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Sample records for pass beam phase

  1. Single beam pass migmacell method and apparatus

    International Nuclear Information System (INIS)

    Maglich, B.C.; Nering, J.E.; Mazarakis, M.G.; Miller, R.A.

    1976-01-01

    The invention provides improvements in migmacell apparatus and method by dispensing with the need for metastable confinement of injected molecular ions for multiple precession periods. Injected molecular ions undergo a 'single pass' through the reaction volume. By preconditioning the injected beam such that it contains a population distribution of molecules in higher vibrational states than in the case of a normal distribution, injected molecules in the single pass exper-ience collisionless dissociation in the migmacell under magnetic influence, i.e., so-called Lorentz dissociation. Dissociationions then form atomic migma

  2. The effect of thermal de-phasing on the beam quality of a high-power single-pass second harmonic generation

    Science.gov (United States)

    Sadat Hashemi, Somayeh; Ghavami Sabouri, Saeed; Khorsandi, Alireza

    2018-04-01

    We present a theoretical model in order to study the effect of a thermally loaded crystal on the quality of a second-harmonic (SH) beam generated in a high-power pumping regime. The model is provided based on using a particular structure of oven considered for MgO:PPsLT nonlinear crystal to compensate for the thermal de-phasing effect that as the pumping power reaches up to 50 W degrades the conversion efficiency and beam quality of the interacting beams. Hereupon, the quality of fundamental beam is involved in the modeling to investigate the final effect on the beam quality of generated SH beam. Beam quality evaluation is subsequently simulated using Hermite-Gaussian modal decomposition approach for a range of fundamental beam qualities varied from 1 to 3 and for different levels of input powers. To provide a meaningful comparison numerical simulation is correlated with real data deduced from a high-power SH generation (SHG) experimental device. It is found that when using the open-top oven scheme and fixing the fundamental M 2-factor at nearly 1, for a range of input powers changing from 15 to 30 W, the M 2-factor of SHG beam is degraded from 9% to 24%, respectively, confirming very good consistency with the reported experimental results.

  3. Regenerative beam breakup in multi-pass electron accelerators

    International Nuclear Information System (INIS)

    Vetter, A.M. Jr.

    1980-01-01

    Important electron coincidence experiments in the 1 to 2 GeV range require electron beams of high intensity and high duty factor. To provide such beams, multi-pass electron accelerator systems are being developed at many laboratories. The beam current in multi-pass electron machines is limited by bean breakup which arises from interaction of the electron beam with deflection modes of the accelerator structure. Achieving high beam intensity (50 to 100 μA) will require detailed understanding and careful control of beam breakup phenomena, and is the subject of this thesis. The TM 11 -like traveling wave theory is applied to obtain a physical understanding of beam-mode interactions and the principles of focussing in simple two-pass systems, and is used as a basis for general studies of the dependence of starting current on accelerator parameters in systems of many passes. The concepts developed are applied in analyzing beam breakup in the superconducting recyclotron at Stanford. Measurements of beam interactions with selected breakup modes are incorporated in a simple model in order to estimate relative strengths of breakup modes and to predict starting currents in five-pass operation. The improvement over these predicted currents required in order to obtain 50 to 100 μA beams is shown to be achievable with a combination of increased breakup mode loading and improved beam optics

  4. The Single Pass RF Driver: Final beam compression

    Energy Technology Data Exchange (ETDEWEB)

    Burke, Robert, E-mail: rjburke@fusionpowercorporation.com

    2014-01-01

    The Single Pass RF Driver (SPRFD) compacts the beam from the linac without storage rings by manipulations that take advantage of the multiplicity of isotopes (16), the preserved µbunch structure, and increased total linac current. Magnetic switches on a first set of delay lines rearrange the internal structure of the various isotopic beams. A second set of delay lines sets the relative timing of the 16 isotopic beam sections so they will telescope at the pellet, in one of multiple fusion chambers, e.g. 10. Shortening each isotopic beam section uses preservation of the µbunch structure up to the final ∼2 km drift before final focus. Just before the final drift, differential acceleration of the µbunches in each isotopic beam section (128 total) launches an axial collapse, referred to as the “Slick”. The µbunches interpenetrate as their centers of mass move toward each other and individual µbunches lengthen due to their momentum spread. In longitudinal phase space they slide over one another as they lengthen in time and slim down in instantaneous energy spread. The permissible amount of µbunch lengthening is set by the design pulse shape at the pellet, which varies for different groups of isotopes. In narrow bands of ranges according to the role for each isotope group in the pellet, the ranges extend from 1 to 10 g/cm{sup 2} to drive the cylinder barrel and thin hemispherical end caps, to heat the ∼0.5 g/cm{sup 2}ρR fast ignition zone, and to improve the quasi-sphericity of the compression of the fast ignition zones at the pellet's ends. Because the µbunch–µbunch momentum differences are correlated, time-ramped beamline transport elements close after the differential accelerator are used to correct the associated shifts of focal point. Beam neutralization is needed after the differential acceleration until adjacent bunches begin to overlap. Concurrent collapse of each isotope and telescoping of the 16 isotopes cause the current in each beamline

  5. The Single Pass RF Driver: Final beam compression

    International Nuclear Information System (INIS)

    Burke, Robert

    2014-01-01

    The Single Pass RF Driver (SPRFD) compacts the beam from the linac without storage rings by manipulations that take advantage of the multiplicity of isotopes (16), the preserved µbunch structure, and increased total linac current. Magnetic switches on a first set of delay lines rearrange the internal structure of the various isotopic beams. A second set of delay lines sets the relative timing of the 16 isotopic beam sections so they will telescope at the pellet, in one of multiple fusion chambers, e.g. 10. Shortening each isotopic beam section uses preservation of the µbunch structure up to the final ∼2 km drift before final focus. Just before the final drift, differential acceleration of the µbunches in each isotopic beam section (128 total) launches an axial collapse, referred to as the “Slick”. The µbunches interpenetrate as their centers of mass move toward each other and individual µbunches lengthen due to their momentum spread. In longitudinal phase space they slide over one another as they lengthen in time and slim down in instantaneous energy spread. The permissible amount of µbunch lengthening is set by the design pulse shape at the pellet, which varies for different groups of isotopes. In narrow bands of ranges according to the role for each isotope group in the pellet, the ranges extend from 1 to 10 g/cm 2 to drive the cylinder barrel and thin hemispherical end caps, to heat the ∼0.5 g/cm 2 ρR fast ignition zone, and to improve the quasi-sphericity of the compression of the fast ignition zones at the pellet's ends. Because the µbunch–µbunch momentum differences are correlated, time-ramped beamline transport elements close after the differential accelerator are used to correct the associated shifts of focal point. Beam neutralization is needed after the differential acceleration until adjacent bunches begin to overlap. Concurrent collapse of each isotope and telescoping of the 16 isotopes cause the current in each beamline to rise

  6. Beam dynamics simulation of a double pass proton linear accelerator

    Directory of Open Access Journals (Sweden)

    Kilean Hwang

    2017-04-01

    Full Text Available A recirculating superconducting linear accelerator with the advantage of both straight and circular accelerator has been demonstrated with relativistic electron beams. The acceleration concept of a recirculating proton beam was recently proposed [J. Qiang, Nucl. Instrum. Methods Phys. Res., Sect. A 795, 77 (2015NIMAER0168-900210.1016/j.nima.2015.05.056] and is currently under study. In order to further support the concept, the beam dynamics study on a recirculating proton linear accelerator has to be carried out. In this paper, we study the feasibility of a two-pass recirculating proton linear accelerator through the direct numerical beam dynamics design optimization and the start-to-end simulation. This study shows that the two-pass simultaneous focusing without particle losses is attainable including fully 3D space-charge effects through the entire accelerator system.

  7. Single Pass Stripline Beam Position Monitor Design, Fabrication and Commissioning

    Directory of Open Access Journals (Sweden)

    McKinlay J.

    2012-10-01

    Full Text Available To monitor the position of the electron beam during transport from the Booster Synchrotron to the Storage Ring at the Australian Synchrotron, a stripline Beam Position Monitor (BPM has been designed, fabricated and installed in-house. The design was based on an existing stripline in the Booster and modified for the transfer line with a particular emphasis on ensuring the line impedance is properly matched to the detector system. The initial bench tests of a prototype stripline showed that the fabrication of the four individual striplines in the BPM was made precisely, each with a measured standing wave ratio (SWR of 1.8 at 500 MHz. Further optimization for impedance matching will be done for new stripline BPMs. The linearity and gain factor was measured with the detector system. The detector system that digitizes the signals is an Instrumentation Technologies Brilliance Single Pass [1]. The results show an error of 1 mm at an offset (from the electrical centre of 10 mm when a linear gain factor is assumed and an RMS noise of ~150 um that decreases to < 10 um with increasing signal intensity. The results were under our requirements for the transport line. The commissioning results of the stripline will also be presented showing a strong signal for an electron beam with an estimated integrated charge of ~50 nC with a position stability of 28 um (horizontal and 75 um (vertical.

  8. Single Pass Stripline Beam Position Monitor Design, Fabrication and Commissioning

    Science.gov (United States)

    Tan, Y.-R. E.; Wang, D.; Van Garderen, E.; McKinlay, J.

    2012-10-01

    To monitor the position of the electron beam during transport from the Booster Synchrotron to the Storage Ring at the Australian Synchrotron, a stripline Beam Position Monitor (BPM) has been designed, fabricated and installed in-house. The design was based on an existing stripline in the Booster and modified for the transfer line with a particular emphasis on ensuring the line impedance is properly matched to the detector system. The initial bench tests of a prototype stripline showed that the fabrication of the four individual striplines in the BPM was made precisely, each with a measured standing wave ratio (SWR) of 1.8 at 500 MHz. Further optimization for impedance matching will be done for new stripline BPMs. The linearity and gain factor was measured with the detector system. The detector system that digitizes the signals is an Instrumentation Technologies Brilliance Single Pass [1]. The results show an error of 1 mm at an offset (from the electrical centre) of 10 mm when a linear gain factor is assumed and an RMS noise of ~150 um that decreases to < 10 um with increasing signal intensity. The results were under our requirements for the transport line. The commissioning results of the stripline will also be presented showing a strong signal for an electron beam with an estimated integrated charge of ~50 nC with a position stability of 28 um (horizontal) and 75 um (vertical).

  9. Beam Phase Detection for Proton Therapy Accelerators

    CERN Document Server

    Aminov, Bachtior; Getta, Markus; Kolesov, Sergej; Pupeter, Nico; Stephani, Thomas; Timmer, J

    2005-01-01

    The industrial application of proton cyclotrons for medical applications has become one of the important contributions of accelerator physics during the last years. This paper describes an advanced vector demodulating technique used for non-destructive measurements of beam intensity and beam phase over 360°. A computer controlled I/Q-based phase detector with a very large dynamic range of 70 dB permits the monitoring of beam intensity, phase and eventually energy for wide range of beam currents down to -130 dBm. In order to avoid interference from the fundamental cyclotron frequency the phase detection is performed at the second harmonic frequency. A digital low pass filter with adjustable bandwidth and steepness is implemented to improve accuracy. With a sensitivity of the capacitive pickup in the beam line of 30 nV per nA of proton beam current at 250 MeV, accurate phase and intensity measurements can be performed with beam currents down to 3.3 nA.

  10. CLIC Drive Beam Phase Stabilisation

    CERN Document Server

    Gerbershagen, Alexander; Schulte, Daniel

    The thesis presents phase stability studies for the Compact Linear Collider (CLIC) and focuses in particular on CLIC Drive Beam longitudinal phase stabilisation. This topic constitutes one of the main feasibility challenges for CLIC construction and is an essential component of the current CLIC stabilisation campaign. The studies are divided into two large interrelated sections: the simulation studies for the CLIC Drive Beam stability, and measurements, data analysis and simulations of the CLIC Test Facility (CTF3) Drive Beam phase errors. A dedicated software tool has been developed for a step-by-step analysis of the error propagation through the CLIC Drive Beam. It uses realistic RF potential and beam loading amplitude functions for the Drive and Main Beam accelerating structures, complete models of the recombination scheme and compressor chicane as well as of further CLIC Drive Beam modules. The tool has been tested extensively and its functionality has been verified. The phase error propagation at CLIC h...

  11. Pulse propagation in a two-pass optical amplifier with arbitrary laser beams overlap

    Directory of Open Access Journals (Sweden)

    AH Farahbod

    2011-09-01

    Full Text Available An analytical model for two-pass optical amplifier with arbitrary beams overlap has been developed which generalized the classical theory of Frantz-Nodvik for single pass amplifier. The effect of counterpropagating beams on gain and output energy fluence included in the model. Moreover, the appropriate limiting relations for two special cases of weak input signal and saturation state of the amplifier gain have been derived. The results indicate that for complete beams overlap, the gain and output energy have the least values. The model predictions are consistent with experimental observations and exact analytical model for two-pass amplifier when beam propagation paths are coincided.

  12. Beam phase space and emittance

    International Nuclear Information System (INIS)

    Buon, J.

    1990-12-01

    The classical and elementary results for canonical phase space, the Liouville theorem and the beam emittance are reviewed. Then, the importance of phase portraits to obtain a geometrical description of motion is emphasized, with examples in accelerator physics. Finally, a statistical point of view is used to define beam emittance, to study its law of approximate conservation and to treat two particular examples

  13. Phase measurement and control of pulsed charged beams

    International Nuclear Information System (INIS)

    Lewis, R.N.

    1978-01-01

    A method and system is described that measures and controls the arrival phase of a pulsed ion beam. The repetitive beam pulse passes through and resonantly excites a high-Q structure, tuned to the beam repetition frequency or to a higher harmonic thereof. A reference signal of the same frequency is phase-flipped from -90 0 to +90 0 at a high audio rate and also coupled to the resonator. The low-level output signal, comprised of the vector sum of the beam-induced signal and the phase-flipped reference, is amplified and processed to obtain phase information. The system is usable for beams with average currents as low as a few picoamperes and can be used in the measurement and control of pulsed beam experiments involving timing, the control of beam phase for rf particle accelerators and the nondestructive measurement of beam energy. (Auth.)

  14. Green light for neutrino beam to pass below the Alps

    CERN Multimedia

    Abbott, A

    1999-01-01

    CERN council have approved a plan to send a beam of muon neutrinos under the Alps from Geneva to the Gran Sasso laboratories near Rome. INFN is organising two experiments - OPERA and ICANOE, to study the neutrino oscillations as they travel (1/2 pg)

  15. A calculation technique of passing of a powerful relativistic beam through substance

    International Nuclear Information System (INIS)

    Pobitko, A.I.; Sal'nikov, L.I.; Sukhovitskij, E.Sh.

    1995-01-01

    The calculation algorithm of passing powerful relativistic beam through substance is developed. Algorithm of calculation is separated on the following problems: 1) a trial charge movement in electromagnetic field of the cylindrical geometry; 2) a computing of own electromagnetic field arising at movement of a particle heavy-current beam in a target; 3) accounting of an interaction of a beam with target atoms; 4) accounting of change of the target properties in a time; 5) geometry and construction of an iterative procedure of calculation. The calculation of passing heavy-current beams of charged particles for transient case is carried out by Monte Carlo method. A conclusion of equations of movement trial charge and technique of calculation own electromagnetic field of the powerful relativistic beam at passing through substance are resulted. 6 refs

  16. Beam phase space and emittance

    International Nuclear Information System (INIS)

    Buon, J.

    1992-02-01

    The classical and elementary results for canonical phase space, the Liouville theorem and the beam emittance are reviewed. Then, the importance of phase portraits to obtain a geometrical description of motion is emphasized, with examples in accelerator physics. Finally, a statistical point of view is used to define beam emittance, to study its law of approximate conservation, with three particular examples, and to introduce a beam envelope-ellipse and the β-function, emphasing the statistical features of its properties. (author) 14 refs.; 11 figs

  17. Formation of temperature fields in doped anisotropic crystals under spatially inhomogeneous light beams passing through them

    Energy Technology Data Exchange (ETDEWEB)

    Zaitseva, E. V.; Markelov, A. S.; Trushin, V. N., E-mail: trushin@phys.unn.ru; Chuprunov, E. V. [Nizhni Novgorod State University (Russian Federation)

    2013-12-15

    The features of formation of thermal fields in potassium dihydrophosphate crystal doped with potassium permanganate under a 532-nm laser beam passing through it have been investigated. Data on the influence of birefringence on the temperature distribution in an anisotropic crystal whose surface is illuminated by a spatially modulated light beam are presented.

  18. rf beam-current, -phase, and -position monitors

    International Nuclear Information System (INIS)

    Young, L.

    1984-01-01

    A prototype rf beam monitor has been tested on the Racetrack Microtron's (RTM) 100 kV injector beam line at the National Bureau of Standards (NBS). This beam monitor is capable of measuring the current, the relative phase, and the position of the beam. The beam is bunched at 2380 MHz for acceleration by the linac in the injector beam line. This train of beam bunches passing through the beam monitor cavities excites the cavities at this resonance frequency of 2380 MHz. Probes in the cavities couple some of the beam-excited rf power out of the cavities. This rf power can be amplified if necessary and then analyzed by a double balanced mixer (DBM). The DBM can also be used as a phase detector. The effective shunt impedance of the cavities was measured with the CW beam. For the position monitor cavity, the shunt impedance is proportional to the displacement from the axis. The measured response of the prototype rf beam current monitor setup is a linear function of beam current. Response of the rf beam-position monitor is also shown

  19. Per-beam, planar IMRT QA passing rates do not predict clinically relevant patient dose errors

    Energy Technology Data Exchange (ETDEWEB)

    Nelms, Benjamin E.; Zhen Heming; Tome, Wolfgang A. [Canis Lupus LLC and Department of Human Oncology, University of Wisconsin, Merrimac, Wisconsin 53561 (United States); Department of Medical Physics, University of Wisconsin, Madison, Wisconsin 53705 (United States); Departments of Human Oncology, Medical Physics, and Biomedical Engineering, University of Wisconsin, Madison, Wisconsin 53792 (United States)

    2011-02-15

    Purpose: The purpose of this work is to determine the statistical correlation between per-beam, planar IMRT QA passing rates and several clinically relevant, anatomy-based dose errors for per-patient IMRT QA. The intent is to assess the predictive power of a common conventional IMRT QA performance metric, the Gamma passing rate per beam. Methods: Ninety-six unique data sets were created by inducing four types of dose errors in 24 clinical head and neck IMRT plans, each planned with 6 MV Varian 120-leaf MLC linear accelerators using a commercial treatment planning system and step-and-shoot delivery. The error-free beams/plans were used as ''simulated measurements'' (for generating the IMRT QA dose planes and the anatomy dose metrics) to compare to the corresponding data calculated by the error-induced plans. The degree of the induced errors was tuned to mimic IMRT QA passing rates that are commonly achieved using conventional methods. Results: Analysis of clinical metrics (parotid mean doses, spinal cord max and D1cc, CTV D95, and larynx mean) vs IMRT QA Gamma analysis (3%/3 mm, 2/2, 1/1) showed that in all cases, there were only weak to moderate correlations (range of Pearson's r-values: -0.295 to 0.653). Moreover, the moderate correlations actually had positive Pearson's r-values (i.e., clinically relevant metric differences increased with increasing IMRT QA passing rate), indicating that some of the largest anatomy-based dose differences occurred in the cases of high IMRT QA passing rates, which may be called ''false negatives.'' The results also show numerous instances of false positives or cases where low IMRT QA passing rates do not imply large errors in anatomy dose metrics. In none of the cases was there correlation consistent with high predictive power of planar IMRT passing rates, i.e., in none of the cases did high IMRT QA Gamma passing rates predict low errors in anatomy dose metrics or vice versa

  20. Per-beam, planar IMRT QA passing rates do not predict clinically relevant patient dose errors

    International Nuclear Information System (INIS)

    Nelms, Benjamin E.; Zhen Heming; Tome, Wolfgang A.

    2011-01-01

    Purpose: The purpose of this work is to determine the statistical correlation between per-beam, planar IMRT QA passing rates and several clinically relevant, anatomy-based dose errors for per-patient IMRT QA. The intent is to assess the predictive power of a common conventional IMRT QA performance metric, the Gamma passing rate per beam. Methods: Ninety-six unique data sets were created by inducing four types of dose errors in 24 clinical head and neck IMRT plans, each planned with 6 MV Varian 120-leaf MLC linear accelerators using a commercial treatment planning system and step-and-shoot delivery. The error-free beams/plans were used as ''simulated measurements'' (for generating the IMRT QA dose planes and the anatomy dose metrics) to compare to the corresponding data calculated by the error-induced plans. The degree of the induced errors was tuned to mimic IMRT QA passing rates that are commonly achieved using conventional methods. Results: Analysis of clinical metrics (parotid mean doses, spinal cord max and D1cc, CTV D95, and larynx mean) vs IMRT QA Gamma analysis (3%/3 mm, 2/2, 1/1) showed that in all cases, there were only weak to moderate correlations (range of Pearson's r-values: -0.295 to 0.653). Moreover, the moderate correlations actually had positive Pearson's r-values (i.e., clinically relevant metric differences increased with increasing IMRT QA passing rate), indicating that some of the largest anatomy-based dose differences occurred in the cases of high IMRT QA passing rates, which may be called ''false negatives.'' The results also show numerous instances of false positives or cases where low IMRT QA passing rates do not imply large errors in anatomy dose metrics. In none of the cases was there correlation consistent with high predictive power of planar IMRT passing rates, i.e., in none of the cases did high IMRT QA Gamma passing rates predict low errors in anatomy dose metrics or vice versa. Conclusions: There is a lack of correlation between

  1. Beam tuning and stabilization using beam phase measurements at GANIL

    International Nuclear Information System (INIS)

    Chabert, A.; Loyer, F.; Sauret, J.

    1984-06-01

    Owing to the great sensitivity of the beam phase to the various parameters, on line beam phase measurements proved to be a very efficient way of tuning and stabilizing the beam of the multi-accelerator complex. We recall the system which allows to obtain the different kinds of accurate measurements we need and describe the main applications: - tuning process (buncher and SSC's RF phase determination, setting of the required radial beam phase law in the SSC's); - stabilization of the beam by loops, the basic principle of which being to keep constant the beam central phase all along the machine by adjusting RF voltages or magnetic fields. Feedback loops are described and comparative results with and without feedback are given

  2. Modeling beams with elements in phase space

    International Nuclear Information System (INIS)

    Nelson, E.M.

    1998-01-01

    Conventional particle codes represent beams as a collection of macroparticles. An alternative is to represent the beam as a collection of current carrying elements in phase space. While such a representation has limitations, it may be less noisy than a macroparticle model, and it may provide insights about the transport of space charge dominated beams which would otherwise be difficult to gain from macroparticle simulations. The phase space element model of a beam is described, and progress toward an implementation and difficulties with this implementation are discussed. A simulation of an axisymmetric beam using 1d elements in phase space is demonstrated

  3. Phase measurement and control of bunched beams

    International Nuclear Information System (INIS)

    Lewis, R.N.

    1978-01-01

    An ion bean buncher was developed at ANL for bunching all ion species through a tandem accelerator. Transit time variations through the tandem, caused by ripple and fluctuations in the injection and lens power supplies and terminal voltage, and to varying voltage distributions in the accelerating tube, cause a beam-phase variation at the output of the tandem. A beam-phase measurement and control system was designed and installed in conjunction with the ion beam buncher to control beam phase at the tandem output. That system is described

  4. The study of the structural stability of the spiral laser beams propagation through inhomogeneous phase medium

    Science.gov (United States)

    Zinchik, Alexander A.; Muzychenko, Yana B.

    2015-06-01

    This paper discusses theoretical and experimental results of the investigation of light beams that retain their intensity structure during propagation and focusing. Spiral laser beams are a family of laser beams that preserve the structural stability up to scale and rotation with the propagation. Properties of spiral beams are of practical interest for laser technology, medicine and biotechnology. Researchers use a spiral beams for movement and manipulation of microparticles. Functionality laser manipulators can be significantly enhanced by using spiral beams whose intensity remains invariable. It is well known, that these beams has non-zero orbital angular momentum. Spiral beams have a complicated phase distribution in cross section. In this paper we investigate the structural stability of the laser beams having a spiral phase structure by passing them through an inhomogeneous phase medium. Laser beam is passed through a medium is characterized by a random distribution of phase in the range 0..2π. The modeling was performed using VirtualLab 5.0 (manufacturer LightTrans GmbH). Compared the intensity distribution of the spiral and ordinary laser beam after the passage of the inhomogeneous medium. It is shown that the spiral beams exhibit a significantly better structural stability during the passage phase heterogeneous environments than conventional laser beams. The results obtained in the simulation are tested experimentally. Experimental results show good agreement with the theoretical results.

  5. Electron Beam Welding of IN792 DS: Effects of Pass Speed and PWHT on Microstructure and Hardness.

    Science.gov (United States)

    Angella, Giuliano; Barbieri, Giuseppe; Donnini, Riccardo; Montanari, Roberto; Richetta, Maria; Varone, Alessandra

    2017-09-05

    Electron Beam (EB) welding has been used to realize seams on 2 mm-thick plates of directionally solidified (DS) IN792 superalloy. The first part of this work evidenced the importance of pre-heating the workpiece to avoid the formation of long cracks in the seam. The comparison of different pre-heating temperatures (PHT) and pass speeds ( v ) allowed the identification of optimal process parameters, namely PHT = 300 °C and v = 2.5 m/min. The microstructural features of the melted zone (MZ); the heat affected zone (HAZ), and base material (BM) were investigated by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), electron back-scattered diffraction (EBSD), X-ray diffraction (XRD), and micro-hardness tests. In the as-welded condition; the structure of directionally oriented grains was completely lost in MZ. The γ' phase in MZ consisted of small (20-40 nm) round shaped particles and its total amount depended on both PHT and welding pass speed, whereas in HAZ, it was the same BM. Even if the amount of γ' phase in MZ was lower than that of the as-received material, the nanometric size of the particles induced an increase in hardness. EDS examinations did not show relevant composition changes in the γ' and γ phases. Post-welding heat treatments (PWHT) at 700 and 750 °C for two hours were performed on the best samples. After PWHTs, the amount of the ordered phase increased, and the effect was more pronounced at 750 °C, while the size of γ' particles in MZ remained almost the same. The hardness profiles measured across the joints showed an upward shift, but peak-valley height was a little lower, indicating more homogeneous features in the different zones.

  6. Wakefields generated by electron beams passing through a waveguide loaded with a slightly dispersive active medium

    Directory of Open Access Journals (Sweden)

    Andrey V. Tyukhtin

    2007-05-01

    Full Text Available The wakefields of a relativistic electron beam passing through a waveguide loaded with an active medium with weak resonant dispersion are considered. For the calculations in this paper, the parameters of the medium are those of a solution of fullerene (C_{60} in a nematic liquid crystal that exhibits activity in the X-band. It is shown that several of the TM accelerating modes can be amplified for the geometries under consideration; structures in which higher order modes are amplified exhibit essential advantages as PASERs. In particular, the amplification of the highest mode occurs in a structure loaded with a rather thick active medium layer that maximizes the energy stored by the active medium.

  7. Nonlinear transport of accelerator beam phase space

    International Nuclear Information System (INIS)

    Xie Xi; Xia Jiawen

    1995-01-01

    Based on the any order analytical solution of accelerator beam dynamics, the general theory for nonlinear transport of accelerator beam phase space is developed by inverse transformation method. The method is general by itself, and hence can also be applied to the nonlinear transport of various dynamic systems in physics, chemistry and biology

  8. Wave-optics simulation of the double-pass beam propagation in modulating retro-reflector FSO systems using a corner cube reflector.

    Science.gov (United States)

    Yang, Guowei; You, Shengzui; Bi, Meihua; Fan, Bing; Lu, Yang; Zhou, Xuefang; Li, Jing; Geng, Hujun; Wang, Tianshu

    2017-09-10

    Free-space optical (FSO) communication utilizing a modulating retro-reflector (MRR) is an innovative way to convey information between the traditional optical transceiver and the semi-passive MRR unit that reflects optical signals. The reflected signals experience turbulence-induced fading in the double-pass channel, which is very different from that in the traditional single-pass FSO channel. In this paper, we consider the corner cube reflector (CCR) as the retro-reflective device in the MRR. A general geometrical model of the CCR is established based on the ray tracing method to describe the ray trajectory inside the CCR. This ray tracing model could treat the general case that the optical beam is obliquely incident on the hypotenuse surface of the CCR with the dihedral angle error and surface nonflatness. Then, we integrate this general CCR model into the wave-optics (WO) simulation to construct the double-pass beam propagation simulation. This double-pass simulation contains the forward propagation from the transceiver to the MRR through the atmosphere, the retro-reflection of the CCR, and the backward propagation from the MRR to the transceiver, which can be realized by a single-pass WO simulation, the ray tracing CCR model, and another single-pass WO simulation, respectively. To verify the proposed CCR model and double-pass WO simulation, the effective reflection area, the incremental phase, and the reflected beam spot on the transceiver plane of the CCR are analyzed, and the numerical results are in agreement with the previously published results. Finally, we use the double-pass WO simulation to investigate the double-pass channel in the MRR FSO systems. The histograms of the turbulence-induced fading in the forward and backward channels are obtained from the simulation data and are fitted by gamma-gamma (ΓΓ) distributions. As the two opposite channels are highly correlated, we model the double-pass channel fading by the product of two correlated

  9. Automated cyclotron tuning using beam phase measurements

    International Nuclear Information System (INIS)

    Timmer, J.H.; Roecken, H.; Stephani, T.; Baumgarten, C.; Geisler, A.

    2006-01-01

    The ACCEL K250 superconducting cyclotron is specifically designed for the use in proton therapy systems. The compact medical 250 MeV proton accelerator fulfils all present and future beam requirements for fast scanning treatment systems and is delivered as a turn key system; no operator is routinely required. During operation of the cyclotron heat dissipation of the RF system induces a small drift in iron temperature. This temperature drift slightly detunes the magnetic field and small corrections must be made. A non-destructive beam phase detector has been developed to measure and quantify the effect of a magnetic field drift. Signal calculations were made and the design of the capacitive pickup probe was optimised to cover the desired beam current range. Measurements showed a very good agreement with the calculated signals and beam phase can be measured with currents down to 3 nA. The measured phase values are used as input for a feedback loop controlling the current in the superconducting coil. The magnetic field of the cyclotron is tuned automatically and online to maintain a fixed beam phase. Extraction efficiency is thereby optimised continuously and activation of the cyclotron is minimised. The energy and position stability of the extracted beam are well within specification

  10. Phase shifter for antenna beam steering

    Energy Technology Data Exchange (ETDEWEB)

    Jindal, Ravi, E-mail: rjindal21@gmail.com [Master’s(MS) in System Electronics and General Electrical, Ecole Polytechnique of university of Nantes France, IETR, Nantes (France); Razban, Tchanguiz, E-mail: tchanguiz.razban-haghighi@univ-nantes.fr [Electronics and Telecommunication Institute of Rennes (IETR-UMR 6164), Ecole Polytechnique of university of Nantes France, IETR, Nantes (France)

    2016-03-09

    Wide band Array Antenna operates in Ku-band (10.7-12.7 GHz) frequency composed of N×N radiating elements. This antenna aims at the reception of television satellite signals. The goal of this research is to provide better possibility of electronic beam control instead of manual or mechanical control, and design compact and low cost phase shifters to be inserted in the feeding network of this antenna. The electronic control of the phase shifter will allow the control of beam steering. The emphasis of this project will be done at the beginning on the design of a good phase shifter in Ku band. The aim of this research is to define, simulate, release and measure a continuous phase shifter. Better reflection loss, low transmission loss, low Cost of array antennas, large range of phase-shifter, phase flatness and bandwidth will be achieved by providing better gain.

  11. Phase shifter for antenna beam steering

    International Nuclear Information System (INIS)

    Jindal, Ravi; Razban, Tchanguiz

    2016-01-01

    Wide band Array Antenna operates in Ku-band (10.7-12.7 GHz) frequency composed of N×N radiating elements. This antenna aims at the reception of television satellite signals. The goal of this research is to provide better possibility of electronic beam control instead of manual or mechanical control, and design compact and low cost phase shifters to be inserted in the feeding network of this antenna. The electronic control of the phase shifter will allow the control of beam steering. The emphasis of this project will be done at the beginning on the design of a good phase shifter in Ku band. The aim of this research is to define, simulate, release and measure a continuous phase shifter. Better reflection loss, low transmission loss, low Cost of array antennas, large range of phase-shifter, phase flatness and bandwidth will be achieved by providing better gain.

  12. Beam splitter phase shifts: Wave optics approach

    Science.gov (United States)

    Agnesi, Antonio; Degiorgio, Vittorio

    2017-10-01

    We investigate the phase relationships between transmitted and reflected waves in a lossless beam splitter having a multilayer structure, using the matrix approach as outlined in classical optics books. Contrarily to the case of the quantum optics formalism generally employed to describe beam splitters, these matrices are not unitary. In this note we point out the existence of general relations among the elements of the transfer matrix that describes the multilayer beam splitter. Such relations, which are independent of the detailed structure of the beam splitter, fix the phase shifts between reflected and transmitted waves. It is instructive to see how the results obtained by Zeilinger by using spinor algebra and Pauli matrices can be easily derived from our general relations.

  13. Sensitive beam-bunch phase detector

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, S; Shepard, K W

    1984-11-15

    A sensitive heavy-ion beam-bunch phase detector has been developed by first examining the relationship between the sensitivity of an rf resonant cavity as a particle bunch detector and the shunt impedance of the same cavity as an accelerating structure. Then the various high shunt impedance rf cavities previously developed for accelerating heavy ions were evaluated for use as bunch detectors. A spiral-loaded geometry was chosen, built, and tested with beam. The sensitivity obtained, 14 V per electrical nA of beam, is a factor 3 higher than previously reported. (orig.).

  14. Sensitive beam-bunch phase detector

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, S; Shepard, K W [Argonne National Lab., IL (USA). Physics Div.

    1984-11-15

    A sensitive heavy-ion beam-bunch phase detector has been developed by first examining the relationship between the sensitivity of an RF resonant cavity as a particle bunch detector and the shunt impedance of the same cavity as an accelerating structure. Then the various high shunt impedance RF cavities previously developed for accelerating heavy ions were evaluated for use as bunch detectors. A spiral-loaded geometry was chosen, built, and tested with beam. The sensitivity obtained, 14 ..mu.. V per electrical nA of beam, is a factor 3 higher than previously reported.

  15. Study of two-phase flow redistribution between two passes of a heat exchanger

    International Nuclear Information System (INIS)

    Mendes de Moura, L.F.

    1989-04-01

    The object of the present thesis deals with the study of two-phase flow redistribution between two passes of a heat exchanger. Mass flow rate measurements of each component performed at each channel outlet of the second pass allowed us to determine the influence of mass flow, gas quality, flow direction (upward or downward) and common header geometry upon flow redistribution. Local void fraction inside common header was measured with an optical probe. A two-dimensional two-phase flow computational code was developed from a two-fluid model. Modelling of interfacial momentum transfer was used in order to take into account twp-phase flow patterns in common headers. Numerical simulation results show qualitative agreement with experimental results. Present theoretical model limitations are analysed and future improvements are proposed [fr

  16. Microstrip linear phase low pass filter based on defected ground structures for partial response modulation

    DEFF Research Database (Denmark)

    Cimoli, Bruno; Johansen, Tom Keinicke; Olmos, Juan Jose Vegas

    2018-01-01

    We report a high performance linear phase low pass filter (LPF) designed for partial response (PR) modulations. For the implementation, we adopted microstrip technology and a variant of the standard stepped‐impedance technique. Defected ground structures (DGS) are used for increasing the characte......We report a high performance linear phase low pass filter (LPF) designed for partial response (PR) modulations. For the implementation, we adopted microstrip technology and a variant of the standard stepped‐impedance technique. Defected ground structures (DGS) are used for increasing...... the characteristic impedance of transmission lines. Experimental results prove that the proposed filter can successfully modulate a non‐return‐to‐zero (NRZ) signal into a five levels PR one....

  17. Global and local characteristics of an autogenous single pass electron beam weld in thick gage UNS S41500 steel

    Energy Technology Data Exchange (ETDEWEB)

    Sarafan, S., E-mail: Sheida.Sarafan.1@ens.etsmtl.ca [École de Technologie Supérieure, Montréal, Québec, Canada H3C 1K3 (Canada); National Research Council Canada, Aerospace, Montréal, Québec, Canada H3T 2B2 (Canada); Wanjara, P., E-mail: priti.wanjara@nrc-cnrc.gc.ca [National Research Council Canada, Aerospace, Montréal, Québec, Canada H3T 2B2 (Canada); Gholipour, J., E-mail: Javad.gholipour@nrc-cnrc.gc.ca [National Research Council Canada, Aerospace, Montréal, Québec, Canada H3T 2B2 (Canada); Champliaud, H., E-mail: henri.champliaud@etsmtl.ca [École de Technologie Supérieure, Montréal, Québec, Canada H3C 1K3 (Canada)

    2016-06-01

    Electron beam welding of UNS S41500, a low carbon martensitic stainless steel utilized in hydroelectric turbine manufacturing, was investigated by applying a single pass autogenous process to penetrate a section thickness of 72 mm without preheating. In the as-welded and post-weld heat treated conditions, the evolution in microhardness and microstructure across the weldments, as well as the global and local tensile properties, were evaluated. In the as-welded condition, assessment of the microhardness and the associated microstructure across the welds led to the identification of six regions, including the fusion zone, four heat affected zones and the base metal; each of these regions consisted of different phase constituents, such as tempered martensite, untempered martensite, delta ferrite and retained austenite. Post-weld heat treatment, undertaken to temper the untempered martensite in the as-welded microstructure, was effective in homogenizing the hardness across the weldment. The mechanical response of the welds, determined through tensile testing at room temperature with an automated non-contact three-dimensional deformation measurement system, indicated that the global tensile properties in the as-welded and post-weld heat treated conditions met the acceptance criteria in the ASME Section IX standard. Also, evaluation of the local tensile properties in the fusion and heat affected zones of the as-welded samples allowed a more comprehensive understanding of the strength and ductility associated with the different microstructures in the “composite” nature of the weldment. Fractographic analysis demonstrated dimpled features on the tensile fracture surfaces and failure was associated with debonding between the martensitic matrix and the secondary phases (such as delta ferrite and retained austenite) that resulted in the formation, growth and coalescence of voids into a macroscale crack.

  18. A multiple-pass ring oscillator based dual-loop phase-locked loop

    International Nuclear Information System (INIS)

    Chen Danfeng; Ren Junyan; Deng Jingjing; Li Wei; Li Ning

    2009-01-01

    A dual-loop phase-locked loop (PLL) for wideband operation is proposed. The dual-loop architecture combines a coarse-tuning loop with a fine-tuning one, enabling a wide tuning range and low voltage-controlled oscillator (VCO) gain without poisoning phase noise and reference spur suppression performance. An analysis of the phase noise and reference spur of the dual-loop PLL is emphasized. A novel multiple-pass ring VCO is designed for the dual-loop application. It utilizes both voltage-control and current-control simultaneously in the delay cell. The PLL is fabricated in Jazz 0.18-μm RF CMOS technology. The measured tuning range is from 4.2 to 5.9 GHz. It achieves a low phase noise of -99 dBc/Hz - 1 MHz offset from a 5.5 GHz carrier.

  19. A multiple-pass ring oscillator based dual-loop phase-locked loop

    Energy Technology Data Exchange (ETDEWEB)

    Chen Danfeng; Ren Junyan; Deng Jingjing; Li Wei; Li Ning, E-mail: dfchen@fudan.edu.c [State Key Laboratory of ASIC and System, Fudan University, Shanghai 201203 (China)

    2009-10-15

    A dual-loop phase-locked loop (PLL) for wideband operation is proposed. The dual-loop architecture combines a coarse-tuning loop with a fine-tuning one, enabling a wide tuning range and low voltage-controlled oscillator (VCO) gain without poisoning phase noise and reference spur suppression performance. An analysis of the phase noise and reference spur of the dual-loop PLL is emphasized. A novel multiple-pass ring VCO is designed for the dual-loop application. It utilizes both voltage-control and current-control simultaneously in the delay cell. The PLL is fabricated in Jazz 0.18-{mu}m RF CMOS technology. The measured tuning range is from 4.2 to 5.9 GHz. It achieves a low phase noise of -99 dBc/Hz - 1 MHz offset from a 5.5 GHz carrier.

  20. Tomography of the electron beam transverse phase space at PITZ

    Energy Technology Data Exchange (ETDEWEB)

    Asova, Galina

    2013-09-15

    The operation of a Free Elector Laser, FEL, requires high energy, high peak current electron beams with small transverse emittance. In the contemporary FELs, the electron beam is passed through a periodic magnetic structure - an undulator - which modifies the straight beam trajectory into a sinusoidal one, where FEL light is generated at each bend. According to the energy, the transverse emittance and the peak current of the beam and the parameters of the undulator, FEL radiation with wavelength in the range of nano- to micrometers can be generated. Studies and development of FELs are done all over the world. The Free electron LASer in Hamburg, FLASH, and the international European X-ray FEL, XFEL, in Hamburg, Germany, are two leading projects of the Deutsches Elektronen SYnchrotron, DESY. Part of the research program on FELs in DESY is realized in Zeuthen within the project Photo-Injector Test Facility at DESY in Zeuthen, PITZ. PITZ is an international collaboration including Germany, Russia, Italy, France, Bulgaria, Thailand, United Kingdom. The Institute of Nuclear Research and Nuclear Energy, INRNE, at the Bulgarian Academy of Sciences participates from bulgarian side. PITZ studies and optimizes the photo-injectors for FLASH and the XFEL. The research program emphasizes on detailed measurements of the transverse phase-space density distribution. Until 2010 the single slit scan technique has been used to measure the beam transverse distributions. At the end of 2010 a module for tomographic diagnostics has been installed which extends the possibilities of PITZ to measure simultaneously the two transverse planes of a single micropulse with improved signal-to-noise ratio. The difficult conditions of low emittance for high bunch charge and low energy make the operation of the module challenging. This thesis presents the design considerations for the tomography module, a number of reconstruction algorithms and their applicability to limited data sets, the influence

  1. Tomography of the electron beam transverse phase space at PITZ

    International Nuclear Information System (INIS)

    Asova, Galina

    2013-09-01

    The operation of a Free Elector Laser, FEL, requires high energy, high peak current electron beams with small transverse emittance. In the contemporary FELs, the electron beam is passed through a periodic magnetic structure - an undulator - which modifies the straight beam trajectory into a sinusoidal one, where FEL light is generated at each bend. According to the energy, the transverse emittance and the peak current of the beam and the parameters of the undulator, FEL radiation with wavelength in the range of nano- to micrometers can be generated. Studies and development of FELs are done all over the world. The Free electron LASer in Hamburg, FLASH, and the international European X-ray FEL, XFEL, in Hamburg, Germany, are two leading projects of the Deutsches Elektronen SYnchrotron, DESY. Part of the research program on FELs in DESY is realized in Zeuthen within the project Photo-Injector Test Facility at DESY in Zeuthen, PITZ. PITZ is an international collaboration including Germany, Russia, Italy, France, Bulgaria, Thailand, United Kingdom. The Institute of Nuclear Research and Nuclear Energy, INRNE, at the Bulgarian Academy of Sciences participates from bulgarian side. PITZ studies and optimizes the photo-injectors for FLASH and the XFEL. The research program emphasizes on detailed measurements of the transverse phase-space density distribution. Until 2010 the single slit scan technique has been used to measure the beam transverse distributions. At the end of 2010 a module for tomographic diagnostics has been installed which extends the possibilities of PITZ to measure simultaneously the two transverse planes of a single micropulse with improved signal-to-noise ratio. The difficult conditions of low emittance for high bunch charge and low energy make the operation of the module challenging. This thesis presents the design considerations for the tomography module, a number of reconstruction algorithms and their applicability to limited data sets, the influence

  2. Alteration in non-classicality of light on passing through a linear polarization beam splitter

    Science.gov (United States)

    Shukla, Namrata; Prakash, Ranjana

    2016-06-01

    We observe the polarization squeezing in the mixture of a two mode squeezed vacuum and a simple coherent light through a linear polarization beam splitter. Squeezed vacuum not being squeezed in polarization, generates polarization squeezed light when superposed with coherent light. All the three Stokes parameters of the light produced on the output port of polarization beam splitter are found to be squeezed and squeezing factor also depends upon the parameters of coherent light.

  3. Laser beam complex amplitude measurement by phase diversity.

    Science.gov (United States)

    Védrenne, Nicolas; Mugnier, Laurent M; Michau, Vincent; Velluet, Marie-Thérèse; Bierent, Rudolph

    2014-02-24

    The control of the optical quality of a laser beam requires a complex amplitude measurement able to deal with strong modulus variations and potentially highly perturbed wavefronts. The method proposed here consists in an extension of phase diversity to complex amplitude measurements that is effective for highly perturbed beams. Named camelot for Complex Amplitude MEasurement by a Likelihood Optimization Tool, it relies on the acquisition and processing of few images of the beam section taken along the optical path. The complex amplitude of the beam is retrieved from the images by the minimization of a Maximum a Posteriori error metric between the images and a model of the beam propagation. The analytical formalism of the method and its experimental validation are presented. The modulus of the beam is compared to a measurement of the beam profile, the phase of the beam is compared to a conventional phase diversity estimate. The precision of the experimental measurements is investigated by numerical simulations.

  4. A low-cost non-intercepting beam current and phase monitor for heavy ions

    International Nuclear Information System (INIS)

    Bogaty, J.M.; Clifft, B.E.

    1995-01-01

    A low cost ion beam measurement system has been developed for use at ATLAS. The system provides nondestructive phase and intensity measurement of passing ion beam bunches by sensing their electric fields. Bunches traverse a short tubular electrode thereby inducing displacement currents. These currents are brought outside the vacuum jacket where a lumped inductance resonates electrode capacitance at one of the bunching harmonic frequencies. This configuration yields a basic sensitivity of a few hundred millivolts signal per microampere of beam current. Beam induced radiofrequency signals are summed against an offset frequency generated by the master oscillator. The resulting difference frequency conveys beam intensity and bunch phase information which is sent to separate processing channels. One channel utilizes a phase locked loop to stabilize phase readings during microsecond beam drop outs. The other channel uses a linear full-wave active rectifier circuit which converts sine wave signal amplitude to a DC voltage representing beam current. Plans are in progress to install this new diagnostic at several locations in ATLAS which should help shorten the tuning cycle of new ion species

  5. Noninterferometric phase imaging of a neutral atomic beam

    International Nuclear Information System (INIS)

    Fox, P.J.; Mackin, T.R.; Turner, L.D.; Colton, I.; Nugent, K.A.; Scholten, R.E.

    2002-01-01

    We demonstrate quantitative phase imaging of a neutral atomic beam by using a noninterferometric technique. A collimated thermal atomic beam is phase shifted by an off-resonant traveling laser beam with both a Gaussian and a TEM 01 profile and with both red and blue detuning of as much as 50 GHz. Phase variations of more than 1000 rad were recovered from velocity-selective measurements of the propagation of the atomic beam and were found to be in quantitative agreement with theoretical predictions based on independently measured phase object intensity profiles and detunings

  6. Gyrator transform of Gaussian beams with phase difference and generation of hollow beam

    Science.gov (United States)

    Xiao, Zhiyu; Xia, Hui; Yu, Tao; Xie, Ding; Xie, Wenke

    2018-03-01

    The optical expression of Gaussian beams with phase difference, which is caused by gyrator transform (GT), has been obtained. The intensity and phase distribution of transform Gaussian beams are analyzed. It is found that the circular hollow vortex beam can be obtained by overlapping two GT Gaussian beams with π phase difference. The effect of parameters on the intensity and phase distributions of the hollow vortex beam are discussed. The results show that the shape of intensity distribution is significantly influenced by GT angle α and propagation distance z. The size of the hollow vortex beam can be adjusted by waist width ω 0. Compared with previously reported results, the work shows that the hollow vortex beam can be obtained without any model conversion of the light source.

  7. RF Phase Scan for Beam Energy Measurement of KOMAC DTL

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hansung; Kwon, Hyeokjung; Kim, Seonggu; Lee, Seokgeun; Cho, Yongsub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    The energy gain through the drift tube linac is a function of the synchronous phase, therefore, the output beam energy from DTL can be affected by the RF phase setting in low-level RF (LLRF) system. The DTL at Korea Multi-purpose Accelerator Complex (KOMAC) consists of 11 tanks and the RF phase setting in each tank should be matched for synchronous acceleration in successive tanks. That means a proper setting of RF phase in each DTL tank is critical for efficient and loss-free operation. The matching RF phase can be determined based on the output energy measurement from the DTL tank. The beam energy can be measured by several methods. For example, we can use a bending magnet to determine the beam energy because the higher momentum of beam means the less deflection angle in the fixed magnetic field. By measuring the range of proton beam through a material with known stopping power also can be utilized to determine the beam energy. We used a well-known time-of-flight method to determine the output beam energy from the DTL tank by measuring beam phase with a beam position monitor (BPM). Based on the energy measurement results, proper RF operating point could be obtained. We performed a RF phase scan to determine the output beam energy from KOMAC DTL by using a time-of-flight method and to set RF operating point precisely. The measured beam energy was compared with a beam dynamics simulation and showed a good agreement. RF phase setting is critical issue for the efficient operation of the proton accelerator, we have a plan to implement and integrate the RF phase measurement system into an accelerator control system for future need.

  8. Superconducting resonator used as a beam phase detector

    Directory of Open Access Journals (Sweden)

    S. I. Sharamentov

    2003-05-01

    Full Text Available Beam-bunch arrival time has been measured for the first time by operating superconducting cavities, normally part of the linac accelerator array, in a bunch-detecting mode. The very high Q of the superconducting cavities provides high sensitivity and allows for phase-detecting low-current beams. In detecting mode, the resonator is operated at a very low field level comparable to the field induced by the bunched beam. Because of this, the rf field in the cavity is a superposition of a “pure” (or reference rf and the beam-induced signal. A new method of circular phase rotation (CPR, allowing extraction of the beam phase information from the composite rf field was developed. Arrival time phase determination with CPR is better than 1° (at 48 MHz for a beam current of 100 nA. The electronics design is described and experimental data are presented.

  9. Beam envelope profile of non-centrosymmetric polygonal phase space

    International Nuclear Information System (INIS)

    Chen Yinbao; Xie Xi

    1984-01-01

    The general theory of beam envelope profile of non-centrosymmetric polygonal phase space is developed. By means of this theory the beam envelope profile of non-centrosymmetric polygonal phase space can be calculated directly. An example is carried out in detail to show the practical application of the theory

  10. Highly efficient electron vortex beams generated by nanofabricated phase holograms

    Energy Technology Data Exchange (ETDEWEB)

    Grillo, Vincenzo, E-mail: vincenzo.grillo@nano.cnr.it [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); CNR-IMEM Parco Area delle Scienze 37/A, I-43124 Parma (Italy); Carlo Gazzadi, Gian [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Karimi, Ebrahim [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5 (Canada); Mafakheri, Erfan [Dipartimento di Fisica Informatica e Matematica, Università di Modena e Reggio Emilia, via G Campi 213/a, I-41125 Modena (Italy); Boyd, Robert W. [Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5 (Canada); Frabboni, Stefano [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Dipartimento di Fisica Informatica e Matematica, Università di Modena e Reggio Emilia, via G Campi 213/a, I-41125 Modena (Italy)

    2014-01-27

    We propose an improved type of holographic-plate suitable for the shaping of electron beams. The plate is fabricated by a focused ion beam on a silicon nitride membrane and introduces a controllable phase shift to the electron wavefunction. We adopted the optimal blazed-profile design for the phase hologram, which results in the generation of highly efficient (25%) electron vortex beams. This approach paves the route towards applications in nano-scale imaging and materials science.

  11. Highly efficient electron vortex beams generated by nanofabricated phase holograms

    International Nuclear Information System (INIS)

    Grillo, Vincenzo; Carlo Gazzadi, Gian; Karimi, Ebrahim; Mafakheri, Erfan; Boyd, Robert W.; Frabboni, Stefano

    2014-01-01

    We propose an improved type of holographic-plate suitable for the shaping of electron beams. The plate is fabricated by a focused ion beam on a silicon nitride membrane and introduces a controllable phase shift to the electron wavefunction. We adopted the optimal blazed-profile design for the phase hologram, which results in the generation of highly efficient (25%) electron vortex beams. This approach paves the route towards applications in nano-scale imaging and materials science

  12. Numerical Calculation of the Phase Space Density for the Strong-Strong Beam-Beam Interaction

    International Nuclear Information System (INIS)

    Sobol, A.; Ellison, J.A.

    2003-01-01

    We developed a parallel code to calculate the evolution of the 4D phase space density of two colliding beams, which are coupled via the collective strong-strong beam-beam interaction, in the absence of diffusion and damping, using the Perron-Frobenius (PF) operator technique

  13. The effects of betatron phase advances on beam-beam and its compensation in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Y.; Fischer, W.; Gu, X.; Tepikian, S.; Trbojevic, D.

    2011-03-28

    In this article we perform simulation studies to investigate the effects of betatron phase advances between the beam-beam interaction points on half-integer resonance driving term, second order chromaticty and dynamic aperture in RHIC. The betatron phase advances are adjusted with artificial matrices inserted in the middle of arcs. The lattices for the 2011 RHIC polarized proton (p-p) run and 2010 RHIC Au-Au runs are used in this study. We also scan the betatron phase advances between IP8 and the electron lens for the proposed Blue ring lattice with head-on beam-beam compensation.

  14. Overview of Phase Space Manipulations of Relativistic Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Dao; /SLAC

    2012-08-31

    Phase space manipulation is a process to rearrange beam's distribution in 6-D phase space. In this paper, we give an overview of the techniques for tailoring beam distribution in 2D, 4D, and 6D phase space to meet the requirements of various applications. These techniques become a new focus of accelerator physics R&D and very likely these advanced concepts will open up new opportunities in advanced accelerators and the science enabled by them.

  15. Overview of Phase Space Manipulations of Relativistic Electron Beams

    International Nuclear Information System (INIS)

    Xiang, Dao

    2012-01-01

    Phase space manipulation is a process to rearrange beam's distribution in 6-D phase space. In this paper, we give an overview of the techniques for tailoring beam distribution in 2D, 4D, and 6D phase space to meet the requirements of various applications. These techniques become a new focus of accelerator physics R and D and very likely these advanced concepts will open up new opportunities in advanced accelerators and the science enabled by them.

  16. Multi-pass spectroscopic ellipsometry

    International Nuclear Information System (INIS)

    Stehle, Jean-Louis; Samartzis, Peter C.; Stamataki, Katerina; Piel, Jean-Philippe; Katsoprinakis, George E.; Papadakis, Vassilis; Schimowski, Xavier; Rakitzis, T. Peter; Loppinet, Benoit

    2014-01-01

    Spectroscopic ellipsometry is an established technique, particularly useful for thickness measurements of thin films. It measures polarization rotation after a single reflection of a beam of light on the measured substrate at a given incidence angle. In this paper, we report the development of multi-pass spectroscopic ellipsometry where the light beam reflects multiple times on the sample. We have investigated both theoretically and experimentally the effect of sample reflectivity, number of reflections (passes), angles of incidence and detector dynamic range on ellipsometric observables tanΨ and cosΔ. The multiple pass approach provides increased sensitivity to small changes in Ψ and Δ, opening the way for single measurement determination of optical thickness T, refractive index n and absorption coefficient k of thin films, a significant improvement over the existing techniques. Based on our results, we discuss the strengths, the weaknesses and possible applications of this technique. - Highlights: • We present multi-pass spectroscopic ellipsometry (MPSE), a multi-pass approach to ellipsometry. • Different detectors, samples, angles of incidence and number of passes were tested. • N passes improve polarization ratio sensitivity to the power of N. • N reflections improve phase shift sensitivity by a factor of N. • MPSE can significantly improve thickness measurements in thin films

  17. Phase space measurements at non-accessible point on the beam path of an accelerator facility

    International Nuclear Information System (INIS)

    Hassan, A.

    2004-01-01

    The optimization of beam lines for particles extracted from accelerator facilities requires the knowledge of beam parameters. A method for the measurement of phase space and beam intensity distribution is represented. This method depends on the setting of quadrupole lenses that allows the imaging of beam profiles at arbitrary positions along the beam path on the same multi-wire proportional chamber, where the intensity distribution can be evaluated. The necessary focusing powers for a certain imaging task are calculated in a thin lens approximation. The corresponding focusing power for thick quadrupole lenses are calculated using the PC transport program. A comparison of the calculated focusing powers for thin and thick lenses reveals deviations at the highest field strengths, due to saturation effect. The position of the beam waist in normal and angular space is directly calculated and visualized. The horizontal and vertical waist positions are found to be rather independent of the beam energy. Extensive calculation was done to study the effect of a reduced aperture on the maximum beam emittances aa x and aa y of the extracted particles. The main result shows that the maximum emittance passing through depends on the waist distant and the diameter of the reduced aperture. (orig.)

  18. Phase space model for transmission of light beam

    International Nuclear Information System (INIS)

    Fu Shinian

    1989-01-01

    Based on Fermat's principle of ray optics, the Hamiltonian of an optical ray is derived by comparison with classical mechanics. A phase space model of light beam is proposed, assuming that the light beam, regarded as a group of rays, can be described by an ellipse in the μ-phase space. Therefore, the transmission of light beam is represented by the phase space matrix transformation. By means of this non-wave formulation, the same results are obtained as those from wave equation such as Kogelnik's ABCD law. As an example of the application on this model, the matching problem of optical cavity is solved

  19. High precision capacitive beam phase probe for KHIMA project

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Ji-Gwang, E-mail: windy206@hanmail.net [Korea Institute of Radiological and Medical Sciences, 215–4, Gongneung-dong, Nowon-t, Seoul 139–706 (Korea, Republic of); Yang, Tae-Keun [Korea Institute of Radiological and Medical Sciences, 215–4, Gongneung-dong, Nowon-t, Seoul 139–706 (Korea, Republic of); Forck, Peter [GSI Helmholtz Centre for Ion Research, Darmstadt 64291, German (Germany)

    2016-11-21

    In the medium energy beam transport (MEBT) line of KHIMA project, a high precision beam phase probe monitor is required for a precise tuning of RF phase and amplitude of Radio Frequency Quadrupole (RFQ) accelerator and IH-DTL linac. It is also used for measuring a kinetic energy of ion beam by time-of-flight (TOF) method using two phase probes. The capacitive beam phase probe has been developed. The electromagnetic design of the high precision phase probe was performed to satisfy the phase resolution of 1° (@200 MHz). It was confirmed by the test result using a wire test bench. The measured phase accuracy of the fabricated phase probe is 1.19 ps. The pre-amplifier electronics with the 0.125 ∼ 1.61 GHz broad-band was designed and fabricated for amplifying the signal strength. The results of RF frequency and beam energy measurement using a proton beam from the cyclotron in KIRAMS is presented.

  20. Beam-phase monitoring with non-destructive pickup

    International Nuclear Information System (INIS)

    Bogaty, J.; Clifft, B.E.

    1995-01-01

    An intensity and phase-sensitive capacitive pickup was installed at the entrance to the PII linac. This device is based on an extension of the design of the Beam Current Monitor developed as part of the ATLAS radiation safety system. The purpose of the pickup is to allow the arrival phase of the beam from the ECR source at the entrance to the PII linac to be set to a standard which reproduces previous tune conditions and establishes a standard. The new pickups and associated electronics demonstrated sensitivity well below 1 electrical nanoamp but can handle beam currents of many electrical microamps as well. In addition to phase information, beam current is also measured by the units thus providing a continuous, non-intercepting current readout as well. From the very first use of PII, we established a few open-quotes reference tunesclose quotes for the linac and scaled those tunes for any other beam desired. For such scaling to work properly, the velocity and phase of the beam from the ion source must be fixed and reproducible. In last year's FWP the new ATLAS Master Oscillator System was described. The new system has the ability of easily adjusting the beam arrival phase at the entrance to each of the major sections of the facility - PII, Booster, ATLAS. Our present techniques for establishing the beam arrival phase at the entrance of each of the linac sections are cumbersome and, sometimes, intellectually challenging. The installation of these capacitative pickups at the entrance to each of the linac sections will make the determination and setting of the beam arrival phase direct, simple, and dynamic. This should dramatically shorten our setup time for open-quotes old-tuneclose quotes configurations and increase useful operating hours. Permanent electronics for the PII entrance pickup is under construction

  1. Concept of an interlaced phased array for beam switching

    Science.gov (United States)

    Reddy, C. A.; Janardhanan, K. V.; Mukundan, K. K.; Shenoy, K. S. V.

    1990-04-01

    A novel concept is described for feeding and phasing a large linear array of N antenna elements using only three or five feed points and phase shifters and still achieving beam switching. The idea consists of drastically reducing the number of input points by interlacing a small number of serially fed subarrays which are suitably phased. This so-called interlaced phased array (IPA) concept was tested using an array of 15 four-element Yagi antennas with a spacing equal to 0.8 wavelengths and found feasible. Some of the distinct advantages of the IPA in comparison with a conventional system of beam switching are reduced power loss, reduced phasing errors, reduced cost, increased reliability resulting from greatly reduced number of phase shifters, and better symmetry of off-zenith beams.

  2. A Phase-Controlled Optical Parametric Amplifier Pumped by Two Phase-Distorted Laser Beams

    International Nuclear Information System (INIS)

    Hong-Yan, Ren; Lie-Jia, Qian; Peng, Yuan; He-Yuan, Zhu; Dian-Yuan, Fan

    2010-01-01

    We theoretically study the phase characteristic of optical parametric amplification (OPA) or chirped pulse OPA (OPCPA) pumped by two phase-distorted laser beams. In the two-beam-pumped optical parametric amplification (TBOPA), due to spatial walk-off, both of the pump phase distortions will be partly transferred to signal in a single crystal so as to degrade the signal beam-quality, which will be more serious in high-energy OPCPA. An OPA configuration with a walkoff-compensated crystal pair is demonstrated for reducing the signal phase distortion experienced in the first stage and ensuring the signal phase independent of two pump phase distortions through the second crystal, hence maintaining the signal beam-quality. Such a TBOPA is similar to the conventional quantum laser amplifier by means of eliminating its sensitivity to the phase and number of the pump beams

  3. Phase Memory Preserving Harmonics from Abruptly Autofocusing Beams.

    Science.gov (United States)

    Koulouklidis, Anastasios D; Papazoglou, Dimitris G; Fedorov, Vladimir Yu; Tzortzakis, Stelios

    2017-12-01

    We demonstrate both theoretically and experimentally that the harmonics from abruptly autofocusing ring-Airy beams present a surprising property: They preserve the phase distribution of the fundamental beam. Consequently, this "phase memory" imparts to the harmonics the abrupt autofocusing behavior, while, under certain conditions, their foci coincide in space with the one of the fundamental. Experiments agree well with our theoretical estimates and detailed numerical calculations. Our findings open the way for the use of such beams and their harmonics in strong field science.

  4. Beam position and phase measurements of microampere beams at the Michigan State University REA3 facility

    CERN Document Server

    Crisp, J; Durickovic, B; Kiupel, G; Krause, S; Leitner, D; Nash, S; Rodriguez, J A; Russo, T; Webber, R; Wittmer, W; Eddy, N; Briegel, C; Fellenz, B; Slimmer, D; Wendt, M

    2013-01-01

    A high power CW, heavy ion linac will be the driver accelerator for the Facility for Rare Isotope Beams (FRIB) being designed at Michigan State University (MSU). The linac requires a Beam Position Monitoring (BPM) system with better than 100 micron resolution at 100 microamperes beam current. A low beam current test of the candidate technology, button pick-ups and direct digital down-conversion signal processing, was conducted in the ReA3 re-accelerated beam facility at Michigan State University. The test is described. Beam position and phase measurement results, demonstrating ~250 micron and ~1.5 degree resolution in a 45 kHz bandwidth for a 1.0 microampere beam current, are reported.

  5. A device for automated phase space measurement of ion beams

    International Nuclear Information System (INIS)

    Lukas, J.; Priller, A.; Steier, P.

    2007-01-01

    Equipment for automated phase-space measurements was developed at the VERA Lab. The measurement of the beam's intensity distribution, as well as its relative position with respect to the reference orbit is performed at two locations along the beam line. The device basically consists of moveable slits and a beam profile monitor, which are both coordinated and controlled by an embedded controller. The operating system of the controller is based on Linux with real-time extension. It controls the movement of the slits and records the data synchronized to the movement of the beam profile monitor. The data is sent via TCP/IP to the data acquisition system of VERA where visualization takes place. The duration of one phase space measurement is less than 10 s, which allows for using the device during routine beam tuning

  6. Direction-dependent waist-shift-difference of Gaussian beam in a multiple-pass zigzag slab amplifier and geometrical optics compensation method.

    Science.gov (United States)

    Li, Zhaoyang; Kurita, Takashi; Miyanaga, Noriaki

    2017-10-20

    Zigzag and non-zigzag beam waist shifts in a multiple-pass zigzag slab amplifier are investigated based on the propagation of a Gaussian beam. Different incident angles in the zigzag and non-zigzag planes would introduce a direction-dependent waist-shift-difference, which distorts the beam quality in both the near- and far-fields. The theoretical model and analytical expressions of this phenomenon are presented, and intensity distributions in the two orthogonal planes are simulated and compared. A geometrical optics compensation method by a beam with 90° rotation is proposed, which not only could correct the direction-dependent waist-shift-difference but also possibly average the traditional thermally induced wavefront-distortion-difference between the horizontal and vertical beam directions.

  7. Self-Nulling Beam Combiner Using No External Phase Inverter

    Science.gov (United States)

    Bloemhof, Eric E.

