization by the joint company, the training and transfer of technology were pursued in the joint participation in design and assembly by company researchers from the early stage. Two Nd:YAG lasers have been assembled and will be tested in industrial manufacturing processes to prove the capability of developed Nd:YAG laser with potential users. (Author)

  1. Pulse shaping of on-chip microresonator frequency combs: investigation of temporal coherence

    OpenAIRE

    Chen L; Srinivasan K; Miao H; Leaird D. E.; Ferdous F.; Aksyuk V.; Weiner A. M.

    2013-01-01

    We use pulse shaping to investigate the temporal coherence of frequency combs generated in microresonators pumped by a strong CW laser. We observe that different groups of comb lines have different mutual coherence.

  2. Study of the Pulse Shapes from the 3-in-1 Cards at ATLAS TileCal

    Science.gov (United States)

    Cheng, Y.; Dunford, M.; Kim, Y. K.

    2010-02-01

    The ATLAS Tile Calorimeter (TileCal) is designed to measure energy depositions in a single cell from 30 MeV to 2 TeV, and we expect to calibrate its response to 1-2%. We present studies of pulse shapes from the front-end electronics of the TileCal and infer their impact on minimum bias pile-up events, especially at high luminosity. High and low gain signals were obtained from both CERN and the University of Chicago test benches, using both the charge injection system and LED. In our studies, we quantify pulse-shapes and undershoot, measure card-to-card variations, and then compare these pulse shapes to the reference shapes used in ATLAS simulation. By running the TileCal pulse shape reconstruction using both the standard shapes in simulation and the shapes from test bench measurements, we are able to investigate the sensitivity of the reconstruction procedure to differences in pulse shape. )

  3. High-purity germanium detector ionization pulse shapes of nuclear recoils, gamma interactions and microphonism

    OpenAIRE

    Baudis, L.; Hellmig, J.; Klapdor-Kleingrothaus, H. V.; Ramachers, Y.; Hammer, J. W.; Mayer, A.

    1999-01-01

    Nuclear recoil measurements with high-purity Germanium detectors are very promising to directly detect dark matter candidates. The main background sources in such experiments are natural radioactivity and microphonic noise. Digital pulse shape analysis is an encouraging approach to reduce the background originating from the latter. To study the pulse shapes of nuclear recoil events we performed a neutron scattering experiment, which covered the ionization energy range from 20 to 80 keV. We ha...

  4. 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.

  5. 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...

  6. 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...

  7. Ionization of H Rydberg atoms by microwaves: Pulse-shape influence on the algebraic decay

    Energy Technology Data Exchange (ETDEWEB)

    Gebarowski, R.; Zakrzewski, J. (Instytut Fizyki Uniwersytetu Jagiellonskiego, ulica Reymonta 4, 30-059 Krakow (Poland))

    1994-11-01

    A classical study is performed of the ionization of hydrogen Rydberg atoms by [ital circularly] polarized microwaves. It is shown that the electron survival probability may decay algebraically for long microwave pulses. The character of the decay is sensitive to the initial atomic state as well as to the assumed shape of the microwave pulse.

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

    International Nuclear Information System (INIS)

    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

  9. 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.

  10. 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.

  11. Theoretical framework for mapping pulse shapes in semiconductor radiation detectors

    CERN Document Server

    Prettyman, T H

    1999-01-01

    An efficient method for calculating of charge pulses produced by semiconductor detectors is presented. The method is based on a quasi-steady-state model for semiconductor detector operation. A complete description of the model and underlying assumptions is given. Mapping of charge pulses is accomplished by solving an adjoint carrier continuity equation. The solution of the adjoint equation yields Green's function, a time- and position-dependent map that contains all possible charge pulses that can be produced by the detector for charge generated at discrete locations (e.g., by gamma-ray interactions). Because the map is generated by solving a single, time-dependent problem, the potential for reduction in computational effort over direct mapping methods is significant, particularly for detectors with complex electrode structures. In this paper, the adjoint equation is presented and the mapping method is validated for a benchmark problem.

  12. Coherent control of bond making: The performance of rationally phase-shaped femtosecond laser pulses

    CERN Document Server

    Levin, Liat; Kosloff, Ronnie; Koch, Christiane P; Amitay, Zohar

    2015-01-01

    The first step in the coherent control of a photoinduced binary reaction is bond making or photoassociation. We have recently demonstrated coherent control of bond making in multi-photon femtosecond photoassociation of hot magnesium atoms, using linearly chirped pulses [Levin et al., arXiv:1411.1542]. The detected yield of photoassociated magnesium dimers was enhanced by positively chirped pulses which is explained theoretically by a combination of purification and chirp-dependent Raman transitions. The yield could be further enhanced by pulse optimization resulting in pulses with an effective linear chirp and a sub-pulse structure, where the latter allows for exploiting vibrational coherences. Here, we systematically explore the efficiency of phase-shaped pulses for the coherent control of bond making, employing a parametrization of the spectral phases in the form of cosine functions. We find up to an order of magnitude enhancement of the yield compared to the unshaped transform-limited pulse. The highly per...

  13. 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.

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

    OpenAIRE

    Jörg Körner; Jürgen Reiter; Joachim Hein; Kaluza, Malte C.

    2015-01-01

    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 distr...

  15. First direct measurement of resonance strengths in 17O({\\alpha}, {\\gamma})21Ne

    CERN Document Server

    Best, A; Couder, M; deBoer, R; Falahat, S; Kontos, A; LeBlanc, P J; Li, Q; O'Brien, S; Sonnabend, K; Talwar, R; Uberseder, E; Wiescher, M

    2011-01-01

    The reaction 17O({\\alpha},{\\gamma})21Ne has been measured by in-beam gamma spectroscopy for the first time in the energy range E{\\alpha} = 750 keV to 1650 keV using highly enriched anodized Ta2(17O)5 targets. Resonances were found at E({\\alpha}) = 1002 keV, 1386 keV and 1619 keV. Their strengths and primary gamma-ray branchings are given. The new results exclude the low reaction rate of Descouvemont and support the rate of Caughlan and Fowler. Implications for the neutron poisoning efficiency of 16O in the weak s process are discussed.

  16. 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 ...

  17. 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.

  18. Femtosecond laser microchannels fabrication based on electrons dynamics control using temporally or spatially shaped pulses

    Science.gov (United States)

    Yan, Xueliang; Hu, Jie; Li, Xiaowei; Xia, Bo; Liu, Pengjun; Lu, Yongfeng; Jiang, Lan

    2014-11-01

    With ultrashort pulse durations and ultrahigh power densities, femtosecond laser presents unique advantages of high precision and high quality fabrication of microchannels in transparent materials. In our study, by shaping femtosecond laser pulse energy distribution in temporal or spatial domains, localized transient electrons dynamics and the subsequent processes, such as phase changes, can be controlled, leading to the dramatic increases in the capability of femtosecond laser microchannels fabrication. The temporally shaped femtosecond laser pulse trains can significantly enhance the material removal rate in both water-assisted femtosecond laser drilling and femtosecond laser irradiation followed by chemical etching. Besides, high-aspect-ratio and small-diameter microchannels are drilled by spatially shaped femtosecond laser pulses.

  19. Band-selective shaped pulse for high fidelity quantum control in diamond

    International Nuclear Information System (INIS)

    High fidelity quantum control of qubits is crucially important for realistic quantum computing, and it becomes more challenging when there are inevitable interactions between qubits. We introduce a band-selective shaped pulse, refocusing BURP (REBURP) pulse, to cope with the problems. The electron spin of nitrogen-vacancy centers in diamond is flipped with high fidelity by the REBURP pulse. In contrast with traditional rectangular pulses, the shaped pulse has almost equal excitation effect in a sharply edged region (in frequency domain). So the three sublevels of host 14N nuclear spin can be flipped accurately simultaneously, while unwanted excitations of other sublevels (e.g., of a nearby 13C nuclear spin) is well suppressed. Our scheme can be used for various applications such as quantum metrology, quantum sensing, and quantum information process.

  20. Band-selective shaped pulse for high fidelity quantum control in diamond

    Science.gov (United States)

    Chang, Yan-Chun; Xing, Jian; Zhang, Fei-Hao; Liu, Gang-Qin; Jiang, Qian-Qing; Li, Wu-Xia; Gu, Chang-Zhi; Long, Gui-Lu; Pan, Xin-Yu

    2014-06-01

    High fidelity quantum control of qubits is crucially important for realistic quantum computing, and it becomes more challenging when there are inevitable interactions between qubits. We introduce a band-selective shaped pulse, refocusing BURP (REBURP) pulse, to cope with the problems. The electron spin of nitrogen-vacancy centers in diamond is flipped with high fidelity by the REBURP pulse. In contrast with traditional rectangular pulses, the shaped pulse has almost equal excitation effect in a sharply edged region (in frequency domain). So the three sublevels of host 14N nuclear spin can be flipped accurately simultaneously, while unwanted excitations of other sublevels (e.g., of a nearby 13C nuclear spin) is well suppressed. Our scheme can be used for various applications such as quantum metrology, quantum sensing, and quantum information process.

  1. Band-selective shaped pulse for high fidelity quantum control in diamond

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yan-Chun; Xing, Jian; Liu, Gang-Qin; Jiang, Qian-Qing; Li, Wu-Xia [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Zhang, Fei-Hao [Tsinghua National Laboratory for Information Science and Technology, Beijing 100084 (China); State Key Laboratory of Low-Dimensional Physics and Department of Physics, Tsinghua University, Beijing 100084 (China); Gu, Chang-Zhi; Pan, Xin-Yu, E-mail: xypan@aphy.iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100871 (China); Long, Gui-Lu [Tsinghua National Laboratory for Information Science and Technology, Beijing 100084 (China); State Key Laboratory of Low-Dimensional Physics and Department of Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100871 (China)

    2014-06-30

    High fidelity quantum control of qubits is crucially important for realistic quantum computing, and it becomes more challenging when there are inevitable interactions between qubits. We introduce a band-selective shaped pulse, refocusing BURP (REBURP) pulse, to cope with the problems. The electron spin of nitrogen-vacancy centers in diamond is flipped with high fidelity by the REBURP pulse. In contrast with traditional rectangular pulses, the shaped pulse has almost equal excitation effect in a sharply edged region (in frequency domain). So the three sublevels of host {sup 14}N nuclear spin can be flipped accurately simultaneously, while unwanted excitations of other sublevels (e.g., of a nearby {sup 13}C nuclear spin) is well suppressed. Our scheme can be used for various applications such as quantum metrology, quantum sensing, and quantum information process.

  2. 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.

  3. 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....

  4. Analysis of pulse shape from a high-resolution superconducting tunnel junction X-ray spectrometer

    International Nuclear Information System (INIS)

    Superconducting-insulating-superconducting (SIS) tunnel junctions coupled to superconducting absorbers may be used as high-resolution, high-efficiency X-ray spectrometers. Until recently, the X-ray-induced current pulse from such devices has been measured using FET-based negative-feedback charge or current amplifiers. The limited bandwidth and feed-back nature of these amplifiers have made it difficult to deduce the true shape of the X-ray induced current pulse. Recently, we have begun to use high-bandwidth amplifiers based on Superconducting Quantum Interference Devices (SQUIDS) to measure the current pulses from our tunnel junction X-ray spectrometers. We have measured pulses from devices with niobium X-ray absorbing layers coupled to aluminum layers that serve as quasiparticle traps. We present here a study of pulse shape as a function of bias voltage. In general, the X-ray induced pulses increase in amplitude and become longer as we increase the bias voltage. We found that it is possible to differentiate pulses produced by X-ray absorption in the top niobium film from those produced in the bottom niobium film by measuring the rise time of the current pulses. This allows us to produce a high resolution spectrum using only pulses produced in the bottom niobium film. The measured energy resolution of this spectrum is 29 eV FWHM at 5.89 keV, about 5 times better than that obtainable using semiconductor ionization detectors. (orig.)

  5. 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.

  6. Pulse shaping to improve performance of NMR multiple-pulse sequences: 2-D solvent-suppressed cosy of vitamin B 1 in water

    Science.gov (United States)

    McCoy, Mark; Warren, Warren S.

    1987-01-01

    Grafted "narrow reject" pulse shapes, whicch were shown previously to be capable of uniformly exciting a wide range of resonance frequencies with a sharp null directly on resonance for solvent suppression, are combined to generate multiple-pulse sequences. In particular, we show that two-dimensional solvent-suppressed spectra can be obtained with such pulses. This is the first application of pulse Grafting to high-resolution, multiple-pulse NMR spectroscopy.

  7. Neutron generator burst timing measured using a pulse shape discrimination plastic scintillator with silicon photomultiplier readout

    Science.gov (United States)

    Preston, R. M.; Eberhardt, J. E.; Tickner, J. R.

    2013-12-01

    An EJ-299-34 plastic scintillator with silicon photomultiplier (SiPM) readout was used to measure the fast neutron output of a pulsed Thermo-Fisher A-325 Deuterium-Tritium sealed tube neutron generator (STNG). The SiPM signals were handled by a prototype digital pulse processing system, based on a free-running analogue to digital converter feeding a digital signal processor (DSP). Pulse shape discrimination was used to distinguish between detected fast-neutrons and gammas. Pulse detection, timing, energy and shape were all processed by the DSP in real-time. The time-dependency of the neutron output of the STNG was measured for various pulsing schemes. The switch-on characteristics of the tube strongly depended on the operating settings, with the delay between pulse turn-on and the production of neutrons ranging between 13 μs to 74 μs for the tested pulse rates and duty cycles. This work will facilitate the optimization and modeling of apparatus that use the neutron generator's pulsing abilities.

  8. 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.

  9. 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.

  10. Simultaneous ballistic deficit immunity and resilience to parallel noise sources: A new pulse shaping technique

    Energy Technology Data Exchange (ETDEWEB)

    Fabris, Lorenzo; Becker, John A.; Goulding, Frederick S.; Madden, Norman W.

    2000-10-11

    A new and different time variant pulse processing system has been developed based on a simple CR-RC filter and two analog switches. The new pulse processing technique combines both ballistic deficit immunity and resilience to parallel noise without a significant compromise to the low energy resolution, generally considered a mutually exclusive requirement. The filter is realized by combining two different pulse-shaping techniques. One of the techniques creates a low rate of curvature at the pulse peak, which reduces ballistic deficit, while the second technique increases the tolerance to low frequency noise by modifying the noise history. Several experimental measurements are presented, including tests on a co-planar grid CdZnTe detector. Improvements on both the resolution and line shape are shown for the 662 keV line of 137Cs.

  11. Study of neutron-gamma pulse shape discrimination algorithms for scintillation detector

    International Nuclear Information System (INIS)

    Differentiating pulse of neutron and gamma is one of the important problem in measurements neutron spectrometry using the scintillation detector. This paper presents the research results of neutron-gamma pulse shape discrimination for an NE213 liquid scintillation detectors. From the data simulation software MatLab, four algorithms neutron-gamma pulse shape discrimination were studied. The results obtained show that method for rise-time discrimination has quality factor (Figure of-Merits: FOM=1.09), pulsed gradient analysis method (FOM=0.66), charge comparison method (FOM =2.21), and correlation pattern method (FOM = 1.97). This result is the basis for building systems used measurements neutron by scintillation detectors. (author)

  12. Simultaneous ballistic deficit immunity and resilience to parallel noise sources: A new pulse shaping technique

    International Nuclear Information System (INIS)

    A new and different time variant pulse processing system has been developed based on a simple CR-RC filter and two analog switches. The new pulse processing technique combines both ballistic deficit immunity and resilience to parallel noise without a significant compromise to the low energy resolution, generally considered a mutually exclusive requirement. The filter is realized by combining two different pulse-shaping techniques. One of the techniques creates a low rate of curvature at the pulse peak, which reduces ballistic deficit, while the second technique increases the tolerance to low frequency noise by modifying the noise history. Several experimental measurements are presented, including tests on a co-planar grid CdZnTe detector. Improvements on both the resolution and line shape are shown for the 662 keV line of 137Cs

  13. Key technology research of nuclear signal digitized pulse shaping in real time

    International Nuclear Information System (INIS)

    The computer simulation and analysis were carried out for the ideal nuclear pulse signal and the actual detector output signals, and the determination method of digital trapezoidal shape parameter for different nuclear pulse shaping time was summarized. At high count rate measurement occasion, the effective count rate is increased, some pile-up pulses are eliminated and the accumulation of dead time of the system is reduced. Meanwhile, Si-PIN semiconductor detector performance was tested by 256 points and 512 points digital triangle forming methods and the analog circuit forming methods for comparative tests. Test results show that the pulse forming treatment method increases the count rate performance and the resolution of detector. (authors)

  14. Pulse Shape Analysis with a Broad-Energy Germanium Detector for the GERDA experiment

    CERN Document Server

    Budjá?, Du?an; Chkvorets, Oleg; Schönert, Stefan; Khanbekov, Nikita

    2008-01-01

    To reduce background in experiments looking for rare events, such as the GERDA double beta decay experiment, it is necessary to employ active background-suppression techniques. One of such techniques is the pulse shape analysis of signals induced by the interaction of radiation with the detector. Analysis of the time-development of the impulses can distinguish between an interaction of an electron and an interaction of a multiple-scattered photon inside the detector. This information can be used to eliminate background events from the recorded data. Results of pulse-shape analysis of signals from a commercially available broad-energy germanium detector are presented and the pulse-shape discrimination capability of such detector configuration for use in low-background experiments is discussed.

  15. 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)].

  16. 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.

  17. PAPR reduction based on improved Nyquist pulse shaping technology in OFDM-RoF systems

    Science.gov (United States)

    Liu, Jian-fei; Li, Ning; Lu, Jia; Zeng, Xiang-ye; Li, Jie; Wang, Meng-jun

    2013-01-01

    High peak-to-average power ratio (PAPR) is the main disadvantage in orthogonal frequency-division multiplexing (OFDM) communication systems, which also exists in OFDM-radio over fiber (RoF) systems. In this paper, we firstly analyze the impact of high PAPR on a 40 GHz OFDM-RoF system, and then describe the theory of Nyquist pulse shaping technology for reducing PAPR. To suppress PAPR further, an improved Nyquist pulse shaping technology is proposed, in which the distribution of original-data amplitude is changed by properly selecting the time-limited waveforms of the different subcarriers. We firstly apply the improved Nyquist pulse shaping technology to an OFDM-RoF system. The simulation results show that PAPR is effectively reduced by more than 2 dB with the bit error rate (BER) declining by about 0.125%.

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

    International Nuclear Information System (INIS)

    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-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.

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

    International Nuclear Information System (INIS)

    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.

  20. 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

  1. Pulse shaping via forward second harmonic generation in nonlinear photonic crystals

    International Nuclear Information System (INIS)

    We have theoretically designed a method for obtaining short laser pulses by second harmonic generation in periodically and aperiodically poled quadratic nonlinear photonic crystals. An efficient algorithm is developed to construct quasi-phase matching gratings which allow one to shape the required amplitude and phase of second-harmonic pulses considering energy exchange. Developed method could be applied for designing of nonlinear photonic crystals. (authors)

  2. 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.

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

    International Nuclear Information System (INIS)

    This paper describes a rep-rated multibeam KrF laser driver design for the 500 kJ 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 ∼4 MW/cm2 saturation levels associated with quasi-cw operation; i.e., they show that KrF can act as a storage medium even for pulsewidths of ∼1 ns. 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 428 kJ, a peak spike power of 385 TW, and amplified spontaneous emission prepulse contrast ratios IASE/I-7 in intensity and FASE/F-5 in fluence. Finally, the paper proposes a front-end pulse shaping technique that combines an optical Kerr gate with cw 248 nm light and a 1 μm control beam shaped by advanced fiber optic technology, such as the one used in the National Ignition Facility (NIF) laser.

  4. 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. PMID:24913424

  5. 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.

  6. 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....

  7. 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.

  8. Model-based pulse shape correction for CdTe detectors

    Science.gov (United States)

    Bargholtz, Chr.; Fumero, E.; Mårtensson, L.

    1999-02-01

    We present a systematic method to improve energy resolution of CdTe-detector systems with full control of the efficiency. Sampled pulses and multiple amplifier data are fitted by a model of the pulse shape including the deposited energy and the interaction point within the detector as parameters. We show the decisive improvements of spectral resolution and photo-peak efficiency that is obtained without distortion of spectral shape. The information concerning the interaction depth of individual events can be used to discriminate between beta particles and gamma quanta.

  9. Pulse shape effects on photon-photon interactions in non-linear optical quantum gates

    OpenAIRE

    Hofmann, Holger F.; Nishitani, Hitoshi

    2009-01-01

    Ideally, strong non-linearities could be used to implement quantum gates for photonic qubits by well controlled two photon interactions. However, the dependence of the non-linear interaction on frequency and time makes it difficult to preserve a coherent pulse shape that could justify a single mode model for the time-frequency degree of freedom of the photons. In this paper, we analyze the problem of temporal multi-mode effects by considering the pulse shape of the average output field obtain...

  10. Model-based pulse shape correction for CdTe detectors

    CERN Document Server

    Bargholtz, C; Maartensson, L

    1999-01-01

    We present a systematic method to improve energy resolution of CdTe-detector systems with full control of the efficiency. Sampled pulses and multiple amplifier data are fitted by a model of the pulse shape including the deposited energy and the interaction point within the detector as parameters. We show the decisive improvements of spectral resolution and photo-peak efficiency that is obtained without distortion of spectral shape. The information concerning the interaction depth of individual events can be used to discriminate between beta particles and gamma quanta. (author)

  11. 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.

  12. 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.

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

    Science.gov (United States)

    Wang, Chun-Li; Yang, Yueh-Lung; Wu, Wen-Hsiang; Tsai, Tung-Hu; Chang, Hen-Hong

    2016-01-01

    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 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. PMID:27304979

  14. 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...... electronic state. Now, applying pulse shaping via the modulation of the phases of each spectral component of an ultrashort pulse, it is tempting to ask whether it is also possible to induce instantaneous nonvertical transitions to bound electronic states, provided that the phases of each spectral component...

  15. 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.

  16. Controlling pathway dynamics of a four-level quantum system with pulse shaping

    Science.gov (United States)

    Cao, Dewen; Yang, Ling; Wang, Yaoxiong; Shuang, Feng; Gao, Fang

    2016-07-01

    The dynamics of two two-photon absorption (TPA) pathways in a four-level quantum system driven by a laser pulse is investigated in this work. An analytical solution for pulse shaping is proposed to be globally optimal for constructive interference between the two pathways, and accurate spectral boundaries for phase modulation are obtained. The TPA rate can be enhanced by a factor of 8.33 with the optimal pulse instead of the transform limited pulse (TL pulse). Simple control strategies modulating both amplitudes and phases are also designed to increase the TPA amplitude along one pathway while decreasing that along the other simultaneously. The strategies are intuitive and the two pathway amplitudes can differ by two orders of magnitude.

  17. Excitation of a single atom with a temporaly shaped light pulses

    Science.gov (United States)

    Maslennikov, Gleb; Aljunid, Syed; Hoang Lan, Dao; Durak, Kadir; Leong, Victor; Kurtsiefer, Christian

    2012-06-01

    We investigate the interaction between a single atom and coherent optical pulses with a controlled temporal envelope. By switching the temporal shape from rising exponential to square profile, we show that the rising exponential envelope leads to higher excitation probability using lower photon number in a pulse. The atomic transition saturates for 100 photons in a pulse. Rabi oscillations with 100,Hz frequency are visible in detected fluorescence for excitations powers of 1300 photons in a 15,s pulse. A possibility to excite the atom with pulses in a Fock states is discussed and the theoretical treatment is presented. [4pt] [1] Yimin Wang et al., Phys. Rev. A. 83 063842 (2011)[0pt] [2] M. Stobinska et al., EPL 86 14007 (2009)[0pt] [3] I. Gerhardt et al., Phys. Rev. A 79 011402(R) (2009)

  18. 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.

  19. Pulsed plane wave analytic solutions for generic shapes and the validation of Maxwell's equations solvers

    Science.gov (United States)

    Yarrow, Maurice; Vastano, John A.; Lomax, Harvard

    1992-01-01

    Generic shapes are subjected to pulsed plane waves of arbitrary shape. The resulting scattered electromagnetic fields are determined analytically. These fields are then computed efficiently at field locations for which numerically determined EM fields are required. Of particular interest are the pulsed waveform shapes typically utilized by radar systems. The results can be used to validate the accuracy of finite difference time domain Maxwell's equations solvers. A two-dimensional solver which is second- and fourth-order accurate in space and fourth-order accurate in time is examined. Dielectric media properties are modeled by a ramping technique which simplifies the associated gridding of body shapes. The attributes of the ramping technique are evaluated by comparison with the analytic solutions.

  20. 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.

  1. Precision neutron flux measurements and applications using the Alpha Gamma device

    Science.gov (United States)

    Anderson, Eamon

    2016-03-01

    The Alpha Gamma device is a totally-absorbing 10 B neutron detector designed to measure the absolute detection efficiency of a thin-film lithium neutron monitor on a monoenergetic neutron beam. The detector has been shown to measure neutron fluence with an absolute accuracy of 0.06%. This capability has been used to perform the first direct, absolute measurement of the 6Li(n,t) 4He cross section at sub-thermal energy, improve the neutron fluence determination in a past beam neutron lifetime measurement by a factor of five, and is being used to calibrate the neutron monitors for use in the upcoming beam neutron lifetime measurement BL2 (NIST Beam Lifetime 2). The principle of the measurement method will presented and the applications will be discussed. We would like to acknowledge support of this research through the NSF-PHY-1068712 Grant as well as the NIST Precision Measurement Grant program.

  2. Second harmonic generation and pulse shaping in positively and negatively spatially dispersive nanowaveguides: comparative analysis

    CERN Document Server

    Popov, Alexander K

    2015-01-01

    Comparative analysis of second harmonic generation in ordinary and backward-wave settings is presented. Extraordinary properties of frequency doubling nonlinear optical reflectivity and pulse shaping through phase matching of ordinary and backward electromagnetic waves in the nanowaveguides with mixed negative/positive spatial dispersion is demonstrated with numerical simulations.

  3. 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.

  4. Average pulse shape model for leading edge timing with Ge(Li) coaxial detector

    International Nuclear Information System (INIS)

    A model is presented for prompt time-response from leading-edge triggering, where calculations are rendered simpler for uniform γ-irradiation of coaxial Ge(Li) detector. Pulse shapes are formed at the timing filter amplifier output, from direct detector pulse. Average pulse-shape method is found responsible for some sort of walk compensation and by drawing time-resolution vs triggering fraction, one can predict the best FWHM with detector of RC-filtered signal. It also shows the effect of mixed filter time-constant on r.m.s. noise. Taking account of both statistical and noise effects on FWHM, the statistical contribution increases to 7% at 3 MeV of the detected energy

  5. 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.

  6. 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).

  7. 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.

  8. 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.

  9. 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.

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

    Science.gov (United States)

    McFee, J. E.; Mosquera, C. M.; Faust, A. A.

    2016-08-01

    An analysis of digitized pulse waveforms from experiments with LaBr3(Ce) and LaCl3(Ce) detectors is presented. Pulse waveforms from both scintillator types were captured in the presence of 22Na and 60Co 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 LaCl3(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. LaBr3(Ce) waveforms had a single decay component and showed no ability for alpha/electron PSD. LaCl3(Ce) was observed to have short and long decay components and alpha/electron discrimination was observed.

  11. 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.

  12. Coherent control of atoms and diatomic molecules with shaped ultrashort pulses

    International Nuclear Information System (INIS)

    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)

  13. 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. PMID:18648449

  14. Shock Pulse Shaping in a Small-Form Factor Velocity Amplifier

    Directory of Open Access Journals (Sweden)

    Gerard Kelly

    2010-01-01

    Full Text Available This theme of this paper is the design and characterisation of a velocity amplifier (VAMP machine for high-acceleration shock testing of micro-scale devices. The VAMP applies multiple sequential impacts to amplify velocity through a system of three progressively smaller masses constrained to move in the vertical axis. Repeatable, controlled, mechanical shock pulses are created through the metal-on-metal impact between pulse shaping test rods, which form part of the penultimate and ultimate masses. The objectives are to investigate the controllable parameters that affect the shock pulses induced on collision, namely; striker and incident test rod material; test rod length; pulse shaping mechanisms; and impact velocity. The optimum VAMP configuration was established as a 60 mm long titanium striker test rod and a 120 mm long titanium incident rod. This configuration exhibited an acceleration magnitude and a primary pulse duration range of 5,800–23,400 g and 28.0–44.0 μs respectively. It was illustrated that the acceleration spectral content can be manipulated through control of the test rod material and length. This is critical in the context of practical applications, where it is postulated that the acceleration signal can be controlled to effectively excite specific components in a multi-component assembly affixed to the VAMP incident test rod.

  15. 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. PMID:26851823

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

    Energy Technology Data Exchange (ETDEWEB)

    Dighe, P.M., E-mail: pmdighe@barc.gov.in; 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 4.5×10{sup 4} 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.

  17. Pulse shape analysis with a broad-energy germanium detector for the gerda experiment

    International Nuclear Information System (INIS)

    To reduce background in experiments looking for rare events, such as the GERDA double beta decay experiment, it is necessary to employ active background-suppression techniques. One of such techniques is the pulse shape analysis of signals induced by the interaction of radiation with the detector. Analysis of the time-development of the impulses can distinguish between an interaction of an electron and an interaction of a multiple-scattered photon inside the detector. This information can be used to eliminate unwanted events from the recorded data. In this talk, results of a pulse-shape analysis of signals from a commercially available broad-energy germanium detector will be presented. The background rejection capability of such detector configuration and the potential for its use in ultralow-background experiments are discussed.

