WorldWideScience

Sample records for group velocity x-band

  1. Wake Component Detection in X-Band SAR Images for Ship Heading and Velocity Estimation

    Directory of Open Access Journals (Sweden)

    Maria Daniela Graziano

    2016-06-01

    Full Text Available A new algorithm for ship wake detection is developed with the aim of ship heading and velocity estimation. It exploits the Radon transform and utilizes merit indexes in the intensity domain to validate the detected linear features as real components of the ship wake. Finally, ship velocity is estimated by state-of-the-art techniques of azimuth shift and Kelvin arm wavelength. The algorithm is applied to 13 X-band SAR images from the TerraSAR-X and COSMO/SkyMed missions with different polarization and incidence angles. Results show that the vast majority of wake features are correctly detected and validated also in critical situations, i.e., when multiple wake appearances or dark areas not related to wake features are imaged. The ship route estimations are validated with truth-at-sea in seven cases. Finally, it is also verified that the algorithm does not detect wakes in the surroundings of 10 ships without wake appearances.

  2. Distinguishing zero-group-velocity modes in photonic crystals

    International Nuclear Information System (INIS)

    Ghebrebrhan, M.; Ibanescu, M.; Johnson, Steven G.; Soljacic, M.; Joannopoulos, J. D.

    2007-01-01

    We examine differences between various zero-group-velocity modes in photonic crystals, including those that arise from Bragg diffraction, anticrossings, and band repulsion. Zero-group velocity occurs at points where the group velocity changes sign, and therefore is conceptually related to 'left-handed' media, in which the group velocity is opposite to the phase velocity. We consider this relationship more quantitatively in terms of the Fourier decomposition of the modes, by defining a measure of how much the ''average'' phase velocity is parallel to the group velocity--an anomalous region is one in which they are mostly antiparallel. We find that this quantity can be used to qualitatively distinguish different zero-group-velocity points. In one dimension, such anomalous regions are found never to occur. In higher dimensions, they are exhibited around certain zero-group-velocity points, and lead to unusual enhanced confinement behavior in microcavities

  3. Determining the group velocity dispersion by field analysis for the LP0X, LP1X, and LP2X mode groups independently of the fiber length: applications to step-index fibers

    DEFF Research Database (Denmark)

    Israelsen, Stine Møller; Usuga Castaneda, Mario A.; Rottwitt, Karsten

    2017-01-01

    By knowing the electric field distribution of a guided mode in an optical fiber, we are able to evaluate the group velocity dispersion in a weakly guiding step-index fiber for a pure mode in the LP0X, LP1X, and LP2X mode groups independently of the fiber length. We demonstrate the method numerica...

  4. Propagation of the Semidiurnal Internal Tide: Phase Velocity Versus Group Velocity

    Science.gov (United States)

    Zhao, Zhongxiang

    2017-12-01

    The superposition of two waves of slightly different wavelengths has long been used to illustrate the distinction between phase velocity and group velocity. The first-mode M2 and S2 internal tides exemplify such a two-wave model in the natural ocean. The M2 and S2 tidal frequencies are 1.932 and 2 cycles per day, respectively, and their superposition forms a spring-neap cycle in the semidiurnal band. The spring-neap cycle acts like a wave, with its frequency, wave number, and phase being the differences of the M2 and S2 internal tides. The spring-neap cycle and energy of the semidiurnal internal tide propagate at the group velocity. Long-range propagation of M2 and S2 internal tides in the North Pacific is observed by satellite altimetry. Along a 3,400 km beam spanning 24°-54°N, the M2 and S2 travel times are 10.9 and 11.2 days, respectively. For comparison, it takes the spring-neap cycle 21.1 days to travel over this distance. Spatial maps of the M2 phase velocity, the S2 phase velocity, and the group velocity are determined from phase gradients of the corresponding satellite observed internal tide fields. The observed phase and group velocities agree with theoretical values estimated using the World Ocean Atlas 2013 annual-mean ocean stratification.