    2010-01-01

    A self-nulling beam combiner is proposed that completely eliminates the phase inversion subsystem from the nulling interferometer, and instead uses the intrinsic phase shifts in the beam splitters. Simplifying the flight instrument in this way will be a valuable enhancement of mission reliability. The tighter tolerances on R = T (R being reflection and T being transmission coefficients) required by the self-nulling configuration actually impose no new constraints on the architecture, as two adaptive nullers must be situated between beam splitters to correct small errors in the coatings. The new feature is exploiting the natural phase shifts in beam combiners to achieve the 180 phase inversion necessary for nulling. The advantage over prior art is that an entire subsystem, the field-flipping optics, can be eliminated. For ultimate simplicity in the flight instrument, one might fabricate coatings to very high tolerances and dispense with the adaptive nullers altogether, with all their moving parts, along with the field flipper subsystem. A single adaptive nuller upstream of the beam combiner may be required to correct beam train errors (systematic noise), but in some circumstances phase chopping reduces these errors substantially, and there may be ways to further reduce the chop residuals. Though such coatings are beyond the current state of the art, the mechanical simplicity and robustness of a flight system without field flipper or adaptive nullers would perhaps justify considerable effort on coating fabrication.

  8. Source reconstruction using phase space beam summation technique

    International Nuclear Information System (INIS)

    Graubart, Gideon.

    1990-10-01

    In this work, the phase-space beam summation technique (PSBS), is applied to back propagation and inverse source problems. The PSBS expresses the field as a superposition of shifted and tilted beams. This phase space spectrum of beams is matched to the source distribution via an amplitude function which expresses the local spectrum of the source function in terms of a local Fourier transform. In this work, the emphasis is on the phase space processing of the data, on the information content of this data and on the back propagation scheme. More work is still required to combine this back propagation approach in a full, multi experiment inverse scattering scheme. It is shown that the phase space distribution of the data, computed via the local spectrum transform, is localized along lines that define the local arrival direction of the wave data. We explore how the choice of the beam width affects the compactification of this distribution, and derive criteria for choosing a window that optimizes this distribution. It should be emphasized that compact distribution implies fewer beams in the back propagation scheme and therefore higher numerical efficiency and better physical insight. Furthermore it is shown how the local information property of the phase space representation can be used to improve the performance of this simple back propagation problem, in particular with regard to axial resolution; the distance to the source can be determined by back propagating only the large angle phase space beams that focus on the source. The information concerning transverse distribution of the source, on the other hand, is contained in the axial phase space region and can therefore be determined by the corresponding back propagating beams. Because of the global nature of the plane waves propagators the conventional plane wave back propagation scheme does not have the same 'focusing' property, and therefore suffers from lack of information localization and axial resolution. The

  9. Phase space treatment of optical beams

    International Nuclear Information System (INIS)

    Nemes, G.; Teodorescu, I.E.; Nemes, M.

    1984-01-01

    The lecture reveals the possibility of treating optical beams and systems using the PS concept. In the first part some well-known concepts and results of charged particle optics are applied to optical beam and systems. Attention is paid to the PSE concept as to beina a beam invariant according to Liouville's theorem. In the second part some simple optical sources, their PSE and their transforms through simple optical elements are theoretically presented. An experimental method and a device for PSE measurements are presented in the third part. In the fourth part the main problems of the linear system theory which were applied to electrical circuits in the time (or freo.uency) domain and to optical systems in the bidimensional space of spatial coordinates (or spatial frequencies) are applied to stigmatic optical systems in the bidimensional PS (spatial coordinate, angle). Some examples of applying PS concepts in optics are presented in the fifth part. The lecture is mainly based on original results some of them being previously unpublished. (authors)

  10. Digital beam position and phase monitor for P-LINAC for FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Almalki, Mohammed

    2013-07-01

    For the planned P-LINAC for the FAIR facility, Beam Position Monitors (BPM) will be installed at 14 locations along the LINAC. The digital signal processing to derive the transverse beam position and the beam phase will be implemented by ''Libera Single Pass H''. The specification for position measurement is 0.1 mm spatial resolution and phase accuracy is 1 degree with respect to 325 MHz acceleration frequency. The results from the Libera digital signal processing were compared with the time-domain approach and the FFT analytic calculations. The first test was performed at the GSI UNILAC with a Ne4+ beam at 1.4 MeV / u. A single BPM was used to act as a ''Bunch arrival monitor'' to characterize the dependence of beam arrival time on bunch shape. The signals were sampled at 117.440 MHz with a 16-bit ADC to produce I and Q data streams. The first experimental results are reported.

  11. Geometrical theory of nonlinear phase distortion of intense laser beams

    International Nuclear Information System (INIS)

    Glaze, J.A.; Hunt, J.T.; Speck, D.R.

    1975-01-01

    Phase distortion arising from whole beam self-focusing of intense laser pulses with arbitrary spatial profiles is treated in the limit of geometrical optics. The constant shape approximation is used to obtain the phase and angular distribution of the geometrical rays in the near field. Conditions for the validity of this approximation are discussed. Geometrical focusing of the aberrated beam is treated for the special case of a beam with axial symmetry. Equations are derived that show both the shift of the focus and the distortion of the intensity distribution that are caused by the nonlinear index of refraction of the optical medium. An illustrative example treats the case of beam distortion in a Nd:Glass amplifier

  12. Experimental investigation of the characteristics of a laser beam passing through a fluid layer for surface quality in-process measurement

    International Nuclear Information System (INIS)

    Guo, Ruipeng; Tao, Zhengsu

    2010-01-01

    The optical characteristics of a laser beam passing through a fluid parallel layer are examined through a series of experimental tests in this project. The experimental apparatus consists of a bare surface quality measurement system and a fluid-supporting system. In the case of laser beam propagation through the static fluid layer, a modified Beckmann–Kirchhoff scattering model has been developed. Based on this model, the results of the surface quality in-process optical measurement can be amended. By extracting a ratio parameter from the image of the scattered light pattern to estimate surface roughness, the modified model can be verified quantitatively in the experimental system. As far as laser beam propagation through the flowing fluid layer is concerned, the deflection of the laser beam caused by fluid flow is small. The experiments are conducted to investigate the characteristics, and the results show that the resulting measurement error for surface quality optical measurement is in an acceptable range

  13. Beam Position and Phase Monitor - Wire Mapping System

    International Nuclear Information System (INIS)

    Watkins, Heath A.; Shurter, Robert B.; Gilpatrick, John D.; Kutac, Vincent G.; Martinez, Derwin

    2012-01-01

    The Los Alamos Neutron Science Center (LANSCE) deploys many cylindrical beam position and phase monitors (BPPM) throughout the linac to measure the beam central position, phase and bunched-beam current. Each monitor is calibrated and qualified prior to installation to insure it meets LANSCE requirements. The BPPM wire mapping system is used to map the BPPM electrode offset, sensitivity and higher order coefficients. This system uses a three-axis motion table to position the wire antenna structure within the cavity, simulating the beam excitation of a BPPM at a fundamental frequency of 201.25 MHz. RF signal strength is measured and recorded for the four electrodes as the antenna position is updated. An effort is underway to extend the systems service to the LANSCE facility by replacing obsolete electronic hardware and taking advantage of software enhancements. This paper describes the upgraded wire positioning system's new hardware and software capabilities including its revised antenna structure, motion control interface, RF measurement equipment and Labview software upgrades. The main purpose of the wire mapping system at LANSCE is to characterize the amplitude response versus beam central position of BPPMs before they are installed in the beam line. The wire mapping system is able to simulate a beam using a thin wire and measure the signal response as the wire position is varied within the BPPM aperture.

  14. Measurement of electron beam bunch phase length by rectangular cavities

    International Nuclear Information System (INIS)

    Afanas'ev, V.D.; Rudychev, V.G.; Ushakov, V.I.

    1976-01-01

    An analysis of a phase length of electron bunches with the help of crossed rectangular resonators with the Hsub(102) oscillation type has been made. It has been shown that the electron coordinates after the duplex resonator are described by an ellipse equation for a non-modulated beam. An influence of the initial energy spread upon the electron motion has been studied. It has been ascertained that energy modulation of the electron beam results in displacement of each electron with respect to the ellipse which is proportional to modulation energy, i.e. an error in determination of the phase length of an electron bunch is proportional to the beam energy spread. Relations have been obtained which enable to find genuine values of phases of the analyzed electrons with an accuracy up to linear multipliers

  15. Phase II beam lines at the National Synchrotron Light Source

    International Nuclear Information System (INIS)

    Thomlinson, W.

    1984-06-01

    The expansion of the National Synchrotron Light Source has been funded by the US Department of Energy. The Phase II program consists of both increased conventional facilities and six new beam lines. In this paper, an overview of the six beam lines which will be constructed during Phase II is presented. For five of the lines special radiation sources are necessary and the designs of four of the devices are complete. The relevant parameters of the insertion devices under construction and development are presented

  16. Phase changes caused by hyperventilation stress in spastic angina pectoris analyzed by first-pass radionuclide ventriculography

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jin; Takeda, Tohoru; Ajisaka, Ryuichi; Masuoka, Takeshi; Watanabe, Sigeyuki; Sato, Motohiro; Itai, Yuji [Tsukuba Univ., Ibaraki (Japan). Inst. of Clinical Medicine; Toyama, Hinako; Ishikawa, Nobuyoshi

    1999-02-01

    To understand the effect of hyperventilation (HV) stress in patients with spastic angina, left ventricular (LV) contraction was analyzed by quantitative phase analysis. The study was performed on 36 patients with spastic angina pectoris, including vasospastic angina pectoris (VspAP: 16 patients) and variant angina pectoris (VAP: 20 patients). First-pass radionuclide ventriculography (first-pass RNV) was performed at rest and after HV stress, and standard deviation of the LV phase distribution (SD) was analyzed. The SD was lower in patients with VspAP than in VAP(12.8{+-}1.4 degrees vs. 14.6{+-}2.2 degrees, p<0.005) at rest. After HV stress, the SD (HVSD) tended to increase in VspAP patients (62.5%), whereas the SD decreased in VAP patients (70%). Due to HV stress, the percentage change in SD (%SD) in VspAP patients was 8.9{+-}23.7% whereas that in VAP patients was -9.1{+-}17.3% (p<0.01). Moreover, phase histograms were divided into HVSD increase and HVSD decrease groups. The HVSD increase group had a decrease of HVEF, but the HVSD decrease group tended to have more decreased HVEF than the HVSD increase group. These results indicate that spastic angina pectoris patients show various responses to HV stress. The HVSD increase group might have additional myocardial ischemia due to regional coronary spasm. In contrast, in the HVSD decrease group severe LV dysfunction or diffuse wall motion abnormality might have been generated, and this caused a reduction in the SD value. Phase analysis would therefore add new information regarding electrocardiographically silent myocardial ischemia due to coronary spasm, and HV stress might increase sensitivity for the detection of abnormalities in quantitative phase analysis, especially in VspAP patients. (author)

  17. Phase changes caused by hyperventilation stress in spastic angina pectoris analyzed by first-pass radionuclide ventriculography

    International Nuclear Information System (INIS)

    Wu, Jin; Takeda, Tohoru; Ajisaka, Ryuichi; Masuoka, Takeshi; Watanabe, Sigeyuki; Sato, Motohiro; Itai, Yuji; Toyama, Hinako; Ishikawa, Nobuyoshi

    1999-01-01

    To understand the effect of hyperventilation (HV) stress in patients with spastic angina, left ventricular (LV) contraction was analyzed by quantitative phase analysis. The study was performed on 36 patients with spastic angina pectoris, including vasospastic angina pectoris (VspAP: 16 patients) and variant angina pectoris (VAP: 20 patients). First-pass radionuclide ventriculography (first-pass RNV) was performed at rest and after HV stress, and standard deviation of the LV phase distribution (SD) was analyzed. The SD was lower in patients with VspAP than in VAP(12.8±1.4 degrees vs. 14.6±2.2 degrees, p<0.005) at rest. After HV stress, the SD (HVSD) tended to increase in VspAP patients (62.5%), whereas the SD decreased in VAP patients (70%). Due to HV stress, the percentage change in SD (%SD) in VspAP patients was 8.9±23.7% whereas that in VAP patients was -9.1±17.3% (p<0.01). Moreover, phase histograms were divided into HVSD increase and HVSD decrease groups. The HVSD increase group had a decrease of HVEF, but the HVSD decrease group tended to have more decreased HVEF than the HVSD increase group. These results indicate that spastic angina pectoris patients show various responses to HV stress. The HVSD increase group might have additional myocardial ischemia due to regional coronary spasm. In contrast, in the HVSD decrease group severe LV dysfunction or diffuse wall motion abnormality might have been generated, and this caused a reduction in the SD value. Phase analysis would therefore add new information regarding electrocardiographically silent myocardial ischemia due to coronary spasm, and HV stress might increase sensitivity for the detection of abnormalities in quantitative phase analysis, especially in VspAP patients. (author)

  18. On Low-Pass Phase Noise Mitigation in OFDM System for mmWave Communications

    DEFF Research Database (Denmark)

    Chen, Xiaoming; Fan, Wei; Zhang, Anxue

    2017-01-01

    A phase noise (PN) mitigation scheme was proposed for orthogonal frequency division multiplexing (OFDM) in a previous work. The proposed scheme does not require detailed knowledge of PN statistics and can eectively compensate the PN with sucient number of unknowns. In this paper, we analyze....... It is also shown that the PN spectral shape of the phase-lockedloop (PLL) based oscillator also aects the PN mitigation and that a larger PN may not necessarily degrade the performance of the OFDM system with PN mitigation. Simulations with realistic millimeter-wave (mmWave) PN and channel models...

  19. Exploring the Nuclear Phase Diagram with Beam Energy Scans

    International Nuclear Information System (INIS)

    Horvat, Stephen

    2017-01-01

    The nuclear phase diagram is mapped using beam energy scans of relativistic heavy-ion collisions. This mapping is possible because different collision energies develop along different trajectories through the phase diagram. High energy collisions will evolve though a crossover phase transition according to lattice QCD, but lower collision energies may traverse a first order phase transition. There are hints for this first order phase transition and its critical endpoint, but further measurements and theoretical guidance is needed. In addition to mapping the phase transition, beam energy scans allow us to see if we can turn off the signatures of deconfinement. If an observable is a real signature for the formation of the deconfined state called quark-gluon plasma, then it should turn off at sufficiently low collision energies. In this summary talk I will show the current state of the field using beam energy scan results from RHIC and SPS, I will show where precise theoretical guidance is needed for understanding recent measurements, and I will motivate the need for more data and new measurements from FAIR, NICA, RHIC, and the SPS. (paper)

  20. Beam dynamics of alternating-phase-focused linac

    CERN Document Server

    Iwata, Y; Kapin, V

    2004-01-01

    A simple method to find an array of synchronous phases for alternating-phase-focused (APF) linacs is presented. The phase array is described with a smooth function having free parameters. With a set of the parameters, a simulation on the beam dynamics was made and distributions of the six-dimensional phase spaces were calculated for each set of the parameters. The parameters were varied, and numbers of the simulations have been performed. An optimum set of the parameters were determined so that the simulations of the beam dynamics yield large acceptances and small emittances of the extracted beams. Since the APF linac can provide both axial and radial stability of beams just with the rf acceleration-field, no additional focusing element inside of drift tubes are necessary. Comparing with conventional linacs having focusing elements, it has advantage in construction and operation costs as well as its acceleration rate. Therefore, the APF linacs would be suited for an injector of medical synchrotrons. A practic...

  1. Bunching and phase focusing of laser generated proton beams

    Energy Technology Data Exchange (ETDEWEB)

    Schumacher, Dennis; Hofmann, Ingo; Blazevic, Abel; Deppert, Oliver [GSI Helmholtzzentrum fuer Schwerionenforschung (Germany); Busold, Simon; Roth, Markus; Boine-Frankenheim, Oliver [TU Darmstadt (Germany); Brabetz, Christian [Universitaet Frankfurt, Frankfurt am Main (Germany); Zielbauer, Bernhard [HI Jena (Germany); Collaboration: LIGHT-Collaboration

    2013-07-01

    Laser accelerated proton beams can reach very high intensities and very low emittances. Therefore they are suitable as ion sources for many applications. One is the coupling into common ion accelerator structures to replace pre accelerators that are used so far. The LIGHT (Laser Ion Generation, Handling and Transport) collaboration has been founded to develop ion optics and targets and optimize laser parameter to make this coupling most efficient. In a first step a short pulse beam line for the PHELIX-laser at GSI to the experiment site Z6 has been build in order to laser accelerate protons here. In a second step a pulsed solenoid has been established to collimate the divergent ion beam. In a third step this collimated beam will be coupled into a bunching unit, which consists of a spiral resonator with three gaps which leads to an overall acceleration voltage of 1 MV. With this cavity it is not only possible to avoid the broadening of the pulse, but also to phase focus it. This talk presents also the progress towards the operation of the spiral resonator as buncher for a laser accelerated ion beam e.g. simulations, tests and performance data and shows the next steps of the beam shaping efforts.

  2. Single beam Fourier transform digital holographic quantitative phase microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Anand, A., E-mail: arun-nair-in@yahoo.com; Chhaniwal, V. K.; Mahajan, S.; Trivedi, V. [Optics Laboratory, Applied Physics Department, Faculty of Technology and Engineering, M.S. University of Baroda, Vadodara 390001 (India); Faridian, A.; Pedrini, G.; Osten, W. [Institut für Technische Optik, Universität Stuttgart, Pfaffenwaldring 9, 70569 Stuttgart (Germany); Dubey, S. K. [Siemens Technology and Services Pvt. Ltd, Corporate Technology—Research and Technology Centre, Bangalore 560100 (India); Javidi, B. [Department of Electrical and Computer Engineering, U-4157, University of Connecticut, Storrs, Connecticut 06269-2157 (United States)

    2014-03-10

    Quantitative phase contrast microscopy reveals thickness or height information of a biological or technical micro-object under investigation. The information obtained from this process provides a means to study their dynamics. Digital holographic (DH) microscopy is one of the most used, state of the art single-shot quantitative techniques for three dimensional imaging of living cells. Conventional off axis DH microscopy directly provides phase contrast images of the objects. However, this process requires two separate beams and their ratio adjustment for high contrast interference fringes. Also the use of two separate beams may make the system more vulnerable to vibrations. Single beam techniques can overcome these hurdles while remaining compact as well. Here, we describe the development of a single beam DH microscope providing whole field imaging of micro-objects. A hologram of the magnified object projected on to a diffuser co-located with a pinhole is recorded with the use of a commercially available diode laser and an arrayed sensor. A Fourier transform of the recorded hologram directly yields the complex amplitude at the image plane. The method proposed was investigated using various phase objects. It was also used to image the dynamics of human red blood cells in which sub-micrometer level thickness variation were measurable.

  3. Thermoacoustic focusing lens by symmetric Airy beams with phase manipulations

    Science.gov (United States)

    Liu, Chen; Xia, Jian-Ping; Sun, Hong-Xiang; Yuan, Shou-Qi

    2017-12-01

    We report the realization of broadband acoustic focusing lenses based on two symmetric thermoacoustic phased arrays of Airy beams, in which the units of thermoacoustic phase control are designed by employing air with different temperatures surrounded by rigid insulated boundaries and thermal insulation films. The phase delays of the transmitted and reflected units could cover a whole 2π interval, which arises from the change of the sound velocity of air induced by the variation of the temperature. Based on the units of phase control, we design the transmitted and reflected acoustic focusing lenses with two symmetric Airy beams, and verify the high self-healing focusing characteristic and the feasibility of the thermal insulation films. Besides, the influences of the bending angle of the Airy beam on the focusing performance are discussed in detail. The proposed acoustic lens has advantages of broad bandwidth (about 4.8 kHz), high focusing performance, self-healing feature, and simple structure, which enable it to provide more schemes for acoustic focusing. It has excellent potential applications in acoustic devices.

  4. Travelling Wave Solutions to Stretched Beam's Equation: Phase Portraits Survey

    International Nuclear Information System (INIS)

    Betchewe, Gambo; Victor, Kuetche Kamgang; Thomas, Bouetou Bouetou; Kofane, Timoleon Crepin

    2011-01-01

    In this paper, following the phase portraits analysis, we investigate the integrability of a system which physically describes the transverse oscillation of an elastic beam under end-thrust. As a result, we find that this system actually comprises two families of travelling waves: the sub- and super-sonic periodic waves of positive- and negative-definite velocities, respectively, and the localized sub-sonic loop-shaped waves of positive-definite velocity. Expressing the energy-like of this system while depicting its phase portrait dynamics, we show that these multivalued localized travelling waves appear as the boundary solutions to which the periodic travelling waves tend asymptotically. (general)

  5. Particle beam digital phase control system for COSY

    International Nuclear Information System (INIS)

    Schnase, A.

    1994-02-01

    Particle accelerators require that the orbit of the charged particles in the vacuum chamber is controlled to fulfil narrow limits. This is done by magnetic deflection systems and exactly adjusted rf-acceleration. Up to now the necessary control-functions were realised with analogue parts. This work describes a digital phase control system that works in real time and is used with the proton accelerator COSY. The physical design of the accelerator sets the accuracy-specifications of the revolution frequency (<1 Hz in the whole range from 400 kHz to 1.6 MHz), the phase-difference (<0.01 ), the signal-to-noise-ratio (<-60 dBc) and the update rate (<1 μs) of the parameters. In a typical operation the beam is first bunched and synchronised to the reference oscillator. After that the beam influences the rf-system with the help of charge detectors and now the rf-systems will be synchronised with the bunched beam. This control-loop is modelled and simulated with PSPICE. (orig.)

  6. Secondary beam line phase space measurement and modeling at LAMPF

    International Nuclear Information System (INIS)

    Floyd, R.; Harrison, J.; Macek, R.; Sanders, G.

    1979-01-01

    Hardware and software have been developed for precision on-line measurement and fitting of secondary beam line phase space parameters. A system consisting of three MWPC planes for measuring particle trajectories, in coincidence with a time-of-flight telescope and a range telescope for particle identification, has been interfaced to a computer. Software has been developed for on-line track reconstruction, application of experimental cuts, and fitting of two-dimensional phase space ellipses for each particle species. The measured distributions have been found to agree well with the predictions of the Monte Carlo program DECAY TURTLE. The fitted phase space ellipses are a useful input to optimization routines, such as TRANSPORT, used to search for superior tunes. Application of this system to the LAMPF Stopped Muon Channel is described

  7. Chemically Induced Phase Transformation in Austenite by Focused Ion Beam

    Science.gov (United States)

    Basa, Adina; Thaulow, Christian; Barnoush, Afrooz

    2014-03-01

    A highly stable austenite phase in a super duplex stainless steel was subjected to a combination of different gallium ion doses at different acceleration voltages. It was shown that contrary to what is expected, an austenite to ferrite phase transformation occurred within the focused ion beam (FIB) milled regions. Chemical analysis of the FIB milled region proved that the gallium implantation preceded the FIB milling. High resolution electron backscatter diffraction analysis also showed that the phase transformation was not followed by the typical shear and plastic deformation expected from the martensitic transformation. On the basis of these observations, it was concluded that the change in the chemical composition of the austenite and the local increase in gallium, which is a ferrite stabilizer, results in the local selective transformation of austenite to ferrite.

  8. Tailoring phase-space in neutron beam extraction

    Energy Technology Data Exchange (ETDEWEB)

    Weichselbaumer, S. [Heinz Maier-Leibnitz Zentrum und Physik-Department E21, Technische Universität München, Lichtenbergstr. 1, D-85748 Garching (Germany); Brandl, G. [Heinz Maier-Leibnitz Zentrum und Physik-Department E21, Technische Universität München, Lichtenbergstr. 1, D-85748 Garching (Germany); Physik-Department E21, Technische Universität München, James-Franck-Str. 1, D-85748 Garching (Germany); Georgii, R., E-mail: Robert.Georgii@frm2.tum.de [Heinz Maier-Leibnitz Zentrum und Physik-Department E21, Technische Universität München, Lichtenbergstr. 1, D-85748 Garching (Germany); Physik-Department E21, Technische Universität München, James-Franck-Str. 1, D-85748 Garching (Germany); Stahn, J. [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Panzner, T. [Material Science and Simulations, Neutrons and Muons, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Böni, P. [Physik-Department E21, Technische Universität München, James-Franck-Str. 1, D-85748 Garching (Germany)

    2015-09-01

    In view of the trend towards smaller samples and experiments under extreme conditions it is important to deliver small and homogeneous neutron beams to the sample area. For this purpose, elliptic and/or Montel mirrors are ideally suited as the phase space of the neutrons can be defined far away from the sample. Therefore, only the useful neutrons will arrive at the sample position leading to a very low background. We demonstrate the ease of designing neutron transport systems using simple numeric tools, which are verified using Monte-Carlo simulations that allow taking into account effects of gravity and finite beam size. It is shown that a significant part of the brilliance can be transferred from the moderator to the sample. Our results may have a serious impact on the design of instruments at spallation sources such as the European Spallation Source (ESS) in Lund, Sweden.

  9. Prospects for electron beam aberration correction using sculpted phase masks

    Energy Technology Data Exchange (ETDEWEB)

    Shiloh, Roy, E-mail: royshilo@post.tau.ac.il; Remez, Roei; Arie, Ady

    2016-04-15

    Technological advances in fabrication methods allowed the microscopy community to take incremental steps towards perfecting the electron microscope, and magnetic lens design in particular. Still, state of the art aberration-corrected microscopes are yet 20–30 times shy of the theoretical electron diffraction limit. Moreover, these microscopes consume significant physical space and are very expensive. Here, we show how a thin, sculpted membrane is used as a phase-mask to induce specific aberrations into an electron beam probe in a standard high resolution TEM. In particular, we experimentally demonstrate beam splitting, two-fold astigmatism, three-fold astigmatism, and spherical aberration. - Highlights: • Thin membranes can be used as aberration correctors in electron columns. • We demonstrate tilt, twofold-, threefold-astigmatism, and spherical aberrations. • Experimental and physical-optics simulation results are in good agreement. • Advantages in cost, size, nonmagnetism, and nearly-arbitrary correction.

  10. Geometric phase in a split-beam experiment measured with coupled neutron interference loops

    International Nuclear Information System (INIS)

    Hasegawa, Yuji; Zawisky, M.; Rauch, H.; Ioffe, A.

    1996-01-01

    A geometric phase factor is derived for a split-beam experiment as an example of cyclic evolutions. The geometric phase is given by one half of the solid angle independent of the spin of the beam. We observe this geometric phase with a two-loop neutron interferometer, where a reference beam can be added to the beam from one interference loop. All the experimental results show complete agreement with our theoretical treatment. (author)

  11. Development of SiC Nanoparticles and Second Phases Synergistically Reinforced Mg-Based Composites Processed by Multi-Pass Forging with Varying Temperatures

    Directory of Open Access Journals (Sweden)

    Kaibo Nie

    2018-01-01

    Full Text Available In this study, SiC nanoparticles were added into matrix alloy through a combination of semisolid stirring and ultrasonic vibration while dynamic precipitation of second phases was obtained through multi-pass forging with varying temperatures. During single-pass forging of the present composite, as the deformation temperature increased, the extent of recrystallization increased, and grains were refined due to the inhibition effect of the increasing amount of dispersed SiC nanoparticles. A small amount of twins within the SiC nanoparticle dense zone could be found while the precipitated phases of Mg17Al12 in long strips and deformation bands with high density dislocations were formed in the particle sparse zone after single-pass forging at 350 °C. This indicated that the particle sparse zone was mainly deformed by dislocation slip while the nanoparticle dense zone may have been deformed by twinning. The yield strength and ultimate tensile strength of the composites were gradually enhanced through increasing the single-pass forging temperature from 300 °C to 400 °C, which demonstrated that initial high forging temperature contributed to the improvement of the mechanical properties. During multi-pass forging with varying temperatures, the grain size of the composite was gradually decreased while the grain size distribution tended to be uniform with reducing the deformation temperature and extending the forging passes. In addition, the amount of precipitated second phases was significantly increased compared with that after multi-pass forging under a constant temperature. The improvement in the yield strength of the developed composite was related to grain refinement strengthening and Orowan strengthening resulting from synergistical effect of the externally applied SiC nanoparticles and internally precipitated second phases.

  12. The backward phase flow and FBI-transform-based Eulerian Gaussian beams for the Schroedinger equation

    International Nuclear Information System (INIS)

    Leung Shingyu; Qian Jianliang

    2010-01-01

    We propose the backward phase flow method to implement the Fourier-Bros-Iagolnitzer (FBI)-transform-based Eulerian Gaussian beam method for solving the Schroedinger equation in the semi-classical regime. The idea of Eulerian Gaussian beams has been first proposed in . In this paper we aim at two crucial computational issues of the Eulerian Gaussian beam method: how to carry out long-time beam propagation and how to compute beam ingredients rapidly in phase space. By virtue of the FBI transform, we address the first issue by introducing the reinitialization strategy into the Eulerian Gaussian beam framework. Essentially we reinitialize beam propagation by applying the FBI transform to wavefields at intermediate time steps when the beams become too wide. To address the second issue, inspired by the original phase flow method, we propose the backward phase flow method which allows us to compute beam ingredients rapidly. Numerical examples demonstrate the efficiency and accuracy of the proposed algorithms.

  13. Phase and synchronous detector theory as applied to beam position and intensity measurements

    International Nuclear Information System (INIS)

    Gilpatrick, J.D.

    1995-01-01

    A popular signal processing technique for beam position measurements uses the principle of amplitude-to-phase (AM/PM) conversion and phase detection. This technique processes position-sensitive beam-image-current probe-signals into output signals that are proportional to the beam's position. These same probe signals may be summed and processed in a different fashion to provide output signals that are proportional to the peak beam current which is typically referred to as beam intensity. This paper derives the transfer functions for the AM/PM beam position and peak beam current processors

  14. A Phase Space Monitoring of Injected Beam of J-PARC MR

    Science.gov (United States)

    Hatakeyama, Shuichiro; Toyama, Takeshi

    Beam power of J-PARC MR (30 GeV Proton Synchrotron Main Ring) has been improved since 2008 and now achieved over 200 kW for the user operation. A part of beam loss is localized at the beam injection phase so it is important to monitor the beam bunch behavior in the transverse direction. In this paper it is described the method how to measure the position and momentum for each injected beam bunch using Beam Position Monitors (BPMs). It is also mentioned some implementation of an operator's interface (OPI) to display the plots of injected and circulating beam bunches in phase space coordinate.

  15. 3D-printed phase waveplates for THz beam shaping

    Science.gov (United States)

    Gospodaric, J.; Kuzmenko, A.; Pimenov, Anna; Huber, C.; Suess, D.; Rotter, S.; Pimenov, A.

    2018-05-01

    The advancement of 3D-printing opens up a new way of constructing affordable custom terahertz (THz) components due to suitable printing resolution and THz transparency of polymer materials. We present a way of calculating, designing, and fabricating a THz waveplate that phase-modulates an incident THz beam (λ0 = 2.14 mm) in order to create a predefined intensity profile of the optical wavefront on a distant image plane. Our calculations were performed for two distinct target intensities with the use of a modified Gerchberg-Saxton algorithm. The resulting phase-modulating profiles were used to model the polylactide elements, which were printed out with a commercially available 3D-printer. The results were tested in a THz experimental setup equipped with a scanning option, and they showed good agreement with theoretical predictions.

  16. Highly integrated optical phased arrays: photonic integrated circuits for optical beam shaping and beam steering

    Science.gov (United States)

    Heck, Martijn J. R.

    2017-01-01

    Technologies for efficient generation and fast scanning of narrow free-space laser beams find major applications in three-dimensional (3D) imaging and mapping, like Lidar for remote sensing and navigation, and secure free-space optical communications. The ultimate goal for such a system is to reduce its size, weight, and power consumption, so that it can be mounted on, e.g. drones and autonomous cars. Moreover, beam scanning should ideally be done at video frame rates, something that is beyond the capabilities of current opto-mechanical systems. Photonic integrated circuit (PIC) technology holds the promise of achieving low-cost, compact, robust and energy-efficient complex optical systems. PICs integrate, for example, lasers, modulators, detectors, and filters on a single piece of semiconductor, typically silicon or indium phosphide, much like electronic integrated circuits. This technology is maturing fast, driven by high-bandwidth communications applications, and mature fabrication facilities. State-of-the-art commercial PICs integrate hundreds of elements, and the integration of thousands of elements has been shown in the laboratory. Over the last few years, there has been a considerable research effort to integrate beam steering systems on a PIC, and various beam steering demonstrators based on optical phased arrays have been realized. Arrays of up to thousands of coherent emitters, including their phase and amplitude control, have been integrated, and various applications have been explored. In this review paper, I will present an overview of the state of the art of this technology and its opportunities, illustrated by recent breakthroughs.

  17. Highly integrated optical phased arrays: photonic integrated circuits for optical beam shaping and beam steering

    Directory of Open Access Journals (Sweden)

    Heck Martijn J.R.

    2016-06-01

    Full Text Available Technologies for efficient generation and fast scanning of narrow free-space laser beams find major applications in three-dimensional (3D imaging and mapping, like Lidar for remote sensing and navigation, and secure free-space optical communications. The ultimate goal for such a system is to reduce its size, weight, and power consumption, so that it can be mounted on, e.g. drones and autonomous cars. Moreover, beam scanning should ideally be done at video frame rates, something that is beyond the capabilities of current opto-mechanical systems. Photonic integrated circuit (PIC technology holds the promise of achieving low-cost, compact, robust and energy-efficient complex optical systems. PICs integrate, for example, lasers, modulators, detectors, and filters on a single piece of semiconductor, typically silicon or indium phosphide, much like electronic integrated circuits. This technology is maturing fast, driven by high-bandwidth communications applications, and mature fabrication facilities. State-of-the-art commercial PICs integrate hundreds of elements, and the integration of thousands of elements has been shown in the laboratory. Over the last few years, there has been a considerable research effort to integrate beam steering systems on a PIC, and various beam steering demonstrators based on optical phased arrays have been realized. Arrays of up to thousands of coherent emitters, including their phase and amplitude control, have been integrated, and various applications have been explored. In this review paper, I will present an overview of the state of the art of this technology and its opportunities, illustrated by recent breakthroughs.

  18. Parametric Raman crystalline anti-Stokes laser at 503 nm with collinear beam interaction at tangential phase matching

    Science.gov (United States)

    Smetanin, S. N.; Jelínek, M.; Kubeček, V.

    2017-07-01

    Stimulated-Raman-scattering in crystals can be used for the single-pass frequency-conversion to the Stokes-shifted wavelengths. The anti-Stokes shift can also be achieved but the phase-matching condition has to be fulfilled because of the parametric four-wave mixing process. To widen the angular-tolerance of four-wave mixing and to obtain high-conversion-efficiency into the anti-Stokes, we developed a new scheme of the parametric Raman anti-Stokes laser at 503 nm with phase-matched collinear beam interaction of orthogonally-polarized Raman components in calcite oriented at the phase-matched angle under 532 nm 20 ps laser excitation. The excitation laser beam was split into two orthogonally-polarized components entering the calcite at the certain incidence angles to fulfill the nearly collinear phase-matching and also to compensate walk-off of extraordinary waves for collinear beam interaction. The phase matching of parametric Raman interaction is tangential and insensitive to the angular mismatch if the Poynting vectors of the biharmonic pump and parametrically generated (anti-Stokes) waves are collinear. For the first time it allows to achieve experimentally the highest conversion efficiency into the anti-Stokes wave (503 nm) up to 30% from the probe wave and up to 3.5% from both pump and probe waves in the single-pass picosecond parametric calcite Raman laser. The highest anti-Stokes pulse energy was 1.4 μJ.

  19. A model to determine the initial phase space of a clinical electron beam from measured beam data.

    NARCIS (Netherlands)

    Janssen, J.J.M.; Korevaar, E.W.; Battum, L.J. van; Storchi, P.R.; Huizenga, H.

    2001-01-01

    Advanced electron beam dose calculation models for radiation oncology require as input an initial phase space (IPS) that describes a clinical electron beam. The IPS is a distribution in position, energy and direction of electrons and photons in a plane in front of the patient. A method is presented

  20. Generation of phase singularity through diffracting a plane or Gaussian beam by a spiral phase plate.

    Science.gov (United States)

    Kotlyar, Victor V; Almazov, Anton A; Khonina, Svetlana N; Soifer, Victor A; Elfstrom, Henna; Turunen, Jari

    2005-05-01

    We deduce and study an analytical expression for Fresnel diffraction of a plane wave by a spiral phase plate (SPP) that imparts an arbitrary-order phase singularity on the light field. Estimates for the optical vortex radius that depends on the singularity's integer order n (also termed topological charge, or order of the dislocation) have been derived. The near-zero vortex intensity is shown to be proportional to rho2n, where p is the radial coordinate. Also, an analytical expression for Fresnel diffraction of the Gaussian beam by a SPP with nth-order singularity is analyzed. The far-field intensity distribution is derived. The radius of maximal intensity is shown to depend on the singularity number. The behavior of the Gaussian beam intensity after a SPP with second-order singularity (n = 2) is studied in more detail. The parameters of the light beams generated numerically with the Fresnel transform and via analytical formulas are in good agreement. In addition, the light fields with first- and second-order singularities were generated by a 32-level SPP fabricated on the resist by use of the electron-beam lithography technique.

  1. Laser-beam apodization with a graded random phase window

    Energy Technology Data Exchange (ETDEWEB)

    Haas, R.A.; Summers, M.A.; Linford, G.J.

    1986-10-01

    Experiments and analysis indicate that graded random phase modulation can be usesd to apodize a laser beam. In the case of an obscuration or a hard edge it can prevent the formation of Fresnel-diffraction ripples. For example, here the interaction of a 1-..mu..m-wavelength laser beam with a central obscuration of half-width a -- 100 ..mu..m is studied theoretically. It is found that if the exit surface of a window, placed immediately downstream of the obstacle, is randomly modulated with a Gaussian amplitude transverse correlation length l -- 50..mu..m and a mean-square amplitude that decreases exponentially from a peak height of --1..mu..m/sup 2/ away from the center of the obscuration with transverse scale length L -- 500 ..mu..m, then the Fresenel-diffraction ripples normally produced by the obscuration are elimated. The scaling of these results is also discussed. The calculations are in general agreement with experimental results.

  2. Laser-beam apodization with a graded random phase window

    International Nuclear Information System (INIS)

    Haas, R.A.; Summers, M.A.; Linford, G.J.

    1986-01-01

    Experiments and analysis indicate that graded random phase modulation can be usesd to apodize a laser beam. In the case of an obscuration or a hard edge it can prevent the formation of Fresnel-diffraction ripples. For example, here the interaction of a 1-μm-wavelength laser beam with a central obscuration of half-width a -- 100 μm is studied theoretically. It is found that if the exit surface of a window, placed immediately downstream of the obstacle, is randomly modulated with a Gaussian amplitude transverse correlation length l -- 50μm and a mean-square amplitude that decreases exponentially from a peak height of --1μm 2 away from the center of the obscuration with transverse scale length L -- 500 μm, then the Fresenel-diffraction ripples normally produced by the obscuration are elimated. The scaling of these results is also discussed. The calculations are in general agreement with experimental results

  3. Chaotic phase oscillation of a proton beam in a synchrotron

    International Nuclear Information System (INIS)

    Li Fei; Hai Wenhua; Ren Zhongzhou; Shu Weixing

    2006-01-01

    We investigate the chaotic phase oscillation of a proton beam in a cooler synchrotron. By using direct perturbation method, we construct the general solution of the 1st-order equation. It is demonstrated that the general solution is bounded under some initial and parameter conditions. From these conditions, we get a Melnikov function which predicts the existence of Smale-horseshoe chaos iff it has simple zeros. Our result under the 1st-order approximation is in good agreement with that in [H. Huang et al., Phys. Rev. E 48 (1993) 4678]. When the perturbation method is not suitable for the system, numerical simulation shows the system may present transient chaos before it goes into periodical oscillation; changing the damping parameter can result in or suppress stationary chaos

  4. Pbar Beam Stacking in the Recycler by Longitudinal Phase-space Coating

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, C. M. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2013-08-06

    Barrier rf buckets have brought about new challenges in longitudinal beam dynamics of charged particle beams in synchrotrons and at the same time led to many new remarkable prospects in beam handling. In this paper, I describe a novel beam stacking scheme for synchrotrons using barrier buckets without any emittance dilution to the beam. First I discuss the general principle of the method, called longitudinal phase-space coating. Multi-particle beam dynamics simulations of the scheme applied to the Recycler, convincingly validates the concepts and feasibility of the method. Then I demonstrate the technique experimentally in the Recycler and also use it in operation. A spin-off of this scheme is its usefulness in mapping the incoherent synchrotron tune spectrum of the beam particles in barrier buckets and producing a clean hollow beam in longitudinal phase space. Both of which are described here in detail with illustrations. The beam stacking scheme presented here is the first of its kind.

  5. Electron-beam synthesis of fuel in the gas phase

    International Nuclear Information System (INIS)

    Ponomarev, A.V.; Holodkova, E.M.; Ershov, B.G.

    2011-01-01

    Complete text of publication follows. Tendencies of world development focus attention on a vegetative biomass as on the major raw resource for future chemistry and a fuel industry. The significant potential for perfection of biomass conversion processes is concentrated in the field of radiation-chemical methods. Both the mode of post-radiation distillation and mode of electron-beam distillation of biomass have been investigated as well as the mode of gas-phase synthesis of liquid engine fuel from of biomass distillation products. Synergistic action of radiation and temperature has been analyzed at use of the accelerated electron beams allowing to combine radiolysis with effective radiation heating of a material without use of additional heaters. At dose rate above 1 kGy/s the electron-beam irradiation results in intensive decomposition of a biomass and evaporation of formed fragments with obtaining of a liquid condensate (∼ 60 wt%), CO 2 and Co gases (13-18 wt%) and charcoal in the residue. Biomass distillation at radiation heating allows to increase almost three times an organic liquid yield in comparison with pyrolysis. The majority of liquid products from cellulose is represented by the furan derivatives considered among the very perspective components for alternative engine fuels. Distilled-off gases and vapors are diluted with gaseous C 1 -C 5 alkanes and again are exposed to an irradiation to produce liquid fuel from a biomass. This transformation is based on a method of electron-beam circulation conversion of gaseous C 1 -C 5 alkanes (Ponomarev, A.V., Radiat. Phys. Chem., 78, 48, 2009) which consists in formation and removal of liquid products with high degree of carbon skeleton branching. The isomers ratio in a liquid may be controlled by means of change of an irradiation condition and initial gas composition. The irradiation of gaseous alkanes together with vaporous products of biomass destruction allows to synthesize the fuel enriched by conventional

  6. Application of a transverse phase-space measurement technique for high-brightness, H- beams to the GTA H- beam

    International Nuclear Information System (INIS)

    Johnson, K.F.; Garcia, R.C.; Rusthoi, D.P.; Sander, O.R.; Sandoval, D.P.; Shinas, M.A.; Smith, M.; Yuan, V.W.; Connolly, R.C.

    1995-01-01

    The Ground Test Accelerator (GTA) had the objective Of Producing a high-brightness, high-current H-beam. The major components were a 35 keV injector, a Radio Frequency Quadrupole (RFQ), an intertank matching section (IMS), and a drift tube linac (DTL), consisting of 10 modules. A technique for measuring the transverse phase-space of high-power density beams has been developed and tested. This diagnostic has been applied to the GTA H-beam. Experimental results are compared to the slit and collector technique for transverse phase-space measurements and to simulations

  7. Using a short-pulse diffraction-limited laser beam to probe filamentation of a random phase plate smoothed beam

    International Nuclear Information System (INIS)

    Kline, J. L.; Montgomery, D. S.; Flippo, K. A.; Johnson, R. P.; Rose, H. A.; Shimada, T.; Williams, E. A.

    2008-01-01

    A short pulse (few picoseconds) laser probe provides high temporal resolution measurements to elucidate details of fast dynamic phenomena not observable with typical longer laser pulse probes and gated diagnostics. Such a short pulse laser probe (SPLP) has been used to measure filamentation of a random phase plate (RPP) smoothed laser beam in a gas-jet plasma. The plasma index of refraction due to driven density and temperature fluctuations by the RPP beam perturbs the phase front of a SPLP propagating at a 90 deg. angle with respect to the RPP interaction beam. The density and temperature fluctuations are quasistatic on the time scale of the SPLP (∼2 ps). The transmitted near-field intensity distribution from the SPLP provides a measure of the phase front perturbation. At low plasma densities, the transmitted intensity pattern is asymmetric with striations across the entire probe beam in the direction of the RPP smoothed beam. As the plasma density increases, the striations break up into smaller sizes along the direction of the RPP beam propagation. The breakup of the intensity pattern is consistent with self-focusing of the RPP smoothed interaction beam. Simulations of the experiment using the wave propagation code, PF3D, are in qualitative agreement demonstrating that the asymmetric striations can be attributed to the RPP driven density fluctuations. Quantification of the beam breakup measured by the transmitted SPLP could lead to a new method for measuring self-focusing of lasers in underdense plasmas.

  8. Using a short-pulse diffraction-limited laser beam to probe filamentation of a random phase plate smoothed beam.

    Science.gov (United States)

    Kline, J L; Montgomery, D S; Flippo, K A; Johnson, R P; Rose, H A; Shimada, T; Williams, E A

    2008-10-01

    A short pulse (few picoseconds) laser probe provides high temporal resolution measurements to elucidate details of fast dynamic phenomena not observable with typical longer laser pulse probes and gated diagnostics. Such a short pulse laser probe (SPLP) has been used to measure filamentation of a random phase plate (RPP) smoothed laser beam in a gas-jet plasma. The plasma index of refraction due to driven density and temperature fluctuations by the RPP beam perturbs the phase front of a SPLP propagating at a 90 degree angle with respect to the RPP interaction beam. The density and temperature fluctuations are quasistatic on the time scale of the SPLP (approximately 2 ps). The transmitted near-field intensity distribution from the SPLP provides a measure of the phase front perturbation. At low plasma densities, the transmitted intensity pattern is asymmetric with striations across the entire probe beam in the direction of the RPP smoothed beam. As the plasma density increases, the striations break up into smaller sizes along the direction of the RPP beam propagation. The breakup of the intensity pattern is consistent with self-focusing of the RPP smoothed interaction beam. Simulations of the experiment using the wave propagation code, PF3D, are in qualitative agreement demonstrating that the asymmetric striations can be attributed to the RPP driven density fluctuations. Quantification of the beam breakup measured by the transmitted SPLP could lead to a new method for measuring self-focusing of lasers in underdense plasmas.

  9. Creating Ruddlesden-Popper phases by hybrid molecular beam epitaxy

    International Nuclear Information System (INIS)

    Haislmaier, Ryan C.; Stone, Greg; Alem, Nasim; Engel-Herbert, Roman

    2016-01-01

    The synthesis of a 50 unit cell thick n = 4 Sr_n_+_1Ti_nO_3_n_+_1 (Sr_5Ti_4O_1_3) Ruddlesden-Popper (RP) phase film is demonstrated by sequentially depositing SrO and TiO_2 layers in an alternating fashion using hybrid molecular beam epitaxy (MBE), where Ti was supplied using titanium tetraisopropoxide (TTIP). A detailed calibration procedure is outlined for determining the shuttering times to deposit SrO and TiO_2 layers with precise monolayer doses using in-situ reflection high energy electron diffraction (RHEED) as feedback. Using optimized Sr and TTIP shuttering times, a fully automated growth of the n = 4 RP phase was carried out over a period of >4.5 h. Very stable RHEED intensity oscillations were observed over the entire growth period. The structural characterization by X-ray diffraction and high resolution transmission electron microscopy revealed that a constant periodicity of four SrTiO_3 perovskite unit cell blocks separating the double SrO rocksalt layer was maintained throughout the entire film thickness with a very little amount of planar faults oriented perpendicular to the growth front direction. These results illustrate that hybrid MBE is capable of layer-by-layer growth with atomic level precision and excellent flux stability.

  10. Creating Ruddlesden-Popper phases by hybrid molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Haislmaier, Ryan C.; Stone, Greg; Alem, Nasim; Engel-Herbert, Roman, E-mail: rue2@psu.edu [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2016-07-25

    The synthesis of a 50 unit cell thick n = 4 Sr{sub n+1}Ti{sub n}O{sub 3n+1} (Sr{sub 5}Ti{sub 4}O{sub 13}) Ruddlesden-Popper (RP) phase film is demonstrated by sequentially depositing SrO and TiO{sub 2} layers in an alternating fashion using hybrid molecular beam epitaxy (MBE), where Ti was supplied using titanium tetraisopropoxide (TTIP). A detailed calibration procedure is outlined for determining the shuttering times to deposit SrO and TiO{sub 2} layers with precise monolayer doses using in-situ reflection high energy electron diffraction (RHEED) as feedback. Using optimized Sr and TTIP shuttering times, a fully automated growth of the n = 4 RP phase was carried out over a period of >4.5 h. Very stable RHEED intensity oscillations were observed over the entire growth period. The structural characterization by X-ray diffraction and high resolution transmission electron microscopy revealed that a constant periodicity of four SrTiO{sub 3} perovskite unit cell blocks separating the double SrO rocksalt layer was maintained throughout the entire film thickness with a very little amount of planar faults oriented perpendicular to the growth front direction. These results illustrate that hybrid MBE is capable of layer-by-layer growth with atomic level precision and excellent flux stability.

  11. Method of phase space beam dilution utilizing bounded chaos generated by rf phase modulation

    Directory of Open Access Journals (Sweden)

    Alfonse N. Pham

    2015-12-01

    Full Text Available This paper explores the physics of chaos in a localized phase-space region produced by rf phase modulation applied to a double rf system. The study can be exploited to produce rapid particle bunch broadening exhibiting longitudinal particle distribution uniformity. Hamiltonian models and particle-tracking simulations are introduced to understand the mechanism and applicability of controlled particle diffusion. When phase modulation is applied to the double rf system, regions of localized chaos are produced through the disruption and overlapping of parametric resonant islands and configured to be bounded by well-behaved invariant tori to prevent particle loss. The condition of chaoticity and the degree of particle dilution can be controlled by the rf parameters. The method has applications in alleviating adverse space-charge effects in high-intensity beams, particle bunch distribution uniformization, and industrial radiation-effects experiments.

  12. Radial modes in phase-only twisted light beams

    CSIR Research Space (South Africa)

    Sephton, Bereneice C

    2017-08-01

    Full Text Available Beams carrying orbital angular momentum (OAM) are ubiquitous in many experiments carried out today and cover a wide range of research, from surface microstructure processing to optical tweezers and communications. It follows that these beams are a...

  13. Single-pass, efficient type-I phase-matched frequency doubling of high-power ultrashort-pulse Yb-fiber laser using LiB_3O_5

    Science.gov (United States)

    Shukla, Mukesh Kumar; Kumar, Samir; Das, Ritwick

    2016-05-01

    We report 48 % efficient single-pass second harmonic generation of high-power ultrashort-pulse ({≈ }250 fs) Yb-fiber laser by utilizing type-I phase matching in LiB_3O_5 (LBO) crystal. The choice of LBO among other borate crystals for high-power frequency doubling is essentially motivated by large thermal conductivity, low birefringence and weak group velocity dispersion. By optimally focussing the beam in a 4-mm-long LBO crystal, we have generated about 2.3 W of average power at 532 nm using 4.8 W of available pump power at 1064 nm. The ultrashort green pulses were found out to be near-transform limited sech^2 pulses with a pulse width of Δ τ ≈ 150 fs and being delivered at 78 MHz repetition rate. Due to appreciably low spatial walk-off angle for LBO ({≈ }0.4°), we obtain M^2beam which signifies marginal distortion in comparison with the pump beam (M^2<1.15). We also discuss the impact of third-order optical nonlinearity of the LBO crystal on the generated ultrashort SH pulses.

  14. Multi-beam synchronous measurement based on PSD phase detection using frequency-domain multiplexing

    Science.gov (United States)

    Duan, Ying; Qin, Lan; Xue, Lian; Xi, Feng; Mao, Jiubing

    2013-10-01

    According to the principle of centroid measurement, position-sensitive detectors (PSD) are commonly used for micro displacement detection. However, single-beam detection method cannot satisfy such tasks as multi-dimension position measurement, three dimension vision reconstruction, and robot precision positioning, which require synchronous measurement of multiple light beams. Consequently, we designed PSD phase detection method using frequency-domain multiplexing for synchronous detection of multiple modulated light beams. Compared to previous PSD amplitude detection method, the phase detection method using FDM has advantages of simplified measuring system, low cost, high capability of resistance to light interference as well as improved resolution. The feasibility of multi-beam synchronous measurement based on PSD phase detection using FDM was validated by multi-beam measuring experiments. The maximum non-linearity error of the multi-beam synchronous measurement is 6.62%.

  15. Vortex phase-induced changes of the statistical properties of a partially coherent radially polarized beam.

    Science.gov (United States)

    Guo, Lina; Chen, Yahong; Liu, Xianlong; Liu, Lin; Cai, Yangjian

    2016-06-27

    Partially coherent radially polarized (PCRP) beam was introduced and generated in recent years. In this paper, we investigate the statistical properties of a PCRP beam embedded with a vortex phase (i.e., PCRP vortex beam). We derive the analytical formula for the cross-spectral density matrix of a PCRP vortex beam propagating through a paraxial ABCD optical system and analyze the statistical properties of a PCRP vortex beam focused by a thin lens. It is found that the statistical properties of a PCRP vortex beam on propagation are much different from those of a PCRP beam. The vortex phase induces not only the rotation of the beam spot, but also the changes of the beam shape, the degree of polarization and the state of polarization. We also find that the vortex phase plays a role of resisting the coherence-induced degradation of the intensity distribution and the coherence-induced depolarization. Furthermore, we report experimental generation of a PCRP vortex beam for the first time. Our results will be useful for trapping and rotating particles, free-space optical communications and detection of phase object.

  16. Fundamentals of particle beam dynamics and phase space

    International Nuclear Information System (INIS)

    Weng, W.T.; Mane, S.R.

    1991-01-01

    This report discusses the following topics on synchrotron accelerators: Transverse motion---betatron oscillations; machine lattice; representation of a particle beam; and longitudinal motion---synchrotron oscillations

  17. Automatic Phase Calibration for RF Cavities using Beam-Loading Signals

    Energy Technology Data Exchange (ETDEWEB)

    Edelen, J. P. [Fermilab; Chase, B. E. [Fermilab

    2017-10-01

    Precise calibration of the cavity phase signals is necessary for the operation of any particle accelerator. For many systems this requires human in the loop adjustments based on measurements of the beam parameters downstream. Some recent work has developed a scheme for the calibration of the cavity phase using beam measurements and beam-loading however this scheme is still a multi-step process that requires heavy automation or human in the loop. In this paper we analyze a new scheme that uses only RF signals reacting to beam-loading to calculate the phase of the beam relative to the cavity. This technique could be used in slow control loops to provide real-time adjustment of the cavity phase calibration without human intervention thereby increasing the stability and reliability of the accelerator.

  18. A line scanned light-sheet microscope with phase shaped self-reconstructing beams.

    Science.gov (United States)

    Fahrbach, Florian O; Rohrbach, Alexander

    2010-11-08

    We recently demonstrated that Microscopy with Self-Reconstructing Beams (MISERB) increases both image quality and penetration depth of illumination beams in strongly scattering media. Based on the concept of line scanned light-sheet microscopy, we present an add-on module to a standard inverted microscope using a scanned beam that is shaped in phase and amplitude by a spatial light modulator. We explain technical details of the setup as well as of the holograms for the creation, positioning and scaling of static light-sheets, Gaussian beams and Bessel beams. The comparison of images from identical sample areas illuminated by different beams allows a precise assessment of the interconnection between beam shape and image quality. The superior propagation ability of Bessel beams through inhomogeneous media is demonstrated by measurements on various scattering media.

  19. Propagation of a radial phased-locked Lorentz beam array in turbulent atmosphere.

    Science.gov (United States)

    Zhou, Guoquan

    2011-11-21

    A radial phased-locked (PL) Lorentz beam array provides an appropriate theoretical model to describe a coherent diode laser array, which is an efficient radiation source for high-power beaming use. The propagation of a radial PL Lorentz beam array in turbulent atmosphere is investigated. Based on the extended Huygens-Fresnel integral and some mathematical techniques, analytical formulae for the average intensity and the effective beam size of a radial PL Lorentz beam array are derived in turbulent atmosphere. The average intensity distribution and the spreading properties of a radial PL Lorentz beam array in turbulent atmosphere are numerically calculated. The influences of the beam parameters and the structure constant of the atmospheric turbulence on the propagation of a radial PL Lorentz beam array in turbulent atmosphere are discussed in detail. © 2011 Optical Society of America

  20. MESSENGER Spacecraft Phase Scintillation due to Plasma ductting effect on RF beam propagation at Superior Solar Conjunction

    Science.gov (United States)

    Mosavi, N.; Sequeira, H.; Copeland, D.; Menyuk, C.

    2017-12-01

    We investigate the evolution of a radio frequency (RF) X-band signal as it propagates through the solar corona turbulence in superior solar conjunction at low Sun-Earth-Probe (SEP) angles.Data that was obtained during several MESSENGER (MErcury Surface, Space ENivornment, GEochmeisty, and Ranging) conjunctions reveal a short-term and long-term effect. Amplitude scintillation is evident on a short time scale. Phase scintillations are stronger, but occur over a longer time scale. We examine different possible phenomena in the solar plasma that could be the source of the different time scales of the amplitude and phase scintillations. We propose a theoretical model in which the amplitude scintillations are due to local fluctuations of the index of refraction that scatter the RF signal. These rapidly varying fluctuations randomly attenuate the signal without affecting its phase. By contrast, we propose a model in which phase fluctuations are due to long ducts in the solar plasma, streaming from the sun, that trap some parts of the RF signal. These ducts act as waveguides, changing the phase velocity of the RF beam as it travels a zigzag path inside a duct. When the radiated wave exits from a duct, its phase is changed with respect to the signal that did not pass through the duct, which can lead to destructive interference and carrier suppression. The trapping of the wave is random in nature and can be either a fast or slow process. The predictions of this model are consistent with observations.

  1. Hermite-Gaussian beams with self-forming spiral phase distribution

    Science.gov (United States)

    Zinchik, Alexander A.; Muzychenko, Yana B.

    2014-05-01

    Spiral laser beams is a family of laser beams that preserve the structural stability up to scale and rotate with the propagation. Properties of spiral beams are of practical interest for laser technology, medicine and biotechnology. Researchers use a spiral beams for movement and manipulation of microparticles. Spiral beams have a complicated phase distribution in cross section. This paper describes the results of analytical and computer simulation of Hermite-Gaussian beams with self-forming spiral phase distribution. In the simulation used a laser beam consisting of the sum of the two modes HG TEMnm and TEMn1m1. The coefficients n1, n, m1, m were varied. Additional phase depending from the coefficients n, m, m1, n1 imposed on the resulting beam. As a result, formed the Hermite Gaussian beam phase distribution which takes the form of a spiral in the process of distribution. For modeling was used VirtualLab 5.0 (manufacturer LightTrans GmbH).

  2. Impact of tissue atrophy on high-pass filtered MRI signal phase-based assessment in large-scale group-comparison studies: A simulation study

    Science.gov (United States)

    Schweser, Ferdinand; Dwyer, Michael G.; Deistung, Andreas; Reichenbach, Jürgen R.; Zivadinov, Robert

    2013-10-01

    The assessment of abnormal accumulation of tissue iron in the basal ganglia nuclei and in white matter plaques using the gradient echo magnetic resonance signal phase has become a research focus in many neurodegenerative diseases such as multiple sclerosis or Parkinson’s disease. A common and natural approach is to calculate the mean high-pass-filtered phase of previously delineated brain structures. Unfortunately, the interpretation of such an analysis requires caution: in this paper we demonstrate that regional gray matter atrophy, which is concomitant with many neurodegenerative diseases, may itself directly result in a phase shift seemingly indicative of increased iron concentration even without any real change in the tissue iron concentration. Although this effect is relatively small results of large-scale group comparisons may be driven by anatomical changes rather than by changes of the iron concentration.

  3. Longitudinal phase-space coating of beam in a storage ring

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, C.M., E-mail: cbhat@fnal.gov

    2014-06-13

    In this Letter, I report on a novel scheme for beam stacking without any beam emittance dilution using a barrier rf system in synchrotrons. The general principle of the scheme called longitudinal phase-space coating, validation of the concept via multi-particle beam dynamics simulations applied to the Fermilab Recycler, and its experimental demonstration are presented. In addition, it has been shown and illustrated that the rf gymnastics involved in this scheme can be used in measuring the incoherent synchrotron tune spectrum of the beam in barrier buckets and in producing a clean hollow beam in longitudinal phase space. The method of beam stacking in synchrotrons presented here is the first of its kind.

  4. Prototype system for phase advance measurements of LHC small beam oscillations

    CERN Document Server

    Olexa, J; Brezovic, Z; Gasior, M

    2013-01-01

    Magnet lattice parameters of the Large Hadron Collider (LHC) are measured by exciting beam transverse oscillations that allow measuring their phase advance using the beam position measurement (BPM) system. However, the BPM system requires millimetre oscillation amplitudes, with which nominal high intensity beams would cause large particle loss, dangerous for the LHC superconducting magnets. Therefore, such measurements cannot be done often, as they require special low intensity beams with important set-up time. After its first long shut-down the LHC will be equipped with new collimators with embedded BPMs, for which a new front-end electronics has been developed. Its main processing channels based on compensated diode detectors are designed for beam orbit measurement with sub-micrometre resolution. It is planned to extend this system by adding dedicated channels optimised for phase advance measurement, allowing continuous LHC optics measurement with much smaller beam excitation. This subsystem will be based o...

  5. Passing excellence

    Science.gov (United States)

    Tsoupikova, Daria

    2007-02-01

    This paper describes the research and development of a virtual reality visualization project "Passing excellence" about the world famous architectural ensemble "Kizhi". The Kizhi Pogost is located on an island in Lake Onega in northern Karelia in Russia. It is an authentic museum of an ancient wood building tradition which presents a unique artistic achievement. This ensemble preserves a concentration of masterpieces of the Russian heritage and is included in the List of Most Endangered Sites of the World Monuments Watch protected by World Heritage List of UNESCO. The project strives to create a unique virtual observation of the dynamics of the architectural changes of the museum area beginning from the 15th Century up to the 21st Century. The visualization is being created to restore the original architecture of Kizhi island based on the detailed photographs, architectural and geometric measurements, textural data, video surveys and resources from the Kizhi State Open-Air Museum archives. The project is being developed using Electro, an application development environment for the tiled display high-resolution graphics visualization system and can be shown on the virtual reality systems such as the GeoWall TM and the C-Wall.

  6. Nonlinear propagation of phase-conjugate focused sound beams in water

    Science.gov (United States)

    Brysev, A. P.; Krutyansky, L. M.; Preobrazhensky, V. L.; Pyl'nov, Yu. V.; Cunningham, K. B.; Hamilton, M. F.

    2000-07-01

    Nonlinear propagation of phase-conjugate, focused, ultrasound beams is studied. Measurements are presented of harmonic amplitudes along the axis and in the focal plane of the conjugate beam, and of the waveform and spectrum at the focus. A maximum peak pressure of 3.9 MPa was recorded in the conjugate beam. The measurements are compared with simulations based on the KZK equation, and satisfactory agreement is obtained.

  7. Combining Generalized Phase Contrast with matched filtering into a versatile beam shaping approach

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Palima, Darwin

    2010-01-01

    We adapt concepts from matched filtering to propose a method for generating reconfigurable multiple beams. Combined with the Generalized Phase Contrast (GPC) technique, the proposed method coined mGPC can yield dynamically reconfigurable optical beam arrays with high light efficiency for optical...... manipulation, high-speed sorting and other parallel spatial light applications [1]....

  8. A superconducting radio-frequency cavity for manipulating the phase space of pion beams at LAMPF

    Energy Technology Data Exchange (ETDEWEB)

    O' Donnell, J.M.; Davis, J.; DeHaven, R.A.; Gray, E.; Johnson, R.; Lomax, R.E.; McCloud, B.J.; McGill, J.A.; Morris, C.L.; Novak, J.; Rusnak, B.; Tubb, G. (Los Alamos National Lab., Los Alamos, NM (United States)); Applegate, J.M.; Averett, T.D.; Beck, J.; Ritchie, B.G. (Arizona State Univ., Tempe, AZ (United States)); Haebel, E. (CERN, Geneva (Switzerland)); Kiehlmann, D.; Klein, U.; Peniger, M.; Schaefer, P.; Vogel, H. (Siemens AG, Accelerator and Magnet Technology, Bergisch Gladbach (Germany)); Ward, H.; Moore, C.F. (Univ. of Texas, Austin, TX (United States))

    1992-07-15

    The SCRUNCHER is a superconducting radio-frequency cavity for manipulating the longitudinal phase space of the secondary pion beam from the low energy pion channel at LAMPF. Test results of the cavity performance and initial results from in-beam tests are presented. (orig.).

  9. A superconducting radio-frequency cavity for manipulating the phase space of pion beams at LAMPF

    Science.gov (United States)

    O'Donnell, J. M.; Davis, J.; DeHaven, R. A.; Gray, E.; Johnson, R.; Lomax, R. E.; McCloud, B. J.; McGill, J. A.; Morris, C. L.; Novak, J.; Rusnak, B.; Tubb, G.; Applegate, J. M.; Averett, T. D.; Beck, J.; Ritchie, B. G.; Haebel, E.; Kiehlmann, D.; Klein, U.; Peiniger, M.; Schäfer, P.; Vogel, H.; Ward, H.; Fred Moore, C.