  18. 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.

  19. Pulse shape analysis and position determination in segmented HPGe detectors: The AGATA detector library

    Energy Technology Data Exchange (ETDEWEB)

    Bruyneel, B. [Universitaet zu Koeln, Institut fuer Kernphysik, Koeln (Germany); Service de Physique Nucleaire, CEA Saclay, Gif-sur-Yvette (France); Birkenbach, B.; Reiter, P. [Universitaet zu Koeln, Institut fuer Kernphysik, Koeln (Germany)

    2016-03-15

    The AGATA Detector Library (ADL) was developed for the calculation of signals from highly segmented large volume high-purity germanium (HPGe) detectors. ADL basis sets comprise a huge amount of calculated position-dependent detector pulse shapes. A basis set is needed for Pulse Shape Analysis (PSA). By means of PSA the interaction position of a γ -ray inside the active detector volume is determined. Theoretical concepts of the calculations are introduced and cover the relevant aspects of signal formation in HPGe. The approximations and the realization of the computer code with its input parameters are explained in detail. ADL is a versatile and modular computer code; new detectors can be implemented in this library. Measured position resolutions of the AGATA detectors based on ADL are discussed. (orig.)

  20. Pulse shape analysis and position determination in segmented HPGe detectors: The AGATA detector library

    Science.gov (United States)

    Bruyneel, B.; Birkenbach, B.; Reiter, P.

    2016-03-01

    The AGATA Detector Library (ADL) was developed for the calculation of signals from highly segmented large volume high-purity germanium (HPGe) detectors. ADL basis sets comprise a huge amount of calculated position-dependent detector pulse shapes. A basis set is needed for Pulse Shape Analysis (PSA). By means of PSA the interaction position of a γ-ray inside the active detector volume is determined. Theoretical concepts of the calculations are introduced and cover the relevant aspects of signal formation in HPGe. The approximations and the realization of the computer code with its input parameters are explained in detail. ADL is a versatile and modular computer code; new detectors can be implemented in this library. Measured position resolutions of the AGATA detectors based on ADL are discussed.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Boron-loaded plastic scintillator with neutron-γ pulse shape discrimination capability

    Energy Technology Data Exchange (ETDEWEB)

    Pawełczak, I.A., E-mail: pawelczak1@llnl.gov; Glenn, A.M.; Martinez, H.P.; Carman, M.L.; Zaitseva, N.P.; Payne, S.A.

    2014-07-01

    Development of the plastic scintillator with neutron sensitivity from thermal to multi-MeV and pulse shape discrimination (PSD) has been demonstrated. Incorporation of {sup 10}B-containing compounds into the plastic scintillator with PSD capability leads to detector improvement in regard to neutron detection efficiency while preserving the discrimination between neutrons and γ-rays. Effects of boron loading on scintillation and pulse shape discrimination properties are discussed. A PSD figure-of-merit value of 1.4±0.03 has been achieved for events in a thermal neutron energy domain, 50–100 keV{sub ee}, for PSD plastic loaded with 5 wt.% of m-carborane.

  6. Pulse shape analysis and position determination in segmented HPGe detectors: The AGATA detector library

    International Nuclear Information System (INIS)

    The AGATA Detector Library (ADL) was developed for the calculation of signals from highly segmented large volume high-purity germanium (HPGe) detectors. ADL basis sets comprise a huge amount of calculated position-dependent detector pulse shapes. A basis set is needed for Pulse Shape Analysis (PSA). By means of PSA the interaction position of a γ -ray inside the active detector volume is determined. Theoretical concepts of the calculations are introduced and cover the relevant aspects of signal formation in HPGe. The approximations and the realization of the computer code with its input parameters are explained in detail. ADL is a versatile and modular computer code; new detectors can be implemented in this library. Measured position resolutions of the AGATA detectors based on ADL are discussed. (orig.)

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

    Science.gov (United States)

    Kavrigin, P.; Finocchiaro, P.; Griesmayer, E.; Jericha, E.; Pappalardo, A.; Weiss, C.

    2015-09-01

    A novel technique for the rejection of gamma background from charged-particle spectra was demonstrated using a CVD diamond detector with a 6Li 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 6Li(n,T)4He thermal neutron capture reaction were separated from the gamma background by a new algorithm based on pulse-shape analysis. The thermal neutron capture in 6Li 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. 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.

  9. 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

  10. Pulse shape dependence in the dynamically assisted Sauter-Schwinger effect

    Science.gov (United States)

    Linder, Malte F.; Schneider, Christian; Sicking, Joachim; Szpak, Nikodem; Schützhold, Ralf

    2015-10-01

    While the Sauter-Schwinger effect describes nonperturbative electron-positron pair creation from vacuum by a strong and slowly varying electric field Estrong via tunneling, the dynamically assisted Sauter-Schwinger effect corresponds to a strong (exponential) enhancement of the pair-creation probability by an additional weak and fast electric or electromagnetic pulse Eweak. Using the WKB and worldline instanton method, we find that this enhancement mechanism strongly depends on the shape of the fast pulse. For the Sauter profile 1 /cosh2(ω t ) considered previously, the threshold frequency ωcrit (where the enhancement mechanism sets in) is basically independent of the magnitude Eweak of the weak pulse—whereas for a Gaussian pulse exp (-ω2t2), an oscillating profile cos (ω t ) or a standing wave cos (ω t )cos (k x ) , the value of ωcrit does depend (logarithmically) on Eweak/Estrong.

  11. Trapped field and temperature rise in rectangular-shaped HTSC bulk magnetized by pulse fields

    International Nuclear Information System (INIS)

    A rectangular-shaped GdBaCuO bulk (33 x 33 x 20 mm3) has been magnetized by pulse fields with various strengths from Bex = 3 T to 7 T at 44 K and 20 K. The time dependences of the local fields and temperatures have been measured at five positions on the bulk surface. The flux movement, flux trapping and the heat generation are closely related for lower applied fields, i.e., the temperature rise is larger at the specified positions, where a large number of magnetic fluxes are trapped. The heat generation is mainly due to the pinning loss in this condition. The maximum trapped field BT = 4.0 T can be realized on the bulk surface by a modified multi-pulse technique with stepwise cooling (MMPSC) method, on which BT reaches only 2.5 T at 20 K for a single pulse application

  12. 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.

  13. Pulse shape of the self quenching streamer counter in the coexistence region

    International Nuclear Information System (INIS)

    The pulse shape of the electrical signal out of the counter operating in the self-quenching streamer (SQS) mode is obtained and the time correlation between the primary avalanche and the SQS avalanche is measured and studied. The results yield more information in the coexistence region about the time jitters in the process of the SQS avalanche than that shown in our last paper. (orig.)

  14. Growth Inhibition and Membrane Permeabilization of Candida lusitaniae Using Varied Pulse Shape Electroporation

    Directory of Open Access Journals (Sweden)

    V. Novickij

    2015-01-01

    Full Text Available Candida lusitaniae is an opportunistic yeast pathogen, which can readily develop resistance to antifungal compounds and result in a complex long-term treatment. The efficient treatment is difficult since structure and metabolic properties of the fungal cells are similar to those of eukaryotic host. One of the potential methods to improve the inhibition rate or the cell permeability to inhibitors is the application of electroporation. In this work we investigated the dynamics of the growth inhibition and membrane permeabilization of C. lusitaniae by utilizing the various pulse shape and duration electric field pulses. Our results indicated that single electroporation procedure using 8 kV/cm electric field may result in up to 51±5% inhibition rate. Also it has been experimentally shown that the electroporation pulse shape may influence the inhibitory effect; however, the amplitude of the electric field and the pulse energy remain the most important parameters for definition of the treatment outcome. The dynamics of the cell membrane permeabilization in the 2–8 kV/cm electric field were overviewed.

  15. Determination of the 242Pu Branching Ratio via Alpha-Gamma Coincidence

    Energy Technology Data Exchange (ETDEWEB)

    Wang, T F

    2012-05-24

    When the burn-up is high, the {sup 242}Pu isotopic content becomes more important. The traditional correlation method will fail. The {sup 242}Pu isotopic content in the sample plays an essential role if the neutron coincidence method is used to quantify the total amount of plutonium. In one of the earlier measurements we had a chance to measure an isotopic pure (> 99.95 %) {sup 242}Pu thick sample and realized that the difference in the branching ratio (BR) value among current nuclear data3) for the two important gamma-rays at 103.5-keV and 158.8-keV. In this study, the thick sample was counted on a 15% ORTEC safeguards type HPGe to further improve BR determination of the 159-keV gamma-ray. Furthermore, we have made a thin {sup 242}Pu sample from the thick sample and performed alpha-gamma coincidence measurements. Our preliminary gamma-ray BR results are 4.37(6) E-4, 2.79(8) E-5, and 2.25(8) E-6 for 44.9-keV, 103.5-keV, and 158.9-keV, respectively.

  16. Determination of the 242Pu Branching Ratio via Alpha-Gamma Coincidence

    International Nuclear Information System (INIS)

    When the burn-up is high, the 242Pu isotopic content becomes more important. The traditional correlation method will fail. The 242Pu isotopic content in the sample plays an essential role if the neutron coincidence method is used to quantify the total amount of plutonium. In one of the earlier measurements we had a chance to measure an isotopic pure (> 99.95 %) 242Pu thick sample and realized that the difference in the branching ratio (BR) value among current nuclear data3) for the two important gamma-rays at 103.5-keV and 158.8-keV. In this study, the thick sample was counted on a 15% ORTEC safeguards type HPGe to further improve BR determination of the 159-keV gamma-ray. Furthermore, we have made a thin 242Pu sample from the thick sample and performed alpha-gamma coincidence measurements. Our preliminary gamma-ray BR results are 4.37(6) E-4, 2.79(8) E-5, and 2.25(8) E-6 for 44.9-keV, 103.5-keV, and 158.9-keV, respectively.

  17. Pulse shape analysis of enriched BEGe detectors in vacuum cryostat and liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Victoria [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Collaboration: GERDA-Collaboration

    2013-07-01

    The Gerda experiment searches for the lepton number violating neutrinoless double beta (0νββ) decay of {sup 76}Ge. Germanium diodes of BEGe type (Canberra, Belgium) made from isotopically modified material have been procured for Phase II of Gerda. They will improve the sensitivity of the experiment by additional target mass, improved energy resolution and enhanced pulse shape discrimination (PSD) against background events. The PSD efficiencies of the new enriched BEGe detectors were studied in vacuum cryostats as part of the characterization campaign at the HADES underground laboratory. For a deeper understanding of the pulse shape performance of the enriched BEGe detectors, detailed {sup 241}Am surface scans were performed. Unexpectedly high position-dependence of the pulse shape parameter Amplitude-over-Energy was found for some of the detectors. With further investigation this effect was traced to surface charge effects specific to the operational configuration of the detectors inside the vacuum cryostats. The standard behavior is restored when they are operated in liquid argon in the configuration intended for Gerda Phase II. Finally, five of the enriched BEGe diodes were installed in the Gerda liquid argon cryostat prior to the full upgrade. They show a good performance and are able to reject efficiently multi-site-events as well as β- and α-particles.

  18. Root Raised Cosine (RRC) Filters and Pulse Shaping in Communication Systems

    Science.gov (United States)

    Cubukcu, Erkin

    2012-01-01

    This presentation briefly discusses application of the Root Raised Cosine (RRC) pulse shaping in the space telecommunication. Use of the RRC filtering (i.e., pulse shaping) is adopted in commercial communications, such as cellular technology, and used extensively. However, its use in space communication is still relatively new. This will possibly change as the crowding of the frequency spectrum used in the space communication becomes a problem. The two conflicting requirements in telecommunication are the demand for high data rates per channel (or user) and need for more channels, i.e., more users. Theoretically as the channel bandwidth is increased to provide higher data rates the number of channels allocated in a fixed spectrum must be reduced. Tackling these two conflicting requirements at the same time led to the development of the RRC filters. More channels with wider bandwidth might be tightly packed in the frequency spectrum achieving the desired goals. A link model with the RRC filters has been developed and simulated. Using 90% power Bandwidth (BW) measurement definition showed that the RRC filtering might improve spectrum efficiency by more than 75%. Furthermore using the matching RRC filters both in the transmitter and receiver provides the improved Bit Error Rate (BER) performance. In this presentation the theory of three related concepts, namely pulse shaping, Inter Symbol Interference (ISI), and Bandwidth (BW) will be touched upon. Additionally the concept of the RRC filtering and some facts about the RRC filters will be presented

  19. 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.

  20. 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

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

    International Nuclear Information System (INIS)

    Recently, RMD has investigated the use of CLYC (Cs2LiYCl6:Ce), a new and emerging scintillation material, in a gamma–neutron coded aperture imaging system based on RMD's commercial RadCamTM 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 252Cf source was possible using both pulse height and pulse shape discrimination with CLYC. • Imaging with

  2. 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

  3. Martensitic inelasticity of TiNi-shape memory alloy under pulsed loading

    International Nuclear Information System (INIS)

    Some inelastic properties of TiNi shape memory alloy in martensitic state under pulsed loading were investigated. Two millimeter-diameter TiNi wire specimens were subjected to deformation by a magneto-pulsing installation under three-point bending conditions. The dependencies of residual strain on the force amplitude applied to the strikers during eight test series using different mechanical pulse durations from 400 to 1300 μs, were obtained. For each test series the threshold (minimal) value of force impulse amplitude which causes appearance of residual strain was found. Also, the threshold value of stress in each case was calculated using the elastic beam method, the value found to be within the range of 300-900 MPa. In order to describe dynamic mechanical behavior of TiNi shape memory alloy in martensitic state an attempt was made to apply the principles of yielding based on the concept of the so called incubation time. For inelastic deformation the incubation time was calculated based on the data resulting from the above-mentioned experiments. Its value of about 2 ms characterizes the range of occurrence of dynamic properties

  4. 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.)

  5. Fiber optic based heart-rate and pulse pressure shape monitor

    Science.gov (United States)

    Kokkinos, D.; Dehipawala, S.; Holden, T.; Cheung, E.; Musa, M.; Tremberger, G., Jr.; Schneider, P.; Lieberman, D.; Cheung, T.

    2012-01-01

    Macro-bending fiber optic based heart-rate and pulse pressure shape monitors have been fabricated and tested for non-invasive measurement. Study of fiber bending loss and its stability and variations are very important especially for sensor designs based on optical fiber bending. Wavelengths from 1300 nm to 1550 nm have been used with fabrication based on multimode fiber, single mode fiber, and photonic crystal fiber. The smallest studied curvature would demand the use of single mode standard fibers. The collected data series show high quality suitable for random series analysis. Fractal property of optically measured pulse pressure data has been observed to correlate with physical activity. Correlation to EKG signal suggests that the fabricated monitors are capable of measuring the differential time delays at wrist and leg locations. The difference in time delay could be used to formulate a velocity parameter for diagnostics. The pulse shape information collected by the fiber sensor provides additional parameters for the analysis of the fractal nature of the heart. The application to real time measurement of blood vessel stiffness with this optical non-invasive fiber sensor is discussed.

  6. Pulse shape dependence in the dynamically assisted Sauter-Schwinger effect

    CERN Document Server

    Linder, Malte F; Sicking, Joachim; Szpak, Nikodem; Schützhold, Ralf

    2015-01-01

    While the Sauter-Schwinger effect describes non-perturbative electron-positron pair creation from vacuum by a strong and slowly varying electric field $E_{\\mathrm{strong}}$ via tunnelling, the dynamically assisted Sauter-Schwinger effect corresponds to a strong (exponential) enhancement of the pair creation probability by an additional weak and fast electric or electromagnetic pulse $E_{\\mathrm{weak}}$. Using the WKB and worldline instanton method, we find that this enhancement mechanism strongly depends on the shape of the fast pulse. For the Sauter profile $1/\\cosh^2(\\omega t)$ considered previously, the threshold frequency $\\omega_{\\mathrm{crit}}$ (where the enhancement mechanism sets in) is basically independent of the magnitude $E_{\\mathrm{weak}}$ of the weak pulse -- whereas for a Gaussian pulse $\\exp(-\\omega^2t^2)$, an oscillating profile $\\cos(\\omega t)$ or a standing wave $\\cos(\\omega t)\\cos(kx)$, the value of $\\omega_{\\mathrm{crit}}$ does depend (logarithmically) on $E_{\\mathrm{weak}}/E_{\\mathrm{str...

  7. 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.

  8. Numerical optimization approaches of single-pulse conduction laser welding by beam shape tailoring

    Science.gov (United States)

    Sundqvist, J.; Kaplan, A. F. H.; Shachaf, L.; Brodsky, A.; Kong, C.; Blackburn, J.; Assuncao, E.; Quintino, L.

    2016-04-01

    While circular laser beams are usually applied in laser welding, for certain applications tailoring of the laser beam shape, e.g. by diffractive optical elements, can optimize the process. A case where overlap conduction mode welding should be used to produce a C-shaped joint was studied. For the dimensions studied in this paper, the weld joint deviated significantly from the C-shape of the single-pulse laser beam. Because of the complex heat flow interactions, the process requires optimization. Three approaches for extracting quantitative indicators for understanding the essential heat flow contributions process and for optimizing the C-shape of the weld and of the laser beam were studied and compared. While integral energy properties through a control volume and temperature gradients at key locations only partially describe the heat flow behaviour, the geometrical properties of the melt pool isotherm proved to be the most reliable method for optimization. While pronouncing the C-ends was not sufficient, an additional enlargement of the laser beam produced the desired C-shaped weld joint. The approach is analysed and the potential for generalization is discussed.

  9. 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.

  10. Experimental tests of the new plastic scintillator with pulse shape discrimination capabilities EJ-299-33

    Energy Technology Data Exchange (ETDEWEB)

    Cester, D., E-mail: davide.cester@gmail.com [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Nebbia, G. [INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Stevanato, L. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Pino, F. [Laboratorio de Fisica Nuclear, Universidad Simon Bolivar, Apartado 89000, 1080 A Caracas (Venezuela, Bolivarian Republic of); Viesti, G. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy)

    2014-01-21

    We have studied the prototype of a new plastic scintillator material (EJ-299-33) engineered for gamma-neutron discrimination. Energy and time resolutions as well as pulse shape discrimination capability have been compared with those of standard plastic and liquid scintillators. EJ-299-33 characteristics are somewhat poorer compared to standard scintillators. However, results obtained with the new plastic material suggest its possible use in basic research (time-of-flight measurements) as well as in Homeland Security applications (neutron/gamma monitoring device)

  11. Temperature gain correction for CsI(Tl) detection systems based on digital pulse shape analysis

    International Nuclear Information System (INIS)

    In this paper we propose a pulse shape based method for monitoring the interior temperature of a CsI(Tl) crystal in order to correct the temperature dependence in the energy calibration of the corresponding detector system. The gain dependence on temperature of the CsI(Tl) detector was measured using both, a photomultiplier tube (PMT) and an avalanche photodiode (APD) readout photosensor. The analysis shows that the gain shifts due to temperature variations can be corrected to a precision of better than 1% with both the PMT and the APD, well below the CsI(Tl) intrinsic energy resolution for ~1 MeV γ-rays

  12. 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.

  13. Boundary conditions for arbitrarily shaped and tightly focused laser pulses in electromagnetic codes

    Science.gov (United States)

    Thiele, Illia; Skupin, Stefan; Nuter, Rachel

    2016-09-01

    Investigation of laser matter interaction with electromagnetic codes requires to implement sources for the electromagnetic fields. A way to do so is to prescribe the fields at the numerical box boundaries in order to achieve the desired fields inside the numerical box. Here we show that the often used paraxial approximation can lead to unexpected field profiles with strong impact on the laser matter interaction results. We propose an efficient numerical algorithm to compute the required laser boundary conditions consistent with the Maxwell's equations for arbitrarily shaped, tightly focused laser pulses.

  14. Multiple shock compression of diamond foils with a shaped laser pulse over 1 TPa

    International Nuclear Information System (INIS)

    Experiments on shock compression of diamond foils with intense laser are reported. In order to explore high-pressure and low-temperature region of the carbon phase-diagram, we irradiate single-crystal (Type-Ib) crystal foils with a shaped (ramp) pulse at the pressure of over 1TPa. We observed time-resolved reflectivity from the rear surface of the diamond during the shock compression with velocity interferometer system for any reflector (VISAR). Simultaneous observation of optical measurements and x-ray diffraction has been tested. Preliminary results on decompression of the diamond crystal due to x-ray heating were observed

  15. 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.

  16. D-shaped fiber grating refractive index sensor induced by an ultrashort pulse laser.

    Science.gov (United States)

    Liao, Changrui; Wang, Qiao; Xu, Lei; Liu, Shen; He, Jun; Zhao, Jing; Li, Zhengyong; Wang, Yiping

    2016-03-01

    The fabrication of fiber Bragg gratings was here demonstrated using ultrashort pulse laser point-by-point inscription. This is a very convenient means of creating fiber Bragg gratings with different grating periods and works by changing the translation speed of the fiber. The laser energy was first optimized in order to improve the spectral properties of the fiber gratings. Then, fiber Bragg gratings were formed into D-shaped fibers for use as refractive index sensors. A nonlinear relationship was observed between the Bragg wavelength and liquid refractive index, and a sensitivity of ∼30  nm/RIU was observed at 1.450. This shows that D-shaped fiber Bragg gratings might be used to develop promising biochemical sensors. PMID:26974608

  17. Specific heat capacity and emissivity measurements of ribbon-shaped graphite using pulse current heating

    International Nuclear Information System (INIS)

    A measurement method for specific heat capacity and hemispherical total emissivity of electrically conductive materials with pulse current heating is investigated, in which a ribbon-shaped sample is heated up to 3000 K in a subsecond-duration experiment. Specific heat capacity and hemispherical total emissivity of the sample are calculated from the time variations of heat generation and surface temperature of the sample measured during heating and cooling phases. The true surface temperature of the ribbon-shaped sample is obtained with a radiation thermometer, the directional spectral emissivity of the sample surface is measured using a hemispherical mirror centered at the sample surface. Measurements are performed for POCO AXM-5Q1 graphite in the temperature range from 1500 to 3000 K

  18. 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.

  19. Consistency check of pulse shape discrimination for broad energy germanium detectors using double beta decay data

    International Nuclear Information System (INIS)

    The Gerda (GERmanium Detector Array) experiment was built to study fundamental neutrino properties via neutrinoless double beta decay (0νββ). 0νββ events are single-site events (SSE) confined to a scale about millimeter. However, most of backgrounds are multi-site events (MSE). Broad Energy Germanium detectors (BEGes) offer the potential merits of improved pulse shape recognition efficiencies of SSE/MSE. They allow us to reach the goal of Phase II with a background index of 10-3 cts/(keV.kg.yr) in the ROI. BEGe detectors with a total target mass of 3.63 kg have been installed to the Gerda setup in the Laboratori Nazionali del Gran Sasso (LNGS) in July 2012 and are collecting data since. A consistency check of the pulse shape discrimination (PSD) efficiencies by comparison of calibration data and 2νββ data will be presented. The PSD power of these detectors is demonstrated.

  20. Consistency check of pulse shape discrimination for broad energy germanium detectors using double beta decay data

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Heng-Ye [Max-Planck-Institut fuer Physik, Muenchen (Germany); Collaboration: GERDA-Collaboration

    2013-07-01

    The Gerda (GERmanium Detector Array) experiment was built to study fundamental neutrino properties via neutrinoless double beta decay (0νββ). 0νββ events are single-site events (SSE) confined to a scale about millimeter. However, most of backgrounds are multi-site events (MSE). Broad Energy Germanium detectors (BEGes) offer the potential merits of improved pulse shape recognition efficiencies of SSE/MSE. They allow us to reach the goal of Phase II with a background index of 10{sup -3} cts/(keV.kg.yr) in the ROI. BEGe detectors with a total target mass of 3.63 kg have been installed to the Gerda setup in the Laboratori Nazionali del Gran Sasso (LNGS) in July 2012 and are collecting data since. A consistency check of the pulse shape discrimination (PSD) efficiencies by comparison of calibration data and 2νββ data will be presented. The PSD power of these detectors is demonstrated.

  1. Validation of pulse shape simulation for GERDA Phase II prototype detectors

    International Nuclear Information System (INIS)

    The GERDA (GERmanium Detector Array) Experiment is designed to search for the neutrinoless double beta (0νββ) decay of 76Ge. The 0νββ decay events have two electrons in the final state which deposit their energy predominantly locally, hence are called single-site events. Most of the background events deposit their energy at several different positions inside the detector, hence are called multi-site events. It has been shown that the 18-fold segmented germanium detector designed for GERDA Phase II is quite capable to distinguish between single- and multi- site events. Pulse shape analysis based on signals from the prototype detector has also been carried out recently to further improve the discrimination power. A pulse shape simulation package has been developed to estimate the efficiency of the analysis. The simulation has been compared to different sets of data taken from several GERDA Phase II prototype detectors. It shows that the effects from the crystal structure on the drift of charge carriers can be properly simulated.

  2. 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.

  3. Shape-dependent magnetic properties of Co nanostructure arrays synthesized by pulsed laser melting

    Science.gov (United States)

    Shirato, N.; Sherrill, S.; Gangopadhyay, A. K.; Kalyanaraman, R.

    2016-06-01

    One dimensional (1D) magnetic nanowires show unique magnetic behaviors, such as large coercivity and high remanence, in comparison to the bulk and thin film materials. Here, planar arrays of Co nanowires, nanorods and nanoparticles were fabricated from thin Co films by a nanosecond pulsed laser interference irradiation technique. Magnetic force microscopy (MFM) and surface magneto-optic Kerr effect (SMOKE) techniques were used to study the individual and average magnetic properties of the nanostructures. Magnetic domain orientation was found to depend on the in-plane aspect ratio of the nanostructure. The magnetic orientation was out-of-plane for in-plane aspect ratio ranging from 1 to 1.4 and transitioned to an in-plane orientation for aspect ratios greater than 1.4 (such as in nanorods and nanowires). Our results also showed that polycrystalline Co nanowires showed much higher coercivity and remanence as compared to bulk and thin film materials, as well as shapes with smaller aspect ratio. This result was attributed mainly to the shape anisotropy. This study demonstrated that nanosecond pulsed laser synthesis is capable of fabricating various nanostructures in a simple, robust and rapid manner and SMOKE is a reliable technique to rapidly characterize such magnetic nanostructures.

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

    International Nuclear Information System (INIS)

    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 λSPR=730 nm to λSPR=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.

  5. The Shape of an Auxin Pulse, and What It Tells Us about the Transport Mechanism.

    Directory of Open Access Journals (Sweden)

    Graeme Mitchison

    2015-10-01

    Full Text Available Auxin underlies many processes in plant development and physiology, and this makes it of prime importance to understand its movements through plant tissues. In stems and coleoptiles, classic experiments showed that the peak region of a pulse of radio-labelled auxin moves at a roughly constant velocity down a stem or coleoptile segment. As the pulse moves it becomes broader, at a roughly constant rate. It is shown here that this 'spreading rate' is larger than can be accounted for by a single channel model, but can be explained by coupling of channels with differing polar transport rates. An extreme case is where strongly polar channels are coupled to completely apolar channels, in which case auxin in the apolar part is 'dragged along' by the polar part in a somewhat diffuse distribution. The behaviour of this model is explored, together with others that can account for the experimentally observed spreading rates. It is also shown that saturation of carriers involved in lateral transport can explain the characteristic shape of pulses that result from uptake of large amounts of auxin.

  6. Frequency effects on the electron density and {alpha}-{gamma} mode transition in atmospheric radio frequency discharges

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yuantao [Shandong Provincial Key Lab of UHV Technology and Gas Discharge Physics, School of Electrical Engineering, Shandong University, Jinan, Shandong Province 250061 (China); Cui Shaoyan [School of Mathematics and Information, Ludong University, Yantai, Shandong Province 264025 (China)

    2011-08-15

    In this paper, a one-dimensional model is explored to investigate the frequency effects on the characteristics of atmospheric radio frequency discharges at a given power. The simulation data and analytical results show that the improvement of electron density can be observed with better discharge stability by increasing excitation frequency in an appropriate range. Using the analytical equations deduced from the model, the mean electron density could be inferred by means of the measured parameters. The {alpha}-{gamma} mode transition especially in high frequency discharges is also analytically discussed based on the theoretical equations.

  7. Electromagnetic pulse reflection at self-generated plasma mirrors: laser pulse shaping and high order harmonic generation

    CERN Document Server

    Bulanov, S S; Maksimchuk, A; Matsuoka, T; Nees, J; Pegoraro, F

    2007-01-01

    A thin layer of overdense plasma is created when an electromagnetic pulse interacts with a rapidly ionizing thin foil. This layer will reflect the incoming pulse, forming a so-called plasma mirror. A simple realistic model based on paired kinetic and wave equations is used to describe analytically the process of mirror formation and the reflection and transmission of the incident pulse. The model incorporates the exact description of the ionization process in the foil and the polarization and conduction currents that follow. The analytical description of the reflected and transmitted pulses as well as their dependence on foil parameters, and initial pulse amplitude and form are presented. Possible application and effectiveness of this process to improve laser pulse contrast are discussed. In the case of the linearly polarized incident pulse, there harmonic generation occurs, that is absent in the case of the circular polarization. The spectra of the reflected pulses for different initial forms and amplitudes ...