  5. Low-bias flat band-stop filter based on velocity modulated gaussian graphene superlattice

    Science.gov (United States)

    Sattari-Esfahlan, S. M.; Shojaei, S.

    2018-05-01

    Transport properties of biased planar Gaussian graphene superlattice (PGGSL) with Fermi velocity barrier is investigated by transfer matrix method (TMM). It is observed that enlargement of bias voltage over miniband width breaks the miniband to WSLs leads to suppressing resonant tunneling. Transmission spectrum shows flat wide stop-band property controllable by external bias voltage with stop-band width of near 200 meV. The simulations demonstrate that strong velocity barriers prevent tunneling of Dirac electrons leading to controllable enhancement of stop-band width. By increasing ratio of Fermi velocity in barriers to wells υc stop-band width increase. As wide transmission stop-band width (BWT) of filter is tunable from 40 meV to 340 meV is obtained by enhancing ratio of υc from 0.2 to 1.5, respectively. Proposed structure suggests easy tunable wide band-stop electronic filter with a modulated flat stop-band characteristic by height of electrostatic barrier and structural parameters. Robust sensitivity of band width to velocity barrier intensity in certain bias voltages and flat band feature of proposed filter may be opens novel venue in GSL based flat band low noise filters and velocity modulation devices.

  6. Coded excitation and sub-band processing for blood velocity estmation in medical ultrasound

    DEFF Research Database (Denmark)

    Gran, Fredrik; Udesen, Jesper; Jensen, Jørgen Arendt

    2007-01-01

    This paper investigates the use of broadband coded excitation and subband processing for blood velocity estimation in medical ultrasound. In conventional blood velocity estimation a long (narrow-band) pulse is emitted and the blood velocity is estimated using an auto-correlation based approach....... However, the axial resolution of the narrow-band pulse is too poor for brightness-mode (B-mode) imaging. Therefore, a separate transmission sequence is used for updating the B-mode image, which lowers the overall frame-rate of the system. By using broad-band excitation signals, the backscattered received...... signal can be divided into a number of narrow frequency bands. The blood velocity can be estimated in each of the bands and the velocity estimates can be averaged to form an improved estimate. Furthermore, since the excitation signal is broadband, no secondary B-mode sequence is required, and the frame...

  7. Attenuation and velocity dispersion in the exploration seismic frequency band

    Science.gov (United States)

    Sun, Langqiu

    In an anelastic medium, seismic waves are distorted by attenuation and velocity dispersion, which depend on petrophysical properties of reservoir rocks. The effective attenuation and velocity dispersion is a combination of intrinsic attenuation and apparent attenuation due to scattering, transmission response, and data acquisition system. Velocity dispersion is usually neglected in seismic data processing partly because of insufficient observations in the exploration seismic frequency band. This thesis investigates the methods of measuring velocity dispersion in the exploration seismic frequency band and interprets the velocity dispersion data in terms of petrophysical properties. Broadband, uncorrelated vibrator data are suitable for measuring velocity dispersion in the exploration seismic frequency band, and a broad bandwidth optimizes the observability of velocity dispersion. Four methods of measuring velocity dispersion in uncorrelated vibrator VSP data are investigated, which are the sliding window crosscorrelation (SWCC) method, the instantaneous phase method, the spectral decomposition method, and the cross spectrum method. Among them, the SWCC method is a new method and has satisfactory robustness, accuracy, and efficiency. Using the SWCC method, velocity dispersion is measured in the uncorrelated vibrator VSP data from three areas with different geological settings, i.e., Mallik gas hydrate zone, McArthur River uranium mines, and Outokumpu crystalline rocks. The observed velocity dispersion is fitted to a straight line with respect to log frequency for a constant (frequency-independent) Q value. This provides an alternative method for calculating Q. A constant Q value does not directly link to petrophysical properties. A modeling study is implemented for the Mallik and McArthur River data to interpret the velocity dispersion observations in terms of petrophysical properties. The detailed multi-parameter petrophysical reservoir models are built according to

  8. Block 3 X-band receiver-exciter

    Science.gov (United States)

    Johns, C. E.