    1992-07-01

    The SCRUNCHER is a superconducting radio-frequency cavity for manipulating the longitudinal phase space of the secondary pion beam from the low energy pion channel at LAMPF. Test results of the cavity performance and initial results from in-beam tests are presented.

  10. Phase modulated high density collinear holographic data storage system with phase-retrieval reference beam locking and orthogonal reference encoding.

    Science.gov (United States)

    Liu, Jinpeng; Horimai, Hideyoshi; Lin, Xiao; Huang, Yong; Tan, Xiaodi

    2018-02-19

    A novel phase modulation method for holographic data storage with phase-retrieval reference beam locking is proposed and incorporated into an amplitude-encoding collinear holographic storage system. Unlike the conventional phase retrieval method, the proposed method locks the data page and the corresponding phase-retrieval interference beam together at the same location with a sequential recording process, which eliminates piezoelectric elements, phase shift arrays and extra interference beams, making the system more compact and phase retrieval easier. To evaluate our proposed phase modulation method, we recorded and then recovered data pages with multilevel phase modulation using two spatial light modulators experimentally. For 4-level, 8-level, and 16-level phase modulation, we achieved the bit error rate (BER) of 0.3%, 1.5% and 6.6% respectively. To further improve data storage density, an orthogonal reference encoding multiplexing method at the same position of medium is also proposed and validated experimentally. We increased the code rate of pure 3/16 amplitude encoding method from 0.5 up to 1.0 and 1.5 using 4-level and 8-level phase modulation respectively.

  11. Coherent-phase or random-phase acceleration of electron beams in solar flares

    Science.gov (United States)

    Aschwanden, Markus J.; Benz, Arnold O.; Montello, Maria L.

    1994-01-01

    Time structures of electron beam signatures at radio wavelengths are investigated to probe correlated versus random behavior in solar flares. In particular we address the issue whether acceleration and injection of electron beams is coherently modulated by a single source, or whether the injection is driven by a stochastic (possibly spatially fragmented) process. We analyze a total of approximately = 6000 type III bursts observed by Ikarus (Zurich) in the frequency range of 100-500 MHz, during 359 solar flares with simultaneous greater than or = 25 keV hard X-ray emission, in the years 1890-1983. In 155 flares we find a total of 260 continuous type III groups, with an average number of 13 +/- 9 bursts per group, a mean duration of D = 12 +/- 14 s, a mean period of P = 2.0 +/- 1.2 s, with the highest burst rate at a frequency of nu = 310 +/- 120 MHz. Pulse periods have been measured between 0.5 and 10 s, and can be described by an exponential distribution, i.e., N(P) varies as e (exp -P/1.0s). The period shows a frequency dependence of P(nu)=46(exp-0.6)(sub MHz)s for different flares, but is invariant during a particular flare. We measure the mean period P and its standard deviation sigma (sub p) in each type III group, and quantify the degree of periodicity (or phase-coherence) by the dimensionless parameter sigma (sub p)P. The representative sample of 260 type III burst groups shows a mean periodicity of sigma (sub p/P) = 0.37 +/- 0.12, while Monte Carlo simulations of an equivalent set of truly random time series show a distinctly different value of sigma (sub p)P = 0.93 +/- 0.26. This result indicates that the injection of electron beams is coherently modulated by a particle acceleration source which is either compact or has a global organization on a timescale of seconds, in contrast to an incoherent acceleration source, which is stochastic either in time or space. We discuss the constraints on the size of the acceleration region resulting from electron beam

  12. Characterization of quasi-phase-matching gratings in quadratic media through double-pass second-harmonic power measurements

    DEFF Research Database (Denmark)

    Johansen, Steffen Kjær; Baldi, Pascal

    2004-01-01

    A new scheme for nondestructive characterization of quasi-phase-matching grating structures and temperature gradients through inverse Fourier theory using second-harmonic-generation experiments is proposed. By inserting a mirror to reflect the signals back through the sample, we show how...

  13. The effect of phase advance errors between interaction points on beam halos

    International Nuclear Information System (INIS)

    Chen, T.; Irwin, J.; Siemann, R.H.

    1995-01-01

    Phase advance errors between interaction points (IP) break the symmetry of multi-IP colliders. This symmetry breaking introduces new, lower order resonances which may chance the halo from the beam-beam interaction dramatically. In this paper, the mechanism of introducing new resonances is discussed. Simulation results showing the changes due to phase advance errors are presented. Simulation results are compared with experimental measurements at VEPP-2M

  14. Hollow beam creation with diffractive phase masks at PHELIX

    Energy Technology Data Exchange (ETDEWEB)

    Brabetz, Christian [Goethe Univ. Frankfurt am Main (Germany); Busold, Simon; Deppert, Oliver; Wagner, Florian [Technische Universitaet Darmstadt, Karolinenplatz 5, 64289 Darmstadt (Germany); Kester, Oliver [Goethe Univ. Frankfurt am Main (Germany); Technische Universitaet Darmstadt, Karolinenplatz 5, 64289 Darmstadt (Germany); Schumacher, Dennis; Zielbauer, Bernhard; Bagnoud, Vincent [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Planckstrasse 1, 64291 Darmstadt (Germany); Collaboration: LIGHT-Collaboration

    2013-07-01

    In the framework of the Laser Ion Generation Handling and Transport (LIGHT) research project at GSI, the reduction of the divergence of the laser accelerated ions is a central issue. One solution resides on engineering the electron sheath using in TNSA for reducing the initial divergence of the ion beam. In our first attempt, we were successful in creating and propagating a *donut* laser mode at the PHELIX laser. We have then conducted a experimental campaign at PHELIX One sees a qualitative effect of the focal spot beam shape on the ion beam divergence as expected. The energy cut-off in the proton spectrum was nearly higher when a donut focus was applied, although this resulted in contradiction with the intensity scaling law of TNSA.

  15. A Unified Algorithm for Channel Imbalance and Antenna Phase Center Position Calibration of a Single-Pass Multi-Baseline TomoSAR System

    Directory of Open Access Journals (Sweden)

    Yuncheng Bu

    2018-03-01

    Full Text Available The multi-baseline synthetic aperture radar (SAR tomography (TomoSAR system is employed in such applications as disaster remote sensing, urban 3-D reconstruction, and forest carbon storage estimation. This is because of its 3-D imaging capability in a single-pass platform. However, a high 3-D resolution of TomoSAR is based on the premise that the channel imbalance and antenna phase center (APC position are precisely known. If this is not the case, the 3-D resolution performance will be seriously degraded. In this paper, a unified algorithm for channel imbalance and APC position calibration of a single-pass multi-baseline TomoSAR system is proposed. Based on the maximum likelihood method, as well as the least squares and the damped Newton method, we can calibrate the channel imbalance and APC position. The algorithm is suitable for near-field conditions, and no phase unwrapping operation is required. The effectiveness of the proposed algorithm has been verified by simulation and experimental results.

  16. An Optimal Beamforming Algorithm for Phased-Array Antennas Used in Multi-Beam Spaceborne Radiometers

    DEFF Research Database (Denmark)

    Iupikov, O. A.; Ivashina, M. V.; Pontoppidan, K.

    2015-01-01

    Strict requirements for future spaceborne ocean missions using multi-beam radiometers call for new antenna technologies, such as digital beamforming phased arrays. In this paper, we present an optimal beamforming algorithm for phased-array antenna systems designed to operate as focal plane arrays...... to a FPA feeding a torus reflector antenna (designed under the contract with the European Space Agency) and tested for multiple beams. The results demonstrate an improved performance in terms of the optimized beam characteristics, yielding much higher spatial and radiometric resolution as well as much...

  17. Optical method for mapping the transverse phase space of a charged particle beam

    International Nuclear Information System (INIS)

    Fiorito, R.B.; Shkvarunets, A.G.; O'Shea, P.G.

    2002-01-01

    We are developing an all optical method to map the transverse phase space map of a charged particle beam. Our technique employs OTR interferometry (OTRI) in combination with a scanning pinhole to make local orthogonal (x,y) divergence and trajectory angle measurements as function of position within the transverse profile of the beam. The localized data allows a reconstruction of the horizontal and vertical phase spaces of the beam. We have also demonstrated how single and multiple pinholes can in principle be used to make such measurements simultaneously

  18. Non-destructive characterisation of polymers and Al-alloys by polychromatic cone-beam phase contrast tomography

    International Nuclear Information System (INIS)

    Kastner, Johann; Plank, Bernhard; Requena, Guillermo

    2012-01-01

    X-ray computed tomography (XCT) has become a very important tool for the non-destructive characterisation of materials. Continuous improvements in the quality and performance of X-ray tubes and detectors have led to cone-beam XCT systems that can now achieve spatial resolutions down to 1 μm and even below. Since not only the amplitude but also the phase of an X-ray beam is altered while passing through an object, phase contrast effects can occur even for polychromatic sources when the spatial coherence due to a small focal spot size is high enough. This can lead to significant improvements over conventional attenuation-based X-ray computed tomography. Phase contrast can increase by edge enhancement the visibility of small structures and of features which are only slightly different in attenuation. We report on the possibilities of polychromatic cone-beam phase contrast tomography for non-destructive characterisation of materials. A carbon fibre-reinforced polymer and the Al-alloys AlMg5Si7 and AlSi18 were investigated with high resolution cone-beam X-ray computed tomography with a polychromatic tube source. Under certain conditions strong phase contrast resulting in an upward and downward overshooting of the grey values across edges was observed. The phase effects are much stronger for the polymer than for the Al-alloys. The influence on the phase contrast of the parameters, including source-detector distance, focal spot size and tube acceleration voltage is presented. Maximum phase contrast was observed for a maximum distance between the source and the detector, for a low voltage and a minimum focal spot size at the X-ray source. The detectability of the different phases is improved by the edge enhancement and the resulting improvement of sharpness. Thus, a better segmentation of the carbon fibres in the fibre-reinforced polymer and of the Mg 2 Si-phase in the AlMg5Si7-alloy is achieved. Primary and eutectic Si cannot be detected by attenuation-based X

  19. Theory of third-harmonic generation using Bessel beams, and self-phase-matching

    International Nuclear Information System (INIS)

    Tewari, S.P.; Huang, H.; Boyd, R.W.

    1996-01-01

    Taking Bessel beams (J 0 beam) as a representation of a conical beam, and a slowly varying envelope approximation (SVEA) we obtain the results for the theory of third-harmonic generation from an atomic medium. We demonstrate how the phenomenon of self-phase-matching is contained in the transverse-phase-matching integral of the theory. A method to calculate the transverse-phase-matching integral containing four Bessel functions is described which avoids the computer calculations of the Bessel functions. In order to consolidate the SVEA result an alternate method is used to obtain the exact result for the third-harmonic generation. The conditions are identified in which the exact result goes over to the result of the SVEA. The theory for multiple Bessel beams is also discussed which has been shown to be the source of the wide width of the efficiency curve of the third-harmonic generation observed in experiments. copyright 1996 The American Physical Society

  20. Measurement of beam phase at FLASH using HOMs in accelerating cavities

    CERN Document Server

    Shi, Lianliang; Jones, Roger M; Joshi, Nirav

    2017-01-01

    The beam phase relative to the accelerating field is of vital importance for the quality of photon beams produced in modern Free Electron Lasers based on superconducting cavities. Normally, the phase is determined by detecting the transient field induced by the beam. In this way the phase of each cavity is checked and adjusted typically every few months. In this paper, we present an on-line method of beam phase determination, based on higher order modes (HOMs) excited in the 2nd monopole band by the beam inside these cavities. A circuit model of this HOM band is also presented. Various effects on the resolution have been studied. The results indicate that the resolution is strongly dependent on the signal to noise ratio and the sampling rate. Preliminary experimental results, based on a broadband setup, reveal a resolution of ca. 0.1° RMS. These are in good agreement with simulation results. The work will pave the way for a dedicated system of beam phase monitoring, which is under development for the Europea...

  1. Beam Line and Associated Work: Operational Phase 1985-1987

    Science.gov (United States)

    1988-08-26

    ENEA FEL experiment. F. Cicci, E. Fiorentino. A. Ranieri, E. Sabie. Centro Ricerche Energia Frascati (Italy?. ....................... 169 582.25...C) knife-edge pinhole bracket (cf. Fig. 14); (D) beam stop; (E) calorimeter with an attached Si solar cell detector; (F) paddle with tilted platforms...used for T real-time signal pickup behind the slit was a standard Si solar cell, epoxied to the calorimeter case (detail . in Fig. 5). The experimental

  2. Phase space imaging of a beam of charged particles by frictional forces

    International Nuclear Information System (INIS)

    Daniel, H.

    1977-01-01

    In the case of frictional forces, defined by always acting opposite to the particle motion, Liouville's theorem does not apply. The effect of such forces on a beam of charged particles is calculated in closed form. Emphasis is given to the phase space imaging by a moderator. Conditions for an increase in phase space density are discussed. (Auth.)

  3. Correction of aberrations in beams filling elliptical phase-space areas

    International Nuclear Information System (INIS)

    Wollnik, H.

    1988-01-01

    For the optimization of an optical system it is advantageous to amend the system by a virtual object lens so that the calculation always starts from an upright phase-space distribution. Furthermore, in case of a beam filling an elliptical phase-space volume, the most extreme rays of a beam, filling a parallelogram-like phase-space volume, do not exist, so that the corresponding sum of aberrations is smaller. For an optimization thus corresponding attenuation factors should be taken into accout

  4. A reconstruction method for cone-beam differential x-ray phase-contrast computed tomography.

    Science.gov (United States)

    Fu, Jian; Velroyen, Astrid; Tan, Renbo; Zhang, Junwei; Chen, Liyuan; Tapfer, Arne; Bech, Martin; Pfeiffer, Franz

    2012-09-10

    Most existing differential phase-contrast computed tomography (DPC-CT) approaches are based on three kinds of scanning geometries, described by parallel-beam, fan-beam and cone-beam. Due to the potential of compact imaging systems with magnified spatial resolution, cone-beam DPC-CT has attracted significant interest. In this paper, we report a reconstruction method based on a back-projection filtration (BPF) algorithm for cone-beam DPC-CT. Due to the differential nature of phase contrast projections, the algorithm restrains from differentiation of the projection data prior to back-projection, unlike BPF algorithms commonly used for absorption-based CT data. This work comprises a numerical study of the algorithm and its experimental verification using a dataset measured with a three-grating interferometer and a micro-focus x-ray tube source. Moreover, the numerical simulation and experimental results demonstrate that the proposed method can deal with several classes of truncated cone-beam datasets. We believe that this feature is of particular interest for future medical cone-beam phase-contrast CT imaging applications.

  5. Phase-preserving beam expander for biomedical X-ray imaging

    International Nuclear Information System (INIS)

    Martinson, Mercedes; Samadi, Nazanin; Bassey, Bassey; Gomez, Ariel; Chapman, Dean

    2015-01-01

    Building on previous work, a phase-preserving bent Laue beam-expanding monochromator was developed with the capability of performing live animal phase contrast dynamic imaging at the Biomedical Imaging and Therapy beamline at the Canadian Light Source. The BioMedical Imaging and Therapy beamlines at the Canadian Light Source are used by many researchers to capture phase-based imaging data. These experiments have so far been limited by the small vertical beam size, requiring vertical scanning of biological samples in order to image their full vertical extent. Previous work has been carried out to develop a bent Laue beam-expanding monochromator for use at these beamlines. However, the first attempts exhibited significant distortion in the diffraction plane, increasing the beam divergence and eliminating the usefulness of the monochromator for phase-related imaging techniques. Recent work has been carried out to more carefully match the polychromatic and geometric focal lengths in a so-called ‘magic condition’ that preserves the divergence of the beam and enables full-field phase-based imaging techniques. The new experimental parameters, namely asymmetry and Bragg angles, were evaluated by analysing knife-edge and in-line phase images to determine the effect on beam divergence in both vertical and horizontal directions, using the flat Bragg double-crystal monochromator at the beamline as a baseline. The results show that by using the magic condition, the difference between the two monochromator types is less than 10% in the diffraction plane. Phase fringes visible in test images of a biological sample demonstrate that this difference is small enough to enable in-line phase imaging, despite operating at a sub-optimal energy for the wafer and asymmetry angle that was used

  6. Synchronous phase and energy measurement system for a 6.7-MeV H- beam

    International Nuclear Information System (INIS)

    Gilpatrick, J.D.; Meyer, R.E.; Wells, F.D.; Power, J.F.; Shafer, R.E.

    1988-01-01

    A noninterceptive measurement system has been built to measure the energy and synchronous phase of a 6.7-MeV proton beam drifting from the ramped-gradient, drift-tube linac (RGDTL) in the accelerator test stand (ATS) facility. Axially-symmetric, capacitive probes used in these measurements produce signals that are proportional to the beam image current on their inner rings. Signals from two of these probes separated by 92.6 cm are down-converted from 425 to 20 MHz. The phase difference between these 20-MHz signals is then detected with an electronic, phase-comparator circuit. The phase-comparator signal output is a voltage that is related to momentum of the beam. A phase comparison is also provided between the 425-MHz fundamental rf field inside the RGDTL and the capacitive probe located nearest the RGDTL output. The total estimated error for the absolute and relative energy measurement is less than +- 12.2 and +- 3.1 keV, respectively. The total estimated error for the relative synchronous phase measurement is less than +-1/degree/. Beam energy versus synchronous phase experimental data agree with computer simulations. 3 refs., 3 figs., 1 tab

  7. Impact of phase errors at the conjugate step on the propagation of intensity and phase shaped laser beams

    CSIR Research Space (South Africa)

    Litvin, IA

    2007-01-01

    Full Text Available The authors investigate the phase conjugating element of a two element Fourier transform beam shaping scheme and the impact this element has on the resulting propagation. It is shown that there are stricter limitations placed on the system when...

  8. Mathematic model analysis of Gaussian beam propagation through an arbitrary thickness random phase screen.

    Science.gov (United States)

    Tian, Yuzhen; Guo, Jin; Wang, Rui; Wang, Tingfeng

    2011-09-12

    In order to research the statistical properties of Gaussian beam propagation through an arbitrary thickness random phase screen for adaptive optics and laser communication application in the laboratory, we establish mathematic models of statistical quantities, which are based on the Rytov method and the thin phase screen model, involved in the propagation process. And the analytic results are developed for an arbitrary thickness phase screen based on the Kolmogorov power spectrum. The comparison between the arbitrary thickness phase screen and the thin phase screen shows that it is more suitable for our results to describe the generalized case, especially the scintillation index.

  9. A facility for liquid-phase radiation experiments on heavy ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Stuglik, Z; Zvara, I; Yakushev, A B; Timokhin, S N [Flerov Lab. of Nuclear Reactions, Dubna (Russian Federation). Joint Inst. for Nuclear Research

    1994-05-01

    The facility for liquid-phase radiation experiments installed on the beam line of the U-400 cyclotron in the Flerov Laboratory of Nuclear Reactions, JINR, Dubna, is described. The accelerator provides intermediate energy (some 10 MeV/nucleon) beams of ions ranging from Li to Xe. Preliminary results on the radiolysis of the Fricke solution and malachite green in ethanol by {sup 11}B, {sup 24}Mg and {sup 40}Ca ions are presented. (author).

  10. Phase aberrations and beam cleanup techniques in carbon-dioxide laser fusion systems

    International Nuclear Information System (INIS)

    Viswanathan, V.K.

    1981-01-01

    This paper describes the various carbon dioxide laser fusion systems at Los Alamos from the point of view of an optical designer. The types of phase aberrations present in these systems, as well as the beam cleanup techniques that can be used to improve the beam optical quality, are discussed. As this is a review article, some previously published results are also used where relevant

  11. Longitudinal phase space manipulation of an ultrashort electron beam via THz IFEL interaction

    Energy Technology Data Exchange (ETDEWEB)

    Moody, J. T.; Li, R. K.; Musumeci, P.; Scoby, C. M.; To, H. [Department of Physics and Astronomy, UCLA, Los Angeles California, 90095 (United States)

    2012-12-21

    A scheme where a laser locked THz source is used to manipulate the longitudinal phase space of an ultrashort electron beam using an IFEL interaction is investigated. The efficiency of THz source based on the pulse front tilt optical rectification scheme is increased by cryogenic cooling to achieve sufficient THz power for compression and synchronization. Start-to-end simulations describing the evolution of the beam from the cathode to the compression point after the undulator are presented.

  12. Longitudinal phase space manipulation of an ultrashort electron beam via THz IFEL interaction

    International Nuclear Information System (INIS)

    Moody, J. T.; Li, R. K.; Musumeci, P.; Scoby, C. M.; To, H.

    2012-01-01

    A scheme where a laser locked THz source is used to manipulate the longitudinal phase space of an ultrashort electron beam using an IFEL interaction is investigated. The efficiency of THz source based on the pulse front tilt optical rectification scheme is increased by cryogenic cooling to achieve sufficient THz power for compression and synchronization. Start-to-end simulations describing the evolution of the beam from the cathode to the compression point after the undulator are presented.

  13. A Monte Carlo simulation framework for electron beam dose calculations using Varian phase space files for TrueBeam Linacs.

    Science.gov (United States)

    Rodrigues, Anna; Sawkey, Daren; Yin, Fang-Fang; Wu, Qiuwen

    2015-05-01

    To develop a framework for accurate electron Monte Carlo dose calculation. In this study, comprehensive validations of vendor provided electron beam phase space files for Varian TrueBeam Linacs against measurement data are presented. In this framework, the Monte Carlo generated phase space files were provided by the vendor and used as input to the downstream plan-specific simulations including jaws, electron applicators, and water phantom computed in the EGSnrc environment. The phase space files were generated based on open field commissioning data. A subset of electron energies of 6, 9, 12, 16, and 20 MeV and open and collimated field sizes 3 × 3, 4 × 4, 5 × 5, 6 × 6, 10 × 10, 15 × 15, 20 × 20, and 25 × 25 cm(2) were evaluated. Measurements acquired with a CC13 cylindrical ionization chamber and electron diode detector and simulations from this framework were compared for a water phantom geometry. The evaluation metrics include percent depth dose, orthogonal and diagonal profiles at depths R100, R50, Rp, and Rp+ for standard and extended source-to-surface distances (SSD), as well as cone and cut-out output factors. Agreement for the percent depth dose and orthogonal profiles between measurement and Monte Carlo was generally within 2% or 1 mm. The largest discrepancies were observed within depths of 5 mm from phantom surface. Differences in field size, penumbra, and flatness for the orthogonal profiles at depths R100, R50, and Rp were within 1 mm, 1 mm, and 2%, respectively. Orthogonal profiles at SSDs of 100 and 120 cm showed the same level of agreement. Cone and cut-out output factors agreed well with maximum differences within 2.5% for 6 MeV and 1% for all other energies. Cone output factors at extended SSDs of 105, 110, 115, and 120 cm exhibited similar levels of agreement. We have presented a Monte Carlo simulation framework for electron beam dose calculations for Varian TrueBeam Linacs. Electron beam energies of 6 to 20 MeV for open and collimated

  14. Coherent beam combination using self-phase locked stimulated Brillouin scattering phase conjugate mirrors with a rotating wedge for high power laser generation.

    Science.gov (United States)

    Park, Sangwoo; Cha, Seongwoo; Oh, Jungsuk; Lee, Hwihyeong; Ahn, Heekyung; Churn, Kil Sung; Kong, Hong Jin

    2016-04-18

    The self-phase locking of a stimulated Brillouin scattering-phase conjugate mirror (SBS-PCM) allows a simple and scalable coherent beam combination of existing lasers. We propose a simple optical system composed of a rotating wedge and a concave mirror to overcome the power limit of the SBS-PCM. Its phase locking ability and the usefulness on the beam-combination laser are demonstrated experimentally. A four-beam combination is demonstrated using this SBS-PCM scheme. The relative phases between the beams were measured to be less than λ/24.7.

  15. Experimental evidence of adiabatic splitting of charged particle beams using stable islands of transverse phase space

    Directory of Open Access Journals (Sweden)

    S. Gilardoni

    2006-10-01

    Full Text Available Recently, a novel technique to perform multiturn extraction from a circular particle accelerator was proposed. It is based on beam splitting and trapping, induced by a slow crossing of a nonlinear resonance, inside stable islands of transverse phase space. Experiments at the CERN Proton Synchrotron started in 2002 and evidence of beam splitting was obtained by summer 2004. In this paper, the measurement results achieved with both a low- and a high-intensity, single-bunch proton beam are presented.

  16. Generation of equal-intensity coherent optical beams by binary geometrical phase on metasurface

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zheng-Han; Jiang, Shang-Chi; Xiong, Xiang; Peng, Ru-Wen, E-mail: rwpeng@nju.edu.cn, E-mail: muwang@nju.edu.cn; Wang, Mu, E-mail: rwpeng@nju.edu.cn, E-mail: muwang@nju.edu.cn [National Laboratory of Solid State Microstructures and School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2016-06-27

    We report here the design and realization of a broadband, equal-intensity optical beam splitter with a dispersion-free binary geometric phase on a metasurface with unit cell consisting of two mirror-symmetric elements. We demonstrate experimentally that two identical beams can be efficiently generated with incidence of any polarization. The efficiency of the device reaches 80% at 1120 nm and keeps larger than 70% in the range of 1000–1400 nm. We suggest that this approach for generating identical, coherent beams have wide applications in diffraction optics and in entangled photon light source for quantum communication.

  17. Transverse phase space mapping of relativistic electron beams using optical transition radiation

    Directory of Open Access Journals (Sweden)

    G. P. Le Sage

    1999-12-01

    Full Text Available Optical transition radiation (OTR has proven to be a versatile and effective diagnostic for measuring the profile, divergence, and emittance of relativistic electron beams with a wide range of parameters. Diagnosis of the divergence of modern high brightness beams is especially well suited to OTR interference (OTRI techniques, where multiple dielectric or metal foils are used to generate a spatially coherent interference pattern. Theoretical analysis of measured OTR and OTRI patterns allows precise measurement of electron beam emittance characteristics. Here we describe an extension of this technique to allow mapping of divergence characteristics as a function of transverse coordinates within a measured beam. We present the first experimental analysis of the transverse phase space of an electron beam using all optical techniques. Comparing an optically masked portion of the beam to the entire beam, we measure different angular spread and average direction of the particles. Direct measurement of the phase-space ellipse tilt angle has been demonstrated using this optical masking technique.

  18. Beam-pointing error compensation method of phased array radar seeker with phantom-bit technology

    Directory of Open Access Journals (Sweden)

    Qiuqiu WEN

    2017-06-01

    Full Text Available A phased array radar seeker (PARS must be able to effectively decouple body motion and accurately extract the line-of-sight (LOS rate for target missile tracking. In this study, the real-time two-channel beam pointing error (BPE compensation method of PARS for LOS rate extraction is designed. The PARS discrete beam motion principium is analyzed, and the mathematical model of beam scanning control is finished. According to the principle of the antenna element shift phase, both the antenna element shift phase law and the causes of beam-pointing error under phantom-bit conditions are analyzed, and the effect of BPE caused by phantom-bit technology (PBT on the extraction accuracy of the LOS rate is examined. A compensation method is given, which includes coordinate transforms, beam angle margin compensation, and detector dislocation angle calculation. When the method is used, the beam angle margin in the pitch and yaw directions is calculated to reduce the effect of the missile body disturbance and to improve LOS rate extraction precision by compensating for the detector dislocation angle. The simulation results validate the proposed method.

  19. Exploring the QCD Phase Structure with Beam Energy Scan in Heavy-ion Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xiaofeng, E-mail: xfluo@mail.ccnu.edu.cn

    2016-12-15

    Beam energy scan programs in heavy-ion collisions aim to explore the QCD phase structure at high baryon density. Sensitive observables are applied to probe the signatures of the QCD phase transition and critical point in heavy-ion collisions at RHIC and SPS. Intriguing structures, such as dip, peak and oscillation, have been observed in the energy dependence of various observables. In this paper, an overview is given and corresponding physics implications will be discussed for the experimental highlights from the beam energy scan programs at the STAR, PHENIX and NA61/SHINE experiments. Furthermore, the beam energy scan phase II at RHIC (2019–2020) and other future experimental facilities for studying the physics at low energies will be also discussed.

  20. Numerical investigation of multichannel laser beam phase locking in turbulent atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, V A; Volkov, M V; Garanin, S G; Starikov, F A [Russian Federal Nuclear Center ' All-Russian Research Institute of Experimental Physics' , Sarov, Nizhnii Novgorod region (Russian Federation)

    2015-12-31

    The efficiency of coherent multichannel beam combining under focusing through a turbulent medium on a target in the cases of phase conjugation and target irradiation in the feedback loop is investigated numerically in various approximations. The conditions of efficient focusing of multichannel radiation on the target are found. It is shown that the coherent beam combining with target irradiation in the feedback loop, which does not require a reference beam and wavefront measurements, is as good as the phase conjugation approach in the efficiency of focusing. It is found that the main effect of focusing is provided by properly chosen phase shifts in the channels, whereas taking into account local wavefront tip tilts weakly affects the result. (control of laser radiation parameters)

  1. Two-phase flow instrumentation and laser beams

    International Nuclear Information System (INIS)

    Delhaye, J.M.

    1976-01-01

    Some methods based on laser techniques in order to place emphasis on the relation between measured quantities and the primary variables entering the general equations of two-phase systems are reviewed and summarized. The case where the bubbles or droplets are so small that they act as individual scattering centers is excluded [fr

  2. Image grating metrology using phase-stepping interferometry in scanning beam interference lithography

    Science.gov (United States)

    Li, Minkang; Zhou, Changhe; Wei, Chunlong; Jia, Wei; Lu, Yancong; Xiang, Changcheng; Xiang, XianSong

    2016-10-01

    Large-sized gratings are essential optical elements in laser fusion and space astronomy facilities. Scanning beam interference lithography is an effective method to fabricate large-sized gratings. To minimize the nonlinear phase written into the photo-resist, the image grating must be measured to adjust the left and right beams to interfere at their waists. In this paper, we propose a new method to conduct wavefront metrology based on phase-stepping interferometry. Firstly, a transmission grating is used to combine the two beams to form an interferogram which is recorded by a charge coupled device(CCD). Phase steps are introduced by moving the grating with a linear stage monitored by a laser interferometer. A series of interferograms are recorded as the displacement is measured by the laser interferometer. Secondly, to eliminate the tilt and piston error during the phase stepping, the iterative least square phase shift method is implemented to obtain the wrapped phase. Thirdly, we use the discrete cosine transform least square method to unwrap the phase map. Experiment results indicate that the measured wavefront has a nonlinear phase around 0.05 λ@404.7nm. Finally, as the image grating is acquired, we simulate the print-error written into the photo-resist.

  3. Development of a Beam-based Phase Feedforward Demonstration at the CLIC Test Facility (CTF3)

    CERN Document Server

    AUTHOR|(CDS)2083344; Christian, Glenn

    The Compact Linear Collider (CLIC) is a proposal for a future linear electron--positron collider that could achieve collision energies of up to 3~TeV. In the CLIC concept the main high energy beam is accelerated using RF power extracted from a high intensity drive beam, achieving an accelerating gradient of 100~MV/m. This scheme places strict tolerances on the drive beam phase stability, which must be better than $0.2^\\circ$ at 12~GHz. To achieve the required phase stability CLIC proposes a high bandwidth (${>}17.5$~MHz), low latency drive beam ``phase feedforward'' (PFF) system. In this system electromagnetic kickers, powered by 500~kW amplifiers, are installed in a chicane and used to correct the phase by deflecting the beam on to longer or shorter trajectories. A prototype PFF system has been installed at the CLIC Test Facility, CTF3; the design, operation and commissioning of which is the focus of this work. Two kickers have been installed in the pre-existing chicane in the TL2 transfer line at CTF3 for t...

  4. Laser scanning confocal microscope with programmable amplitude, phase, and polarization of the illumination beam.

    Science.gov (United States)

    Boruah, B R; Neil, M A A

    2009-01-01

    We describe the design and construction of a laser scanning confocal microscope with programmable beam forming optics. The amplitude, phase, and polarization of the laser beam used in the microscope can be controlled in real time with the help of a liquid crystal spatial light modulator, acting as a computer generated hologram, in conjunction with a polarizing beam splitter and two right angled prisms assembly. Two scan mirrors, comprising an on-axis fast moving scan mirror for line scanning and an off-axis slow moving scan mirror for frame scanning, configured in a way to minimize the movement of the scanned beam over the pupil plane of the microscope objective, form the XY scan unit. The confocal system, that incorporates the programmable beam forming unit and the scan unit, has been implemented to image in both reflected and fluorescence light from the specimen. Efficiency of the system to programmably generate custom defined vector beams has been demonstrated by generating a bottle structured focal volume, which in fact is the overlap of two cross polarized beams, that can simultaneously improve both the lateral and axial resolutions if used as the de-excitation beam in a stimulated emission depletion confocal microscope.

  5. A study of phase control in the FEL [free electron laser] two-beam accelerator

    International Nuclear Information System (INIS)

    Sessler, A.M.; Whittum, D.H.; Wurtele, J.S.

    1989-08-01

    A formalism is developed for the analysis of a steady-state free electron laser (FEL) and is applied to the two-beam accelerator (TBA). Conditions are derived for the design of a FEL TBA with rf output power and phase insensitive to errors in both beam current and energy. An example is presented of a suitably phase insensitive TBA design with 100 reaccelerations employing untapered FEL sections and with low power rf input to each section. The theoretical analysis is confirmed by a single particle FEL simulations. 9 refs., 2 tabs

  6. The STAR beam energy scan phase II physics and upgrades

    Czech Academy of Sciences Publication Activity Database

    Yang, C.; Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Bielčík, J.; Bielčíková, Jana; Chaloupka, P.; Federič, Pavol; Rusňák, Jan; Rusňáková, O.; Šimko, Miroslav; Šumbera, Michal; Vértési, Robert

    2017-01-01

    Roč. 967, č. 11 (2017), s. 800-803 ISSN 0375-9474 R&D Projects: GA MŠk LG15001; GA MŠk LM2015054 Institutional support: RVO:61389005 Keywords : STAR collaboration * BES-II * detector upgrade * QCD phase diagram * physics oppotrunity Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nuclear physics Impact factor: 1.916, year: 2016

  7. A dynamic plasmonic manipulation technique assisted by phase modulation of an incident optical vortex beam

    International Nuclear Information System (INIS)

    Yuan, G H; Wang, Q; Tan, P S; Lin, J; Yuan, X-C

    2012-01-01

    A novel phase modulation method for dynamic manipulation of surface plasmon polaritons (SPPs) with a phase engineered optical vortex (OV) beam illuminating on nanoslits is experimentally demonstrated. Because of the unique helical phase carried by an OV beam, dynamic control of SPP multiple focusing and standing wave generation is realized by changing the OV beam’s topological charge constituent with the help of a liquid-crystal spatial light modulator. Measurement of SPP distributions with near-field scanning optical microscopy showed an excellent agreement with numerical predictions. The proposed phase modulation technique for manipulating SPPs features has seemingly dynamic and reconfigurable advantages, with profound potential for development of SPP coupling, routing, multiplexing and high-resolution imaging devices on plasmonic chips. (paper)

  8. Metasurfaces-based holography and beam shaping: engineering the phase profile of light

    Directory of Open Access Journals (Sweden)

    Scheuer Jacob

    2016-08-01

    Full Text Available The ability to engineer and shape the phase profile of optical beams is in the heart of any optical element. Be it a simple lens or a sophisticated holographic element, the functionality of such components is dictated by their spatial phase response. In contrast to conventional optical components which rely on thickness variation to induce a phase profile, metasurfaces facilitate the realization of arbitrary phase distributions using large arrays with sub-wavelength and ultrathin (tens of nanometers features. Such components can be easily realized using a single lithographic step and is highly suited for patterning a variety of substrates, including nonplanar and soft surfaces. In this article, we review the recent developments, potential, and opportunities of metasurfaces applications. We focus primarily on flat optical devices, holography, and beam-shaping applications as these are the key ingredients needed for the development of a new generation of optical devices which could find widespread applications in photonics.

  9. The role of the crystal rotation axis in experimental three- and four-beam phase determination

    International Nuclear Information System (INIS)

    Post, B.; Gong, P.P.; Kern, L.; Ladell, J.

    1986-01-01

    The geometry of four-beam diffraction and procedures for generating it systematically are described. These utilize relatively simple Renninger-type experimental arrangements. The four reciprocal-lattice points involved in each four-beam interaction are located at the corners of rectangles or symmetrical trapezoids in reciprocal space. One of the sides, or a diagonal, of each such quadrilateral serves as the axis of the azimuthal rotation of the crystal. Experiments designed to compare the relative merits of different types of rotation axes have been carried out. It is found that axes of twofold (or higher) symmetry provide advantages over alternate arrangements for experimental phase determination. Four-beam interations are then generated systematically and in greater abundance than in all other n-beam interations combined (n > 2). Such interactions usually provide stronger phase indications than comparable three-beam interaction. The experiments also showed that, although the phase of an 'invariant' quartet is clearly invariant to the choice of unit-cell origin, it is not necessarily invariant to a change of rotation axis from one two-fold axis to another. (orig.)

  10. Efficient coherent beam combination of two-dimensional phase-locked laser arrays

    International Nuclear Information System (INIS)

    Li, Bing; Yan, Aimin; Liu, Liren; Dai, Enwen; Sun, Jianfeng; Shen, Baoliang; Lv, Xiaoyu; Wu, Yapeng

    2011-01-01

    An efficient technique in which a two-dimensional (2D) phase-locked laser array can be coherently combined into a high power and high quality beam by using a conjugate Dammann grating (CDG) is presented. A theoretical model is established to provide a physical interpretation of the proposed scheme. Using this technique, we investigate analytically and numerically the coherent combination of 2D laser arrays such as 5 × 5 and 32 × 32 arrangements. Far-field distributions and the near-field pattern of the combined beam are calculated and compared with experimental results. A verification experiment with a simulated 5 × 5 2D laser array using an aperture mask has been performed. Calculations and experimental results show that the proposed technique in this paper is an efficient coherent beam combination method to obtain a high power and high quality beam from laser arrays

  11. The generation of flat-top beams by complex amplitude modulation with a phase-only spatial light modulator

    CSIR Research Space (South Africa)

    Hendriks, A

    2012-08-01

    Full Text Available amplitude modulation of the light, i.e., in amplitude and phase. We outline the theoretical concept, and then illustrate its use with the example of the laser beam shaping of Gaussian beams into flat-top beams. We quantify the performance of this approach...

  12. Free electron laser small signal dynamics and inclusion of electron-beam energy phase correlation

    International Nuclear Information System (INIS)

    Dattoli, G.; Giannessi, L.; Ottaviani, P. L.

    1998-01-01

    In this paper are analyzed the problems associated with the generation of coherent radiation by an e-beam, traversing an undulator magnet, with an initial energy-phase correlation. The mechanism of the process are explained and the role played by the bunching is clarified. The effect of the correlation on the stimulated part of the emission is also discussed [it

  13. Orbital angular momentum correlations with a phase-flipped Gaussian mode pump beam

    CSIR Research Space (South Africa)

    Romero, J

    2012-08-01

    Full Text Available -1 Journal of Optics August 2012/ Vol. 14. No 8 Orbital angular momentum correlations with a phase- flipped Gaussian mode pump beam J Romero1,2, D Giovannini1, M G McLaren3,4, E J Galvez5, A Forbes3,4 and M J Padgett1 1 School of Physics...

  14. Design of a ring resonator-based optical beam forming network for phased array receive antennas

    NARCIS (Netherlands)

    van 't Klooster, J.W.J.R.; Roeloffzen, C.G.H.; Meijerink, Arjan; Zhuang, L.; Marpaung, D.A.I.; van Etten, Wim; Heideman, Rene; Leinse, Arne; Schippers, H.; Verpoorte, J.; Wintels, M.

    2008-01-01

    A novel squint-free ring resonator-based optical beam forming network (OBFN) for phased array antennas (PAA) is proposed. It is intended to provide broadband connectivity to airborne platforms via geostationary satellites. In this paper, we present the design of the OBFN and its control system. Our

  15. Probing the phase of the elastic pp scattering amplitude with vortex proton beams

    International Nuclear Information System (INIS)

    Ivanov, I. P.

    2013-01-01

    We show that colliding vortex proton beams instead of (approximate) plane waves can lead to a direct measurement of how the overall phase of the scattering amplitude changes with the scattering angle. In elastic pp scattering, this will open a novel way to measure the parameter ρ(t) and probe the real part of the Pomeron.

  16. Probing the phase of the elastic pp scattering amplitude with vortex proton beams

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, I. P. [IFPA, Universite de Liege, Allee du 6 Aout 17, batiment B5a, 4000 Liege, Belgium Sobolev Institute of Mathematics, Koptyug avenue 4, 630090, Novosibirsk (Russian Federation)

    2013-04-15

    We show that colliding vortex proton beams instead of (approximate) plane waves can lead to a direct measurement of how the overall phase of the scattering amplitude changes with the scattering angle. In elastic pp scattering, this will open a novel way to measure the parameter {rho}(t) and probe the real part of the Pomeron.

  17. Floating-point-based hardware accelerator of a beam phase-magnitude detector and filter for a beam phase control system in a heavy-ion synchrotron application

    International Nuclear Information System (INIS)

    Samman, F.A.; Pongyupinpanich Surapong; Spies, C.; Glesner, M.

    2012-01-01

    A hardware implementation of an adaptive phase and magnitude detector and filter of a beam-phase control system in a heavy ion synchrotron application is presented in this paper. The main components of the hardware are adaptive LMS (Least-Mean-Square) filters and phase and magnitude detectors. The phase detectors are implemented by using a CORDIC (Coordinate Rotation Digital Computer) algorithm based on 32-bit binary floating-point arithmetic data formats. The floating-point-based hardware is designed to improve the precision of the past hardware implementation that were based on fixed-point arithmetics. The hardware of the detector and the adaptive LMS filter have been implemented on a programmable logic device (FPGA) for hardware acceleration purpose. The ideal Matlab/Simulink model of the hardware and the VHDL model of the adaptive LMS filter and the phase and magnitude detector are compared. The comparison result shows that the output signal of the floating-point based adaptive FIR filter as well as the phase and magnitude detector agree with the expected output signal of the ideal Matlab/Simulink model. (authors)

  18. Electron backscatter diffraction studies of focused ion beam induced phase transformation in cobalt

    Energy Technology Data Exchange (ETDEWEB)

    Jones, H.G., E-mail: helen.jones@npl.co.uk [National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW (United Kingdom); Day, A.P. [Aunt Daisy Scientific Ltd, Claremont House, High St, Lydney GL15 5DX (United Kingdom); Cox, D.C. [National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW (United Kingdom); Advanced Technology Institute, University of Surrey, Guildford GU2 7XH (United Kingdom)

    2016-10-15

    A focused ion beam microscope was used to induce cubic to hexagonal phase transformation in a cobalt alloy, of similar composition to that of the binder phase in a hardmetal, in a controlled manner at 0°, 45° and 80° ion incident angles. The cobalt had an average grain size of ~ 20 μm, allowing multiple orientations to be studied, exposed to a range of doses between 6 × 10{sup 7} and 2 × 10{sup 10} ions/μm{sup 2}. Electron backscatter diffraction (EBSD) was used to determine the original and induced phase orientations, and area fractions, before and after the ion beam exposure. On average, less phase transformation was observed at higher incident angles and after lower ion doses. However there was an orientation effect where grains with an orientation close to (111) planes were most susceptible to phase transformation, and (101) the least, where grains partially and fully transformed at varying ion doses. - Highlights: •Ion-induced phase change in FCC cobalt was observed at multiple incidence angles. •EBSD was used to study the relationship between grain orientation and transformation. •Custom software analysed ion dose and phase change with respect to grain orientation. •A predictive capability of ion-induced phase change in cobalt was enabled.

  19. Measurement of in-plane strain with dual beam spatial phase-shift digital shearography

    International Nuclear Information System (INIS)

    Xie, Xin; Chen, Xu; Li, Junrui; Yang, Lianxiang; Wang, Yonghong

    2015-01-01

    Full-field in-plane strain measurement under dynamic loading by digital shearography remains a big challenge in practice. A phase measurement for in-plane strain information within one time frame has to be achieved to solve this problem. This paper presents a dual beam spatial phase-shift digital shearography system with the capacity to measure phase distribution corresponding to in-plane strain information within a single time frame. Two laser beams with different wavelengths are symmetrically arranged to illuminate the object under test, and two cameras with corresponding filters, which enable simultaneous recording of two shearograms, are utilized for data acquisition. The phase information from the recorded shearograms, which corresponds to the in-plane strain, is evaluated by the spatial phase-shift method. The spatial phase-shift shearography system realizes a measurement of the in-plane strain through the introduction of the spatial phase-shift technique, using one frame after the loading and one frame before loading. This paper presents the theory of the spatial phase-shift digital shearography for in-plane strain measurement and its derivation, experimental results, and the technique’s potential. (paper)

  20. Instruments and techniques for analysing the time-resolved transverse phase space distribution of high-brightness electron beams

    International Nuclear Information System (INIS)

    Rudolph, Jeniffa

    2012-01-01

    This thesis deals with the instruments and techniques used to characterise the transverse phase space distribution of high-brightness electron beams. In particular, methods are considered allowing to measure the emittance as a function of the longitudinal coordinate within the bunch (slice emittance) with a resolution in the ps to sub-ps range. The main objective of this work is the analysis of techniques applicable for the time-resolved phase space characterisation for future high-brightness electron beam sources and single-pass accelerators based on these. The competence built up by understanding and comparing different techniques is to be used for the design and operation of slice diagnostic systems for the Berlin Energy Recovery Linac Project (BERLinPro). In the framework of the thesis, two methods applicable for slice emittance measurements are considered, namely the zero-phasing technique and the use of a transverse deflector. These methods combine the conventional quadrupole scan technique with a transfer of the longitudinal distribution into a transverse distribution. Measurements were performed within different collaborative projects. The experimental setup, the measurement itself and the data analysis are discussed as well as measurement results and simulations. In addition, the phase space tomography technique is introduced. In contrast to quadrupole scan-based techniques, tomography is model-independent and can reconstruct the phase space distribution from simple projected measurements. The developed image reconstruction routine based on the Maximum Entropy algorithm is introduced. The quality of the reconstruction is tested using different model distributions, simulated data and measurement data. The results of the tests are presented. The adequacy of the investigated techniques, the experimental procedures as well as the developed data analysis tools could be verified. The experimental and practical experience gathered during this work, the

  1. Effects of source and receiver locations in predicting room transfer functions by a phased beam tracing method

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho; Ih, Jeong-Guon

    2012-01-01

    The accuracy of a phased beam tracing method in predicting transfer functions is investigated with a special focus on the positions of the source and receiver. Simulated transfer functions for various source-receiver pairs using the phased beam tracing method were compared with analytical Green’s...

  2. Thin film phase diagram of iron nitrides grown by molecular beam epitaxy

    Science.gov (United States)

    Gölden, D.; Hildebrandt, E.; Alff, L.

    2017-01-01

    A low-temperature thin film phase diagram of the iron nitride system is established for the case of thin films grown by molecular beam epitaxy and nitrided by a nitrogen radical source. A fine-tuning of the nitridation conditions allows for growth of α ‧ -Fe8Nx with increasing c / a -ratio and magnetic anisotropy with increasing x until almost phase pure α ‧ -Fe8N1 thin films are obtained. A further increase of nitrogen content below the phase decomposition temperature of α ‧ -Fe8N (180 °C) leads to a mixture of several phases that is also affected by the choice of substrate material and symmetry. At higher temperatures (350 °C), phase pure γ ‧ -Fe4N is the most stable phase.

  3. Nature of gallium focused ion beam induced phase transformation in 316L austenitic stainless steel

    International Nuclear Information System (INIS)

    Babu, R. Prasath; Irukuvarghula, S.; Harte, A.; Preuss, M.

    2016-01-01

    The microstructural evolution and chemistry of the ferrite phase (α), which transforms from the parent austenite phase (γ) of 316L stainless steel during gallium (Ga) ion beam implantation in Focused Ion Beam (FIB) instrument was systematically studied as a function of Ga"+ ion dose and γ grain orientations. The propensity for initiation of γ → α phase transformation was observed to be strongly dependent on the orientation of the γ grain with respect to the ion beam direction and correlates well with the ion channelling differences in the γ orientations studied. Several α variants formed within a single γ orientation and the sputtering rate of the material, after the γ → α transformation, is governed by the orientation of α variants. With increased ion dose, there is an evolution of orientation of the α variants towards a variant of higher Ga"+ channelling. Unique topographical features were observed within each specific γ orientation that can be attributed to the orientation of defects formed during the ion implantation. In most cases, γ and α were related by either Kurdjumov-Sachs (KS) or Nishiyama-Wassermann (NW) orientation relationship (OR) while in few, no known OR's were identified. While our results are consistent with gallium enrichment being the cause for the γ → α phase transformation, some observations also suggest that the strain associated with the presence of gallium atoms in the lattice has a far field stress effect that promotes the phase transformation ahead of gallium penetration.

  4. Electrically and spatially controllable PDLC phase gratings for diffraction and modulation of laser beams

    Energy Technology Data Exchange (ETDEWEB)

    Hadjichristov, Georgi B., E-mail: georgibh@issp.bas.bg [Laboratory of Optics and Spectroscopy, Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., BG-1784 Sofia (Bulgaria); Marinov, Yordan G.; Petrov, Alexander G. [Laboratory of Biomolecular Layers, Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., BG-1784 Sofia, Bulgaria (Bulgaria)

    2016-03-25

    We present a study on electrically- and spatially-controllable laser beam diffraction, electrooptic (EO) phase modulation, as well as amplitude-frequency EO modulation by single-layer microscale polymer-dispersed liquid crystal (PDLC) phase gratings (PDLC SLPGs) of interest for device applications. PDLC SLPGs were produced from nematic liquid crystal (LC) E7 in photo-curable NOA65 polymer. The wedge-formed PDLC SLPGs have a continuously variable thickness (2–25 µm). They contain LC droplets of diameters twice as the layer thickness, with a linear-gradient size distribution along the wedge. By applying alternating-current (AC) electric field, the PDLC SLPGs produce efficient: (i) diffraction splitting of transmitted laser beams; (ii) spatial redistribution of diffracted light intensity; (iii) optical phase modulation; (iv) amplitude-frequency modulation, all controllable by the driven AC field and the droplet size gradient.

  5. Electron-beam-irradiation-induced crystallization of amorphous solid phase change materials

    Science.gov (United States)

    Zhou, Dong; Wu, Liangcai; Wen, Lin; Ma, Liya; Zhang, Xingyao; Li, Yudong; Guo, Qi; Song, Zhitang

    2018-04-01

    The electron-beam-irradiation-induced crystallization of phase change materials in a nano sized area was studied by in situ transmission electron microscopy and selected area electron diffraction. Amorphous phase change materials changed to a polycrystalline state after being irradiated with a 200 kV electron beam for a long time. The results indicate that the crystallization temperature strongly depends on the difference in the heteronuclear bond enthalpy of the phase change materials. The selected area electron diffraction patterns reveal that Ge2Sb2Te5 is a nucleation-dominated material, when Si2Sb2Te3 and Ti0.5Sb2Te3 are growth-dominated materials.

  6. Wideband two-port beam splitter of a binary fused-silica phase grating.

    Science.gov (United States)

    Wang, Bo; Zhou, Changhe; Feng, Jijun; Ru, Huayi; Zheng, Jiangjun

    2008-08-01

    The usual beam splitter of multilayer-coated film with a wideband spectrum is not easy to achieve. We describe the realization of a wideband transmission two-port beam splitter based on a binary fused-silica phase grating. To achieve high efficiency and equality in the diffracted 0th and -1st orders, the grating profile parameters are optimized using rigorous coupled-wave analysis at a wavelength of 1550 nm. Holographic recording and the inductively coupled plasma dry etching technique are used to fabricate the fused-silica beam splitter grating. The measured efficiency of (45% x 2) = 90% diffracted into the both orders can be obtained with the fabricated grating under Littrow mounting. The physical mechanism of such a wideband two-port beam splitter grating can be well explained by the modal method based on two-beam interference of the modes excited by the incident wave. With the high damage threshold, low coefficient of thermal expansion, and wideband high efficiency, the presented beam splitter etched in fused silica should be a useful optical element for a variety of practical applications.

  7. Evaluation of Beam Loss and Energy Depositions for a Possible Phase II Design for LHC Collimation

    International Nuclear Information System (INIS)

    Lari, L.; Assmann, R.; Bracco, C.; Brugger, M.; Cerutti, F.; Doyle, E.; Ferrari, A.; Keller, L.; Lundgren, S.; Markiewicz, Thomas W.; Mauri, M.; Redaelli, S.; Sarchiapone, L.; Smith, J.; Vlachoudis, V.; Weiler, T.

    2011-01-01

    The LHC beams are designed to have high stability and to be stored for many hours. The nominal beam intensity lifetime is expected to be of the order of 20h. The Phase II collimation system has to be able to handle particle losses in stable physics conditions at 7 TeV in order to avoid beam aborts and to allow correction of parameters and restoration to nominal conditions. Monte Carlo simulations are needed in order to evaluate the behavior of metallic high-Z collimators during operation scenarios using a realistic distribution of losses, which is a mix of the three limiting halo cases. Moreover, the consequences in the IR7 insertion of the worst (case) abnormal beam loss are evaluated. The case refers to a spontaneous trigger of the horizontal extraction kicker at top energy, when Phase II collimators are used. These studies are an important input for engineering design of the collimation Phase II system and for the evaluation of their effect on adjacent components. The goal is to build collimators that can survive the expected conditions during LHC stable physics runs, in order to avoid quenches of the SC magnets and to protect other LHC equipments.

  8. Evaluation of Beam Losses And Energy Deposition for a Possible Phase II Design for LHC Collimation

    International Nuclear Information System (INIS)

    Lari, L.; Bracco, C.; Assmann, R.W.; Brugger, M.; Cerutti, F.; Ferrari, A.; Mauri, M.; Redaelli, S.; Sarchiapone, L.; Vlachoudis, V.; Weiler, T.; Doyle, J.E.; Keller, L.; Lundgren, S.A.; Markiewicz, T.W.; Smith, J.C.

    2011-01-01

    The Large Hadron Collider (LHC) beams are designed to have high stability and to be stored for many hours. The nominal beam intensity lifetime is expected to be of the order of 20h. The Phase II collimation system has to be able to handle particle losses in stable physics conditions at 7 TeV in order to avoid beam aborts and to allow correction of parameters and restoration to nominal conditions. Monte Carlo simulations are needed in order to evaluate the behavior of metallic high-Z collimators during operation scenarios using a realistic distribution of losses, which is a mix of the three limiting halo cases. Moreover, the consequences in the IR7 insertion of the worst (case) abnormal beam loss are evaluated. The case refers to a spontaneous trigger of the horizontal extraction kicker at top energy, when Phase II collimators are used. These studies are an important input for engineering design of the collimation Phase II system and for the evaluation of their effect on adjacent components. The goal is to build collimators that can survive the expected conditions during LHC stable physics runs, in order to avoid quenches of the SC magnets and to protect other LHC equipments.

  9. Measuring Dirac CP-violating phase with intermediate energy beta beam facility

    Science.gov (United States)

    Bakhti, P.; Farzan, Y.

    2014-02-01

    Taking the established nonzero value of , we study the possibility of extracting the Dirac CP-violating phase by a beta beam facility with a boost factor . We compare the performance of different setups with different baselines, boost factors, and detector technologies. We find that an antineutrino beam from He decay with a baseline of km has a very promising CP-discovery potential using a 500 kton water Cherenkov detector. Fortunately this baseline corresponds to the distance between FermiLAB to Sanford underground research facility in South Dakota.

  10. Beam position monitor for energy recovered linac beams

    Energy Technology Data Exchange (ETDEWEB)

    Powers, Thomas; Evtushenko, Pavel

    2017-06-06

    A method of determining the beam position in an energy recovered linac (ERL). The method makes use of in phase and quadrature (I/Q) demodulation techniques to separate the pickup signal generated by the electromagnetic fields generated by the first and second pass beam in the energy recovered linac. The method includes using analog or digital based I/Q demodulation techniques in order to measure the relative amplitude of the signals from a position sensitive beam pickup such as a button, strip line or microstripline beam position monitor.

  11. PBFA [Particle Beam Fusion Accelerator] II: The pulsed power characterization phase

    International Nuclear Information System (INIS)

    Martin, T.H.; Turman, B.N.; Goldstein, S.A.

    1987-01-01

    The Particle Beam Fusion Accelerator II, PBFA II, is now the largest pulsed power device in operation. This paper summarizes its first year and a half of operation for the Department of Energy (DOE) Inertial Confinement Fusion (ICF) program. Thirty-six separate modules provide 72 output pulses that combine to form a 100 TW output pulse at the accelerator center. PBFA II was successfully test fired for the first time on December 11, 1985. This test completed the construction phase (Phase 1) within the expected schedule and budget. The accelerator checkout phase then started (Phase 2). The first priority during checkout was to bring the Phase 1 subsystems into full operation. The accelerator was first tested to determine overall system performance. Next, subsystems that were not performing adequately were modified. The accelerator is now being used for ion diode studies. 32 refs

  12. Verification and application of beam steering Phased Array UT technique for complex structures

    International Nuclear Information System (INIS)

    Yamamoto, Setsu; Miura, Takahiro; Semboshi, Jun; Ochiai, Makoto; Mitsuhashi, Tadahiro; Adachi, Hiroyuki; Yamamoto, Satoshi

    2013-01-01

    Phased Array Ultrasonic Testing (PAUT) techniques for complex geometries are greatly progressing. We developed an immersion PAUT which is suitable for complex surface profiles such as nozzles and deformed welded areas. Furthermore, we have developed a shape adaptive beam steering technique for 3D complex surface structures with conventional array probe and flexible coupling gel which makes the immersion beam forming technique usable under dry conditions. This system consists of 3 steps. Step1 is surface profile measurement which based on 3D Synthesis Aperture Focusing Technique (SAFT), Step2 is delay law calculation which could take into account the measured 3D surface profiles and steer a shape adjusted ultrasonic beam, Step3 is shape adjusted B-scope construction. In this paper, verification results of property of this PAUT system using R60 curved specimen and nozzle shaped specimen which simulated actual BWR structure. (author)

  13. Geometrical Optics of Beams with Vortices: Berry Phase and Orbital Angular Momentum Hall Effect

    International Nuclear Information System (INIS)

    Bliokh, Konstantin Yu.

    2006-01-01

    We consider propagation of a paraxial beam carrying the spin angular momentum (polarization) and intrinsic orbital angular momentum (IOAM) in a smoothly inhomogeneous isotropic medium. It is shown that the presence of IOAM can dramatically enhance and rearrange the topological phenomena that previously were considered solely in connection to the polarization of transverse waves. In particular, the appearance of a new type of Berry phase that describes the parallel transport of the beam structure along a curved ray is predicted. We derive the ray equations demonstrating the splitting of beams with different values of IOAM. This is the orbital angular momentum Hall effect, which resembles the Magnus effect for optical vortices. Unlike the spin Hall effect of photons, it can be much larger in magnitude and is inherent to waves of any nature. Experimental means to detect the phenomena are discussed

  14. PSB beam longitudinal blow-up by phase modulation with the digital LLRF prototype system

    CERN Document Server

    Angoletta, M E; Butterworth, A; Findlay, A; Jaussi, M; Leinonen, P; Molendijk, J; Sanchez-Quesada, J

    2014-01-01

    The PSB will be upgraded to a new, Digital Low-Level RF (DLLRF) system in 2014 at the injectors’ restart after LS1. This DLLRF is an evolution of that successfully deployed in LEIR and comprises new hardware, software and implementation strategies. Machine development studies have been carried out in the PSB over recent years with the existing LEIR-style hardware installed in PSB ring four. These studies have allowed testing approaches and validating implementation strategies. This note focuses on a series of MDs carried out during the 2011 run where a new implementation of the longitudinal beam blow-up obtained by phase modulation was tested. Test results and effects on the beam are show for a CNGS-type beam. Finally, an overview is given of the final longitudinal blow-up implementation planned with the new hardware, which will be operationally deployed in 2014.

  15. Geometrical optics of beams with vortices: Berry phase and orbital angular momentum Hall effect.

    Science.gov (United States)

    Bliokh, Konstantin Yu

    2006-07-28

    We consider propagation of a paraxial beam carrying the spin angular momentum (polarization) and intrinsic orbital angular momentum (IOAM) in a smoothly inhomogeneous isotropic medium. It is shown that the presence of IOAM can dramatically enhance and rearrange the topological phenomena that previously were considered solely in connection to the polarization of transverse waves. In particular, the appearance of a new type of Berry phase that describes the parallel transport of the beam structure along a curved ray is predicted. We derive the ray equations demonstrating the splitting of beams with different values of IOAM. This is the orbital angular momentum Hall effect, which resembles the Magnus effect for optical vortices. Unlike the spin Hall effect of photons, it can be much larger in magnitude and is inherent to waves of any nature. Experimental means to detect the phenomena are discussed.

  16. Direct generation of abruptly focusing vortex beams using a 3/2 radial phase-only pattern.

    Science.gov (United States)

    Davis, Jeffrey A; Cottrell, Don M; Zinn, Jonathan M

    2013-03-20

    Abruptly focusing Airy beams have previously been generated using a radial cubic phase pattern that represents the Fourier transform of the Airy beam. The Fourier transform of this pattern is formed using a system length of 2f, where f is the focal length of the Fourier transform lens. In this work, we directly generate these abruptly focusing Airy beams using a 3/2 radial phase pattern encoded onto a liquid crystal display. The resulting optical system is much shorter. In addition, we can easily produce vortex patterns at the focal point of these beams. Experimental results match theoretical predictions.

  17. A theoretically exact reconstruction algorithm for helical cone-beam differential phase-contrast computed tomography

    International Nuclear Information System (INIS)

    Li Jing; Sun Yi; Zhu Peiping

    2013-01-01

    Differential phase-contrast computed tomography (DPC-CT) reconstruction problems are usually solved by using parallel-, fan- or cone-beam algorithms. For rod-shaped objects, the x-ray beams cannot recover all the slices of the sample at the same time. Thus, if a rod-shaped sample is required to be reconstructed by the above algorithms, one should alternately perform translation and rotation on this sample, which leads to lower efficiency. The helical cone-beam CT may significantly improve scanning efficiency for rod-shaped objects over other algorithms. In this paper, we propose a theoretically exact filter-backprojection algorithm for helical cone-beam DPC-CT, which can be applied to reconstruct the refractive index decrement distribution of the samples directly from two-dimensional differential phase-contrast images. Numerical simulations are conducted to verify the proposed algorithm. Our work provides a potential solution for inspecting the rod-shaped samples using DPC-CT, which may be applicable with the evolution of DPC-CT equipments. (paper)

  18. Two-dimensional analytic modeling of acoustic diffraction for ultrasonic beam steering by phased array transducers.

    Science.gov (United States)

    Wang, Tiansi; Zhang, Chong; Aleksov, Aleksandar; Salama, Islam; Kar, Aravinda

    2017-04-01

    Phased array ultrasonic transducers enable modulating the focal position of the acoustic waves, and this capability is utilized in many applications, such as medical imaging and non-destructive testing. This type of transducers also provides a mechanism to generate tilted wavefronts in acousto-optic deflectors to deflect laser beams for high precision advanced laser material processing. In this paper, a theoretical model is presented for the diffraction of ultrasonic waves emitted by several phased array transducers into an acousto-optic medium such as TeO 2 crystal. A simple analytic expression is obtained for the distribution of the ultrasonic displacement field in the crystal. The model prediction is found to be in good agreement with the results of a numerical model that is based on a non-paraxial multi-Gaussian beam (NMGB) model. Published by Elsevier B.V.

  19. Space charge and beam stability issues of the Fermilab proton driver in Phase I

    Energy Technology Data Exchange (ETDEWEB)

    K. Y. Ng

    2001-08-24

    Issues concerning beam stability of the proposed Fermilab Proton Driver are studied in its Phase I. Although the betatron tune shifts are dominated by space charge, these shifts are less than 0.25 and will therefore not drive the symmetric and antisymmetric modes of the beam envelope into instability. The longitudinal space charge force is large and inductive inserts may be needed to compensate for the distortion of the rf potential. Although the longitudinal impedance is space charge dominated, it will not drive any microwave instability, unless the real part of the impedance coming from the inductive inserts and wall resistivity of the beam tube are large enough. The design of the beam tube is therefore very important in order to limit the flow of eddy current and keep wall resistivity low. The transverse impedance is also space charge dominated. With the Proton Driver operated at an imaginary transition gamma, however, Landau damping will never be canceled and beam stability can be maintained with negative chromaticities.

  20. Interplay between topological phase and self-acceleration in a vortex symmetric Airy beam.

    Science.gov (United States)

    Fang, Zhao-Xiang; Chen, Yue; Ren, Yu-Xuan; Gong, Lei; Lu, Rong-De; Zhang, An-Qi; Zhao, Hong-Ze; Wang, Pei

    2018-03-19

    Photons in an optical vortex usually carry orbital angular momentum, which boosts the application of the micro-rotation of absorbing particles and quantum information encoding. Such photons propagate along a straight line in free space or follow a curved trace once guided by an optical fiber. Teleportation of an optical vortex using a beam with non-diffraction and self-healing is quite challenging. We demonstrate the manipulation of the propagation trace of an optical vortex with a symmetric Airy beam (SAB) and found that the SAB experiences self-rotation with the implementation of a topological phase structure of coaxial vortex. Slight misalignment of the vortex and the SAB enables the guiding of the vortex into one of the self-accelerating channels. Multiple off-axis vortices embedded in SAB are also demonstrated to follow the trajectory of the major lobe for the SAB beam. The Poynting vector for the beams proves the direction of the energy flow corresponding to the intensity distribution. Hence, we anticipate that the proposed vortex symmetric Airy beam (VSAB) will provide new possibilities for optical manipulation and optical communication.