  8. 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.

  9. 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. PMID:27041091

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

    Energy Technology Data Exchange (ETDEWEB)

    Schlarb, Michael Christian

    2009-11-17

    The capabilities of future HPGe arrays consisting of highly segmented detectors, like AGATA will depend heavily on the performance of {gamma}-ray tracking. The most crucial component in the whole concept is the pulse shape analysis (PSA). The working principle of PSA is to compare the experimental signal shape with signals available from a basis set with known interaction locations. The efficiency of the tracking algorithm hinges on the ability of the PSA to reconstruct the interaction locations accurately, especially for multiple {gamma}-interactions. Given the size of the arrays the PSA algorithm must be run in a real-time environment. A prerequisite to a successful PSA is an accurate knowledge of the detectors response. Making a full coincidence scan of a single AGATA detector, however takes between two and three months, which is too long to produce an experimental signal basis for all detector elements. A straight forward possibility is to use a precise simulation of the detector and to provide a basis of simulated signals. For this purpose the Java Agata Signal Simulation (JASS) was developed in the course of this thesis. The geometry of the detector is given with numerical precision and models describing the anisotropic mobilities of the charge carriers in germanium were taken from the literature. The pulse shapes of the transient and net-charge signals are calculated using weighting potentials on a finite grid. Special care was taken that the interpolation routine not only reproduces the weighting potentials precisely in the highly varying areas of the segment boundaries but also that its performance is independent of the location within the detector. Finally data from a coincidence scan and a pencil beam experiment were used to verify JASS. The experimental signals are reproduced accurately by the simulation. Pulse Shape Analysis (PSA) reconstructs the positions of the individual interactions and the corresponding energy deposits within the detector. This

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

    International Nuclear Information System (INIS)

    The capabilities of future HPGe arrays consisting of highly segmented detectors, like AGATA will depend heavily on the performance of γ-ray tracking. The most crucial component in the whole concept is the pulse shape analysis (PSA). The working principle of PSA is to compare the experimental signal shape with signals available from a basis set with known interaction locations. The efficiency of the tracking algorithm hinges on the ability of the PSA to reconstruct the interaction locations accurately, especially for multiple γ-interactions. Given the size of the arrays the PSA algorithm must be run in a real-time environment. A prerequisite to a successful PSA is an accurate knowledge of the detectors response. Making a full coincidence scan of a single AGATA detector, however takes between two and three months, which is too long to produce an experimental signal basis for all detector elements. A straight forward possibility is to use a precise simulation of the detector and to provide a basis of simulated signals. For this purpose the Java Agata Signal Simulation (JASS) was developed in the course of this thesis. The geometry of the detector is given with numerical precision and models describing the anisotropic mobilities of the charge carriers in germanium were taken from the literature. The pulse shapes of the transient and net-charge signals are calculated using weighting potentials on a finite grid. Special care was taken that the interpolation routine not only reproduces the weighting potentials precisely in the highly varying areas of the segment boundaries but also that its performance is independent of the location within the detector. Finally data from a coincidence scan and a pencil beam experiment were used to verify JASS. The experimental signals are reproduced accurately by the simulation. Pulse Shape Analysis (PSA) reconstructs the positions of the individual interactions and the corresponding energy deposits within the detector. This is

  12. 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...

  13. Study of pulse shape discrimination for beta events on the n+ contact with BEGe detectors

    International Nuclear Information System (INIS)

    For the second phase of the GERDA experiment, bare BEGe detectors will be deployed in liquid argon. In the GERDA commissioning runs it was observed that the 42Ar progeny (42K) can create background at Qββ, if the ions are attracted on the detector surface. Beta particles from 42K decays (Qβ∼3.5 MeV) can penetrate the thick Li layer of the detectors n+ contact surface and generate signals also at Qββ. With BEGe detectors these events can be identified and discriminated via pulse shape analysis. In this talk we present a study of surface beta events discrimination, using measurements of Sr and Ru sources with detectors in vacuum cryostats and the derived expected background suppression factor for 42K in LAr.

  14. 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.

  15. Blind Separation of Two Users Based on User Delays and Optimal Pulse-Shape Design

    Directory of Open Access Journals (Sweden)

    Poor HVincent

    2010-01-01

    Full Text Available A wireless network is considered, in which two spatially distributed users transmit narrow-band signals simultaneously over the same channel using the same power. User separation is achieved by oversampling the received signal and formulating a virtual multiple-input multiple-output (MIMO system based on the resulting polyphase components. Because of oversampling, high correlations can occur between the columns of the virtual MIMO system matrix which can be detrimental to user separation. A novel pulse-shape waveform design is proposed that results in low correlation between the columns of the system matrix, while it exploits all available bandwidth as dictated by a spectral mask. It is also shown that the use of successive interference cancelation in combination with blind source separation further improves the separation performance.

  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. 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.

  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. 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.

  20. Application of pulse-shape discrimination to coplanar CdZnTe detectors

    Science.gov (United States)

    Nakhostin, M.; Podolyak, Zs.; Sellin, P. J.

    2013-11-01

    A digital pulse-shape discrimination algorithm for the identification of multi-site γ-ray interactions in coplanar CdZnTe detectors has been developed. The algorithm is used to suppress the Compton continuum in γ-ray spectroscopy measurements by rejecting the single-site events. The results of our study with a 15×15×7.5 mm3 detector demonstrate the effectiveness of this approach for revealing low intensity γ-ray peaks in the examined energy range (511-1274 keV), which is of importance for environmental and security applications. The method is also very useful for background reduction in the neutrinoless double beta-decay experiments for which coplanar CdZnTe detectors are of interest.

  1. Electromagnetic pulse reflection at self-generated plasma mirrors: laser pulse shaping and high order harmonic generation

    OpenAIRE

    Bulanov, S. S.; Macchi, A.; Maksimchuk, A.; Matsuoka, T.; Nees, J.; Pegoraro, F.

    2007-01-01

    A thin layer of overdense plasma is created when an electromagnetic pulse interacts with a rapidly ionizing thin foil. This layer will reflect the incoming pulse, forming a so-called plasma mirror. A simple realistic model based on paired kinetic and wave equations is used to describe analytically the process of mirror formation and the reflection and transmission of the incident pulse. The model incorporates the exact description of the ionization process in the foil and the polarization and...

  2. Factorization of numbers with the temporal Talbot effect: optical implementation by a sequence of shaped ultrashort pulses.

    Science.gov (United States)

    Bigourd, Damien; Chatel, Béatrice; Schleich, Wolfgang P; Girard, Bertrand

    2008-01-25

    We report on the successful operation of an analogue computer designed to factor numbers. Our device relies solely on the interference of classical light and brings together the field of ultrashort laser pulses with number theory. Indeed, the frequency component of the electric field corresponding to a sequence of appropriately shaped femtosecond pulses is determined by a Gauss sum which allows us to find the factors of a number. PMID:18232947

  3. Factorization of Numbers with the temporal Talbot effect: Optical implementation by a sequence of shaped ultrashort pulses

    OpenAIRE

    Bigourd, Damien; Chatel, Béatrice; Schleich, Wolfgang,; Girard, Bertrand

    2008-01-01

    International audience We report on the successful operation of an analogue computer designed to factor numbers. Our device relies solely on the interference of classical light and brings together the field of ultrashort laser pulses with number theory. Indeed, the frequency component of the electric field corresponding to a sequence of appropriately shaped femtosecond pulses is determined by a Gauss sum which allows us to find the factors of a number.

  4. Shaping of intensive secondary pulsed molecular beam and production of accelerated molecules and radicals in it

    CERN Document Server

    Makarov, G N

    2001-01-01

    The method is described for shaping the intensive secondary pulsed molecular beam, wherein the molecules kinetic energy may be controlled through the powerful IR laser radiation by means of the molecules oscillatory excitation in the source itself. The thickening jump (the shock wave), which is formed by interaction of the intensive pulsed supersonic molecular beam (or flux) with a solid surface, is used as the secondary beam source. The intensive (>= 10 sup 2 sup 0 molecules/stere. s) beams of the SF sub 6 and CF sub 3 I molecules with the kinetic energy correspondingly equal to approximately 1.5 eV and 1.2 eV without gas-carrier and molecular SF sub 6 beams with kinetic energy approx = 2.5 eV are obtained. The spectral and energy characteristics of the SF sub 6 molecules acceleration in the secondary beam are studied. The possibility of obtaining the accelerated radicals in the secondary molecular beam is indicated

  5. 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...

  6. 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 ...

  7. New opportunities for secure communication networks using shaped femtosecond laser pulses inducing filamentation processes in the atmosphere

    International Nuclear Information System (INIS)

    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

  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. Studies of neutron–γ pulse shape discrimination in EJ-309 liquid scintillator using charge integration method

    International Nuclear Information System (INIS)

    Pulse shape discrimination capability based on the charge integration has been investigated for liquid scintillator EJ-309. The effectiveness of neutron–γ discrimination in 4-in. diameter and 3-in. thick EJ-309 cells coupled with 3-in. photomultiplier tubes has been carefully studied in the laboratory environment and compared to the commonly used EJ-301 liquid scintillator formulation. Influences of distortions in pulse shape caused by 13.7-m long cables necessary for some remote operations have been examined. The parameter space for an effective neutron–γ discrimination for these assays, such as position and width of a gate used for integration of the delayed light, has been explored

  10. 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.

  11. Pulse-shape discrimination and energy resolution of a liquid-argon scintillator with xenon doping

    Science.gov (United States)

    Wahl, C. G.; Bernard, E. P.; Lippincott, W. H.; Nikkel, J. A.; Shin, Y.; McKinsey, D. N.

    2014-06-01

    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)% (σ) to (3.5 ± 0.2)% (σ) 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 dopant range, with performance becoming slightly better than pure argon at the highest tested dopant concentration. Some evidence of reduced neutron scintillation efficiency with increasing dopant concentration was observed. Finally, the waveform shape outside the TPB region is discussed, suggesting that the contribution to the waveform from xenon-produced light is primarily in the last portion of the slow component.

  12. 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.

  13. 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.

  14. The impact of photon flight path on S1 pulse shape analysis in liquid xenon two-phase detectors

    International Nuclear Information System (INIS)

    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 increases, the variation in the S1 photon flight path can become comparable to these decay constants, reducing the utility of pulse-shape analysis to separate NR from ER. The effect of path length variations in the LUX detector has been studied using the results of simulations and the impact on the S1 pulse shape analysis is discussed

  15. Pulse Shape Analysis of the Proportional Counter Data from the Third Phase of the Sudbury Neutrino Observatory

    International Nuclear Information System (INIS)

    This poster presented a pulse shape-based analysis of the proportional counter data from the third phase of the Sudbury Neutrino Observatory. It was shown that the neutron signal from the 3He-filled proportional counters could be maintained at about 75% for a suppression of 98% for the alpha background signal.

  16. Pulse shape discrimination performance of stilbene coupled to low-noise silicon photomultipliers

    Energy Technology Data Exchange (ETDEWEB)

    Ruch, Marc Lavi, E-mail: mruch@umich.edu; Flaska, Marek; Pozzi, Sara A

    2015-09-01

    Pulse shape discrimination (PSD) techniques can be used to discern between neutron and gamma-ray interactions in certain organic scintillators. Traditionally, photomultiplier tubes (PMTs) have been used in organic-scintillator assemblies. However, silicon photomultipliers (SiPMs) have great potential to be used in many applications in which PMTs have been predominantly used, including those utilizing PSD techniques. To evaluate the current state of the art of the SiPM technology, SensL's 6-mm B-Series and C-Series SiPMs were compared to a fast Hamamatsu PMT in conjunction with a 6×6×6-mm{sup 3} stilbene organic scintillator to assess the PSD performance of the detector assemblies. Measurements with a Cf-252 source were performed and a figure of merit (FOM) for discriminating between neutron and gamma-ray pulses between 100 keVee and 200 keVee was calculated for each assembly. A digital charge-integration PSD technique was used to process all measured data. The FOM for the B-Series SiPM, PMT, and C-Series SiPM was 1.37, 1.93, and 2.13, respectively. The C-Series SiPM was shown to perform as well as the PMT in the experiments. - Highlights: • Silicon photomultipliers show potential for use in applications that employ PMTs. • SensL C-Series SiPMs have 21% reduction in RMS noise compared to B-Series. • PSD using stilbene coupled to SiPM has improved significantly with low-noise SiPMs. • Such SiPMs can be used to perform PSD as well as PMTs using simple PSD algorithms.

  17. Study on Nd:YAG laser welding of zircaloy-4 using temporal pulse shaping for nuclear applications

    International Nuclear Information System (INIS)

    Zirconium alloys are mainly used in nuclear power plants. It is used for structural parts in the core as pressure tubes, fuel tubes, plug material and garter spring in Pressurized Heavy Water Reactors (PHWR). A study on keyhole mode of laser welding has been performed for the optimization of process parameters for joining of zircaloy-4. Using different temporal pulse shapes of Nd:YAG laser with centre-up shaped pulses, the zircaloy-4 samples were welded successfully with 3.7 mm deep weld depth at 70 J of pulse energy. The analysis and investigation of weld zone in terms of penetration depth, aspect ratio and heat affected zone have also been carried out. (author)

  18. 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.

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

    International Nuclear Information System (INIS)

    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. Theoretical reaction rates of the $^{12}$C($\\alpha$,$\\gamma$)$^{16}$O reaction from the potential model

    CERN Document Server

    Katsuma, M

    2015-01-01

    The radiative capture cross sections of $^{12}$C($\\alpha$,$\\gamma$)$^{16}$O and derived reaction rates are calculated from the direct capture potential model. The resulting $S$-factor at low energies is found to be dominated by $E$2 transition to the $^{16}$O ground state. The $E$1 and $E$2 $S$-factors at $E_{c.m.}=0.3$ MeV are $S_{E1}\\approx3$ keV~b and $S_{E2}=150^{+41}_{-17}$ keV~b, respectively. The sum of the cascade transition through the excited state of $^{16}$O is $S_{\\rm casc}= 18\\pm4.5$ keV~b. The derived reaction rates at low temperatures seem to be concordant with those from the previous evaluation. For astrophysical applications, our reaction rates below $T_9=3$ are provided in an analytic expression.

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

    Directory of Open Access Journals (Sweden)

    R.P. Kelley

    2015-03-01

    Full Text Available 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 radioactive isotopes. This pulse shape expression was fitted to the measured neutron pulse shape using a least-squares optimization algorithm, allowing an empirical analysis of the mechanism of scintillation inside the 4He detector. A further understanding of this mechanism in the 4He detector will advance the use of this system as a neutron spectrometer. For 252Cf neutrons, the triplet and singlet time constants were found to be 970 ns and 686 ns, respectively. For neutrons from the (d,d generator, the time constants were found to be 884 ns and 636 ns. Differences were noted in the magnitude of these parameters compared to previously published data, however the general relationships were noted to be the same and checked with expected trends from theory. Of the excited helium states produced from a 252Cf neutron interaction, 76% were found to be born as triplet states, similar to the result from the neutron generator of 71%. The two sources yielded similar pulse shapes despite having very different neutron energy spectra, validating the robustness of the fits across various neutron energies.

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

    International Nuclear Information System (INIS)

    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 radioactive isotopes. This pulse shape expression was fitted to the measured neutron pulse shape using a least-squares optimization algorithm, allowing an empirical analysis of the mechanism of scintillation inside the 4He detector. A further understanding of this mechanism in the 4He detector will advance the use of this system as a neutron spectrometer. For 252Cf neutrons, the triplet and singlet time constants were found to be 970 ns and 686 ns, respectively. For neutrons from the (d,d) generator, the time constants were found to be 884 ns and 636 ns. Differences were noted in the magnitude of these parameters compared to previously published data, however the general relationships were noted to be the same and checked with expected trends from theory. Of the excited helium states produced from a 252Cf neutron interaction, 76% were found to be born as triplet states, similar to the result from the neutron generator of 71%. The two sources yielded similar pulse shapes despite having very different neutron energy spectra, validating the robustness of the fits across various neutron energies

  3. Pulse shape analysis for the gamma-ray tracking detector Agata

    International Nuclear Information System (INIS)

    Agata is the European project for a 4π gamma-ray tracking array of 180 Ge detectors and is expected to have a detection sensitivity higher by 3 orders of magnitude than that of the present generation of gamma spectrometers. The trajectories of the photons inside a Ge crystal are reconstituted, which allows the determination of the initial energy of the incident photons as the total energy deposited along the track. The sequence of a γ-ray scattering process is too fast compared with the time resolution of the detector to be measured electronically, so tracking algorithms are necessary. Gamma-ray tracking detectors are operating in position sensitive mode it means that Ge crystal are segmented in order to facilitate the localization of the gamma interactions. It is possible to improve the position resolution by using the information conveyed by the shape of the detector signal. The task of the PSA (Pulse Shape Analysis) algorithm is to analyze this signal and extract the number of interactions, the position and the energy of each interaction. PSA algorithms rely on a basis of reference signals given by single interactions and that are obtained through an experimental characterization of the detector with scanning systems. The matrix method is a new PSA algorithm that consists in fitting linearly the detector signal with a set of calculated signals. We have tested this method with both simulated and measured signals. In the case of simulated single interactions the position resolution is 1.4 mm which is within Agata's specifications. For measured signals we have obtained mean positional errors of 3.2 mm at the front end of the detector an 4.8 mm at the back end

  4. 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.

  5. Neutron/gamma pulse shape discrimination in plastic scintillators: Preparation and characterization of various compositions

    International Nuclear Information System (INIS)

    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

  6. 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...

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Arbitrarily-shaped bursts of picosecond pulses from a fiber laser source for high-throughput applications

    Science.gov (United States)

    Desbiens, Louis; Drolet, Mathieu; Roy, Vincent; Sisto, Marco M.; Taillon, Yves

    2011-02-01

    Increasing the ablation efficiency of picosecond laser sources can be performed by bunching pulses in bursts1 and benefit from heat accumulation effects2-5 in the target. Pulsed fiber lasers are well suited for such a regime of operation, as the single pulse energy in a fiber is limited by the onset of nonlinear effects (SPM, SRS). Increasing the number of pulses to form a burst of pulses allows for average power scaling of picosecond fiber lasers. We are presenting in this paper a high-power fiber laser emitting arbitrarily-shaped bursts of picosecond pulses at 20 W of average output power. Burst duration can be varied from 2.5 ns to 80 ns. The burst repetition rate is externally triggered and can be varied from 100 kHz to 1 MHz. The single pulse duration is 60 ps and the repetition rate within a burst is 1.8 GHz. The output beam is linearly polarized (PER > 20 dB) and its M2 value is smaller than 1.15. The laser source has a tunable central wavelength around 1064 nm and a spectral linewidth compatible with frequency conversion. Conversion efficiency higher than 60% has been obtained at 10 W of 1064-nm output power.

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

    OpenAIRE

    Novitsky, Denis

    2012-01-01

    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 anal...

  13. 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.

  14. Pulse shaping using the optical Fourier transform technique - for ultra-high-speed signal processing

    DEFF Research Database (Denmark)

    Palushani, Evarist; Oxenløwe, Leif Katsuo; Galili, Michael;

    2009-01-01

    This paper reports on the generation of a 1.6 ps FWHM flat-top pulse using the optical Fourier transform technique. The pulse is validated in a 320 Gbit/s demultiplexing experiment.......This paper reports on the generation of a 1.6 ps FWHM flat-top pulse using the optical Fourier transform technique. The pulse is validated in a 320 Gbit/s demultiplexing experiment....

  15. 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.

  16. 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

    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...

  17. Optical reprogramming of human somatic cells using ultrashort Bessel-shaped near-infrared femtosecond laser pulses.

    Science.gov (United States)

    Uchugonova, Aisada; Breunig, Hans Georg; Batista, Ana; König, Karsten

    2015-11-01

    We report a virus-free optical approach to human cell reprogramming into induced pluripotent stem cells with low-power nanoporation using ultrashort Bessel-shaped laser pulses. Picojoule near-infrared sub-20 fs laser pulses at a high 85 MHz repetition frequency are employed to generate transient nanopores in the membrane of dermal fibroblasts for the introduction of four transcription factors to induce the reprogramming process. In contrast to conventional approaches which utilize retro- or lentiviruses to deliver genes or transcription factors into the host genome, the laser method is virus-free; hence, the risk of virus-induced cancer generation limiting clinical application is avoided. PMID:26618522

  18. Optical reprogramming of human somatic cells using ultrashort Bessel-shaped near-infrared femtosecond laser pulses

    Science.gov (United States)

    Uchugonova, Aisada; Breunig, Hans Georg; Batista, Ana; König, Karsten

    2015-11-01

    We report a virus-free optical approach to human cell reprogramming into induced pluripotent stem cells with low-power nanoporation using ultrashort Bessel-shaped laser pulses. Picojoule near-infrared sub-20 fs laser pulses at a high 85 MHz repetition frequency are employed to generate transient nanopores in the membrane of dermal fibroblasts for the introduction of four transcription factors to induce the reprogramming process. In contrast to conventional approaches which utilize retro- or lentiviruses to deliver genes or transcription factors into the host genome, the laser method is virus-free; hence, the risk of virus-induced cancer generation limiting clinical application is avoided.

  19. 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.

  20. 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

  1. 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.

  2. Laser beam deflection monitoring of Nd: YAG laser ablation: pulse shape and repetition rate effects

    Science.gov (United States)

    Diaci, Janez; Možina, Janez

    1993-05-01

    The laser beam deflection probe has been employed to study blast waves generated during ablation of metallic surfaces by sequences of 1.06 μm Nd:YAG laser pulses separated by less than 1μs. A fluence threshold has been found, below which the effects of individual pulses can be resolved by the laser probe. Above that, the deflection signal has a similar form as if the surface were irradiated with a single pulse. Analysis of the signals in terms of the spherical blast wave theory shows that a pulse sequence generates a weaker blast wave than a single pulse of equal total energy. On the other hand, the sequence yields a higher etch depth than the single pulse.

  3. Pulse shaping for all-optical signal processing of ultra-high bit rate serial data signals

    DEFF Research Database (Denmark)

    Palushani, Evarist

    ) between dispersed OTDM data and linearly chirped pump pulses. This resulted in spectral compression, enabling the OTDM tributaries to be converted directly onto a dense wavelength division multiplexing (DWDM) grid. The serial-to-parallel conversion was successfully demonstrated for up to 640-GBd OTDM......The following thesis concerns pulse shaping and optical waveform manipulation for all-optical signal processing of ultra-high bit rate serial data signals, including generation of optical pulses in the femtosecond regime, serial-to-parallel conversion and terabaud coherent optical time division...... record-high serial data rates on a single-wavelength channel. The experimental results demonstrate 5.1- and 10.2-Tbit/s OTDM data signals achieved by 16-ary quadrature amplitude modulation (16-QAM), polarization multiplexing and symbol rates as high as 640 GBd and 1.28 TBd. These signal were transmitted...

  4. Spin lock composite and shaped pulses for efficient and robust pumping of dark states in magnetic resonance

    CERN Document Server

    Theis, Thomas; Wu, Tung-Lin; Warren, Warren S

    2013-01-01

    Long-lived (symmetry protected) hyperpolarized spin states offer important new opportunities (for example, in clinical MR imaging), but existing methods for producing these states are limited by either excess energy dissipation or high sensitivity to inhomogeneities. We extend recent work on continuous-wave irradiation of nearly-equivalent spins (spin-lock induced crossing) by designing composite pulse and adiabatic shaped-pulse excitations which overcome the limitations. These composite and adiabatic pulses differ drastically from the traditional solutions in two-level systems. We also show this works in chemically equivalent spin pairs, which has the advantage of allowing for polarization transfer from and to remote spins. The approach is broadly applicable to systems where varying excitation strength induces an avoided crossing to a dark state, and thus to many other spectroscopic regimes.

  5. Pulse shape discrimination between (fast or thermal) neutrons and gamma rays with plastic scintillators: State of the art

    International Nuclear Information System (INIS)

    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

  6. 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.

  7. 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.

  8. 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.

  9. Temporal shaping of nanosecond CO2 laser pulses in multiphoton saturable absorbers

    International Nuclear Information System (INIS)

    It was shown that substantial temporal distortion of nanosecond 10.6 μm laser pulses occurs in traversing multiphoton saturable absorbers. The risetime and pulse delay effects appear to depend both on fluence and wavelength, and to be qualitatively consistent with predictions of a simple two-level absorption model

  10. All-Optical Wavelength Conversion with Amplitude Equalization and Pulse Shaping

    Institute of Scientific and Technical Information of China (English)

    C.W.Chow; C.S.Wong; H.K.Tsang

    2003-01-01

    A dual-wavelength-injection-locked (DWIL) Fabry-Perot (FP) laser is used as an all-optical wavelength converter and regenerator. Regenerated pulses have narrower pulse-width of 37ps. Power penalty and extinction-ratio improvement of 1.5dB and 4dB respectively were achieved.

  11. Absolute hydrogen depth profiling using the resonant $^{1}$H($^{15}$N,$\\alpha\\gamma$)$^{12}$C nuclear reaction

    CERN Document Server

    Reinhardt, Tobias P; Bemmerer, Daniel; Stöckel, Klaus; Wagner, Louis

    2016-01-01

    Resonant nuclear reactions are a powerful tool for the determination of the amount and profile of hydrogen in thin layers of material. Usually, this tool requires the use of a standard of well-known composition. The present work, by contrast, deals with standard-less hydrogen depth profiling. This approach requires precise nuclear data, e.g. on the widely used $^{1}$H($^{15}$N,$\\alpha\\gamma$)$^{12}$C reaction, resonant at 6.4\\,MeV $^{15}$N beam energy. Here, the strongly anisotropic angular distribution of the emitted $\\gamma$-rays from this resonance has been re-measured, resolving a previous discrepancy. Coefficients of (0.38$\\pm$0.04) and (0.80$\\pm$0.04) have been deduced for the second and fourth order Legendre polynomials, respectively. In addition, the resonance strength has been re-evaluated to (25.0$\\pm$1.5)\\,eV, 10\\% higher than previously reported. A simple working formula for the hydrogen concentration is given for cases with known $\\gamma$-ray detection efficiency. Finally, the absolute approach i...

  12. Astrophysical S factor of {$^{12}$C($\\alpha,\\gamma$)$^{16}$O} Calculated with the Reduced R-matrix Theory

    CERN Document Server

    An, Zhen-Dong; Ma, Yu-Gang; Yu, Jian-Kai; Sun, Ye-Ying; Fan, Gong-Tao; Li, Yong-Jiang; Xu, Hang-Hua; Huang, Bo-Song; Wang, Kan

    2015-01-01

    Determination of the accurate astrophysical S factor of {$^{12}$C($\\alpha,\\gamma$)$^{16}$O} reaction has been regarded as a holy grail of nuclear astrophysics for decades. In current stellar models, a knowledge of that value to better than 10\\% is desirable. Due to the practical issues, tremendous experimental and theoretical efforts over nearly 50 years are not able to reach this goal, and the published values contradicted with each other strongly and their uncertainties are 2 times larger than the required precision. To this end we have developed a Reduced R-matrix Theory, based on the classical R-matrix theory of Lane and Thomas, which treats primary transitions to ground state and four bound states as the independent reaction channels in the channel spin representation. With the coordination of covariance statistics and error propagation theory, a global fitting for almost all available experimental data of $^{16}$O system has been multi-iteratively analyzed by our powerful code. A reliable, accurate and ...

  13. MEASUREMENT OF RADIONUCLIDES USING ION CHROMATOGRAPHY AND FLOW-CELL SCINTILLATION COUNTING WITH PULSE SHAPE DISCRIMINATION

    Energy Technology Data Exchange (ETDEWEB)

    R. A. Fjeld; T.A. DeVol; J.D. Leyba

    2000-03-30

    Radiological characterization and monitoring is an important component of environmental management activities throughout the Department of Energy complex. Gamma-ray spectroscopy is the technology most often used for the detection of radionuclides. However, radionuclides which cannot easily be detected by gamma-ray spectroscopy, such as pure beta emitters and transuranics, pose special problems because their quantification generally requires labor intensive radiochemical separations procedures that are time consuming and impractical for field applications. This project focused on a technology for measuring transuranics and pure beta emitters relatively quickly and has the potential of being field deployable. The technology combines ion exchange liquid chromatography and on-line alpha/beta pulse shape discriminating scintillation counting to produce simultaneous alpha and beta chromatograms. The basic instrumentation upon which the project was based was purchased in the early 1990's. In its original commercial form, the instrumentation was capable of separating select activation/fission products in ionic forms from relatively pure aqueous samples. We subsequently developed the capability of separating and detecting actinides (thorium, uranium, neptunium, plutonium, americium, and curium) in less than 30 minutes (Reboul, 1993) and realized that the potential time savings over traditional radiochemical methods for isolating some of these radionuclides was significant. However, at that time, the technique had only been used for radionuclide concentrations that were considerably above environmental levels and for aqueous samples of relatively high chemical purity. For the technique to be useful in environmental applications, development work was needed in lowering detection limits; to be useful in applications involving non-aqueous matrices such as soils and sludges or complex aqueous matrices such as those encountered in waste samples, development work was needed

  14. Is there an Optimal Shape of the Defibrillation Shock: Constant Current vs. Pulsed Biphasic Waveforms

    OpenAIRE

    Ivan Dotsinsky; Tsvetan Mudrov; Vessela Krasteva; Jecho Kostov

    2013-01-01

    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 tha...