    1987-01-01

    The development of an X-band exciter, for use in the X-Band Uplink Subsystem, was completed. The exciter generates the drive signal for the X-band transmitter and also generates coherent test signals for the S- and X-band Block 3 translator and a Doppler reference signal for the Doppler extractor system. In addition to the above, the exciter generates other reference signals that are described. Also presented is an overview of the exciter design and some test data taken on the prototype. A brief discussion of the Block 3 Doppler extractor is presented.

  9. X-Band CubeSat Communication System Demonstration

    Science.gov (United States)

    Altunc, Serhat; Kegege, Obadiah; Bundick, Steve; Shaw, Harry; Schaire, Scott; Bussey, George; Crum, Gary; Burke, Jacob C.; Palo, Scott; O'Conor, Darren

    2015-01-01

    Today's CubeSats mostly operate their communications at UHF- and S-band frequencies. UHF band is presently crowded, thus downlink communications are at lower data rates due to bandwidth limitations and are unreliable due to interference. This research presents an end-to-end robust, innovative, compact, efficient and low cost S-band uplink and X-band downlink CubeSat communication system demonstration between a balloon and a Near Earth Network (NEN) ground system. Since communication systems serve as umbilical cords for space missions, demonstration of this X-band communication system is critical for successfully supporting current and future CubeSat communication needs. This research has three main objectives. The first objective is to design, simulate, and test a CubeSat S- and X-band communication system. Satellite Tool Kit (STK) dynamic link budget calculations and HFSS Simulations and modeling results have been used to trade the merit of various designs for small satellite applications. S- and X-band antennas have been tested in the compact antenna test range at Goddard Space Flight Center (GSFC) to gather radiation pattern data. The second objective is simulate and test a CubeSat compatible X-band communication system at 12.5Mbps including S-band antennas, X-band antennas, Laboratory for Atmospheric and Space Physics (LASP) /GSFC transmitter and an S-band receiver from TRL-5 to TRL-8 by the end of this effort. Different X-band communication system components (antennas, diplexers, etc.) from GSFC, other NASA centers, universities, and private companies have been investigated and traded, and a complete component list for the communication system baseline has been developed by performing analytical and numerical analysis. This objective also includes running simulations and performing trades between different X-band antenna systems to optimize communication system performance. The final objective is to perform an end-to-end X-band CubeSat communication system

  10. Exciter For X-Band Transmitter And Receiver

    Science.gov (United States)

    Johns, Carl E.

    1989-01-01

    Report describes developmental X-band exciter for X-band uplink subsystem of Deep Space Network. X-band transmitter-exciting signal expected to have fractional frequency stability of 5.2 X 10 to negative 15th power during 1,000-second integration period. Generates coherent test signals for S- and X-band Block III translator of Deep Space Network, Doppler-reference signal for associated Doppler-extractor system, first-local-oscillator signal for associated receiver, and reference signal for associated ranging subsystem. Tests of prototype exciter show controlling and monitoring and internal phase-correcting loops perform according to applicable design criteria. Measurements of stability of frequency and of single-sideband noise spectral density of transmitter-exciting signal made subsequently.

  11. Broad-band hard X-ray reflectors

    DEFF Research Database (Denmark)

    Joensen, K.D.; Gorenstein, P.; Hoghoj, P.

    1997-01-01

    Interest in optics for hard X-ray broad-band application is growing. In this paper, we compare the hard X-ray (20-100 keV) reflectivity obtained with an energy-dispersive reflectometer, of a standard commercial gold thin-film with that of a 600 bilayer W/Si X-ray supermirror. The reflectivity...... of the multilayer is found to agree extraordinarily well with theory (assuming an interface roughness of 4.5 Angstrom), while the agreement for the gold film is less, The overall performance of the supermirror is superior to that of gold, extending the band of reflection at least a factor of 2.8 beyond...... that of the gold, Various other design options are discussed, and we conclude that continued interest in the X-ray supermirror for broad-band hard X-ray applications is warranted....