  1. Photoacoustic Soot Spectrometer (PASS) Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Dubey, M [Los Alamos National Laboratory; Springston, S [Brookhaven National Laboratory; Koontz, A [Pacific Northwest National Laboratory; Aiken, A [Los Alamos National Laboratory

    2013-01-17

    The photoacoustic soot spectrometer (PASS) measures light absorption by aerosol particles. As the particles pass through a laser beam, the absorbed energy heats the particles and in turn the surrounding air, which sets off a pressure wave that can be detected by a microphone. The PASS instruments deployed by ARM can also simultaneously measure the scattered laser light at three wavelengths and therefore provide a direct measure of the single-scattering albedo. The Operator Manual for the PASS-3100 is included here with the permission of Droplet Measurement Technologies, the instrument’s manufacturer.

  2. Spiral phase plates for the generation of high-order Laguerre-Gaussian beams with non-zero radial index

    Science.gov (United States)

    Ruffato, G.; Carli, M.; Massari, M.; Romanato, F.

    2015-03-01

    The work of design, fabrication and characterization of spiral phase plates for the generation of Laguerre-Gaussian (LG) beams with non-null radial index is presented. Samples were fabricated by electron beam lithography on polymethylmethacrylate layers over glass substrates. The optical response of these phase optical elements was measured and the purity of the experimental beams was investigated in terms of Laguerre-Gaussian modes contributions. The farfield intensity pattern was compared with theoretical models and numerical simulations, while the expected phase features were confirmed by interferometric analyses. The high quality of the output beams confirms the applicability of these phase plates for the generation of high-order Laguerre-Gaussian beams. A novel application consisting in the design of computer-generated holograms encoding information for light beams carrying phase singularities is shown. A numerical code based on iterative Fourier transform algorithm has been developed for the computation of the phase pattern of phase-only diffractive optical element for illumination under LG beams. Numerical analysis and preliminary experimental results confirm the applicability of these devices as high-security optical elements.

  3. Epitaxial growth and new phase of single crystal Dy by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Yang, Kai-Yueh; Homma, Hitoshi; Schuller, I.K.

    1987-09-01

    We have grown two novel epitaxial phases of dysprosium (Dy) on vanadium (V) by molecular beam epitaxy technique. Surface and bulk structures are studied by in-situ reflection high energy electron diffraction (RHEED) and x-ray diffraction techniques. The new hcp phases are ∼4% expanded uniformly in-plane (0001), and ∼9% and ∼4% expanded out of plane along the c-axes for non-interrupted and interrupted deposition case, respectively. We also observed (2 x 2), (3 x 3), and (4 x 4) Dy surface reconstruction patterns and a series of transitions as the Dy film thickness increases. 12 refs., 3 figs

  4. Phase stability of zirconium oxide films during focused ion beam milling

    Science.gov (United States)

    Baxter, Felicity; Garner, Alistair; Topping, Matthew; Hulme, Helen; Preuss, Michael; Frankel, Philipp

    2018-06-01

    Focused ion beam (FIB) is a widely used technique for preparation of electron transparent samples and so it is vital to understand the potential for introduction of FIB-induced microstructural artefacts. The bombardment of both Xe+ and Ga+ ions is observed to cause extensive monoclinic to tetragonal phase transformation in ZrO2 corrosion films, however, this effect is diminished with reduced energy and is not observed below 5 KeV. This study emphasises the importance of careful FIB sample preparation with a low energy cleaning step, and also gives insight into the stabilisation mechanism of the tetragonal phase during oxidation.

  5. Phase-space database for external beam radiotherapy. Summary report of a consultants' meeting

    International Nuclear Information System (INIS)

    Capote, R.; Jeraj, R.; Ma, C.M.; Rogers, D.W.O.; Sanchez-Doblado, F.; Sempau, J.; Seuntjens, J.; Siebers, J.V.

    2006-01-01

    A summary is given of a Consultants' Meeting assembled to discuss and recommend actions and activities to prepare a Phase-space Database for External Beam Radiotherapy. The new database should serve to disseminate phase-space data of those accelerators and 60 Co units used in radiotherapy through the compilation of existing data that have been properly validated. Both the technical discussions and the resulting work plan are described, along with the detailed recommendations for implementation. The meeting was jointly organized by NAPC-Nuclear Data Section and NAHU-Dosimetry and Medical Radiation Physics Section. (author)

  6. Propagation-invariant vectorial Bessel beams by use of sub wavelength quantized Pancharatnam-Berry phase optics

    International Nuclear Information System (INIS)

    Niv, A.; Biener, G.; Kleiner, V.; Hasman, E.

    2004-01-01

    Full Text:Propagation-invariant scalar fields have been extensively studied both theoretically and experimentally, since they were proposed by Durnin et al. These fields were employed in applications such as optical tweezers and for transport and guiding of microspheres. Although there has recently been considerable theoretical interest in propagation-invariant vectorial beams, experimental studies of such beams have remained somewhat limited. One of the most interesting types of propagation-invariant vectorial beam is the linearly polarized axially symmetric beam (LPASB) [l]. Recently, we introduced and experimentally demonstrated propagation-invariant vectorial Bessel beams with linearly polarized axial symmetry based on quantized Pancharatnam-Berry phase optical elements (QPBOEs) [21 and an axicon. QP-BOEs utilize the geometric phase that accompanies space-variant polarization manipulations to achieve a desired phase modification [31. To test our approach we formed QPBOEs with different polarization orders as computer-generated space-variant sub wavelength gratings upon GaAs wafers for use with 10.6 micron laser radiation. The resultant beams were also transmitted through a polarizer that produced a unique propagation-invariant scalar beam. This beam has a propeller-shaped intensity pattern that can be rotated by simple rotation of the polarizer. We therefore have demonstrated the formation of a vectorial Bessel beam by using simple, lightweight thin elements and exploited that beam to perform a controlled rotation of a propeller-shaped intensity pattern that can be suitable for optical tweezers

  7. Effect of dipole-quadrupole Robinson mode coupling upon the beam response to radio-frequency phase noise

    Directory of Open Access Journals (Sweden)

    R. A. Bosch

    2006-09-01

    Full Text Available In an electron storage ring, coupling between dipole and quadrupole Robinson oscillations modifies the spectrum of longitudinal beam oscillations driven by radio-frequency (rf generator phase noise. In addition to the main peak at the resonant frequency of the coupled dipole Robinson mode, another peak occurs at the resonant frequency of the coupled quadrupole mode. To describe these peaks analytically for a quadratic synchrotron potential, we include the dipole and quadrupole modes when calculating the beam response to generator noise. We thereby obtain the transfer function from generator-noise phase modulation to beam phase modulation with and without phase feedback. For Robinson-stable bunches confined in a synchrotron potential with a single minimum, the calculated transfer function agrees with measurements at the Aladdin 800-MeV electron storage ring. The transfer function is useful in evaluating phase feedback that suppresses Robinson oscillations in order to obtain quiet operation of an infrared beam line.

  8. Spiral phase plates with radial discontinuities for the generation of multiring orbital angular momentum beams: fabrication, characterization, and application

    Science.gov (United States)

    Ruffato, Gianluca; Massari, Michele; Carli, Marta; Romanato, Filippo

    2015-11-01

    A design of spiral phase plates for the generation of multiring beams carrying orbital angular momentum (OAM) is presented. Besides the usual helical profile, these phase plates present radial π-discontinuities in correspondence of the zeros of the associated Laguerre polynomials. Samples were fabricated by electron beam lithography over glass substrates coated with a polymethylmethacrylate resist layer. The optical response was analyzed and the purity of the generated beams was investigated in terms of Laguerre-Gaussian modes contributions. The far-field intensity pattern was compared with theoretical models and numerical simulations, while the expected phase features were confirmed by interferometric analysis with a Mach-Zehnder setup. The high quality of the output beams confirms the applicability of these phase plates for the generation of high-order OAM beams with nonzero radial index. An application consisting of the design of computer-generated holograms encoding information for light beams carrying phase singularities is presented and described. A numerical code based on an iterative Fourier transform algorithm has been developed for the computation of phase-only diffractive optical element for illumination under OAM beams. Numerical analysis and preliminary experimental results confirm the applicability of these devices as high-security optical elements for anticounterfeiting applications.

  9. Structure-phase states evolution in Al-Si alloy under electron-beam treatment and high-cycle fatigue

    International Nuclear Information System (INIS)

    Konovalov, Sergey; Alsaraeva, Krestina; Gromov, Victor; Semina, Olga; Ivanov, Yurii

    2015-01-01

    By methods of scanning and transmission electron diffraction microscopy the analysis of structure-phase states and defect substructure of silumin subjected to high-intensity electron beam irradiation in various regimes and subsequent fatigue loading up to failure was carried out. It is revealed that the sources of fatigue microcracks are silicon plates of micron and submicron size are not soluble in electron beam processing. The possible reasons of the silumin fatigue life increase under electron-beam treatment are discussed

  10. Compensation for the phase-type spatial periodic modulation of the near-field beam at 1053 nm

    Science.gov (United States)

    Gao, Yaru; Liu, Dean; Yang, Aihua; Tang, Ruyu; Zhu, Jianqiang

    2017-10-01

    A phase-only spatial light modulator is used to provide and compensate for the spatial periodic modulation (SPM) of the near-field beam at the near infrared at 1053nm wavelength with an improved iterative weight-based method. The transmission characteristics of the incident beam has been changed by a spatial light modulator (SLM) to shape the spatial intensity of the output beam. The propagation and reverse propagation of the light in free space are two important processes in the iterative process. The based theory is the beam angular spectrum transmit formula (ASTF) and the principle of the iterative weight-based method. We have made two improvements to the originally proposed iterative weight-based method. We select the appropriate parameter by choosing the minimum value of the output beam contrast degree and use the MATLAB built-in angle function to acquire the corresponding phase of the light wave function. The required phase that compensates for the intensity distribution of the incident SPM beam is iterated by this algorithm, which can decrease the magnitude of the SPM of the intensity on the observation plane. The experimental results show that the phase-type SPM of the near-field beam is subject to a certain restriction. We have also analyzed some factors that make the results imperfect. The experiment results verifies the possible applicability of this iterative weight-based method to compensate for the SPM of the near-field beam.

  11. The Gaussian beam mode analysis of classical phase aberrations in diffraction-limited optical systems

    Science.gov (United States)

    Trappe, Neil; Murphy, J. Anthony; Withington, Stafford

    2003-07-01

    Gaussian beam mode analysis (GBMA) offers a more intuitive physical insight into how light beams evolve as they propagate than the conventional Fresnel diffraction integral approach. In this paper we illustrate that GBMA is a computationally efficient, alternative technique for tracing the evolution of a diffracting coherent beam. In previous papers we demonstrated the straightforward application of GBMA to the computation of the classical diffraction patterns associated with a range of standard apertures. In this paper we show how the GBMA technique can be expanded to investigate the effects of aberrations in the presence of diffraction by introducing the appropriate phase error term into the propagating quasi-optical beam. We compare our technique to the standard diffraction integral calculation for coma, astigmatism and spherical aberration, taking—for comparison—examples from the classic text 'Principles of Optics' by Born and Wolf. We show the advantages of GBMA for allowing the defocusing of an aberrated image to be evaluated quickly, which is particularly important and useful for probing the consequences of astigmatism and spherical aberration.

  12. The Gaussian beam mode analysis of classical phase aberrations in diffraction-limited optical systems

    International Nuclear Information System (INIS)

    Trappe, Neil; Murphy, J Anthony; Withington, Stafford

    2003-01-01

    Gaussian beam mode analysis (GBMA) offers a more intuitive physical insight into how light beams evolve as they propagate than the conventional Fresnel diffraction integral approach. In this paper we illustrate that GBMA is a computationally efficient, alternative technique for tracing the evolution of a diffracting coherent beam. In previous papers we demonstrated the straightforward application of GBMA to the computation of the classical diffraction patterns associated with a range of standard apertures. In this paper we show how the GBMA technique can be expanded to investigate the effects of aberrations in the presence of diffraction by introducing the appropriate phase error term into the propagating quasi-optical beam. We compare our technique to the standard diffraction integral calculation for coma, astigmatism and spherical aberration, taking - for comparison - examples from the classic text 'Principles of Optics' by Born and Wolf. We show the advantages of GBMA for allowing the defocusing of an aberrated image to be evaluated quickly, which is particularly important and useful for probing the consequences of astigmatism and spherical aberration

  13. Low-level feedback control for the phase regulation of CLIC Drive Beam Klystrons

    CERN Document Server

    AUTHOR|(SzGeCERN)752526

    2015-01-01

    The requirement of luminosity loss below 1% raises tight tolerances for the phase and power stability of the CLIC drive beam (DB) klystrons and consequently for the high voltage pulse ripple of the modulators. A low-level RF (LLRF) feedback system needs to be developed and combined with the modulator in order to guarantee the phase and amplitude tolerances. To this aim, three feedback control strategies were investigated, i) Proportional Integral (PI) controller, ii) Linear Quadratic Integral Regulator (LQI) and iii) Model Predictive Controller (MPC). The klystron, as well as the incident phase noise were modelled and used for the design and evaluation of the controllers. First simulation results are presented along with future steps and directions.

  14. Phase mixing of transverse oscillations in the linear and nonlinear regimes for IFR relativistic electron beam propagation

    International Nuclear Information System (INIS)

    Shokair, I.R.

    1991-01-01

    Phase mixing of transverse oscillations changes the nature of the ion hose instability from an absolute to a convective instability. The stronger the phase mixing, the faster an electron beam reaches equilibrium with the guiding ion channel. This is important for long distance propagation of relativistic electron beams where it is desired that transverse oscillations phase mix within a few betatron wavelengths of injection and subsequently an equilibrium is reached with no further beam emittance growth. In the linear regime phase mixing is well understood and results in asymptotic decay of transverse oscillations as 1/Z 2 for a Gaussian beam and channel system, Z being the axial distance measured in betatron wavelengths. In the nonlinear regime (which is likely mode of propagation for long pulse beams) results of the spread mass model indicate that phase mixing is considerably weaker than in the regime. In this paper we consider this problem of phase mixing in the nonlinear regime. Results of the spread mass model will be shown along with a simple analysis of phase mixing for multiple oscillator models. Particle simulations also indicate that phase mixing is weaker in nonlinear regime than in the linear regime. These results will also be shown. 3 refs., 4 figs

  15. Angular beam width of a slit-diffracted wave with noncollinear group and phase velocities

    International Nuclear Information System (INIS)

    Lock, Edwin H

    2012-01-01

    Taking magnetostatic surface wave diffraction as an example, this paper theoretically investigates the 2D diffraction pattern arising in the far-field region of a ferrite slab in the case of a plane wave with noncollinear group and phase velocities incident on a wide, arbitrarily oriented slit in an opaque screen. A universal analytical formula for the angular width of a diffracted beam is derived, which is valid for magnetostatic and other types of waves in anisotropic media and structures (including metamaterials) in 2D geometries. It is shown that the angular width of a diffracted beam in an anisotropic medium can not only take values greater or less than λ 0 /D (where λ 0 is the incident wavelength, and D is the slit width), but can also be zero under certain conditions. (methodological notes)

  16. Modeling of SBS Phase Conjugation in Multimode Step Index Fibers

    National Research Council Canada - National Science Library

    Spring, Justin B

    2008-01-01

    ... limited, double-pass high-power amplifiers or coherent beam combination. Little modeling of such a fiber-based phase-conjugator has been done, making it difficult to make decisions about the right fiber to use...

  17. Feasibility study of multi-pass respiratory-gated helical tomotherapy of a moving target via binary MLC closure

    Science.gov (United States)

    Kim, Bryan; Chen, Jeff; Kron, Tomas; Battista, Jerry

    2010-11-01

    Gated radiotherapy of lung lesions is particularly complex for helical tomotherapy, due to the simultaneous motions of its three subsystems (gantry, couch and collimator). We propose a new way to implement gating for helical tomotherapy, namely multi-pass respiratory gating. In this method, gating is achieved by delivering only the beam projections that occur within a respiratory gating window, while blocking the rest of the beam projections by fully closing all collimator leaves. Due to the continuous couch motion, the planned beam projections must be delivered over multiple passes of radiation deliveries. After each pass, the patient couch is reset to its starting position, and the treatment recommences at a different phase of tumour motion to 'fill in' the previously blocked beam projections. The gating process may be repeated until the plan dose is delivered (full gating), or halted after a certain number of passes, with the entire remaining dose delivered in a final pass without gating (partial gating). The feasibility of the full gating approach was first tested for sinusoidal target motion, through experimental measurements with film and computer simulation. The optimal gating parameters for full and partial gating methods were then determined for various fractionation schemes through computer simulation, using a patient respiratory waveform. For sinusoidal motion, the PTV dose deviations of -29 to 5% observed without gating were reduced to range from -1 to 3% for a single fraction, with a 4 pass full gating. For a patient waveform, partial gating required fewer passes than full gating for all fractionation schemes. For a single fraction, the maximum allowed residual motion was only 4 mm, requiring large numbers of passes for both full (12) and partial (7 + 1) gating methods. The number of required passes decreased significantly for 3 and 30 fractions, allowing residual motion up to 7 mm. Overall, the multi-pass gating technique was shown to be a promising

  18. Feasibility study of multi-pass respiratory-gated helical tomotherapy of a moving target via binary MLC closure

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bryan; Chen, Jeff; Battista, Jerry [London Regional Cancer Program, London Health Sciences Centre, London, ON (Canada); Kron, Tomas, E-mail: bryan.kim@lhsc.on.c [Peter MacCallum Cancer Center, Melbourne (Australia)

    2010-11-21

    Gated radiotherapy of lung lesions is particularly complex for helical tomotherapy, due to the simultaneous motions of its three subsystems (gantry, couch and collimator). We propose a new way to implement gating for helical tomotherapy, namely multi-pass respiratory gating. In this method, gating is achieved by delivering only the beam projections that occur within a respiratory gating window, while blocking the rest of the beam projections by fully closing all collimator leaves. Due to the continuous couch motion, the planned beam projections must be delivered over multiple passes of radiation deliveries. After each pass, the patient couch is reset to its starting position, and the treatment recommences at a different phase of tumour motion to 'fill in' the previously blocked beam projections. The gating process may be repeated until the plan dose is delivered (full gating), or halted after a certain number of passes, with the entire remaining dose delivered in a final pass without gating (partial gating). The feasibility of the full gating approach was first tested for sinusoidal target motion, through experimental measurements with film and computer simulation. The optimal gating parameters for full and partial gating methods were then determined for various fractionation schemes through computer simulation, using a patient respiratory waveform. For sinusoidal motion, the PTV dose deviations of -29 to 5% observed without gating were reduced to range from -1 to 3% for a single fraction, with a 4 pass full gating. For a patient waveform, partial gating required fewer passes than full gating for all fractionation schemes. For a single fraction, the maximum allowed residual motion was only 4 mm, requiring large numbers of passes for both full (12) and partial (7 + 1) gating methods. The number of required passes decreased significantly for 3 and 30 fractions, allowing residual motion up to 7 mm. Overall, the multi-pass gating technique was shown to be a

  19. Numerical simulation of gas-solid two-phase flow in U-beam separator

    International Nuclear Information System (INIS)

    Zhou, X Y; Chen, X P; Dou, H S; Zhang, H Z; Ruan, J M

    2015-01-01

    Numerical simulation is carried out for gas-solid two-phase flow in a U-beam separator. In this study, the U-beam is altered with the inlet fins in order to improve the performance of the separator. The inlet fin angle of the separator are 30°, 35°, 40°, 45°, 50°, 55 ° and 60°. The governing equations are the Reynolds-Averaged Navier-Stokes equation with the standard k-ε model and the discrete phase model (DPM) describing the discrete two - phase flow as well as stochastic tracking model. Results show that the pressure drop deviation with fins is within 3% from those without fins. It is found that there is a maximum separation efficiency at the fin angle of 35°. Fin induces generation of a stagnation region which could collect particles and lead to change of vortical structures. The fin induced flow also causes the turbulent intensity inside the baffle to decrease to facilitate separation

  20. A technique for measuring an electron beam close-quote s longitudinal phase space with sub-picosecond resolution

    International Nuclear Information System (INIS)

    Crosson, E.R.; Berryman, K.W.; Richman, B.A.; Smith, T.I.; Swent, R.L.

    1996-01-01

    We have developed a technique for measuring the longitudinal phase space distribution of the Stanford Superconducting Accelerator close-quote s (SCA) electron beam which involves applying tomographic techniques to energy spectra taken as a function of the relative phase between the beam and the accelerating field, and optionally, as a function of the strength of a variable dispersion section in the system. The temporal profile of the beam obtained by projecting the inferred distribution onto the time axis is compared with that obtained from interferometric transition radiation measurements. copyright 1996 American Institute of Physics

  1. Effect of elemental composition of ion beam on the phase formation and surface strengthening of structural materials

    International Nuclear Information System (INIS)

    Avdienko, K.I.; Avdienko, A.A.; Kovalenko, I.A.

    2001-01-01

    The investigation results are reported on the influence of ion beam element composition on phase formation, wear resistance and microhardness of surface layers of titanium alloys VT-4 and VT-16 as well as stainless steel 12Kh18N10T implanted with nitrogen, oxygen and boron. It is stated that ion implantation into structural materials results in surface hardening and is directly dependent on element composition of implanted ion beam. The presence of oxygen in boron or nitrogen ion beams prevents the formation of boride and nitride phases thus decreasing a hardening effect [ru

  2. Analytical description of photon beam phase spaces in inverse Compton scattering sources

    Directory of Open Access Journals (Sweden)

    C. Curatolo

    2017-08-01

    Full Text Available We revisit the description of inverse Compton scattering sources and the photon beams generated therein, emphasizing the behavior of their phase space density distributions and how they depend upon those of the two colliding beams of electrons and photons. The main objective is to provide practical formulas for bandwidth, spectral density, brilliance, which are valid in general for any value of the recoil factor, i.e. both in the Thomson regime of negligible electron recoil, and in the deep Compton recoil dominated region, which is of interest for gamma-gamma colliders and Compton sources for the production of multi-GeV photon beams. We adopt a description based on the center of mass reference system of the electron-photon collision, in order to underline the role of the electron recoil and how it controls the relativistic Doppler/boost effect in various regimes. Using the center of mass reference frame greatly simplifies the treatment, allowing us to derive simple formulas expressed in terms of rms momenta of the two colliding beams (emittance, energy spread, etc. and the collimation angle in the laboratory system. Comparisons with Monte Carlo simulations of inverse Compton scattering in various scenarios are presented, showing very good agreement with the analytical formulas: in particular we find that the bandwidth dependence on the electron beam emittance, of paramount importance in Thomson regime, as it limits the amount of focusing imparted to the electron beam, becomes much less sensitive in deep Compton regime, allowing a stronger focusing of the electron beam to enhance luminosity without loss of mono-chromaticity. A similar effect occurs concerning the bandwidth dependence on the frequency spread of the incident photons: in deep recoil regime the bandwidth comes out to be much less dependent on the frequency spread. The set of formulas here derived are very helpful in designing inverse Compton sources in diverse regimes, giving a

  3. Analysis of ultrasonic beam profile due to change of elements' number for phased array transducer (part 2)

    International Nuclear Information System (INIS)

    Choi, Sang Woo; Lee, Joon Hyun

    1998-01-01

    The phased array offers many advantages and improvements over conventional single-element transducers such as the straight-beam and angle-beam. The advantages of array sensors for large structures are two folds; firstly, array transducers provide a method of rapid beam steering and sequential addressing of a large area of interest without requiring mechanical or manual scanning which is particularly important in real-time application. Secondly, array transducer provide a method of dynamic focusing, in which the focal length of the ultrasonic beam varies as the pulse propagates through the material. There are some parameters such as number, size, center to center space of elements to design phased array transducer. In previous study. the characteristics of beam steering and dynamic focusing had been simulated for ultrasonic SH-wave with varying the number of phased array transducer's element. In this study, the characteristic of beam steering for phased array transducer has been simulated for ultrasonic SH-wave on the basis of Huygen's principle with varying center to center space of elements. Ultrasonic beam directivity and focusing due to change of time delay of each element were discussed with varying center to center space of elements.

  4. Vecksler-Macmillan phase stability for neutral atoms accelerated by a laser beam

    Science.gov (United States)

    Mel'nikov, I. V.; Haus, J. W.; Kazansky, P. G.

    2003-05-01

    We use a Fokker-Planck equation to study the phenomenon of accelerating a neutral atom bunch by a chirped optical beam. This method enables us to obtain a semi-analytical solution to the problem in which a wide range of parameters can be studied. In addition it provides a simple physical interpretation where the problem is reduced to an analogous problem of charged particles accelerators, that is, the Vecksler-Macmillan principle of phase stability. A possible experimental scenario is suggested, which uses a photonic crystal fiber as the guiding medium.

  5. Simulating non-Kolmogorov turbulence phase screens based on equivalent structure constant and its influence on simulations of beam propagation

    Directory of Open Access Journals (Sweden)

    Ming Chen

    Full Text Available Gaussian distribution is used to describe the power law along the propagation path and phase screen of the non-Kolmogorov turbulence is proposed based on the equivalent refractive-index structure constants. Various simulations of Gaussian beam propagation in Kolmogorov and non-Kolmogorov turbulence are used for telling the difference between isotropic and anisotropic turbulence. The results imply that the non-Kolmogorov turbulence makes a great influence on the simulations via power law in spectrum and the number of phase screens. Furthermore, the influence is mainly reflected in light intensity and beam drift. Statistics suggest that when Gaussian beam propagate through single phase screen of non-Kolmogorov, maximum and uniformity of light intensity increase first and then decrease with power law, and beam drift firstly increases and then to stabilize. When Gaussian beam propagate through multiple phase screens, relative errors of beam drift decrease with the number of phase screens. And scintillation indices in non-Kolmogorov turbulence is larger than that in Kolmogorov turbulence when the number is small. When the number is big, the scintillation indices in non-Kolmogorov turbulence is smaller than that in Kolmogorov turbulence. The results shown in this paper demonstrate the effect of the non-Kolmogorov turbulence on laser atmospheric transmissions. Thus, this paper suggests a possible direction of the improvement of the laser transmission accuracy over a long distance through the atmosphere.

  6. Two-pass dual-energy CT imaging for simultaneous detection, characterization, and volume measurement of urinary stones with excretory-phase CT urography alone. A phantom study

    International Nuclear Information System (INIS)

    Takahashi, Satoru; Niikawa, Hidekazu; Shikata, Atsushi; Murakami, Emi; Tsunoda, Hiroshi; Yoshioka, Toshiaki; Yamamoto, Hiroshi; Itoh, Toshihide; Tsujihata, Masao

    2013-01-01

    The purpose of this study was to evaluate if two-pass dual-energy CT imaging - id est (i.e.), simultaneous three-material and two-material decomposition analysis - can depict and characterize urinary stones in various concentrations of iodine solution in vitro. Twelve urinary stones were scanned with a dual-source CT scanner. First, each stone (in a saline-filled tube) underwent single- and dual-energy mode CT scans in order to measure the volume of the stone. Each stone was then placed in various concentrations of contrast medium and scanned in dual-energy mode to calculate its volume via three-material decomposition analysis. Two-pass dual-energy CT imaging analysis software for the Matlab environment, which was developed specifically to process simultaneous three-material and two-material decomposition, was applied to characterize and calculate the volume of each stone. Although the virtual non-contrast images from three-material decomposition analysis clearly visualized all of the stones in contrast medium with up to 80 mgI/mL, the volumes of the uric acid stones were overestimated. Two-pass dual-energy CT imaging was able to depict and characterize non-uric-acid stones in diluted contrast medium with up to 80 mgI/mL, whereas uric acid stones were correctly evaluated in diluted contrast medium with 40 mgI/mL or less. Two-pass dual-energy CT imaging is able to depict and characterize urinary stones in contrast medium. (author)

  7. Temporal analysis of laser beam propagation in the atmosphere using computer-generated long phase screens.

    Science.gov (United States)

    Dios, Federico; Recolons, Jaume; Rodríguez, Alejandro; Batet, Oscar

    2008-02-04

    Temporal analysis of the irradiance at the detector plane is intended as the first step in the study of the mean fade time in a free optical communication system. In the present work this analysis has been performed for a Gaussian laser beam propagating in the atmospheric turbulence by means of computer simulation. To this end, we have adapted a previously known numerical method to the generation of long phase screens. The screens are displaced in a transverse direction as the wave is propagated, in order to simulate the wind effect. The amplitude of the temporal covariance and its power spectrum have been obtained at the optical axis, at the beam centroid and at a certain distance from these two points. Results have been worked out for weak, moderate and strong turbulence regimes and when possible they have been compared with theoretical models. These results show a significant contribution of beam wander to the temporal behaviour of the irradiance, even in the case of weak turbulence. We have also found that the spectral bandwidth of the covariance is hardly dependent on the Rytov variance.

  8. Optimizing the average longitudinal phase of the beam in the SLC linac

    International Nuclear Information System (INIS)

    Bane, K.L.F.

    1989-09-01

    The relation of the beam's average linac phase, φ 0 , to the final energy spectrum in the SLC linac has been studied by many people over the years, with much of the work left unpublished. In this note we perform a somewhat thorough in vestigation of the problem. First we describe the calculation method, and discuss some common features of the energy spectrum. Then we calculate the value of φ 0 that minimizes δ rms for the conceivable range of bunch population and bunch lengths of the SLC linac. This is followed by luminosity calculations, including the sensitivity of luminosity to variations in φ 0 . Finally we suggest a practical method of implementing the proper phase setting on the real machine

  9. Complex 3D Vortex Lattice Formation by Phase-Engineered Multiple Beam Interference

    Directory of Open Access Journals (Sweden)

    Jolly Xavier

    2012-01-01

    Full Text Available We present the computational results on the formation of diverse complex 3D vortex lattices by a designed superposition of multiple plane waves. Special combinations of multiples of three noncoplanar plane waves with a designed relative phase shift between one another are perturbed by a nonsingular beam to generate various complex 3D vortex lattice structures. The formation of complex gyrating lattice structures carrying designed vortices by means of relatively phase-engineered plane waves is also computationally investigated. The generated structures are configured with both periodic as well as transversely quasicrystallographic basis, while these whirling complex lattices possess a long-range order of designed symmetry in a given plane. Various computational analytical tools are used to verify the presence of engineered geometry of vortices in these complex 3D vortex lattices.

  10. Dark GPC: extended nodal beam areas from binary-only phase

    DEFF Research Database (Denmark)

    Villangca, Mark Jayson; Bañas, Andrew Rafael; Palima, Darwin

    2016-01-01

    We show a simplified method of generating extended regions of destructive interference with near arbitrary shapes using the generalized phase contrast (GPC) method. For Gaussian input beams, GPC typically results in a 3×3× intensified user-defined input mask shape against a dark background....... In this work, we investigate conditions wherein GPC’s synthetic reference wave destructively interferes with what is typically the foreground pattern. Using alternate conditions for the input phase mask, the locations of light and darkness are interchanged with respect to typical GPC output mappings. We show...... and flexibility in the output shapes make dark GPC attractive for applications such as optical trapping of low-index particles or superresolution microscopy like stimulated emission depletion...

  11. Molecular beams

    International Nuclear Information System (INIS)

    Pendelbury, J.M.; Smith, K.F.

    1987-01-01

    Studies with directed collision-free beams of particles continue to play an important role in the development of modern physics and chemistry. The deflections suffered by such beams as they pass through electric and magnetic fields or laser radiation provide some of the most direct information about the individual constituents of the beam; the scattering observed when two beams intersect yields important data about the intermolecular forces responsible for the scattering. (author)

  12. TPG bus passes

    CERN Multimedia

    Staff Association

    2013-01-01

    The CERN Staff Association will stop selling TPG bus passes. All active and retired members of the CERN personnel will be able to purchase Unireso bus passes from the CERN Hostel - Building 39 (Meyrin site) from 1st February 2013. For more information: https://cds.cern.ch/journal/CERNBulletin/2013/04/Announcements/1505279?ln=en

  13. Synthesizing single-phase β-FeSi2 via ion beam irradiations of Fe/Si bilayers

    International Nuclear Information System (INIS)

    Milosavljevic, M.; Dhar, S.; Schaaf, P.; Bibic, N.; Lieb, K.P.

    2001-01-01

    This paper presents results on the direct synthesis of the β-FeSi 2 phase by ion beam mixing of Fe/Si bilayers with Xe ions. The influence of the substrate temperature, ion fluence and energy on the growth of this phase was investigated using Rutherford backscattering (RBS), X-ray diffraction (XRD) and conversion electron Moessbauer spectroscopy (CEMS). Complete growth of single-phase β-FeSi 2 was achieved by 205 keV Xe ion irradiation to a fluence of 2x10 16 ions/cm 2 at 600 deg. C. We propose a two-step reaction mechanism involving thermal and ion beam energy deposition

  14. Differential ion beam sputtering of segregated phases in aluminum casting alloys

    International Nuclear Information System (INIS)

    Nguyen, Chuong L.; Wirtz, Tom; Fleming, Yves; Metson, James B.

    2013-01-01

    Highlights: ► Novel combination of SIMS and SPM for accurate 3D chemical mapping. ► Different removal rates of metallurgical phases by ion beam. ► Faster oxidation rate of silicon vs. aluminum at room temperature in vacuum. - Abstract: Differential sputtering of materials is an important phenomenon in materials science with many implications. One of the practical applications of this phenomenon is the modification of the interface between a substrate and coating during sputter coating of materials. Aluminum casting alloys, as common materials in many applications, are suitable candidates to investigate this phenomenon due to their phase separated microstructures. Changes at the sample surface under ion bombardment can be characterized by a range of complimentary techniques. The novel SIMS–SPM instrument used here enables a thorough investigation into the evolution of topography and composition caused by ion beam sputtering. For the alloy examined in this work, the aluminum regions are removed faster than the silicon particles. The faster oxidation rate of silicon compared to aluminum in the exposed surface can also be deduced from this study.

  15. Numerical Analysis of Ultrasonic Beam Profile Due to the Change of the Number of Piezoelectric Elements for Phased Array Transducer

    International Nuclear Information System (INIS)

    Choi, Sang Woo; Lee, Joon Hyun

    1999-01-01

    A phased array is a multi-element piezoelectric device whose elements are individually excited by electric pulses at programmed delay time. One of the advantages of using phased array in nondestructive evaluation (NDE) application over conventional ultrasonic transducers is their great maneuverability of ultrasonic beam. There are some parameters such as the number and the size of the piezoelectric elements and the inter-element spacing of the elements to design phased array transducer. In this study, the characteristic of ultrasonic beam for phased array transducer due to the variation of the number of elements has been simulated for ultrasonic SH-wave on the basis of Huygen's principle. Ultrasonic beam directivity and focusing due to the change of time delay of each element were discussed due to the change of the number of piezoelectric elements. It was found that ultrasonic beam was much more spreaded and hence its sound pressure was decreased as steering angle of ultrasonic beam was increased. In addition, the ability of ultrasonic bean focusing decreased gradually with the increase of focal length at the same piezoelectric elements. However, the ability of beam focusing was improved as the number of consisting elements was increased

  16. Single-Phase LLCL-Filter-based Grid-Tied Inverter with Low-Pass Filter Based Capacitor Current Feedback Active damper

    DEFF Research Database (Denmark)

    Liu, Yuan; Wu, Weimin; Li, Yun

    2016-01-01

    The capacitor-current-feedback active damping method is attractive for high-order-filter-based high power grid-tied inverter when the grid impedance varies within a wide range. In order to improve the system control bandwidth and attenuate the high order grid background harmonics by using the quasi....... In this paper, a low pass filter is proposed to be inserted in the capacitor current feedback loop op LLCL-filter based grid-tied inverter together with a digital proportional and differential compensator. The detailed theoretical analysis is given. For verification, simulations on a 2kW/220V/10kHz LLCL...

  17. Phase transformations in nickel-aluminum alloys during ion beam mixing

    International Nuclear Information System (INIS)

    Eridon, J.; Rehn, L.; Was, G.

    1986-01-01

    The effect of ion beam mixing of nickel-aluminum alloys with 500 keV krypton ions has been investigated over a range of temperature, composition, ion dose, and post-irradiation thermal treatments. Samples were formed by alternate evaporation of layers of aluminum and nickel. A portion of these samples was subsequently annealed to form intermetallic compounds. Irradiations were performed at both room temperature and 80 0 K using the 2MV ion accelerator at Argonne National Laboratory. Phase transformations were observed during both in situ irradiations in the High Voltage Electron Microscope (HVEM) at Argonne, and also in subsequent analysis of an array of irradiated samples. Electron diffraction indicates the presence of metastable crystalline structures not present in the conventional nickel-aluminum phase diagram. Transformations occur at doses as low as 5 x 10 14 cm -2 and continue to develop as the irradiation progresses up to 2 x 10 16 cm -2 . Layer mixing is followed through Rutherford Backscattering analysis. Samples are also checked with x-rays and Electron Energy Loss Spectroscopy (EELS). A thermodynamic argument is presented to explain the phase transformations in terms of movements on a free energy diagram. This analysis explains the interesting paradox concerning the radiation hardness of the NiAl phase and the amorphous structure of mixed Ni-50% Al layers

  18. Passing and Catching in Rugby.

    Science.gov (United States)

    Namudu, Mike M.

    This booklet contains the fundamentals for rugby at the primary school level. It deals primarily with passing and catching the ball. It contains instructions on (1) holding the ball for passing, (2) passing the ball to the left--standing, (3) passing the ball to the left--running, (4) making a switch pass, (5) the scrum half's normal pass, (6) the…

  19. Single Shot Measurements of the 4-Dimensional Transverse Phase Space Distribution of Intense Ion Beams at the UNILAC at GSI

    CERN Document Server

    Groening, L

    2003-01-01

    The UNILAC is used as an injector for the synchrotron SIS. It is designed to fill the synchrotron up to its space charge limit. The upper limit for the useful beam emittance of the UNILAC is given by the finite acceptance of the SIS during the injection process. In order to remain within this acceptance the emittance growth during beam acceleration and transportation due to space charge effects must be minimized by applying an appropriate beam focusing. Therefore, the influence of the magnetic focusing strength on the beam emittance growth was investigated experimentally for different beam currents. Measurements of transverse phase space distributions were performed before and after the Alvarez accelerator with a periodic focusing channel, respectively. In order to perform such a wide parameter scan within a reasonable time with respect to machine stability, the pepper pot technique was applied. The pepper pot method allows for single-pulse measurements. For comparison several measurements using the slit-grid...

  20. SAFT-assisted sound beam focusing using phased arrays (PA-SAFT) for non-destructive evaluation

    Science.gov (United States)

    Nanekar, Paritosh; Kumar, Anish; Jayakumar, T.

    2015-04-01

    Focusing of sound has always been a subject of interest in ultrasonic non-destructive evaluation. An integrated approach to sound beam focusing using phased array and synthetic aperture focusing technique (PA-SAFT) has been developed in the authors' laboratory. The approach involves SAFT processing on ultrasonic B-scan image collected by a linear array transducer using a divergent sound beam. The objective is to achieve sound beam focusing using fewer elements than the ones required using conventional phased array. The effectiveness of the approach is demonstrated on aluminium blocks with artificial flaws and steel plate samples with embedded volumetric weld flaws, such as slag and clustered porosities. The results obtained by the PA-SAFT approach are found to be comparable to those obtained by conventional phased array and full matrix capture - total focusing method approaches.

  1. Numerical modeling of optical coherent transient processes with complex configurations - II. Angled beams with arbitrary phase modulations

    International Nuclear Information System (INIS)

    Chang Tiejun; Tian Mingzhen; Barber, Zeb W.; Randall Babbitt, Wm.

    2004-01-01

    This work is a continuation of the development of the theoretical model for optical coherent transient (OCT) processes with complex configurations. A theoretical model for angled beams with arbitrary phase modulation has been developed based on the model presented in our previous work for the angled beam geometry. A numerical tool has been devised to simulate the OCT processes involving angled beams with the frequency detuning, chirped, and phase-modulated laser pulses. The simulations for pulse shaping and arbitrary waveform generation (AWG) using OCT processes have been performed. The theoretical analysis of programming and probe schemes for pulse shaper and AWG is also presented including the discussions on the rephasing condition and the phase compensation. The results from the analysis, the simulation, and the experiment show very good agreement

  2. Simulation of 3-D radiation beam patterns propagated through a planar interface from ultrasonic phased array transducers.

    Science.gov (United States)

    Song, Sung-Jin; Kim, Chang-Hwan

    2002-05-01

    Phased array transducers are quite often mounted on solid wedges with specific angles in many practical ultrasonic inspections of thin plates phased array techniques with testing set-up, it is essential to have thorough understanding on the characteristics of radiation beam pattern produced in the interrogated medium. To address such a need, this paper proposes a systematic way to calculate full 3-D radiation beam patterns produced in the interrogated solid medium by phased array transducers mounted on a solid wedge. In order to investigate the characteristics of radiation beam patterns in steel, simulation is carried out for 7.5 MHz array transducers mounted on an acrylic wedge with the angle of 15.45 degrees with various of steering angles and/or focal planes.

  3. Phase II trial of proton beam accelerated partial breast irradiation in breast cancer

    International Nuclear Information System (INIS)

    Chang, Ji Hyun; Lee, Nam Kwon; Kim, Ja Young; Kim, Yeon-Joo; Moon, Sung Ho; Kim, Tae Hyun; Kim, Joo-Young; Kim, Dae Yong; Cho, Kwan Ho; Shin, Kyung Hwan

    2013-01-01

    Background and purpose: Here, we report the results of our phase II, prospective study of proton beam accelerated partial breast irradiation (PB-APBI) in patients with breast cancer after breast conserving surgery (BCS). Materials and methods: Thirty patients diagnosed with breast cancer were treated with PB-APBI using a single-field proton beam or two fields after BCS. The treatment dose was 30 cobalt gray equivalent (CGE) in six CGE fractions delivered once daily over five consecutive working days. Results: All patients completed PB-APBI. The median follow-up time was 59 months (range: 43–70 months). Of the 30 patients, none had ipsilateral breast recurrence or regional or distant metastasis, and all were alive at the last follow-up. Physician-evaluated toxicities were mild to moderate, except in one patient who had severe wet desquamation at 2 months that was not observed beyond 6 months. Qualitative physician cosmetic assessments of good or excellent were noted in 83% and 80% of the patients at the end of PB-APBI and at 2 months, respectively, and decreased to 69% at 3 years. A good or excellent cosmetic outcome was noted in all patients treated with a two-field proton beam at any follow-up time point except for one. For all patients, the mean percentage breast retraction assessment (pBRA) value increased significantly during the follow-up period (p = 0.02); however, it did not increase in patients treated with two-field PB-APBI (p = 0.3). Conclusions: PB-APBI consisting of 30 CGE in six CGE fractions once daily for five consecutive days can be delivered with excellent disease control and tolerable skin toxicity to properly selected patients with early-stage breast cancer. Multiple-field PB-APBI may achieve a high rate of good-to-excellent cosmetic outcomes. Additional clinical trials with larger patient groups are needed

  4. Combined effect of dopant and electron beam-irradiation on phase transition in lithium potassium sulphate

    Science.gov (United States)

    Kassem, M. E.; Gaafar, M.; Abdel Gawad, M. M. H.; El-Muraikhi, M.; Ragab, I. M.

    2004-02-01

    Thermodynamic studies of polycrystalline ruthenium (Ru) doped LiKSO 4 have been made for different concentrations of Ru in the range 0%, 0.1%, 0.2%, 0.5%, 1%, 2%, 3% by weight. The thermal behaviour has been investigated using a differential scanning calorimeter in the vicinity of high temperature phases. From this, the effect of electron beam-irradiation on the thermal properties of these polycrystalline samples has been studied. The results showed a change in the transition temperature Tc, as well as the value of specific heat CPmax at the transition temperature due to the change in Ru content and irradiation energies. The change of enthalpy and entropy of the polycrystalline have been estimated numerically.

  5. Combined effect of dopant and electron beam-irradiation on phase transition in lithium potassium sulphate

    International Nuclear Information System (INIS)

    Kassem, M.E.; Gaafar, M.; Abdel Gawad, M.M.H.; El-Muraikhi, M.; Ragab, I.M.

    2004-01-01

    Thermodynamic studies of polycrystalline ruthenium (Ru) doped LiKSO 4 have been made for different concentrations of Ru in the range 0%, 0.1%, 0.2%, 0.5%, 1%, 2%, 3% by weight. The thermal behaviour has been investigated using a differential scanning calorimeter in the vicinity of high temperature phases. From this, the effect of electron beam-irradiation on the thermal properties of these polycrystalline samples has been studied. The results showed a change in the transition temperature T c , as well as the value of specific heat C P max at the transition temperature due to the change in Ru content and irradiation energies. The change of enthalpy and entropy of the polycrystalline have been estimated numerically

  6. 3D algebraic iterative reconstruction for cone-beam x-ray differential phase-contrast computed tomography.

    Science.gov (United States)

    Fu, Jian; Hu, Xinhua; Velroyen, Astrid; Bech, Martin; Jiang, Ming; Pfeiffer, Franz

    2015-01-01

    Due to the potential of compact imaging systems with magnified spatial resolution and contrast, cone-beam x-ray differential phase-contrast computed tomography (DPC-CT) has attracted significant interest. The current proposed FDK reconstruction algorithm with the Hilbert imaginary filter will induce severe cone-beam artifacts when the cone-beam angle becomes large. In this paper, we propose an algebraic iterative reconstruction (AIR) method for cone-beam DPC-CT and report its experiment results. This approach considers the reconstruction process as the optimization of a discrete representation of the object function to satisfy a system of equations that describes the cone-beam DPC-CT imaging modality. Unlike the conventional iterative algorithms for absorption-based CT, it involves the derivative operation to the forward projections of the reconstructed intermediate image to take into account the differential nature of the DPC projections. This method is based on the algebraic reconstruction technique, reconstructs the image ray by ray, and is expected to provide better derivative estimates in iterations. This work comprises a numerical study of the algorithm and its experimental verification using a dataset measured with a three-grating interferometer and a mini-focus x-ray tube source. It is shown that the proposed method can reduce the cone-beam artifacts and performs better than FDK under large cone-beam angles. This algorithm is of interest for future cone-beam DPC-CT applications.

  7. Void fraction measurements in two-phase flow by transmission and scattering of a neutrons beam

    International Nuclear Information System (INIS)

    Souza, M.C.L.

    1984-01-01

    Calibration curves have been obtained which supply average values of void fraction (α) of water-steam two-phase mixtures for bubble, slug, annular and invert annular flow states. The measurements were carried out in simulated models of lucite-air for the steady-state, using the techniques of transmission and diffusion of a thermal neutrons beam. The calibration curves obtained were used for measurements of void fraction in a circuit containing two-phase water-air mixtures, in upward concurrent flow, for slug flow (P sub(max) = 1,06 bar) and annular flow (P sub(max) = 1,33 bar), using the same techniques. In both of the systems, a test section made up of an aluminium (99,9%) tube was used with internal diameter of 25,25 mm and 2,0 mm wall thichness. The beam of neutrons was obtained from a 5 Ci isotopic Am-Be source, thermalised in a cylindrical moderator of paraffin of 500 mm diameter (with H/D=1) which was covered by 2 mm thick cadmium sheets and having in its centre a parallepeliped made from high density polyethilene with the dimensions 240 x 240 x 144 mm. The neutrons escape through a rectangular collimator of 53,0 x 25,25 mm, with a length of 273 mm cut out of a single block of borated paraffin (32% of H 3 BO 3 ). The experimental results are in good agreement with theorical models in published literature. (Author) [pt

  8. Multi-beam linear accelerator EVT

    Energy Technology Data Exchange (ETDEWEB)

    Teryaev, Vladimir E., E-mail: vladimir_teryaev@mail.ru [Omega-P, Inc., New Haven, CT 06510 (United States); Kazakov, Sergey Yu. [Fermilab, Batavia, IL 60510 (United States); Hirshfield, Jay L. [Omega-P, Inc., New Haven, CT 06510 (United States); Yale University, New Haven, CT 06511 (United States)

    2016-09-01

    A novel electron multi-beam accelerator is presented. The accelerator, short-named EVT (Electron Voltage Transformer) belongs to the class of two-beam accelerators. It combines an RF generator and essentially an accelerator within the same vacuum envelope. Drive beam-lets and an accelerated beam are modulated in RF modulators and then bunches pass into an accelerating structure, comprising uncoupled with each other and inductive tuned cavities, where the energy transfer from the drive beams to the accelerated beam occurs. A phasing of bunches is solved by choice correspond distances between gaps of the adjacent cavities. Preliminary results of numerical simulations and the initial specification of EVT operating in S-band, with a 60 kV gun and generating a 2.7 A, 1.1 MV beam at its output is presented. A relatively high efficiency of 67% and high design average power suggest that EVT can find its use in industrial applications.

  9. Calibration artefacts in radio interferometry - III. Phase-only calibration and primary beam correction

    Science.gov (United States)

    Grobler, T. L.; Stewart, A. J.; Wijnholds, S. J.; Kenyon, J. S.; Smirnov, O. M.

    2016-09-01

    This is the third installment in a series of papers in which we investigate calibration artefacts. Calibration artefacts (also known as ghosts or spurious sources) are created when we calibrate with an incomplete model. In the first two papers of this series, we developed a mathematical framework which enabled us to study the ghosting mechanism itself. An interesting concomitant of the second paper was that ghosts appear in symmetrical pairs. This could possibly account for spurious symmetrization. Spurious symmetrization refers to the appearance of a spurious source (the antighost) symmetrically opposite an unmodelled source around a modelled source. The analysis in the first two papers indicates that the antighost is usually very faint, in particular, when a large number of antennas are used. This suggests that spurious symmetrization will mainly occur at an almost undetectable flux level. In this paper, we show that phase-only calibration produces an antighost that is N-times (where N denotes the number of antennas in the array) as bright as the one produced by phase and amplitude calibration and that this already bright ghost can be further amplified by the primary beam correction.

  10. Effect of Beam Scanning on Target Polarization Scattering Matrix Observed by Fully Polarimetric Phased-array Radar

    Directory of Open Access Journals (Sweden)

    Li Mianquan

    2016-04-01

    Full Text Available The polarization feature of a fully Polarimetric Phased-Array Radar (PPAR antenna varies according to the beam-scanning angle, thereby introducing two problems on the target Polarization Scattering Matrix (PSM measurement. First, the antenna polarization basis is defined within the vertical cross-section of an electromagnetic wave propagation direction, and the polarization basis of each beam direction angle is not identical, resulting in the PSM of a fixed-posture target observed by PPAR being not identical for different beam-scanning angles. Second, the cross polarization of the PPAR antenna increases with increasing beamscanning angle, resulting in a crosstalk among the elements of PSM observed by PPAR. This study focuses on the analysis of the abovementioned two aspects of the effect of beam scanning on target PSM observed by PPAR. The results will establish a more accurate observation of the equation for the precision PSM measurement of PPAR.

  11. A local region of interest image reconstruction via filtered backprojection for fan-beam differential phase-contrast computed tomography

    International Nuclear Information System (INIS)

    Qi Zhihua; Chen Guanghong

    2007-01-01

    Recently, x-ray differential phase contrast computed tomography (DPC-CT) has been experimentally implemented using a conventional source combined with several gratings. Images were reconstructed using a parallel-beam reconstruction formula. However, parallel-beam reconstruction formulae are not directly applicable for a large image object where the parallel-beam approximation fails. In this note, we present a new image reconstruction formula for fan-beam DPC-CT. There are two major features in this algorithm: (1) it enables the reconstruction of a local region of interest (ROI) using data acquired from an angular interval shorter than 180 0 + fan angle and (2) it still preserves the filtered backprojection structure. Numerical simulations have been conducted to validate the image reconstruction algorithm. (note)

  12. Impedance-based analysis and study of phase sensitivity in slow-wave two-beam accelerators

    International Nuclear Information System (INIS)

    Wurtele, J.S.; Whittum, D.H.; Sessler, A.M.

    1992-06-01

    This paper presents a new formalism which makes the analysis and understanding of both the relativistic klystron (RK) and the standing-wave free-electron laser (SWFEL) two-beam accelerator (TBA) available to a wide audience of accelerator physicists. A ''coupling impedance'' for both the RK and SWFEWL is introduced, which can include realistic cavity features, such as beam and vacuum ports, in a simple manner. The RK and SWFEL macroparticle equations, which govern the energy and phase evolution of successive bunches in the beam, are of identical form, differing only by multiplicative factors. Expressions are derived for the phase and amplitude sensitivities of the TBA schemes to errors (shot-to-shot jitter) in current and energy. The analysis allows, for the first time, relative comparisons of the RK and the SWFEL TBAs

  13. Matched-filtering generalized phase contrast using LCoS pico-projectors for beam-forming.

    Science.gov (United States)

    Bañas, Andrew; Palima, Darwin; Glückstad, Jesper

    2012-04-23

    We report on a new beam-forming system for generating high intensity programmable optical spikes using so-called matched-filtering Generalized Phase Contrast (mGPC) applying two consumer handheld pico-projectors. Such a system presents a low-cost alternative for optical trapping and manipulation, optical lattices and other beam-shaping applications usually implemented with high-end spatial light modulators. Portable pico-projectors based on liquid crystal on silicon (LCoS) devices are used as binary phase-only spatial light modulators by carefully setting the appropriate polarization of the laser illumination. The devices are subsequently placed into the object and Fourier plane of a standard 4f-setup according to the mGPC spatial filtering configuration. Having a reconfigurable spatial phase filter, instead of a fixed and fabricated one, allows the beam shaper to adapt to different input phase patterns suited for different requirements. Despite imperfections in these consumer pico-projectors, the mGPC approach tolerates phase aberrations that would have otherwise been hard to overcome by standard phase projection. © 2012 Optical Society of America

  14. Matched-filtering generalized phase contrast using LCoS pico-projectors for beam-forming

    DEFF Research Database (Denmark)

    Bañas, Andrew Rafael; Palima, Darwin; Glückstad, Jesper

    2012-01-01

    , optical lattices and other beam-shaping applications usually implemented with high-end spatial light modulators. Portable pico-projectors based on liquid crystal on silicon (LCoS) devices are used as binary phase-only spatial light modulators by carefully setting the appropriate polarization of the laser...

  15. Cumulative-Phase-Alteration of Galactic-Light Passing Through the Cosmic-Microwave-Background: A New Mechanism for Some Observed Spectral-Shifts

    Directory of Open Access Journals (Sweden)

    Tank H. K.

    2012-07-01

    Full Text Available Currently, whole of the measured “cosmological-red-shift ” is interpreted as due to the “metric-expansion-of-space”; so for the required “closer -density” of the universe, we need twenty times more mass-energy than the visible baryonic-matter contained in the universe. This paper proposes a new mechanism, which can account for good per- centage of the red-shift in the extra-galactic-light, greatly reducing the requirement of dark matter-energy. Also, this mechanism can cause a new kin d of blue-shift reported here, and their observational evidences. These spectral-s hifts are proposed to result due to cumulative phase-alteration of extra-galactic-light b ecause of vector-addition of: (i electric-field of extra-galactic-light and (ii that of the cosmic-microwave-background (CMB. Since the center-frequency of CMB is much lower than extra-galactic-light, the cumulative-phase-alteration results in red -shift, observed as an additional contribu- tor to the measured “cosmological red-shift”; and since the center-frequency of CMB is higher than the radio-frequency-signals used to measure velocity of space-probes like: Pioneer-10, Pioneer-11, Galileo and Ulysses, the cum ulative-phase-alteration re- sulted in blue-shift, leading to the interpretation of deceleration of these space-probes. While the galactic-light experiences the red-shift, and th e ranging-signals of the space- probes experience blue -shift, they are comparable in magnitude, providing a supportive- evidence for the new mechanism proposed here. More confirmative-experiments for this new mechanism are also proposed.

  16. Fiber-based coherent polarization beam combining with cascaded phase-locking and polarization-transforming controls

    Science.gov (United States)

    Yang, Yan; Geng, Chao; Li, Feng; Huang, Guan; Li, Xinyang

    2018-05-01

    In this paper, the fiber-based coherent polarization beam combining (CPBC) with cascaded phase-locking (PL) and polarization-transforming (PT) controls was proposed to combine imbalanced input beams where the number of the input beams is not binary, in which the PL control was performed using the piezoelectric-ring fiber-optic phase compensator, and the PT control was realized by the dynamic polarization controller, simultaneously. The principle of the proposed CPBC was introduced. The performance of the proposed CPBC was analyzed in comparison with the CPBC based on PL control and the CPBC based on PT control. The basic experiment of CPBC of three laser beams was carried out to validate the feasibility of the proposed CPBC, where cascaded controls of PL and PT were implemented based on stochastic parallel gradient descent algorithm. Simulation and experimental results show that the proposed CPBC incorporates the advantages of the two previous CPBC schemes and performs well in the closed loop. Moreover, the expansibility and the application of the proposed CPBC were validated by scaling the CPBC to combine seven laser beams. We believe that the proposed fiber-based CPBC with cascaded PL and PT controls has great potential in free space optical communications employing the multi-aperture receiver with asymmetric structure.

  17. High-efficiency resonant rf spin rotator with broad phase space acceptance for pulsed polarized cold neutron beams

    Directory of Open Access Journals (Sweden)

    P.-N. Seo

    2008-08-01

    Full Text Available High precision fundamental neutron physics experiments have been proposed for the intense pulsed spallation neutron beams at JSNS, LANSCE, and SNS to test the standard model and search for new physics. Certain systematic effects in some of these experiments have to be controlled at the few ppb level. The NPDGamma experiment, a search for the small parity-violating γ-ray asymmetry A_{γ} in polarized cold neutron capture on parahydrogen, is one example. For the NPDGamma experiment we developed a radio-frequency resonant spin rotator to reverse the neutron polarization in a 9.5  cm×9.5  cm pulsed cold neutron beam with high efficiency over a broad cold neutron energy range. The effect of the spin reversal by the rotator on the neutron beam phase space is compared qualitatively to rf neutron spin flippers based on adiabatic fast passage. We discuss the design of the spin rotator and describe two types of transmission-based neutron spin-flip efficiency measurements where the neutron beam was both polarized and analyzed by optically polarized ^{3}He neutron spin filters. The efficiency of the spin rotator was measured at LANSCE to be 98.8±0.5% for neutron energies from 3 to 20 meV over the full phase space of the beam. Systematic effects that the rf spin rotator introduces to the NPDGamma experiment are considered.

  18. High Charge PHIN Photo Injector at CERN with Fast Phase switching within the Bunch Train for Beam Combination

    CERN Document Server

    Csatari Divall, M; Bolzon, B; Bravin, E; Chevallay, E; Dabrowski, A; Doebert, S; Drozdy, A; Fedosseev, V; Hessler, C; Lefevre, T; Livesley, S; Losito, R; Olvegaard, M; Petrarca, M; Rabiller, A N; Egger, D; Mete, O

    2011-01-01

    The high charge PHIN photo-injector was developed within the framework of the European CARE program to provide an alternative to the drive beam thermionic gun in the CTF3 (CLIC Test Facility) at CERN. In PHIN 1908 electron bunches are delivered with bunch spacing of 1.5 GHz and 2.33 nC charge per bunch. Furthermore the drive beam generated by CTF3 requires several fast 180 deg phase-shifts with respect to the 1.5 GHz bunch repetition frequency in order to allow the beam combination scheme developed at CTF3. A total of 8 subtrains, each 140 ns long and shifted in phase with respect to each other, have to be produced with very high phase and amplitude stability. A novel fiber modulator based phase-switching technique developed on the laser system provides this phase-shift between two consecutive pulses much faster and cleaner than the base line scheme, where a thermionic electron gun and sub-harmonic bunching are used. The paper describes the fiber-based switching system and the measurements verifying the schem...

  19. The research of the beam phase and energy test system for DTL in the proton accelerator of CSNS

    International Nuclear Information System (INIS)

    Zhao Lei; Liu Shubin; An Qi

    2009-01-01

    China Spallation Neutron Source is now in the process of research and design,in which the proton accelerator is an important part. This beam phase and energy test system imports the signal from the Drift Tube Linac and computes its phase and energy, which is feedback to tune the beam. The signals to be processed here are modulated impulses of high frequency (repetition rate is 352.2 MHz, while the leading edge is only hundreds of ps), and the dynamic range of the amplitude is from 20 mv to 900 mv (peak to peak); therefore, special techniques are required to obtain its phase information. Moreover, to confirm the basic theory of corresponding techniques and evaluate their effects, some simulations are implemented in the platform of Matlab. (authors)

  20. Modeling of Focused Acoustic Field of a Concave Multi-annular Phased Array Using Spheroidal Beam Equation

    Science.gov (United States)

    Yu, Li-Li; Shou, Wen-De; Hui, Chun

    2012-02-01

    A theoretical model of focused acoustic field for a multi-annular phased array on concave spherical surface is proposed. In this model, the source boundary conditions of the spheroidal beam equation (SBE) for multi-annular phased elements are studied. Acoustic field calculated by the dynamic focusing model of SBE is compared with numerical results of the O'Neil and Khokhlov—Zabolotskaya—Kuznetsov (KZK) model, respectively. Axial dynamic focusing and the harmonic effects are presented. The results demonstrate that the dynamic focusing model of SBE is good valid for a concave multi-annular phased array with a large aperture angle in the linear or nonlinear field.

  1. Symmetry control using beam phasing in ∼0.2 NIF scale high temperature Hohlraum experiment on OMEGA

    International Nuclear Information System (INIS)

    Delamater, Norman D.; Wilson, Goug C.; Kyrala, George A.; Seifter, Achim; Hoffman, N.M.; Dodd, E.; Glebov, V.

    2009-01-01

    Results are shown from recent experiments at the Omega laser facility, using 40 Omega beams driving the hohlraum with 3 cones from each side and up to 19.5 kJ of laser energy. Beam phasing is achieved by decreasing the energy separately in each of the three cones, by 3 kJ, for a total drive energy of 16.5kJ. This results in a more asymmetric drive, which will vary the shape of the imploded symmetry capsule core from round to oblate or prolate in a systematic and controlled manner. These results would be the first demonstration of beam phasing for implosions in such 'high temperature' (275 eV) hohlraums at Omega. Dante measurements confirmed the predicted peak drive temperatures of 275 eV. Implosion core time dependent x-ray images were obtained from framing camera data which show the expected change in symmetry due to beam phasing and which also agree well with post processed hydro code calculations. Time resolved hard x-ray data has been obtained and it was found that the hard x-rays are correlated mainly with the low angle 21 o degree cone.