  15. Spin and temperature dependence of nuclear deformation using alpha-gamma angular correlations

    International Nuclear Information System (INIS)

    Alpha-particle angular distributions with respect to the spin direction of residual nuclei have been measured in heavy-ion fusion reactions. The spin direction was determined by measuring the γ-ray angular distributions, for each event, using the spin spectrometer. α-particle anisotropies have been extracted for the compound nuclear systems: 110Sn*(94 MeV), 114Sn*(80 MeV), 138Nd*(82 MeV), 164Yb*(67 MeV) and 170Yb*(135 MeV) as a function of the α-particle energy and γ-ray multiplicity. The results are compared with statistical model calculations using transmission coefficients from a spherically symmetric optical model potential. The trend of the anisotropy coefficients below the evaporation Coulomb barrier is consistent with spherical emitting shapes in the case of the Sn* isotopes. Small deformation effects are suggested by the 138Nd* and 164Yb* data. The 170Yb* data indicate a large deformation which increases considerably with increasing spin. These results are in agreement with findings for similar systems in which the decay of the giant resonances built on excited states have been studied. 16 refs., 5 figs

  16. Resonance strengths in the 14N(p,gamma)15O and 15N(p,alpha gamma)12C reactions

    CERN Document Server

    Marta, Michele; Bemmerer, Daniel; Beyer, Roland; Broggini, Carlo; Caciolli, Antonio; Erhard, Martin; Fülöp, Zsolt; Grosse, Eckart; Gyürky, György; Hannaske, Roland; Junghans, Arnd R; Menegazzo, Roberto; Nair, Chithra; Schwengner, Ronald; Szücs, Tamás; Vezzú, Simone; Wagner, Andreas; Yakorev, Dmitry

    2010-01-01

    The 14N(p,gamma)15O reaction is the slowest reaction of the carbon-nitrogen-oxygen cycle of hydrogen burning in stars. As a consequence, it determines the rate of the cycle. The 15N(p,alpha gamma)12C reaction is frequently used in inverse kinematics for hydrogen depth profiling in materials. The 14N(p,gamma)15O and 15N(p,alpha gamma)12C reactions have been studied simultaneously, using titanium nitride targets of natural isotopic composition and a proton beam. The strengths of the resonances at Ep = 1058 keV in 14N(p,gamma)15O and at Ep = 897 and 430 keV in 15N(p,alpha gamma)12C have been determined with improved precision, relative to the well-known resonance at Ep = 278 keV in 14N(p,gamma)15O. The new recommended values are \\omega\\gamma = 0.352$\\pm$0.018, 362$\\pm$20, and 22.0$\\pm$0.9\\,eV for their respective strengths. In addition, the branching ratios for the decay of the Ep = 1058 keV resonance in 14N(p,gamma)15O have been redetermined. The data reported here should facilitate future studies of off-resona...

  17. The key reactions in Stellar helium burning: {sup 12}C({alpha},{gamma}){sup 16}O and {sup 22}Ne({alpha},n){sup 25}Mg

    Energy Technology Data Exchange (ETDEWEB)

    Fey, M. E-mail: fey@ifs.physik.uni-stuttgart.de; Kunz, R.; Hammer, J.W.; Jaeger, M.; Mayer, A.; Krmpotic, E.; Bauer, C.; Meyer, C.; Harissopulos, S.; Paradellis, T.; Staudt, G.; Haas, F.; Papka, P.; Kratz, K.-L.; Pfeiffer, B

    2003-05-05

    The excitation functions of {sup 12}C({alpha},{gamma}){sup 16}O and {sup 22}Ne({alpha},n){sup 25}Mg have been determined with a yet unequaled experimental sensitivity of 10{sup -11} b. From {gamma}-angular distributions the S{sub E1}-and S{sub E2}-factors for {sup 12}C({alpha},{gamma}){sup 16}O have been deduced and extrapolated into the range of helium burning temperatures using the R-matrix method. An improved reaction rate has been calculated: N{sub A}<{sigma}{nu}>=(7.9{+-}2.5)x10{sup -15}cm{sup 3}(mols){sup -1} at T{sub 9} = 0.2. For a more precise extrapolation the excitation function has to be measured with better statistics. Therefore a new experiment on {sup 12}C({alpha},{gamma}){sup 16}O with a better suited setup has been started recently. The accuracy of the {sup 22}Ne({alpha},n){sup 25}Mg reaction rate could be improved considerably compared to previous compilations: N{sub A}<{sigma}{nu}> = (0.88{sub -0.3}{sup +2.6}) x 10{sup -16}cm{sup 3}(mols){sup -1} at T{sub 9} = 0.2.

  18. Numerical study of the electroporation pulse shape effect on molecular uptake of biological cells

    OpenAIRE

    Miklavčič, Damijan; Towhidi, Leila

    2010-01-01

    Background In order to reduce the side-effects of chemotherapy, combined chemotherapy-electroporation (electrochemotherapy) has been suggested. Electroporation, application of appropriate electric pulses to biological cells, can significantly enhance molecular uptake of cells due to formation of transient pores in the cell membrane. It was experimentally demonstrated that the efficiency of electroporation is under the control of electric pulse parameters. However, the theoretical basis for th...

  19. Mast Pulses Shape Trophic Interactions between Fluctuating Rodent Populations in a Primeval Forest

    OpenAIRE

    Nuria Selva; Keith A Hobson; Ainara Cortés-Avizanda; Andrzej Zalewski; José Antonio Donázar

    2012-01-01

    How different functional responses of consumers exploiting pulsed resources affect community dynamics is an ongoing question in ecology. Tree masting is a common resource pulse in terrestrial ecosystems that can drive rodent population cycles. Using stable isotope (δ(13)C, δ(15)N) analyses, we investigated the dietary response of two fluctuating rodent species, the yellow-necked mouse Apodemus flavicollis and the bank vole Myodes glareolus, to mast events in Białowieża Forest (NE Poland). Rod...

  20. 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.

  1. Performance Analysis of Ultra Wideband Multiple Access Time Hopping – Pulse Shape Modulation in Presence of Timing Jitter

    Directory of Open Access Journals (Sweden)

    D. Adhikari

    2014-09-01

    Full Text Available In short-range networks such as wireless personal area networks (WPAN, multiple user wireless connectivity for surveillance would require a wireless technology that supports multiple streams of high-speed data and consumes very little power. Ultra wideband (UWB technology enables wireless connectivity across multiple devices (users addressing the need for high-speed WPAN. Apart from having a distinct advantage of higher data rate over Bluetooth v4.0 (24 Mbps, the UWB technology is also found to be tolerant to frequency-selective multipath fading. In this paper authors discuss a time-hopping pulse shape modulation UWB signalling scheme for ad-hoc high bit rate wireless connectivity for defence applications. Authors analyse multiple access interference for both Gaussian channel and frequency selective multipath fading channel to compare the effects of timing jitter on two types of pulse shapes, namely modified Hermite pulse (MHP and prolate spheroidal wave functions (PSWF. Authors make a comparative analysis of the system performance with respect to PSWF and MHP to ascertain robustness to timing jitter. In the process, authors introduced a new metric of decision factor in timing jitter analysis.Defence Science Journal, Vol. 64, No. 5, September 2014, pp.464-470, DOI:http://dx.doi.org/10.14429/dsj.64.5787

  2. 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...

  3. Digital pulse shape analysis for charged particle identification with a nTD silicon detector and 1 GHz sampling digitizer

    International Nuclear Information System (INIS)

    As a result, the pulse shape depends on the charge, mass and energy of the incident ion. If the particles are injected from the rear side, where the electric field is low, the heavier ions will be stopped nearer to the entrance creating denser plasma there as compared to the lighter ions. As a result both the plasma erosion time and the drift time will be larger for heavier ions as compared to the lighter ions. Thus the rear side injection make the PSA technique more sensitive. However, particle identification using PSA required highly uniform resistivity Si crystal and fast pulse processing. Earlier we have reported PI for 6,7Li using PSA technique with a nTD Si detector and a indigenously developed FPGA based digitizer. In the present experiment we have extended the measurement for heavier ions

  4. 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.

  5. 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.

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

    CERN Document Server

    Liu, Mingzhe; Cheng, Yi; Yang, Jianbo; Wang, Lei; Zan, Guibin

    2015-01-01

    There is a key research issue to accurately select out neutron signals and discriminate gamma signals from a mixed radiation field in the neutron detection. This paper proposes a fractal spectrum discrimination approach by means of different spectrum characteristics of neutron and gamma. Figure of merit and average discriminant error ratio are adopted together to evaluate the discriminant effects. Different neutron and gamma signals with various noises and pulse pile-ups 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 discriminant performance among three methods. The fractal spectrum approach is not sensitive to the high frequency noises and pulse pile-ups. It means that the proposed approach takes the advantages of anti-noises and high discriminant ability, and can be used to better discriminate neutron and gamma in neutron detection.

  7. Laser-pulse-shape control of photofragmentation in the weak-field limit

    DEFF Research Database (Denmark)

    Tiwari, Ashwani Kumar; Dey, Diptesh; Henriksen, Niels Engholm

    2014-01-01

    We demonstrate theoretically that laser-induced coherent quantum interference control of asymptotic states of dissociating molecules is possible even in the (one-photon) weak-field limit starting from a single vibrational eigenstate. Thus, phase dependence in the interaction with a fixed energy...... phase-modulated pulse can persist for some time after the pulse is over. This is illustrated for the nonadiabatic process: I+Br*←IBr→I+Br, where the relative yield of excited Br* can be changed by pure phase modulation. It is shown that the phase is able to influence wave-packet spreading...

  8. 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.

  9. 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.

  10. Light collection and pulse-shape discrimination in elongated scintillator cells for the PROSPECT reactor antineutrino experiment

    Science.gov (United States)

    Ashenfelter, J.; Balantekin, B.; 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.; Martinez Caicedo, D. A.; 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.

    2015-11-01

    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 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.

  11. 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.

  12. 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.

  13. 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.

  14. Shaping SHF train of optical picosecond pulses for generating a photoemission in SHF guns

    International Nuclear Information System (INIS)

    The paper analyses a technique of generating optical picosecond pulses (OPP) through laser beam deflection. The OPP generator consists of a laser, deflection system, optical system and amplifier-converter. The technique of OPP generation through laser beam deflection can be successfully used for triggering photoemission in SHF beams. 8 refs., 2 figs

  15. Africa's Pulse, October 2013 : An Analysis of Issues Shaping Africa's Economic Future

    OpenAIRE

    World Bank

    2013-01-01

    This Africa's pulse newsletter includes the following headings: economic prospects for Sub-Saharan Africa remain strong, but growth is vulnerable to a sharp decline in commodity prices; the region's progress on reducing poverty has been slow, hindered by high inequality; and faster reduction in poverty will require growth with equity.

  16. Evaluation of arterial propagation velocity based on the automated analysis of the Pulse Wave Shape

    International Nuclear Information System (INIS)

    This paper proposes the automatic estimation of the arterial propagation velocity from the pulse wave raw records measured in the region of the radial artery. A fully automatic process is proposed to select and analyze typical pulse cycles from the raw data. An adaptive neuro-fuzzy inference system, together with a heuristic search is used to find a functional approximation of the pulse wave. The estimation of the propagation velocity is carried out via the analysis of the functional approximation obtained with the fuzzy model. The analysis of the pulse wave records with the proposed methodology showed small differences compared with the method used so far, based on a strong interaction with the user. To evaluate the proposed methodology, we estimated the propagation velocity in a population of healthy men from a wide range of ages. It has been found in these studies that propagation velocity increases linearly with age and it presents a considerable dispersion of values in healthy individuals. We conclude that this process could be used to evaluate indirectly the propagation velocity of the aorta, which is related to physiological age in healthy individuals and with the expectation of life in cardiovascular patients.

  17. 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.

  18. 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.

  19. 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.

  20. 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 ...

  1. n/γ Pulse shape discrimination comparison of EJ301 and EJ339A liquid scintillation detectors

    International Nuclear Information System (INIS)

    Highlights: • We model the optical process in liquid scintillator with Geant4 simulation toolkit. • We combine the optical process and the PMT response to simulate anode signal. • We performed experiments to benchmark the simulation results. • EJ301 and EJ339A are both good for PSD from simulation and experiment results. • EJ301 has a better PSD feature than EJ339A. - Abstract: In this work, we evaluated the neutron-gamma discrimination capability of EJ301 and EJ339A liquid scintillation detectors via the pulse shape discrimination (PSD) method. Both simulation and experimental results are reported. The Geant4 simulation toolkit was used to model the scintillation process inside the scintillator, for neutron and gamma events, respectively. For the experiments, a high-speed digitizer was used to acquire data, which was then processed in MATLAB. This work compared the PSD performance of two liquid scintillation detectors and demonstrated the capability of Geant4 with regard to simulation of pulse shape

  2. 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.)

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Laser micro-processing of silicon using nanosecond pulse shaped fibre laser at 1 ?m wavelength

    OpenAIRE

    LI, Kun

    2012-01-01

    Processing of Si in the semiconductor and solar cell industry has been dominated by the Diode Pumped Solid State (DPSS) Ultraviolet (UV) laser. Recent advances in laser source technology have produced fibre lasers with Master Oscillator Power Amplifier (MOPA) architectures that offer high repetition rates, high operational efficiencies, and pulse modulation controls exceeding those of typical Q-switched DPSS lasers. The aim of this research is to investigate 1 ?m fibre laser machining of Si w...

  8. Mast pulses shape trophic interactions between fluctuating rodent populations in a primeval forest.

    Science.gov (United States)

    Selva, Nuria; Hobson, Keith A; Cortés-Avizanda, Ainara; Zalewski, Andrzej; Donázar, José Antonio

    2012-01-01

    How different functional responses of consumers exploiting pulsed resources affect community dynamics is an ongoing question in ecology. Tree masting is a common resource pulse in terrestrial ecosystems that can drive rodent population cycles. Using stable isotope (δ(13)C, δ(15)N) analyses, we investigated the dietary response of two fluctuating rodent species, the yellow-necked mouse Apodemus flavicollis and the bank vole Myodes glareolus, to mast events in Białowieża Forest (NE Poland). Rodent hair samples were obtained non-invasively from faeces of their predators for an 11-year period that encompassed two mast events. Spectacular seed crops of deciduous trees, namely oak Quercus robur and hornbeam Carpinus betulus, occur after several intermediate years of moderate seed production, with a post-mast year characterised by a nil crop. While a Bayesian isotopic (SIAR) mixing model showed a variety of potential vegetation inputs to rodent diets, the isotopic niche of the yellow-necked mouse was strongly associated with mast of deciduous trees (>80% of diet), showing no variation among years of different seed crop. However, bank voles showed a strong functional response; in mast years the vole shifted its diet from herbs in deciduous forest (~66% of diet) to mast (~74%). Only in mast years did the isotopic niche of both rodent species overlap. Previous research showed that bank voles, subordinate and more generalist than mice, showed higher fluctuations in numbers in response to masting. This study provides unique data on the functional response of key pulse consumers in forest food webs, and contributes to our understanding of rodent population fluctuations and the mechanisms governing pulse-consumer interactions. PMID:23251475

  9. Mast pulses shape trophic interactions between fluctuating rodent populations in a primeval forest.

    Directory of Open Access Journals (Sweden)

    Nuria Selva

    Full Text Available How different functional responses of consumers exploiting pulsed resources affect community dynamics is an ongoing question in ecology. Tree masting is a common resource pulse in terrestrial ecosystems that can drive rodent population cycles. Using stable isotope (δ(13C, δ(15N analyses, we investigated the dietary response of two fluctuating rodent species, the yellow-necked mouse Apodemus flavicollis and the bank vole Myodes glareolus, to mast events in Białowieża Forest (NE Poland. Rodent hair samples were obtained non-invasively from faeces of their predators for an 11-year period that encompassed two mast events. Spectacular seed crops of deciduous trees, namely oak Quercus robur and hornbeam Carpinus betulus, occur after several intermediate years of moderate seed production, with a post-mast year characterised by a nil crop. While a Bayesian isotopic (SIAR mixing model showed a variety of potential vegetation inputs to rodent diets, the isotopic niche of the yellow-necked mouse was strongly associated with mast of deciduous trees (>80% of diet, showing no variation among years of different seed crop. However, bank voles showed a strong functional response; in mast years the vole shifted its diet from herbs in deciduous forest (~66% of diet to mast (~74%. Only in mast years did the isotopic niche of both rodent species overlap. Previous research showed that bank voles, subordinate and more generalist than mice, showed higher fluctuations in numbers in response to masting. This study provides unique data on the functional response of key pulse consumers in forest food webs, and contributes to our understanding of rodent population fluctuations and the mechanisms governing pulse-consumer interactions.

  10. Two-way shape memory effect and mechanical properties of Pulse Discharge Sintered Ni2.18Mn0.82Ga

    OpenAIRE

    Takagi, T; Khovailo, V.; Nagatomo, T.; Matsumoto, M.; Ohtsuka, M; T. Abe; Miki, H

    2003-01-01

    Mechanical and shape memory properties of a polycrystalline Ni2.18Mn0.82Ga alloy prepared by a PDS (Pulse Discharge Sintering) method were investigated. It was found that the material demonstrates the two-way shape memory effect after a loading - unloading cycle performed in the martensitic state, i. e. essentially without special training. The samples exhibiting the two-way shape memory effect show a significant enhancement in the magnitude of magnetic-field-induced strain.

  11. Shifting the boundaries: pulse-shape effects in the atom-optics kicked rotor

    OpenAIRE

    Jones, P H; Goonasekera, M.; Saunders-Singer, H. E.; Meacher, D. R.

    2004-01-01

    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...

  12. 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.

  13. 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.

  14. Breakout from the hot CNO cycle: the {sup 15}O({alpha},{gamma}) and {sup 18}Ne({alpha},p) reactions

    Energy Technology Data Exchange (ETDEWEB)

    Bradfield-Smith, W.; Laird, A.M.; Davinson, T.; Pietro, A. di; Ostrowski, A.N.; Shotter, A.C.; Woods, P.J. [Dept. of Physics and Astronomy, Univ. of Edinburgh (United Kingdom); Cherubini, S.; Galster, W.; Graulich, J.S.; Leleux, P.; Michel, L.; Ninane, A.; Vervier, J. [Inst. de Physique Nucleaire, UCL, Louvain-la-Neuve (Belgium); Aliotta, M.; Cali, D.; Cappussello, F.; Cunsolo, A.; Spitaleri, C. [INFN, Catania (Italy); Gorres, J.; Wiescher, M. [Notre Dame Univ. (United States); Rahighi, J. [Van de Graaf Lab., Tehran (Iran, Islamic Republic of); Hinnefeld, J. [Indiana Univ., South Bend (United States)

    1998-06-01

    One of the most important reactions which determines the rate of breakout from the hot CNO cycle is the {sup 15}O({alpha},{gamma}){sup 19}Ne. The reaction {sup 18}Ne({alpha},p){sup 21}Na may also provide an alternative breakout route. Experiments are being undertaken at Louvain-La-Neuve using the radioactive {sup 18}Ne beam to study these reactions by measurement of {alpha}({sup 18}Ne,p){sup 21}Na and d({sup 18}Ne,p){sup 19}Ne{sup *} {yields} {sup 15}O + {alpha} (orig.)

  15. Satellite and opacity effects on resonance line shapes produced from short-pulse laser heated foils

    Energy Technology Data Exchange (ETDEWEB)

    Shepherd, Ronnie E-mail: shepherd1@llnl.gov; Audebert, P.; Chen, H-K.; Fournier, K.B.; Peyreusse, O.; Moon, S.; Lee, R.W.; Price, D.; Klein, L.; Gauthier, J.C.; Springer, P

    2003-11-01

    We measure the He-like, time-resolved emission from two types of thin foils (1) consisting of 250 Angst of carbon together with 250 Angst of aluminum and (2) 500 Angst aluminum, illuminated with a 150 fs laser pulse at an intensity of 10{sup 19} W/cm{sup 2}. Dielectronic satellite contributions to the resonance transitions 1s{sup 2}-1s2p({sup 1}P), 1s{sup 2}-1s3p({sup 1}P), and 1s{sup 2}-1s4p({sup 1}P) are modeled using the configuration-averaged code AVERROES and is found to be significant for all three resonance lines. The effects of opacity are inferred from the data and found to be significant only in the 1s{sup 2}-1s2p({sup 1}P)

  16. 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).

  17. A Method for Ultrashort Electron Pulse Shape-Measurement Using Coherent Synchrotron Radiation

    CERN Document Server

    Geloni, G A; Schneidmiller, E A; Yurkov, M V

    2003-01-01

    In this paper we discuss a method for nondestructive measurements of the longitudinal profile of sub-picosecond electron bunches for X-Ray Free Electron Lasers (XFELs). The method is based on the detection of the Coherent Synchrotron Radiation (CSR) spectrum produced by a bunch passing a dipole magnet system. This work also contains a systematic treatment of synchrotron radiation theory which lies at the basis of CSR. Standard theory of synchrotron radiation uses several approximations whose applicability limits are often forgotten: here we present a systematic discussion about these assumptions. Properties of coherent synchrotron radiation from an electron moving along an arc of a circle are then derived and discussed. We describe also an effective and practical diagnostic technique based on the utilization of an electromagnetic undulator to record the energy of the coherent radiation pulse into the central cone. This measurement must be repeated many times with different undulator resonant frequencies in or...

  18. Application of the A/E pulse shape discrimination method to first Ge-76 enriched BEGe detectors operated in GERDA

    Energy Technology Data Exchange (ETDEWEB)

    Lazzaro, Andrea; Agostini, Matteo; Budjas, Dusan; Schoenert, Stefan [Physik-Department E15, Technische Universitaet Muenchen (Germany); Collaboration: GERDA-Collaboration

    2013-07-01

    In 2013 the Gerda experiment will be upgraded to its second phase with more than double of the current {sup 76}Ge mass. The additional diodes are custom made Broad Energy Germanium (BEGe) detectors. This design has been chosen to enhance the pulse shape discrimination (PSD) capability, with respect to the Phase I coaxial detectors. The goal of Phase II is to improve by one order of magnitude the current background index; the PSD will bring a major contribution to this result. Since summer 2012 the first set of five enriched BEGe detectors are operated in Gerda Phase I. This offers us the possibility to test the PSD performances and the signal analysis in an environment as close as possible to the Gerda Phase II configuration. In this talk I present the A/E analysis, the calibration of the cut parameters and the results in terms of background reduction for the data taken with these enriched BEGe.

  19. Application of the A/E pulse shape discrimination method to first Ge-76 enriched BEGe detectors operated in GERDA

    International Nuclear Information System (INIS)

    In 2013 the Gerda experiment will be upgraded to its second phase with more than double of the current 76Ge mass. The additional diodes are custom made Broad Energy Germanium (BEGe) detectors. This design has been chosen to enhance the pulse shape discrimination (PSD) capability, with respect to the Phase I coaxial detectors. The goal of Phase II is to improve by one order of magnitude the current background index; the PSD will bring a major contribution to this result. Since summer 2012 the first set of five enriched BEGe detectors are operated in Gerda Phase I. This offers us the possibility to test the PSD performances and the signal analysis in an environment as close as possible to the Gerda Phase II configuration. In this talk I present the A/E analysis, the calibration of the cut parameters and the results in terms of background reduction for the data taken with these enriched BEGe.

  20. Single and two-photon fluorescence control of Er{sup 3+} ions by phase-shaped femtosecond laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shian, E-mail: sazhang@phy.ecnu.edu.cn; Ding, Jingxin; Lu, Chenhui; Jia, Tianqing; Sun, Zhenrong, E-mail: zrsun@phy.ecnu.edu.cn [State Key Laboratory of Precision Spectroscopy, and Department of Physics, East China Normal University, Shanghai 200062 (China); Xu, Shuwu [State Key Laboratory of Precision Spectroscopy, and Department of Physics, East China Normal University, Shanghai 200062 (China); School of Science, Nantong University, Nantong 226007 (China); Qiu, Jianrong [State Key Laboratory of Luminescent Materials and Devices, and Institute of Optical Communication Materials, South China University of Technology, Wushan Road 381, Guangzhou 510640 (China)

    2014-01-06

    We experimentally demonstrate the control of the single and two-photon fluorescence (SPF and TPF) in Er{sup 3+} ions by shaping the femtosecond laser pulse with a π or square phase modulation. With the low laser intensity (8.4 × 10{sup 10} W/cm{sup 2}), SPF keeps a constant while TPF is effectively suppressed by the two control schemes. With the high laser intensity (1.2 × 10{sup 13} W/cm{sup 2}), both SPF and TPF are simultaneously enhanced or suppressed by the π phase modulation, and SPF is enhanced while TPF is effectively suppressed by the square phase modulation. The up/down-conversion fluorescence enhancement, suppression, or tuning by the optical control method can greatly expand its applications in various related fields.

  1. Pulse shape discrimination capability of metal-loaded organic liquid scintillators for a short-baseline reactor neutrino experiment

    Science.gov (United States)

    Kim, B. R.; Han, B. Y.; Jeon, E. J.; Joo, K. K.; Kang, Jeongsoo; Khan, N.; Kim, H. J.; Kim, Hyunsoo; Kim, J. Y.; Siyeon, Kim; Kim, S. C.; Kim, Yeongduk; Ko, Y. J.; Lee, Jaison; Lee, Jeong-Yeon; Lee, J. Y.; Ma, K. J.; Park, Hyeonseo; Park, H. K.; Park, K. S.; Seo, K. M.; Seon, Gwang-Min; Yeo, I. S.; Yeo, K. M.

    2015-05-01

    A new short-baseline (SBL) reactor neutrino experiment is proposed to investigate a reactor anti-neutrino anomaly. A liquid scintillator (LS) is used to detect anti-neutrinos emitted from a Hanaro reactor, and the pulse shape discrimination (PSD) ability of the metal-loaded organic LSs is evaluated on small-scale laboratory samples. PSD can be affected by selecting different base solvents, and several of the LSs used two different organic base solvents, such as linear alkyl benzene and di-isopropylnaphthalene. For the metallic content, gadolinium (Gd) or lithium (6Li) was loaded into a home-made organic LS and into a commercially available liquid scintillation cocktail. A feasibility study was performed for the PSD using several different liquid scintillation cocktails. In this work, the preparation and the PSD characteristics of a promising candidate, which will be used in an above-ground environment, are summarized and presented.

  2. Enhanced collimated GeV monoenergetic ion acceleration from a shaped foil target irradiated by a circularly polarized laser pulse

    CERN Document Server

    Chen, M; Yu, T P; Sheng, Z M

    2009-01-01

    Using multi-dimensional particle-in-cell (PIC) simulations we study ion acceleration from a foil irradiated by a circularly polarized laser pulse at 1022W/cm^2 intensity. When the foil is shaped initially in the transverse direction to match the laser intensity profile, the center part of the target can be uniformly accelerated for a longer time compared to a usual flat target. Target deformation and undesirable plasma heating are effectively suppressed. The final energy spectrum of the accelerated ion beam is improved dramatically. Collimated GeV quasi-mono-energetic ion beams carrying as much as 18% of the laser energy are observed in multi-dimensional simulations. Radiation damping effects are also checked in the simulations.

  3. 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.

  4. 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.

  5. 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.

  6. A novel non-iterative shape method for estimating the decay time constant of the finger photoplethysmographic pulse

    Institute of Scientific and Technical Information of China (English)

    Ling-xiao HOU; Ming WEI; Xuan WANG; Xin-zhong CHEN; Ying FENG; Kai JIANG

    2011-01-01

    The photoplethysmogram (PPG) of a pulse wave, similar in appearance to the arterial blood pressure (ABP) waveform, contains rich information about the cardiovascular system. The decay time constant RC, equal to the product of peripheral resistance R and total arterial compliance C, is a meaningful cardiovascular model parameter in vascular assessment. Using or ameliorating the existing ABP methods does not achieve a satisfactory estimation of RC from the PPG volume pulse (VRC). Thus,a novel non-iterative shape method (NSM) of evaluating VRC is introduced in this paper. The mathematic expression between a novel, readily available morphological parameter called the area difference ratio (ADR) and VRC was established. As it was difficult to calculate VRC from the complicated expression analytically, we recommend estimating it using a piecewise linear interpolation criterion. Also, since the effect of the PPG magnitude is eliminated in the calculation of ADR, precaliberation or normalization is dispensable in the NSM. Results of human experiments indicated that the NSM was computationally efficient,and the simulation experiments confirmed that the NSM was theoretically available for ABP.

  7. Experimental measurements of the O15(alpha,gamma)Ne19 reaction rate vs. observations of type I X-ray bursts

    CERN Document Server

    Fisker, J L; Görres, J; Wiescher, M; Cooper, R L; Fisker, Jacob Lund; Tan, Wanpeng; Goerres, Joachim; Wiescher, Michael; Cooper, Randall L.