  12. Advances in X-Band and S-Band Linear Accelerators for Security, NDT, and Other Applications

    CERN Document Server

    Mishin, Andrey V

    2005-01-01

    At AS&E High Energy Systems Division, we designed several new advanced high energy electron beam and X-ray sources. Our primary focus has always been in building the world's most portable commercial X-band accelerators. Today, our X-band systems frequently exceed performance of the similar S-band machines, while they are more portable compared to the latter. The new designs of the X-band accelerators in the most practical energy range from 1 MeV to 6 MeV have been tested delivering outstanding results. Seventy 6 MeV X-band linacs systems have been produced. The most compact linac for security is used by AS&E in a self-shielded, Shaped Energy™ cargo screening system. We pioneered using the X-band linear accelerators for CT, producing high quality images of oil pipes and wood logs. An X-band linear accelerator head on a robotic arm has been used for electron beam radiation curing of an odd-shaped graphite composite part. We developed the broad-range 4 MeV to over 10 MeV energy-regulated X-band ...

  13. Valence band structure of InAs(1-x)Bi(x) and InSb(1-x)Bi(x) alloy semiconductors calculated using valence band anticrossing model.

    Science.gov (United States)

    Samajdar, D P; Dhar, S

    2014-01-01

    The valence band anticrossing model has been used to calculate the heavy/light hole and spin-orbit split-off energies in InAs(1-x)Bi(x) and InSb(1-x)Bi(x) alloy systems. It is found that both the heavy/light hole, and spin-orbit split E + levels move upwards in energy with an increase in Bi content in the alloy, whereas the split E - energy for the holes shows a reverse trend. The model is also used to calculate the reduction of band gap energy with an increase in Bi mole fraction. The calculated values of band gap variation agree well with the available experimental data.

  14. Breakdown Characteristics Study on an 18 Cell X-band Structure

    International Nuclear Information System (INIS)

    Wang, F

    2008-01-01

    A CLIC designed 18 cells, low group velocity (2.4% to 1.0% c), X-band (11.4 GHz) accelerator structure (denoted T18) was designed at CERN, its cells were built at KEK, and it was assembled and tested at SLAC. An interesting feature of this structure is that the gradient in the last cell is about 50% higher than that in the first cell. This structure has been RF conditioned at SLAC NLCTA for about 1400 hours where it incurred about 2200 breakdowns. This paper presents the characteristics of these breakdowns, including (1) the breakdown rate dependence on gradient, pulse width and conditioning time, (2) the breakdown distribution along the structure, (3) relation between breakdown and pulsed heating dependence study and (4) electric field decay time for breakdown changing over the whole conditioning time. Overall, this structure performed very well, having a final breakdown rate of less than 1e-6/pulse/m at 106 MV/m with 230 ns pulse width

  15. Breakdown Characteristics Study on an 18 Cell X-band Structure

    International Nuclear Information System (INIS)

    Wang Faya

    2009-01-01

    A CLIC designed 18 cells, low group velocity (2.4% to 1.0% c), X-band (11.4 GHz) accelerator structure (denoted T18) was designed at CERN, its cells were built at KEK, and it was assembled and tested at SLAC. An interesting feature of this structure is that the gradient in the last cell is about 50% higher than that in the first cell. This structure has been RF conditioned at SLAC NLCTA for about 1400 hours where it incurred about 2200 breakdowns. This paper presents the characteristics of these breakdowns, including 1) the breakdown rate dependence on gradient, pulse width and conditioning time, 2) the breakdown distribution along the structure, 3) relation between breakdown and pulsed heating dependence study and 4) electric field decay time for breakdown changing over the whole conditioning time. Overall, this structure performed very well, having a final breakdown rate of less than 1e-6/pulse/m at 106 MV/m with 230 ns pulse width.