  2. Accelerated partial breast irradiation with external beam radiotherapy. First results of the German phase 2 trial

    Energy Technology Data Exchange (ETDEWEB)

    Ott, Oliver J.; Strnad, Vratislav; Stillkrieg, Wilhelm; Fietkau, Rainer [University Hospital Erlangen, Department of Radiation Oncology, Erlangen (Germany); Uter, Wolfgang [University Erlangen-Nuremberg, Dept. of Medical Informatics, Biometry and Epidemiology, Erlangen (Germany); Beckmann, Matthias W. [University Hospital Erlangen, Dept. of Gynecology, Erlangen (Germany)

    2017-01-15

    To evaluate the feasibility and efficacy of external beam three-dimensional (3D) conformal accelerated partial breast irradiation (APBI) for selected patients with early breast cancer. Between 2011 and 2016, 72 patients were recruited for this prospective phase 2 trial. Patients were eligible for APBI if they had histologically confirmed breast cancer or pure ductal carcinoma in situ (DCIS), a tumor diameter ≤3 cm, clear resection margins ≥2 mm, no axillary lymph node involvement, no distant metastases, tumor bed clips, and were aged ≥50 years. Patients were excluded if mammography showed a multicentric invasive growth pattern, or if they had residual diffuse microcalcifications postoperatively, an extensive intraductal component, or vessel invasion. Patients received 3D conformal external beam APBI with a total dose of 38 Gy in 10 fractions in 1-2 weeks. The trial had been registered at the German Clinical Trials Register, DRKS-ID: DRKS00004417. Median follow-up was 25.5 months (range 1-61 months). Local control was maintained in 71 of 72 patients. The 3-year local recurrence rate was 2.1% (95% confidence interval, CI: 0-6.1%). Early toxicity (grade 1 radiodermatitis) was seen in 34.7% (25/72). Late side effects ≥ grade 3 did not occur. Cosmetic results were rated as excellent/good in 96.7% (59/61). APBI with external beam radiotherapy techniques is feasible with low toxicity and, according to the results of the present and other studies, on the way to becoming a standard treatment option for a selected subgroup of patients. (orig.) [German] Untersuchung der Vertraeglichkeit und Sicherheit der externen, 3-D-konformalen akzelerierten Teilbrustbestrahlung (APBI) fuer ausgewaehlte Patientinnen mit einem fruehen Mammakarzinom. Von 2011 bis 2016 wurden 72 Patientinnen in diese prospektive Phase-2-Studie eingebracht. Einschlusskriterien waren ein histologisch gesichertes Mammakarzinom oder DCIS, ein Tumordurchmesser ≤ 3 cm, tumorfreie Resektionsraender ≥ 2

  3. Test Beam Performance Measurements for the Phase I Upgrade of the CMS Pixel Detector

    CERN Document Server

    Dragicevic, M.; Hrubec, J.; Steininger, H.; Gädda, A.; Härkönen, J.; Lampén, T.; Luukka, P.; Peltola, T.; Tuominen, E.; Tuovinen, E.; Winkler, A.; Eerola, P.; Tuuva, T.; Baulieu, G.; Boudoul, G.; Caponetto, L.; Combaret, C.; Contardo, D.; Dupasquier, T.; Gallbit, G.; Lumb, N.; Mirabito, L.; Perries, S.; Donckt, M.Vander; Viret, S.; Bonnin, C.; Charles, L.; Gross, L.; Hosselet, J.; Tromson, D.; Feld, L.; Karpinski, W.; Klein, K.; Lipinski, M.; Pierschel, G.; Preuten, M.; Rauch, M.; Wlochal, M.; Aldaya, M.; Asawatangtrakuldee, C.; Beernaert, K.; Bertsche, D.; Contreras-Campana, C.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Gallo, E.; Garcia, J.Garay; Hansen, K.; Haranko, M.; Harb, A.; Hauk, J.; Keaveney, J.; Kalogeropoulos, A.; Kleinwort, C.; Lohmann, W.; Mankel, R.; Maser, H.; Mittag, G.; Muhl, C.; Mussgiller, A.; Pitzl, D.; Reichelt, O.; Savitskyi, M.; Schütze, P.; Sola, V.; Spannagel, S.; Walsh, R.; Zuber, A.; Biskop, H.; Buhmann, P.; Centis-Vignali, M.; Garutti, E.; Haller, J.; Hoffmann, M.; Klanner, R.; Lapsien, T.; Matysek, M.; Perieanu, A.; Scharf, Ch.; Schleper, P.; Schmidt, A.; Schwandt, J.; Sonneveld, J.; Steinbrück, G.; Vormwald, B.; Wellhausen, J.; Abbas, M.; Amstutz, C.; Barvich, T.; Barth, Ch.; Boegelspacher, F.; Boer, W.De; Butz, E.; Casele, M.; Colombo, F.; Dierlamm, A.; Freund, B.; Hartmann, F.; Heindl, S.; Husemann, U.; Kornmeyer, A.; Kudella, S.; Muller, Th.; Simonis, H.J.; Steck, P.; Weber, M.; Weiler, Th.; Kiss, T.; Siklér, F.; Tölyhi, T.; Veszprémi, V.; Cariola, P.; Creanza, D.; Palma, M.De; Robertis, G.De; Fiore, L.; Franco, M.; Loddo, F.; Sala, G.; Silvestris, L.; Maggi, G.; My, S.; Selvaggi, G.; Albergo, S.; Cappello, G.; Costa, S.; Mattia, A.Di; Giordano, F.; Potenza, R.; Saizu, M.A.; Tricomi, A.; Tuve, C.; Focardi, E.; Dinardo, M.E.; Fiorendi, S.; Gennai, S.; Malvezzi, S.; Manzoni, R.A.; Menasce, D.; Moroni, L.; Pedrini, D.; Azzi, P.; Bacchetta, N.; Bisello, D.; Dall'Osso, M.; Pozzobon, N.; Tosi, M.; Solestizi, L.Alunni; Biasini, M.; Bilei, G.M.; Cecchi, C.; Checcucci, B.; Ciangottini, D.; Fanò, L.; Gentsos, C.; Ionica, M.; Leonardi, R.; Manoni, E.; Mantovani, G.; Marconi, S.; Mariani, V.; Menichelli, M.; Modak, A.; Morozzi, A.; Moscatelli, F.; Passeri, D.; Placidi, P.; Postolache, V.; Rossi, A.; Saha, A.; Santocchia, A.; Storchi, L.; Spiga, D.; Androsov, K.; Azzurri, P.; Bagliesi, G.; Basti, A.; Boccali, T.; Borrello, L.; Bosi, F.; Castaldi, R.; Ceccanti, M.; Ciocci, M.A.; Dell'Orso, R.; Donato, S.; Fedi, G.; Giassi, A.; Grippo, M.T.; Ligabue, F.; Magazzu, G.; Mammini, P.; Mariani, F.; Mazzoni, E.; Messineo, A.; Moggi, A.; Morsani, F.; Palla, F.; Palmonari, F.; Profeti, A.; Raffaelli, F.; Ragonesi, A.; Rizzi, A.; Soldani, A.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P.G.; Abbaneo, D.; Ahmed, I.; Albert, E.; Auzinger, G.; Berruti, G.; Bonnaud, J.; Daguin, J.; D'Auria, A.; Detraz, S.; Dondelewski, O.; Engegaard, B.; Faccio, F.; Frank, N.; Gill, K.; Honma, A.; Kornmayer, A.; Labaza, A.; Manolescu, F.; McGill, I.; Mersi, S.; Michelis, S.; Onnela, A.; Ostrega, M.; Pavis, S.; Peisert, A.; Pernot, J.F.; Petagna, P.; Postema, H.; Rapacz, K.; Sigaud, C.; Tropea, P.; Troska, J.; Tsirou, A.; Vasey, F.; Verlaat, B.; Vichoudis, P.; Zwalinski, L.; Bachmair, F.; Becker, R.; di Calafiori, D.; Casal, B.; Berger, P.; Djambazov, L.; Donega, M.; Grab, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Lustermann, W.; Mangano, B.; Marionneau, M.; Arbol, P.Martinez Ruiz del; Masciovecchio, M.; Meinhard, M.; Perozzi, L.; Roeser, U.; Starodumov, A.; Tavolaro, V.; Wallny, R.; Zhu, D.; Amsler, C.; Bösiger, K.; Caminada, L.; Canelli, F.; Chiochia, V.; de Cosa, A.; Galloni, C.; Hreus, T.; Kilminster, B.; Lange, C.; Maier, R.; Ngadiuba, J.; Pinna, D.; Robmann, P.; Taroni, S.; Yang, Y.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Kaestli, H.C.; Kotlinski, D.; Langenegger, U.; Meier, B.; Rohe, T.; Streuli, S.; Chen, P.H.; Dietz, C.; Fiori, F.; Grundler, U.; Hou, W.S.; Lu, R.S.; Moya, M.; Tsai, J.F.; Tzeng, Y.M.; Cussans, D.; Goldstein, J.; Grimes, M.; Newbold, D.; Hobson, P.; Reid, I.D.; Auzinger, G.; Bainbridge, R.; Dauncey, P.; Hall, G.; James, T.; Magnan, A.M.; Pesaresi, M.; Raymond, D.M.; Uchida, K.; Durkin, T.; Harder, K.; Shepherd-Themistocleous, C.; Chertok, M.; Conway, J.; Conway, R.; Flores, C.; Lander, R.; Pellett, D.; Ricci-Tam, F.; Squires, M.; Thomson, J.; Yohay, R.; Burt, K.; Ellison, J.; Hanson, G.; Olmedo, M.; Si, W.; Yates, B.R.; Dominguez, A.; Bartek, R.; Bentele, B.; Cumalat, J.P.; Ford, W.T.; Jensen, F.; Johnson, A.; Krohn, M.; Leontsinis, S.; Mulholland, T.; Stenson, K.; Wagner, S.R.; Apresyan, A.; Bolla, G.; Burkett, K.; Butler, J.N.; Canepa, A.; Cheung, H.W.K.; Christian, D.; Cooper, W.E.; Deptuch, G.; Derylo, G.; Gingu, C.; Grünendahl, S.; Hasegawa, S.; Hoff, J.; Howell, J.; Hrycyk, M.; Jindariani, S.; Johnson, M.; Kahlid, F.; Kwan, S.; Lei, C.M.; Lipton, R.; Sá, R.Lopes De; Liu, T.; Los, S.; Matulik, M.; Merkel, P.; Nahn, S.; Prosser, A.; Rivera, R.; Schneider, B.; Sellberg, G.; Shenai, A.; Siehl, K.; Spiegel, L.; Tran, N.; Uplegger, L.; Voirin, E.; Berry, D.R.; Chen, X.; Ennesser, L.; Evdokimov, A.; Gerber, C.E.; Makauda, S.; Mills, C.; Gonzalez, I.D.Sandoval; Alimena, J.; Antonelli, L.J.; Francis, B.; Hart, A.; Hill, C.S.; Parashar, N.; Stupak, J.; Bortoletto, D.; Bubna, M.; Hinton, N.; Jones, M.; Miller, D.H.; Shi, X.; Baringer, P.; Bean, A.; Khalil, S.; Kropivnitskaya, A.; Majumder, D.; Schmitz, E.; Wilson, G.; Ivanov, A.; Mendis, R.; Mitchell, T.; Skhirtladze, N.; Taylor, R.; Anderson, I.; Fehling, D.; Gritsan, A.; Maksimovic, P.; Martin, C.; Nash, K.; Osherson, M.; Swartz, M.; Xiao, M.; Acosta, J.G.; Cremaldi, L.M.; Oliveros, S.; Perera, L.; Summers, D.; Bloom, K.; Claes, D.R.; Fangmeier, C.; Suarez, R.Gonzalez; Monroy, J.; Siado, J.; Bartz, E.; Gershtein, Y.; Halkiadakis, E.; Kyriacou, S.; Lath, A.; Nash, K.; Osherson, M.; Schnetzer, S.; Stone, R.; Walker, M.; Malik, S.; Norberg, S.; Vargas, J.E.Ramirez; Alyari, M.; Dolen, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Kharchilava, A.; Nguyen, D.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; McDermott, K.; Mirman, N.; Rinkevicius, A.; Ryd, A.; Salvati, E.; Skinnari, L.; Soffi, L.; Tao, Z.; Thom, J.; Tucker, J.; Zientek, M.; Akgün, B.; Ecklund, K.M.; Kilpatrick, M.; Nussbaum, T.; Zabel, J.; D'Angelo, P.; Johns, W.; Rose, K.

    2017-05-30

    A new pixel detector for the CMS experiment is being built, owing to the instantaneous luminosities anticipated for the Phase I Upgrade of the LHC. The new CMS pixel detector provides four-hit tracking while featuring a reduced material budget as well as new cooling and powering schemes. A new front-end readout chip mitigates buffering and bandwidth limitations, and comprises a low-threshold comparator. These upgrades allow the new pixel detector to sustain and improve the efficiency of the current pixel tracker at the increased requirements imposed by high luminosities and pile-up. In this paper, comprehensive test beam studies are presented which have been conducted to verify the design and to quantify the performance of the new detector assemblies in terms of tracking efficiency and spatial resolution. Under optimal conditions, the tracking efficiency has been determined to be ($99.95 \\pm 0.05$) \\%, while the intrinsic spatial resolution has been measured to be ($4.80 \\pm 0.25$) $\\mu$m and ($7.99 \\pm 0.21$...

  4. Volume phase holographic grating used for beams combination of RGB primary colors

    Science.gov (United States)

    Liu, Hui; Zhang, Xizhao; Tang, Minxue

    2013-12-01

    Volume phase holographic grating (VPHG) has the characteristics of high diffraction efficiency, high signal to noise ratio, high wavelength and angular selectivity, low scattering , low absorption and low cost. It has been widely used in high resolution spectrometer, wavelength division multiplexing and pulse compression technique. In this paper, a novel kind of RGB primary colors beams combiner which is consisted of a transmission VPHG and a reflection VPHG as core components is proposed. The design idea of the element is described in detail. Based on the principle of VPHG, the rigorous coupled wave analysis (RCWA) and Kogelnik's coupled wave theory, diffraction properties of the transmission and reflection VPHG are studied theoretically. As an example, three primary colors at wavelengths of 632.8nm, 532nm and 476.5nm are taken into account. Dichromated gelatin (DCG) is used as the holographic recording material. The grating parameters are determined by the Bragg conditions. The TE and TM wave diffraction efficiency, the wavelength selectivity and the angular selectivity of the transmission and reflection VPHG are calculated and optimized by setting the amplitude of the index modulation (Δn) and the thickness of the gelatin layer (d) by applying Kogelnik's coupled wave theory and G-solver software, respectively. The theoretical calculating results give guidance for further manufacture of the element.

  5. Decomposition of gas-phase diphenylether at 473 K by electron beam generated plasma

    CERN Document Server

    Kim, H H; Kojima, T

    2003-01-01

    Decomposition of gas-phase diphenylether (DPE) in the order of several parts per million by volume (ppmv) was studied as a model compound of dioxin using a flow-type electron-beam reactor at an elevated temperature of 473 K. The ground state oxygen ( sup 3 P) atoms played an important role in the decomposition of DPE resulting in the formation of 1,4-hydroquinone (HQ) as a major ring retaining product. The high yield of hydroquinone indicated that the breakage of ether bond (C-O) is important in the initial step of DPE decomposition. Ring cleavage products were CO and CO sub 2 , and NO sub 2 was also produced from background N sub 2 -O sub 2. The sum of the yields of HQ, CO sub 2 and CO accounts for over 90% of the removed DPE. Hydroxyl radicals (OH) were less important in the dilute DPE decomposition at a high water content, and were mostly consumed by recombination reactions to form hydrogen peroxide. The smaller the initial DPE concentrations, the higher the decomposition efficiency and the lower the yield...

  6. Matched-filtering generalized phase contrast using LCoS pico-projectors for beam-forming

    OpenAIRE

    Bañas, Andrew Rafael; Palima, Darwin; Glückstad, Jesper

    2012-01-01

    We report on a new beam-forming system for generating high intensity programmable optical spikes using so-called matched-filtering Generalized Phase Contrast (mGPC) applying two consumer handheld pico-projectors. Such a system presents a low-cost alternative for optical trapping and manipulation, optical lattices and other beam-shaping applications usually implemented with high-end spatial light modulators. Portable pico-projectors based on liquid crystal on silicon (LCoS) devices are used as...

  7. The genome sequence of the outbreeding globe artichoke constructed de novo incorporating a phase-aware low-pass sequencing strategy of F1 progeny

    Science.gov (United States)

    Scaglione, Davide; Reyes-Chin-Wo, Sebastian; Acquadro, Alberto; Froenicke, Lutz; Portis, Ezio; Beitel, Christopher; Tirone, Matteo; Mauro, Rosario; Lo Monaco, Antonino; Mauromicale, Giovanni; Faccioli, Primetta; Cattivelli, Luigi; Rieseberg, Loren; Michelmore, Richard; Lanteri, Sergio

    2016-01-01

    Globe artichoke (Cynara cardunculus var. scolymus) is an out-crossing, perennial, multi-use crop species that is grown worldwide and belongs to the Compositae, one of the most successful Angiosperm families. We describe the first genome sequence of globe artichoke. The assembly, comprising of 13,588 scaffolds covering 725 of the 1,084 Mb genome, was generated using ~133-fold Illumina sequencing data and encodes 26,889 predicted genes. Re-sequencing (30×) of globe artichoke and cultivated cardoon (C. cardunculus var. altilis) parental genotypes and low-coverage (0.5 to 1×) genotyping-by-sequencing of 163 F1 individuals resulted in 73% of the assembled genome being anchored in 2,178 genetic bins ordered along 17 chromosomal pseudomolecules. This was achieved using a novel pipeline, SOILoCo (Scaffold Ordering by Imputation with Low Coverage), to detect heterozygous regions and assign parental haplotypes with low sequencing read depth and of unknown phase. SOILoCo provides a powerful tool for de novo genome analysis of outcrossing species. Our data will enable genome-scale analyses of evolutionary processes among crops, weeds, and wild species within and beyond the Compositae, and will facilitate the identification of economically important genes from related species. PMID:26786968

  8. Delayed-Phase Cone-Beam CT Improves Detectability of Intrahepatic Cholangiocarcinoma During Conventional Transarterial Chemoembolization

    International Nuclear Information System (INIS)

    Schernthaner, Ruediger Egbert; Lin, MingDe; Duran, Rafael; Chapiro, Julius; Wang, Zhijun; Geschwind, Jean-François

    2015-01-01

    PurposeTo evaluate the detectability of intrahepatic cholangiocarcinoma (ICC) on dual-phase cone-beam CT (DPCBCT) during conventional transarterial chemoembolization (cTACE) compared to that of digital subtraction angiography (DSA) with respect to pre-procedure contrast-enhanced magnetic resonance imaging (CE-MRI) of the liver.MethodsThis retrospective study included 17 consecutive patients (10 male, mean age 64) with ICC who underwent pre-procedure CE-MRI of the liver, and DSA and DPCBCT (early-arterial phase (EAP) and delayed-arterial phase (DAP)) just before cTACE. The visibility of each ICC lesion was graded by two radiologists on a three-rank scale (complete, partial, and none) on DPCBCT and DSA images, and then compared to pre-procedure CE-MRI.ResultsOf 61 ICC lesions, only 45.9 % were depicted by DSA, whereas EAP- and DAP-CBCT yielded a significantly higher detectability rate of 73.8 % and 93.4 %, respectively (p < 0.01). Out of the 33 lesions missed on DSA, 18 (54.5 %) and 30 (90.9 %) were revealed on EAP- and DAP-CBCT images, respectively. DSA depicted only one lesion that was missed by DPCBCT due to streak artifacts caused by a prosthetic mitral valve. DAP-CBCT identified significantly more lesions than EAP-CBCT (p < 0.01). Conversely, EAP-CBCT did not detect lesions missed by DAP-CBCT. For complete lesion visibility, DAP-CBCT yielded significantly higher detectability (78.7 %) compared to EAP (31.1 %) and DSA (21.3 %) (p < 0.01).ConclusionDPCBCT, and especially the DAP-CBCT, significantly improved the detectability of ICC lesions during cTACE compared to DSA. We recommend the routine use of DAP-CBCT in patients with ICC for per-procedure detectability and treatment planning in the setting of TACE

  9. Delayed-Phase Cone-Beam CT Improves Detectability of Intrahepatic Cholangiocarcinoma During Conventional Transarterial Chemoembolization

    Energy Technology Data Exchange (ETDEWEB)

    Schernthaner, Ruediger Egbert [The Johns Hopkins Hospital, Russell H. Morgan Department of Radiology and Radiological Science, Division of Vascular and Interventional Radiology (United States); Lin, MingDe [Philips Research North America, Ultrasound and Interventions (United States); Duran, Rafael; Chapiro, Julius; Wang, Zhijun; Geschwind, Jean-François, E-mail: jfg@jhmi.edu [The Johns Hopkins Hospital, Russell H. Morgan Department of Radiology and Radiological Science, Division of Vascular and Interventional Radiology (United States)

    2015-08-15

    PurposeTo evaluate the detectability of intrahepatic cholangiocarcinoma (ICC) on dual-phase cone-beam CT (DPCBCT) during conventional transarterial chemoembolization (cTACE) compared to that of digital subtraction angiography (DSA) with respect to pre-procedure contrast-enhanced magnetic resonance imaging (CE-MRI) of the liver.MethodsThis retrospective study included 17 consecutive patients (10 male, mean age 64) with ICC who underwent pre-procedure CE-MRI of the liver, and DSA and DPCBCT (early-arterial phase (EAP) and delayed-arterial phase (DAP)) just before cTACE. The visibility of each ICC lesion was graded by two radiologists on a three-rank scale (complete, partial, and none) on DPCBCT and DSA images, and then compared to pre-procedure CE-MRI.ResultsOf 61 ICC lesions, only 45.9 % were depicted by DSA, whereas EAP- and DAP-CBCT yielded a significantly higher detectability rate of 73.8 % and 93.4 %, respectively (p < 0.01). Out of the 33 lesions missed on DSA, 18 (54.5 %) and 30 (90.9 %) were revealed on EAP- and DAP-CBCT images, respectively. DSA depicted only one lesion that was missed by DPCBCT due to streak artifacts caused by a prosthetic mitral valve. DAP-CBCT identified significantly more lesions than EAP-CBCT (p < 0.01). Conversely, EAP-CBCT did not detect lesions missed by DAP-CBCT. For complete lesion visibility, DAP-CBCT yielded significantly higher detectability (78.7 %) compared to EAP (31.1 %) and DSA (21.3 %) (p < 0.01).ConclusionDPCBCT, and especially the DAP-CBCT, significantly improved the detectability of ICC lesions during cTACE compared to DSA. We recommend the routine use of DAP-CBCT in patients with ICC for per-procedure detectability and treatment planning in the setting of TACE.

  10. Relation between the occurrence of burnout and differential-pressure fluctuation characteristics caused by the disturbance waves passing by a flow obstacle in a vertical boiling two-phase upward flow in a narrow annular channel

    International Nuclear Information System (INIS)

    Mori, Shoji; Fukano, Tohru

    2003-01-01

    If a flow obstacle such as a spacer is set in a boiling two-phase flow within an annular channel, where the inner tube is used as a heater, the temperature on the surface of the heater tube is severely affected by the existence of the spacer. In some case the spacer has a cooling effect, and in the other case it causes the dryout of the cooling liquid film on the heating surface resulting in the burnout of the tube. The burnout mechanism near the spacer, however, is not still clear. In the present paper we focus our attention on the occurrence of the burnout near a spacer, and discuss the occurrence location of dryout and burnout and the relation between the occurrence of burnout and differential-pressure fluctuation characteristics caused by the disturbance waves passing by a spacer. (author)

  11. Introduction: Mirrors of Passing

    DEFF Research Database (Denmark)

    Seebach, Sophie Hooge; Willerslev, Rane

    How is death, time, and materiality interconnected? How to approach an understanding of the world of the dead? In this introduction, we seek to understand how the experience of material decay, of the death of those around us, makes us aware of the passing of time. Through the literary lens of Neil...... Gaiman’s The Graveyard Book, we explore how the world of the dead and the world of the living can intersect; how time and materiality shifts and changes depending on who experiences it. These revelations, based on fiction, provide a mirror through which the reader can experience the varied chapters...

  12. Heavy ion inertial fusion: interface between target gain, accelerator phase space and reactor beam transport revisited

    International Nuclear Information System (INIS)

    Barletta, W.A.; Fawley, W.M.; Judd, D.L.; Mark, J.W.K.; Yu, S.S.

    1984-01-01

    Recently revised estimates of target gain have added additional optimistic inputs to the interface between targets, accelerators and fusion chamber beam transport. But it remains valid that neutralization of the beams in the fusion chamber is useful if ion charge state Z > 1 or if > 1 kA per beamlet is to be propagated. Some engineering and economic considerations favor higher currents

  13. Passing the baton

    CERN Multimedia

    2011-01-01

    It was not only in South Korea that batons were being passed last week. While the cream of the world’s athletes were competing in the World Athletics Championships, the cream of the world’s accelerator scientists were on their way to San Sebastian in Spain for the International Particle Accelerator Conference.  One of them was carrying a rather special baton for a handover of a different kind.   When Fermilab’s Vladimir Shiltsev handed the high-energy frontier baton to CERN’s Mike Lamont on Tuesday, it marked the end of an era: a time to look back on the phenomenal contribution the Tevatron has made to particle physics over its 25-year operational lifetime, and the great contribution Fermilab has made over that period to global collaboration in particle physics. There’s always a lot of emotion involved in passing the baton. In athletics, it’s the triumph of wining or the heartbreak of losing. But for this special baton, the...

  14. TRT Barrel milestones passed

    CERN Multimedia

    Ogren, H

    2004-01-01

    The barrel TRT detector passed three significant milestones this spring. The Barrel Support Structure (BSS) was completed and moved to the SR-1 building on February 24th. On March 12th the first module passed the quality assurance testing in Building 154 and was transported to the assembly site in the SR-1 building for barrel assembly. Then on April 21st the final production module that had been scanned at Hampton University was shipped to CERN. TRT Barrel Module Production The production of the full complement of barrel modules (96 plus 9 total spares) is now complete. This has been a five-year effort by Duke University, Hampton University, and Indiana University. Actual construction of the modules in the United States was completed in the first part of 2004. The production crews at each of the sites in the United States have now completed their missions. They are shown in the following pictures. Duke University: Production crew with the final completed module. Indiana University: Module producti...

  15. Beam diagnostics

    International Nuclear Information System (INIS)

    Bogaty, J.; Clifft, B.E.; Zinkann, G.P.; Pardo, R.C.

    1995-01-01

    The ECR-PII injector beam line is operated at a fixed ion velocity. The platform high voltage is chosen so that all ions have a velocity of 0.0085c at the PII entrance. If a previous tune configuration for the linac is to be used, the beam arrival time must be matched to the previous tune as well. A nondestructive beam-phase pickup detector was developed and installed at the entrance to the PII linac. This device provides continuous phase and beam current information and allows quick optimization of the beam injected into PII. Bunches traverse a short tubular electrode thereby inducing displacement currents. These currents are brought outside the vacuum interface where a lumped inductance resonates electrode capacitance at one of the bunching harmonic frequencies. This configuration yields a basic sensitivity of a few hundred millivolts signal per microampere of beam current. Beam-induced radiofrequency signals are summed against an offset frequency generated by our master oscillator. The resulting kilohertz difference frequency conveys beam intensity and bunch phase information which is sent to separate processing channels. One channel utilizes a phase locked loop which stabilizes phase readings if beam is unstable. The other channel uses a linear full wave active rectifier circuit which converts kilohertz sine wave signal amplitude to a D.C. voltage representing beam current. A prototype set of electronics is now in use with the detector and we began to use the system in operation to set the arrival beam phase. A permanent version of the electronics system for the phase detector is now under construction. Additional nondestructive beam intensity and phase monitors at the open-quotes Boosterclose quotes and open-quotes ATLASclose quotes linac sections are planned as well as on some of the high-energy beam lines. Such a monitor will be particularly useful for FMA experiments where the primary beam hits one of the electric deflector plates

  16. In situ observation of electron beam-induced phase transformation of CaCO3 to CaO via ELNES at low electron beam energies.

    Science.gov (United States)

    Golla-Schindler, Ute; Benner, Gerd; Orchowski, Alexander; Kaiser, Ute

    2014-06-01

    It is demonstrated that energy-filtered transmission electron microscope enables following of in situ changes of the Ca-L2,3 edge which can originate from variations in both local symmetry and bond lengths. Low accelerating voltages of 20 and 40 kV slow down radiation damage effects and enable study of the start and finish of phase transformations. We observed electron beam-induced phase transformation of single crystalline calcite (CaCO3) to polycrystalline calcium oxide (CaO) which occurs in different stages. The coordination of Ca in calcite is close to an octahedral one streched along the direction. Changes during phase transformation to an octahedral coordination of Ca in CaO go along with a bond length increase by 5 pm, where oxygen is preserved as a binding partner. Electron loss near-edge structure of the Ca-L2,3 edge show four separated peaks, which all shift toward lower energies during phase transformation at the same time the energy level splitting increases. We suggest that these changes can be mainly addressed to the change of the bond length on the order of picometers. An important pre-condition for such studies is stability of the energy drift in the range of meV over at least 1 h, which is achieved with the sub-Ångström low-voltage transmission electron microscope I prototype microscope.

  17. Dielectric multilayer beam splitter with differential phase shift on transmission and reflection for division-of-amplitude photopolarimeter.

    Science.gov (United States)

    Yuan, Wenjia; Shen, Weidong; Zhang, Yueguang; Liu, Xu

    2014-05-05

    Dielectric multilayer beam splitter with differential phase shift on transmission and reflection for division-of-amplitude photopolarimeter (DOAP) was presented for the first time to our knowledge. The optimal parameters for the beam splitter are Tp = 78.9%, Ts = 21.1% and Δr - Δt = π/2 at 532nm at an angle of incidence of 45°. Multilayer anti-reflection coating with low phase shift was applied to reduce the backside reflection. Different design strategies that can achieve all optimal targets at the wavelength were tested. Two design methods were presented to optimize the differential phase shift. The samples were prepared by ion beam sputtering (IBS). The experimental results show good agreement with those of the design. The ellipsometric parameters of samples were measured in reflection (ψr, Δr) = (26.5°, 135.1°) and (28.2°, 133.5°), as well as in transmission (ψt, Δt) = (62.5°, 46.1°) and (63.5°, 46°) at 532.6nm. The normalized determinant of instrument matrix to evaluate the performance of samples is respectively 0.998 and 0.991 at 532.6nm.

  18. Prototype Digital Beam Position and Phase Monitor for the 100-MeV Proton Linac of PEFP

    CERN Document Server

    Yu In Ha; Kim, Sung-Chul; Park, In-Soo; Park, Sung-Ju; Tae Kim, Do

    2005-01-01

    The PEFP (Proton Engineering Frontier Project) at the KAERI (Korea Atomic Energy Research Institute) is building a high-power proton linear accelerator aiming to generate 100-MeV proton beams with 20-mA peak current (pulse width and max. repetition rate of 1 ms and 120 Hz respectively). We are developing a prototype digital BPPM (Beam Position and Phase Monitor) for the PEFP linac utilizing the digital technology with field programmable gate array (FPGA). The RF input signals are down converted to 10 MHz and sampled at 40 MHz with 14-bit ADC to produce I and Q data streams. The system is designed to provide a position and phase resolution of 0.1% and 0.1? RMS respectively. The fast digital processing is networked to the EPICS-based control system with an embedded processor (Blackfin). In this paper, the detailed description of the prototype digital beam position and phase monitor will be described with the performance test results.

  19. Longitudinal motion in high current ion beams: a self-consistent phase space distribution with an envelope equation

    International Nuclear Information System (INIS)

    Neuffer, D.

    1979-03-01

    Many applications of particle acceleration, such as heavy ion fusion, require longitudinal bunching of a high intensity particle beam to extremely high particle currents with correspondingly high space charge forces. This requires a precise analysis of longitudinal motion including stability analysis. Previous papers have treated the longitudinal space charge force as strictly linear, and have not been self-consistent; that is, they have not displayed a phase space distribution consistent with this linear force so that the transport of the phase space distribution could be followed, and departures from linearity could be analyzed. This is unlike the situation for transverse phase space where the Kapchinskij--Vladimirskij (K--V) distribution can be used as the basis of an analysis of transverse motion. In this paper a self-consistent particle distribution in longitudinal phase space is derived which is a solution of the Vlasov equation and an envelope equation for this solution is derived

  20. Deuterium pass through target

    International Nuclear Information System (INIS)

    Alger, D.L.

    1975-01-01

    A neutron emitting target is described for use in neutron generating apparatus including a deuteron source and an accelerator vacuum chamber. The target consists of a tritium-containing target layer, a deuteron accumulation layer, and a target support containing passages providing communication between the accumulation layer and portions of the surface of the support exposed to the accelerator vacuum chamber. With this arrangement, deuterons passing through the target layer and implanting in and diffusing through the accumulation layer, diffuse into the communicating passages and are returned to the accelerator vacuum chamber. The invention allows the continuous removal of deuterons from the target in conventional water cooled neutron generating apparatus. Preferably, the target is provided with thin barrier layers to prevent undesirable tritium diffusion out of the target layer, as well as deuteron diffusion into the target layer

  1. Relation between the occurrence of Burnout and differential pressure fluctuation characteristics caused by the disturbance waves passing by a flow obstacle in a vertical boiling two-phase upward flow in a narrow annular channel

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Shoji [Yokohama National University, Yokohama 240-8501 (Japan)]. E-mail: morisho@ynu.ac.jp; Fukano, Tohru [Kurume Institute of University, Fukuoka 830-0052 (Japan)]. E-mail: fukanot@cc.kurume-it.ac.jp

    2006-05-15

    If a flow obstacle such as a spacer is placed in a boiling two-phase flow within a channel, the temperature on the surface of the heating tube is severely affected by the existence of the spacer. Under certain conditions the spacer has a cooling effect, and under other conditions the spacer causes dryout of the cooling water film on the heating surface, resulting in burnout of the tube. The burnout mechanism near the spacer, however, remains unclear. In a previous paper (Fukano, T., Mori, S., Akamatsu, S., Baba, A., 2002. Relation between temperature fluctuation of a heating surface and generation of drypatch caused by a cylindrical spacer in a vertical boiling two-phase upward flow in a narrow annular channel. Nucl. Eng. Des. 217, 81-90), we reported that the disturbance wave has a significant effect on dryout occurrence. Therefore, in the present paper, the relation between dryout, burnout occurrence, and interval between two successive disturbance waves obtained from the differential pressure fluctuation caused by the disturbance waves passing by a spacer, is further discussed in detail.

  2. Relation between the occurrence of Burnout and differential pressure fluctuation characteristics caused by the disturbance waves passing by a flow obstacle in a vertical boiling two-phase upward flow in a narrow annular channel

    International Nuclear Information System (INIS)

    Mori, Shoji; Fukano, Tohru

    2006-01-01

    If a flow obstacle such as a spacer is placed in a boiling two-phase flow within a channel, the temperature on the surface of the heating tube is severely affected by the existence of the spacer. Under certain conditions the spacer has a cooling effect, and under other conditions the spacer causes dryout of the cooling water film on the heating surface, resulting in burnout of the tube. The burnout mechanism near the spacer, however, remains unclear. In a previous paper (Fukano, T., Mori, S., Akamatsu, S., Baba, A., 2002. Relation between temperature fluctuation of a heating surface and generation of drypatch caused by a cylindrical spacer in a vertical boiling two-phase upward flow in a narrow annular channel. Nucl. Eng. Des. 217, 81-90), we reported that the disturbance wave has a significant effect on dryout occurrence. Therefore, in the present paper, the relation between dryout, burnout occurrence, and interval between two successive disturbance waves obtained from the differential pressure fluctuation caused by the disturbance waves passing by a spacer, is further discussed in detail

  3. High peak-power kilohertz laser system employing single-stage multi-pass amplification

    Science.gov (United States)

    Shan, Bing; Wang, Chun; Chang, Zenghu

    2006-05-23

    The present invention describes a technique for achieving high peak power output in a laser employing single-stage, multi-pass amplification. High gain is achieved by employing a very small "seed" beam diameter in gain medium, and maintaining the small beam diameter for multiple high-gain pre-amplification passes through a pumped gain medium, then leading the beam out of the amplifier cavity, changing the beam diameter and sending it back to the amplifier cavity for additional, high-power amplification passes through the gain medium. In these power amplification passes, the beam diameter in gain medium is increased and carefully matched to the pump laser's beam diameter for high efficiency extraction of energy from the pumped gain medium. A method of "grooming" the beam by means of a far-field spatial filter in the process of changing the beam size within the single-stage amplifier is also described.

  4. High-Speed, Low-Power ADC for Digital Beam Forming (DBF) Systems, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Ridgetop Group will design a high-speed, low-power silicon germanium (SiGe)-based, analog-to-digital converter (ADC) to be a key element for digital beam forming...

  5. Beam loading

    OpenAIRE

    Boussard, Daniel

    1987-01-01

    We begin by giving a description of the radio-frequency generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, radio-frequency feedback and feedforward are described. Examples of digital radio-frequency phase and amplitude control for the special case of superco...

  6. Mechanical beam isolator

    International Nuclear Information System (INIS)

    Post, R.F.; Vann, C.S.

    1996-10-01

    Back-reflections from a target, lenses, etc. can gain energy passing backwards through a laser just like the main beam gains energy passing forwards. Unless something blocks these back-reflections early in their path, they can seriously damage the laser. A Mechanical Beam Isolator is a device that blocks back-reflections early, relatively inexpensively, and without introducing aberrations to the laser beam

  7. Precision improving of double beam shadow moiré interferometer by phase shifting interferometry for the stress of flexible substrate

    Science.gov (United States)

    Huang, Kuo-Ting; Chen, Hsi-Chao; Lin, Ssu-Fan; Lin, Ke-Ming; Syue, Hong-Ye

    2012-09-01

    While tin-doped indium oxide (ITO) has been extensively applied in flexible electronics, the problem of the residual stress has many obstacles to overcome. This study investigated the residual stress of flexible electronics by the double beam shadow moiré interferometer, and focused on the precision improvement with phase shifting interferometry (PSI). According to the out-of-plane displacement equation, the theoretical error depends on the grating pitch and the angle between incident light and CCD. The angle error could be reduced to 0.03% by the angle shift of 10° as a result of the double beam interferometer was a symmetrical system. But the experimental error of the double beam moiré interferometer still reached to 2.2% by the noise of the vibration and interferograms. In order to improve the measurement precision, PSI was introduced to the double shadow moiré interferometer. Wavefront phase was reconstructed by the five interferograms with the Hariharan algorithm. The measurement results of standard cylinder indicating the error could be reduced from 2.2% to less than 1% with PSI. The deformation of flexible electronic could be reconstructed fast and calculated the residual stress with the Stoney correction formula. This shadow moiré interferometer with PSI could improve the precision of residual stress for flexible electronics.

  8. TU-AB-BRC-05: Creation of a Monte Carlo TrueBeam Model by Reproducing Varian Phase Space Data

    International Nuclear Information System (INIS)

    O’Grady, K; Davis, S; Seuntjens, J

    2016-01-01

    Purpose: To create a Varian TrueBeam 6 MV FFF Monte Carlo model using BEAMnrc/EGSnrc that accurately reproduces the Varian representative dataset, followed by tuning the model’s source parameters to accurately reproduce in-house measurements. Methods: A BEAMnrc TrueBeam model for 6 MV FFF has been created by modifying a validated 6 MV Varian CL21EX model. Geometric dimensions and materials were adjusted in a trial and error approach to match the fluence and spectra of TrueBeam phase spaces output by the Varian VirtuaLinac. Once the model’s phase space matched Varian’s counterpart using the default source parameters, it was validated to match 10 × 10 cm"2 Varian representative data obtained with the IBA CC13. The source parameters were then tuned to match in-house 5 × 5 cm"2 PTW microDiamond measurements. All dose to water simulations included detector models to include the effects of volume averaging and the non-water equivalence of the chamber materials, allowing for more accurate source parameter selection. Results: The Varian phase space spectra and fluence were matched with excellent agreement. The in-house model’s PDD agreement with CC13 TrueBeam representative data was within 0.9% local percent difference beyond the first 3 mm. Profile agreement at 10 cm depth was within 0.9% local percent difference and 1.3 mm distance-to-agreement in the central axis and penumbra regions, respectively. Once the source parameters were tuned, PDD agreement with microDiamond measurements was within 0.9% local percent difference beyond 2 mm. The microDiamond profile agreement at 10 cm depth was within 0.6% local percent difference and 0.4 mm distance-to-agreement in the central axis and penumbra regions, respectively. Conclusion: An accurate in-house Monte Carlo model of the Varian TrueBeam was achieved independently of the Varian phase space solution and was tuned to in-house measurements. KO acknowledges partial support by the CREATE Medical Physics Research

  9. A Hardware transverse beam frequency response simulator

    International Nuclear Information System (INIS)

    Ning, J.; Tan, C.Y.

    2005-01-01

    We built an electronic instrument that can mimic the transverse beam frequency response. The instrument consists of (1) a time delay circuit with an analog-to-digital converter (ADC) which contains a first-in-first-out random assess memory (FIFO RAM) and a digital-to-analog converter (DAC); (2) a variable phase shifter circuit which is based on an all pass filter with a bandwidth of 25kHz to 30kHz and (3) a commutating filter which is a nonlinear band pass filter. With this instrument, we can dynamically adjust the betatron tune, the synchrotron tune, and the chromaticity. Using this instrument, we are able to test other beam systems without using actual beam

  10. Generation of ultra-long pure magnetization needle and multiple spots by phase modulated doughnut Gaussian beam

    Science.gov (United States)

    Udhayakumar, M.; Prabakaran, K.; Rajesh, K. B.; Jaroszewicz, Z.; Belafhal, Abdelmajid; Velauthapillai, Dhayalan

    2018-06-01

    Based on vector diffraction theory and inverse Faraday effect (IFE), the light induced magnetization distribution of a tightly focused azimuthally polarized doughnut Gaussian beam superimposed with a helical phase and modulated by an optimized multi belt complex phase filter (MBCPF) is analysed numerically. It is noted that by adjusting the radii of different rings of the complex phase filter, one can achieve many novel magnetization focal distribution such as sub wavelength scale (0.29λ) and super long (52.2λ) longitudinal magnetic probe suitable for all optical magnetic recording and the formation of multiple magnetization chain with four, six and eight sub-wavelength spherical magnetization spots suitable for multiple trapping of magnetic particles are achieved.

  11. Modeling of Focused Acoustic Field of a Concave Multi-annular Phased Array Using Spheroidal Beam Equation

    International Nuclear Information System (INIS)

    Yu Lili; Shou Wende; Hui Chun

    2012-01-01

    A theoretical model of focused acoustic field for a multi-annular phased array on concave spherical surface is proposed. In this model, the source boundary conditions of the spheroidal beam equation (SBE) for multi-annular phased elements are studied. Acoustic field calculated by the dynamic focusing model of SBE is compared with numerical results of the O'Neil and Khokhlov-Zabolotskaya-Kuznetsov (KZK) model, respectively. Axial dynamic focusing and the harmonic effects are presented. The results demonstrate that the dynamic focusing model of SBE is good valid for a concave multi-annular phased array with a large aperture angle in the linear or nonlinear field. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  12. Microstructures and phase formations in the surface layer of an AISI D2 steel treated with pulsed electron beam

    International Nuclear Information System (INIS)

    Zou, J.X.; Grosdidier, T.; Zhang, K.M.; Gao, B.; Hao, S.Z.; Dong, C.

    2007-01-01

    The nanostructures and metastable phase transformations in the surface layer of an AISI D2 steel treated with high current pulsed electron beam (HCPEB) were investigated. The surface structure is marked by two distinct features, i.e. the formation of sub-micrometer fine austenite γ grains (50-150 nm), and the disappearance of carbides via dissolution and crater eruption. The γ phase directly grows from the melt and is retained down to room temperature. Although the cooling rate is as high as 10 7 K/s in our case, the martensitic transformation could completely be suppressed. Such an effect is due to the increased stability of the austenite phase through grain refinement and chemistry modification

  13. Upgrade of the TCV tokamak, first phase: Neutral beam heating system

    Energy Technology Data Exchange (ETDEWEB)

    Karpushov, Alexander N., E-mail: alexander.karpushov@epfl.ch [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Alberti, Stefano; Chavan, René [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Davydenko, Vladimir I. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Duval, Basil P. [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Ivanov, Alexander A. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Fasel, Damien; Fasoli, Ambrogio [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Gorbovsky, Aleksander I. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Goodman, Timothy [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Kolmogorov, Vyacheslav V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Martin, Yves; Sauter, Olivier [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, CH-1015 Lausanne (Switzerland); Sorokin, Aleksey V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); and others

    2015-10-15

    Highlights: • Widening the parameter range of reactor relevant regimes on the TCV tokamak. • Installation of 1 MW, 30 keV neutral beam, direct ion heating, access to T{sub i}/T{sub e} ≥ 1. • ASTRA simulation of plasma response to NB and EC heating in different regimes. • Specific low divergency neutral beam injector with tunable beam power and energy. - Abstract: Experiments on TCV are designed to complement the work at large integrated tokamak facilities (such as JET) to provide a stepwise approach to extrapolation to ITER and DEMO in areas where medium-size tokamaks can often exploit their experimental capabilities and flexibility. Improving the understanding and control requirements of burning plasmas is a major scientific challenge, requiring access to plasma regimes and configurations with high normalized plasma pressure and a wide range of ion to electron temperature ratios, including T{sub e}/T{sub i} ∼ 1. These conditions will be explored by adding a 1 MW neutral heating beam to TCV's auxiliary for direct ion heating (2015) and increasing the ECH power injected in X-mode at the third harmonic (2 MW in 2015–2016). The manufacturing of the neutral beam injector was launched in 2014.

  14. Beam Manipulation with an RF Dipole

    International Nuclear Information System (INIS)

    Bai, M.

    1999-01-01

    Coherent betatron motion adiabatically excited by an RF dipole has been successfully employed to overcome strong intrinsic spin depolarization resonances in the AGS, while a solenoid partial snake has been used to correct imperfection spin resonances. The experimental results showed that a full spin flip was obtained in passing through an intrinsic spin resonance when all the beam particles were forced to oscillate coherently at a large amplitude without diluting the beam emittance. With this method, they have successfully accelerated polarized beam up to 23.5 GeV/c. A new type of second order spin resonances was also discovered. As a non-destructive manipulation, this method can also be used for nonlinear beam dynamics studies and beam diagnosis such as measuring phase advance and betatron amplitude function

  15. Two-beam ultrabroadband coherent anti-Stokes Raman spectroscopy for high resolution gas-phase multiplex imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bohlin, Alexis; Kliewer, Christopher J., E-mail: cjkliew@sandia.gov [Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550 (United States)

    2014-01-20

    We propose and develop a method for wideband coherent anti-Stokes Raman spectroscopy (CARS) in the gas phase and demonstrate the single-shot measurement of N{sub 2}, H{sub 2}, CO{sub 2}, O{sub 2}, and CH{sub 4}. Pure-rotational and vibrational O-, Q-, and S- branch spectra are collected simultaneously, with high spectral and spatial resolution, and within a single-laser-shot. The relative intensity of the rotational and vibrational signals can be tuned arbitrarily using polarization techniques. The ultrashort 7 fs pump and Stokes pulses are automatically overlapped temporally and spatially using a two-beam CARS technique, and the crossed probe beam allows for excellent spatial sectioning of the probed location.

  16. Two-beam ultrabroadband coherent anti-Stokes Raman spectroscopy for high resolution gas-phase multiplex imaging

    International Nuclear Information System (INIS)

    Bohlin, Alexis; Kliewer, Christopher J.

    2014-01-01

    We propose and develop a method for wideband coherent anti-Stokes Raman spectroscopy (CARS) in the gas phase and demonstrate the single-shot measurement of N 2 , H 2 , CO 2 , O 2 , and CH 4 . Pure-rotational and vibrational O-, Q-, and S- branch spectra are collected simultaneously, with high spectral and spatial resolution, and within a single-laser-shot. The relative intensity of the rotational and vibrational signals can be tuned arbitrarily using polarization techniques. The ultrashort 7 fs pump and Stokes pulses are automatically overlapped temporally and spatially using a two-beam CARS technique, and the crossed probe beam allows for excellent spatial sectioning of the probed location

  17. On the (Frequency) Modulation of Coupled Oscillator Arrays in Phased Array Beam Control

    Science.gov (United States)

    Pogorzelski, R.; Acorn, J.; Zawadzki, M.

    2000-01-01

    It has been shown that arrays of voltage controlled oscillators coupled to nearest neighbors can be used to produce useful aperture phase distributions for phased array antennas. However, placing information of the transmitted signal requires that the oscillations be modulated.

  18. Reconstruction of Sound Source Pressures in an Enclosure Using the Phased Beam Tracing Method

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho; Ih, Jeong-Guon

    2009-01-01

    . First, surfaces of an extended source are divided into reasonably small segments. From each source segment, one beam is projected into the field and all emitted beams are traced. Radiated beams from the source reach array sensors after traveling various paths including the wall reflections. Collecting...... all the pressure histories at the field points, source-observer relations can be constructed in a matrix-vector form for each frequency. By multiplying the measured field data with the pseudo-inverse of the calculated transfer function, one obtains the distribution of source pressure. An omni......-directional sphere and a cubic source in a rectangular enclosure were taken as examples in the simulation tests. A reconstruction error was investigated by Monte Carlo simulation in terms of field point locations. When the source information was reconstructed by the present method, it was shown that the sound power...

  19. Hydrogen-Induced Phase Transformation and Microstructure Evolution for Ti-6Al-4V Parts Produced by Electron Beam Melting

    Directory of Open Access Journals (Sweden)

    Natalia Pushilina

    2018-04-01

    Full Text Available In this paper, phase transitions and microstructure evolution in titanium Ti-6Al-4V alloy parts produced by electron beam melting (EBM under hydrogenation was investigated. Hydrogenation was carried out at the temperature of 650 °C to the absolute hydrogen concentrations in the samples of 0.29, 0.58, and 0.90 wt. %. Comparative analysis of microstructure changes in Ti-6Al-4V alloy parts was performed using scanning electron microscopy (SEM, transmission electron microscopy (TEM, and X-ray diffraction (XRD. Furthermore, in-situ XRD was used to investigate the phase transitions in the samples during hydrogenation. The structure of Ti-6Al-4V parts produced by EBM is represented by the α phase plates with the transverse length of 0.2 μm, the β phase both in the form of plates and globular grains, and metastable α″ and ω phases. Hydrogenation to the concentration of 0.29 wt. % leads to the formation of intermetallic Ti3Al phase. The dimensions of intermetallic Ti3Al plates and their volume fraction increase significantly with hydrogen concentration up to 0.58 wt. % along with precipitation of nano-sized crystals of titanium δ hydrides. Individual Ti3Al plates decay into nanocrystals with increasing hydrogen concentration up to 0.9 wt. % accompanied by the increase of proportion and size of hydride plates. Hardness of EBM Ti-6Al-4V alloy decreases with hydrogen content.

  20. A facility for liquid-phase radiation experiments on heavy ion beams

    International Nuclear Information System (INIS)

    Stuglik, Z.; Zvara, I.; Yakushev, A.B.; Timokhin, S.N.

    1992-01-01

    The title facility is described, installed on a beam line of the 4-meter U-400 cyclotron in the Flerov Laboratory of Nuclear Reactions, JINR, Dubna. The accelerator provides intermediate energy (some 10 MeV/nucleon) beams of ions from Li to Xe. Preliminary results on the radiolysis of two liquid systems -Fricke solution and malachite green in ethanol - by 11 B, 24 Mg, and 40 Ca ions are presented. Some experimental problems and uncertainities faced at the quantitative evaluation of the data are discussed. 62 refs.; 5 figs.; 2 tabs

  1. A facility for liquid-phase radiation experiments on heavy ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Stuglik, Z; Zvara, I; Yakushev, A B; Timokhin, S N

    1993-12-31

    The title facility is described, installed on a beam line of the 4-meter U-400 cyclotron in the Flerov Laboratory of Nuclear Reactions, JINR, Dubna. The accelerator provides intermediate energy (some 10 MeV/nucleon) beams of ions from Li to Xe. Preliminary results on the radiolysis of two liquid systems -Fricke solution and malachite green in ethanol - by {sup 11}B, {sup 24}Mg, and {sup 40}Ca ions are presented. Some experimental problems and uncertainities faced at the quantitative evaluation of the data are discussed. 62 refs.; 5 figs.; 2 tabs.

  2. Study on radial-phase motion of a beam in the 3 cm electron linear accelerator

    International Nuclear Information System (INIS)

    Polyakov, V.A.; Shchedrin, I.S.

    1982-01-01

    Longitudinal and transverse dynamics of particles in a 3 cm electron linear accelerator (ELA) are. considered. Electron motion in the source and in the section before inlet onto the accelerating section, effect of the wave type input transformer as well as the effect of deviations of parameters of ELA supply system on oUtput characteristics of the beam have been taken into account. The results obtained permitted to explain a comparatively small value of accelerated current at the output of the LAEU-31M (38 m A). Recommendations on improvement of beam passogein the accelerating section are developed based on computerized calculations

  3. Determination of thermal diffusivity at low temperature using the two-beam phase-lag photoacoustic method with observation of phase-transitions

    International Nuclear Information System (INIS)

    Jorge, M.P.P.

    1992-01-01

    This study consists of the determination of thermal diffusivity int he temperature range from 77 K to 300 K by the two-beam phase-lag photoacoustic method. Room temperature measurements of NTD (neutron transmutation doping) silicon suggest that the doping process does not affect its thermal properties. For the superconductor Y Ba 2 Cu 3 O 7 - x it has been verified that the sample density affects its thermal diffusivity. The validity of the experimental method on the Li K SO 4 crystal has been examined by using the thermal diffusivity of a Li F crystal and an Y 2 O 3 ceramic, at room temperature. The behavior of the thermal diffusivity as a function of the temperature for the Li K SO 4 crystal shows two anomalies which correspond at phase-transitions of this crystal in the studied temperature range. (author)

  4. Beam pattern improvement by compensating array nonuniformities in a guided wave phased array

    International Nuclear Information System (INIS)

    Kwon, Hyu-Sang; Lee, Seung-Seok; Kim, Jin-Yeon

    2013-01-01

    This paper presents a simple data processing algorithm which can improve the performance of a uniform circular array based on guided wave transducers. The algorithm, being intended to be used with the delay-and-sum beamformer, effectively eliminates the effects of nonuniformities that can significantly degrade the beam pattern. Nonuniformities can arise intrinsically from the array geometry when the circular array is transformed to a linear array for beam steering and extrinsically from unequal conditions of transducers such as element-to-element variations of sensitivity and directivity. The effects of nonuniformities are compensated by appropriately imposing weight factors on the elements in the projected linear array. Different cases are simulated, where the improvements of the beam pattern, especially the level of the highest sidelobe, are clearly seen, and related issues are discussed. An experiment is performed which uses A0 mode Lamb waves in a steel plate, to demonstrate the usefulness of the proposed method. The discrepancy between theoretical and experimental beam patterns is explained by accounting for near-field effects. (paper)

  5. Influence of electron beam exposure on crystallization of phase-change materials

    NARCIS (Netherlands)

    Pandian, Ramanathaswamy; Kooi, Bart J.; De Hosson, Jeff Th. M.; Pauza, Andrew

    2007-01-01

    Isothermal crystallization of amorphous SbxTe films capped with ZnS-SiO2 or GeCrN layers was performed using in situ heating within a transmission electron microscope. The effect of the electron beam of the microscope on the crystallization process was investigated. It was found that electron

  6. Transverse to longitudinal phase space coupling in an electron beam for suppression of microbunching instability

    Directory of Open Access Journals (Sweden)

    Dazhang Huang

    2016-10-01

    Full Text Available The microbunching instability developed during the beam compression process in the linear accelerator (LINAC of a free-electron laser (FEL facility has always been a problem that degrades the lasing performance, and even no FEL is able to be produced if the beam quality is destroyed too much by the instability. A common way to suppress the microbunching instability is to introduce extra uncorrelated energy spread by the laser heater that heats the beam through the interaction between the electron and laser beam, as what has been successfully implemented in the Linac Coherent Light Source and Fermi@Elettra. In this paper, a simple and effective scheme is proposed to suppress the microbunching instability by adding two transverse gradient undulators (TGU before and after the magnetic bunch compressor. The additional uncorrelated energy spread and the density mixing from the transverse spread brought up by the first TGU results in significant suppression of the instability. Meanwhile, the extra slice energy spread and the transverse emittance can also be effectively recovered by the second TGU. The magnitude of the suppression can be easily controlled by varying the strength of the magnetic fields of the TGUs. Theoretical analysis and numerical simulations demonstrate the capability of the proposed technique in the LINAC of an x-ray free-electron laser facility.

  7. Synthesis of dynamic phase profile by the correlation technique for spatial control of optical beams in multiplexing and switching

    Science.gov (United States)

    Bugaychuk, Svitlana A.; Gnatovskyy, Vladimir O.; Sidorenko, Andrey V.; Pryadko, Igor I.; Negriyko, Anatoliy M.

    2015-11-01

    New approach for the correlation technique, which is based on multiple periodic structures to create a controllable angular spectrum, is proposed and investigated both theoretically and experimentally. The transformation of an initial laser beam occurs due to the actions of consecutive phase periodic structures, which may differ by their parameters. Then, after the Fourier transformation of a complex diffraction field, the output diffraction orders will be changed both by their intensities and by their spatial position. The controllable change of output angular spectrum is carried out by a simple control of the parameters of the periodic structures. We investigate several simple examples of such management.

  8. Abstracts of 4. International Workshop on Molecular Beam Epitaxy and Vapour Phase Epitaxy Growth Physics and Technology

    International Nuclear Information System (INIS)

    2001-01-01

    4. International Workshop on Molecular Beam Epitaxy and Vapour Phase Epitaxy Growth Physics and Technology is the periodically held forum for discussion the problems connected with manufacturing of different nanostructures (thin films, quantum wells, quantum dots) needed in microelectronics. Preparation of such materials with desirable optical, electrical and magnetic properties being determined by their chemical composition and crystal structure has been discussed in detail during the workshop sessions. Optimization of crystal growth methods such as VPE and MBE from the view point of obtained material properties has also been extensively discussed

  9. Generation of electron Airy beams.

    Science.gov (United States)

    Voloch-Bloch, Noa; Lereah, Yossi; Lilach, Yigal; Gover, Avraham; Arie, Ady

    2013-02-21

    Within the framework of quantum mechanics, a unique particle wave packet exists in the form of the Airy function. Its counterintuitive properties are revealed as it propagates in time or space: the quantum probability wave packet preserves its shape despite dispersion or diffraction and propagates along a parabolic caustic trajectory, even though no force is applied. This does not contradict Newton's laws of motion, because the wave packet centroid propagates along a straight line. Nearly 30 years later, this wave packet, known as an accelerating Airy beam, was realized in the optical domain; later it was generalized to an orthogonal and complete family of beams that propagate along parabolic trajectories, as well as to beams that propagate along arbitrary convex trajectories. Here we report the experimental generation and observation of the Airy beams of free electrons. These electron Airy beams were generated by diffraction of electrons through a nanoscale hologram, which imprinted on the electrons' wavefunction a cubic phase modulation in the transverse plane. The highest-intensity lobes of the generated beams indeed followed parabolic trajectories. We directly observed a non-spreading electron wavefunction that self-heals, restoring its original shape after passing an obstacle. This holographic generation of electron Airy beams opens up new avenues for steering electronic wave packets like their photonic counterparts, because the wave packets can be imprinted with arbitrary shapes or trajectories.

  10. Integrated Cu-based TM-pass polarizer using CMOS technology platform

    KAUST Repository

    Ng, Tien Khee; Khan, Mohammed Zahed Mustafa; Ooi, Boon S.

    2010-01-01

    A transverse-magnetic-pass (TM-pass) copper (Cu) polarizer is proposed and analyzed using the previously published two-dimensional Method-of-Lines beam-propagation model. The proposed polarizer exhibits a simulated high-pass filter characteristics

  11. A phase II study of V-BEAM as conditioning regimen before second auto-SCT for multiple myeloma.

    Science.gov (United States)

    Wang, T-F; Fiala, M A; Cashen, A F; Uy, G L; Abboud, C N; Fletcher, T; Wu, N; Westervelt, P; DiPersio, J F; Stockerl-Goldstein, K E; Vij, R

    2014-11-01

    High-dose melphalan has been the standard conditioning regimen for auto-SCT in multiple myeloma (MM) for decades. A more effective conditioning regimen may induce deeper responses and longer remission duration. It is especially needed in the setting of second auto-SCT, which rarely achieves comparable results with the first auto-SCT using the same conditioning regimen. Here we conducted a phase II study to investigate the efficacy and safety of a conditioning regimen V-BEAM (bortezomib-BEAM) before second auto-SCT for multiple myeloma. Ten patients were enrolled from September 2012 to May 2013. The CR rate at day +100 after auto-SCT was 75%; all except for one patient remained in remission after a median follow-up of 6 months. Three patients developed Clostridium difficile infection. Two patients died within the first 30 days of auto-SCT from neutropenic colitis and overwhelming sepsis, respectively. Due to the high rate of morbidity and mortality, the study was terminated after 10 patients. In summary, although the conditioning regimen V-BEAM before second auto-SCT for MM provided promising responses, it was associated with unexpected treatment-related toxicity and should not be investigated further without modifications.

  12. Beam loading

    CERN Document Server

    Gamp, Alexander

    2013-01-01

    We begin by giving a description of the radio-frequency generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, radio-frequency feedback and feedforward are described. Examples of digital radio-frequency phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed.

  13. Beam loading

    International Nuclear Information System (INIS)

    Gamp, Alexander

    2013-01-01

    We begin by giving a description of the radio-frequency generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, radio-frequency feedback and feedforward are described. Examples of digital radio-frequency phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed. (author)

  14. Electrical performance of phase change memory cells with Ge3Sb2Te6 deposited by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Boschker, Jos E.; Riechert, Henning; Calarco, Raffaella; Boniardi, Mattia; Redaelli, Andrea

    2015-01-01

    Here, we report on the electrical characterization of phase change memory cells containing a Ge 3 Sb 2 Te 6 (GST) alloy grown in its crystalline form by Molecular Beam Epitaxy (MBE). It is found that the high temperature growth on the amorphous substrate results in a polycrystalline film exhibiting a rough surface with a grain size of approximately 80–150 nm. A detailed electrical characterization has been performed, including I-V characteristic curves, programming curves, set operation performance, crystallization activation at low temperature, and resistance drift, in order to determine the material related parameters. The results indicate very good alignment of the electrical parameters with the current state-of-the-art GST, deposited by physical vapor deposition. Such alignment enables a possible employment of the MBE deposition technique for chalcogenide materials in the phase change memory technology, thus leading to future studies of as-deposited crystalline chalcogenides as integrated in electrical vehicles

  15. Diffraction study of duty-cycle error in ferroelectric quasi-phase-matching gratings with Gaussian beam illumination

    Science.gov (United States)

    Dwivedi, Prashant Povel; Kumar, Challa Sesha Sai Pavan; Choi, Hee Joo; Cha, Myoungsik

    2016-02-01

    Random duty-cycle error (RDE) is inherent in the fabrication of ferroelectric quasi-phase-matching (QPM) gratings. Although a small RDE may not affect the nonlinearity of QPM devices, it enhances non-phase-matched parasitic harmonic generations, limiting the device performance in some applications. Recently, we demonstrated a simple method for measuring the RDE in QPM gratings by analyzing the far-field diffraction pattern obtained by uniform illumination (Dwivedi et al. in Opt Express 21:30221-30226, 2013). In the present study, we used a Gaussian beam illumination for the diffraction experiment to measure noise spectra that are less affected by the pedestals of the strong diffraction orders. Our results were compared with our calculations based on a random grating model, demonstrating improved resolution in the RDE estimation.

  16. Removal of chlorinated organic compounds from gas phase using electron beam technology

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Y.; Bulka, S.; Zimek, A. [Institute of Nuclear Chemistry and Technology, Warsaw (Poland); Chmielewski, A. G. [Institute of Nuclear Chemistry and Technology, Warsaw (Poland); Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warsaw (Poland)

    2011-07-01

    Selected chlorinated organic compounds (Cl-HC), which are emitted from coal fired power plants, waste incinerators, chemical industry etc., are very harmful to the environment and human’s health. Some of them are listed as carcinogenic compounds by USA EPA. Recent studies show that some chlorinated organic compounds are suspected to be precursors for dioxins formation. Chlorinated organic compounds decomposition in air in an electron beam (EB) generated plasma reactor technology was studied. We selected cis-dichloroethylene (cis-DCE), 1,4-dichlorobenznene(1,4-DCB), 1-chloronaphthalene as studied objects. It is found that chlorinated organic compounds can be decomposed in an electron beam generated plasma reactor. The order of decomposition efficiency of these compounds are: cis-DCE > 1,4-DCB> 1-chloronaphthalene. (author)

  17. Dynamics of Longitudinal Phase-Space Modulations in an rf Compressor for Electron Beams

    International Nuclear Information System (INIS)

    Venturini, M.; Migliorati, M.; Ronsivalle, C.; Ferrario, M.; Vaccarezza, C.

    2010-01-01

    Free Electron Lasers (FELs) operating in the UV or x-ray radiation spectrum require peak beam currents that are generally higher than those obtainable by present electron sources, thus making bunch compression necessary. Compression, however, may heighten the effects of collective forces and degrade the beam quality. In this paper they provide a framework for investigating some of these effects in rf compressors by focusing on the longitudinal dynamics of small-amplitude density perturbations, which have the potential to cause the disruptive appearance of the so-called microbunching instability. They develop a linear theory valid for low-to-moderate compression factors under the assumption of a 1D impedance model of longitudinal space charge and provide validation against macroparticle simulations.

  18. Affects of binary and continuous phase modulations on the structure of Bessel beams

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2010-09-01

    Full Text Available The authors implement a novel technique to operate a phase-only spatial light modulator (SLM) in amplitude mode, allowing them to reproduce Durnin’s ring slit on a liquid crystal display (LCD). The affects of binary and continuous phase modulations...

  19. Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs

    Energy Technology Data Exchange (ETDEWEB)

    Mangum, John S.; Chan, Lisa H.; Schmidt, Ute; Garten, Lauren M.; Ginley, David S.; Gorman, Brian P.

    2018-05-01

    Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In this work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice.

  20. Formation of structure, phase composition and properties of electro explosion resistant coatings using electron-beam processing

    International Nuclear Information System (INIS)

    Romanov, Denis A.; Sosnin, Kirill V.; Budovskikh, Evgenij A.; Gromov, Viktor E.; Semin, Alexander P.

    2014-01-01

    For the first time, the high intensity electron beam modification of electroexplosion composite coatings of MoCu, MoCCu, WCu, WCCu and TiB 2 Cu systems was done. The studies of phase and elemental composition, defective structure conditions of these coatings were carried out. The regimes of electron-beam processing making possible to form the dense, specular luster surface layers having a submicrocrystalline structure were revealed. It was established that electron-beam processing of elecroexplosion spraying of layer of elecroexplosion spraying carried out in the regime of melting results in the formation of structurally and contrationally homogeneous surface layer. Investigation of the effect of electron-beam processing of electroexplosion electroerosion resistant coatings on their tribological properties (wear resistanse and coefficient of friction) and electroerosion resistance was done. It was shown that all the examined costings demonstrate the increase of electroerosion resistance in spark erosion up to 10 times

  1. Formation of structure, phase composition and properties of electro explosion resistant coatings using electron-beam processing

    Energy Technology Data Exchange (ETDEWEB)

    Romanov, Denis A., E-mail: romanov-da@physics.sibsiu.ru, E-mail: kos2906@mail.ru, E-mail: budovskih-ea@physics.sibsiu.ru, E-mail: gromov@physics.sibsiu.ru, E-mail: da-rom@live.ru; Sosnin, Kirill V., E-mail: romanov-da@physics.sibsiu.ru, E-mail: kos2906@mail.ru, E-mail: budovskih-ea@physics.sibsiu.ru, E-mail: gromov@physics.sibsiu.ru, E-mail: da-rom@live.ru; Budovskikh, Evgenij A., E-mail: romanov-da@physics.sibsiu.ru, E-mail: kos2906@mail.ru, E-mail: budovskih-ea@physics.sibsiu.ru, E-mail: gromov@physics.sibsiu.ru, E-mail: da-rom@live.ru; Gromov, Viktor E., E-mail: romanov-da@physics.sibsiu.ru, E-mail: kos2906@mail.ru, E-mail: budovskih-ea@physics.sibsiu.ru, E-mail: gromov@physics.sibsiu.ru, E-mail: da-rom@live.ru; Semin, Alexander P., E-mail: romanov-da@physics.sibsiu.ru, E-mail: kos2906@mail.ru, E-mail: budovskih-ea@physics.sibsiu.ru, E-mail: gromov@physics.sibsiu.ru, E-mail: da-rom@live.ru [Siberian State Industrial University, Novokuznetsk, 654007 (Russian Federation)

    2014-11-14

    For the first time, the high intensity electron beam modification of electroexplosion composite coatings of MoCu, MoCCu, WCu, WCCu and TiB{sub 2}Cu systems was done. The studies of phase and elemental composition, defective structure conditions of these coatings were carried out. The regimes of electron-beam processing making possible to form the dense, specular luster surface layers having a submicrocrystalline structure were revealed. It was established that electron-beam processing of elecroexplosion spraying of layer of elecroexplosion spraying carried out in the regime of melting results in the formation of structurally and contrationally homogeneous surface layer. Investigation of the effect of electron-beam processing of electroexplosion electroerosion resistant coatings on their tribological properties (wear resistanse and coefficient of friction) and electroerosion resistance was done. It was shown that all the examined costings demonstrate the increase of electroerosion resistance in spark erosion up to 10 times.