    2007-01-01

    Neutron stars in close binary star systems often accrete matter from their companion stars. Thermonuclear ignition of the accreted material in the atmosphere of the neutron star leads to a thermonuclear explosion which is observed as an X-ray burst occurring periodically between hours and days depending on the accretion rate. The ignition conditions are characterized by a sensitive interplay between the continuously accreting fuel supply and depletion by nuclear burning via the hot CNO cycles. Therefore the ignition depends critically on the hot CNO breakout reaction O15(alpha,gamma)Ne19 that regulates the flow between the beta-limited hot CNO cycle and the rapid proton capture process. Until recently, the O15(alpha,gamma)Ne19 reaction rate was not known experimentally and the theoretical estimates carried significant uncertainties. In this paper we report on the astrophysical consequences of the first measurement of this reaction rate on the thermonuclear instability that leads to type I X-ray bursts on accr...

  8. Pulsed current wave shaping with a transmission line by utilizing superposition of a forward and a backward voltage wave for fast capillary Z-pinch discharge

    International Nuclear Information System (INIS)

    By using a water transmission line, current wave shaping was demonstrated for a fast capillary Z-pinch discharge recombination soft x-ray laser study. The pulsed power system consists of a water capacitor, a gap switch, a transmission line, and a capillary plasma load. A voltage wave initiated at the water capacitor propagates toward the capillary load through the transmission line. Control of the pulse delay that occurred in the transmission line provides the superposition of the forward and the backward voltage waves effectively in order to perform current wave shaping with higher current amplitude and rapid current decay.

  9. 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...

  10. A Parametric Shaping Pulse for PAPR Reduction in OFDM System%一种降低OFDM系统PAPR的参数化整形脉冲

    Institute of Scientific and Technical Information of China (English)

    杨宏周; 杨灿美

    2014-01-01

    在应用脉冲整形( PS )技术降低 OFDM 系统 PAPR 的基础上,提出一种新颖的参数化的Nyquist脉冲称之为参数化正切脉冲,此脉冲包含的设计参数k可以根据系统滚降系数β自由调整,从而尽量降低系统的PAPR。仿真结果表明,相比于常见的升余弦脉冲和反转指数脉冲,新提出的脉冲在降低PAPR性能和保证BER性能方面优势明显,是一种灵活低复杂度的降低OFDM系统PA-PR的脉冲整形方案。%A new and parametric Nyquist pulse named as parametric tangent pulse is proposed for peak-to-average power ratio ( PAPR ) reduction in orthogonal frequency division multiplexing ( OFDM ) systems using pulse shaping . The proposed pulse contains a new design parameter, k, giving an additional degree of freedom to minimize PAPR for a given roll-off factor, β . Simulation results indicate that the proposed pulse can achieve better performance in terms of PAPR reduction and bit error rate ( BER) , as compared with the traditional raised cosine pulse and flipped-exponential pulse. It is an effective scheme with low complexity and high flexibility to reduce the PAPR of OFDM system by pulse shaping with the proposed parametric tangent Nyquist pulse.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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...

  16. Construction and testing of a neutron and gamma spectrometry system using pulse shape discrimination with an organic scintillator

    Science.gov (United States)

    Pope, Robert S.

    1993-03-01

    The goal of this thesis was to construct and test a neutron detector to measure the energy spectrum of 1 to 14-MeV neutrons in the presence of gammas. A spectrometer based on the process of pulse shape discrimination (PSD) was constructed, in which the scintillator NE-213 was used. The primary neutron/gamma sources used were 78-mCi and 4.7-Ci Pu-239Be sources, while 4.7-micro-Ci and 97.6-micro-Ci Na-22 gamma sources were used for energy calibration and additional testing of the detector. Proton recoil spectra and Compton electron spectra were unfolded with the neutron and gamma unfolding code FORIST to generate the incident neutron and gamma spectra, respectively. FORIST, which was written for a CDC computer, was modified to run on a VAX 6420. The experimental spectra were compared to those in the literature. The locations of the peaks in the Pu-239Be spectrum agreed with the literature to within 8.3%, the Pu-239Be gamma spectrum agreed to within 0.7%, while the Na-22 gamma spectrum agreed exactly. Uncertainties in the detection system and unfolding procedure are on the order of 5-10%. This thesis is intended to be a summary of the relevant literature and a user's guide to the PSD spectrometer.

  17. 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.

  18. Inducing a sign inversion in one state of a two-state superposition using ultrafast pulse shaping

    International Nuclear Information System (INIS)

    An ultrafast pulse shaping scheme is presented that transiently modifies a two-state superposition on the E 1Σg+ curve of the lithium dimer. At short time delays, the wave-function amplitude of one of the states is forced to undergo a sign change, while the sign of the second state is programmed to remain static, analogous to the operation of a quantum-computational Z gate. This is observed as a π phase shift in the time-dependent wave-packet signal for pump-probe delays <1.5 ps, relative to longer time delays, greater than 2.5 ps. This shift in sign is accomplished by taking advantage of the separability of the resonant and nonresonant light field effects in the creation of the excited-state wave function. The results show that, for a single state, the resonant and nonresonant light field effects can either be added or subtracted to create the total time evolution of the excited-state wave-function coefficient. If the nonresonant contributions are subtracted from the resonant ones at a time delay when the nonresonant term dominates, then for a short time the excited-state coefficient will have a sign opposite to that at long time, where the resonant term dominates. A desired phase function is derived to produce the opposition in sign of resonant versus nonresonant contributions, and the experimental transient Z-gate matrix elements are quantified

  19. 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)

  20. 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-

  1. Excitation of muonic molecules ddμ and dtμ by super-intense attosecond soft X-ray laser pulses: shaped post-laser-pulse muonic oscillations and enhancement of nuclear fusion

    International Nuclear Information System (INIS)

    The quantum dynamics of muonic molecular ions ddμ and dtμ excited by linearly polarized along the molecular (z)-axis super-intense laser pulses is studied beyond the Born–Oppenheimer approximation by the numerical solution of the time-dependent Schroedinger equation within a three-dimensional model, including the internuclear distance R and muon coordinates z and ρ. The peak-intensity of the super-intense laser pulses used in our simulations is I0 = 3.51 × 1022 W/cm2 and the wavelength is λl = 5 nm. In both ddμ and dtμ, expectation values〈z〉 and 〈ρ〉 of muon demonstrate “post-laser-pulse” oscillations after the ends of the laser pulses. In ddμ post-laser-pulse z-oscillations appear as shaped nonoverlapping “echo-pulses”. In dtμ post-laser-pulse muonic z-oscillations appear as comparatively slow large-amplitude oscillations modulated with small-amplitude pulsations. The post-laser-pulse ρ-oscillations in both ddμ and dtμ appear, for the most part, as overlapping “echo-pulses”. The post-laser-pulse oscillations do not occur if the Born–Oppenheimer approximation is employed. Power spectra generated due to muonic motion along both optically active z and optically passive ρ degrees of freedom are calculated. The fusion probability in dtμ can be increased by more than 11 times by making use of three sequential super-intense laser pulses. The energy released from the dt fusion in dtμ can by more than 20 GeV exceed the energy required to produce a usable muon and the energy of the laser pulses used to enhance the fusion. The possibility of power production from the laser-enhanced muon-catalyzed fusion is discussed. (author)

  2. 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.

  3. A new method for measuring the pulse-front distortion of arbitrary shapes in high-power ultrashort laser systems

    Institute of Scientific and Technical Information of China (English)

    Zuo Yan-Lei; Jiang Dong-Bin; Zhu Qi-Hua; Dong Jun; Zen Xiao-Ming; Huang Xiao-Jun; Huang Zheng

    2012-01-01

    We present a new method that can be used to calculate pulse-front distortion by measuring the spectral interference of two point-diffraction fields in their overlapped district.We demonstrate,for the first time,the measurement of the pulse-front distortion of the pulse from a complex multi-pass amplification system,which exists in almost all high-power laser systems,and obtain the irregular pulse-front distribution.The method presented does not need any reference light or assumption about the pulse-front distribution,and has an accuracy of several femtoseconds.

  4. 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).

  5. 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).

  6. 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.

  7. 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.

  8. 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...

  9. Reaction rate sensitivity of 44Ti production in massive stars and implications of a thick target yield measurement of 40Ca(alpha,gamma)44Ti

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, R D; Sheets, S A; Burke, J T; Scielzo, N D; Rauscher, T; Norman, E B; Tumey, S; Brown, T A; Grant, P G; Hurst, A M; Phair, L; Stoyer, M A; Wooddy, T; Fisker, J L; Bleuel, D

    2010-02-16

    We evaluate two dominant nuclear reaction rates and their uncertainties that affect {sup 44}Ti production in explosive nucleosynthesis. Experimentally we develop thick-target yields for the {sup 40}Ca({alpha},{gamma}){sup 44}Ti reaction at E{sub {alpha}} = 4.13, 4.54, and 5.36 MeV using {gamma}-ray spectroscopy. At the highest beam energy, we also performed an activation measurement which agrees with the thick target result. From the measured yields a stellar reaction rate was developed that is smaller than current statistical-model calculations and recent experimental results, which would suggest lower {sup 44}Ti production in scenarios for the {alpha}-rich freeze out. Special attention has been paid to assessing realistic uncertainties of stellar reaction rates produced from a combination of experimental and theoretical cross sections. With such methods, we also develop a re-evaluation of the {sup 44}Ti({alpha},p){sup 47}V reaction rate. Using these two rates we carry out a sensitivity survey of {sup 44}Ti synthesis in eight expansions representing peak temperature and density conditions drawn from a suite of recent supernova explosion models. Our results suggest that the current uncertainty in these two reaction rates could lead to as large an uncertainty in {sup 44}Ti synthesis as that produced by different treatments of stellar physics.

  10. Spectroscopy of $^{19}$Ne for the thermonuclear $^{15}$O($\\alpha,\\gamma$)$^{19}$Ne and $^{18}$F($p,\\alpha$)$^{15}$O reaction rates

    CERN Document Server

    Parikh, A; de Séréville, N; Wimmer, K; Faestermann, T; Hertenberger, R; Seiler, D; Wirth, H -F; Adsley, P; Fulton, B R; Hammache, F; Kiener, J; Stefan, I

    2015-01-01

    Uncertainties in the thermonuclear rates of the $^{15}$O($\\alpha,\\gamma$)$^{19}$Ne and $^{18}$F($p,\\alpha$)$^{15}$O reactions affect model predictions of light curves from type I X-ray bursts and the amount of the observable radioisotope $^{18}$F produced in classical novae, respectively. To address these uncertainties, we have studied the nuclear structure of $^{19}$Ne over $E_{x} = 4.0 - 5.1$ MeV and $6.1 - 7.3$ MeV using the $^{19}$F($^{3}$He,t)$^{19}$Ne reaction. We find the $J^{\\pi}$ values of the 4.14 and 4.20 MeV levels to be consistent with $9/2^{-}$ and $7/2^{-}$ respectively, in contrast to previous assumptions. We confirm the recently observed triplet of states around 6.4 MeV, and find evidence that the state at 6.29 MeV, just below the proton threshold, is either broad or a doublet. Our data also suggest that predicted but yet unobserved levels may exist near the 6.86 MeV state. Higher resolution experiments are urgently needed to further clarify the structure of $^{19}$Ne around the proton thresh...

  11. Total and partial cross sections of the $^{112}$Sn($\\alpha,\\gamma$)$^{116}$Te reaction measured via in-beam $\\gamma$-ray spectroscopy

    CERN Document Server

    Netterdon, L; Scholz, P; Zilges, A

    2015-01-01

    An extended database of experimental data is needed to address uncertainties of the nuclear-physics input parameters for Hauser-Feshbach calculations. Especially $\\alpha$+nucleus optical model potentials at low energies are not well known. The in-beam technique with an array of high-purity germanium (HPGe) detectors was successfully applied to the measurement of absolute cross sections of an ($\\alpha$,$\\gamma$) reaction on a heavy nucleus at sub-Coulomb energies. The total and partial cross-section values were measured by means of in-beam $\\gamma$-ray spectroscopy. Total and partial cross sections were measured at four different $\\alpha$-particle energies from $E_\\alpha = 10.5$ MeV to $E_\\alpha = 12$ MeV. The measured total cross-section values are in excellent agreement with previous results obtained with the activation technique, which proves the validity of the applied method. The experimental data was compared to Hauser-Feshbach calculations using the nuclear reaction code TALYS. A modified version of the...

  12. A Heuristic Fast Method to Solve the Nonlinear Schroedinger Equation in Fiber Bragg Gratings with Arbitrary Shape Input Pulse

    International Nuclear Information System (INIS)

    Using a combination of Runge-Kutta and Jacobi iterative method, we could solve the nonlinear Schroedinger equation describing the pulse propagation in FBGs. By decomposing the electric field to forward and backward components in fiber Bragg grating and utilizing the Fourier series analysis technique, the boundary value problem of a set of coupled equations governing the pulse propagation in FBG changes to an initial condition coupled equations which can be solved by simple Runge-Kutta method.

  13. 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...

  14. Coherent control and quantum shaping with the laser pulse%激光脉冲的量子整形与相干控制

    Institute of Scientific and Technical Information of China (English)

    阿布力米提·吾买尔; 任立庆; 张敏华; 许康; 李永放

    2011-01-01

    The interaction between the laser pulse with a small-area and a three-level atomic system is investigated. The formation and characterization of the shaped laser pulse are analyzed and the two-photon transition is studied with the shaped laser pulse. The influence of the relaxation of the excited state and the length of the shaping medium on the two-photon absorption is discussed. Based on the dispersion theory the oscillation of the transient two-photon transition is explained. The result indicates that the transition probability of two-photon absorption evolves regularly with the several values of parameters such as the length of medium (l), relaxation time (t2 ) and bandwidth ( △ω). Meanwhile the transition probability appears in the transient oscillation.%研究了小激光脉冲面积光场与三能级原子系统的相互作用过程,分析了整形脉冲的形成机理与特征,讨论了能级弛豫以及整形介质长度等参量对输出光场的影响.依据色散理论,分析了瞬态双光子跃迁几率的振荡现象.结果表明:随着介质长度(l)、频宽(△w)和弛豫时间(t2)等参量的变化,瞬态双光子跃迁几率发生有规律的变化,同时出现跃迁几率的瞬时振荡现象.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. Investigation of changes in the spherical shell shape under the action of pulsed loading due to contact interaction with a rigid block

    Science.gov (United States)

    Bazhenov, V. G.; Varavin, D. A.; Kibets, A. I.; Ryabov, A. A.; Romanov, V. I.

    2015-11-01

    An axisymmetric problem of high strains in a spherical lead shell enclosed into an aluminum "spacesuit" under the action of pulsed loading is considered. The shell straining is described with the use of equations of mechanics of elastoviscoplastic media in Lagrangian variables, and the kinematic relations are determined in the current state metrics. Equations of state are taken in the form of equations of the flow theory with isotropic hardening. The problem is solved numerically by using the variational difference method and the "cross" explicit scheme of integration with respect to time. The influence of the yield stress as a function of the strain rate on changes in the shell shape is studied for different values of loading. The calculated final shape and residual strains are demonstrated to be in good agreement with experimental data.

  20. 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

    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...

  1. Laser pulse shaping for optimal control of multiphoton dissociation in a diatomic molecule using genetic algorithm optimization

    International Nuclear Information System (INIS)

    Graphical abstract: Application of genetic algorithm optimization to control dissociation process in the ground electronic state of HF molecule is demonstrated. Highlights: ► Genetic algorithm optimization for the design of laser pulses. ► Control of dissociation process in the ground electronic state of HF molecule. ► Two types of pulses, one with fixed frequency components and the other having non-deterministic components. ► 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.

  2. 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.

  3. 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.

  4. Pulse shape discrimination studies with a Broad-Energy Germanium detector for signal identification and background suppression in the GERDA double beta decay experiment

    CERN Document Server

    Budjáš, Dušan; Chkvorets, Oleg; Khanbekov, Nikita; Schönert, Stefan

    2009-01-01

    First studies of event discrimination with a Broad-Energy Germanium (BEGe) detector are presented. A novel pulse shape method, exploiting the characteristic electrical field distribution inside BEGe detectors, allows to identify efficiently single-site events and to reject multi-site events. The first are typical for neutrinoless double beta decays (0-nu-2-beta) and the latter for backgrounds from gamma-ray interactions. The obtained survival probabilities of backgrounds at energies close to Q(76Ge) = 2039 keV are 0.93% for events from 60Co, 21% from 226Ra and 40% from 228Th. This background suppression is achieved with 89% acceptance of 228Th double escape events, which are dominated by single site interactions. Approximately equal acceptance is expected for 0-nu-2-beta-decay events. Collimated beam and Compton coincidence measurements demonstrate that the discrimination is largely independent of the interaction location inside the crystal and validate the pulse-shape cut in the energy range of Q(76Ge). The ...

  5. 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

    enable very low light-emitting diode (LED) driving currents for the pulse oximeter. The photodiode also have a two layer SiO2/SiN interference filter yielding 98% transmission at the measuring wavelengths, 660 nm and 940 nm, and suppressing other wavelengths down to 50% transmission. The photodiode has...... 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....

  6. LiNbO3强度调制器的光脉冲整形应用%The application of LiNb03 intensity modulator in optical pulse shaping

    Institute of Scientific and Technical Information of China (English)

    赵灏; 谢征; 吕宏伟; 徐明阳; 欧阳竑; 刘芳

    2011-01-01

    The optical pulse generation system (FD) needs to ouput optical pulse shaped preliminary. The electro-optic modulator can satisfy this application preferably. A method to shape optical pulse is designed according to the characteristic of LiNbO3 intensity modulator. One stage LiNbO3 intensity modulator is used in this application aad the ouput DC extinction ratio is better than 36dB.The shaped optical pulses at about nanosecood such as a square pulse and a concavity pulse and others are created. The contrast of concavity pulse is bettr than 1O0:1.%光脉冲产生系统(前端系统)需要输出初步整形的光脉冲,电光调制器可以较好地满足该需求.根据LiNbO3强度调制器特性,设计出一种整形方法,采用一级LiNbO3强度调制器进行输出光脉冲整形,可使输出直流消光比优于36dB,可生成纳秒级方波、凹型等整形光脉冲,凹型脉冲对比度优于100:1.

  7. Transient microwave bandwidth measurements of illuminated silicon switches for optical pulse-shape control of laser-fusion drivers

    International Nuclear Information System (INIS)

    The microwave transmission properties of a high-purity (≥40 kΩ·cm) single-crystal-silicon, photoconductive (PC) switch were measured while the switch was optically activated. The switch was 2.3 mm wide (the width of the microstrip electrode), 2 mm long, and 0.5 mm thick with a 0.5-mm photoconductive gap and was mounted in a 50-Ω microstrip transmission line. The switch was irradiated uniformly with a 150-ns FWHM pulse from a ND:YAG laser (wavelength = 1.064 microm). The insertion loss of the optically activated PC switch was a nearly constant -0.7 dB across the measurement system bandwidth (9 GHz). Under these illumination conditions, the switch exhibited negligible bandwidth limitations. The microstrip structure by itself had an insertion loss that increased from -0.4 dB at 1 GHz to -1.4 dB at 9 GHz

  8. Coupling electromagnetic pulse-shaped waves into wire-like interconnection structures with a non-linear protection – Time domain calculations by the PEEC method

    Directory of Open Access Journals (Sweden)

    G. Wollenberg

    2004-01-01

    Full Text Available An interconnection system whose loads protected by a voltage suppressor and a low-pass filter against overvoltages caused by coupling pulse-shaped electromagnetic waves is analyzed. The external wave influencing the system is assumed as a plane wave with HPM form. The computation is provided by a full-wave PEEC model for the interconnection structure incorporated in the SPICE code. Thus, nonlinear elements of the protection circuit can be included in the calculation. The analysis shows intermodulation distortions and penetrations of low frequency interferences caused by intermodulations through the protection circuits. The example examined shows the necessity of using full-wave models for interconnections together with non-linear circuit solvers for simulation of noise immunity in systems protected by nonlinear devices.

  9. Transmission and full-band coherent detection of polarization-multiplexed all-optical Nyquist signals generated by Sinc-shaped Nyquist pulses.

    Science.gov (United States)

    Zhang, Junwen; Yu, Jianjun; Chi, Nan

    2015-09-01

    All optical method is considered as a promising technique for high symbol rate Nyquist signal generation, which has attracted a lot of research interests for high spectral-efficiency and high-capacity optical communication system. In this paper, we extend our previous work and report the fully experimental demonstration of polarization-division multiplexed (PDM) all-optical Nyquist signal generation based on Sinc-shaped Nyquist pulse with advanced modulation formats, fiber-transmission and single-receiver full-band coherent detection. Using this scheme, we have successfully demonstrated the generation, fiber transmission and single-receiver full-band coherent detection of all-optical Nyquist PDM-QPSK and PDM-16QAM signals up to 125-GBaud. 1-Tb/s single-carrier PDM-16QAM signal generation and full-band coherent detection is realized, which shows the advantage and feasibility of the single-carrier all-optical Nyquist signals.

  10. Signal-signal beat interference cancellation in spectrally-efficient WDM direct-detection Nyquist-pulse-shaped 16-QAM subcarrier modulation.

    Science.gov (United States)

    Li, Zhe; Erkılınç, M Sezer; Pachnicke, Stephan; Griesser, Helmut; Bouziane, Rachid; Thomsen, Benn C; Bayvel, Polina; Killey, Robert I

    2015-09-01

    An experimental demonstration of direct-detection single-sideband Nyquist-pulse-shaped 16-QAM subcarrier modulated (Nyquist-SCM) transmission implementing a receiver-based signal-signal beat interference (SSBI) cancellation technique is described. The performance improvement with SSBI mitigation, which compensates for the nonlinear distortion caused by square-law detection, was quantified by simulations and experiments for a 7 × 25 Gb/s WDM Nyquist-SCM signal with a net optical information spectral density (ISD) of 2.0 (b/s)/Hz. A reduction of 3.6 dB in the back-to-back required OSNR at the HD-FEC threshold was achieved. The resulting reductions in BER in single channel and WDM transmission over distances of up to 800 km of uncompensated standard single-mode fiber (SSMF) achieved are presented.

  11. Use Of Pulsed IR Thermography For Determination Of Size And Depth Of Subsurface Defect Taking Into Account The Shape Of Its Cross-Section Area

    Directory of Open Access Journals (Sweden)

    Wysocka-Fotek O.

    2015-06-01

    Full Text Available The paper is devoted to reconstruction of size and depth (distance from the tested surface of artificial defects with square and rectangular cross-section areas using the pulsed IR thermography. Defects in form of flat-bottom holes were made in austenitic steel plate. The defect size was estimated on the basis of surface distribution of the time derivative of the temperature. In order to asses the depth of defects with considered geometries on the basis of calibration relations (i.e. dependence of time of contrast maximum vs. defect depth for given defect diameter obtained for circular defects, the ‘equivalent diameter’ describing not only the defect cross-section area but also its shape was assigned. It has been shown that presented approach gives satisfactory results.

  12. Fermi Study of gamma-ray Millisecond Pulsars: the Spectral Shape and Pulsed 25--200 GeV Emission from J0614-3329

    CERN Document Server

    Xing, Yi

    2016-01-01

    We report our analysis of the Fermi Large Area Telescope data for 39 millisecond pulsars (MSPs) listed in the second $\\gamma$-ray pulsar catalog. Spectra of the pulsars are obtained. We fit the spectra with a function of a power law with exponential cutoff, and find the best-fit parameters of photon index $\\Gamma = 1.54^{+0.10}_{-0.11}$ and cutoff energy $E_{c} = 3.70^{+0.95}_{-0.70}$ GeV. This spectral shape, which includes the intrinsic differences in the spectra of the MSPs, can be used for finding candidate MSPs and unidentified types of sources detected by Fermi at high Galactic latitudes. In one of the MSPs PSR J0614-3329, we find significant pulsed emission upto 200 GeV. The result has thus added this MSP to the group of the Crab and Vela pulsars that have been detected with >50 GeV pulsed emission. Comparing the $\\gamma$-ray spectrum of PSR J0614-3329 with those of the Crab and Vela pulsars, we discuss possible emission mechanisms for the very high-energy component.

  13. Search for the neutrinoless double β-decay in GERDA phase I using a pulse shape discrimination technique

    International Nuclear Information System (INIS)

    The Germanium Detector Array (Gerda) experiment, located underground at the INFN Laboratori Nazionali del Gran Sasso (LNGS) in Italy, deploys high-purity germanium detectors to search for the neutrinoless double β-decay (0νββ) of 76Ge. An observation of this lepton number violating process, which is expected by many extensions of the Standard Model, would not only generate a fundamental shift in our understanding of particle physics, but also unambiguously prove the neutrino to have a non-vanishing Majorana mass component. A first phase of data recording lasted from November 2011 to May 2013 - resulting in a total exposure (defined as the product of detector mass and measurement time) of 21.6 kg.yr. Within this thesis a thorough study of this data with special emphasis on the development and scrutiny of an active background suppression technique by means of a signal shape analysis has been performed. Among several investigated multivariate approaches, particularly a selection algorithm based on an artificial neural network is found to yield the best performance; i.a. the background index close to the Q-value of the 0νββ-decay could be suppressed by 45% to 1.10-2 cts/(keV.kg.yr), while still retaining a considerably high signal survival fraction of (83±3)% leading to a significant improvement of the experimental sensitivity. The efficiency is derived by a simulation and further validated by substantiated consistency checks availing themselves of measurements taken with different calibration sources and physics data. No signal is observed and a new lower limit of T0ν1/2 (90%C.L.)> 2.2. 1025 yr for the half-life of neutrinoless double β-decay of 76Ge is established.

  14. Search for the neutrinoless double β-decay in GERDA phase I using a pulse shape discrimination technique

    Energy Technology Data Exchange (ETDEWEB)

    Kirsch, Andrea

    2014-07-09

    The Germanium Detector Array (Gerda) experiment, located underground at the INFN Laboratori Nazionali del Gran Sasso (LNGS) in Italy, deploys high-purity germanium detectors to search for the neutrinoless double β-decay (0νββ) of {sup 76}Ge. An observation of this lepton number violating process, which is expected by many extensions of the Standard Model, would not only generate a fundamental shift in our understanding of particle physics, but also unambiguously prove the neutrino to have a non-vanishing Majorana mass component. A first phase of data recording lasted from November 2011 to May 2013 - resulting in a total exposure (defined as the product of detector mass and measurement time) of 21.6 kg.yr. Within this thesis a thorough study of this data with special emphasis on the development and scrutiny of an active background suppression technique by means of a signal shape analysis has been performed. Among several investigated multivariate approaches, particularly a selection algorithm based on an artificial neural network is found to yield the best performance; i.a. the background index close to the Q-value of the 0νββ-decay could be suppressed by 45% to 1.10{sup -2} cts/(keV.kg.yr), while still retaining a considerably high signal survival fraction of (83±3)% leading to a significant improvement of the experimental sensitivity. The efficiency is derived by a simulation and further validated by substantiated consistency checks availing themselves of measurements taken with different calibration sources and physics data. No signal is observed and a new lower limit of T{sup 0ν}{sub 1/2} (90%C.L.)> 2.2. 10{sup 25} yr for the half-life of neutrinoless double β-decay of {sup 76}Ge is established.

  15. Pulse-shape analysis of signals from monolithic silicon E-{delta}E telescopes produced by the quasi-selective epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Kordyasz, A.J. [Heavy Ion Laboratory, Warsaw University, ul. Pasteura 5a, 02-093 Warszawa (Poland)]. E-mail: kord@slcj.uw.edu.pl; Iwanicki, J. [Heavy Ion Laboratory, Warsaw University, ul. Pasteura 5a, 02-093 Warszawa (Poland); Kowalczyk, M. [Heavy Ion Laboratory, Warsaw University, ul. Pasteura 5a, 02-093 Warszawa (Poland); Kulczycka, E. [Heavy Ion Laboratory, Warsaw University, ul. Pasteura 5a, 02-093 Warszawa (Poland); Nossarzewska-Orlowska, E. [Institute of Electronic Materials Technology, Warsaw (Poland); Lipinski, D. [Institute of Electronic Materials Technology, Warsaw (Poland); Brzozowski, A. [Institute of Electronic Materials Technology, Warsaw (Poland)

    2006-12-01

    Two monolithic E-{delta}E charged particle telescopes with {delta}E layers of 11 and 20{mu}m thick, respectively, produced with the Quasi-Selective Epitaxy method were tested at the Heavy Ion Laboratory in Warsaw. Thorium source {alpha}-particles and {sup 12}C({sup 14}N,X) reaction products at 80MeV beam energy were used. During on-beam tests, detectors were placed at 20{sup -}bar laboratory angle with respect to the beam axis. Among the reaction products, ions of Li, Be, B, C, N, O, F were identified (using the telescope with 20{mu}m{delta}E layer). Pulses from both E and {delta}E components of the telescope were digitalized with a digital oscilloscope, sent to a PC machine and recorded. Pulse shape analysis technique was then applied to obtain the final two dimensional spectrum. The E-{delta}E two-dimensional scatter plots obtained after irradiation of the monolithic E-{delta}E telescopes by {alpha}-particles from the calibration source are presented. The energy resolution of the monolithic E-{delta}E telescope measured using {alpha}-particles was about 0.7MeV for telescope with 20{mu}m thick {delta}E layer and 0.4MeV for telescope with 11{mu}m{delta}E layer. Response of the monolythic E-{delta}E telescopes for Po212 8.78MeV {alpha}-particles registered at different impact positions at the telescope face was measured. Cross-talk signals in the monolithic E-{delta}E telescope as a function of position and the {delta}E detector capacitance were simulated using the numerical solution of the telegraphic equation describing time-dependent evolution of the cross-talk potentials in the {delta}E detector RC network.