  16. On whistler-mode group velocity

    International Nuclear Information System (INIS)

    Sazhin, S.S.

    1986-01-01

    An analytical of the group velocity of whistler-mode waves propagating parallel to the magnetic field in a hot anisotropic plasma is presented. Some simple approximate formulae, which can be used for the magnetospheric applications, are derived. These formulae can predict some properties of this group velocity which were not previously recognized or were obtained by numerical methods. In particular, it is pointed out that the anisotropy tends to compensate for the influence of the electron temperature on the value of the group velocity when the wave frequency is well below the electron gyrofrequency. It is predicted, that under conditions at frequencies near the electron gyrofrequency, this velocity tends towards zero

  17. A programmable ultra-low noise X-band exciter.

    Science.gov (United States)

    MacMullen, A; Hoover, L R; Justice, R D; Callahan, B S

    2001-07-01

    A programmable ultra-low noise X-band exciter has been developed using commercial off-the-shelf components. Its phase noise is more than 10 dB below the best available microwave synthesizers. It covers a 7% frequency band with 0.1-Hz resolution. The X-band output at +23 dBm is a combination of signals from an X-band sapphire-loaded cavity oscillator (SLCO), a low noise UHF frequency synthesizer, and special-purpose frequency translation and up-conversion circuitry.

  18. BANYAN. III. Radial velocity, rotation, and X-ray emission of low-mass star candidates in nearby young kinematic groups

    Energy Technology Data Exchange (ETDEWEB)

    Malo, Lison; Artigau, Étienne; Doyon, René; Lafrenière, David; Albert, Loïc; Gagné, Jonathan, E-mail: malo@astro.umontreal.ca, E-mail: doyon@astro.umontreal.ca [Département de physique and Observatoire du Mont-Mégantic, Université de Montréal, Montréal, QC H3C 3J7 (Canada)

    2014-06-10

    Based on high-resolution spectra obtained with PHOENIX at Gemini-South, CRIRES at VLT-UT1, and ESPaDOnS at the Canada-France-Hawaii Telescope, we present new measurements of the radial and projected rotational velocities of 219 low-mass stars. The target likely membership was initially established using the Bayesian analysis tool recently presented in Malo et al., taking into account only the position, proper motion, and photometry of the stars to assess their membership probability. In the present study, we include radial velocity as an additional input to our analysis, and in doing so we confirm the high membership probability for 130 candidates: 27 in β Pictoris, 22 in Tucana-Horologium, 25 in Columba, 7 in Carina, 18 in Argus and 18 in AB Doradus, and 13 with an ambiguous membership. Our analysis also confirms the membership of 57 stars proposed in the literature. A subsample of 16 candidates was observed at 3 or more epochs, allowing us to discover 6 new spectroscopic binaries. The fraction of binaries in our sample is 25%, consistent with values in the literature. Of the stars in our sample, 20% show projected rotational velocities (vsin i) higher than 30 km s{sup –1} and therefore are considered as fast rotators. A parallax and other youth indicators are still needed to fully confirm the 130 highly probable candidates identified here as new bona fide members. Finally, based on the X-ray emission of bona fide and highly probable group members, we show that for low-mass stars in the 12-120 Myr age range, the X-ray luminosity is an excellent indicator of youth and better than the more traditionally used R {sub X} parameter, the ratio of X-ray to bolometric luminosity.

  19. Group velocity tomography and regionalization in Italy and bordering areas

    International Nuclear Information System (INIS)

    Pontevivo, A.; Panza, G.F.