  2. Correlative micro-diffraction and differential phase contrast study of mean inner potential and subtle beam-specimen interaction

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Mingjian, E-mail: mingjian.wu@fau.de; Spiecker, Erdmann, E-mail: erdmann.spiecker@fau.de

    2017-05-15

    Highlights: • Correlative micro-diffraction and DPC-STEM as effective and intuitive method for probing nano-scale electric fields/electrostatic potentials. • Mean inner potential accurately measured by electron refraction from cleaved crystal wedge. • Suggested a pseudo-contactless mode for probing electrostatic potential differences by considering subtle displacements of Fresnel fringes. - Abstract: We present a correlative micro-diffraction and differential phase contrast (DPC) study within scanning transmission electron microscopy (STEM) on the determination of mean inner potential (MIP) and explain the origin of subtle beam-specimen interactions at the edge of wedge-shaped crystals using both experiment and simulation. Our measurement of MIP of Si and GaAs resulted in 12.48 ± 0.22 V and 14.15 ± 0.22 V, respectively, from directly evaluating beam refraction in micro-diffraction mode. DPC-STEM measurements gave very similar values. Fresnel fringes within the diffraction disk resulting from interaction of the highly coherent electron beam with the aperture are observed and a numerical simulation scheme is implemented to reproduce the effect of the specimen on the fringe pattern. Perfect agreement between experiment and simulation has been achieved in terms of subtle displacements of the fringes upon approaching the sample edge with the electron probe. The existence of the fringes has minor effect on the DPC-STEM signal, which is well below the noise level of our setup at practically reasonable acquisition times. We suggest the possibility to perform pseudo-contactless probing of weak potential differences in beam sensitive samples by evaluating the subtle displacements of Fresnel fringes quantitatively.

  3. A double-pass interferometer for measurement of dimensional changes

    International Nuclear Information System (INIS)

    Ren, Dongmei; Lawton, K M; Miller, J A

    2008-01-01

    A double-pass interferometer was developed for measuring dimensional changes of materials in a nanoscale absolute interferometric dilatometer. This interferometer realized the double-ended measurement of a sample using a single-detection double-pass interference system. The nearly balanced design, in which the measurement beam and the reference beam have equal optical path lengths except for the path difference caused by the sample itself, makes this interferometer have high stability, which is verified by the measurement of a quasi-zero-length sample. The preliminary experiments and uncertainty analysis show that this interferometer should be able to measure dimensional changes with characteristic uncertainty at the nanometer level

  4. Electron-beam-induced structure transformation of the quasicrystalline phases of the Al 62Cu 20Co 15Si 3 alloy

    Science.gov (United States)

    Reyes-Gasga, J.; R. Garcia, G.; Jose-Yacaman, M.

    1995-02-01

    Some details on the phase transformation experienced by the quasicrystalline phases of the Al 62Cu 20Co 15Si 3 alloy under a 400 kV electron beam are given. The transition is observed in situ with a high resolution electron microscope and recorded on video tape. The results show that the electron beam radiation produces a sequence of changes similar to the ones observed in an ion-beam-induced amorphization process. Considering electron radiation damage analysis, the results agree well with the "flip-flop" model [Coddens, Bellisent, Calvayrac and Ambroise (1991) Europhys. Lett.16, 271] where the transition from a quasicrystalline phase to a crystalline phase is produced by atomic displacements but not in a cascade way.

  5. Simulations relevant to the beam instability in the foreshock

    Science.gov (United States)

    Cairns, I. H.; Nishikawa, K.-I.

    1989-01-01

    The results presently obtained from two-dimensional simulations of the reactive instability for Maxwellian beams and cutoff distributions are noted to be consistent with recent suggestions that electrons backstreaming into earth's foreshock have steep-sided cutoff distributions, which are initially unstable to the reactive instability, and that the back-reaction to the wave growth causes the instability to pass into its kinetic phase. It is demonstrated that the reactive instability is a bunching instability, and that the reactive instability saturates and passes over into the kinetic phase by particle trapping.

  6. A low background pulsed neutron polyenergetic beam

    International Nuclear Information System (INIS)

    Adib, M.; Abdelkawy, A.; Habib, N.; abuelela, M.; Wahba, M.; kilany, M.; Kalebebin, S.M.

    1992-01-01

    A low background pulsed neutron polyenergetic thermal beam at ET-R R-1 is produced by a rotor and rotating collimator suspended in magnetic fields. Each of them is mounted on its mobile platform and whose centres are 66 cm apart, rotating synchronously at speeds up to 16000 rpm. It was found that the neutron burst produced by the rotor with almost 100% transmission passes through the collimator, when the rotation phase between them is 28.8 degree Moreover the background level achieved at the detector position is low, constant and free from peaks due to gamma rays and fast neutrons accompanying the reactor thermal beam.3 fig

  7. Finite Element Models for Electron Beam Freeform Fabrication Process, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase II proposal offers to develop a comprehensive computer simulation methodology based on the finite element method for...

  8. Pattern manipulation via on-chip phase modulation between orbital angular momentum beams

    International Nuclear Information System (INIS)

    Li, Huanlu; Strain, Michael J.; Meriggi, Laura; Sorel, Marc; Chen, Lifeng; Zhu, Jiangbo; Cicek, Kenan; Wang, Jianwei; Thompson, Mark G.; Cai, Xinlun; Yu, Siyuan

    2015-01-01

    An integrated approach to thermal modulation of relative phase between two optical vortices with opposite chirality has been demonstrated on a silicon-on-insulator substrate. The device consists of a silicon-integrated optical vortex emitter and a phase controlled 3 dB coupler. The relative phase between two optical vortices can be actively modulated on chip by applying a voltage on the integrated heater. The phase shift is shown to be linearly proportional to applied electrical power, and the rotation angle of the interference pattern is observed to be inversely proportional to topological charge. This scheme can be used in lab-on-chip, communications and sensing applications. It can be intentionally implemented with other modulation elements to achieve more complicated applications

  9. High-Speed, Low-Power ADC for Digital Beam Forming (DBF) Systems, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — In Phase 1, Ridgetop Group designed a high-speed, yet low-power silicon germanium (SiGe)-based, analog-to-digital converter (ADC) to be a key element for digital...

  10. Pattern manipulation via on-chip phase modulation between orbital angular momentum beams

    Energy Technology Data Exchange (ETDEWEB)

    Li, Huanlu [Department of Electrical and Electronic Engineering, University of Bristol, University Walk, Bristol BS8 1TR (United Kingdom); School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LP (United Kingdom); Strain, Michael J. [School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LP (United Kingdom); Wolfson Centre, Institute of Photonics, University of Strathclyde, 106 Rottenrow East, Glasgow G4 0NW (United Kingdom); Meriggi, Laura; Sorel, Marc [School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LP (United Kingdom); Chen, Lifeng; Zhu, Jiangbo; Cicek, Kenan [Department of Electrical and Electronic Engineering, University of Bristol, University Walk, Bristol BS8 1TR (United Kingdom); Wang, Jianwei; Thompson, Mark G. [Centre for Quantum Photonics, H. H. Wills Physics Laboratory and Department of Electrical and Electronic Engineering, University of Bristol, Bristol BS8 1UB (United Kingdom); Cai, Xinlun, E-mail: caixlun5@mail.sysu.edu.cn [Centre for Quantum Photonics, H. H. Wills Physics Laboratory and Department of Electrical and Electronic Engineering, University of Bristol, Bristol BS8 1UB (United Kingdom); State Key Laboratory of Optoelectronic Materials and Technologies and School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Yu, Siyuan, E-mail: s.yu@bristol.ac.uk [Department of Electrical and Electronic Engineering, University of Bristol, University Walk, Bristol BS8 1TR (United Kingdom); State Key Laboratory of Optoelectronic Materials and Technologies and School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2015-08-03

    An integrated approach to thermal modulation of relative phase between two optical vortices with opposite chirality has been demonstrated on a silicon-on-insulator substrate. The device consists of a silicon-integrated optical vortex emitter and a phase controlled 3 dB coupler. The relative phase between two optical vortices can be actively modulated on chip by applying a voltage on the integrated heater. The phase shift is shown to be linearly proportional to applied electrical power, and the rotation angle of the interference pattern is observed to be inversely proportional to topological charge. This scheme can be used in lab-on-chip, communications and sensing applications. It can be intentionally implemented with other modulation elements to achieve more complicated applications.

  11. Generation of high-order Bessel vortex beam carrying orbital angular momentum using multilayer amplitude-phase-modulated surfaces in radiofrequency domain

    Science.gov (United States)

    Kou, Na; Yu, Shixing; Li, Long

    2017-01-01

    A high-order Bessel vortex beam carrying orbital angular momentum (OAM) is generated by using multilayer amplitude-phase-modulated surfaces (APMSs) at 10 GHz. The APMS transmitarray is composed of four-layer conformal square-loop (FCSL) surfaces with both amplitude and phase modulation. The APMS can transform a quasi-spherical wave emitted from the feeding source into a pseudo non-diffractive high-order Bessel vortex beam with OAM. The APMS for a second-order Bessel beam carrying OAM in the n = 2 mode is designed, fabricated, and measured. Full-wave simulation and measurement results confirm that Bessel vortex beams with OAM can be effectively generated using the proposed APMS transmitarray.

  12. Electron microscope phase enhancement

    Science.gov (United States)

    Jin, Jian; Glaeser, Robert M.

    2010-06-15

    A microfabricated electron phase shift element is used for modifying the phase characteristics of an electron beam passing though its center aperture, while not affecting the more divergent portion of an incident beam to selectively provide a ninety-degree phase shift to the unscattered beam in the back focal plan of the objective lens, in order to realize Zernike-type, in-focus phase contrast in an electron microscope. One application of the element is to increase the contrast of an electron microscope for viewing weakly scattering samples while in focus. Typical weakly scattering samples include biological samples such as macromolecules, or perhaps cells. Preliminary experimental images demonstrate that these devices do apply a ninety degree phase shift as expected. Electrostatic calculations have been used to determine that fringing fields in the region of the scattered electron beams will cause a negligible phase shift as long as the ratio of electrode length to the transverse feature-size aperture is about 5:1. Calculations are underway to determine the feasibility of aspect smaller aspect ratios of about 3:1 and about 2:1.

  13. Combined effect of dopant and electron beam-irradiation on phase transition in lithium potassium sulphate[Lithium potassium sulphate; Phase transition; Impurity effect; Thermal properties

    Energy Technology Data Exchange (ETDEWEB)

    Kassem, M.E.; Gaafar, M.; Abdel Gawad, M.M.H.; El-Muraikhi, M.; Ragab, I.M

    2004-02-01

    Thermodynamic studies of polycrystalline ruthenium (Ru) doped LiKSO{sub 4} have been made for different concentrations of Ru in the range 0%, 0.1%, 0.2%, 0.5%, 1%, 2%, 3% by weight. The thermal behaviour has been investigated using a differential scanning calorimeter in the vicinity of high temperature phases. From this, the effect of electron beam-irradiation on the thermal properties of these polycrystalline samples has been studied. The results showed a change in the transition temperature T{sub c}, as well as the value of specific heat C{sub P{sub max}} at the transition temperature due to the change in Ru content and irradiation energies. The change of enthalpy and entropy of the polycrystalline have been estimated numerically.

  14. WebPASS Explorer (HR Personnel Management)

    Data.gov (United States)

    US Agency for International Development — WebPass Explorer (WebPASS Framework): USAID is partnering with DoS in the implementation of their WebPass Post Personnel (PS) Module. WebPassPS does not replace...

  15. Cone-beam X-ray phase-contrast tomography for the observation of single cells in whole organs

    International Nuclear Information System (INIS)

    Krenkel, Martin

    2015-01-01

    X-ray imaging enables the nondestructive investigation of interior structures in otherwise opaque samples. In particular the use of computed tomography (CT) allows for arbitrary virtual slices through the object and 3D information about intricate structures can be obtained. However, when it comes to image very small structures like single cells, the classical CT approach is limited by the weak absorption of soft-tissue. The use of phase information, encoded in measureable intensity images by free-space propagation of coherent X-rays, allows a huge increase in contrast, which enables 3D reconstructions at higher resolutions. In this work the application of propagation-based phase-contrast tomography to lung tissue samples is demonstrated in close to in vivo conditions. Reconstructions of the lung structure of whole mice at down to 5 µm resolution are obtained at a selfbuilt CT setup, which is based on a liquid-metal jet X-ray source. To reach even higher resolutions, synchrotron radiation in combination with suitable holographic phase-retrieval algorithms is employed. Due to optimized cone-beam geometry, field of view and resolution can be varied over a wide range of parameters, so that information on different length scales can be achieved, covering several millimeters field of view down to a 3D resolution of 50 nm. Thus, the sub-cellular 3D imaging of single cells embedded in large pieces of tissue is enabled, which paves the way for future biomedical research.

  16. A new phase field model for material fatigue in an oscillating elastoplastic beam

    Czech Academy of Sciences Publication Activity Database

    Eleuteri, M.; Kopfová, J.; Krejčí, Pavel

    2015-01-01

    Roč. 35, č. 6 (2015), s. 2465-2495 ISSN 1078-0947 R&D Projects: GA ČR GAP201/10/2315 Institutional support: RVO:67985840 Keywords : hysteresis * fatigue * phase transition Subject RIV: BA - General Mathematics Impact factor: 1.127, year: 2015 http://www.aimsciences.org/journals/displayArticlesnew.jsp?paperID=10680

  17. Influence of the least-squares phase on optical vortices in strongly scintillated beams

    CSIR Research Space (South Africa)

    Chen, M

    2009-06-01

    Full Text Available , the average total number of vortices is reduced further. However, the reduction becomes smaller for each succes- sive step. This indicates that the ability of getting rid of optical vortices by removing the least-squares phase becomes progressively less...

  18. Characteristic of laser diode beam propagation through a collimating lens.

    Science.gov (United States)

    Xu, Qiang; Han, Yiping; Cui, Zhiwei

    2010-01-20

    A mathematical model of a laser diode beam propagating through a collimating lens is presented. Wave propagation beyond the paraxial approximation is studied. The phase delay of the laser diode wave in passing through the lens is analyzed in detail. The propagation optical field after the lens is obtained from the diffraction integral by the stationary phase method. The model is employed to predict the light intensity at various beam cross sections, and the computed intensity distributions are in a good agreement with the corresponding measurements.

  19. Single Pass Collider Memo: Gradient Perturbations of the SLC arc

    Energy Technology Data Exchange (ETDEWEB)

    Weng, W.T.; Sands, M.; /SLAC

    2016-12-16

    As the beam passes through the arcs, the gradient it encounters at each magnet differs from the design value. This deviation may be in part random and in part systematic. In this note we make estimates of the effects to be expected from both kinds of errors.

  20. Magnesium nitride phase formation by means of ion beam implantation technique

    International Nuclear Information System (INIS)

    Hoeche, Daniel; Blawert, Carsten; Cavellier, Matthieu; Busardo, Denis; Gloriant, Thierry

    2011-01-01

    Nitrogen implantation technique (Hardion + ) has been applied in order to modify the surface properties of magnesium and Mg-based alloys (AM50, AZ31). Nitrogen ions with an energy of approximately 100 keV were used to form the Mg 3 N 2 phase leading to improved surface properties. The samples were investigated using various characterization methods. Mechanical properties have been tested by means of nanoindention, the electrochemical behavior was measured by potentiodynamic polarization and impedance spectroscopy, phase formation by using grazing incidence Xray diffraction, the chemical state was determined by means of Xray induced photoelectron spectroscopy (XPS) and depth profiling by using secondary ions mass spectroscopy (SIMS). Additionally, the results were compared to calculated depth profiles using SRIM2008. The correlation of the results shows the nitride formation behavior to a depth of about 600 nm.

  1. Quasi-phase matching and quantum control of high harmonic generation in waveguides using counterpropagating beams

    Science.gov (United States)

    Zhang, Xiaoshi; Lytle, Amy L.; Cohen, Oren; Kapteyn, Henry C.; Murnane, Margaret M.

    2010-11-09

    All-optical quasi-phase matching (QPM) uses a train of counterpropagating pulses to enhance high-order harmonic generation (HHG) in a hollow waveguide. A pump pulse enters one end of the waveguide, and causes HHG in the waveguide. The counterpropagation pulses enter the other end of the waveguide and interact with the pump pulses to cause QPM within the waveguide, enhancing the HHG.

  2. Imaging RF Phased Array Receivers using Optically-Coherent Up-conversion for High Beam-Bandwidth Processing

    Science.gov (United States)

    2017-03-01

    It does so by using an optical lens to perform an inverse spatial Fourier Transform on the up-converted RF signals, thereby rendering a real-time... simultaneous beams or other engineered beam patterns. There are two general approaches to array-based beam forming: digital and analog. In digital beam...of significantly limiting the number of beams that can be formed simultaneously and narrowing the operational bandwidth. An alternate approach that

  3. Dipole saturated absorption modeling in gas phase: Dealing with a Gaussian beam

    Science.gov (United States)

    Dupré, Patrick

    2018-01-01

    With the advent of new accurate and sensitive spectrometers, cf. combining optical cavities (for absorption enhancement), the requirement for reliable molecular transition modeling is becoming more pressing. Unfortunately, there is no trivial approach which can provide a definitive formalism allowing us to solve the coupled systems of equations associated with nonlinear absorption. Here, we propose a general approach to deal with any spectral shape of the electromagnetic field interacting with a molecular species under saturation conditions. The development is specifically applied to Gaussian-shaped beams. To make the analytical expressions tractable, approximations are proposed. Finally, two or three numerical integrations are required for describing the Lamb-dip profile. The implemented model allows us to describe the saturated absorption under low pressure conditions where the broadening by the transit-time may dominate the collision rates. The model is applied to two specific overtone transitions of the molecular acetylene. The simulated line shapes are discussed versus the collision and the transit-time rates. The specific collisional and collision-free regimes are illustrated, while the Rabi frequency controls the intermediate regime. We illustrate how to recover the input parameters by fitting the simulated profiles.

  4. Phase I Development of Neutral Beam Injector Solid-State Power System

    Science.gov (United States)

    Prager, James; Ziemba, Timothy; Miller, Kenneth E.; Slobodov, Ilia; Anderson, Seth

    2017-10-01

    Neutral beam injection (NBI) is an important tool for plasma heating, current drive and a diagnostic at fusion science experiments around the United States, including tokamaks, validation platform experiments, and privately funded fusion concepts. Currently, there are no vendors in the United States for NBI power systems. Eagle Harbor Technologies (EHT), Inc. is developing a new power system for NBI that takes advantage of the latest developments in solid-state switching. EHT has developed a resonant converter that can be scaled to the power levels required for NBI at small-scale validation platform experiments like the Lithium Tokamak Experiment. This power system can be used to modulate the NBI voltages over the course of a plasma shot, which can lead to improved control over the plasma. EHT will present initial modeling used to design this system as well as experimental data showing operation at 15 kV and 40 A for 10 ms into a test load. With support of DOE SBIR.

  5. Quantum disentanglement and phase measurements

    International Nuclear Information System (INIS)

    Buzek, V.; Hillery, M.

    1995-01-01

    A 50:50 beam splitter disentangles a two-mode squeezed vacuum state into two single-mode squeezed vacuum states. With the proper choice of parameters these two single-mode states will be identical. If one is passed through a device which shifts its phase, then the phases of the shifted and reference (unshifted) modes can be determined by the Vogel-Schleich technique. In this way the phase difference, i.e. the phase shift, can be measured to an accuracy of 1/N, where N is the total number of photons coming into the beam splitter. An improved scheme is also proposed involving the disentanglement of a shifted two-mode squeezed vacuum state. This leads to two shifted squeezed vacuum states at the output of the beam splitter. If one of these is passed through the phase shifter, then by performing homodyne measurements on the shifted and unshifted modes the phase shift can again be determined to an accuracy of 1/N. (author) 4 figs., 14 refs

  6. Molecular beam epitaxy of GeTe-Sb2Te3 phase change materials studied by X-ray diffraction

    International Nuclear Information System (INIS)

    Shayduk, Roman

    2010-01-01

    The integration of phase change materials into semiconductor heterostructures may lead to the development of a new generation of high density non-volatile phase change memories. Epitaxial phase change materials allow to study the detailed structural changes during the phase transition and to determine the scaling limits of the memory. This work is dedicated to the epitaxial growth of Ge-Sb-Te phase change alloys on GaSb(001). We deposit Ge-Sb-Te (GST) films on GaSb(001) substrates by means of molecular beam epitaxy (MBE). The film orientation and lattice constant evolution is determined in real time during growth using grazing incidence X-ray diffraction (GID). The nucleation stage of the growth is studied in situ using reflection high energy electron diffraction (RHEED). Four growth regimes of GST on GaSb(001) were observed: amorphous, polycrystalline, incubated epitaxial and direct epitaxial. Amorphous film grows for substrate temperatures below 100 C. For substrate temperatures in the range 100-160 C, the film grows in polycrystalline form. Incubated epitaxial growth is observed at temperatures from 180 to 210 C. This growth regime is characterized by an initial 0.6nm thick amorphous layer formation, which crystallizes epitaxially as the film thickness increases. The determined lattice constant of the films is 6.01 A, very close to that of the metastable GST phase. The films predominantly possess an epitaxial cube-on-cube relationship. At higher temperatures the films grow epitaxially, however the growth rate is rapidly decreasing with temperature. At temperatures above 270 C the growth rate is zero. The composition of the grown films is close to 2:2:5 for Ge, Sb and Te, respectively. The determined crystal structure of the films is face centered cubic (FCC) with a rhombohedral distortion. The analysis of X-ray peak widths gives a value for the rhombohedral angle of 89.56 . We observe two types of reflections in reciprocal space indicating two FCC sublattices in

  7. Evidence of liquid phase during laser-induced periodic surface structures formation induced by accumulative ultraviolet picosecond laser beam

    Energy Technology Data Exchange (ETDEWEB)

    Huynh, T. T. D.; Petit, A.; Semmar, N., E-mail: nadjib.semmar@univ-orleans.fr [GREMI, UMR7344, CNRS/University of Orleans, 14 rue d' Issoudun, BP6744, 45067 Orleans Cedex 2 (France); Vayer, M. [ICMN, UMR 7374, CNRS/University of Orleans, 1b rue de la Ferollerie, CS 40059, 45071 Orleans Cedex (France); Sauldubois, A. [CME, UFR Sciences, University of Orleans, 1 Rue de Chartres, BP 6759, 45067 Orleans Cedex 2 (France)

    2015-11-09

    Laser-induced periodic surface structures (LIPSS) were formed on Cu/Si or Cu/glass thin films using Nd:YAG laser beam (40 ps, 10 Hz, and 30 mJ/cm{sup 2}). The study of ablation threshold is always achieved over melting when the variation of the number of pulses increases from 1 to 1000. But the incubation effect is leading to reduce the threshold of melting as increasing the number of laser pulse. Also, real time reflectivity signals exhibit typical behavior to stress the formation of a liquid phase during the laser-processing regime and helps to determine the threshold of soft ablation. Atomic Force Microscopy (AFM) analyses have shown the topology of the micro-crater containing regular spikes with different height. Transmission Electron Microscopy (TEM) allows finally to show three distinguished zones in the close region of isolated protrusions. The central zone is a typical crystallized area of few nanometers surrounded by a mixed poly-crystalline and amorphous area. Finally, in the region far from the protrusion zone, Cu film shows an amorphous structure. The real time reflectivity, AFM, and HR-TEM analyses evidence the formation of a liquid phase during the LIPSS formation in the picosecond regime.

  8. Non-linear temperature-dependent curvature of a phase change composite bimorph beam

    Science.gov (United States)

    Blonder, Greg

    2017-06-01

    Bimorph films curl in response to temperature. The degree of curvature typically varies in proportion to the difference in thermal expansion of the individual layers, and linearly with temperature. In many applications, such as controlling a thermostat, this gentle linear behavior is acceptable. In other cases, such as opening or closing a valve or latching a deployable column into place, an abrupt motion at a fixed temperature is preferred. To achieve this non-linear motion, we describe the fabrication and performance of a new bilayer structure we call a ‘phase change composite bimorph (PCBM)’. In a PCBM, one layer in the bimorph is a composite containing small inclusions of phase change materials. When the inclusions melt, their large (generally positive and  >1%) expansion coefficient induces a strong, reversible step function jump in bimorph curvature. The measured jump amplitude and thermal response is consistent with theory, and can be harnessed by a new class of actuators and sensors.

  9. Should positive phase III clinical trial data be required before proton beam therapy is more widely adopted? No

    International Nuclear Information System (INIS)

    Suit, Herman; Kooy, Hanne; Trofimov, Alexei; Farr, Jonathan; Munzenrider, John; DeLaney, Thomas; Loeffler, Jay; Clasie, Benjamin; Safai, Sairos; Paganetti, Harald

    2008-01-01

    Purpose: Evaluate the rationale for the proposals that prior to a wider use of proton radiation therapy there must be supporting data from phase III clinical trials. That is, would less dose to normal tissues be an advantage to the patient? Methods: Assess the basis for the assertion that proton dose distributions are superior to those of photons for most situations. Consider the requirements for determining the risks of normal tissue injury, acute and remote, in the examination of the data from a trial. Analyze the probable cost differential between high technology photon and proton therapy. Evaluate the rationale for phase III clinical trials of proton vs photon radiation therapy when the only difference in dose delivered is a difference in distribution of low LET radiation. Results: The distributions of biological effective dose by protons are superior to those by X-rays for most clinical situations, viz. for a defined dose and dose distribution to the target by protons there is a lower dose to non-target tissues. This superiority is due to these physical properties of protons: (1) protons have a finite range and that range is exclusively dependent on the initial energy and the density distribution along the beam path; (2) the Bragg peak; (3) the proton energy distribution may be designed to provide a spread out Bragg peak that yields a uniform dose across the target volume and virtually zero dose deep to the target. Importantly, proton and photon treatment plans can employ beams in the same number and directions (coplanar, non-co-planar), utilize intensity modulation and employ 4D image guided techniques. Thus, the only difference between protons and photons is the distribution of biologically effective dose and this difference can be readily evaluated and quantified. Additionally, this dose distribution advantage should increase the tolerance of certain chemotherapeutic agents and thus permit higher drug doses. The cost of service (not developmental) proton

  10. Novel corrosion experiments using the wire beam electrode: (III) Measuring electrochemical corrosion parameters from both the metallic and electrolytic phases

    International Nuclear Information System (INIS)

    Tan, Yong-Jun; Liu, Tie; Aung, Naing Naing

    2006-01-01

    The wire beam electrode (WBE) and the scanning reference electrode technique (SRET) have been applied in a novel combination to measure, for the first time, electrochemical parameters simultaneously from both the metallic and electrolytic phases of a corroding metal surface. The objective of this work is to demonstrate the application of this combined WBE-SRET method in obtaining unique information on localised corrosion mechanism, by investigating typical corrosion processes occurring over a mild steel WBE surface exposed to the classic Evans solution. The WBE method was used to map current and potential distributions in the metallic phase, and the SRET was used to map current or potential distribution in the electrolytic phase. It has been found that the combined WBE-SRET method is able to gain useful information on macro-cell electrochemical corrosion processes that involve macro-scale separation of anodes and cathodes. In such macro-cell corrosion systems, maps measured using WBE and SRET were found to correlate with each other and both methods were able to detect the locations of anodic sites. However the movement of the scanning probe during SRET measurements was found to affect the SRET detection of cathodic sites. In micro-cell corrosion systems where the separation of anodic and cathodic sites were less distinct, SRET measurement was found to be insensitive in detecting anodic and cathodic sites, while the WBE method was still able to produce results that correlated well with observed corrosion behaviour. Results obtained from this work suggest that the WBE-SRET method is applicable for understanding the initiation, propagation and electrochemical behaviour of localised corrosion anodes and cathodes, and also their dependence on externally controllable variables, such as solution pH changes and the existence of surface coatings

  11. Ionization beam scanner

    CERN Multimedia

    CERN PhotoLab

    1973-01-01

    Inner structure of an ionization beam scanner, a rather intricate piece of apparatus which permits one to measure the density distribution of the proton beam passing through it. On the outside of the tank wall there is the coil for the longitudinal magnetic field, on the inside, one can see the arrangement of electrodes creating a highly homogeneous transverse electric field.

  12. About the influence of phase mixing process and current neutralization on the resistive sausage instability dynamics of a relativistic electron beam

    Science.gov (United States)

    Kolesnikov, E. K.; Manuilov, A. S.; Petrov, V. S.; Zelensky, A. G.

    2018-05-01

    The resistive sausage instability of the relativistic electron beam in dense gas-plasma medium in the case of the generation of equilibrium return plasma current is investigated. In this situation the eigenvalue equation of this instability is obtained. The stabilizing and destabilizing effects of the phase mixing and generation of the return plasma current respectively have been shown.

  13. The transmission theory of electrostatic analyzer in six dimensional phase space and the concept design of a supersensitive mass spectrometer beam line for HI-13 tandem accelerator

    International Nuclear Information System (INIS)

    Guan Xialing; Cao Qingxi; Zhang Jie; Ye Jingping

    1986-01-01

    It follows from the motion equations of charged particle in curvilinear coordinates system that the transfer matrix of electrostatic analyzer was derived in six dimensional phase space. In accordance with these matrixes, the concept design of the supersensitive mass spectrometer beam line for HI-13 tandem accelerator was calculated

  14. Blind sensor calibration using approximate message passing

    International Nuclear Information System (INIS)

    Schülke, Christophe; Caltagirone, Francesco; Zdeborová, Lenka

    2015-01-01

    The ubiquity of approximately sparse data has led a variety of communities to take great interest in compressed sensing algorithms. Although these are very successful and well understood for linear measurements with additive noise, applying them to real data can be problematic if imperfect sensing devices introduce deviations from this ideal signal acquisition process, caused by sensor decalibration or failure. We propose a message passing algorithm called calibration approximate message passing (Cal-AMP) that can treat a variety of such sensor-induced imperfections. In addition to deriving the general form of the algorithm, we numerically investigate two particular settings. In the first, a fraction of the sensors is faulty, giving readings unrelated to the signal. In the second, sensors are decalibrated and each one introduces a different multiplicative gain to the measurements. Cal-AMP shares the scalability of approximate message passing, allowing us to treat large sized instances of these problems, and experimentally exhibits a phase transition between domains of success and failure. (paper)

  15. Common pass decentered annular ring resonator

    Energy Technology Data Exchange (ETDEWEB)

    Holmes, D. A.; Waite, T. R.

    1985-04-30

    An optical resonator having an annular cylindrical gain region for use in a chemical laser or the like in which two ring-shaped mirrors having substantially conical reflecting surfaces are spaced apart along a common axis of revolution of the respective conical surfaces. A central conical mirror reflects incident light directed along said axis radially outwardly to the reflecting surface of a first one of the ring-shaped mirrors. The radial light rays are reflected by the first ring mirror to the second ring mirror within an annular cylindrical volume concentric with said common axis and forming a gain region. Light rays impinging on the second ring mirror are reflected to diametrically opposite points on the same conical mirror surfaces and back to the first ring mirror through the same annular cylindrical volume. The return rays are then reflected by the conical mirror surface of the first ring mirror back to the central conical mirror. The mirror surfaces are angled such that the return rays are reflected back along the common axis by the central mirror in a concentric annular cylindrical volume. A scraper mirror having a central opening centered on said axis and an offset opening reflects all but the rays passing through the two openings in an output beam. The rays passing through the second opening are reflected back through the first opening to provide feedback.

  16. Beam-Beam Effects

    International Nuclear Information System (INIS)

    Herr, W; Pieloni, T

    2014-01-01

    One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities

  17. High-energy ion-beam-induced phase separation in SiOx films

    International Nuclear Information System (INIS)

    Arnoldbik, W.M.; Tomozeiu, N.; Hattum, E.D. van; Lof, R.W.; Vredenberg, A.M.; Habraken, F.H.P.M.

    2005-01-01

    The modification of the nanostructure of silicon suboxide (SiO x ) films as a result of high-energy heavy-ion irradiation has been studied for the entire range 0.1≤x x films have been obtained by radio-frequency magnetron sputter deposition. For 50 MeV 63 Cu 8+ ions and an angle of incidence of 20 deg. with the plane of the surface, and for x≥0.5, it takes a fluence of about 10 14 /cm 2 to reach a Si-O-Si infrared absorption spectrum, which is supposed to be characteristic for a Si-SiO 2 composite film structure. For smaller x values, it takes a much larger fluence. The interpretation of the IR spectra is corroborated for the surface region by results from x-ray photoelectron spectroscopy. The results present evidence for a mechanism, in which the phase separation takes place in the thermal spike, initiated by the energy deposited in many overlapping independent ion tracks. Such a process is possible since the suboxides fulfill the conditions for spinodal decomposition

  18. Safe LHC beam commissioning

    International Nuclear Information System (INIS)

    Uythoven, J.; Schmidt, R.

    2007-01-01

    Due to the large amount of energy stored in magnets and beams, safety operation of the LHC is essential. The commissioning of the LHC machine protection system will be an integral part of the general LHC commissioning program. A brief overview of the LHC Machine Protection System will be given, identifying the main components: the Beam Interlock System, the Beam Dumping System, the Collimation System, the Beam Loss Monitoring System and the Quench Protection System. An outline is given of the commissioning strategy of these systems during the different commissioning phases of the LHC: without beam, injection and the different phases with stored beam depending on beam intensity and energy. (author)

  19. Neutral beam monitoring

    International Nuclear Information System (INIS)

    Fink, J.H.

    1979-01-01

    A neutral beam generated by passing accelerated ions through a walled cell containing a low energy neutral gas, such that charge exchange partially neutralizes the high energy beam, is monitored by detecting the current flowing through the cell wall produced by low energy ions which drift to the wall after the charge exchange. By segmenting the wall into radial and longitudinal segments various beam conditions are identified. (U.K.)

  20. Lifetime improvement and beam stabilization by longitudinal phase modulation at the DELTA electron storage ring; Lebensdauerverbesserung und Strahlstabilisierung durch longitudinale Phasenmodulation am Elektronenspreicherring DELTA

    Energy Technology Data Exchange (ETDEWEB)

    Fuersch, Jonathan

    2014-10-16

    In DELTA especially at high beam currents often the occurence of an instability of a longitudinal oscillation mode is observed. In the framework of the present thesis first with different procedure the cause of the longitudinal oscillation mode, which is especially strongly excited at high beam currents, is searched for. Thereby connections between the occurrence of this mode and parameters from the region of the storage-ring high-frequency system is observed. It is shown by comparison of different procedures, simulation calculations, and experimental pre-examinations, that especially by a phase modulation of the storage-ring high frequency an essential improvement of especially the longitudinal beam stability and the beam lifetime can be reached. For the durable and reliable improvement of these beam properties in the framework of the present thesis a system for the longitudinal phase modulation of the after-acceleration voltage in the cavity resonator of the DELTA storage ring is concipated, developed, constructed, taken in operation, and tested. Finally the results aimed hereby are presented and discussed.

  1. North Texas Sediment Budget: Sabine Pass to San Luis Pass

    Science.gov (United States)

    2006-09-01

    concrete units have been placed over sand-filled fabric tube . .......................................33 Figure 28. Sand-filled fabric tubes protecting...system UTM Zone 15, NAD 83 Longshore drift directions King (in preparation) Based on wave hindcast statistics and limited buoy data Rollover Pass...along with descriptions of the jetties and limited geographic coordinate data1 (Figure 18). The original velum or Mylar sheets from which the report

  2. Estimates for the probability of survival of electrons in passing through a radiator

    International Nuclear Information System (INIS)

    Loos, J.

    1977-01-01

    Some calculations on the survival of electrons passing through various radiator thicknesses are tabulated. The results of these calculations should serve as a guide for expected attenuation of electrons in the beam when various Pb radiators are inserted

  3. Phase 1 Study of Dose Escalation in Hypofractionated Proton Beam Therapy for Non-Small Cell Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Daniel R., E-mail: dgomez@mdanderson.org [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Gillin, Michael [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Liao, Zhongxing [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Wei, Caimiao [Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Lin, Steven H.; Swanick, Cameron; Alvarado, Tina; Komaki, Ritsuko; Cox, James D.; Chang, Joe Y. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

    2013-07-15

    Background: Many patients with locally advanced non-small cell lung cancer (NSCLC) cannot undergo concurrent chemotherapy because of comorbidities or poor performance status. Hypofractionated radiation regimens, if tolerable, may provide an option to these patients for effective local control. Methods and Materials: Twenty-five patients were enrolled in a phase 1 dose-escalation trial of proton beam therapy (PBT) from September 2010 through July 2012. Eligible patients had histologically documented lung cancer, thymic tumors, carcinoid tumors, or metastatic thyroid tumors. Concurrent chemotherapy was not allowed, but concurrent treatment with biologic agents was. The dose-escalation schema comprised 15 fractions of 3 Gy(relative biological effectiveness [RBE])/fraction, 3.5 Gy(RBE)/fraction, or 4 Gy(RBE)/fraction. Dose constraints were derived from biologically equivalent doses of standard fractionated treatment. Results: The median follow-up time for patients alive at the time of analysis was 13 months (range, 8-28 months). Fifteen patients received treatment to hilar or mediastinal lymph nodes. Two patients experienced dose-limiting toxicity possibly related to treatment; 1 received 3.5-Gy(RBE) fractions and experienced an in-field tracheoesophageal fistula 9 months after PBT and 1 month after bevacizumab. The other patient received 4-Gy(RBE) fractions and was hospitalized for bacterial pneumonia/radiation pneumonitis 4 months after PBT. Conclusion: Hypofractionated PBT to the thorax delivered over 3 weeks was well tolerated even with significant doses to the lungs and mediastinal structures. Phase 2/3 trials are needed to compare the efficacy of this technique with standard treatment for locally advanced NSCLC.

  4. Single-pass BPM system of the Photon Factory storage ring.

    Science.gov (United States)

    Honda, T; Katoh, M; Mitsuhashi, T; Ueda, A; Tadano, M; Kobayashi, Y

    1998-05-01

    At the 2.5 GeV ring of the Photon Factory, a single-pass beam-position monitor (BPM) system is being prepared for the storage ring and the beam transport line. In the storage ring, the injected beam position during the first several turns can be measured with a single injection pulse. The BPM system has an adequate performance, useful for the commissioning of the new low-emittance lattice. Several stripline BPMs are being installed in the beam transport line. The continuous monitoring of the orbit in the beam transport line will be useful for the stabilization of the injection energy as well as the injection beam orbit.

  5. Phase II Radiation therapy oncology group trial of weekly paclitaxel and conventional external beam radiation therapy for supratentorial glioblastoma multiforme

    International Nuclear Information System (INIS)

    Langer, Corey J.; Ruffer, James; Rhodes, Harker; Paulus, Rebecca; Murray, Kevin; Movsas, Benjamin; Curran, Walter

    2001-01-01

    Purpose: Fractionated external beam radiotherapy (EBRT) ± carmustine (BCNU) is the standard of care for patients with glioblastoma multiforme (GBM), but survival results remain poor. Preclinical studies indicate synergy between RT and paclitaxel (TAX) in astrocytoma cell lines. Phase I studies in GBM have demonstrated a maximum tolerated dose for TAX of 225 mg/m 2 /3 h/week x 6, during EBRT, with no exacerbation of typical RT-induced toxicities. The Radiation Therapy Oncology Group (RTOG) therefore mounted a Phase II study to determine the feasibility and efficacy of conventional EBRT and concurrent weekly TAX at its MTD. Patients and Methods: Sixty-two patients with histologic diagnosis of GBM were enrolled from 8/16/96 through 3/21/97 in a multi-institutional Phase II trial of EBRT and TAX 225 mg/m 2 /3 h (1-3 h before EBRT), administered the first treatment day of each RT week. Total EBRT dose was 60 Gy (200 cGy/fraction), 5 days per week. A smaller treatment field, to include gross disease plus a margin only, was used after 46 Gy. Results: Sixty-one patients (98%) were evaluable. Median age was 55 years (range, 28-78). Seventy-four percent were ≥50 years. Recursive partitioning analysis (RPA) Classes III, IV, V, VI included 10 (17%), 21 (34%), 25 (41%), and 5 (8%) patients, respectively. Gross total resection was performed in only 16%. There was no Grade 3 or 4 neutropenia or thrombocytopenia. Hypersensitivity reactions precluding further use of TAX occurred in 4 patients. There were 2 instances of late neurotoxicity (4% Grade 3 or 4). Ninety-one percent of patients received treatment per protocol. Seventy-seven percent completed prescribed treatment (6 weeks). Of 35 patients with measurable disease, CR/PR was observed in 23%, MR in 17%, and SD in 43%. Seventeen percent demonstrated progression at first follow-up. Median potential follow-up time is 20 months. Median survival is 9.7 months, with median survivals for RPA classes III, IV, V, and VI of 16.3, 10

  6. Life cycle assessment based environmental impact estimation model for pre-stressed concrete beam bridge in the early design phase

    International Nuclear Information System (INIS)

    Kim, Kyong Ju; Yun, Won Gun; Cho, Namho; Ha, Jikwang

    2017-01-01

    The late rise in global concern for environmental issues such as global warming and air pollution is accentuating the need for environmental assessments in the construction industry. Promptly evaluating the environmental loads of the various design alternatives during the early stages of a construction project and adopting the most environmentally sustainable candidate is therefore of large importance. Yet, research on the early evaluation of a construction project's environmental load in order to aid the decision making process is hitherto lacking. In light of this dilemma, this study proposes a model for estimating the environmental load by employing only the most basic information accessible during the early design phases of a project for the pre-stressed concrete (PSC) beam bridge, the most common bridge structure. Firstly, a life cycle assessment (LCA) was conducted on the data from 99 bridges by integrating the bills of quantities (BOQ) with a life cycle inventory (LCI) database. The processed data was then utilized to construct a case based reasoning (CBR) model for estimating the environmental load. The accuracy of the estimation model was then validated using five test cases; the model's mean absolute error rates (MAER) for the total environmental load was calculated as 7.09%. Such test results were shown to be superior compared to those obtained from a multiple-regression based model and a slab area base-unit analysis model. Henceforth application of this model during the early stages of a project is expected to highly complement environmentally friendly designs and construction by facilitating the swift evaluation of the environmental load from multiple standpoints. - Highlights: • This study is to develop the model of assessing the environmental impacts on LCA. • Bills of quantity from completed designs of PSC Beam were linked with the LCI DB. • Previous cases were used to estimate the environmental load of new case by CBR model. • CBR

  7. Life cycle assessment based environmental impact estimation model for pre-stressed concrete beam bridge in the early design phase

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyong Ju, E-mail: kjkim@cau.ac.kr; Yun, Won Gun, E-mail: ogun78@naver.com; Cho, Namho, E-mail: nhc51@cau.ac.kr; Ha, Jikwang, E-mail: wlrhkd29@gmail.com

    2017-05-15

    The late rise in global concern for environmental issues such as global warming and air pollution is accentuating the need for environmental assessments in the construction industry. Promptly evaluating the environmental loads of the various design alternatives during the early stages of a construction project and adopting the most environmentally sustainable candidate is therefore of large importance. Yet, research on the early evaluation of a construction project's environmental load in order to aid the decision making process is hitherto lacking. In light of this dilemma, this study proposes a model for estimating the environmental load by employing only the most basic information accessible during the early design phases of a project for the pre-stressed concrete (PSC) beam bridge, the most common bridge structure. Firstly, a life cycle assessment (LCA) was conducted on the data from 99 bridges by integrating the bills of quantities (BOQ) with a life cycle inventory (LCI) database. The processed data was then utilized to construct a case based reasoning (CBR) model for estimating the environmental load. The accuracy of the estimation model was then validated using five test cases; the model's mean absolute error rates (MAER) for the total environmental load was calculated as 7.09%. Such test results were shown to be superior compared to those obtained from a multiple-regression based model and a slab area base-unit analysis model. Henceforth application of this model during the early stages of a project is expected to highly complement environmentally friendly designs and construction by facilitating the swift evaluation of the environmental load from multiple standpoints. - Highlights: • This study is to develop the model of assessing the environmental impacts on LCA. • Bills of quantity from completed designs of PSC Beam were linked with the LCI DB. • Previous cases were used to estimate the environmental load of new case by CBR model. • CBR

  8. The ATLAS beam pick-up based timing system

    International Nuclear Information System (INIS)

    Ohm, C.; Pauly, T.

    2010-01-01

    The ATLAS BPTX stations are composed of electrostatic button pick-up detectors, located 175 m away along the beam pipe on both sides of ATLAS. The pick-ups are installed as a part of the LHC beam instrumentation and used by ATLAS for timing purposes. The usage of the BPTX signals in ATLAS is twofold: they are used both in the trigger system and for LHC beam monitoring. The BPTX signals are discriminated with a constant-fraction discriminator to provide a Level-1 trigger when a bunch passes through ATLAS. Furthermore, the BPTX detectors are used by a stand-alone monitoring system for the LHC bunches and timing signals. The BPTX monitoring system measures the phase between collisions and clock with a precision better than 100 ps in order to guarantee a stable phase relationship for optimal signal sampling in the sub-detector front-end electronics. In addition to monitoring this phase, the properties of the individual bunches are measured and the structure of the beams is determined. On September 10, 2008, the first LHC beams reached the ATLAS experiment. During this period with beam, the ATLAS BPTX system was used extensively to time in the read-out of the sub-detectors. In this paper, we present the performance of the BPTX system and its measurements of the first LHC beams.

  9. Ion beam diagnosis

    International Nuclear Information System (INIS)

    Strehl, P.

    1994-04-01

    This report is an introduction to ion beam diagnosis. After a short description of the most important ion beam parameters measurements of the beam current by means of Faraday cups, calorimetry, and beam current transformers and measurements of the beam profile by means of viewing screens, profile grids and scanning devices, and residual gas ionization monitors are described. Finally measurements in the transverse and longitudinal phase space are considered. (HSI)

  10. Time-resolved electron beam phase space tomography at a soft x-ray free-electron laser

    Directory of Open Access Journals (Sweden)

    Michael Röhrs

    2009-05-01

    Full Text Available High-gain free-electron lasers (FELs in the ultraviolet and x-ray regime put stringent demands on the peak current, transverse emittance, and energy spread of the driving electron beam. At the soft x-ray FEL FLASH, a transverse deflecting microwave structure (TDS has been installed to determine these parameters for the longitudinally compressed bunches, which are characterized by a narrow leading peak of high charge density and a long tail. The rapidly varying electromagnetic field in the TDS deflects the electrons vertically and transforms the time profile into a streak on an observation screen. The bunch current profile was measured single shot with an unprecedented resolution of 27 fs under FEL operating conditions. A precise single-shot measurement of the energy distribution along a bunch was accomplished by using the TDS in combination with an energy spectrometer. Variation of quadrupole strengths allowed for a determination of the horizontal emittance as a function of the longitudinal position within a bunch, the so-called slice emittance. In the bunch tail, a normalized slice emittance of about 2  μm was found, in agreement with expectations. In the leading spike, however, surprisingly large emittance values were observed, in apparent contradiction with the low emittance deduced from the measured FEL gain. By applying three-dimensional phase space tomography, we were able to show that the bunch head contains a central core of low emittance and high local current density, which is presumably the lasing part of the bunch.

  11. Connecticut church passes genetics resolution.

    Science.gov (United States)

    Culliton, B J

    1984-11-09

    The Connecticut Conference of the United Church of Christ, which represents the largest Protestant denomination in the state, has passed a resolution affirming an ethical duty to do research on human gene therapy and is planning to form local church groups to study the scientific and ethical issues involved. The resolution is intended to counter an earlier one proposed by Jeremy Rifkin to ban all efforts at engineering specific traits into the human germline. The Rifkin proposal had been endorsed by a large number of religious leaders, including the head of the U.S. United Church of Christ, but was subsequently characterized by many of the church leaders as overly restrictive.

  12. Multi-bunch energy spread induced by beam loading in standing wave structure

    International Nuclear Information System (INIS)

    Ferrario, M.; Tazzioli, F.

    1995-04-01

    The interaction of a relativistic beam with the modes of the TM 010 pass-band of a multicell cavity does not cause any problem: although all the modes are excited by the RF (radiofrequency) generator, resulting in different cell excitations during the cavity filling and the beam pulse, the net accelerating field exhibits negligible fluctuations from bunch to bunch. However, when the beam is not fully relativistic, this is no more true. The phase slippage occurring in the first cells, between the non relativistic beam and the lower pass-band modes, produces an effective enhancement of the shunt impedances, which is usually negligible for a relativistic beam in a well tuned cavity. Moreover, the voltage jumps (amplitude and phase) occurring at each bunch passage, as well as the beam detuning caused by the off-crest bunches, vary from cell to cell. These effects enhance dramatically the fluctuation of the accelerating voltage, with a dominant beating provided by the pass-band mode nearest to the pi-mode. The induced beam energy spread has been estimated by the help of two distinct codes, developed at Frascati (Italy) and (Saclay), with results in good agreement. While an interaction integral is computed at each bunch passage, the cavity refilling is calculated by solving coupled differential equations of the modes of the pass-band, driven by a generator linked to one end-cell. It is shown also that the intermode coupling arises from the external Q of the drive end-cell, and not from the wall losses. For illustration, the authors applied the method to the beam-loading problem in the SC capture cavity of the low charge injector of the TESLA test facility installed at DESY

  13. Gas-phase mechanisms in the growth of ZrCyN1-y thin films by pulsed reactive crossed-beam laser ablation

    International Nuclear Information System (INIS)

    Spillmann, H.; Clerc, C.; Doebeli, M.; Willmott, P.R.

    2002-01-01

    Superhard zirconium carbonitride films have been grown via pulsed reactive crossed-beam laser ablation (PRCLA) using zirconium metal and a nitrogen- and carbon-containing gas pulse mixture. The control of stoichiometry was much simplified by using the thermally stable gas-phase species N 2 and CH 4 . The gas-phase processes are investigated using quadrupole mass spectroscopy and optical emission spectroscopy. The excitation of the ablation plume depends intimately on the collision partner of the gas pulse, in particular on its density of states and the probability of energy transfer to internal degrees of freedom

  14. Development of beam instruments at JAERI cyclotron facility

    Energy Technology Data Exchange (ETDEWEB)

    Okumura, Susumu; Fukuda, Mitsuhiro; Ishibori, Ikuo; Agematsu, Takashi; Yokota, Watalu; Nara, Takayuki; Nakamura, Yoshiteru; Arakawa, Kazuo [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1997-03-01

    A beam phase monitor and two kinds of fluence distribution monitors have been developed for measuring characteristics of cyclotron beams. The beam phase monitor provides a beam phase signal for tuning a beam chopping system and a beam phase selection system. A two-dimensional fluence distribution on a large area is measured with fluence distribution monitors. (author)

  15. Theory of longitudinal atomic beam spin echo and parity violating Berry-phases in atoms; Theorie des longitudinalen Atomstrahl-Spinechos und paritaetsverletzende Berry-Phasen in Atomen

    Energy Technology Data Exchange (ETDEWEB)

    Bergmann, T.F.

    2006-07-19

    We present a nonrelativistic theory for the quantum mechanical description of longitudinal atomic beam spin echo experiments, where a beam of neutral atoms is subjected to static electric and magnetic fields. The atomic wave function is the solution of a matrix-valued Schroedinger equation and can be written as superposition of local (atomic) eigenstates of the potential matrix. The position- and time-dependent amplitude function of each eigenstate represents an atomic wave packet and can be calculated in a series expansion with a master formula that we derive. The zeroth order of this series expansion describes the adiabatic limit, whereas the higher order contributions contain the mixing of the eigenstates and the corresponding amplitude functions. We give a tutorial for the theoretical description of longitudinal atomic beam spin echo experiments and for the so-called Fahrplan model, which is a visualisation tool for the propagation of wave packets of different atomic eigenstates. As an example for the application of our theory, we study parity violating geometric (Berry-)phases. In this context, we define geometric flux densities, which for certain field configurations can be used to illustrate geometric phases in a vector diagram. Considering an example with a specific field configuration, we prove the existence of a parity violating geometric phase. (orig.)

  16. A sweep plate emittance scanner for high-power CW ion beams

    International Nuclear Information System (INIS)

    Debiak, T.W.; Ng, Y.; Sredniawski, J.; Stasi, W.

    1996-01-01

    Sweep plate scanners are preferred for emittance measurement due to their versatility, simplicity, and precision. At the Advanced Technology and Development Center of Northrop Grumman, we have routinely used these devices for characterization of injector beams with less than 20 W/cm 2 average power density. To characterize higher power beams, like those required for production of tritium or for radioactive waste transmutation, the scanner pod and data collection algorithm must be redesigned due to the possibility of melting the scanner's protective front face or distorting the precision entrance knife edges. Among the methods we have used to mitigate these effects, one consists of drastically reducing the amount of time required for data collection. In this method, the emittance scanner pod traverses the beam in two passes, each requiring less than 0.5 second. In the first pass, the phase space limits of the beam are determined. In the second pass, data is collected primarily within the phase space region limits determined in the first pass. In this way, enough points are collected to assure that the precision of the measurement is high, even though the data collection time for each scan is less than 0.5 second. This paper will describe the layout of the scanner components, the data collection electronics and algorithm, and the data analysis. (author)

  17. Phase and amplitude stability of a pulsed RF system on the example of the CLIC drive beam LINAC

    CERN Document Server

    AUTHOR|(CDS)2132320; Prof. BANTEL, Michael

    The CLIC drive beam accelerator consists of the Drive Beam Injector (DBI) and two Drive Beam Linacs (DBLs). The drive beam injector is composed of a thermionic electron source, 3 Sub Harmonic Bunchers (SHBs), a pre-buncher, and several acceleration structures. In the electron source the DC electron beam is produced from a thermionic cathode. The following buncher cavities group ("bunch") the electrons to be accelerated by RF later on. Each electron bunch has an energy of 140 keV, a length of 3 mm, and a charge qb = 8.4 nC. Afterwards the electrons are accelerated in the 1 GHz accelerating structures up to 50MeV. The pulsed Radio Frequency (RF) power for this acceleration is provided by 1 GHz, 20MW modulator-klystron units, one per acceleration structure. A klystron is an RF amplifier based on a linear-beam vacuum tube. The high voltage modulator supplies the acceleration voltage to this tube. A DC electron beam gets modulated with an input signal, the modulation enhances in a drift space, and finally the powe...

  18. Emittance scanner for intense low-energy ion beams

    International Nuclear Information System (INIS)

    Allison, P.W.; Sherman, J.D.; Holtkamp, D.B.

    1983-01-01

    An emittance scanner has been developed for use with low-energy H - ion beams to satisfy the following requirements: (1) angular resolution of +-1/2 mrad, (2) small errors from beam space charge, and (3) compact and simple design. The scanner consists of a 10-cm-long analyzer containing two slits and a pair of electric deflection plates driven by a +-500-V linear ramp generator. As the analyzer is mechanically driven across the beam, the front slit passes a thin ribbon of beam through the plates. The ion transit time is short compared with the ramp speed; therefore, the initial angle of the ions that pass through the rear slit is proportional to the instantaneous ramp voltage. The current through the rear slit then is proportional to the phase-space density d 2 i/dxdx'. The data are computer-analyzed to give, for example, rms emittance and phase-space density contours. Comparison of measured data with those calculated from a prepared (collimated) phase space is in good agreement

  19. The Swedish Blood Pass project.

    Science.gov (United States)

    Berglund, B; Ekblom, B; Ekblom, E; Berglund, L; Kallner, A; Reinebo, P; Lindeberg, S

    2007-06-01

    Manipulation of the blood's oxygen carrying capacity (CaO(2)) through reinfusion of red blood cells, injections of recombinant erythropoietin or by other means results in an increased maximal oxygen uptake and concomitantly enhanced endurance performance. Therefore, there is a need to establish a system--"A Blood Pass"--through which such illegal and unethical methods can be detected. Venous blood samples were taken under standardized conditions from 47 male and female Swedish national and international elite endurance athletes four times during the athletic year of the individual sport (beginning and end of the preparation period and at the beginning and during peak performance in the competition period). In these samples, different hematological values were determined. ON(hes) and OFF(hre) values were calculated according to the formula of Gore et al. A questionnaire regarding training at altitude, alcohol use and other important factors for hematological status was answered by the athletes. There were some individual variations comparing hematological values obtained at different times of the athletic year or at the same time in the athletic year but in different years. However, the median values of all individual hematological, ON(hes) and OFF(hre), values taken at the beginning and the end of the preparation or at the beginning and the end of the competition period, respectively, as well as median values for the preparation and competition periods in the respective sport, were all within the 95% confidence limit (CI) of each comparison. It must be mentioned that there was no gender difference in this respect. This study shows that even if there are some individual variations in different hematological values between different sampling times in the athletic year, median values of important hematological factors are stable over time. It must be emphasized that for each blood sample, the 95% CI in each athlete will be increasingly narrower. The conclusion is that

  20. The PASS project architectural model

    International Nuclear Information System (INIS)

    Day, C.T.; Loken, S.; Macfarlane, J.F.

    1994-01-01

    The PASS project has as its goal the implementation of solutions to the foreseen data access problems of the next generation of scientific experiments. The architectural model results from an evaluation of the operational and technical requirements and is described in terms of an abstract reference model, an implementation model and a discussion of some design aspects. The abstract reference model describes a system that matches the requirements in terms of its components and the mechanisms by which they communicate, but does not discuss policy or design issues that would be necessary to match the model to an actual implementation. Some of these issues are discussed, but more detailed design and simulation work will be necessary before choices can be made

  1. The interaction between a beam and a superconducting cavity module: Measurements in CESR and CESR-Phase 3 goals

    Energy Technology Data Exchange (ETDEWEB)

    Belomestnykh, S; Flynn, G; Hartung, W; Kirchgessner, J; Moffat, D; Muller, H; Padamsee, H; Pisharody, M; Veshcherevich, V [Cornell Univ., Ithaca, NY (United States). Lab. of Nuclear Studies

    1996-08-01

    Plans for the next generation of electron-positron colliders (B-factories and B-factory-like machines) call for high beam currents to produce luminosities of the order of 10 (exp 33). To store these high currents in a machine, special attention must be paied to the interaction of the beam with discontinuities in the surrounding vacuum chamber. RF cavities are among the biggest perturbations in accelerator vacuum chambers and are therefore among the biggest sources of beam instabilities. Accelerating structures of new machines are being designed to have smaller impedance to reduce the beam-cavity interaction. Prototypes for the cavity, input coupler, cryostat, and higher-order mode (HOM) loads were subjected and are tested in CESR. A superconducting (SRF) cavity was installed in addition to the four five-cell normal conducting cavities. As a result, the calorimetry and RF power results agree with predictions up to their respective uncertainties. The results of wake potential sampling suggested that the wake fields of the SRF cavity will not limit the performance of CESR in bunch train operation. No beam instabilities or dangerous HOMs were encountered while sweeping the HOM frequencies using the cavity tuner or while exciting multipole HOMs by displacing the beam off axis. (G.K.)

  2. WebPASS ICASS (HR Personnel Management)

    Data.gov (United States)

    US Agency for International Development — WebPASS Joint Administrative Support Platforms Post Administrative Software Suite - U.S. Department of State Executive Officers application suite. Web.PASS is the...

  3. LHC First Beam 2008

    CERN Multimedia

    Tuura, L

    2008-01-01

    The CMS Centre played a major part in the LHC First Beam Event on September 10th 2008: it was a central point for CMS, hosting journalists from all over the world and providing live link-ups to collaborating institutes as well as, of course, monitoring events as they happened at Point 5. It was also a venue for celebration as the beam completed circuits of the LHC in both directions, passing successfully through the detector (Courtesy of Lassi Tuura)

  4. Beam halo in high-intensity beams

    International Nuclear Information System (INIS)

    Wangler, T.P.

    1993-01-01

    In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. The beam-halo is of concern for a next generation of cw, high-power proton linacs that could be applied to intense neutron generators for nuclear materials processing. The author describes what has been learned about beam halo and the evolution of space-charge dominated beams using numerical simulations of initial laminar beams in uniform linear focusing channels. Initial results are presented from a study of beam entropy for an intense space-charge dominated beam

  5. BEAM-FORMING ERRORS IN MURCHISON WIDEFIELD ARRAY PHASED ARRAY ANTENNAS AND THEIR EFFECTS ON EPOCH OF REIONIZATION SCIENCE

    Energy Technology Data Exchange (ETDEWEB)

    Neben, Abraham R.; Hewitt, Jacqueline N.; Dillon, Joshua S.; Goeke, R.; Morgan, E. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Bradley, Richard F. [Dept. of Electrical and Computer Engineering, University of Virginia, Charlottesville, VA, 22904 (United States); Bernardi, G. [Square Kilometre Array South Africa (SKA SA), Cape Town 7405 (South Africa); Bowman, J. D. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Briggs, F. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Cappallo, R. J.; Corey, B. E.; Lonsdale, C. J.; McWhirter, S. R. [MIT Haystack Observatory, Westford, MA 01886 (United States); Deshpande, A. A. [Raman Research Institute, Bangalore 560080 (India); Greenhill, L. J. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Hazelton, B. J.; Morales, M. F. [Department of Physics, University of Washington, Seattle, WA 98195 (United States); Johnston-Hollitt, M. [School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6140 (New Zealand); Kaplan, D. L. [Department of Physics, University of Wisconsin–Milwaukee, Milwaukee, WI 53201 (United States); Mitchell, D. A. [CSIRO Astronomy and Space Science (CASS), P.O. Box 76, Epping, NSW 1710 (Australia); and others

    2016-03-20

    Accurate antenna beam models are critical for radio observations aiming to isolate the redshifted 21 cm spectral line emission from the Dark Ages and the Epoch of Reionization (EOR) and unlock the scientific potential of 21 cm cosmology. Past work has focused on characterizing mean antenna beam models using either satellite signals or astronomical sources as calibrators, but antenna-to-antenna variation due to imperfect instrumentation has remained unexplored. We characterize this variation for the Murchison Widefield Array (MWA) through laboratory measurements and simulations, finding typical deviations of the order of ±10%–20% near the edges of the main lobe and in the sidelobes. We consider the ramifications of these results for image- and power spectrum-based science. In particular, we simulate visibilities measured by a 100 m baseline and find that using an otherwise perfect foreground model, unmodeled beam-forming errors severely limit foreground subtraction accuracy within the region of Fourier space contaminated by foreground emission (the “wedge”). This region likely contains much of the cosmological signal, and accessing it will require measurement of per-antenna beam patterns. However, unmodeled beam-forming errors do not contaminate the Fourier space region expected to be free of foreground contamination (the “EOR window”), showing that foreground avoidance remains a viable strategy.

  6. Single-pass high-gain tapered free-electron laser with transverse diffraction in the postsaturation regime

    Directory of Open Access Journals (Sweden)

    Cheng-Ying Tsai

    2018-06-01

    Full Text Available It has been well known that the resonant interaction of an ultrarelativistic electron beam and the radiation field in the single-pass high-gain free electron laser (FEL amplifier leads to the optical gain guiding. The transverse Laplacian term of the slowly varying wave equation in the linear regime can be approximated as a constant detuning parameter, i.e., |∇_{⊥}^{2}|∼k_{R}/z_{R} where k_{R} is the resonant wave number and z_{R} is the Rayleigh range of the laser. In the post-saturation regime, the radiation power begins to oscillate about an equilibrium for the untapered case while continues to grow by undulator tapering. Moreover, in this regime the gain guiding decreases and the simple constant detune is no longer valid. In this paper we study the single-pass high-gain FEL performance in the post-saturation regime with inclusion of diffraction effect and undulator tapering. Our analysis relies upon two constants of motion, one from the energy conservation and the other from the adiabatic invariant of the action variable. By constructing a two-dimensional axisymmetric wave equation and the coupled one-dimensional electron dynamical equations, the performance of a tapered FEL in the postsaturation regime can be analyzed, including the fundamental mode profile, the power efficiency and the scaled energy spread. We begin the analytical investigation with two different axisymmetric electron beam profiles, the uniform and bounded parabolic ones. It is found that the tapered FEL power efficiency can be smaller but close to the taper ratio provided the resonant phase remains constant and the beam-wave is properly matched. Such a tapered efficiency is nearly independent of transverse electron beam size before significant electron detrapping occurs. This is essentially different from the untapered case, where the power extraction efficiency is around the essential FEL gain bandwidth (or ρ, the Pierce or FEL parameter and depends on the beam

  7. Wave-optical evaluation of interference fringes and wavefront phase in a hard-x-ray beam totally reflected by mirror optics.