  16. Pulse shape discrimination properties of plastic scintillators incorporating a rationally designed highly soluble and polymerizable derivative of 9,10-diphenylanthracene

    Science.gov (United States)

    Hajagos, Tibor Jacob; Kishpaugh, David; Pei, Qibing

    2016-07-01

    A highly soluble and polymerizable derivative of 9,10-diphenylanthracene was designed and synthesized specifically to be capable of achieving very high loadings (at least 50 wt.%) when copolymerized with a polyvinyltoluene (PVT) matrix. The resulting heavily crosslinked plastics are mechanically hard and robust, and were found to have exceptional clarity with no sign of dye precipitation. Samples of these plastics both with and without added wavelength shifter were characterized for light yield, scintillation decay, and pulse shape discrimination (PSD) performance for α / γ discrimination, and the results were compared to that of a commercially available PSD plastic, EJ-299-34. The best performing formulation, with a primary dye loading of 50 wt.%, had a measured light yield of 9950 photons/MeV, and achieved a PSD figure-of-merit (FOM) of 1.05, the latter indicating that while the present material is not suited for practical applications, the overall approach demonstrates a proof-of-concept of PSD in highly loaded plastics stabilized through copolymerization of the primary dye, and suggests that further improvements through better dye choice/design may yet be achievable.

  17. Highly efficient photocatalysis by BiFeO{sub 3}/{alpha}({gamma})-Fe{sub 2}O{sub 3} ferromagnetic nano p/n junctions formed by dopant-induced phase separation

    Energy Technology Data Exchange (ETDEWEB)

    Ramadan, Wegdan, E-mail: wegdan.ramadan@gmail.com [Alexandria University, Physics Department, Faculty of Science (Egypt); Shaikh, Parvez A. [National Chemical Laboratory (CSIR-NCL), Council of Scientific and Industrial Research (India); Ebrahim, Sh. [Alexandria University, Materials Science Department, Institute of Graduate Studies and Research (Egypt); Ramadan, Abdallah [Alexandria University, Physics Department, Faculty of Science (Egypt); Hannoyer, Beatrice; Jouen, Samuel; Sauvage, Xavier [Universite de Rouen, GPM, UMR 6634 CNRS (France); Ogale, Satishchandra, E-mail: sb.ogale@ncl.res.in [National Chemical Laboratory (CSIR-NCL), Council of Scientific and Industrial Research (India)

    2013-08-15

    A series of Bi{sub 1-x}Ca{sub x}FeO{sub 3} (BCFO) nanoparticles (with x = 0.0, 0.03, 0.07, 0.10, 0.15, and 0.20) have been synthesized by sol-gel reaction. X-ray diffraction patterns establish the formation of hexagonal bismuth ferrite as the prominent phase, with a small contribution of the Bi{sub 2}Fe{sub 4}O{sub 9} phase (as reported by others as well) which diminishes rapidly with the increase in Ca concentration. Interestingly, above a calcium dopant concentration of about 10 % peaks of Fe{sub 2}O{sub 3} (both {alpha} and {gamma} components) are observed with a concomitant enhancement of ferromagnetism. Small contribution of the Bi{sub 6}Ca{sub 4}O{sub 13} phase is also noted in these samples. This phase evolution is driven by dopant-induced strain energy and increasing oxygen vacancy concentration for local charge balance. Transmission electron microscopy (with elemental scanning) and Moessbauer spectroscopy techniques bring out the evolution of nanoparticle morphology (and elemental distribution) and phase configuration, respectively. Measurements of photocatalytic activity (and photo-Fenton activity with H{sub 2}O{sub 2}) reveal that Ca doping at the Bi site in BFO enhances the activity significantly in the concentration regime where BFO/{alpha}({gamma})-Fe{sub 2}O{sub 3} phases coexist in the form of a nanocomposite. The enhancement can thus be attributed to the carrier transfer between BFO and {alpha}({gamma})-Fe{sub 2}O{sub 3} across nano p/n junctions leading to enhanced carrier lifetime. Importantly, the magnetization of the nanocomposite (about 16 emu gm{sup -1} at x = 0.20) provides a convenient way to collect the photocatalyst with the help of an external magnet for reuse.

  18. 钟罩式脉冲澄清池的技术改造%Technical transformation of bell-shape pulse clarifier

    Institute of Scientific and Technical Information of China (English)

    王雪峰

    2013-01-01

    For the purpose of meeting the requirements of industrial water for 2 500 m3 blast furnace,the second reconstruction of 1# bell-shape pulse clarifier was carried out from aspects of process,civil construction,electric system,and so on.The reconstruction engineering adopted a combination process of pipe static mixer-folded-plate flocculating tank-inclined-tube sedimentation tank.Through the reconstruction,the design water yield recovered to 2500 m3/h,the mass concentration of the SS and turbidity in the effluent water from coagulation sedimentation tank were lower than 20 mg/L and 10 NTU respectively,which indicated that,the quality and quantity of the effluent water could meet the requirement of the production water supply system of the plant with newly added equipments.%为满足新建2500 m3高炉工业用水要求,将1#钟罩式脉冲澄清池从工艺、土建、电气等各方面着手进行二次改造.改造流程采用管道静态混合器-折板絮凝池-斜管沉淀池工艺组合方式.改造后设计产水量恢复到2500 m3/h,混凝沉淀池出水SS的质量浓度低于20 mg/L,浊度低于10 NTU,出水水质、水量能够满足厂内新增设备后生产用水要求.

  19. Pulse on Pulse

    DEFF Research Database (Denmark)

    Schmidt, Ulrik; Carlson, Merete

    2012-01-01

    Pulse on Pulse” investigates the relation between signifying processes and non-signifying material dynamism in the installation Pulse Room (2006-) by Mexican Canadian artist Rafael Lozano-Hemmer. In Pulse Room the sense of pulse is ambiguous. Biorhythms are transmitted from the pulsing energy...

  20. Evaluation of granulated BGO, GSO:Ce, YAG:Ce, CaF sub 2 :Eu and ZnS:Ag for alpha/beta pulse shape discrimination in a flow-cell radiation detector

    CERN Document Server

    Devol, T A; Fjeld, R A

    1999-01-01

    Granulated BGO, GSO:Ce, YAG:Ce, and CaF sub 2 :Eu; CaF sub 2 :Eu coated with a fluorescent polymer, and combinations of coated and uncoated CaF sub 2 :Eu with ZnS:Ag were evaluated for their ability to discriminate between alpha and beta particles in a flow-cell radiation detector. The evaluations were based on the analysis of pulse shape spectra. Various granulated scintillators were packed into flow cell detectors that were coils of 3.0 mm ODx1.5 mm ID fluorinated ethylene propylene Teflon[reg] tubing positioned between dual photomultiplier tubes for analysis. The best pulse shape discrimination was obtained for a combination of equal masses of uncoated CaF sub 2 :Eu (63-90 mu m) and ZnS:Ag (10 mu m), which had a 9% spillover. Additional research is needed to reduce the spillover.

  1. Influence of a step-tapered undulator field on the optical pulse shape of a far-infrared free-electron laser

    NARCIS (Netherlands)

    Knippels, G.M.H.; van der Meer, A. F. G.; Mols, Rfxam; Oepts, D.; van Amersfoort, P. W.; Jaroszynski, D. A.

    1996-01-01

    The optical output of the free-electron laser for infrared experiments (FELIX), which operates in the regime of strong slippage, consists of picosecond pulses, Depending on the amount of cavity desynchronization, the optical pulse can develop substantial structure in the form of multiple subpulses,

  2. Neutron-induced background by an alpha-beam incident on a deuterium gas target and its implications for the study of the 2H(alpha,gamma)6Li reaction at LUNA

    CERN Document Server

    Anders, M; Bellini, A; Aliotta, M; Bemmerer, D; Broggini, C; Caciolli, A; Costantini, H; Corvisiero, P; Davinson, T; Elekes, Z; Erhard, M; Formicola, A; Fülöp, Zs; Gervino, G; Guglielmetti, A; Gustavino, C; Gyürky, Gy; Junker, M; Lemut, A; Marta, M; Mazzocchi, C; Menegazzo, R; Prati, P; Alvarez, C Rossi; Scott, D; Somorjai, E; Straniero, O; Szücs, T

    2013-01-01

    The production of the stable isotope Li-6 in standard Big Bang nucleosynthesis has recently attracted much interest. Recent observations in metal-poor stars suggest that a cosmological Li-6 plateau may exist. If true, this plateau would come in addition to the well-known Spite plateau of Li-7 abundances and would point to a predominantly primordial origin of Li-6, contrary to the results of standard Big Bang nucleosynthesis calculations. Therefore, the nuclear physics underlying Big Bang Li-6 production must be revisited. The main production channel for Li-6 in the Big Bang is the 2H(alpha,gamma)6Li reaction. The present work reports on neutron-induced effects in a high-purity germanium detector that were encountered in a new study of this reaction. In the experiment, an {\\alpha}-beam from the underground accelerator LUNA in Gran Sasso, Italy, and a windowless deuterium gas target are used. A low neutron flux is induced by energetic deuterons from elastic scattering and, subsequently, the 2H(d,n)3He reaction....

  3. Switchable dual-pulse-shape mode-locked figure-eight all-PM fibre master oscillator with 0.5 W-level average output

    Science.gov (United States)

    Kobtsev, Sergey; Ivanenko, Aleksey; Fedotov, Yurii; Smirnov, Sergey V.; Golubtsov, Artur; Khripunov, Sergey

    2016-03-01

    For the first time a method for switching between generation of single- and double-scale pulses has been demonstrated in a mode-locked figure-eight NALM-based all-PM-fibre Yb master oscillator by adjustment of two pumps power. Introduction into a F8 configuration of a non-linear amplifying loop mirror with two active media not only ensured relatively high average output power of the master oscillator (> 0.5 W at 22-MHz repetition rate), but also allowed switching laser operation from one pulse type (single-scale with duration of <10 ps) to another - femtosecond clusters with envelope width of 16 ps and sub-pulse duration <200 fs.

  4. DogPulse

    DEFF Research Database (Denmark)

    Skovgaard, Christoffer; Thomsen, Josephine Raun; Verdezoto, Nervo;

    2015-01-01

    This paper presents DogPulse, an ambient awareness system to support the coordination of dog walking among family members at home. DogPulse augments a dog collar and leash set to activate an ambient shape-changing lamp and visualize the last time the dog was taken for a walk. The lamp gradually c...

  5. Neutron-induced background by an {alpha}-beam incident on a deuterium gas target and its implications for the study of the {sup 2}H({alpha},{gamma}){sup 6}Li reaction at LUNA

    Energy Technology Data Exchange (ETDEWEB)

    Anders, M.; Bemmerer, D.; Elekes, Z.; Marta, M. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Trezzi, D.; Mazzocchi, C. [INFN, Sezione di Milano, Milano (Italy); Bellini, A.; Costantini, H.; Corvisiero, P.; Lemut, A.; Prati, P. [Universita di Genova (Italy); INFN, Sezione di Genova, Dipartimento di Fisica, Genova (Italy); Aliotta, M.; Davinson, T.; Scott, D. [University of Edinburgh, SUPA, School of Physics and Astronomy, Edinburgh (United Kingdom); Broggini, C.; Caciolli, A.; Erhard, M.; Menegazzo, R.; Rossi Alvarez, C. [INFN, Sezione di Padova, Padova (Italy); Formicola, A.; Junker, M. [Laboratori Nazionali del Gran Sasso, INFN, Assergi (Italy); Fueloep, Zs.; Gyuerky, G.; Somorjai, E.; Szuecs, T. [Institute of Nuclear Research (ATOMKI), Debrecen (Hungary); Gervino, G. [Universita di Torino (Italy); INFN, Dipartimento di Fisica Sperimentale, Torino (Italy); Guglielmetti, A. [INFN, Sezione di Milano, Milano (Italy); Universita degli Studi di Milano, Milano (Italy); Gustavino, C. [INFN, Sezione di Roma ' ' La Sapienza' ' , Roma (Italy); Straniero, O. [INFN, Sezione di Napoli, Napoli (Italy); Osservatorio Astronomico di Collurania, Teramo (Italy); Collaboration: LUNA Collaboration

    2013-02-15

    The production of the stable isotope {sup 6}Li in standard Big Bang nucleosynthesis has recently attracted much interest. Recent observations in metal-poor stars suggest that a cosmological {sup 6}Li plateau may exist. If true, this plateau would come in addition to the well-known Spite plateau of {sup 7}Li abundances and would point to a predominantly primordial origin of {sup 6}Li, contrary to the results of standard Big Bang nucleosynthesis calculations. Therefore, the nuclear physics underlying Big Bang {sup 6}Li production must be revisited. The main production channel for {sup 6}Li in the Big Bang is the {sup 2}H({alpha},{gamma}){sup 6}Li reaction. The present work reports on neutron-induced effects in a high-purity germanium detector that were encountered in a new study of this reaction. In the experiment, an {alpha}-beam from the underground accelerator LUNA in Gran Sasso, Italy, and a windowless deuterium gas target are used. A low neutron flux is induced by energetic deuterons from elastic scattering and, subsequently, the {sup 2}H(d,n){sup 3}He reaction. Due to the ultra-low laboratory neutron background at LUNA, the effect of this weak flux of 2-3 MeV neutrons on well-shielded high-purity germanium detectors has been studied in detail. Data have been taken at 280 and 400keV {alpha}-beam energy and for comparison also using an americium-beryllium neutron source. (orig.)

  6. Theoretical analysis of pulse modulation of semiconductor lasers

    Energy Technology Data Exchange (ETDEWEB)

    Xu Baoxi; Zhan Yushu; Guo Siji

    1987-05-01

    Rate equations of Gaussian shape pulse modulated semiconductor lasers are solved by Runge--Kutta method, and the results are analyzed. The formulae for calculating the delay time, pulse width of laser pulse and maximum bit-rate of Gaussian shape pulse modulation are derived. The experimental results of modulation pattern effects are given.

  7. Pulse distortion in single-mode fibers. 3: Chirped pulses.

    Science.gov (United States)

    Marcuse, D

    1981-10-15

    The theory of pulse distortion in single-mode fibers is extended to include laser sources that suffer a linear wavelength sweep (chirp) during the duration of the pulse. The transmitted pulse is expressed as a Fourier integral whose spectral function is given by an analytical expression in closed form. The rms width of the transmitted pulse is also expressed in closed form. Numerical examples illustrate the influence of the chirp on the shape and rms width of the pulse. A somewhat paradoxical situation exists. A given input pulse can be made arbitrarily short by a sufficiently large amount of chirping, and, after a given fiber length, this chirped pulse returns to its original width. But at this particular distance an unchirped pulse would be only [equiation] times longer. Thus chirping can improve the rate of data transmission by only 40%.

  8. Pulse distortion in single-mode fibers. 3: Chirped pulses.

    Science.gov (United States)

    Marcuse, D

    1981-10-15

    The theory of pulse distortion in single-mode fibers is extended to include laser sources that suffer a linear wavelength sweep (chirp) during the duration of the pulse. The transmitted pulse is expressed as a Fourier integral whose spectral function is given by an analytical expression in closed form. The rms width of the transmitted pulse is also expressed in closed form. Numerical examples illustrate the influence of the chirp on the shape and rms width of the pulse. A somewhat paradoxical situation exists. A given input pulse can be made arbitrarily short by a sufficiently large amount of chirping, and, after a given fiber length, this chirped pulse returns to its original width. But at this particular distance an unchirped pulse would be only [equiation] times longer. Thus chirping can improve the rate of data transmission by only 40%. PMID:20372221

  9. 一种改进DA算法的成型滤波器设计%Pulse shaping filter design based on improved DA algorithm

    Institute of Scientific and Technical Information of China (English)

    吴凤辉; 迟永钢; 郑宇希; 杨木

    2016-01-01

    In order to meet the requirement of high⁃speed and high⁃order shaping filter design, an improved DA ( Distributed Architecture ) algorithm is proposed on the basis of the traditional DA method. Considering zero insertion using in up⁃sampling process, Look⁃Up⁃Table is employed instead of ROM ( Read⁃Only Memory ) for reducing the number of effective address and increasing addressing speed. The proposed algorithm takes advantage of tables segmentation and symmetry of filter coefficients to save storage resource and improve processing speed. Meanwhile, pipeline contracture is further exploited to achieve better performance. Compared with commercial finite impulse response filter IP core, the proposed algorithm not only realizes higher rate as well as reduces the utilization of logic resources effectively, but also can design high⁃order filter without limit of ROM in hardware.%针对高速、高阶成型滤波器的实现问题,在传统分布式DA算法的基础上,提出一种改进算法。利用升采样过程中内插零的结构特点,使用逻辑单元LUT代替存储ROM,减少了有效地址位数,提高了寻址速度;利用表分割算法和滤波器系数的对称性,并通过增加流水线结构,进一步节约了存储资源的消耗,提升了运算速度。通过与商用FIR IP核( DA算法)的实测对比,所提算法最大实现速率有所提高,且在高阶滤波器设计时不受硬件ROM大小和数量的限制,有效改善了逻辑资源的使用情况。

  10. Spatial dispersion of pulse shaping system with high resolution based on the frequency comb%光学频率梳空间光谱分辨精度研究

    Institute of Scientific and Technical Information of China (English)

    王楠; 韩海年; 李德华; 魏志义

    2012-01-01

    High resolution pulse shaping based on the frequency comb has been widely used in microwave photonics, spectroscopy and communication optics and so on. To describe and evaluate the resolution capability of such a pulse shaping system, the ray tracing method is adopted to analyze the spatial dispersions of four schemes like single grating, parallel gratings, single grating with focus and anti-parallel gratings with focus. The spot spacings and sizes of different wavelengths can be determined from the modeling. As indicated by the calculation results, the latter two structures are advantageous to achieve high resolution pulse shaping; frequency combs with long wavelength, large mode spacing and big spot size are favorable for space dispersion; high grating groove density, small incident angle and multi passes in the dispersion system are conducible to the achievement of high resolution. The criterion for resolution would bring on some spot overlap noise.%光学频率梳的高精度光谱整形在微波光子学、光谱学及通信光学等学科领域具有广泛应用.为了描述和评价光学频率梳光谱整形系统的光谱分辨精度,使用光线追迹的方法对单光栅、平行光栅对、单光栅透镜变换和反平行光栅对透镜变换四种结构的空间色散能力进行了理论建模和分析,得到了输出面上不同波长的光斑间距和光斑大小,设立判据得到系统的光谱空间分离能力.计算结果表明,使用后面两种色散结构更容易实现高精度光谱分离和整形:波长较长、纵模间距较大、光斑尺寸较大的光学频率梳更适合作为光谱整形系统的光源;光栅刻线密度高、入射角小、多次通过色散系统有利于得到更高的光谱分辨精度.本文的分析和计算过程具有普遍适用性,对基于光学频率梳的高精度光谱整形系统的实验和评价具有指导意义.

  11. 基于并联SOA的全光广播式超宽带脉冲形状调制技术%Research on all-optical broadcasting ultra-wideband pulse shape modulation based on multiple semiconductor optical amplifiers

    Institute of Scientific and Technical Information of China (English)

    马晓璐; 李培丽; 郑加金; 张一; 朱天阳

    2013-01-01

    基于半导体光放大器(SOA)中交叉增益调制(XGM)效应,采用SOA的并联结构,提出了一种全光产生广播式超宽带(UWB)脉冲形状调制(PSM)信号的方案.该方案同时产生三路超宽带PSM信号,具有多用户传输数据的能力,可为多址通信作理论基础;采用相向的工作方式可以改善输出信号的消光比.利用OptiSystem7.0软件对方案进行仿真,分析了输入信号脉冲宽度、输入光功率和波长对产生的超宽带PSM信号的影响,对信号的传输特性进行了研究.结果表明,本文方案对输入信号脉冲宽度和输入光波长具有良好的容忍度,并且给出了输入光功率的优化范围.%An all-optical broadcasting ultra-wideband (UWB) pulse shape modulation (PSM) technology based on the cross-gain modulation (XGM) in a semiconductor optical amplifier (SOA) has been demonstrated.In this novel scheme,two wideband traveling wave SOAs are used,and the structure of the parallel SOAs is adopted to generate the PSM signals.and three kinds of ultra-wideband PSM signals are generated at the smae time.As a consequence,this new scheme has the ability to transmit data among multiple users,and can be used as a theoretical basis of multiple accuess communication.As the opposite working way is used.the scheme has an advantage in improving the extinction ratio (ER) of the output three ultra-wideband PSM signals.By using the software of OptiSystem7.0,the impacts of the input signal pulse width,the optical power and the wavelength of the laser on the generated three kinds of ultrawideband PSM signal are numberically simulated and studied.In addition,the transmission characteristics of the generated PSM signal are discussed.The results show that the PSM signal has a good toleration to the pulse width,and the optimized ranges of other parameters are presented.

  12. Band-selective radiofrequency pulses

    Science.gov (United States)

    Geen, Helen; Freeman, Ray

    A theoretical treatment is given of the general problem of designing amplitude-modulated radiofrequency pulses that will excite a specified band of frequencies within a high-resolution NMR spectrum with uniform intensity and phase but with negligible excitation elsewhere. First a trial pulse envelope is defined in terms of a finite Fourier series and its frequency-domain profile calculated through the Bloch equations. The result is compared with the desired target profile to give a multidimensional error surface. The method of simulated annealing is then used to find the global minimum on this surface and the result refined by standard gradient-descent optimization. In this manner, a family of new shaped radio-frequency pulses, known as BURP ( band-selective, uniform response, pure-phase) pulses, has been created. These are of two classes—pulses that excite or invert z magnetization and those that act as general-rotation πr/2 or π pulses irrespective of the initial condition of the nuclear magnetization. It was found convenient to design the latter class as amplitude-modulated time-symmetric pulses. Tables of Fourier coefficients and pulse-shape ordinates are given for practical implementation of BURP pulses, together with the calculated frequency-domain responses and experimental verifications. Examples of the application of band-selective pulses in conventional and multidimensional spectroscopy are given. Pure-phase pulses of this type should also find applications in magnetic resonance imaging where refocusing schemes are undesirable.

  13. Laser system using ultra-short laser pulses

    Science.gov (United States)

    Dantus, Marcos; Lozovoy, Vadim V.; Comstock, Matthew

    2009-10-27

    A laser system using ultrashort laser pulses is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and binary pulse shaping (BPS). Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal.

  14. Analog pulse processor

    Science.gov (United States)

    Wessendorf, Kurt O.; Kemper, Dale A.

    2003-06-03

    A very low power analog pulse processing system implemented as an ASIC useful for processing signals from radiation detectors, among other things. The system incorporates the functions of a charge sensitive amplifier, a shaping amplifier, a peak sample and hold circuit, and, optionally, an analog to digital converter and associated drivers.

  15. 400 Gbit/s single-carrier and 1 Tbit/s three-carrier superchannel signals using dual polarization 16-QAM with look-up table correction and optical pulse shaping.

    Science.gov (United States)

    Ke, Jian Hong; Gao, Ying; Cartledge, John C

    2014-01-13

    A 448 Gbit/s single-carrier dual-polarization 16-ary quadrature-amplitude-modulation (DP 16-QAM) signal and a 1.206 Tbit/s three-carrier DP 16-QAM signal are demonstrated using look-up table (LUT) correction and optical pulse shaping. The LUT correction is used to mitigate the effects of transmitter-based pattern-dependent distortion due to the high symbol rates. A programmable optical filter is employed to narrow the modulated signal spectrum and thereby enhance the spectral efficiency and reduce the requirements on the receiver bandwidth and analog-to-digital converter sampling rate. By combining these techniques, the back-to-back required optical signal-to-noise ratios are 26.6 dB and 27.2 dB for BER = 10(-3), and transmission over 1200 and 1500 km of standard single-mode fiber with EDFA amplification was achieved for the 448 Gbit/s signal (12% forward error correction (FEC) overhead) and 1.206 Tbit/s signal (20% FEC overhead), respectively. PMID:24514967

  16. Longitudinal Laser Shaping in Laser Wakefield Accelerators

    OpenAIRE

    Spitkovsky, Anatoly; Chen, Pisin

    2000-01-01

    We study the energetics of wake excitation during the laser-plasma interaction in application to laser wakefield accelerators. We find that both the wake amplitude and the accelerating efficiency (transformer ratio) can be maximized by properly shaping the longitudinal profile of the driving laser pulse. The corresponding family of laser pulse shapes is derived in the nonlinear regime of laser-plasma interaction. Such shapes provide theoretical upper limit on the magnitude of the wakefield an...

  17. Intraband effects on ultrafast pulse propagation in semiconductor optical amplifier

    Indian Academy of Sciences (India)

    K Hussain; S K Varshney; P K Datta

    2010-11-01

    High bit-rate (>10 Gb/s) signals are composed of very short pulses and propagation of such pulses through a semiconductor optical amplifier (SOA) requires consideration of intraband phenomena. Due to the intraband effects, the propagating pulse sees a fast recovering nonlinear gain which introduces less distortion in the pulse shape and spectrum of the output pulse but introduces a positive chirping at the trailing edge of the pulse.

  18. High order coherent control sequences of fat pulses

    CERN Document Server

    Pasini, S; Uhrig, G S

    2010-01-01

    We analyze the performance of sequences of fat pulses of various lengths and shapes for dynamic decoupling and we compare it with that of sequences of ideal, instantaneous pulses. The use of second order, shaped pulses represents a significant improvement. Non-equidistant sequences characterized by pulse durations scaled proportional to the duration T of the sequence strikingly outperform the sequences with pulses of constant length for small T. Interestingly, for longer durations sequences of pulses of substantial length are found to suppress dephasing better than sequences of ideal pulses.

  19. Coiled transmission line pulse generators

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, Kenneth Fox (Columbia, MO)

    2010-11-09

    Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

  20. Generation And Measurement Of High Contrast Ultrashort Intense Laser Pulses

    CERN Document Server

    Konoplev, O A

    2000-01-01

    In this thesis, the generation and measurement of high contrast, intense, ultrashort pulses have been studied. Various factors affecting the contrast and pulse shape of ultrashort light pulses from a chirped pulse amplification (CPA) laser system are identified. The level of contrast resulting from influence of these factors is estimated. Methods for improving and controlling the pulse shape and increasing the contrast are discussed. Ultrahigh contrast, 1-ps pulses were generated from a CPA system with no temporal structure up to eleven orders of magnitude. This is eight orders of magnitude higher contrast than the original pulse. This contrast boost was achieved using two techniques. One is the optical pulse cleaning based on the nonlinear birefringence of the chirping fiber and applied to the pulses before amplification. The other is the fast saturable absorber. The fast saturable absorber was placed after amplification and compression of the pulse. The measurements of high-contrast, ultrashort pulse with h...

  1. Electron trajectories in pulsed radiation fields

    International Nuclear Information System (INIS)

    The work reported here analyzes the dynamical behavior of an electron, initially at rest, when subjected to a radiation pulse of arbitrary, but integrable, shape. This is done by a general integration procedure that has been programmed in VAXIMA. Upon choosing a specific shape for the pulse, VAXIMA finds both the space-time trajectory and the four-momentum of the electron. These are obtained in analytic or numerical form - or both - at the choice of the user. Several examples of analytical and numerical solutions, for different pulse shapes, are given

  2. Efficient chirped-pulse amplification of sub-20 fs laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Matsuoka, Shinichi; Yamakawa, Koichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    We have developed a model for ultrabroadband and ultrashort pulse amplification including the effects of a pulse shaper for regenerative pulse shaping, gain narrowing and gain saturation in the amplifiers. Thin solid etalons are used to control both gain narrowing and gain saturation during amplification. This model has been used to design an optimized Ti:sapphire amplifier system for producing efficiently pulses of < 20-fs duration with approaching peak and average powers of 100 TW and 20 W. (author)

  3. Compensation of pulse-distortion in saturated laser amplifiers.

    Science.gov (United States)

    Schimpf, Damian N; Ruchert, Clemens; Nodop, Dirk; Limpert, Jens; Tünnermann, Andreas; Salin, Francois

    2008-10-27

    We derive an expression describing pre-compensation of pulse-distortion due to saturation effects in short pulse laser-amplifiers. The analytical solution determines the optimum input pulse-shape required to obtain any arbitrary target pulse-shape at the output of the saturated laser-amplifier. The relation is experimentally verified using an all-fiber amplifier chain that is seeded by a directly modulated laser-diode. The method will prove useful in applications of high power, high energy laser-amplifier systems that need particular pulse-shapes to be efficient, e.g. micromachining and scientific laser-matter-interactions. PMID:18958044

  4. Pulse Voltammetry.

    Science.gov (United States)

    Osteryoung, Janet

    1983-01-01

    Discusses the nature of pulse voltammetry, indicating that its widespread use arises from good sensitivity and detection limits and from ease of application and low cost. Provides analytical and mechanistic applications of the procedure. (JN)

  5. Filters for High Rate Pulse Processing

    OpenAIRE

    Alpert, B. K.; Horansky, R. D.; Bennett, D.A.; Doriese, W. B.; Fowler, J. W.; Hoover, A. S.; Rabin, M. W.; Ullom, J. N.