    2001-10-01

    More than one hundred group velocity dispersion curves of the fundamental mode of Rayleigh waves have been processed to obtain tomographic maps, in the period range from 10 s to 35 s, for the Italian peninsula and bordering areas. We compute average dispersion relations over a 1 deg. x 1 deg. grid, and, since the lateral resolving power of our data set is about 200 km, we group the cells of the grid accordingly to their dispersion curves. In this way and without a priori geological constraints, we define seven different regions, each characterised by a distinctive mean group velocity dispersion curve. The resulting regionalization can be easily correlated with the main tectonic features of the study area and mimics a recently proposed structural sketch. Average models of the shear wave velocity in the crust and in the upper mantle for a few selected regions are presented. The very low S-wave velocity values found in the uppermost upper mantle of the Southern Tyrrhenian basin are consistent with a large percentage of partial melting, well in agreement with the presence of the Vavilov-Magnaghi and Marsili huge volcanic bodies. (author)

  20. X-Band RF Gun Development

    International Nuclear Information System (INIS)

    Vlieks, A.E.

    2012-01-01

    In support of the MEGa-ray program at LLNL and the High Gradient research program at SLAC, a new X-band multi-cell RF gun is being developed. This gun, similar to earlier guns developed at SLAC for Compton X-ray source program, will be a standing wave structure made of 5.5 cells operating in the pi mode with copper cathode. This gun was designed following criteria used to build SLAC X-band high gradient accelerating structures. It is anticipated that this gun will operate with surface electric fields on the cathode of 200 MeV/m with low breakdown rate. RF will be coupled into the structure through a final cell with symmetric duel feeds and with a shape optimized to minimize quadrupole field components. In addition, geometry changes to the original gun, operated with Compton X-ray source, will include a wider RF mode separation, reduced surface electric and magnetic fields.

  1. Rayleigh Wave Group Velocity Tomography from Microseisms in the Acambay Graben

    Science.gov (United States)

    Valderrama Membrillo, S.; Aguirre, J.; Zuñiga-Davila, R.; Iglesias, A.

    2017-12-01

    The Acambay graben is one of the most outstanding structures of the Trans-Mexican Volcanic Belt. The Acambay graben has a length of 80km and 15 to 18 km wide and reaches a maximum height of 400 m in its central part. We obtained the group velocity seismic tomography for the Acamaby graben for three different frequencies (f = 0.1, 0.2 and 0.3 Hz). The graben was divided into 6x6 km cells for the tomography and covered a total area of 1008 km2. Seismic noise data from 10 broadband seismic stations near the Acambay graben were used to extract the surface wave arrival-times between all station pairs. The Green's function was recovered in each stations pair by cross-correlation technique. This technique was applied to seismic recordings collected on the vertical component of 10 broadband stations for a continuous recording period of 5 months. Data processing consisted of removing instrumental response, mean, and trend. After that, we applied time domain normalization, a spectral whitening and applied band-pas filtering of 0.1 to 1 Hz. There are shallow studies of the Acambay graben. But little is known of the distribution of deep graben structures. This study estimated the surface wave velocity deep structure. The structures at the frequency 0.3 Hz indicate a lower depth than the remaining frequencies. The result for this frequency show consistencies with previous studies of gravimetry and resistivity, also defines the fault system of Temascalcingo.

  2. Analysis of Ground Displacements in Taipei Area by Using High Resolution X-band SAR Interferometry

    Science.gov (United States)

    Tung, H.; Chen, H. Y.; Hu, J. C.