    Science.gov (United States)

    Yamauchi, Kazuto; Yamamura, Kazuya; Mimura, Hidekazu; Sano, Yasuhisa; Saito, Akira; Endo, Katsuyoshi; Souvorov, Alexei; Yabashi, Makina; Tamasaku, Kenji; Ishikawa, Tetsuya; Mori, Yuzo

    2005-11-10

    The intensity flatness and wavefront shape in a coherent hard-x-ray beam totally reflected by flat mirrors that have surface bumps modeled by Gaussian functions were investigated by use of a wave-optical simulation code. Simulated results revealed the necessity for peak-to-valley height accuracy of better than 1 nm at a lateral resolution near 0.1 mm to remove high-contrast interference fringes and appreciable wavefront phase errors. Three mirrors that had different surface qualities were tested at the 1 km-long beam line at the SPring-8/Japan Synchrotron Radiation Research Institute. Interference fringes faded when the surface figure was corrected below the subnanometer level to a spatial resolution close to 0.1 mm, as indicated by the simulated results.

  8. Triplets pass their pressure test

    CERN Multimedia

    2007-01-01

    All the LHC inner triplets have now been repaired and are in position. The first ones have passed their pressure tests with flying colours. The repaired inner triplet at LHC Point 1, right side (1R). Ranko Ostojic (on the right), who headed the team responsible for repairing the triplets, shows the magnet to Robert Zimmer, President of the University of Chicago and of Fermi Research Alliance, who visited CERN on 20th August.Three cheers for the triplets! All the LHC inner triplets have now been repaired and are in position in the tunnel. Thanks to the mobilisation of a multidisciplinary team from CERN and Fermilab, assisted by the KEK Laboratory and the Lawrence Berkeley National Laboratory (LBNL), a solution has been found, tested, validated and applied. At the end of March this year, one of the inner triplets at Point 5 failed to withstand a pressure test. A fault was identified in the supports of two out of the three quadruple magne...

  9. Simulations of x-ray speckle-based dark-field and phase-contrast imaging with a polychromatic beam

    Energy Technology Data Exchange (ETDEWEB)

    Zdora, Marie-Christine, E-mail: marie-christine.zdora@diamond.ac.uk [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Department of Physics & Astronomy, University College London, London WC1E 6BT (United Kingdom); Thibault, Pierre [Department of Physics & Astronomy, University College London, London WC1E 6BT (United Kingdom); Pfeiffer, Franz [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Zanette, Irene [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom)

    2015-09-21

    Following the first experimental demonstration of x-ray speckle-based multimodal imaging using a polychromatic beam [I. Zanette et al., Phys. Rev. Lett. 112(25), 253903 (2014)], we present a simulation study on the effects of a polychromatic x-ray spectrum on the performance of this technique. We observe that the contrast of the near-field speckles is only mildly influenced by the bandwidth of the energy spectrum. Moreover, using a homogeneous object with simple geometry, we characterize the beam hardening artifacts in the reconstructed transmission and refraction angle images, and we describe how the beam hardening also affects the dark-field signal provided by speckle tracking. This study is particularly important for further implementations and developments of coherent speckle-based techniques at laboratory x-ray sources.

  10. Linear Fixed-Field Multi-Pass Arcs for Recirculating Linear Accelerators

    International Nuclear Information System (INIS)

    Morozov, V.S.; Bogacz, S.A.; Roblin, Y.R.; Beard, K.B.

    2012-01-01

    Recirculating Linear Accelerators (RLA's) provide a compact and efficient way of accelerating particle beams to medium and high energies by reusing the same linac for multiple passes. In the conventional scheme, after each pass, the different energy beams coming out of the linac are separated and directed into appropriate arcs for recirculation, with each pass requiring a separate fixed-energy arc. In this paper we present a concept of an RLA return arc based on linear combined-function magnets, in which two and potentially more consecutive passes with very different energies are transported through the same string of magnets. By adjusting the dipole and quadrupole components of the constituting linear combined-function magnets, the arc is designed to be achromatic and to have zero initial and final reference orbit offsets for all transported beam energies. We demonstrate the concept by developing a design for a droplet-shaped return arc for a dog-bone RLA capable of transporting two beam passes with momenta different by a factor of two. We present the results of tracking simulations of the two passes and lay out the path to end-to-end design and simulation of a complete dog-bone RLA.

  11. Induced Kerr effects and self-guided beams in quasi-phase-matched quadratic media [CBC4

    DEFF Research Database (Denmark)

    Clausen, Carl A. Balslev; Bang, Ole; Kivshar, Yuri S.

    1997-01-01

    We show that quasi-phase-matching of quadratic media induces Kerr effects, such as self- and cross-phase modulation, and leads to the existence of a novel class of solitary waves, QPM-solitons......We show that quasi-phase-matching of quadratic media induces Kerr effects, such as self- and cross-phase modulation, and leads to the existence of a novel class of solitary waves, QPM-solitons...

  12. Modeling the TrueBeam linac using a CAD to Geant4 geometry implementation: Dose and IAEA-compliant phase space calculations

    International Nuclear Information System (INIS)

    Constantin, Magdalena; Perl, Joseph; LoSasso, Tom; Salop, Arthur; Whittum, David; Narula, Anisha; Svatos, Michelle; Keall, Paul J.

    2011-01-01

    Purpose: To create an accurate 6 MV Monte Carlo simulation phase space for the Varian TrueBeam treatment head geometry imported from cad (computer aided design) without adjusting the input electron phase space parameters. Methods: geant4 v4.9.2.p01 was employed to simulate the 6 MV beam treatment head geometry of the Varian TrueBeam linac. The electron tracks in the linear accelerator were simulated with Parmela, and the obtained electron phase space was used as an input to the Monte Carlo beam transport and dose calculations. The geometry components are tessellated solids included in geant4 as gdml (generalized dynamic markup language) files obtained via STEP (standard for the exchange of product) export from Pro/Engineering, followed by STEP import in Fastrad, a STEP-gdml converter. The linac has a compact treatment head and the small space between the shielding collimator and the divergent arc of the upper jaws forbids the implementation of a plane for storing the phase space. Instead, an IAEA (International Atomic Energy Agency) compliant phase space writer was implemented on a cylindrical surface. The simulation was run in parallel on a 1200 node Linux cluster. The 6 MV dose calculations were performed for field sizes varying from 4 x 4 to 40 x 40 cm 2 . The voxel size for the 60x60x40 cm 3 water phantom was 4x4x4 mm 3 . For the 10x10 cm 2 field, surface buildup calculations were performed using 4x4x2 mm 3 voxels within 20 mm of the surface. Results: For the depth dose curves, 98% of the calculated data points agree within 2% with the experimental measurements for depths between 2 and 40 cm. For depths between 5 and 30 cm, agreement within 1% is obtained for 99% (4x4), 95% (10x10), 94% (20x20 and 30x30), and 89% (40x40) of the data points, respectively. In the buildup region, the agreement is within 2%, except at 1 mm depth where the deviation is 5% for the 10x10 cm 2 open field. For the lateral dose profiles, within the field size for fields up to 30x30 cm 2

  13. Modeling the TrueBeam linac using a CAD to Geant4 geometry implementation: Dose and IAEA-compliant phase space calculations

    Energy Technology Data Exchange (ETDEWEB)

    Constantin, Magdalena; Perl, Joseph; LoSasso, Tom; Salop, Arthur; Whittum, David; Narula, Anisha; Svatos, Michelle; Keall, Paul J. [Department of Radiation Oncology, Radiation Physics Division, Stanford University, Stanford, California 94304 (United States); SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Memorial Sloan-Kettering Cancer Center, New York 10021 (United States); Varian Medical Systems, Inc., Palo Alto, California 94304 (United States); Department of Radiation Oncology, Radiation Physics Division, Stanford University, Stanford, California 94304 (United States)

    2011-07-15

    Purpose: To create an accurate 6 MV Monte Carlo simulation phase space for the Varian TrueBeam treatment head geometry imported from cad (computer aided design) without adjusting the input electron phase space parameters. Methods: geant4 v4.9.2.p01 was employed to simulate the 6 MV beam treatment head geometry of the Varian TrueBeam linac. The electron tracks in the linear accelerator were simulated with Parmela, and the obtained electron phase space was used as an input to the Monte Carlo beam transport and dose calculations. The geometry components are tessellated solids included in geant4 as gdml (generalized dynamic markup language) files obtained via STEP (standard for the exchange of product) export from Pro/Engineering, followed by STEP import in Fastrad, a STEP-gdml converter. The linac has a compact treatment head and the small space between the shielding collimator and the divergent arc of the upper jaws forbids the implementation of a plane for storing the phase space. Instead, an IAEA (International Atomic Energy Agency) compliant phase space writer was implemented on a cylindrical surface. The simulation was run in parallel on a 1200 node Linux cluster. The 6 MV dose calculations were performed for field sizes varying from 4 x 4 to 40 x 40 cm{sup 2}. The voxel size for the 60x60x40 cm{sup 3} water phantom was 4x4x4 mm{sup 3}. For the 10x10 cm{sup 2} field, surface buildup calculations were performed using 4x4x2 mm{sup 3} voxels within 20 mm of the surface. Results: For the depth dose curves, 98% of the calculated data points agree within 2% with the experimental measurements for depths between 2 and 40 cm. For depths between 5 and 30 cm, agreement within 1% is obtained for 99% (4x4), 95% (10x10), 94% (20x20 and 30x30), and 89% (40x40) of the data points, respectively. In the buildup region, the agreement is within 2%, except at 1 mm depth where the deviation is 5% for the 10x10 cm{sup 2} open field. For the lateral dose profiles, within the field size

  14. Beam-Beam Interaction Studies at LHC

    CERN Document Server

    Schaumann, Michaela; Alemany Fernandez, R

    2011-01-01

    The beam-beam force is one of the most important limiting factors in the performance of a collider, mainly in the delivered luminosity. Therefore, it is essential to measure the effects in LHC. Moreover, adequate understanding of LHC beam-beam interaction is of crucial importance in the design phases of the LHC luminosity upgrade. Due to the complexity of this topic the work presented in this thesis concentrates on the beam-beam tune shift and orbit effects. The study of the Linear Coherent Beam-Beam Parameter at the LHC has been determined with head-on collisions with small number of bunches at injection energy (450 GeV). For high bunch intensities the beam-beam force is strong enough to expect orbit effects if the two beams do not collide head-on but with a crossing angle or with a given offset. As a consequence the closed orbit changes. The closed orbit of an unperturbed machine with respect to a machine where the beam-beam force becomes more and more important has been studied and the results are as well ...

  15. Current trends in laser fusion driver and beam combination laser system using stimulated Brillouin scattering phase conjugate mirrors for a fusion driver

    International Nuclear Information System (INIS)

    Kong, Hong Jin

    2008-01-01

    Laser fusion energy (LFE) is well known as one of the promising sources if clean energy for mankind. Laser fusion researches have been actively progressed, since Japan and the Soviet Union as well as USA developed ultrahigh power lasers at the beginning of 1970s. At present in USA, NIF (National Ignition Facility), which is the largest laser fusion facility in the world, is under construction and will be completed in 2008. Japan as a leader of the laser fusion research has developed a high energy and high power laser system, Gekko XII, and is under contemplation of FIREX projects for the fast ignition. China also has SG I, II lasers for performing the fusion research, and SG III is under construction as a next step. France is also constructing LMJ (Laser countries, many other developed countries in Europe, such as Russia, Germany, UK, and so on, have their own high energy laser systems for the fusion research. In Korea, the high power laser development started with SinMyung laser in KAIST in 1994, and KLF (KAERI Laser Facility) of KAERI was recently completed in 2007. For the practical use of laser fusion energy, the laser driver should be operated with a high repetition rate around 10Hz. Yet, current high energy laser systems, Such as NIF, Gekko XII, and etc., can be operated with only several shots per day. Some researchers have developed their own techniques to reduce the thermal loads of the laser material, by using laser diodes as pump sources and ceramic laser materials with high thermal energy scaling up for the real fusion driver. For this reason, H. J. Kong et al. proposed the beam combination laser system using stimulated Brillouin scattering phase conjugate mirrors (SBS PCMs) for a fusion driver. Proposed beam combination has many advantages for energy scaling up; it is composed by simple optical systems with small amount of components, there is no interaction between neighbored sub beams, the SBS PCMs can be used for a high energy beam reflection with

  16. Ultra-Short Electron Beam Compression and Phase Locking Using an Inverse Free Electron Laser Interaction in the THz Regime

    International Nuclear Information System (INIS)

    Moody, J. T.; Musumeci, P.; Scoby, C. M.; To, H.; Marcoux, C.

    2010-01-01

    The concept of a THz-based IFEL compressor at the UCLA Pegasus photoinjector laboratory is explored. A 3.5 MeV sub-picosecond electron beam generated in the photoinjector blowout regime can be compressed to femtosecond timescales by a THz IFEL interaction.

  17. Condition assessment and methods of abatement of prestressed concrete box-beam deterioration, phase II : volume 1.

    Science.gov (United States)

    2009-04-13

    Side-by-side box-beam bridge constitutes approximately 17 percent of bridges built or replaced annually on : public roads and there is a renewed thrust to use this bridge type for rapid construction under the Highway for : LIFE program. Further, fail...

  18. Condition assessment and methods of abatement of prestressed concrete box-beam deterioration, phase II : volume 2.

    Science.gov (United States)

    2009-04-13

    Side-by-side box-beam bridge constitutes approximately 17 percent of bridges built or replaced annually on public roads and there is a renewed thrust to use this bridge type for rapid construction under the Highway for LIFE program. Further, failure ...

  19. Longitudinal Diagnostics for Short Electron Beam Bunches

    Energy Technology Data Exchange (ETDEWEB)

    Loos, H.; /SLAC

    2010-06-11

    Single-pass free electron lasers require high peak currents from ultra-short electron bunches to reach saturation and an accurate measurement of bunch length and longitudinal bunch profile is necessary to control the bunch compression process from low to high beam energy. The various state-of-the-art diagnostics methods from ps to fs time scales using coherent radiation detection, RF deflection, and other techniques are presented. The use of linear accelerators as drivers for free electron lasers (FEL) and the advent of single-pass (SASE) FELs has driven the development of a wide range of diagnostic techniques for measuring the length and longitudinal distribution of short and ultra-short electron bunches. For SASE FELs the radiation power and the length of the undulator needed to achieve saturation depend strongly on the charge density of the electron beam. In the case of X-ray FELs, this requires the accelerator to produce ultra-high brightness beams with micron size transverse normalized emittances and peak currents of several kA through several stages of magnetic bunch compression. Different longitudinal diagnostics are employed to measure the peak current and bunch profile along these stages. The measurement techniques can be distinguished into different classes. Coherent methods detect the light emitted from the beam by some coherent radiation process (spectroscopic measurement), or directly measure the Coulomb field traveling with the beam (electro-optic). Phase space manipulation techniques map the time coordinate onto a transverse dimension and then use conventional transverse beam diagnostics (transverse deflector, rf zero-phasing). Further methods measure the profile or duration of an incoherent light pulse emitted by the bunch at wavelengths much shorted than the bunch length (streak camera, fluctuation technique) or modulate the electron beam at an optical wavelength and then generate a narrow bandwidth radiation pulse with the longitudinal profile of

  20. Analysis of the unmodulated diffraction beam of the phase-only liquid crystal spatial light modulator and a method for reducing its influence

    International Nuclear Information System (INIS)

    Qi, Yue; Li, Dayu; Hu, Lifa; Xuan, Li; Xia, Mingliang

    2012-01-01

    As a wavefront corrector, the phase-only liquid crystal spatial light modulator has been widely using in adaptive optics systems. However, the unmodulated diffracted beam of the modulator will affect the light spot centroid detection accuracy of a Shack–Hartmann wavefront sensor and decrease the image quality after correction. In this paper, we have diminished the effect by introducing a modified weight algorithm in our closed-loop adaptive optics system. The Strehl ratio of the image is higher than 0.8 after correction, even when the wavefront aberration is larger than 3 μm. The correction precision and image quality are both improved significantly. (paper)

  1. A Tunable CW Orange Laser Based on a Cascaded MgO:PPLN Single-Pass Sum-Frequency Generation Module

    OpenAIRE

    Dismas K. Choge; Huai-Xi Chen; Bao-Lu Tian; Yi-Bin Xu; Guang-Wei Li; Wan-Guo Liang

    2018-01-01

    We report an all-solid-state continuous wave (CW) tunable orange laser based on cascaded single-pass sum-frequency generation with fundamental wavelengths at 1545.7 and 975.2 nm using two quasi-phase-matched (QPM) MgO-doped periodically poled lithium niobate (MgO:PPLN) crystals. Up to 10 mW of orange laser is generated in the cascaded module corresponding to a 10.4%/W nonlinear conversion efficiency. The orange output showed a temperature tuning rate of ~0.05 nm/°C, and the beam quality (M2) ...

  2. MTN magnet for the SPS extracted beam.

    CERN Document Server

    CERN PhotoLab

    1976-01-01

    This type of dipole magnet was used in the extracted beam lines of the North Area. It shows an opening for three different proton beam lines: a primary extracted proton beam, split by an upstream magnetic beam splitter (see photo 7612017) into three separated beams passes through different parts of its aperture: right, left up, left down. These magnets were designed to be concrete-insulated for radiation resistance. F. Streun stands on the right.

  3. Longitudinal coupling impedance imposed by a beam feedback in a synchrotron

    International Nuclear Information System (INIS)

    Ivanov, S.

    1997-01-01

    Commonly, a longitudinal beam feedback processes a slowly varying signal at zero intermediate frequency (a phase offset, an amplitude departure). Often, only a portion of the data confined in a picked-up band-pass beam signal is retained (like, say, in a purely phase feedback). Sometimes, a beam feedback employs different RF bands to pick up beam data and return a correction back to the beam. All the manipulations thus involved with signal spectra result in cross-talk between various beam-current and electric-field waves propagating along the orbit, which is shown to be described by an impedance matrix with, at most, three non-trivial elements per row. It is this matrix which gives the intuitive notion that a linear feedback is seen by a beam as an artificial coupling impedance controlled from the outside from a quantitative basis. This (impedance) approach has at least two plain advantages: (i) It allows one to mount the feedback's effect into the well-established theory of longitudinal coherent instabilities to use most of its inventory: beam transfer functions, threshold maps, handling of coupled-bunch motion, etc. (ii) The destabilizing effect of the beam environment, being available in standard terms of coupling impedances, is naturally taken into account since the early stages of feedback R and D. (orig.)

  4. A prototype for the PASS Permanent All Sky Survey

    Science.gov (United States)

    Deeg, H. J.; Alonso, R.; Belmonte, J. A.; Horne, K.; Alsubai, K.; Collier Cameron, A.; Doyle, L. R.

    2004-10-01

    A prototype system for the Permanent All Sky Survey (PASS) project is presented. PASS is a continuous photometric survey of the entire celestial sphere with a high temporal resolution. Its major objectives are the detection of all giant-planet transits (with periods up to some weeks) across stars up to mag 10.5, and to deliver continuously photometry that is useful for the study of any variable stars. The prototype is based on CCD cameras with short focal length optics on a fixed mount. A small dome to house it at Teide Observatory, Tenerife, is currently being constructed. A placement at the antarctic Dome C is also being considered. The prototype will be used for a feasibility study of PASS, to define the best observing strategies, and to perform a detailed characterization of the capabilities and scope of the survey. Afterwards, a first partial sky surveying will be started with it. That first survey may be able to detect transiting planets during its first few hundred hours of operation. It will also deliver a data set around which software modules dealing with the various scientific objectives of PASS will be developed. The PASS project is still in its early phase and teams interested in specific scientific objectives, in providing technical expertise, or in participating with own observations are invited to collaborate.

  5. Investigations of the phase transition in V3O5 using energy dispersive X-ray diffraction and synchrotron radiation white beam X-ray topography

    International Nuclear Information System (INIS)

    Asbrink, S.; Gerward, L.; Staun Olsen, J.

    1985-01-01

    The reversible first order phase transition in V 3 O 5 at T t =155 0 C has been studied using a specially constructed oven, where the temperature can be kept constant within a few hundredths of a degree for several hours. Energy dispersive diffraction measurements have beem made in a temperature region around the phase transition with the fixed crystal method and the θ/2θ scanning method. White beam X-ray topographs have been obtained from the same crystal in the same temperature region using synchrotron radiation. The integrated intensities of the strong h 0 0 reflections show anomalies that are correlated with the corresponding X-ray topographs. Thus, an unexpected increase of crystal perfection is observed a few hundredths of a degree below T t . The energy dependence of the intensity maximum at T t for strong reflections has been determined and semi-quantitatively explained on the basis of extinction theory. (orig.)

  6. Evolution of High Intensity Beams in the CERN PS Booster after H⁻ Injection and Phase Space Painting

    CERN Document Server

    Cieslak-Kowalska, Magdalena; Benedetto, Elena; Bracco, Chiara

    2016-01-01

    With the LHC Injector Upgrade (LIU) project, the injection energy of PS Booster (PSB) ' first circular accelerator in the LHC injector chain ' will be raised from 50 MeV to 160 MeV and the present multiturn injection will be upgraded to H⁻ injection with transverse and longitudinal painting. In the scope of this project, it is planned to double the beam intensities, profiting from the fact that the βγ2 factor will be two times larger (0.35 at 50 MeV and 0.71 at 160 MeV), so the resulting tune spread driven by a direct space charge should remain similar. This paper describes the feasibility to double the intensity of high intensity and large emittance beams, looking into the evolution under space charge and taking into account losses constrains in the ring and in the extraction lines.

  7. Oil price pass-through into inflation

    International Nuclear Information System (INIS)

    Chen, Shiu-Sheng

    2009-01-01

    This paper uses data from 19 industrialized countries to investigate oil price pass-through into inflation across countries and over time. A time-varying pass-through coefficient is estimated and the determinants of the recent declining effects of oil shocks on inflation are investigated. The appreciation of the domestic currency, a more active monetary policy in response to inflation, and a higher degree of trade openness are found to explain the decline in oil price pass-through. (author)

  8. Possibilities of the fish pass restoration

    Science.gov (United States)

    Čubanová, Lea

    2018-03-01

    According to the new elaborated methodology of the Ministry of Environment of the Slovak Republic: Identification of the appropriate fish pass types according to water body typology (2015) each barrier on the river must be passable. On the barriers or structures without fish passes new ones should be design and built and on some water structures with existed but nonfunctional fish passes must be realized reconstruction or restoration of such objects. Assessment should be done in terms of the existing migratory fish fauna and hydraulic conditions. Fish fauna requirements resulting from the ichthyological research of the river section with barrier. Hydraulic conditions must than fulfil these requirements inside the fish pass body.

  9. Dynamic beam cleaning by a nonlinear resonance

    Energy Technology Data Exchange (ETDEWEB)

    Chao, A W; Month, M [Brookhaven National Lab., Upton, N.Y. (USA)

    1976-03-15

    The general framework for the dynamic cleaning of a stored proton beam by passing the beam through a nonlinear resonance is developed. The limitations and advantages of this technique are discussed. The method is contrasted with physical beam scraping, which is currently in use at the CERN ISR.

  10. Milestone experiments for single pass UV/X-ray FELs

    International Nuclear Information System (INIS)

    Ben-Zvi, I.

    1994-01-01

    In the past decade, significant advances have been made in the theory and technology of high brightness electron beams and single pass FELS. These developments facilitate the construction of practical UV and X-ray FELs and has prompted proposals to the DOE for the construction of such facilities. There are several important experiments to be performed before committing to the construction of dedicated user facilities. Two experiments are under construction in the IR, the UCLA Self Amplified Spontaneous Emission experiment and the BNL laser seeded Harmonic Generation experiment. A multi-institution collaboration is being organized about a 210 MeV electron linac available at BNL and the 10 meter tong NISUS wiggler. This experiment will be done in the UV and will test various experimental aspects of electron beam dynamics, FEL exponential regime with gain guiding, start up from noise, seeding and harmonic generation. These experiments will advance the state of FEL research and lead towards future dedicated users' facilities

  11. Beam director design report

    International Nuclear Information System (INIS)

    Younger, F.C.

    1986-08-01

    A design and fabrication effort for a beam director is documented. The conceptual design provides for the beam to pass first through a bending and focusing system (or ''achromat''), through a second achromat, through an air-to-vacuum interface (the ''beam window''), and finally through the vernier steering system. Following an initial concept study for a beam director, a prototype permanent magnet 30 0 beam-bending achromat and prototype vernier steering magnet were designed and built. In volume II, copies are included of the funding instruments, requests for quotations, purchase orders, a complete set of as-built drawings, magnetic measurement reports, the concept design report, and the final report on the design and fabrication project

  12. Astor Pass Seismic Surveys Preliminary Report

    Energy Technology Data Exchange (ETDEWEB)

    Louie, John [UNR; Pullammanappallil, Satish [Optim; Faulds, James; Eisses, Amy; Kell, Annie; Frary, Roxanna; Kent, Graham

    2011-08-05

    In collaboration with the Pyramid Lake Paiute Tribe (PLPT), the University of Nevada, Reno (UNR) and Optim re-processed, or collected and processed, over 24 miles of 2d seismic-reflection data near the northwest corner of Pyramid Lake, Nevada. The network of 2d land surveys achieved a near-3d density at the Astor Pass geothermal prospect that the PLPT drilled during Nov. 2010 to Feb. 2011. The Bureau of Indian Affairs funded additional seismic work around the Lake, and an extensive, detailed single-channel marine survey producing more than 300 miles of section, imaging more than 120 ft below the Lake bottom. Optim’s land data collection utilized multiple heavy vibrators and recorded over 200 channels live, providing a state-of-the-art reflection-refraction data set. After advanced seismic analysis including first-arrival velocity optimization and prestack depth migration, the 2d sections show clear fault-plane reflections, in some areas as deep as 4000 ft, tying to distinct terminations of the mostly volcanic stratigraphy. Some lines achieved velocity control to 3000 ft depth; all lines show reflections and terminations to 5000 ft depth. Three separate sets of normal faults appear in an initial interpretation of fault reflections and stratigraphic terminations, after loading the data into the OpendTect 3d seismic visualization system. Each preliminary fault set includes a continuous trace more than 3000 ft long, and a swarm of short fault strands. The three preliminary normal-fault sets strike northerly with westward dip, northwesterly with northeast dip, and easterly with north dip. An intersection of all three fault systems documented in the seismic sections at the end of Phase I helped to locate the APS-2 and APS-3 slimholes. The seismic sections do not show the faults connected to the Astor Pass tufa spire, suggesting that we have imaged mostly Tertiary-aged faults. We hypothesize that the Recent, active faults that produced the tufa through hotspring

  13. A new concept for the control of a slow-extracted beam in a line with rotational optics: Part II

    CERN Document Server

    Benedikt, Michael; Pullia, M

    1999-01-01

    The current trend in hadrontherapy is towards high-precision, conformal scanning of tumours with a 'pencil' beam of light ions or protons, delivered by a synchrotron using slow extraction. The particular shape of the slow-extracted beam segment in phase space and the need to vary the beam size in a lattice with rotating optical elements create a special problem for the design of the extraction transfer line and gantry. The design concept presented in this report is based on telescope modules with integer-pi phase advances in both transverse planes. The beam size in the plane of the extraction is controlled by altering the phase advance and hence the rotation of the extracted beam segment in phase space. The vertical beam size is controlled by stepping the vertical betatron amplitude function over a range of values and passing the changed beam size from 'hand-to-hand' through the telescope modules to the various treatment rooms. In the example given, a combined phase shifter and 'stepper', at a point close to ...

  14. A New Concept for the Control of a Slow-Extracted Beam in a Line with Rotational Optics, 2

    CERN Document Server

    Benedikt, Michael; Pullia, M

    1999-01-01

    The current trend in hadrontherapy is towards high-precision, conformal scanning of tumours with a 'pencil' beam of light ions, or protons, delivered by a synchrotron using slow-extraction. The particular shape of the slow-extracted beam segment in phase space and the need to vary the beam size in a lattice with rotating optical elements create a special problem for the design of the extraction transfer line and gantry. The design concept presented in this report is based on telescope modules with integer-p phase advances in both transverse planes. The beam size in the plane of the extraction is controlled by altering the phase advance and hence the rotation of the extracted beam segment in phase space. The vertical beam size is controlled by stepping the vertical betatron amplitude function over a range of values and passing the changed beam size from 'hand-to-hand' through the telescope modules to the various treatment rooms. In the example given, a combined phase-shifter and 'stepper', at a point close to ...

  15. The measurement of stress and phase fraction distributions in pre and post-transition Zircaloy oxides using nano-beam synchrotron X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Swan, H., E-mail: helen.swan@nnl.co.uk [National Nuclear Laboratory, Building D5, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Blackmur, M.S., E-mail: matthew.s.blackmur@nnl.co.uk [National Nuclear Laboratory, Building D5, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Hyde, J.M., E-mail: jonathan.m.hyde@nnl.co.uk [National Nuclear Laboratory, Building D5, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Laferrere, A., E-mail: alice.laferrere@atkinsglobal.com [W.S.Atkins, The Hub, Aztec West, 500 Park Ave, Almondsbury, Bristol BS32 4RZ (United Kingdom); Ortner, S.R., E-mail: susan.r.ortner@nnl.co.uk [National Nuclear Laboratory, Building D5, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Styman, P.D., E-mail: paul.d.styman@nnl.co.uk [National Nuclear Laboratory, Building D5, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Staines, C., E-mail: cassie.staines@nnl.co.uk [National Nuclear Laboratory, 102B, Stonehouse Park, Stonehouse, Gloucestershire, GL10 3UT (United Kingdom); Gass, M., E-mail: mhairi.gass@amecfw.com [Amec Foster Wheeler Clean Energy Europe, Walton House, Birchwood, WA3 6GA (United Kingdom); Hulme, H., E-mail: helen.hulme@amecfw.com [Amec Foster Wheeler Clean Energy Europe, Walton House, Birchwood, WA3 6GA (United Kingdom); Cole-Baker, A., E-mail: aidan.cole-baker@rolls-royce.com [Rolls-Royce plc, PO Box 2000, Derby, DE21 7XX (United Kingdom); Frankel, P., E-mail: philipp.frankel@manchester.ac.uk [Materials Performance Centre, School of Materials, The University of Manchester, Manchester, M13 9PL (United Kingdom)

    2016-10-15

    Zircaloy-4 oxide stress profiles and tetragonal:monoclinic oxide phase fraction distributions were studied using nano-beam transmission X-ray diffraction. Continuous stress relief and phase transformation during the first cycle of oxide growth was observed. The in-plane monoclinic stress was shown to relax strongly up to each transition, whereas in-plane tetragonal stress-relief (near the metal-oxide interface) was only observed post transition. The research demonstrates that plasticity in the metal and the development of a band of in-plane cracking both relax the monoclinic in-plane stress. The observations are consistent with a model of transition in which in-plane cracking becomes interlinked prior to transition. These cracks, combined with the development of cracks with a through-thickness component (driven primarily by plasticity in the metal) and/or a porous network of fine cracks (associated with phase transformation), form a percolation path through the oxide layer. The oxidising species can then percolate from the oxide surface to the metal/oxide interface, at which stage transition then ensues. - Highlights: • Measurement of stress in Zr-4 oxides using nano-beam transmission X-ray diffraction. • In-plane monoclinic stress relaxes strongly up to each transition. • In-plane tetragonal stress relaxation is only observed post transition. • Development of band of cracking is related to monoclinic in-plane stress relaxation. • Linking of in-plane cracking with through-plane crack/porosity leads to transition.

  16. Beam Loss in Linacs

    CERN Document Server

    Plum, M.A.

    2016-01-01

    Beam loss is a critical issue in high-intensity accelerators, and much effort is expended during both the design and operation phases to minimize the loss and to keep it to manageable levels. As new accelerators become ever more powerful, beam loss becomes even more critical. Linacs for H- ion beams, such as the one at the Oak Ridge Spallation Neutron Source, have many more loss mechanisms compared to H+ (proton) linacs, such as the one being designed for the European Spallation Neutron Source. Interesting H- beam loss mechanisms include residual gas stripping, H+ capture and acceleration, field stripping, black-body radiation and the recently discovered intra-beam stripping mechanism. Beam halo formation, and ion source or RF turn on/off transients, are examples of beam loss mechanisms that are common for both H+ and H- accelerators. Machine protection systems play an important role in limiting the beam loss.

  17. A beam halo event of the ATLAS Experiment

    CERN Multimedia

    ATLAS, Experiment

    2014-01-01

    Beam halo events: These occur as a single beam of protons is circulating in one direction in LHC, just passing through ATLAS. An outlier particle hits a part of the detector causing a spray of particles.

  18. Simulations relevant to the beam instability in the foreshock

    International Nuclear Information System (INIS)

    Cairns, I.H.; Nishikawa, K.I.

    1989-01-01

    Electrons backstreaming into Earth's foreshock generate waves near the plasma frequency f p by the beam instability. Tow versions of the beam instability exist: the reactive version, in which narrow-band waves grow by bunching the electrons in space, and the kinetic version, in which broadband growth occurs by a maser mechanism. Recently, it has been suggested that (1) the backstreaming electrons have steep-sided cutoff distributions which are initially unstable to the reactive instability, (2) the back reaction to the wave growth causes the instability to pass into its kinetic phase, and (3) the kinetic instability saturates by quasi-linear relaxation. In this paper the authors present two-dimensional simulations of the reactive instability for Maxwellian beams and cutoff distributions. They demonstrate that the reactive instability is a bunching instability and that the reactive instability saturates and passes over into the kinetic phase by particle trapping.A reactive/kinetic transition is shown to most likely occur within 1 km and 50 km of the bow shock. They suggest that the frequency of the intense narrow-band waves decrease from above f p to perhaps 0.9f p (dependent on the beam density) with increasing penetration into the high beam speed region of the foreshock, before the wave frequency rises again as the waves become broadband deeper in the foreshock. Both the simulation results and numerical solutions of the dispersion equation indicate that for the observed beam parameters the center frequency of the waves near the foreshock boundary should be between 0.9f p and 0.98f p , rather than above f p as previously believed. The simulation results indicate that the effects of spatial inhomogeneity are vital for a quantitative understanding of the foreshock waves

  19. Improved double-pass michelson interferometer

    Science.gov (United States)

    Schindler, R. A.

    1978-01-01

    Interferometer design separates beams by offsetting centerlines of cat's-eye retroreflectors vertically rather than horizontally. Since beam splitter is insensitive to minimum-thickness condition in this geometry, relatively-low-cost, optically flat plate can be used.

  20. Natural Frequency Testing and Model Correlation of Rocket Engine Structures in Liquid Hydrogen - Phase I, Cantilever Beam

    Science.gov (United States)

    Brown, Andrew M.; DeLessio, Jennifer L.; Jacobs, Preston W.

    2018-01-01

    Many structures in the launch vehicle industry operate in liquid hydrogen (LH2), from the hydrogen fuel tanks through the ducts and valves and into the pump sides of the turbopumps. Calculating the structural dynamic response of these structures is critical for successful qualification of this hardware, but accurate knowledge of the natural frequencies is based entirely on numerical or analytical predictions of frequency reduction due to the added-fluid-mass effect because testing in LH2 has always been considered too difficult and dangerous. This fluid effect is predicted to be approximately 4-5% using analytical formulations for simple cantilever beams. As part of a comprehensive test/analysis program to more accurately assess pump inducers operating in LH2, a series of frequency tests in LH2 were performed at NASA/Marshall Space Flight Center's unique cryogenic test facility. These frequency tests are coupled with modal tests in air and water to provide critical information not only on the mass effect of LH2, but also the cryogenic temperature effect on Young's Modulus for which the data is not extensive. The authors are unaware of any other reported natural frequency testing in this media. In addition to the inducer, a simple cantilever beam was also tested in the tank to provide a more easily modeled geometry as well as one that has an analytical solution for the mass effect. This data will prove critical for accurate structural dynamic analysis of these structures, which operate in a highly-dynamic environment.

  1. A new approach in e-beam treatment of flue gases and other gas-phase processes

    International Nuclear Information System (INIS)

    Kukulin, V.I.

    1999-01-01

    A principally new approach avoiding the conventional ammonia (or limestone) technology for the e-beam treatment of flue gases in coal-fired electric power stations, boilers and ore smelting industries is suggested. The approach includes two stages. At the first stage the flue gases undergo hard ultra-violet irradiation (with an appropriate spectral distribution) in permanent electric field which leads to a partial separation of NO and SO 2 from the rest of flue gases. At the second stage this partially separated mixture of No and SO 2 undergoes a combined impact of a fast gaseous jet consisting of a molecular mixture N 2 +H 2 together with longitudinal collinear electron beam with maximal electron energy around 300-400 KeV only. This low energy electron irradiation leads in case of such a geometry to a simultaneous reduction of NO and SO 2 oxides to the clear air components (i.e. N 2 +H 2 O) and elementary sulphur respectively instead of a large mass of ammonium nitrates and sulphates in the traditional Ebara approach, Besides, the suggested two-stage process may lead to a very significant reduction in the energy consumption (of the accelerated electrons) and a sharp decrease in the gamma-radiational background. Due to its characteristic features, the process has a much higher potential for commercialisation and wide spreading

  2. A Phase II study of external-beam radiotherapy and endovascular brachytherapy with PTA and stenting for femoropopliteal artery restenosis

    International Nuclear Information System (INIS)

    Narayan, Kailash; Denton, Michael; Das, Ram; Bernshaw, David; Rolfo, Aldo; Dyk, Sylvia van; Mirakian, Alex

    2006-01-01

    Purpose: To assess the safety and seek evidence of efficacy of combined external-beam radiotherapy (EBRT) and endovascular brachytherapy in the treatment of stenotic vascular lesions. Methods and Materials: Seventeen patients with high risk for restenosis of femoropopliteal arteries were enrolled in this study from February 2000 to August 2002. The external beam radiotherapy regimen consisted of 10 Gy in 5 fractions of 2 Gy, starting on Day 0. This was followed on Day 6 by angiography, stent placement, and intraluminal brachytherapy to a dose of 10 Gy at 1.2 mm from stent surface. The EBRT was continued from the same day to another 10 Gy in 2 Gy daily fractions for 5 days. Results: The follow up ranged from 33 months to 60 months. At the time of analysis 15 of 17 patients were alive with patent stents. Of these, 10 were symptom-free. Two patients died of unrelated causes. Conclusions: The combination of EBRT and endovascular brachytherapy provided adequate dose distribution without any geographical miss or 'candy wrapper' restenosis. No incidence of aneurysmal dilation of radiated vascular segment was observed. The treatment was feasible, well tolerated, and achieved 88% stenosis free survival

  3. Beam-beam effects under the influence of external noise

    International Nuclear Information System (INIS)

    Ohmi, K

    2014-01-01

    Fast external noise, which gives fluctuation into the beam orbit, is discussed in connection with beam-beam effects. Phase noise from crab cavities and detection devices (position monitor) and kicker noise from the bunch by bunch feedback system are the sources. Beam-beam collisions with fast orbit fluctuations with turn by turn or multi-turn correlations, cause emittance growth and luminosity degradation. We discuss the tolerance of the noise amplitude for LHC and HL-LHC

  4. Full-Duplex Digital Communication on a Single Laser Beam

    Science.gov (United States)

    Hazzard, D. A.; MacCannell, J. A.; Lee, G.; Selves, E. R.; Moore, D.; Payne, J. A.; Garrett, C. D.; Dahlstrom, N.; Shay, T. M.

    2006-01-01

    A proposed free-space optical communication system would operate in a full-duplex mode, using a single constant-power laser beam for transmission and reception of binary signals at both ends of the free-space optical path. The system was conceived for two-way data communication between a ground station and a spacecraft in a low orbit around the Earth. It has been estimated that in this application, a data rate of 10 kb/s could be achieved at a ground-station-to-spacecraft distance of 320 km, using a laser power of only 100 mW. The basic system concept is also applicable to terrestrial free-space optical communications. The system (see figure) would include a diode laser at one end of the link (originally, the ground station) and a liquid-crystal- based retroreflecting modulator at the other end of the link (originally, the spacecraft). At the laser end, the beam to be transmitted would be made to pass through a quarter-wave plate, which would convert its linear polarization to right circular polarization. For transmission of data from the laser end to the retroreflector end, the laser beam would be modulated with subcarrier phase-shift keying (SC-PSK). The transmitted beam would then pass through an aperture- sharing element (ASE) - basically, a mirror with a hole in it, used to separate the paths of the transmitted and received light beams. The transmitted beam would continue outward through a telescope (which, in the original application, would be equipped with a spacecraft-tracking system) that would launch the transmitted beam along the free-space optical path to the retroreflector end.

  5. Effect of the Gouy phase on the coherent phase control of chemical reactions.

    Science.gov (United States)

    Gordon, Robert J; Barge, Vishal J

    2007-11-28

    We show how the spatial phase of a focused laser beam may be used as a tool for controlling the branching ratio of a chemical reaction. Guoy discovered [Acad. Sci., Paris, C. R. 110, 1250 (1890)] that when an electromagnetic wave passes through a focus its phase increases by pi. In a coherent control scheme involving the absorption of n photons of frequency omega(m) and m photons of frequency omega(n), the overall phase shift produced by the Gouy phase is (n-m)pi. At any given point in space, this phase shift is identical for all reaction products. Nevertheless, if the yields for different reaction channels have different intensity dependencies, the Gouy phase produces a net phase lag between the products that varies with the axial coordinate of the laser focus. We obtain here analytical and numerical values of this phase as the laser focus is scanned across the diameter of the molecular beam, taking into account the Rayleigh range and astigmatism of the laser beam and saturation of the transition. We also show that the modulation depth of the interference pattern may be increased by optimizing the relative intensities of the two fields.

  6. Phase and group velocity tracing analysis of projected wave packet motion along oblique radar beams – qualitative analysis of QP echoes

    Directory of Open Access Journals (Sweden)

    F. S. Kuo

    2007-02-01

    Full Text Available The wave packets of atmospheric gravity waves were numerically generated, with a given characteristic wave period, horizontal wave length and projection mean wind along the horizontal wave vector. Their projection phase and group velocities along the oblique radar beam (vpr and vgr, with different zenith angle θ and azimuth angle φ, were analyzed by the method of phase- and group-velocity tracing. The results were consistent with the theoretical calculations derived by the dispersion relation, reconfirming the accuracy of the method of analysis. The RTI plot of the numerical wave packets were similar to the striation patterns of the QP echoes from the FAI irregularity region. We propose that the striation range rate of the QP echo is equal to the radial phase velocity vpr, and the slope of the energy line across the neighboring striations is equal to the radial group velocity vgr of the wave packet; the horizontal distance between two neighboring striations is equal to the characteristic wave period τ. Then, one can inversely calculate all the properties of the gravity wave responsible for the appearance of the QP echoes. We found that the possibility of some QP echoes being generated by the gravity waves originated from lower altitudes cannot be ruled out.

  7. A low background pulsed neutron polyenergetic beam at the ET-RR-1 reactor

    International Nuclear Information System (INIS)

    Adib, M.; Abdel-Kawy, A.; Habib, N.; Abu-El-Ela, M.; Wahba, M.; Kilany, M.

    1991-12-01

    A low background pulsed neutron polyenergetic thermal beam at ET-RR-1 is produced by a rotor and rotating collimator suspended in magnetic fields. Each of them is mounted on its mobile platform and whose centres are 66 cm apart, rotating synchronously at speeds up to 16000 rpm. It was found that the neutron burst produced by the rotor with almost 100% transmission passes through the collimator, when the rotation phase between them is 28.8 deg. Moreover the background level achieved at the detector position is low, constant and free from peaks due to gamma rays and fast neutrons accompanying the reactor thermal beam. (author). 12 refs, 3 figs

  8. First measurement of antikaon phase-space distributions in nucleus-nucleus collisions at subthreshold beam energies

    International Nuclear Information System (INIS)

    Menzel, M.; Boettcher, I.; Debowski, M.

    2000-10-01

    Differential production cross sections of K - and K + mesons have been measured as function of the polar emission angle in Ni+Ni collisions at a beam energy of 1.93 AGeV. In near-central collisions, the spectral shapes and the widths of the rapidity distributions of K - and K + mesons are in agreement with the assumption of isotropic emission. In non-central collisions, the K - and K + rapidity distributions are broader than expected for a single thermal source. In this case, the polar angle distributions are strongly forward-backward peaked and the non-isotropic contribution to the total yield is about one third both for K + and K - mesons. The K - /K + ratio is found to be about 0.03 independent of the centrality of the reaction. This value is significantly larger than predicted by microscopic transport calculations if in-medium modifications of K mesons are neglected. (orig.)

  9. Phase II study of concurrent capecitabine and external beam radiotherapy for pain control of bone metastases of breast cancer origin.

    Directory of Open Access Journals (Sweden)

    Yulia Kundel

    Full Text Available Pain from bone metastases of breast cancer origin is treated with localized radiation. Modulating doses and schedules has shown little efficacy in improving results. Given the synergistic therapeutic effect reported for combined systemic chemotherapy with local radiation in anal, rectal, and head and neck malignancies, we sought to evaluate the tolerability and efficacy of combined capecitabine and radiation for palliation of pain due to bone metastases from breast cancer.Twenty-nine women with painful bone metastases from breast cancer were treated with external beam radiation in 10 fractions of 3 Gy, 5 fractions a week for 2 consecutive weeks. Oral capecitabine 700 mg/m(2 twice daily was administered throughout radiation therapy. Rates of complete response, defined as a score of 0 on a 10-point pain scale and no increase in analgesic consumption, were 14% at 1 week, 38% at 2 weeks, 52% at 4 weeks, 52% at 8 weeks, and 48% at 12 weeks. Corresponding rates of partial response, defined as a reduction of at least 2 points in pain score without an increase in analgesics consumption, were 31%, 38%, 28%, 34% and 38%. The overall response rate (complete and partial at 12 weeks was 86%. Side effects were of mild intensity (grade I or II and included nausea (38% of patients, weakness (24%, diarrhea (24%, mucositis (10%, and hand and foot syndrome (7%.External beam radiation with concurrent capecitabine is safe and tolerable for the treatment of pain from bone metastases of breast cancer origin. The overall and complete response rates in our study are unusually high compared to those reported for radiation alone. Further evaluation of this approach, in a randomized study, is warranted.ClinicalTrials.gov NCT01784393NCT01784393.

  10. Broad-band beam buncher

    International Nuclear Information System (INIS)

    Goldberg, D.A.; Flood, W.S.; Arthur, A.A.; Voelker, F.

    1986-01-01

    This patent describes a broad-band beam buncher. This beam buncher consists of: a housing adapted to be eacuated, an electron gun in the housing for producing a beam of electrons, buncher means in the housing forming a buncher cavity which has an entrance opening for receiving the electron beam and an exit opening through which the electron beam passes out of the buncher cavity, a drift tube electrode in the buncher cavity and disposed between the entrance opening and the exit opening with first and second gaps between the drift tube electrode and the entrance and exit openings, the drift tube electrode which has a first drift space through which the electron beam passes in traveling between the entrance and exit openings, modulating means for supplying an ultrahigh frequeny modulating signal to the drift tube electrode for producing velocity modulation of the electrons in the electron beam as the electrons pass through the buncher cavity and the drift tube electrode between the entrance opening and the exit opening, drift space means in the housing forming a second drift space for receiving the velocity modulated electron beam from the exit opening, the velocity modulated electron beam being bunched as it passes along the second drift space, the drift space means has a discharge opening through which the electron beam is discharged from the second drift space after being bunched therein, the modulating means containing a signal source for producing an ultrahigh frequency signal, a transmission line connected between the signal source and the drift tube electrode, and terminating means connected to the drift tube electrode for terminating the transmission line in approximately its characteristic impedance to afford a broad response band with minimum 6 variations therein

  11. Applications of phase conjugate mirror to Thomson scattering diagnostics (invited)

    International Nuclear Information System (INIS)

    Hatae, T.; Naito, O.; Nakatsuka, M.; Yoshida, H.

    2006-01-01

    A high performance phase conjugate mirror based on stimulated Brillouin scattering (SBS-PCM) has been applied to the Thomson scattering system in the JT-60U tokamak for the first time in order to improve the measurement performance. A SBS-PCM realized a high reflectivity of 95% at a high input power of 145 W (2.9 J, 50 Hz). Using the SBS-PCM, two methods have been developed to increase the intensity of scattered light. For the first method, we have developed a new optical design to provide a double-pass scattering method with the SBS-PCM. A laser beam passing through the plasma is reflected by the SBS-PCM. The reflected beam passes the plasma again along the same path by means of the phase conjugation of the optically nonlinear stimulated Brillouin scattering process. The double-pass Thomson scattering method using the SBS-PCM has demonstrated an increase of the scattered light by a factor of 1.6 compared with the single-pass scattering method in JT-60U. A multipass Thomson scattering method in which the laser beam can be confined between a couple of SBS-PCMs is also proposed. It is estimated that the multipass scattering method generates the scattered light more than several times as large as that of the single-pass scattering method. For the second method, a high-average-power yttrium aluminum garnet (Nd:YAG) laser system has been developed using the SBS-PCM. The SBS-PCM effectively compensated thermal degradation at two amplifier lines, and the average power was increased by a factor of >8 from 45 W (1.5 J, 30 Hz) to 373 W (7.46 J, 50 Hz). A Nd:YAG laser (5 J, 100 Hz) for the edge Thomson scattering in International Thermonuclear Experimental Reactor (ITER) has been designed based on the result

  12. Novel Microstrip Patch Antennas with Frequency Agility, Polarization Reconfigurability, Dual Null Steering Capability and Phased Array Antenna with Beam Steering Performance

    Science.gov (United States)

    Babakhani, Behrouz

    Nowadays the wireless communication technology is playing an important role in our daily life. People use wireless devices not only as a conventional communication device but also as tracking and navigation tool, web browsing tool, data storage and transfer tool and so for many other reasons. Based on the user demand, wireless communication engineers try to accommodate as many as possible wireless systems and applications in a single device and therefore, creates a multifunctional device. Antenna, as an integral part of any wireless communication systems, should also be evolved and adjusted with development of wireless transceiver systems. Therefore multifunctional antennas have been introduced to support and enhance the functionality on modern wireless systems. The main focus and contribution of this thesis is design of novel multifunctional microstrip antennas with frequency agility, polarization reconfigurablity, dual null steering capability and phased array antenna with beam steering performance. In this thesis, first, a wide bandwidth(1.10 GHz to 1.60 GHz) right-handed circularly polarized (RHCP) directional antenna for global positioning system (GPS) satellite receive application has been introduced which covers all the GPS bands starting from L1 to L5. This design consists of two crossed bow-tie dipole antennas fed with sequentially phase rotated feed network backed with an artificial high impedance surface (HIS) structure to generate high gain directional radiation patterns. This design shows good CP gain and axial ratio (AR) and wide beamwidth performance. Although this design has good radiation quality, the size and the weight can be reduced as future study. In the second design, a frequency agile antenna was developed which also covers the L-band (L1 to L5) satellite communication frequencies. This frequency agile antenna was designed and realized by new implementation of varactor diodes in the geometry of a circular patch antenna. Beside wide frequency

  13. Exact solutions for the static bending of Euler-Bernoulli beams using Eringen’s two-phase local/nonlocal model

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y. B. [Department of Mathematics, ShaoXing University, No.900, ChengNan Avenue 312000, ShaoXing, Zhejiang (China); Zhu, X. W., E-mail: xiaowuzhu1026@znufe.edu.cn [School of Statistics and Mathematics, Zhongnan University of Economics and Law, Wuhan 430073 (China); Dai, H. H. [Department of Mathematics, City University of HongKong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong (China)

    2016-08-15

    Though widely used in modelling nano- and micro- structures, Eringen’s differential model shows some inconsistencies and recent study has demonstrated its differences between the integral model, which then implies the necessity of using the latter model. In this paper, an analytical study is taken to analyze static bending of nonlocal Euler-Bernoulli beams using Eringen’s two-phase local/nonlocal model. Firstly, a reduction method is proved rigorously, with which the integral equation in consideration can be reduced to a differential equation with mixed boundary value conditions. Then, the static bending problem is formulated and four types of boundary conditions with various loadings are considered. By solving the corresponding differential equations, exact solutions are obtained explicitly in all of the cases, especially for the paradoxical cantilever beam problem. Finally, asymptotic analysis of the exact solutions reveals clearly that, unlike the differential model, the integral model adopted herein has a consistent softening effect. Comparisons are also made with existing analytical and numerical results, which further shows the advantages of the analytical results obtained. Additionally, it seems that the once controversial nonlocal bar problem in the literature is well resolved by the reduction method.

  14. X-ray diffraction and imaging with a coherent beam: application to X-ray optical elements and to crystals exhibiting phase inhomogeneities

    International Nuclear Information System (INIS)

    Masiello, F.

    2011-05-01

    The exceptional properties of synchrotron light sources have been exploited in very different disciplines, from archaeology to chemistry, from material science to biology, from medicine to physics. Among these properties it is important to mention the high brilliance, continuum spectrum, high degree of polarization, time structure, small source size and divergence of the beam, the last resulting in a high transversal coherence of the produced radiation. This high transversal coherence of the synchrotron sources has permitted the development of new techniques, e.g. phase contrast imaging, X-ray photon correlation spectroscopy and coherent X-ray diffraction imaging (CXDI). This thesis work will consist essentially of three parts. In the first part it will be presented the work done as a member of the X-ray Optics Group of ESRF in the characterization of high quality diamond crystals foreseen as X-ray optical elements. The characterization has been done using different complementary X-ray techniques, such as high resolution diffraction, topography, grazing incidence diffraction, reflectivity and measurements of the coherence preservation using the Talbot effect. In the second part, I will show the result obtained in the study of the temperature behaviours of the domain in periodically poled ferroelectrics crystals. This type of measurements, based on Bragg-Fresnel diffraction, are possible only thanks to the high degree of coherence of the beam. In the third part, I will present the results obtained in the characterization of diamonds foreseen for applications other than X-ray optical elements. (author)

  15. Exact solutions for the static bending of Euler-Bernoulli beams using Eringen’s two-phase local/nonlocal model

    International Nuclear Information System (INIS)

    Wang, Y. B.; Zhu, X. W.; Dai, H. H.

    2016-01-01

    Though widely used in modelling nano- and micro- structures, Eringen’s differential model shows some inconsistencies and recent study has demonstrated its differences between the integral model, which then implies the necessity of using the latter model. In this paper, an analytical study is taken to analyze static bending of nonlocal Euler-Bernoulli beams using Eringen’s two-phase local/nonlocal model. Firstly, a reduction method is proved rigorously, with which the integral equation in consideration can be reduced to a differential equation with mixed boundary value conditions. Then, the static bending problem is formulated and four types of boundary conditions with various loadings are considered. By solving the corresponding differential equations, exact solutions are obtained explicitly in all of the cases, especially for the paradoxical cantilever beam problem. Finally, asymptotic analysis of the exact solutions reveals clearly that, unlike the differential model, the integral model adopted herein has a consistent softening effect. Comparisons are also made with existing analytical and numerical results, which further shows the advantages of the analytical results obtained. Additionally, it seems that the once controversial nonlocal bar problem in the literature is well resolved by the reduction method.

  16. Analyzing the propagation behavior of coherence and polarization degrees of a phase-locked partially coherent radial flat-topped array laser beam in underwater turbulence.

    Science.gov (United States)

    Kashani, Fatemeh Dabbagh; Yousefi, Masoud

    2016-08-10

    In this research, based on an analytical expression for cross-spectral density (CSD) matrix elements, coherence and polarization properties of phase-locked partially coherent flat-topped (PCFT) radial array laser beams propagating through weak oceanic turbulence are analyzed. Spectral degrees of coherence and polarization are analytically calculated using CSD matrix elements. Also, the effective width of spatial degree of coherence (EWSDC) is calculated numerically. The simulation is done by considering the effects of source parameters (such as radius of the array setup's circle, effective width of the spectral degree of coherence, and wavelength) and turbulent ocean factors (such as the rate of dissipation of the turbulent kinetic energy per unit mass of fluid and relative strength of temperature and salinity fluctuations, Kolmogorov micro-scale, and rate of dissipation of the mean squared temperature) in detail. Results indicate that any change in the amount of turbulence factors that increase the turbulence power reduces the EWSDC significantly and causes the reduction in the degree of polarization, and occurs at shorter propagation distances but with smaller magnitudes. In addition, being valid for all conditions, the degradation rate of the EWSDC of Gaussian array beams are more in comparison with the PCFT ones. The simulation and calculation results are shown by graphs.

  17. Evaluation of latent variances in Monte Carlo dose calculations with Varian TrueBeam photon phase-spaces used as a particle source

    Science.gov (United States)

    Alhakeem, Eyad; Zavgorodni, Sergei

    2018-01-01

    The purpose of this study was to evaluate the latent variance (LV) of Varian TrueBeam photon phase-space files (PSF) for open 10  ×  10 cm2 and small stereotactic fields and estimate the number of phase spaces required to be summed up in order to maintain sub-percent LV in Monte Carlo (MC) dose calculations. BEAMnrc/DOSXYZnrc software was used to transport particles from Varian phase-space files (PSFA) through the secondary collimators. Transported particles were scored into another phase-space located under the jaws (PSFB), or transported further through the cone collimators and scored straight below, forming PSFC. Phase-space files (PSFB) were scored for 6 MV-FFF, 6 MV, 10 MV-FFF, 10 MV and 15 MV beams with 10  ×  10 cm2 field size, and PSFC were scored for 6 MV beam under circular cones of 0.13, 0.25, 0.35, and 1 cm diameter. Both PSFB and PSFC were transported into a water phantom with particle recycling number ranging from 10 to 1000. For 10  ×  10 cm2 fields 0.5  ×  0.5  ×  0.5 cm3 voxels were used to score the dose, whereas the dose was scored in 0.1  ×  0.1  ×  0.5 cm3 voxels for beams collimated with small cones. In addition, for small 0.25 cm diameter cone-collimated 6 MV beam, phantom voxel size varied as 0.02  ×  0.02  ×  0.5 cm3, 0.05  ×  0.05  ×  0.5 cm3 and 0.1  ×  0.1  ×  0.5 cm3. Dose variances were scored in all cases and LV evaluated as per Sempau et al. For the 10  ×  10 cm2 fields calculated LVs were greatest at the phantom surface and decreased with depth until they reached a plateau at 5 cm depth. LVs were found to be 0.54%, 0.96%, 0.35%, 0.69% and 0.57% for the 6 MV-FFF, 6 MV, 10 MV-FFF, 10 MV and 15 MV energies, respectively at the depth of 10 cm. For the 6 MV phase-space collimated with cones of 0.13, 0.25, 0.35, 1.0 cm diameter, the LVs calculated at 1.5 cm depth were 75.6%, 25.4%, 17

  18. Message passing for quantified Boolean formulas

    International Nuclear Information System (INIS)

    Zhang, Pan; Ramezanpour, Abolfazl; Zecchina, Riccardo; Zdeborová, Lenka

    2012-01-01

    We introduce two types of message passing algorithms for quantified Boolean formulas (QBF). The first type is a message passing based heuristics that can prove unsatisfiability of the QBF by assigning the universal variables in such a way that the remaining formula is unsatisfiable. In the second type, we use message passing to guide branching heuristics of a Davis–Putnam–Logemann–Loveland (DPLL) complete solver. Numerical experiments show that on random QBFs our branching heuristics give robust exponential efficiency gain with respect to state-of-the-art solvers. We also manage to solve some previously unsolved benchmarks from the QBFLIB library. Apart from this, our study sheds light on using message passing in small systems and as subroutines in complete solvers

  19. How to pass higher English colour

    CERN Document Server

    Bridges, Ann

    2009-01-01

    How to Pass is the Number 1 revision series for Scottish qualifications across the three examination levels of Standard Grade, Intermediate and Higher! Second editions of the books present all of the material in full colour for the first time.

  20. Phase-space holes due to electron and ion beams accelerated by a current-driven potential ramp

    Directory of Open Access Journals (Sweden)

    M. V. Goldman

    2003-01-01

    Full Text Available One-dimensional open-boundary simulations have been carried out in a current-carrying plasma seeded with a neutral density depression and with no initial electric field. These simulations show the development of a variety of nonlinear localized electric field structures: double layers (unipolar localized fields, fast electron phase-space holes (bipolar fields moving in the direction of electrons accelerated by the double layer and trains of slow alternating electron and ion phase-space holes (wave-like fields moving in the direction of ions accelerated by the double layer. The principal new result in this paper is to show by means of a linear stability analysis that the slow-moving trains of electron and ion holes are likely to be the result of saturation via trapping of a kinetic-Buneman instability driven by the interaction of accelerated ions with unaccelerated electrons.

  1. Simulation of ion beam scattering in a gas stripper

    Energy Technology Data Exchange (ETDEWEB)

    Maxeiner, Sascha, E-mail: maxeiner@phys.ethz.ch; Suter, Martin; Christl, Marcus; Synal, Hans-Arno

    2015-10-15

    Ion beam scattering in the gas stripper of an accelerator mass spectrometer (AMS) enlarges the beam phase space and broadens its energy distribution. As the size of the injected beam depends on the acceleration voltage through phase space compression, the stripper becomes a limiting factor of the overall system transmission especially for low energy AMS system in the sub MV region. The spatial beam broadening and collisions with the accelerator tube walls are a possible source for machine background and energy loss fluctuations influence the mass resolution and thus isotope separation. To investigate the physical processes responsible for these effects, a computer simulation approach was chosen. Monte Carlo simulation methods are applied to simulate elastic two body scattering processes in screened Coulomb potentials in a (gas) stripper and formulas are derived to correctly determine random collision parameters and free path lengths for arbitrary (and non-homogeneous) gas densities. A simple parametric form for the underlying scattering cross sections is discussed which features important scaling behaviors. An implementation of the simulation was able to correctly model the data gained with the TANDY AMS system at ETH Zurich. The experiment covered transmission measurements of uranium ions in helium and beam profile measurements after the ion beam passed through the He-stripper. Beam profiles measured up to very high stripper densities could be understood in full system simulations including the relevant ion optics. The presented model therefore simulates the fundamental physics of the interaction between an ion beam and a gas stripper reliably. It provides a powerful and flexible tool for optimizing existing AMS stripper geometries and for designing new, state of the art low energy AMS systems.

  2. Improvement of Galilean refractive beam shaping system for accurately generating near-diffraction-limited flattop beam with arbitrary beam size.

    Science.gov (United States)

    Ma, Haotong; Liu, Zejin; Jiang, Pengzhi; Xu, Xiaojun; Du, Shaojun

    2011-07-04

    We propose and demonstrate the improvement of conventional Galilean refractive beam shaping system for accurately generating near-diffraction-limited flattop beam with arbitrary beam size. Based on the detailed study of the refractive beam shaping system, we found that the conventional Galilean beam shaper can only work well for the magnifying beam shaping. Taking the transformation of input beam with Gaussian irradiance distribution into target beam with high order Fermi-Dirac flattop profile as an example, the shaper can only work well at the condition that the size of input and target beam meets R(0) ≥ 1.3 w(0). For the improvement, the shaper is regarded as the combination of magnifying and demagnifying beam shaping system. The surface and phase distributions of the improved Galilean beam shaping system are derived based on Geometric and Fourier Optics. By using the improved Galilean beam shaper, the accurate transformation of input beam with Gaussian irradiance distribution into target beam with flattop irradiance distribution is realized. The irradiance distribution of the output beam is coincident with that of the target beam and the corresponding phase distribution is maintained. The propagation performance of the output beam is greatly improved. Studies of the influences of beam size and beam order on the improved Galilean beam shaping system show that restriction of beam size has been greatly reduced. This improvement can also be used to redistribute the input beam with complicated irradiance distribution into output beam with complicated irradiance distribution.

  3. A new concept for the control of a slow-extracted beam in a line with rotational optics, 2

    CERN Document Server

    Benedikt, Michael; Pullia, M

    1999-01-01

    For pt.I see ibid., vol.430, p.512-22, 1999. The current trend in hadron therapy is towards high-precision, conformal scanning of tumours with a `pencil' beam of light ions or protons, delivered by a synchrotron using slow extraction. The particular shape of the slow- extracted beam segment in phase space and the need to vary the beam size in a lattice with rotating optical elements create a special problem for the design of the extraction transfer line and gantry. The design concept presented in this report is based on telescope modules with integer- pi phase advances in both transverse planes. The beam size in the plane of the extraction is controlled by altering the phase advance and hence the rotation of the extracted beam segment in phase space. The vertical beam size is controlled by stepping the vertical betatron amplitude function over a range of values and passing the changed beam size from `hand-to-hand' through the telescope modules to the various treatment rooms. In the example given, a combined p...

  4. Message Passing Framework for Globally Interconnected Clusters

    International Nuclear Information System (INIS)

    Hafeez, M; Riaz, N; Asghar, S; Malik, U A; Rehman, A

    2011-01-01

    In prevailing technology trends it is apparent that the network requirements and technologies will advance in future. Therefore the need of High Performance Computing (HPC) based implementation for interconnecting clusters is comprehensible for scalability of clusters. Grid computing provides global infrastructure of interconnecting clusters consisting of dispersed computing resources over Internet. On the other hand the leading model for HPC programming is Message Passing Interface (MPI). As compared to Grid computing, MPI is better suited for solving most of the complex computational problems. MPI itself is restricted to a single cluster. It does not support message passing over the internet to use the computing resources of different clusters in an optimal way. We propose a model that provides message passing capabilities between parallel applications over the internet. The proposed model is based on Architecture for Java Universal Message Passing (A-JUMP) framework and Enterprise Service Bus (ESB) named as High Performance Computing Bus. The HPC Bus is built using ActiveMQ. HPC Bus is responsible for communication and message passing in an asynchronous manner. Asynchronous mode of communication offers an assurance for message delivery as well as a fault tolerance mechanism for message passing. The idea presented in this paper effectively utilizes wide-area intercluster networks. It also provides scheduling, dynamic resource discovery and allocation, and sub-clustering of resources for different jobs. Performance analysis and comparison study of the proposed framework with P2P-MPI are also presented in this paper.