    2012-01-01

    We introduce a filter-construction method for pulse processing that differs in two respects from that in standard optimal filtering, in which the average pulse shape and noise-power spectral density are combined to create a convolution filter for estimating pulse heights. First, the proposed filters are computed in the time domain, to avoid periodicity artifacts of the discrete Fourier transform, and second, orthogonality constraints are imposed on the filters, to reduce the filtering procedu...

  6. Nanosecond pulse generators for induction linear accelerators

    International Nuclear Information System (INIS)

    The paper reviews five different circuits of nanosecond pulse generators for induction linear accelerators. Hydrogen thyratrons which feature a good stability of parameters in time are used as switches. Short voltage pulses (1 - 5 ns) are shaped using nonlinear ferromagnetic lines.The voltage amplitude range on inductor excitation turns is 20-50 kV. 6 refs., 6 figs., 1 tab

  7. Electric pulse generator with a saturable inductance

    International Nuclear Information System (INIS)

    Power supply of induction accelerators is obtained with a pulse generator comprising a coaxial line shaping the pulses and magnetic compression means feeding this line with a capacitor and a saturable inductance, inside the line. A conductor is connected to the end of the inductance and to the median part of the internal electrode and a magnetic commutator discharging the line

  8. Pulse interaction in nonlinear vacuum electrodynamics

    OpenAIRE

    Ignatov, A. M.; Poponin, V. P.

    2000-01-01

    The energy-momentum conservation law is used to investigate the interaction of pulses in the framework of nonlinear electrodynamics with Lorentz-invariant constitutive relations. It is shown that for the pulses of the arbitrary shape the interaction results in phase shift only.

  9. Training Ultrafast Laser Pulses

    Science.gov (United States)

    Averin, Ruslan; Wells, N.; Todt, M.; Smolnisky, N.; Jastram, N.; Jochim, B.; Gregerson, N.; Wells, E.; Sayler, A.; McKenna, J.; Carnes, K.; Ben-Itzhak, I.; Kling, M. F.

    2009-11-01

    Closed loop control of molecular processes utilizing shaped ultrafast laser pulses has been around for a number of years, yet this type of control has primarily utilized Time of Flight ion yield data for feedback. We present experiments using Velocity Map Imaging (VMI) as the feedback source for the closed loop control. Using VMI allows for pulse optimization not only with respect to the disassociation species but also angular information of the final state. We demonstrate the feasibility of incorporating this kind of feedback into the control loop. Using this technique, we controlled the dissociation branching ratio of CO^+ into C^+ +O or C ^+O^+ and used the VMI information to recover additional information about the control mechanism.

  10. Pulse plating

    CERN Document Server

    Hansal, Wolfgang E G; Green, Todd; Leisner, Peter; Reichenbach, Andreas

    2012-01-01

    The electrodeposition of metals using pulsed current has achieved practical importance in recent years. Although it has long been known that changes in potential, with or without polarity reversal, can significantly affect the deposition process, the practical application of this has been slow to be adopted. This can largely be explained in terms of the complex relationship between the current regime and its effect on the electrodeposition process. In order to harness these effects, an understanding of the anodic and cathodic electrochemical processes is necessary, together with the effects of polarity reversal and the rate of such reversals. In this new monograph, the basics of metal electrodeposition from solution are laid out in great detail in seven distinct chapters. With this knowledge, the reader is able to predict how a given pulse train profile can be adopted to achieve a desired outcome. Equally important is the choice of a suitable rectifier and the ancillary control circuits to enable pulse platin...

  11. Quantum-state-preserving optical frequency conversion and pulse reshaping by four-wave mixing

    DEFF Research Database (Denmark)

    McKinstrie, C. J.; Andersen, Lasse Mejling; Raymer, M. G.;

    2012-01-01

    Nondegenerate four-wave mixing driven by two pulsed pumps transfers the quantum state of an input signal pulse to an output idler pulse, which is a frequency-converted and reshaped version of the signal. By varying the pump shapes appropriately, one can connect signal and idler pulses with arbitr......Nondegenerate four-wave mixing driven by two pulsed pumps transfers the quantum state of an input signal pulse to an output idler pulse, which is a frequency-converted and reshaped version of the signal. By varying the pump shapes appropriately, one can connect signal and idler pulses...

  12. Compression of chirp pulses from a femtosecond fiber based amplifier

    Science.gov (United States)

    Ito, Rumi; Takiuchi, Ken-ichi; Tei, Kazuyoku; Yamaguchi, Shigeru; Enokidani, Jyun; Sumida, Shin

    2015-03-01

    We demonstrate a single mode fiber based master oscillator power amplifier (MOPA) with a single polarization and a fully monolithic design. We have built a passive mode-locked polarization maintaining Yb doped fiber as the master oscillator contains a semiconductor saturable absorber mirror and a chirped fiber Bragg grating for the dispersion management. The net intracavity dispersion was managed to be slightly anomalous. The oscillator generates the 150 fs (sech2) pulses at the center wavelength of 1065 nm, and the repetition rate of 42 MHz. The oscillator output was amplified to 1.4 W from 80 mW in the single stage fiber amplifier which results in pulse shape distortion. The pulse shaping with a band pass filter and a compressor was applied to the amplified pulses. The shaping pulses have the pulse width of 90 fs and the pulse energy of 16 nJ.

  13. Dependence of adiabatic population transfer on pulse profile

    Indian Academy of Sciences (India)

    S Dasgupta; T kushwaha; D Goswami

    2006-06-01

    Control of population transfer by rapid adiabatic passage has been an established technique wherein the exact amplitude profile of the shaped pulse is considered to be insignificant. We study the effect of ultrafast shaped pulses for two-level systems, by density-matrix approach. However, we find that adiabaticity depends simultaneously on pulse profile as well as the frequency modulation under non-resonant conditions.

  14. 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.

  15. What causes the superluminal propagation of light pulses

    Institute of Scientific and Technical Information of China (English)

    ShiYao Zhu(朱诗尧); LiGang Wang(王立刚)

    2003-01-01

    In this paper, we discuss what causes the superluminal propagation of a pulse through dispersion by solving Maxwell's equations without any approximation. The coherence of the pulse plays an important role for superluminal propagation. When the pulse becomes partially coherent, the propagation changes from superluminal to subluminal. The energy velocity is always less than the vacuum velocity. The shape of the pulse is changed during the propagation.

  16. Theoertical investigation of quantum waveform shaping for single photon emitters.

    Science.gov (United States)

    Pedrotti, Leno M; Agha, Imad

    2016-07-25

    We investigate a new technique for quantum-compatible waveform shaping that extends the time lens method, and relies only on phase operations. Under realistic experimental conditions, we show that it is possible to both temporally compress and shape optical waveforms in the nanosecond to tens of picoseconds range, which is generally difficult to achieve using standard dispersive pulse-shaping techniques. PMID:27464122

  17. A method to obtain pulse contrast on a single shot

    Institute of Scientific and Technical Information of China (English)

    Xiaoping Ouyang; Xiaoyan Li; Yanli Zhang; Zhaoyang Li; Guang Xu; Tao Wang; Baoqiang Zhu; Jianqiang Zhu

    2009-01-01

    @@ A novel method for obtaining a single shot multi-point high dynamic range pulse contrast measurement is presented.We use Dammann gratings to generate multiple beamlets by division of amplitude on ultra-short laser pulses.The analysis results show that this method can achieve high dynamic range in pulse contrast measurement on a single shot by using photomultiplier tube (PMT) detectors and the long work-ing distances to minimize cross talk between channels.Some distortion of pulse shape is also analyzed detailedly with the Dammann grating and its compensation grating, which may degrade the pulse contrast measurement in some degree by pulse stretching and spectrum clipping.

  18. The Pulse Scale Conjecture and the Case of BATSE Trigger 2193

    OpenAIRE

    Nemiroff, Robert J.

    2000-01-01

    The pulses that compose gamma-ray bursts (GRBs) are hypothesized to have the same shape at all energies, differing only by scale factors in time and amplitude. This "Pulse Scale Conjecture" is confirmed here between energy channels of the dominant pulse in GRB 930214c (BATSE trigger 2193), the single most fluent single-pulsed GRB that occurred before May 1998. Furthermore, pulses are hypothesized to start at the same time independent of energy. This "Pulse Start Conjecture" is also confirmed ...

  19. Pulse radiolysis

    International Nuclear Information System (INIS)

    This supplement to two bibliographies published in 1970 and 1972 lists 734 references to the literature of pulse radiolysis, arranged under eight broad subject headings. The references were compiled by searching Biological Abstracts, Chemical Abstracts, Nuclear Science Abstracts and the Weekly List of Papers in Radiation Chemistry issued by the Radiation Chemistry Data Center of Notre Dame University. Full bibliographic data is given for papers published in the period 1971 to 1974. A personal author index listing more than 600 authors and a similar number of co-authors is included

  20. PULSE COLUMN

    Science.gov (United States)

    Grimmett, E.S.

    1964-01-01

    This patent covers a continuous countercurrent liquidsolids contactor column having a number of contactor states each comprising a perforated plate, a layer of balls, and a downcomer tube; a liquid-pulsing piston; and a solids discharger formed of a conical section at the bottom of the column, and a tubular extension on the lowest downcomer terminating in the conical section. Between the conical section and the downcomer extension is formed a small annular opening, through which solids fall coming through the perforated plate of the lowest contactor stage. This annular opening is small enough that the pressure drop thereacross is greater than the pressure drop upward through the lowest contactor stage. (AEC)

  1. Increasing voltage of high power electric pulses by means of a pulse transformer

    Energy Technology Data Exchange (ETDEWEB)

    Vdovin, S.S.

    1985-07-01

    The production of megavolt and terawatt electric pulses is difficult and complex. A component part of this problem is increasing the voltage of power pulses of the primary generators used. The problem of increasing the voltage of these pulses can be solved by the use of pulse transformers. However, due to the great voltages and power involved, it is necessary to establish the possibility in principle of increasing voltages to several megavolts, as well as the suitability of the technical and economic characteristics of pulse transformers designed for these purposes. Calculations performed in this article indicate that with pulse lengths of over 1 microsecond, pulse transformers can yield sufficiently high voltages with very slight distortions of transformed pulse shape and power losses. The use of pulse transformers is therefore effective and expedient at pulse lengths of over 1 microsecond. At lengths of less than 0.02 microsecond, pulse transformers apparently became undesirable due to low pulse voltages, great peak distortions and low efficiency.

  2. Nonlinear pulse compression of picosecond parabolic-like pulses synthesized with a long period fiber grating filter.

    Science.gov (United States)

    Krcmarík, David; Slavík, Radan; Park, Yongwoo; Azaña, José

    2009-04-27

    tract: We demonstrate high quality pulse compression at high repetition rates by use of spectral broadening of short parabolic-like pulses in a normally-dispersive highly nonlinear fiber (HNLF) followed by linear dispersion compensation with a conventional SMF-28 fiber. The key contribution of this work is on the use of a simple and efficient long-period fiber grating (LPFG) filter for synthesizing the desired parabolic-like pulses from sech(2)-like input optical pulses; this all-fiber low-loss filter enables reducing significantly the required input pulse power as compared with the use of previous all-fiber pulse re-shaping solutions (e.g. fiber Bragg gratings). A detailed numerical analysis has been performed in order to optimize the system's performance, including investigation of the optimal initial pulse shape to be launched into the HNLF fiber. We found that the pulse shape launched into the HNLF is critically important for suppressing the undesired wave breaking in the nonlinear spectral broadening process. The optimal shape is found to be independent on the parameters of normally dispersive HNLFs. In our experiments, 1.5-ps pulses emitted by a 10-GHz mode-locked laser are first reshaped into 3.2-ps parabolic-like pulses using our LPFG-based pulse reshaper. Flat spectrum broadening of the amplified initial parabolic-like pulses has been generated using propagation through a commercially-available HNLF. Pulses of 260 fs duration with satellite peak and pedestal suppression greater than 17 dB have been obtained after the linear dispersion compensation fiber. The generated pulses exhibit a 20-nm wide supercontinuum energy spectrum that has almost a square-like spectral profile with >85% of the pulse energy contained in its FWHM spectral bandwidth.

  3. Nonlinear pulse compression of picosecond parabolic-like pulses synthesized with a long period fiber grating filter.

    Science.gov (United States)

    Krcmarík, David; Slavík, Radan; Park, Yongwoo; Azaña, José

    2009-04-27

    tract: We demonstrate high quality pulse compression at high repetition rates by use of spectral broadening of short parabolic-like pulses in a normally-dispersive highly nonlinear fiber (HNLF) followed by linear dispersion compensation with a conventional SMF-28 fiber. The key contribution of this work is on the use of a simple and efficient long-period fiber grating (LPFG) filter for synthesizing the desired parabolic-like pulses from sech(2)-like input optical pulses; this all-fiber low-loss filter enables reducing significantly the required input pulse power as compared with the use of previous all-fiber pulse re-shaping solutions (e.g. fiber Bragg gratings). A detailed numerical analysis has been performed in order to optimize the system's performance, including investigation of the optimal initial pulse shape to be launched into the HNLF fiber. We found that the pulse shape launched into the HNLF is critically important for suppressing the undesired wave breaking in the nonlinear spectral broadening process. The optimal shape is found to be independent on the parameters of normally dispersive HNLFs. In our experiments, 1.5-ps pulses emitted by a 10-GHz mode-locked laser are first reshaped into 3.2-ps parabolic-like pulses using our LPFG-based pulse reshaper. Flat spectrum broadening of the amplified initial parabolic-like pulses has been generated using propagation through a commercially-available HNLF. Pulses of 260 fs duration with satellite peak and pedestal suppression greater than 17 dB have been obtained after the linear dispersion compensation fiber. The generated pulses exhibit a 20-nm wide supercontinuum energy spectrum that has almost a square-like spectral profile with >85% of the pulse energy contained in its FWHM spectral bandwidth. PMID:19399083

  4. PULSE REFERENCED CONTROL METHOD FOR ENHANCED POWER AMPLIFICATION OF A PULSE MODULATED SIGNAL

    DEFF Research Database (Denmark)

    1998-01-01

    To correct for any source of non-linearity and noise introduced in the power amplification of a pulse modulated signal, a correction unit is applied in-between the pulse modulator and the switching power amplification stage. The correction unit is controlled to have a compensating effect, by...... introducing continuous delays on the individual pulse edges on the basis of error information provided by an error processing block. One preferred embodiment of the invention comprises: a Correction Unit with means to control the delays of the individual pulse edges as a function of a control input signal $i......(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...

  5. Modeling Pulse Characteristics in Xenon with NEST

    CERN Document Server

    Mock, Jeremy; Kazkaz, Kareem; Szydagis, Matthew; Tripathi, Mani; Uvarov, Sergey; Woods, Michael; Walsh, Nicholas

    2013-01-01

    A comprehensive model for describing the characteristics of pulsed signals, generated by particle interactions in xenon detectors, is presented. An emphasis is laid on two-phase time projection chambers, but the models presented are also applicable to single phase detectors. In order to simulate the pulse shape due to primary scintillation light, effects such as the ratio of singlet and triplet dimer state populations, as well as their corresponding decay times, and the recombination time are incorporated into the model. In a two phase time projection chamber, when simulating the pulse caused by electroluminescence light, parameters such as ionization electron mean free path in gas, the drift velocity, singlet and triplet decay times, diffusion constants, and the electron trapping time, have been implemented. This modeling has been incorporated into a complete software package, which realistically simulates the expected pulse shapes for these types of detectors.

  6. Modeling pulse characteristics in Xenon with NEST

    Science.gov (United States)

    Mock, J.; Barry, N.; Kazkaz, K.; Stolp, D.; Szydagis, M.; Tripathi, M.; Uvarov, S.; Woods, M.; Walsh, N.

    2014-04-01

    A comprehensive model for describing the characteristics of pulsed signals, generated by particle interactions in xenon detectors, is presented. An emphasis is laid on two-phase time projection chambers, but the models presented are also applicable to single phase detectors. In order to simulate the pulse shape due to primary scintillation light, the effects of the ratio of singlet and triplet dimer state populations, as well as their corresponding decay times, and the recombination time are incorporated into the model. In a two phase time projection chamber, when simulating the pulse caused by electroluminescence light, the ionization electron mean free path in gas, the drift velocity, singlet and triplet decay times, diffusion constants, and the electron trapping time, have been implemented. This modeling has been incorporated into a complete software package, which realistically simulates the expected pulse shapes for these types of detectors.

  7. Quantum-state-preserving optical pulse reshaping and multiplexing by four-wave mixing in a fiber

    DEFF Research Database (Denmark)

    McKinstrie, C. J.; Andersen, Lasse Mejling; Rottwitt, Karsten;

    2012-01-01

    Nondegenerate four-wave mixing driven by two pulsed pumps transfers the quantum state of an input signal pulse to an output idler pulse, which is a frequency-translated and reshaped version of the signal. By varying the pump shapes appropriately, one can connect signal and idler pulses with arbit......Nondegenerate four-wave mixing driven by two pulsed pumps transfers the quantum state of an input signal pulse to an output idler pulse, which is a frequency-translated and reshaped version of the signal. By varying the pump shapes appropriately, one can connect signal and idler pulses...

  8. Optical pulse generation system for the National Ignition Facility (NIF)

    Energy Technology Data Exchange (ETDEWEB)

    Penko, F; Braucht,; Browning, D; Crane, J K; Dane, B; Deadrick, F; Dreifuerst, G; Henesian, M; Jones, B A; Kot, L; Laumann, C; Martinez, M; Moran, B; Rothenberg, J E; Skulina, K; Wilcox, R B

    1998-06-18

    We describe the Optical Pulse Generation (OPG) system for the National Ignition Facility ( NIF ). The OPG system begins with the Master Oscillator Room ( MOR ) where the initial, seed pulse for the entire laser system is produced and properly formatted to enhance ignition in the target. The formatting consists of temporally shaping the pulse and adding additional bandwidth to increase the coupling of the laser generated x-rays to the high density target plasma. The pulse produced in the MOR fans out to 48 identical preamplifier modules where it is amplified by a factor of ten billion and spatially shaped for injection into the 192 main amplifier chai

  9. Dynamics of formation of optoacoustic pulses of the first and second sound in He-II, excited by a rectangular pulse of laser radiation by the thermal mechanism

    International Nuclear Information System (INIS)

    A theory of generation of optoacoustic pulses of first and second sound in superfluid helium by the rectangular pulse of laser radiation generated by thermal mechanism was considered. It was found that all of the exciting pulses are formed in competition pulses generated at turning on and off the beam and have opposite phases. Numerical results showed that all generated optoacoustic pulses have bipolar shape.

  10. Single-pulse stimulated Raman scattering spectroscopy

    CERN Document Server

    Frostig, Hadas; Natan, Adi; Silberberg, Yaron

    2010-01-01

    We demonstrate the acquisition of stimulated Raman scattering spectra with the use of a single femtosecond pulse. High resolution vibrational spectra are obtained by shifting the phase of a narrow band of frequencies in the broadband input pulse spectrum, using spectral shaping. The vibrational spectrum is resolved by examining the amplitude features formed in the spectrum after interaction with the sample. Using this technique, low frequency Raman lines (<100cm^-1) are resolved in a straightforward manner.

  11. Efficient cloning and dragging of microwave pulse into optical frequency pulse in a Doppler-broadened atomic medium

    CERN Document Server

    V., Rajitha K

    2015-01-01

    The propagation of a weak optical pulse through an atomic system in closed $\\Lambda$ configuration is investigated in which the hyper fine levels are coupled by a microwave pulse. Under three photon resonance condition, it is observed that the probe pulse shape gets cloned by the shape of the microwave pulse along propagation through the medium. The temporal position of the probe pulse is dragged to that of the microwave pulse. A simple expression for the linear susceptibility of the medium for the corresponding transition is derived in the Fourier domain. From the numerical analysis of dynamics using this expression, it is concluded that the novel effect arises from the ground state coherence of the hyper fine transitions induced by the microwave pulse.

  12. Mathematical modeling of the optimum pulse structure for safe and effective photo epilation using broadband pulsed light.

    Science.gov (United States)

    Ash, Caerwyn; Donne, Kelvin; Daniel, Gwenaelle; Town, Godfrey; Clement, Marc; Valentine, Ronan

    2012-09-06

    The objective of this work is the investigation of intense pulsed light (IPL) photoepilation using Monte Carlo simulation to model the effect of the output dosimetry with millisecond exposure used by typical commercial IPL systems. The temporal pulse shape is an important parameter, which may affect the biological tissue response in terms of efficacy and adverse reactions. This study investigates the effect that IPL pulse structures, namely free discharge, square pulse, close, and spaced pulse stacking, has on hair removal. The relationship between radiant exposure distribution during the IPL pulse and chromophore heating is explored and modeled for hair follicles and the epidermis using a custom Monte Carlo computer simulation. Consistent square pulse and close pulse stacking delivery of radiant exposure across the IPL pulse is shown to generate the most efficient specific heating of the target chromophore, whilst sparing the epidermis, compared to free discharge and pulse stacking pulse delivery. Free discharge systems produced the highest epidermal temperature in the model. This study presents modeled thermal data of a hair follicle in situ, indicating that square pulse IPL technology may be the most efficient and the safest method for photoepilation. The investigation also suggests that the square pulse system design is the most efficient, as energy is not wasted during pulse exposure or lost through interpulse delay times of stacked pulses.

  13. Pulse distortion in single-mode fibers.

    Science.gov (United States)

    Marcuse, D

    1980-05-15

    A theory is presented of the propagation of Gaussian pulses in single-mode optical fibers by expanding the propagation constant in a Taylor series that includes the third derivative with respect to frequency. The light source is assumed to have a Gaussian spectral distribution whose width relative to the width of the Gaussian signal pulse is arbitrary. Formulas are derived for the spectrum of the ensemble average of the optical pulse, from which the shape of the average pulse itself is obtained by the fast Fourier transform. Also derived is an expression for the rms pulse width. The theory is applicable at all wavelengths including the vicinity of the zero first-order dispersion point.

  14. Excimer Laser Pulse Compress With Pulse Feedback

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>To attain a shorter laser pulse, a compressing technique called pulse feedback was developed from the saturation gain switch applied to the amplification in a discharge pumping excimer laser cavity. It can

  15. Gaussian shaping filter for nuclear spectrometry

    International Nuclear Information System (INIS)

    A theorical study of a gaussian shaping filter, using Pade approximation, for using in gamma spectroscopy is presented. This approximation has proved superior to the classical cascade RC integrators approximation in therms of signal-to-noise ratio and pulse simmetry. An experimental filter was designed, simulated in computer, constructed, and tested in the laboratory. (author)

  16. Compensating for inconsistent high power vircator microwave radar pulse sources

    Science.gov (United States)

    McAulay, Alastair D.

    2012-06-01

    We investigate a vircator as an economical high power pulsed microwave source for radar. Because of the inconsistency of spark gaps in the driver and operation of the tube based vircator, the resulting ringing pulse has a different pulse shape each time a pulse is generated. Therefore every time we pulse the source we must remove the effects of the ringing source pulse from the data resulting from that pulse. Scattering from a scene is considered random (white noise) with a superimposed non-white component due to the pulse. We propose a whitening filter to remove the effects of the ringing pulse from the random data. This produces a similar result as spectral factorization in which we first determine the pulse from the power spectrum of the data and then deconvolve the ringing pulse out of the received data. The removal of pulse specific ringing increases range resolution and allows data from sequential pulses from a single vircator or pulses from separate vircators to be combined for joint processing in a synthetic aperture radar.

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

    CERN Document Server

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

    2016-01-01

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

  18. Pulse Evolution Characteristics in Self-Similar Mode-locked Fibre Laser

    Institute of Scientific and Technical Information of China (English)

    TU Cheng-Hou; LI Zhen; LEI Ting; LI Yong-Nan; GUO Wen-Gang; WEI Dai; ZHU Hui; ZHANG Shuang-Gen; LU Fu-Yun

    2007-01-01

    A self-similar mode locked fibre laser is studied based on a numerical model. By introducing a dimensionless factor k to characterize the pulse shape, the self-similar pulse evolution, formation and the temporal and spectral shape changes due to the elements in the cavity are investigated throughout the iaser cavity. The results show that in the self-similar mode locked fibre laser, self-similar pulse is first formed in the single-mode fibre, which is then amplified in the gain fibre. Gain bandwidth has a small influence on pulse shape, so high energy self-similar pulse can be obtained after amplification. Because net cavity dispersion directly influences the pulse width as well as peak power after compression by a pair of gratings, which can determine the pulse self-similar evolution, it is very important to control the net cavity dispersion to a certain range to obtain self-similar pulses.

  19. An improved rolled strip pulse forming line

    Science.gov (United States)

    Li, Song; Qian, Bao-Liang; Yang, Han-Wu; Gao, Jing-Ming; Liu, Zhao-Xi

    2013-06-01

    The rolled strip pulse forming line (RSPFL) has advantages of compactness, portability, and long pulse achievability which could well meet the requirements of industrial application of the pulse power technology. In this paper, an improved RSPFL with an additional insulator between the grounded conductors is investigated numerically and experimentally. Results demonstrate that the jitter on the flat-top of the output voltage waveform is reduced to 3.8% due to the improved structure. Theoretical analysis shows that the electromagnetic coupling between the conductors of the RSPFL strongly influences the output voltage waveform. Therefore, the new structure was designed to minimize the detrimental effect of the electromagnetic coupling. Simulation results show that the electromagnetic coupling can be efficiently reduced in the improved RSPFL. Experimental results illustrate that the improved RSPFL, with dimensions and weight of Φ 290 × 250 mm and 16 kg, when used as a simple pulse forming line, could generate a well shaped quasi-square pulse with output power of hundreds of MW and pulse duration of 250 ns. Importantly, the improved RSPFL was successfully used as a Blumlein pulse forming line, and a 10.8 kV, 260 ns quasi-square pulse was obtained on a 2 Ω dummy load. Experiments show reasonable agreement with numerical analysis.

  20. Polarization sensitive anisotropic structuring of silicon by ultrashort light pulses

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jingyu; Drevinskas, Rokas, E-mail: rd1c12@orc.soton.ac.uk; Beresna, Martynas; Kazansky, Peter G. [Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ (United Kingdom)

    2015-07-27

    Imprinting of anisotropic structures on the silicon surface by double pulse femtosecond laser irradiation is demonstrated. The origin of the polarization-induced anisotropy is explained in terms of interaction of linearly polarized second pulse with the wavelength-sized symmetric crater-shaped structure generated by the linearly polarized first pulse. A wavefront sensor is fabricated by imprinting an array of micro-craters. Polarization controlled anisotropy of the structures can be also explored for data storage applications.

  1. High-power pulse trains excited by modulated continuous waves

    OpenAIRE

    Wang, Yan; Song, Lijun; Li, Lu; Malomed, Boris A.

    2015-01-01

    Pulse trains growing from modulated continuous waves (CWs) are considered, using solutions of the Hirota equation for solitons on a finite background. The results demonstrate that pulses extracted from the maximally compressed trains can propagate preserving their shape and forming robust arrays. The dynamics of double high-power pulse trains produced by modulated CWs in a model of optical fibers, including the Raman effect and other higher-order terms, is considered in detail too. It is demo...

  2. Nonsequential Double Ionization of Atoms in Strong Laser Pulses

    Science.gov (United States)

    Prauzner-Bechcicki, J. S.; Sacha, K.; Eckhardt, B.; Zakrzewski, J.

    2007-10-01

    It is now possible to produce laser pulses with reproducible pulse shape and controlled carrier envelope phase. It is discussed how that can be explored in double ionisation studies. To this end we solve numerically the Schrödinger equation for a limited dimensionality model which nevertheless treats electron repulsion qualitatively correctly and allows to study correlation effects due to the Coulomb repulsion.

  3. Inductive Pulse Generation

    OpenAIRE

    Lindblom, Adam

    2006-01-01

    Pulsed power generators are a key component in compact systems for generation of high-power microwaves (HPM). HPM generation by virtual cathode devices such as Vircators put high demands on the source. The rise time and the pulse length of the source voltage are two key issues in the generation of HPM radiation. This thesis describes the construction and tests of several inductive high power pulse generators. The pulse generators were designed with the intent to deliver a pulse with fast rise...

  4. Pulse Propagation on close conductors

    CERN Document Server

    Dieckmann, A

    2001-01-01

    The propagation and reflection of arbitrarily shaped pulses on non-dispersive parallel conductors of finite length with user defined cross section is simulated employing the discretized telegraph equation. The geometry of the system of conductors and the presence of dielectric material determine the capacities and inductances that enter the calculation. The values of these parameters are found using an iterative Laplace equation solving procedure and confirmed for certain calculable geometries including the line charge inside a box. The evolving pulses and the resulting crosstalk can be plotted at any instant and - in the Mathematica notebook version of this report - be looked at in an animation. As an example a differential pair of microstrips as used in the ATLAS vertex detector is analysed.