  5. Test-beam evaluation of heavily irradiated silicon strip modules for ATLAS Phase-II Strip Tracker Upgrade

    CERN Document Server

    Blue, Andrew; The ATLAS collaboration

    2018-01-01

    The planned HL-LHC (High Luminosity LHC) is being designed to maximise the physics potential of the LHC with 10 years of operation at instantaneous luminosities of 7.5x1034cm−2s−1. A consequence of this increased luminosity is the expected radiation damage requiring the tracking detectors to withstand hadron equivalences to over 1x1015 1 MeV neutron equivalent per cm2 in the ATLAS Strips system. The silicon strip tracker exploits the concept of modularity. Fast readout electronics, deploying 130nm CMOS front-end electronics are glued on top of a silicon sensor to make a module. The radiation hard n-in-p micro-strip sensors used have been developed by the ATLAS ITk Strip Sensor collaboration and produced by Hamamatsu Photonics. A series of tests were performed at the DESY-II and CERN SPS test beam facilities to investigate the detailed performance of a strip module with both 2.5cm and 5cm length strips before and after irradiation with 8x1014neqcm−2 protons and a total ionising dose of 37.2MRad. The DURA...

  6. NOVOSIBIRSK/STANFORD: colliding linac beams

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    Plans to use colliding beams from linear accelerators are being considered at Novosibirsk and Stanford. The VLEPP scheme proposed for Novosibirsk and the Stanford single pass collider scheme are described. (W.D.L.).

  7. Beam-beam phenomenology

    International Nuclear Information System (INIS)

    Teng, L.C.

    1980-01-01

    In colliding beam storage rings the beam collision regions are generally so short that the beam-beam interaction can be considered as a series of evenly spaced non-linear kicks superimposed on otherwise stable linear oscillations. Most of the numerical studies on computers were carried out in just this manner. But for some reason this model has not been extensively employed in analytical studies. This is perhaps because all analytical work has so far been done by mathematicians pursuing general transcendental features of non-linear mechanics for whom this specific model of the specific system of colliding beams is too parochial and too repugnantly physical. Be that as it may, this model is of direct interest to accelerator physicists and is amenable to (1) further simplification, (2) physical approximation, and (3) solution by analogy to known phenomena

  8. Experimental evidence for multi-pass extraction with a bent crystal

    CERN Document Server

    Dehning, Bernd; Fidecaro, Giuseppe; Gyr, Marcel; Herr, Werner; Klem, J T; Scandale, Walter; Vuagnin, G; Weisse, E; Weisz, S; Møller, S P; Uggerhøj, Erik; Freund, A; Hustache, R; Carboni, G; Bussa, M P; Tosello, F

    1996-01-01

    The feasibility of extracting particles from the halo of a circulating proton beam using a bent silicon crystal has been demonstrated experimentally at the SPS for a beam energy of 120 GeV. Presently studies are conducted to understand the extraction mechanisms and the measured efficiencies. In particular the contribution of multi-pass extraction, where the particles can pass through the crystal many times before being channelled and extracted, is investigated. In a recent experiment, using a crystal especially fabricated with a finite amorphous layer on its surface, it has been proven that multi-pass extraction plays an important role. The experiment is described and the implication for further studies are discussed.

  9. A Phase I study of capecitabine, carboplatin, and paclitaxel with external beam radiation therapy for esophageal carcinoma

    International Nuclear Information System (INIS)

    Czito, Brian G.; Kelsey, Chris R.; Hurwitz, Herbert I.; Willett, Chris G.; Morse, Michael A.; Blobe, Gerard C.; Fernando, Nishan H.; D'Amico, Thomas A.; Harpole, David H.; Honeycutt, Wanda R.N.; Yu Daohai; Bendell, Johanna C.

    2007-01-01

    Purpose: Concurrent chemotherapy and radiation therapy (RT) are used to treat patients with esophageal cancer. The optimal combination of chemotherapeutic agents with RT is undefined. We evaluated a combination of capecitabine, carboplatin, and paclitaxel with RT in a phase I study. Methods and Materials: Patients with squamous cell carcinoma or adenocarcinoma of the esophagus initially received capecitabine, carboplatin, and paclitaxel with RT (1.8 Gy daily to 50.4 Gy). After completion, patients were restaged and evaluated for surgery. Primary endpoints included determination of dose-limiting toxicities (DLT) and a recommended phase II dose, non-DLT, and preliminary radiographic and pathologic response rates. Results: Thirteen patients were enrolled (10 men, 3 women). All were evaluable for toxicity and efficacy. Two of 3 patients at dose level 1 (capecitabine 825 mg/m 2 twice daily on RT days, carboplatin area under the curve (AUC) 2 weekly, paclitaxel 60 mg/m 2 weekly) had DLT (both Grade 4 esophagitis). Of these 3, 2 underwent esophagectomy and had pathologic complete response (pCR). Ten patients were then enrolled at dose level -1 (capecitabine 600 mg/m 2 twice daily, carboplatin AUC 1.5, paclitaxel 45 mg/m 2 ). Overall, 3 of 10 patients at dose level -1 developed DLT (2 Grade 3 esophagitis, 1 Grade 3 hypotension). Esophagectomy was performed in 6 of 10 patients. All patients had pathologic downstaging and 2 of 6 had pCR. Conclusions: The maximally tolerated/recommended phase II doses were capecitabine 600 mg/m 2 twice daily, carboplatin AUC 1.5 weekly, and paclitaxel 45 mg/m 2 weekly with RT to 50.4 Gy. In our small study, this regimen appears active but is accompanied by significant toxicities, primarily esophagitis

  10. Strain at a semiconductor nanowire-substrate interface studied using geometric phase analysis, convergent beam electron diffraction and nanobeam diffraction

    DEFF Research Database (Denmark)

    Persson, Johan Mikael; Wagner, Jakob Birkedal; Dunin-Borkowski, Rafal E.

    2011-01-01

    Semiconductor nanowires have been studied using electron microscopy since the early days of nanowire growth, e.g. [1]. A common approach for analysing nanowires using transmission electron microscopy (TEM) involves removing them from their substrate and subsequently transferring them onto carbon...... with CBED and NBED [4,5] have shown a high degree of consistency. Strain has previously only been measured in nanowires removed from their substrate [6], or only using GPA [7]. The sample used for the present investigation was an InP nanowire grown on a Si substrate using metal organic vapor phase...

  11. Molecular beam epitaxy of GeTe-Sb{sub 2}Te{sub 3} phase change materials studied by X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Shayduk, Roman

    2010-05-20

    The integration of phase change materials into semiconductor heterostructures may lead to the development of a new generation of high density non-volatile phase change memories. Epitaxial phase change materials allow to study the detailed structural changes during the phase transition and to determine the scaling limits of the memory. This work is dedicated to the epitaxial growth of Ge-Sb-Te phase change alloys on GaSb(001). We deposit Ge-Sb-Te (GST) films on GaSb(001) substrates by means of molecular beam epitaxy (MBE). The film orientation and lattice constant evolution is determined in real time during growth using grazing incidence X-ray diffraction (GID). The nucleation stage of the growth is studied in situ using reflection high energy electron diffraction (RHEED). Four growth regimes of GST on GaSb(001) were observed: amorphous, polycrystalline, incubated epitaxial and direct epitaxial. Amorphous film grows for substrate temperatures below 100 C. For substrate temperatures in the range 100-160 C, the film grows in polycrystalline form. Incubated epitaxial growth is observed at temperatures from 180 to 210 C. This growth regime is characterized by an initial 0.6nm thick amorphous layer formation, which crystallizes epitaxially as the film thickness increases. The determined lattice constant of the films is 6.01 A, very close to that of the metastable GST phase. The films predominantly possess an epitaxial cube-on-cube relationship. At higher temperatures the films grow epitaxially, however the growth rate is rapidly decreasing with temperature. At temperatures above 270 C the growth rate is zero. The composition of the grown films is close to 2:2:5 for Ge, Sb and Te, respectively. The determined crystal structure of the films is face centered cubic (FCC) with a rhombohedral distortion. The analysis of X-ray peak widths gives a value for the rhombohedral angle of 89.56 . We observe two types of reflections in reciprocal space indicating two FCC sublattices in

  12. Proposal for a Full-Scale Prototype Single-Phase Liquid Argon Time Projection Chamber and Detector Beam Test at CERN

    CERN Document Server

    Kutter, T

    2015-01-01

    The Deep Underground Neutrino Experiment (DUNE) will use a large liquid argon (LAr) detector to measure the CP violating phase, determine the neutrino mass hier- archy and perform precision tests of the three-flavor paradigm in long-baseline neutrino oscillations. The detector will consist of four modules each with a fiducial mass of 10 kt of LAr and due to its unprecedented size will allow sensitive searches for proton decay and the detection and measurement of electron neutrinos from core collapse supernovae [1]. The first 10 kt module will use single-phase LAr detection technique and be itself modular in design. The successful manufacturing, installation and operation of several full-scale detector components in a suitable configuration represents a critical engineering milestone prior to the construction and operation of the first full 10 kt DUNE detector module at the SURF underground site. A charged particle beam test of a prototype detector will provide critical calibration measurements as well as inva...

  13. Electrical performance of phase change memory cells with Ge{sub 3}Sb{sub 2}Te{sub 6} deposited by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Boschker, Jos E.; Riechert, Henning; Calarco, Raffaella [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany); Boniardi, Mattia; Redaelli, Andrea [Micron Semiconductor Italia S.r.l., Via C. Olivetti, 2, 20864, Agrate Brianza, MB (Italy)

    2015-01-12

    Here, we report on the electrical characterization of phase change memory cells containing a Ge{sub 3}Sb{sub 2}Te{sub 6} (GST) alloy grown in its crystalline form by Molecular Beam Epitaxy (MBE). It is found that the high temperature growth on the amorphous substrate results in a polycrystalline film exhibiting a rough surface with a grain size of approximately 80–150 nm. A detailed electrical characterization has been performed, including I-V characteristic curves, programming curves, set operation performance, crystallization activation at low temperature, and resistance drift, in order to determine the material related parameters. The results indicate very good alignment of the electrical parameters with the current state-of-the-art GST, deposited by physical vapor deposition. Such alignment enables a possible employment of the MBE deposition technique for chalcogenide materials in the phase change memory technology, thus leading to future studies of as-deposited crystalline chalcogenides as integrated in electrical vehicles.

  14. Performance evaluation of a drag-disc turbine transducer and three-beam gamma densitometer under transient two-phase flow conditions

    International Nuclear Information System (INIS)

    Nalezny, C.L.; Chen, L.L.; Solbrig, C.W.

    1979-01-01

    One of the primary variables measured in the Loss-of-Fluid Test (LOFT) Program is mass flow rate. LOFT uses drag-disc turbine tranducers (DTT) and a three-beam gamma densitometer to measure parameters from which mass flow may be computed. The transducer combination was performance tested under transient conditions in the blowdown loop at the LOFT Test Support Facility (LTSF). The performance tests consisted of three partial blowdowns of different durations starting from the same initial conditions. The reference mean mass flow rate was determined by measuring the amount of water required to reestablish initial conditions after each partial blowdown. The average mass flow rates computed from the output of the drag disc, turbine, and gamma densitometer were compared to the reference mean mass flow rates over three blowdown intervals. The tests indicated that the equal phase velocity mass measurement model provided excellent results through the use of the turbine and densitometer, and drag disc and densitometer when the phase velocities were nearly equal

  15. Initial stages of ion beam-induced phase transformations in Gd2O3 and Lu2O3

    Science.gov (United States)

    Chen, Chien-Hung; Tracy, Cameron L.; Wang, Chenxu; Lang, Maik; Ewing, Rodney C.

    2018-02-01

    The atomic-scale evolution of lanthanide sesquioxides Gd2O3 and Lu2O3 irradiated with 1 MeV Kr ions at room temperature and 120 K, up to fluences of 1 × 1016 ions/cm2 (˜20 dpa), has been characterized by in situ transmission electron microscopy. At room temperature, both oxides exhibited high radiation tolerance. Irradiation did not cause any observable structural change in either material, likely due to the mobility of irradiation-induced point defects, causing efficient defect annihilation. For Gd2O3, having the larger cation ionic radius of the two materials, an irradiation-induced stacking fault structure appeared at low fluences in the low temperature irradiation. As compared with the cubic-to-monoclinic phase transformations known to result from higher energy (˜GeV) ion irradiation, Kr ions of lower energies (˜MeV) yield much lower rates of damage accumulation and thus less extensive structural modification. At a fluence of 2.5 × 1015 ions/cm2, only the initial stages of the cubic-to-monoclinic (C to B) phase transformation process, consisting of the formation and aggregation of defects, have been observed.

  16. Beam breakup in a microtron

    International Nuclear Information System (INIS)

    Yung, B.C.; Merminga, L.

    1997-01-01

    In a microtron, the path length change from pass to pass is a fixed multiple of the RF wavelength, and the accelerating system can be reasonably well approximated as a single cavity. Under such circumstances it is possible to derive an analytical formula for the multipass beam breakup threshold current. The threshold current determined by numerical simulations agrees very well with the formula for a machine with a small number of passes. The analytic formula can serve as a useful guide in examining optics designs to improve the BBU threshold

  17. Two kinds of Airy-related beams

    International Nuclear Information System (INIS)

    Xu, Yiqing; Zhou, Guoquan; Zhang, Lijun; Ru, Guoyun

    2015-01-01

    Two kinds of Airy-related beams are introduced in this manuscript. The normalized intensity distribution in the x-direction of the two kinds of Airy-related beams is close to that of the Gaussian beam. The normalized intensity distribution in the y-direction of the two kinds of Airy-related beams is close to that of the second-order and the third-order elegant Hermite–Gaussian beams, respectively. Analytical expressions of the two kinds of Airy-related beams passing through an ABCD paraxial optical system are derived. The beam propagation factors for the two kinds of Airy-related beams are 1.933 and 2.125, respectively. Analytical expressions of the beam half widths and the kurtosis parameters of the two kinds of Airy-related beams passing through an ABCD paraxial optical system are also presented. As a numerical example, the propagation properties of the two kinds of Airy-related beams are demonstrated in free space. Moreover, the comparison between the two kinds of Airy-related beams and their corresponding elegant Hermite–Gaussian beams along the two transverse directions are performed in detail. Upon propagation, the former kind of Airy-related beam will evolve from the central bright beam into the dark hollow beam. Contrarily, the latter kind of Airy-related beam will evolve from the dark hollow beam into the central bright beam. These two kinds of Airy-related beams can be used to describe specially distributed beams. (paper)

  18. A study of the solid-phase thermal decomposition of NTO using simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS)

    Energy Technology Data Exchange (ETDEWEB)

    Minier, L.; Behrens, R. [Sandia National Labs., Livermore, CA (United States). Combustion Research Facility; Burkey, T.J. [Univ. of Memphis, TN (United States). Chemistry Dept.

    1997-01-01

    The solid phase thermal reaction chemistry of NTO between 190 and 250 C is presently being evaluated by utilizing STMBMS, a technique that enables the authors to measure the vapor pressure of NTO and to explore the reaction mechanisms and chemical kinetics associated with the NTO thermal decomposition process. The vapor pressure of NTO is expressed as Log{sub 10} p(torr) = 12.5137 + 6,296.553(1/t{sub k}) and the {Delta}H{sub subl} = 28.71 {+-} 0.07 kcal/mol (120.01 {+-} 0.29 kJ/mol). The pyrolysis of NTO results in the formation of gaseous products and a condensed-phase residue. The identity of the major gaseous products and their origin from within the NTO molecules are determined based on the results from pyrolysis of NTO, NTO-3-{sup 13}C, NTO-1,2-{sup 15}N{sub 2} and NTO-{sup 2}H{sub 2}. Identification of the products show the major gaseous products to be N{sub 2}, CO{sub 2}, NO, HNCO, H{sub 2}O and some N{sub 2}O, CO, HCN and NH{sub 3}. The N{sub 2} is mostly derived from the N-1 and N-2 positions with some being from the N-4 and N-1 or N-2 positions. The CO{sub 2} is derived from both carbons in the NTO molecule in comparable amounts. The residue has an elemental formula of C{sub 2.1}H{sub .26}N{sub 2.9}O and FTIR analysis suggests that the residue is polyurea- and polycarbamate-like in nature. The temporal behaviors of the rates of formation of the gaseous products indicate that the overall thermal decomposition of NTO in the temperature range evaluated involves four major processes: (1) NTO sublimation; (2) an apparent solid-solid phase transition between 190 and 195 C; (3) a decomposition regime induced by the presence of exogenous H{sub 2}O at the onset of decomposition; and (4) a decomposition regime that occurs at the onset of decomposition and continues until the depletion of NTO. Decomposition pathways that are consistent with the data are presented.

  19. Low-dose cardio-respiratory phase-correlated cone-beam micro-CT of small animals.

    Science.gov (United States)

    Sawall, Stefan; Bergner, Frank; Lapp, Robert; Mronz, Markus; Karolczak, Marek; Hess, Andreas; Kachelriess, Marc

    2011-03-01

    Micro-CT imaging of animal hearts typically requires a double gating procedure because scans during a breath-hold are not possible due to the long scan times and the high respiratory rates, Simultaneous respiratory and cardiac gating can either be done prospectively or retrospectively. True five-dimensional information can be either retrieved with retrospective gating or with prospective gating if several prospective gates are acquired. In any case, the amount of information available to reconstruct one volume for a given respiratory and cardiac phase is orders of magnitud lower than the total amount of information acquired. For example, the reconstruction of a volume from a 10% wide respiratory and a 20% wide cardiac window uses only 2% of the data acquired. Achieving a similar image quality as a nongated scan would therefore require to increase the amount of data and thereby the dose to the animal by up to a factor of 50. To achieve the goal of low-dose phase-correlated (LDPC) imaging, the authors propose to use a highly efficient combination of slightly modified existing algorithms. In particular, the authors developed a variant of the McKinnon-Bates image reconstruction algorithm and combined it with bilateral filtering in up to five dimensions to significantly reduce image noise without impairing spatial or temporal resolution. The preliminary results indicate that the proposed LDPC reconstruction method typically reduces image noise by a factor of up to 6 (e.g., from 170 to 30 HU), while the dose values lie in a range from 60 to 500 mGy. Compared to other publications that apply 250-1800 mGy for the same task [C. T. Badea et al., "4D micro-CT of the mouse heart," Mol. Imaging 4(2), 110-116 (2005); M. Drangova et al., "Fast retrospectively gated quantitative four-dimensional (4D) cardiac micro computed tomography imaging of free-breathing mice," Invest. Radiol. 42(2), 85-94 (2007); S. H. Bartling et al., "Retrospective motion gating in small animal CT of mice

  20. Integrated Cu-based TM-pass polarizer using CMOS technology platform

    KAUST Repository

    Ng, Tien Khee

    2010-01-01

    A transverse-magnetic-pass (TM-pass) copper (Cu) polarizer is proposed and analyzed using the previously published two-dimensional Method-of-Lines beam-propagation model. The proposed polarizer exhibits a simulated high-pass filter characteristics, with TM0 and TE0 mode transmissivity of >70% and <5%, respectively, in the wavelength regime of 1.2-1.6 μm. The polarization extinction ratio (PER) given by 10 log10 (PTM0)/(PTE0) is +11.5 dB across the high-pass wavelength regime. To the best of the authors\\' knowledge, we report here the smallest footprint CMOS-platform compatible TM-polarizer.

  1. Static thermo-optic instability in double-pass fiber amplifiers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2016-01-01

    A coupled-mode formalism, earlier used to describe transverse mode instabilities in single-pass optical fiber amplifiers, is extended to the case of double-pass amplifiers. Contrary to the single-pass case, it is shown that the thermo-optic nonlinearity can couple light at the same frequency...... between the LP01 and LP11 modes, leading to a static deformation of the output beam profile. This novel phenomenon is caused by the interaction of light propagating in either direction with thermo-optic index perturbations caused by light propagating in the opposite direction. The threshold power...... for the static deformation is found to be several times lower than what is typically found for the dynamic modal instabilities observed in single-pass amplifiers. (C) 2016 Optical Society of America...

  2. Consideration of Wall Reflection and Diffraction in the Room Acoustic Prediction Using the Phased Beam Tracing Method

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2007-01-01

    of the applicability of the geometrical methods to mid frequency. Several studies on this method have demonstrated a good possibility to analyze the sound field in an enclosure at mid frequency. In this study, further considerations on wall reflection and diffraction have been investigated. The main suggestions...... of representing the negative real part was discussed. The PBTM result shows a good agreement with the measurement especially in the early part of impulse response and at mid frequency. The new method of ii binaural simulation for the PBTM was suggested. The peculiar feature of frequency domain calculation......The geometrical acoustics methods have been used to simulate the acoustics of rooms at high frequencies whereas the wave based methods have been devoted to calculate the low frequency response. The modified method, so called phased geometrical acoustics technique, was suggested for the extension...

  3. A Phase 1/2 and Biomarker Study of Preoperative Short Course Chemoradiation With Proton Beam Therapy and Capecitabine Followed By Early Surgery for Resectable Pancreatic Ductal Adenocarcinoma

    International Nuclear Information System (INIS)

    Hong, Theodore S.; Ryan, David P.; Borger, Darrell R.; Blaszkowsky, Lawrence S.; Yeap, Beow Y.; Ancukiewicz, Marek; Deshpande, Vikram; Shinagare, Shweta; Wo, Jennifer Y.; Boucher, Yves; Wadlow, Raymond C.; Kwak, Eunice L.; Allen, Jill N.; Clark, Jeffrey W.; Zhu, Andrew X.; Ferrone, Cristina R.; Mamon, Harvey J.; Adams, Judith; Winrich, Barbara; Grillo, Tarin

    2014-01-01

    Purpose: To evaluate the safety, efficacy and biomarkers of short-course proton beam radiation and capecitabine, followed by pancreaticoduodenectomy in a phase 1/2 study in pancreatic ductal adenocarcinoma (PDAC) patients. Methods and Materials: Patients with radiographically resectable, biopsy-proven PDAC were treated with neoadjuvant short-course (2-week) proton-based radiation with capecitabine, followed by surgery and adjuvant gemcitabine. The primary objective was to demonstrate a rate of toxicity grade ≥3 of <20%. Exploratory biomarker studies were performed using surgical specimen tissues and peripheral blood. Results: The phase 2 dose was established at 5 daily doses of 5 GyE. Fifty patients were enrolled, of whom 35 patients were treated in the phase 2 portion. There were no grade 4 or 5 toxicities, and only 2 of 35 patients (4.1%) experienced a grade 3 toxicity event (chest wall pain grade 1, colitis grade 1). Of 48 patients eligible for analysis, 37 underwent pancreaticoduodenectomy. Thirty of 37 (81%) had positive nodes. Locoregional failure occurred in 6 of 37 resected patients (16.2%), and distant recurrence occurred in 35 of 48 patients (72.9%). With median follow-up of 38 months, the median progression-free survival for the entire group was 10 months, and overall survival was 17 months. Biomarker studies showed significant associations between worse survival outcomes and the KRAS point mutation change from glycine to aspartic acid at position 12, stromal CXCR7 expression, and circulating biomarkers CEA, CA19-9, and HGF (all, P<.05). Conclusions: This study met the primary endpoint by showing a rate of 4.1% grade 3 toxicity for neoadjuvant short-course proton-based chemoradiation. Treatment was associated with favorable local control. In exploratory analyses, KRAS G12D status and high CXCR7 expression and circulating CEA, CA19-9, and HGF levels were associated with poor survival

  4. Instantaneous phase-shifting Fizeau interferometry with high-speed pixelated phase-mask camera

    Science.gov (United States)

    Yatagai, Toyohiko; Jackin, Boaz Jessie; Ono, Akira; Kiyohara, Kosuke; Noguchi, Masato; Yoshii, Minoru; Kiyohara, Motosuke; Niwa, Hayato; Ikuo, Kazuyuki; Onuma, Takashi

    2015-08-01

    A Fizeou interferometer with instantaneous phase-shifting ability using a Wollaston prism is designed. to measure dynamic phase change of objects, a high-speed video camera of 10-5s of shutter speed is used with a pixelated phase-mask of 1024 × 1024 elements. The light source used is a laser of wavelength 532 nm which is split into orthogonal polarization states by passing through a Wollaston prism. By adjusting the tilt of the reference surface it is possible to make the reference and object beam with orthogonal polarizations states to coincide and interfere. Then the pixelated phase-mask camera calculate the phase changes and hence the optical path length difference. Vibration of speakers and turbulence of air flow were successfully measured in 7,000 frames/sec.

  5. Charge-equilibrium and radiation of low-energy cosmic rays passing through interstellar medium

    Science.gov (United States)

    Rule, D. W.; Omidvar, K.

    1977-01-01

    The charge equilibrium and radiation of an oxygen and an iron beam in the MeV per nucleon energy range, representing a typical beam of low-energy cosmic rays passing through the interstellar medium, is considered. Electron loss of the beam has been taken into account by means of the First Born approximation allowing for the target atom to remain unexcited, or to be excited to all possible states. Electron capture cross sections have been calculated by means of the scaled Oppenheimer-Brinkman-Kramers approximation, taking into account all atomic shells of the target atoms. Radiation of the beam due to electron capture into the excited states of the ion, collisional excitation and collisional inner-shell ionization of the ions has been considered. Effective X-ray production cross sections and multiplicities for the most energetic X-ray lines emitted by the Fe and O beams have been calculated.

  6. INVESTIGATION OF SINGLE-PASS/DOUBLE-PASS TECHNIQUES ON FRICTION STIR WELDING OF ALUMINIUM

    Directory of Open Access Journals (Sweden)

    N.A.A. Sathari

    2014-12-01

    Full Text Available The aim of this research is to study the effects of single-pass/ double-pass techniques on friction stir welding of aluminium. Two pieces of AA1100 with a thickness of 6.0 mm were friction stir welded using a CNC milling machine at rotational speeds of 1400 rpm, 1600 rpm and 1800 rpm respectively for single-pass and double-pass. Microstructure observations of the welded area were studied using an optical microscope. The specimens were tested by using a tensile test and Vickers hardness test to evaluate their mechanical properties. The results indicated that, at low rotational speed, defects such as ‘surface lack of fill’ and tunnels in the welded area contributed to a decrease in mechanical properties. Welded specimens using double-pass techniques show increasing values of tensile strength and hardness. From this investigation it is found that the best parameters of FSW welded aluminium AA1100 plate were those using double-pass techniques that produce mechanically sound joints with a hardness of 56.38 HV and 108 MPa strength at 1800 rpm compared to the single-pass technique. Friction stir welding, single-pass/ double-pass techniques, AA1100, microstructure, mechanical properties.

  7. Range shortening, radiation transport, and Rayleigh-Taylor instability phenomena in ion-beam-driven inertial-fusion-reactor-size targets: Implosion, ignition, and burn phases

    International Nuclear Information System (INIS)

    Long, K.A.; Tahir, N.A.

    1987-01-01

    In this paper we present an analysis of the theory of the energy deposition of ions in cold materials and hot dense plasmas together with numerical calculations for heavy and light ions of interest to ion-beam fusion. We have used the gorgon computer code of Long, Moritz, and Tahir (which is an extension of the code originally written for protons by Nardi, Peleg, and Zinamon) to carry out these calculations. The energy-deposition data calculated in this manner has been used in the design of heavy-ion-beam-driven fusion targets suitable for a reactor, by its inclusion in the medusa code of Christiansen, Ashby, and Roberts as extended by Tahir and Long. A number of other improvements have been made in this code and these are also discussed. Various aspects of the theoretical analysis of such targets are discussed including the calculation of the hydrodynamic stability, the hydrodynamic efficiency, and the gain. Various different target designs have been used, some of them new. In general these targets are driven by Bi + ions of energy 8--12 GeV, with an input energy of 4--6.5 MJ, with output energies in the range 600--900 MJ, and with gains in the range 120--180. The peak powers are in the range of 500--750 TW. We present detailed calculations of the ablation, compression, ignition, and burn phases. By the application of a new stability analysis which includes ablation and density-gradient effects we show that these targets appear to implode in a stable manner. Thus the targets designed offer working examples suited for use in a future inertial-confinement fusion reactor

  8. A recycling molecular beam reactor

    International Nuclear Information System (INIS)

    Prada-Silva, G.; Haller, G.L.; Fenn, J.B.

    1974-01-01

    In a Recycling Molecular Beam Reactor, RMBR, a beam of reactant gas molecules is formed from a supersonic free jet. After collision with a target the molecules pass through the vacuum pumps and are returned to the nozzle source. Continuous recycling permits the integration of very small reaction probabilities into measurable conversions which can be analyzed by gas chromatography. Some preliminary experiments have been carried out on the isomerization of cyclopropane

  9. Intraoperative boron neutron capture therapy for malignant gliomas. First clinical results of Tsukuba phase I/II trial using JAERI mixed thermal-epithermal beam

    International Nuclear Information System (INIS)

    Matsumura, A.; Yamamoto, T.; Shibata, Y.

    2000-01-01

    Since October 1999, a clinical trial of intraoperative boron neutron capture therapy (IOBNCT) is in progress at JRR-4 (Japan Research Reactor-4) in Japan Atomic Energy Research Institute (JAERI) using mixed thermal-epithermal beam (thermal neutron beam I: TNB-I). Compared to pure thermal beam (thermal neutron beam II: TNB-II), TNB-I has an improved neutron delivery into the deep region than TNB-II. The clinical protocol and the preliminary results will be discussed. (author)

  10. Beam propagation

    International Nuclear Information System (INIS)

    Hermansson, B.R.

    1989-01-01

    The main part of this thesis consists of 15 published papers, in which the numerical Beam Propagating Method (BPM) is investigated, verified and used in a number of applications. In the introduction a derivation of the nonlinear Schroedinger equation is presented to connect the beginning of the soliton papers with Maxwell's equations including a nonlinear polarization. This thesis focuses on the wide use of the BPM for numerical simulations of propagating light and particle beams through different types of structures such as waveguides, fibers, tapers, Y-junctions, laser arrays and crystalline solids. We verify the BPM in the above listed problems against other numerical methods for example the Finite-element Method, perturbation methods and Runge-Kutta integration. Further, the BPM is shown to be a simple and effective way to numerically set up the Green's function in matrix form for periodic structures. The Green's function matrix can then be diagonalized with matrix methods yielding the eigensolutions of the structure. The BPM inherent transverse periodicity can be untied, if desired, by for example including an absorptive refractive index at the computational window edges. The interaction of two first-order soliton pulses is strongly dependent on the phase relationship between the individual solitons. When optical phase shift keying is used in coherent one-carrier wavelength communication, the fiber attenuation will suppress or delay the nonlinear instability. (orig.)

  11. Multipass autogenous electron beam welding

    International Nuclear Information System (INIS)

    Murphy, J.L.; Mustaleski, T.M. Jr.; Watson, L.C.

    1986-01-01

    A multipass, autogenous welding procedure was developed for 7.6 mm (0.3 in.) wall thickness Type 304L stainless steel cylinders. The joint geometry has a 1.5 mm (0.06 in.) root-face width and a rectangular stepped groove that is 0.762 mm (0.03 in.) wide at the top of the root face and extends 1.5 mm in height, terminating into a groove width of 1.27 mm which extends to the outside of the 1.27 mm high weld-boss. One weld pass is made on the root, three passes on the 0.762 mm wide groove and three passes to complete the weld. Multipass, autogenous, electron beam welds maintain the characteristic high depth-to-width ratios and low heat input of single-pass, electron beam welds. The increased part distortion (which is still much less than from arc processes) in multipass weldments is corrected by a preweld machined compensation. Mechanical properties of multipass welds compare well with single-pass welds. The yield strength of welds in aluminum alloy 5083 is approximately the same for single-pass or multipass electron beam and gas, metal-arc welds. The incidence and size of porosity is less in multipass electron beam welding of aluminum as compared to gas, metal-arc welds. The multipass, autogenous, electron beam welding method has proven to be a reliable way to make some difficult welds in multilayer parts or in an instance where inside part temperature or weld underbead must be controlled and weld discontinuities must be minimized

  12. Setting pass scores for clinical skills assessment.

    Science.gov (United States)

    Liu, Min; Liu, Keh-Min

    2008-12-01

    In a clinical skills assessment, the decision to pass or fail an examinee should be based on the test content or on the examinees' performance. The process of deciding a pass score is known as setting a standard of the examination. This requires a properly selected panel of expert judges and a suitable standard setting method, which best fits the purpose of the examination. Six standard setting methods that are often used in clinical skills assessment are described to provide an overview of the standard setting process.

  13. Setting Pass Scores for Clinical Skills Assessment

    Directory of Open Access Journals (Sweden)

    Min Liu

    2008-12-01

    Full Text Available In a clinical skills assessment, the decision to pass or fail an examinee should be based on the test content or on the examinees' performance. The process of deciding a pass score is known as setting a standard of the examination. This requires a properly selected panel of expert judges and a suitable standard setting method, which best fits the purpose of the examination. Six standard setting methods that are often used in clinical skills assessment are described to provide an overview of the standard setting process.

  14. Ultrastructural evaluation of multiple pass low energy versus single pass high energy radio-frequency treatment.

    Science.gov (United States)

    Kist, David; Burns, A Jay; Sanner, Roth; Counters, Jeff; Zelickson, Brian

    2006-02-01

    The radio-frequency (RF) device is a system capable of volumetric heating of the mid to deep dermis and selective heating of the fibrous septa strands and fascia layer. Clinically, these effects promote dermal collagen production, and tightening of these deep subcutaneous structures. A new technique of using multiple low energy passes has been described which results in lower patient discomfort and fewer side effects. This technique has also been anecdotally described as giving more reproducible and reliable clinical results of tissue tightening and contouring. This study will compare ultrastructural changes in collagen between a single pass high energy versus up to five passes of a multiple pass lower energy treatment. Three subjects were consented and treated in the preauricular region with the RF device using single or multiple passes (three or five) in the same 1.5 cm(2) treatment area with a slight delay between passes to allow tissue cooling. Biopsies from each treatment region and a control biopsy were taken immediately, 24 hours or 6 months post treatment for electron microscopic examination of the 0-1 mm and 1-2 mm levels. Sections of tissue 1 mm x 1 mm x 80 nm were examined with an RCA EMU-4 Transmission Electron Microscope. Twenty sections from 6 blocks from each 1 mm depth were examined by 2 blinded observers. The morphology and degree of collagen change in relation to area examined was compared to the control tissue, and estimated using a quantitative scale. Ultrastructural examination of tissue showed that an increased amount of collagen fibril changes with increasing passes at energies of 97 J (three passes) and 122 J (five passes), respectively. The changes seen after five multiple passes were similar to those detected after much more painful single pass high-energy treatments. This ultrastructural study shows changes in collagen fibril morphology with an increased effect demonstrated at greater depths of the skin with multiple low-fluence passes

  15. Study of the scheme of two-beam accelerator driver with accompanying electromagnetic wave

    International Nuclear Information System (INIS)

    Elzhov, A.V.; Kaminskij, A.K.; Kazacha, V.I.; Perel'shtejn, E.A.; Sedykh, S.N.; Sergeev, A.P.

    2000-01-01

    A novel scheme of two-beam accelerator (TBA) driver based on a linear induction accelerator is considered. In this scheme the bunched beam propagates in the accompanying enhanced microwave that provides the steady longitudinal beam bunching along the whole driver. A travelling wave tube (TWT) is used as the wave-slowing periodic structure. Major merits of the driver scheme in hand are the possibilities of providing the microwave phase and amplitude stability and the preliminary beam bunching at a rather low initial energy (∼ 1 MeV). The numerical simulation has shown that a steady state could be found when electron bunches accompanied by an amplified microwave are simultaneously accelerated in the external electric field. The total power, which is inserted into the beam by the accelerating field, transforms into the microwave power in the steady state. The first set of experiments was fulfilled with the buncher on the base of the JINR LIU-3000 linac (electron beam energy ∼ 600 keV, electron current ∼ 150 A). The considerable level of the amplified microwave power (∼ 5 MW) and high enough bunching parameter (∼ 0.4) were obtained. The electron beam bunching at the frequency of 36.4 GHz was registered by means of the Cherenkov radiation of the electron bunches that occurred at their passing through the special target. The beam keeps a high bunching level at the distance ∼ 10 cm from the TWT exit being accompanied by the amplified microwave

  16. Determination of the polarization states of an arbitrary polarized terahertz beam: vectorial vortex analysis.

    Science.gov (United States)

    Wakayama, Toshitaka; Higashiguchi, Takeshi; Oikawa, Hiroki; Sakaue, Kazuyuki; Washio, Masakazu; Yonemura, Motoki; Yoshizawa, Toru; Tyo, J Scott; Otani, Yukitoshi

    2015-03-24

    Vectorial vortex analysis is used to determine the polarization states of an arbitrarily polarized terahertz (0.1-1.6 THz) beam using THz achromatic axially symmetric wave (TAS) plates, which have a phase retardance of Δ = 163° and are made of polytetrafluorethylene. Polarized THz beams are converted into THz vectorial vortex beams with no spatial or wavelength dispersion, and the unknown polarization states of the incident THz beams are reconstructed. The polarization determination is also demonstrated at frequencies of 0.16 and 0.36 THz. The results obtained by solving the inverse source problem agree with the values used in the experiments. This vectorial vortex analysis enables a determination of the polarization states of the incident THz beam from the THz image. The polarization states of the beams are estimated after they pass through the TAS plates. The results validate this new approach to polarization detection for intense THz sources. It could find application in such cutting edge areas of physics as nonlinear THz photonics and plasmon excitation, because TAS plates not only instantaneously elucidate the polarization of an enclosed THz beam but can also passively control THz vectorial vortex beams.

  17. High frequency fishbone driven by passing energetic ions in tokamak plasmas

    Science.gov (United States)

    Wang, Feng; Yu, L. M.; Fu, G. Y.; Shen, Wei

    2017-05-01

    High frequency fishbone instability driven by passing energetic ions was first reported in the Princeton beta experiment with tangential neutral-beam-injection (Heidbrink et al 1986 Phys. Rev. Lett. 57 835-8). It could play an important role for ITER-like burning plasmas, where α particles are mostly passing particles. In this work, a generalized energetic ion distribution function and finite drift orbit width effect are considered to improve the theoretical model for passing particle driving fishbone instability. For purely passing energetic ions with zero drift orbit width, the kinetic energy δ {{W}k} is derived analytically. The derived analytic expression is more accurate as compared to the result of previous work (Wang 2001 Phys. Rev. Lett. 86 5286-8). For a generalized energetic ion distribution function, the fishbone dispersion relation is derived and is solved numerically. Numerical results show that broad and off-axis beam density profiles can significantly increase the beam ion beta threshold {βc} for instability and decrease mode frequency.

  18. High-power Bessel beams with orbital angular momentum in the terahertz range

    Science.gov (United States)

    Choporova, Yu. Yu.; Knyazev, B. A.; Kulipanov, G. N.; Pavelyev, V. S.; Scheglov, M. A.; Vinokurov, N. A.; Volodkin, B. O.; Zhabin, V. N.

    2017-08-01

    In this paper, we have performed experimental, analytical, and numerical studies of beams with topological charges of ±1 and ±2 formed by silicon binary phase axicons (BPAs) with spiral zone structures. The axicons were illuminated with the Novosibirsk free electron laser radiation (a continuous stream of 100-ps pulses at f =5.6 MHz). The cw power of the beams produced reached 30 W and can by doubled via antireflection coating of the axicons. The intensity distribution in the beam cross sections was in good agreement with the Bessel functions and was kept constant within a distance of about L /r ≈190 and 100, where the first ring radii of the beams r were 0.9 and 1.5 mm for the Bessel beams of the first and second orders, respectively. Although the characteristics of the beams (Bessel cross section, "diffraction-free" propagation, self-recovery after passing obstacles, and randomly inhomogeneous media) corresponded to the properties of ideal Bessel beams, their spatial Fourier spectrum (the image in the focal plane of the lens) was, instead of an ideal ring, intertwined segments of arcs with phases shifted by π , the number of which was equal to the double value of the topological charge. This feature can be used, for example, in a demultiplexing unit of a free vortex-wave communication system or for identification of beam topological charge. We also revisited Young's double-slit diffraction and rotation of beams obstructed by a half-plane, previously applied to Laguerre-Gaussian beam characterization, in the case of the Bessel beams. The Young diffraction pattern demonstrated in this case a complicated intensity-phase distribution. It was shown that the Bessel beams formed by BPAs have two important advantages, which can be used in applications, in comparison with other methods of generation, e.g., a combination of an axicon lens with a spiral phase plate. Although the phase jumps of the axicons are designed for a determined wavelength (141 μ m in our case

  19. Focused Ion Beam Nanotomography of ruthenium-bearing nickel-base superalloys with focus on cast-microstructure and phase stability; Focused Ion Beam Nanotomographie von rutheniumhaltigen Nickelbasis-Superlegierungen mit Fokus auf Gussgefuege und Phasenstabilitaet

    Energy Technology Data Exchange (ETDEWEB)

    Cenanovic, Samir

    2012-12-03

    The influence of rhenium and ruthenium on the multi component system nickel-base superalloy is manifold and complex. An experimental nickel-base superalloy containing rhenium and ruthenium within defined contents, named Astra, was used to investigate the influences of these two elements on the alloy system. The last stage solidification of nickel-base superalloys after Bridgman casting and the high temperature phase stability of these alloys, could be explored with the aid of focused ion beam nanotomography. FIB-nt therefore was introduced and realized at the chair of General Materials Properties of the University Erlangen-Nuremberg. Cast Astra alloys are like other nickel-base superalloys morphologically very inhomogeneous and affected by segregation. In the interdendritic region different structures with huge γ' precipitates are formed. These inhomogeneities and remaining eutectics degrade the mechanical properties, witch makes an understanding of the subsiding processes at solidification of residual melt important for the casting process and the heat treatment. This is why the last stage solidification in the interdendritic region was analyzed. With the help of focused ion beam nanotomography, three different structures identified from 2-D sections could be assigned to one original 3-D structure. It was pointed out, that only the orientation of the plane of the 2-D cut influences the appearance in the 2-D section. The tomography information was used to explain the development during solidification and to create a model of last stage solidification. The interdendritic region is solidifying under the development of eutectic islands. The structure nucleates eutectically epitaxially at primary dendrite arms, with formation of fine γ/γ' precipitates. During solidification the γ' precipitates coarsen in a rod-like structure, and end up in large γ' precipitates. Simulations and other investigations could approve this model. First three

  20. Implementation and performance of beam smoothing on 10 beams of the Nova Laser

    International Nuclear Information System (INIS)

    Pennington, D.M.

    1997-01-01

    Recent simulations and experiments on Nova indicate that some level of smoothing may be required to suppress filamentation in plasmas on the National Ignition Facility (NIF), resulting in the addition of 1-D smoothing capability to the current baseline design. Control of stimulated Brillouin scattering (SBS) and filamentation is considered essential to the success of laser fusion because they affect the amount and location of laser energy delivered to the x-ray conversion region (hohlraum wall) for indirect drive and to the absorptive region for direct drive, Smoothing by spectral dispersion (SSD)[1], reduces these instabilities by reducing nonuniformities in the focal irradiance when averaged over a finite time interval. We have installed SSD on Nova to produce beam smoothing on all 10 beam lines. A single dispersion grating is located in a position common to all 10 beam lines early in the preamplifier chain. This location limits the 1 ω bandwidth to 2.2 (angstrom) with sufficient dispersion to displace the speckle field of each frequency component at the target plane by one half speckle diameter. Several beam lines were modified to allow orientation of the dispersion on each arm relative to the hohlraum wall. After conversion to the third harmonic the beam passes through a kinoform phase plate (KPP) designed to produce an elliptical spot at best focus. The KPPs produce a focal spot having an elliptical flat-top envelope with a superimposed speckle pattern. Over 93% of the energy is contained in the central 400 km. Calculations indicate a 16% rms. intensity variance will be reached after 330 ps for a single beam

  1. Statistics of Epidemics in Networks by Passing Messages

    Science.gov (United States)

    Shrestha, Munik Kumar

    Epidemic processes are common out-of-equilibrium phenomena of broad interdisciplinary interest. In this thesis, we show how message-passing approach can be a helpful tool for simulating epidemic models in disordered medium like networks, and in particular for estimating the probability that a given node will become infectious at a particular time. The sort of dynamics we consider are stochastic, where randomness can arise from the stochastic events or from the randomness of network structures. As in belief propagation, variables or messages in message-passing approach are defined on the directed edges of a network. However, unlike belief propagation, where the posterior distributions are updated according to Bayes' rule, in message-passing approach we write differential equations for the messages over time. It takes correlations between neighboring nodes into account while preventing causal signals from backtracking to their immediate source, and thus avoids "echo chamber effects" where a pair of adjacent nodes each amplify the probability that the other is infectious. In our first results, we develop a message-passing approach to threshold models of behavior popular in sociology. These are models, first proposed by Granovetter, where individuals have to hear about a trend or behavior from some number of neighbors before adopting it themselves. In thermodynamic limit of large random networks, we provide an exact analytic scheme while calculating the time dependence of the probabilities and thus learning about the whole dynamics of bootstrap percolation, which is a simple model known in statistical physics for exhibiting discontinuous phase transition. As an application, we apply a similar model to financial networks, studying when bankruptcies spread due to the sudden devaluation of shared assets in overlapping portfolios. We predict that although diversification may be good for individual institutions, it can create dangerous systemic effects, and as a result

  2. Generalizing Galileo's Passe-Dix Game

    Science.gov (United States)

    Hombas, Vassilios

    2012-01-01

    This article shows a generalization of Galileo's "passe-dix" game. The game was born following one of Galileo's [G. Galileo, "Sopra le Scoperte dei Dadi" (Galileo, Opere, Firenze, Barbera, Vol. 8). Translated by E.H. Thorne, 1898, pp. 591-594] explanations on a paradox that occurred in the experiment of tossing three fair "six-sided" dice.…

  3. Message passing with parallel queue traversal

    Science.gov (United States)

    Underwood, Keith D [Albuquerque, NM; Brightwell, Ronald B [Albuquerque, NM; Hemmert, K Scott [Albuquerque, NM

    2012-05-01

    In message passing implementations, associative matching structures are used to permit list entries to be searched in parallel fashion, thereby avoiding the delay of linear list traversal. List management capabilities are provided to support list entry turnover semantics and priority ordering semantics.

  4. TREsPASS Book 3: Creative Engagements

    NARCIS (Netherlands)

    Coles-Kemp, Lizzie; Hall, Peter

    2016-01-01

    In this book we examine the role that creative security engagements have played in the TREsPASS project. These engagements are part of a wider creative securities approach that explores the contributions that social practices make to protection of data and information. Our most popular creative

  5. Passing the Bond Issue (with Related Video)

    Science.gov (United States)

    Erickson, Paul W.

    2011-01-01

    When a bond referendum comes around for a school district, it often is the culmination of years of planning, strategizing and communicating to the public. Especially in these economic times, passing a building referendum is challenging. Complete transparency among the superintendent, school board and community is essential to communicate the…

  6. The influence of underwater turbulence on optical phase measurements

    Science.gov (United States)

    Redding, Brandon; Davis, Allen; Kirkendall, Clay; Dandridge, Anthony

    2016-05-01

    Emerging underwater optical imaging and sensing applications rely on phase-sensitive detection to provide added functionality and improved sensitivity. However, underwater turbulence introduces spatio-temporal variations in the refractive index of water which can degrade the performance of these systems. Although the influence of turbulence on traditional, non-interferometric imaging has been investigated, its influence on the optical phase remains poorly understood. Nonetheless, a thorough understanding of the spatio-temporal dynamics of the optical phase of light passing through underwater turbulence are crucial to the design of phase-sensitive imaging and sensing systems. To address this concern, we combined underwater imaging with high speed holography to provide a calibrated characterization of the effects of turbulence on the optical phase. By measuring the modulation transfer function of an underwater imaging system, we were able to calibrate varying levels of optical turbulence intensity using the Simple Underwater Imaging Model (SUIM). We then used high speed holography to measure the temporal dynamics of the optical phase of light passing through varying levels of turbulence. Using this method, we measured the variance in the amplitude and phase of the beam, the temporal correlation of the optical phase, and recorded the turbulence induced phase noise as a function of frequency. By bench marking the effects of varying levels of turbulence on the optical phase, this work provides a basis to evaluate the real-world potential of emerging underwater interferometric sensing modalities.

  7. Modeling drivers' passing duration and distance in a virtual environment

    Directory of Open Access Journals (Sweden)

    Haneen Farah

    2013-07-01

    The main contribution of this paper is in the empirical models developed for passing duration and distance which highlights the factors that affect drivers' passing behavior and can be used to enhance the passing models in simulation programs.

  8. Phase III Randomized Study of Rituximab/Carmustine, Etoposide, Cytarabine, and Melphalan (BEAM) Compared With Iodine-131 Tositumomab/BEAM With Autologous Hematopoietic Cell Transplantation for Relapsed Diffuse Large B-Cell Lymphoma: Results From the BMT CTN 0401 Trial

    Science.gov (United States)

    Vose, Julie M.; Carter, Shelly; Burns, Linda J.; Ayala, Ernesto; Press, Oliver W.; Moskowitz, Craig H.; Stadtmauer, Edward A.; Mineshi, Shin; Ambinder, Richard; Fenske, Timothy; Horowitz, Mary; Fisher, Richard; Tomblyn, Marcie

    2013-01-01

    Purpose This clinical trial evaluated standard-dose radioimmunotherapy with a chemotherapy-based transplantation regimen followed by autologous hematopoietic cell transplantation versus rituximab with the same regimen in patients with relapsed diffuse large B-cell lymphoma (DLBCL). Patients and Methods Patients with chemotherapy-sensitive persistent or relapsed DLBCL were randomly assigned to receive iodine-131 tositumomab (dosimetric dose of 5 mCi on day −19 and therapeutic dose of 0.75 Gy on day −12), carmustine 300 mg/m2 (day −6), etoposide 100 mg/m2 twice daily (days −5 to −2), cytarabine 100 mg/m2 twice daily (days −5 to −2), and melphalan 140 mg/m2 (day −1; B-BEAM) or rituximab 375 mg/m2 on days −19 and −12 and the same chemotherapy regimen (R-BEAM). Results Two hundred twenty-four patients were enrolled, with 113 patients randomly assigned to R-BEAM and 111 patients assigned to B-BEAM. Two-year progression-free survival (PFS) rates, the primary end point, were 48.6% (95% CI, 38.6% to 57.8%) for R-BEAM and 47.9% (95% CI, 38.2% to 57%; P = .94) for B-BEAM, and the 2-year overall survival (OS) rates were 65.6% (95% CI, 55.3% to 74.1%) for R-BEAM and 61% (95% CI, 50.9% to 69.9%; P = .38) for B-BEAM. The 100-day treatment-related mortality rates were 4.1% (95% CI, 0.2% to 8.0%) for R-BEAM and 4.9% (95% CI, 0.8% to 9.0%; P = .97) for B-BEAM. The maximum mucositis score was higher in the B-BEAM arm (0.72) compared with the R-BEAM arm (0.31; P < .001). Conclusion The B-BEAM and R-BEAM regimens produced similar 2-year PFS and OS rates for patients with chemotherapy-sensitive relapsed DLBCL. No differences in toxicities other than mucositis were noted. PMID:23478060

  9. Extensions of MAD Version 8 to Include Beam Acceleration

    International Nuclear Information System (INIS)

    Raubenheimer, Tor O

    2000-01-01

    In this paper, the authors describe modifications to MAD version 8.23 to include linear accelerator cavities and beam acceleration. An additional energy variable has been added which is modified as the beam passes through LCAV elements (linear accelerator cavities) and can be used as a constraint in matching commands. The calculation of the beta functions and phase advance is consistent with that in other codes that treat acceleration such as TRANSPORT or DIMAD. These modifications allow this version of MAD to be used for the design and modeling of linacs and the authors present examples from the Next Linear Collider design as well as a muon acceleration complex. The code is available from CERN or SLAC

  10. Techniques to sort Bessel beams

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2013-09-01

    Full Text Available -polar coordinate transformation, translating helically phased beams into a transverse phase gradient. By introducing two cylindrical lenses we can focus each of the azimuthal modes associated with each Bessel beam to a different lateral position in the Fourier...

  11. Facilitated beam-walking recovery during acute phase by kynurenic acid treatment in a rat model of photochemically induced thrombosis causing focal cerebral ischemia.

    Science.gov (United States)

    Abo, Masahiro; Yamauchi, Hideki; Suzuki, Masahiko; Sakuma, Mio; Urashima, Mitsuyoshi

    We previously demonstrated the presence of activated areas in the non-injured contralateral sensorimotor cortex in addition to the ipsilateral sensorimotor cortex of the area surrounding a brain infarction, using a rat model of focal photochemically induced thrombosis (PIT) and functional magnetic resonance imaging. Using this model, we next applied gene expression profiling to screen key molecules upregulated in the activated area. RNA was extracted from the ipsilateral and contralateral sensorimotor cortex to the focal brain infarction and from the sham controlled cortex, and hybridized to gene-expression profiling arrays containing 1,322 neurology-related genes. Results showed that glycine receptors were upregulated in both the ipsilateral and contralateral cortex to the focal ischemic lesion. To prove the preclinical significance of upregulated glycine receptors, kynurenic acid, an endogenous antagonist to glycine receptors on neuronal cells, was administered intrathecally. As a result, the kynurenic acid significantly improved behavioral recovery within 10 days from paralysis induced by the focal PIT (p beam walking. These results suggest that intrathecal administration of a glycine receptor antagonist may facilitate behavioral recovery during the acute phase after brain infarction. Copyright (c) 2006 S. Karger AG, Basel.

  12. A High-Granularity Timing Detector for the Phase-II upgrade of the ATLAS calorimeter system: detector concept description and first beam test results

    Science.gov (United States)

    Lacour, D.

    2018-02-01

    The expected increase of the particle flux at the high luminosity phase of the LHC (HL-LHC) with instantaneous luminosities up to 7.5ṡ1034 cm-2s-1 will have a severe impact on the ATLAS detector performance. The pile-up is expected to increase on average to 200 interactions per bunch crossing. The reconstruction performance for electrons, photons as well as jets and transverse missing energy will be severely degraded in the end-cap and forward region. A High Granularity Timing Detector (HGTD) is proposed in front of the liquid Argon end-cap and forward calorimeters for pile-up mitigation. This device should cover the pseudo-rapidity range of 2.4 to about 4.0. Low Gain Avalanche Detectors (LGAD) technology has been chosen as it provides an internal gain good enough to reach large signal over noise ratio needed for excellent time resolution. The requirements and overall specifications of the High Granular Timing Detector at the HL-LHC will be presented as well as the conceptual design of its mechanics and electronics. Beam test results and measurements of irradiated LGAD silicon sensors, such as gain and timing resolution, will be shown.

  13. Self-phase modulation in a thin fused silica plate upon interaction with a converging beam of down-chirped femtosecond radiation

    Energy Technology Data Exchange (ETDEWEB)

    Grudtsyn, Ya V; Zubarev, I G; Mamaev, S B; Mikheev, L D; Stepanov, S G; Yalovoi, V I [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Koribut, A V [Moscow Institute of Physics and Technology (State University), Dolgoprudny, Moscow region (Russian Federation); Kuchik, I E; Trofimov, V A [M. V. Lomonosov Moscow State University, Moscow (Russian Federation); Semjonov, S L [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-05-31

    The mechanism of spectral broadening and self-compression of down-chirped femtosecond pulses in the visible range (473 nm) upon nonlinear interaction of a converging Gaussian beam with a 1-mm-thick fused silica plate is experimentally and theoretically investigated. It is found experimentally that when the intensity increases and plasma is formed in the sample, the regime of femtosecond pulse splitting is transformed into the single-pulse generation regime during nonlinear interaction. As a result of selfcompression, the duration of the initial transform-limited pulse is reduced by a factor of 3. Based on the numerical solution of the generalised nonlinear Schrödinger equation, with the plasma formation disregarded, it is shown that the profile, spectrum and temporal phase of the pulse transmitted through the sample acquire a stationary shape behind the focal plane of the focusing mirror. The calculation results are in good agreement with experimental data. The possibility of parametric amplification of the pulse spectral components under given experimental conditions is discussed. (extreme light fields and their applications)

  14. Issues in Acceleration of A Muon Beam for a Neutrino Factory

    International Nuclear Information System (INIS)

    J. Delayen; D. Douglas; L. Harwood; V. Lebedev; C. Leemann; L. Merminga

    2001-01-01

    We have developed a concept for acceleration of a large phase-space, pulsed muon beam from 190 MeV to 50 GeV as part of a collaborative study of the feasibility of a neutrino factory based on in-flight decay of muons. The muon beam's initial energy spread was ∼20% and each bunch has the physical size of a soccer ball. Production of the muons will be quite expensive, so prevention of loss due to scraping or decay is critical. The former drives the system to large apertures and the latter calls for high real-estate-average gradients. The solution to be presented utilizes a 3 GeV linac to capture the beam, a 4-pass recirculating linac to get the beam to 10 GeV, and then a 5-pass linac to get the beam to 50 GeV. Throughout the system, longitudinal dynamics issues far outweighed transverse dynamics issues. This paper focuses on the issues surrounding the choice of superconducting rf structures over copper structures

  15. Milestone experiments for single pass UV/X-ray FELs

    Science.gov (United States)

    Ben-Zvi, Ilan

    1995-04-01

    In the past decade, significant advances have been made in the theory and technology of high brightness electron beams and single pass FELs. These developments facilitate the construction of practical UV and X-ray FELs and has prompted proposals to the DOE for the construction of such facilities. There are several important experiments to be performed before committing to the construction of dedicated user facilities. Two experiments are under construction in the IR, the UCLA self-amplified spontaneous emission experiment and the BNL laser seeded harmonic generation experiment. A multi-institution collaboration is being organized about a 210 MeV electron linac available at BNL and the 10 m long NISUS wiggler. This experiment will be done in the UV and will test various experimental aspects of electron beam dynamics, FEL exponential regime with gain guiding, start-up from noise, seeding and harmonic generation. These experiments will advance the state of FEL research and lead towards future dedicated users' facilities.

  16. The Continuous Electron Beam Accelerator Facility

    International Nuclear Information System (INIS)

    Grunder, H.A.; Bisognano, J.J.; Diamond, W.I.; Hartline, B.K.; Leemann, C.W.; Mougey, J.; Sundelin, R.M.; York, R.C.

    1987-01-01

    On February 13, 1987, construction started on the Continuous Electron Beam Accelerator Facility - a 4-GeV, 200-μA, continuous beam, electron accelerator facility designed for nuclear physics research. The machine has a racetrack configuration with two antiparallel, 500-MeV, superconducting linac segments connected by beam lines to allow four passes of recirculation. The accelerating structure consists of 1500-MHz, five-cell niobium cavities developed at Cornell University. A liquid helium cryogenic system cools the cavities to an operating temperature of 2 K. Beam extraction after any three of the four passes allows simultaneous delivery of up to three beams of independently variable currents and different, but correlated, energies to the three experimental areas. Beam breakup thresholds exceed the design current by nearly two orders of magnitude. Project completion and the start of physics operations are scheduled for 1993. The total estimated cost is $255 million

  17. A Phase 1/2 and Biomarker Study of Preoperative Short Course Chemoradiation With Proton Beam Therapy and Capecitabine Followed By Early Surgery for Resectable Pancreatic Ductal Adenocarcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Theodore S., E-mail: tshong1@partners.org [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States); Ryan, David P.; Borger, Darrell R.; Blaszkowsky, Lawrence S.; Yeap, Beow Y. [Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States); Ancukiewicz, Marek [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States); Deshpande, Vikram; Shinagare, Shweta [Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States); Wo, Jennifer Y.; Boucher, Yves [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States); Wadlow, Raymond C.; Kwak, Eunice L.; Allen, Jill N.; Clark, Jeffrey W.; Zhu, Andrew X. [Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States); Ferrone, Cristina R. [Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States); Mamon, Harvey J. [Department of Radiation Oncology, Brigham and Women' s Hospital/Dana-Farber Cancer Institute, Boston, Massachusetts (United States); Adams, Judith; Winrich, Barbara; Grillo, Tarin [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States); and others

    2014-07-15

    Purpose: To evaluate the safety, efficacy and biomarkers of short-course proton beam radiation and capecitabine, followed by pancreaticoduodenectomy in a phase 1/2 study in pancreatic ductal adenocarcinoma (PDAC) patients. Methods and Materials: Patients with radiographically resectable, biopsy-proven PDAC were treated with neoadjuvant short-course (2-week) proton-based radiation with capecitabine, followed by surgery and adjuvant gemcitabine. The primary objective was to demonstrate a rate of toxicity grade ≥3 of <20%. Exploratory biomarker studies were performed using surgical specimen tissues and peripheral blood. Results: The phase 2 dose was established at 5 daily doses of 5 GyE. Fifty patients were enrolled, of whom 35 patients were treated in the phase 2 portion. There were no grade 4 or 5 toxicities, and only 2 of 35 patients (4.1%) experienced a grade 3 toxicity event (chest wall pain grade 1, colitis grade 1). Of 48 patients eligible for analysis, 37 underwent pancreaticoduodenectomy. Thirty of 37 (81%) had positive nodes. Locoregional failure occurred in 6 of 37 resected patients (16.2%), and distant recurrence occurred in 35 of 48 patients (72.9%). With median follow-up of 38 months, the median progression-free survival for the entire group was 10 months, and overall survival was 17 months. Biomarker studies showed significant associations between worse survival outcomes and the KRAS point mutation change from glycine to aspartic acid at position 12, stromal CXCR7 expression, and circulating biomarkers CEA, CA19-9, and HGF (all, P<.05). Conclusions: This study met the primary endpoint by showing a rate of 4.1% grade 3 toxicity for neoadjuvant short-course proton-based chemoradiation. Treatment was associated with favorable local control. In exploratory analyses, KRAS{sup G12D} status and high CXCR7 expression and circulating CEA, CA19-9, and HGF levels were associated with poor survival.

  18. Electron Beam Diagnostics in Plasmas Based on Electron Beam Ionization

    Science.gov (United States)

    Leonhardt, Darrin; Leal-Quiros, Edbertho; Blackwell, David; Walton, Scott; Murphy, Donald; Fernsler, Richard; Meger, Robert

    2001-10-01

    Over the last few years, electron beam ionization has been shown to be a viable generator of high density plasmas with numerous applications in materials modification. To better understand these plasmas, we have fielded electron beam diagnostics to more clearly understand the propagation of the beam as it travels through the background gas and creates the plasma. These diagnostics vary greatly in sophistication, ranging from differentially pumped systems with energy selective elements to metal 'hockey pucks' covered with thin layers of insulation to electrically isolate the detector from the plasma but pass high energy beam electrons. Most importantly, absolute measurements of spatially resolved beam current densities are measured in a variety of pulsed and continuous beam sources. The energy distribution of the beam current(s) will be further discussed, through experiments incorporating various energy resolving elements such as simple grids and more sophisticated cylindrical lens geometries. The results are compared with other experiments of high energy electron beams through gases and appropriate disparities and caveats will be discussed. Finally, plasma parameters are correlated to the measured beam parameters for a more global picture of electron beam produced plasmas.

  19. Temperature feedback control for long-term carrier-envelope phase locking

    Science.gov (United States)

    Chang, Zenghu [Manhattan, KS; Yun, Chenxia [Manhattan, KS; Chen, Shouyuan [Manhattan, KS; Wang, He [Manhattan, KS; Chini, Michael [Manhattan, KS

    2012-07-24

    A feedback control module for stabilizing a carrier-envelope phase of an output of a laser oscillator system comprises a first photodetector, a second photodetector, a phase stabilizer, an optical modulator, and a thermal control element. The first photodetector may generate a first feedback signal corresponding to a first portion of a laser beam from an oscillator. The second photodetector may generate a second feedback signal corresponding to a second portion of the laser beam filtered by a low-pass filter. The phase stabilizer may divide the frequency of the first feedback signal by a factor and generate an error signal corresponding to the difference between the frequency-divided first feedback signal and the second feedback signal. The optical modulator may modulate the laser beam within the oscillator corresponding to the error signal. The thermal control unit may change the temperature of the oscillator corresponding to a signal operable to control the optical modulator.

  20. Study of the α and β phases of quartz by neutron multiple diffraction

    International Nuclear Information System (INIS)

    Mazzocchi, V.L.

    1984-01-01

    Crystal structures of α and β phases of quartz are studied, employing neutron multiple diffraction as a method of analysis. Theoretical multiple diffraction patterns in a many-beam case were determined by a computer program which calculates intensities of beams as sums of Taylor's series expansions, retaining terms up to a order n. Experimental 'umweg' and transmitted beam patterns were obtained for the 00.1 primary reflection of α and β phases of quartz. To calculate α - quartz multiple diffraction intensities it was necessary to determine the Dauphine twinning fraction for the crystal after having passed by the β-phase. For the two models of β-quartz a better agreement between experimental and calculated integrated intensities was found for the disordered structure model based on split-half-oxigen positions. (Author) [pt