  5. Cross section measurements of the sup 1 sup 0 sup 2 Pd(p, gamma) sup 1 sup 0 sup 3 Ag, sup 1 sup 1 sup 6 Sn(p, gamma) sup 1 sup 1 sup 7 Sb, and sup 1 sup 1 sup 2 Sn(alpha, gamma) sup 1 sup 1 sup 6 Te reactions relevant to the astrophysical rp- and gamma-processes

    CERN Document Server

    Oezkan, N; Boyd, R N; Cole, A L; Famiano, M; Gueray, R T; Howard, M; Sahin, L; Zach, J J; Haan, R D; Görres, J; Wiescher, M C; Islam, M S; Rauscher, T

    2002-01-01

    Total cross section measurements for the sup 1 sup 0 sup 2 Pd(p, gamma) sup 1 sup 0 sup 3 Ag and sup 1 sup 1 sup 6 Sn(p, gamma) sup 1 sup 1 sup 7 Sb reactions have been performed in the proton energy range 2.6 to 4.25 MeV, and for the sup 1 sup 1 sup 2 Sn(alpha, gamma) sup 1 sup 1 sup 6 Te reaction over the alpha beam energy range 7.0 to 10.5 MeV. An activation technique was used in which gamma rays from decays of the reaction products were detected off-line by two hyper-pure germanium detectors in a low background environment. Where possible, reaction rates are derived and the results compared to those of calculations generated by the NON-SMOKER and the MOST statistical model codes so as to judge their applicability for describing the cross sections needed for network calculations of nucleosynthesis in explosive astrophysical environments via the gamma- and rp-processes.

  6. A Novel Transcranial Magnetic Stimulator Inducing Near Rectangular Pulses with Controllable Pulse Width (cTMS)

    Science.gov (United States)

    Jalinous, Reza; Lisanby, Sarah H.

    2013-01-01

    A novel transcranial magnetic stimulation (TMS) device with controllable pulse width (PW) and near rectangular pulse shape (cTMS) is described. The cTMS device uses an insulated gate bipolar transistor (IGBT) with appropriate snubbers to switch coil currents up to 7 kA, enabling PW control from 5 μs to over 100 μs. The near-rectangular induced electric field pulses use 22–34% less energy and generate 67–72% less coil heating compared to matched conventional cosine pulses. CTMS is used to stimulate rhesus monkey motor cortex in vivo with PWs of 20 to 100 μs, demonstrating the expected decrease of threshold pulse amplitude with increasing PW. The technological solutions used in the cTMS prototype can expand functionality, and reduce power consumption and coil heating in TMS, enhancing its research and therapeutic applications. PMID:18232369

  7. A transcranial magnetic stimulator inducing near-rectangular pulses with controllable pulse width (cTMS).

    Science.gov (United States)

    Peterchev, Angel V; Jalinous, Reza; Lisanby, Sarah H

    2008-01-01

    A novel transcranial magnetic stimulation (TMS) device with controllable pulse width (PW) and near-rectangular pulse shape (cTMS) is described. The cTMS device uses an insulated gate bipolar transistor (IGBT) with appropriate snubbers to switch coil currents up to 6 kA, enabling PW control from 5 micros to over 100 micros. The near-rectangular induced electric field pulses use 2%-34% less energy and generate 67%-72% less coil heating compared to matched conventional cosine pulses. CTMS is used to stimulate rhesus monkey motor cortex in vivo with PWs of 20 to 100 micros, demonstrating the expected decrease of threshold pulse amplitude with increasing PW. The technological solutions used in the cTMS prototype can expand functionality, and reduce power consumption and coil heating in TMS, enhancing its research and therapeutic applications. PMID:18232369

  8. Limits of Femtosecond Fiber Amplification by Parabolic Pre-Shaping

    CERN Document Server

    Fu, Walter; McComb, Timothy S; Lowder, Tyson L; Wise, Frank W

    2016-01-01

    We explore parabolic pre-shaping as a means of generating and amplifying ultrashort pulses. We develop a theoretical framework for modeling the technique and use its conclusions to design a femtosecond fiber amplifier. Starting from 9 ps pulses, we obtain 4.3 $\\mu$J, nearly transform-limited pulses 275 fs in duration, simultaneously achieving over 40 dB gain and 33-fold compression. Finally, we show that this amplification scheme is limited by Raman scattering, and outline a method by which the pulse duration and energy may be further improved and tailored for a given application.

  9. DIFFERENTIAL PULSE HEIGHT DISCRIMINATOR

    Science.gov (United States)

    Test, L.D.

    1958-11-11

    Pulse-height discriminators are described, specifically a differential pulse-height discriminator which is adapted to respond to pulses of a band of amplitudes, but to reject pulses of amplitudes greater or less than tbe preselected band. In general, the discriminator includes a vacuum tube having a plurality of grids adapted to cut off plate current in the tube upon the application of sufficient negative voltage. One grid is held below cutoff, while a positive pulse proportional to the amplltude of each pulse is applled to this grid. Another grid has a negative pulse proportional to the amplitude of each pulse simultaneously applied to it. With this arrangement the tube will only pass pulses which are of sufficlent amplitude to counter the cutoff bias but not of sufficlent amplitude to cutoff the tube.

  10. Propagating Characteristics of Pulsed Laser in Rain

    Directory of Open Access Journals (Sweden)

    Jing Guo

    2015-01-01

    Full Text Available To understand the performance of laser ranging system under the rain weather condition, we need to know the propagating characteristics of laser pulse in rain. In this paper, the absorption and attenuation coefficients were calculated based on the scattering theories in discrete stochastic media, and the propagating characteristics of laser pulse in rain were simulated and analyzed using Monte-Carlo method. Some simulation results were verified by experiments, and the simulation results are well matched with the experimental data, with the maximal deviation not less than 7.5%. The results indicated that the propagating laser beam would be attenuated and distorted due to the scattering and absorption of raindrops, and the energy attenuation and pulse shape distortion strongly depended on the laser pulse widths.

  11. Coherent control of stationary light pulses

    Science.gov (United States)

    Zimmer, F. E.; André, A.; Lukin, M. D.; Fleischhauer, M.

    2006-08-01

    We present a detailed analysis of the recently demonstrated technique to generate quasi-stationary pulses of light [M. Bajcsy, A.S. Zibrov, M.D. Lukin, Nature (London) 426 (2003) 638] based on electromagnetically induced transparency. We show that the use of counter-propagating control fields to retrieve a light pulse, previously stored in a collective atomic Raman excitation, leads to quasi-stationary light field that undergoes a slow diffusive spread. The underlying physics of this process is identified as pulse matching of probe and control fields. We then show that spatially modulated control-field amplitudes allow us to coherently manipulate and compress the spatial shape of the stationary light pulse. These techniques can provide valuable tools for quantum nonlinear optics and quantum information processing.

  12. Multi-pulse time delay integration method for flexible 3D super-resolution range-gated imaging.

    Science.gov (United States)

    Xinwei, Wang; Youfu, Li; Yan, Zhou

    2015-03-23

    Constructing flexible regular-shaped range-intensity profiles by the convolution of illuminator laser pulse and sensor gate pulse is crucial for 3D super-resolution range-gated imaging. However, ns-scale rectangular-shaped laser pulse with tunable pulse width is difficult to be obtained, especially for pulsed solid-stated lasers. In this paper we propose a multi-pulse time delay integration (MPTDI) method to reshape range-intensity profiles (RIP) free from the above limitation of pulsed lasers. An equivalent laser pulse temporal shaping model is established to evaluate and optimize the MPTDI method. By using MPTDI, the RIP shape and depth of viewing can both be flexibly changed as desired. Here typical triangular and trapezoidal RIPs are established for 3D imaging under triangular and trapezoidal range-intensity correlation algorithms. In addition, a prototype experiment is demonstrated to prove the feasibility of MPTDI.

  13. Shape-memory polymers

    Directory of Open Access Journals (Sweden)

    Marc Behl

    2007-04-01

    Full Text Available Shape-memory polymers are an emerging class of active polymers that have dual-shape capability. They can change their shape in a predefined way from shape A to shape B when exposed to an appropriate stimulus. While shape B is given by the initial processing step, shape A is determined by applying a process called programming. We review fundamental aspects of the molecular design of suitable polymer architectures, tailored programming and recovery processes, and the quantification of the shape-memory effect. Shape-memory research was initially founded on the thermally induced dual-shape effect. This concept has been extended to other stimuli by either indirect thermal actuation or direct actuation by addressing stimuli-sensitive groups on the molecular level. Finally, polymers are introduced that can be multifunctional. Besides their dual-shape capability, these active materials are biofunctional or biodegradable. Potential applications for such materials as active medical devices are highlighted.

  14. Optimal choice of trapezoidal shaping parameters in digital nuclear spectrometer system

    International Nuclear Information System (INIS)

    Trapezoidal shaping method is widely applied to pulse amplitude extraction in digital nuclear spectrometer system, the optimal selection of the shaping parameters can improve the energy resolution and pulse counting rate. From the view of noise characteristics, ballistic deficit compensation characteristics and pulse pile-up characteristics, in this paper the optimal selection of the trapezoidal shaping parameters is studied on. According to the theoretical analysis and experimental verification, the optimal choice of trapezoidal shaping parameters is similar to the triangle, the rise time is longer and the flat-top width is shorter. (authors)

  15. Tunable optimal compression of ultrabroadband pulses by cross-phase modulation

    NARCIS (Netherlands)

    Spanner, M.; Ivanov, M.Y.; Kalosha, V.; Hermann, J.; Wiersma, D.A.; Pshenichnikov, M.

    2003-01-01

    We show how cross-phase modulation between two pulses, combined with optimal pulse shaping at the input of a dielectric medium; can be used to generate nearly single-cycle Pulses that are tunable from the ultraviolet to the mid-infrared at the output of the medium, precompensating for dispersion to

  16. Complete characterization of a spatiotemporal pulse shaper with two-dimensional Fourier transform spectral interferometry

    Science.gov (United States)

    Amir, W.; Planchon, T. A.; Durfee, C. G.; Squier, J. A.

    2007-04-01

    Spatiotemporal pulse shaping is characterized with two-dimensional Fourier transform spectral interferometry. A deformable-mirror-based bidimensional pulse shaper is used to create simple spatiotemporal structures on a femtosecond pulse, structures that are directly calculated from the measured spatiospectral phases and intensities.

  17. Reinforced Airfoil Shaped Body

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention relates to an airfoil shaped body with a leading edge and a trailing edge extending along the longitudinal extension of the body and defining a profile chord, the airfoil shaped body comprising an airfoil shaped facing that forms the outer surface of the airfoil shaped body...

  18. Ultra-short pulsed laser engineered metal-glass nanocomposites

    CERN Document Server

    Stalmashonak, Andrei; Abdolvand, Amin

    2013-01-01

    Glasses containing metallic nanoparticles exhibit very promising linear and nonlinear optical properties, mainly due to the surface plasmon resonances (SPRs) of the nanoparticles. The spectral position in the visible and near-infrared range and polarization dependence of the SPR are characteristically determined by the nanoparticles’ shapes. The focus of Ultra-Short Pulsed Laser Engineered Metal-Glass Nanocomposites is the interaction of intense ultra-short laser pulses with glass containing silver nanoparticles embedded in soda-lime glass, and nanostructural modifications in metal-glass nanocomposites induced by such laser pulses. In order to provide a comprehensive physical picture of the processes leading to laser-induced persistent shape transformation of the nanoparticles, series of experimental results investigating the dependences of laser assisted shape modifications of nanoparticles with laser pulse intensity, excitation wavelength, temperature are considered. In addition, the resulting local opti...

  19. Shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S.; Bearinger, Jane P.

    2015-06-09

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxyl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  20. An Advantage of the Equivalent Velocity Spectroscopy for Femtsecond Pulse Radiolysis

    CERN Document Server

    Kondoh, Takafumi; Tagawa, Seiichi; Tomosada, Hiroshi; Yang Jin Feng; Yoshida, Yoichi

    2005-01-01

    For studies of electron beam induced ultra-fast reaction process, femtosecond(fs) pulse radiolysis is under construction. To realize fs time resolution, fs electron and analyzing light pulses and their jitter compensation system are needed. About a 100fs electron pulse was generated by a photocathode RF gun linac and a magnetic pulse compressor. Synchronized Ti: Sapphire laser have a puleswidth about 160fs. And, it is significant to avoid degradation of time resolution caused by velocity difference between electron and analyzing light in a sample. In the 'Equivalent velocity spectroscopy' method, incident analyzing light is slant toward electron beam with an angle associated with refractive index of sample. Then, to overlap light wave front and electron pulse shape, electron pulse shape is slanted toward the direction of travel. As a result of the equivalent velocity spectroscopy for hydrated electrons, using slanted electron pulse shape, optical absorption rise time was about 1.4ps faster than normal electro...

  1. Electron Beam Energy Compensation by Controlling RF Pulse Shape

    CERN Document Server

    Kii, T; Kusukame, K; Masuda, K; Nakai, Y; Ohgaki, H; Yamazaki, T; Yoshikawa, K; Zen, H

    2005-01-01

    We have studied on improvement of electron beam macropulse properties from a thermionic RF gun. Though a thermionic RF gun has many salient features, there is a serious problem that back-bombardment effect worsens quality of the beam. To reduce beam energy degradation by this effect, we tried to feed non-flat RF power into the gun. As a result, we successfully obtained about 1.5 times longer macropulse and two times larger total charge per macropulse. On the other hand, we calculated transient evolution of RF power considering non-constant beam loading. The beam loading is evaluated from time evolution of cathode temperature, by use of one dimensional heat conduction model and electron trajectories' calculations by a particle simulation code. Then we found good agreement between the experimental and calculation results. Furthermore, with the same way, we studied the electron beam output dependence on the cathode radius.

  2. Current-pulse generator for electromagnet of induction accelerator

    International Nuclear Information System (INIS)

    A thyristor generator is described that produces in the winding of the electromagnet of a betatron unipolar current pulses of sinusoidal and quasisinusoidal shape with deforcing of the field at the beginning of an acceleration cycle and with a plateau on the pulse top at the end of a cycle. The current amplitude is controlled by a pulse-phase method. The generator is used in apparatus with a pulse duration of 1-10 msec, a maximum electromagnet field energy 45-450 J, a winding voltage of 960-1500 V, and a winding current of 100-500 A for a repetition frequency of 50-200 Hz

  3. Pulse distortion in single-mode fibers. Part 2.

    Science.gov (United States)

    Marcuse, D

    1981-09-01

    The theory of pulse distortion in single-mode fibers is extended to include laser sources such as injection lasers operating simultaneously at several distinct wavelengths. The transmitted pulse is expressed as a Fourier integral whose spectral function is given by an analytical expression in closed form. The rms width of the transmitted pulse is also expressed in closed form. Numerical examples illustrate the influence of the spectral width of the source and of its asymmetry on the shape and rms width of the pulse.

  4. Self-pinching of pulsed laser beams during filamentary propagation

    International Nuclear Information System (INIS)

    Competing nonlinear optical effects that act on femtosecond laser pulses propagating in a self-generated light filament may give rise to a pronounced radial beam deformation, similar to the z-pinch contraction of pulsed high-current discharges. This self-generated spatial beam contraction is accompanied by a pulse break-up that can be beneficially exploited for on-axis temporal compression of the pulse. The pinching mechanism therefore explains the recently observed self-compression and the complicated spatio-temporal shapes typical for filament propagation experiments. (authors)

  5. The effect of object shape and laser beam shape on lidar system resolution

    Science.gov (United States)

    Cheng, Hongchang; Wang, Jingyi; Ke, Jun

    2016-06-01

    In a LIDAR system, a pulsed laser beam is propagated to a scene, and then reflected back by objects. Ideally if the beam diameter and the pulse width are close to zero, then the reflected beam in time domain is similar to a delta function, which can accurately locate an object's position. However, in a practical system, the beam has finite size. Therefore, even if the pulse width is small, an object shape will make the reflected beam stretched along the time axis, then affect system resolution. In this paper, we assume the beam with Gaussian shape. The beam can be formulated as a delta function convolved with a shape function, such as a rectangular function, in time domain. Then the reflected beam can be defined as a system response function convolved with the shape function. We use symmetric objects to analyze the reflected beam. Corn, sphere, and cylinder objects are used to find a LIDAR system's response function. The case for large beam size is discussed. We assume the beam shape is similar to a plane wave. With this assumption, we get the simplified LIDAR system response functions for the three kinds of objects. Then we use tiny spheres to emulate an arbitrary object, and study its effect to the returned beam.

  6. Pulsed electromagnetic field radiation from a narrow slot antenna with a dielectric layer

    OpenAIRE

    Štumpf, M.; De Hoop, A.T.; Lager, I.E.

    2010-01-01

    Analytic time domain expressions are derived for the pulsed electromagnetic field radiated by a narrow slot antenna with a dielectric layer in a two‐dimensional model configuration. In any finite time window of observation, exact pulse shapes for the propagated, reflected, and refracted wave constituents are constructed with the aid of the modified Cagniard method (Cagniard‐DeHoop method). Numerical results are presented for vanishing slot width and field pulse shapes at the dielectric/free s...

  7. Digital Shaping Algorithms for GODDESS

    Science.gov (United States)

    Lonsdale, Sarah-Jane; Cizewski, Jolie; Ratkiewicz, Andrew; Pain, Steven

    2014-09-01

    Gammasphere-ORRUBA: Dual Detectors for Experimental Structure Studies (GODDESS) combines the highly segmented position-sensitive silicon strip detectors of ORRUBA with up to 110 Compton-suppressed HPGe detectors from Gammasphere, for high resolution for particle-gamma coincidence measurements. The signals from the silicon strip detectors have position-dependent rise times, and require different forms of pulse shaping for optimal position and energy resolutions. Traditionally, a compromise was achieved with a single shaping of the signals performed by conventional analog electronics. However, there are benefits to using digital acquisition of the detector signals, including the ability to apply multiple custom shaping algorithms to the same signal, each optimized for position and energy, in addition to providing a flexible triggering system, and a reduction in rate-limitation due to pile-up. Recent developments toward creating digital signal processing algorithms for GODDESS will be discussed. This work is supported in part by the U.S. D.O.E. and N.S.F.

  8. Pulse-Width Jitter Measurement for Laser Diode Pulses

    Institute of Scientific and Technical Information of China (English)

    TANG Jun-Hua; WANG Yun-Cai

    2006-01-01

    @@ Theoretical analysis and experimental measurement of pulse-width jitter of diode laser pulses are presented. The expression of pulse power spectra with all amplitude jitter, timing jitter and pulse-width jitter is deduced.

  9. Drop deformation by laser-pulse impact

    CERN Document Server

    Gelderblom, Hanneke; Klein, Alexander L; Bouwhuis, Wilco; Lohse, Detlef; Villermaux, Emmanuel; Snoeijer, Jacco H

    2015-01-01

    A free-falling absorbing liquid drop hit by a nanosecond laser-pulse experiences a strong recoil-pressure kick. As a consequence, the drop propels forward and deforms into a thin sheet which eventually fragments. We study how the drop deformation depends on the pulse shape and drop properties. We first derive the velocity field inside the drop on the timescale of the pressure pulse, when the drop is still spherical. This yields the kinetic-energy partition inside the drop, which precisely measures the deformation rate with respect to the propulsion rate, before surface tension comes into play. On the timescale where surface tension is important the drop has evolved into a thin sheet. Its expansion dynamics is described with a slender-slope model, which uses the impulsive energy-partition as an initial condition. Completed with boundary integral simulations, this two-stage model explains the entire drop dynamics and its dependance on the pulse shape: for a given propulsion, a tightly focused pulse results in a...

  10. Accurate determination of the absolute phase and temporal-pulse phase of few-cycle laser pulses

    Institute of Scientific and Technical Information of China (English)

    Xia Ke-Yu; Gong Shang-Qing; Niu Yue-Ping; Li Ru-Xin; Xu Zhi-Zhan

    2007-01-01

    A Fourier analysis method is used to accurately determine not only the absolute phase but also the temporalpulse phase of an isolated few-cycle (chirped) laser pulse. This method is independent of the pulse shape and can fully characterize the light wave even though only a few samples per optical cycle are available. It paves the way for investigating the absolute phase-dependent extreme nonlinear optics, and the evolutions of the absolute phase and the temporal-pulse phase of few-cycle laser pulses.

  11. Dynamics of laser-induced electroconvection pulses.

    Science.gov (United States)

    Giebink, N C; Johnson, E R; Saucedo, S R; Miles, E W; Vardanyan, K K; Spiegel, D R; Allen, C C

    2004-06-01

    We first report that, for planar nematic 4-methoxy-benzilidene-4-butylaniline (MBBA), the electroconvection threshold voltage has a nonmonotonic temperature dependence, with a well-defined minimum, and a slope of about -0.12 V/degrees C near room temperature at 70 Hz. Motivated by this observation, we have designed an experiment in which a weak continuous-wave absorbed laser beam with a diameter comparable to the pattern wavelength generates a locally supercritical region, or pulse, in dye-doped MBBA. Working 10-20 % below the laser-free threshold voltage, we observe a steady-state pulse shaped as an ellipse with the semimajor axis oriented parallel to the nematic director, with a typical size of several wavelengths. The pulse is robust, persisting even when spatially extended rolls develop in the surrounding region, and displays rolls that counterpropagate along the director at frequencies of tenths of Hz, with the rolls on the left (right) side of the ellipse moving to the right (left). Systematic measurements of the sample-voltage dependence of the pulse amplitude, spatial extent, and frequency show a saturation or decrease when the control parameter (evaluated at the center of the pulse) approaches approximately 0.3. We propose that the model for these pulses should be based on the theory of control-parameter ramps, supplemented with new terms to account for the advection of heat away from the pulse when the surrounding state becomes linearly unstable. The advection creates a negative feedback between the pulse size and the efficiency of heat transport, which we argue is responsible for the attenuation of the pulse at larger control-parameter values.

  12. Dynamics of laser-induced electroconvection pulses

    Science.gov (United States)

    Giebink, N. C.; Johnson, E. R.; Saucedo, S. R.; Miles, E. W.; Vardanyan, K. K.; Spiegel, D. R.; Allen, C. C.

    2004-06-01

    We first report that, for planar nematic 4-methoxy-benzilidene-4-butylaniline (MBBA), the electroconvection threshold voltage has a nonmonotonic temperature dependence, with a well-defined minimum, and a slope of about -0.12 V/° C near room temperature at 70 Hz. Motivated by this observation, we have designed an experiment in which a weak continuous-wave absorbed laser beam with a diameter comparable to the pattern wavelength generates a locally supercritical region, or pulse, in dye-doped MBBA. Working 10 20 % below the laser-free threshold voltage, we observe a steady-state pulse shaped as an ellipse with the semimajor axis oriented parallel to the nematic director, with a typical size of several wavelengths. The pulse is robust, persisting even when spatially extended rolls develop in the surrounding region, and displays rolls that counterpropagate along the director at frequencies of tenths of Hz, with the rolls on the left () side of the ellipse moving to the right (left). Systematic measurements of the sample-voltage dependence of the pulse amplitude, spatial extent, and frequency show a saturation or decrease when the control parameter (evaluated at the center of the pulse) approaches ˜0.3 . We propose that the model for these pulses should be based on the theory of control-parameter ramps, supplemented with new terms to account for the advection of heat away from the pulse when the surrounding state becomes linearly unstable. The advection creates a negative feedback between the pulse size and the efficiency of heat transport, which we argue is responsible for the attenuation of the pulse at larger control-parameter values.

  13. Measurement of Ultra-Short Single-Photon Pulse Duration with Two-Photon Interference

    Institute of Scientific and Technical Information of China (English)

    LV Fan; SUN Fang-Wen; ZOU Chang-Ling; HAN Zheng-Fu; GUO Guang-Can

    2011-01-01

    We proposed a protocol of measuring the duration of ultra-short single-photon pulse with two-photon interference.The pulse duration can be obtained from the width of the visibility of two-photon Hong-Ou-Mandel interference or the indistinguishability of the two photons. Moreover, the shape of a single-photon pulse can be measured with ultra-short single-photon pulses through the two-photon interference.%@@ We proposed a protocol of measuring the duration of ultra-short single-photon pulse with two-photon interference.The pulse duration can be obtained from the width of the visibility of two-photon Hong-Ou-Mandel interference or the indistinguishability of the two photons.Moreover, the shape of a single-photon pulse can be measured with ultra-short single-photon pulses through the two-photon interference.

  14. Parabolic similariton Yb-fiber laser with triangular pulse evolution

    Science.gov (United States)

    Wang, Sijia; Wang, Lei

    2016-04-01

    We propose a novel mode-locked fiber laser design which features a passive nonlinear triangular pulse formation and self-similar parabolic pulse amplification intra cavity. Attribute to the nonlinear reshaping progress in the passive fiber, a triangular-profiled pulse with negative-chirp is generated and paved the way for rapid and efficient self-similar parabolic evolution in a following short-length high-gain fiber. In the meanwhile, the accompanied significantly compressed narrow spectrum from this passive nonlinear reshaping also gives the promise of pulse stabilization and gain-shaping robustness without strong filtering. The resulting short average intra-cavity pulse duration, low amplified spontaneous emission (ASE) and low intra-cavity power loss are essential for the low-noise operation. Simulations predict this modelocked fiber laser allows for high-energy ultra-short transform-limited pulse generation exceeding the gain bandwidth. The output pulse has a de-chirped duration (full-width at half maximum, FWHM) of 27 fs. In addition to the ultrafast laser applications, the proposed fiber laser scheme can support low-noise parabolic and triangular pulse trains at the same time, which are also attractive in optical pulse shaping, all-optical signal processing and high-speed communication applications.

  15. Hybrid chirped pulse amplification system

    Science.gov (United States)

    Barty, Christopher P.; Jovanovic, Igor

    2005-03-29

    A hybrid chirped pulse amplification system wherein a short-pulse oscillator generates an oscillator pulse. The oscillator pulse is stretched to produce a stretched oscillator seed pulse. A pump laser generates a pump laser pulse. The stretched oscillator seed pulse and the pump laser pulse are directed into an optical parametric amplifier producing an optical parametric amplifier output amplified signal pulse and an optical parametric amplifier output unconverted pump pulse. The optical parametric amplifier output amplified signal pulse and the optical parametric amplifier output laser pulse are directed into a laser amplifier producing a laser amplifier output pulse. The laser amplifier output pulse is compressed to produce a recompressed hybrid chirped pulse amplification pulse.

  16. Discriminative Shape Alignment

    DEFF Research Database (Denmark)

    Loog, M.; de Bruijne, M.

    2009-01-01

    The alignment of shape data to a common mean before its subsequent processing is an ubiquitous step within the area shape analysis. Current approaches to shape analysis or, as more specifically considered in this work, shape classification perform the alignment in a fully unsupervised way......, not taking into account that eventually the shapes are to be assigned to two or more different classes. This work introduces a discriminative variation to well-known Procrustes alignment and demonstrates its benefit over this classical method in shape classification tasks. The focus is on two...

  17. Detection of Crab Giant Pulses Using the Mileura Widefield Array Low Frequency Demonstrator Field Prototype System

    OpenAIRE

    Bhat, N. D. Ramesh; Wayth, Randall B.; Knight, Haydon S.; Bowman, Judd D.; Oberoi, Divya; Barnes, David G.; Briggs, Frank H.; Cappallo, Roger J.; Herne, David; Kocz, Jonathon; Lonsdale, Colin J.; Lynch, Mervyn J.; Stansby, Bruce; Stevens, Jamie; Torr, Glen

    2007-01-01

    We report on the detection of giant pulses from the Crab Nebula pulsar at a frequency of 200 MHz using the field deployment system designed for the Mileura Widefield Array's Low Frequency Demonstrator (MWA-LFD). Our observations are among the first high-quality detections at such low frequencies. The measured pulse shapes are deconvolved for interstellar pulse broadening, yielding a pulse-broadening time of 670$\\pm$100 $\\mu$s, and the implied strength of scattering (scattering measure) is the...

  18. Pulse Self-trapping Robustness to Polarization Mode Dispersion in Optical Fiber

    Institute of Scientific and Technical Information of China (English)

    CHEN Weicheng; XU Wencheng; LUO Aiping; CUI Hu; CHEN Yongzhu; LIU Songhao

    2002-01-01

    In this paper, pulse self-trapping robustness to polarization mode dispersion in optical fibers is studied. Nonlinear pulse can be used to suppress PMD despite the input pulse shapes is found. When the nonlinear effect is stronger (initial pulse amplitude is larger), the suppression degree to PMD is better. As the initial chirp is considered, we find that the chirp is harmful to suppress PMD. The more is initial chirp, the more is the PMD value.

  19. Pulse Pressure in Clinical Practice

    Directory of Open Access Journals (Sweden)

    Jiri Parenica

    2012-02-01

    Full Text Available The review presents basic information about the pulse pressure. The variables related to pulse pressure are briefly explained - arterial stiffness, arterial compliance, pulse wave velocity, pulse pressure amplification and augmentation index. We present some recent trials and observational studies that show the importance of pulse pressure in clinical practice. Briefly the possibilities of influencing the pulse pressure are discussed.

  20. Pulse profile stability of the Crab pulsar

    Institute of Scientific and Technical Information of China (English)

    Chetana Jain; Biswajit Paul

    2011-01-01

    We present an X-ray timing analysis of the Crab pulsar,PSR B0531+21,using archival RXTE data.We have investigated the stability of the Crab pulse profile,in soft (2-20keV) and hard (30-100keV) X-ray energies,over the last decade of RXTE operation.The analysis includes measurement of the separation between the two pulse peaks and the intensity and widths of the two peaks.We did not find any significant time dependency in the pulse shape.The two peaks have been stable in phase,intensity and width for the last ten years.The first pulse is relatively stronger at soft X-rays.The first pulse peak is narrower than the second peak in both soft and hard X-ray energies.Both the peaks show a slow rise and a steeper fall.The ratio of the pulsed photons in the two peaks is also constant in time.