    2014-12-01

    Located at the northern part of Taiwan, Taipei is the most densely populated city and the center of politic, economic, and culture of this island. North of the Taipei basin, the active Tatun volcano group with the eruptive potential to devastate the entire Taipei is only 15 km away from the capital Taipei. Furthermore, the active Shanchiao fault located in the western margin of Taipei basin. Therefore, it is not only an interesting scientific topic but also a strong social impact to better understand the assessment and mitigation of geological hazard in the metropolitan Taipei city. In this study, we use 12 high resolution X-band SAR images from the new generation COSMO-SkyMed (CSK) constellation for associating with leveling and GPS data to monitor surface deformation around the Shanchiao fault and the Tatun volcano group. The stripmap mode of CSK SAR images provides spatial resolution of 3 m x 3 m, which is one order of magnitude better than the previous available satellite SAR data. Furthermore, the more frequent revisit of the same Area of Interest (AOI) of the present X-band missions provides massive datasets to avoid the baseline limitation and temporal decorrelation to improve the temporal resolution of deformation in time series. After transferring the GPS vectors and leveling data to the LOS direction by referring to continuous GPS station BANC, the R square between PS velocities and GPS velocities is approximate to 0.9, which indicates the high reliability of our PSInSAR result. In addition, the well-fitting profiles between leveling data and PSInSAR result along two leveling routes both demonstrate that the significant deformation gradient mainly occurs along the Shanchiao fault. The severe land subsidence area is located in the western part of Taipei basin just next to the Shanchiao fault with a maximum of SRD rate of 30 mm/yr. However, the severe subsidence area, Wuku, is also one industrial area in Taipei which could be attributed to anthropogenic

  3. Engineering design and fabrication of X-Band components

    CERN Document Server

    Filippova, M; Solodko, A; Riddone, G; Syratchev, I

    2011-01-01

    The CLIC RF frequency has been changed in 2008 from the initial 30 GHz to the European X-band 11.994 GHz permitting beam independent power production using klystrons for the accelerating structure testing. X-band klystron test facilities at 11.424 GHz are operated at SLAC and at KEK [1], and they are used by the CLIC study in the framework of the X-band structure collaboration for testing accelerating structures scaled to that frequency [2]. CERN is currently building a klystron test-stand operating at 11.994 GHz. In addition X-FEL projects at PSI and Sincrotrone Trieste operate at 11.4 GHz. Therefore several RF components accommodating frequencies from 11.424 to 11.994 GHz are required. The engineering design of these RF components (high power and compact loads, bi-directional couplers, X-band splitters, hybrids, phase shifters, variable power attenuators) and the main fabrication processes are presented here.

  4. Band structure of Mgsub(x)Znsub(1-x)Te alloys

    International Nuclear Information System (INIS)

    Laugier, A.; Montegu, B.; Barbier, D.; Chevallier, J.; Guillaume, J.C.; Somogyi, K.

    1980-01-01

    The band structure of Mgsub(x)Znsub(1-x)Te alloys is studied using a double beam wavelength modulated system in first derivative mode. Modulated reflectivity measurements are made from 82 to 300 K within spectral range 2500 to 5400 A. Structures corresponding to the E 0 , E 0 + Δ 0 , E 1 , E 1 + Δ 1 , e 1 and e 1 + Δ 1 critical points are indexed on the basis of existing band calculations for ZnTe. (author)

  5. Portable, x-band, linear accelerator systems

    International Nuclear Information System (INIS)

    Schonberg, R.G.; Deruyter, H.; Fowkes, W.R.; Johnson, W.A.; Miller, R.H.; Potter, J.M.; Weaver, J.N.

    1985-01-01

    Three light-weight, x-band, electron accelerators have been developed to provide a series of highly portable sources of x-rays and neutrons for nondestructive testing. The 1.5 MeV x-ray unit has a 200 kW magnetron for an RF source and an air-cooled, traveling wave accelerating structure to minimize its weight. The 4 and 6 MeV units share the same drive system which contains a 1.2 MW magnetron. The 4 MeV unit uses a traveling-wave guide to produce x-rays and the 6MeV unit uses a standing-wave guide to produce x-rays or neutrons. The choice of 9.3 GHz was dictated by the availability of a high power coaxial magnetron and by the obvious dimensional and weight advantages of a higher frequency over the more common S-band frequencies around 3 GHz

  6. Portable, x-band, linear accelerator systems

    International Nuclear Information System (INIS)

    Schonberg, R.G.; Deruyter, H.; Fowkes, W.R.; Johnson, W.A.; Miller, R.H.; Potter, J.M.; Weaver, J.N.

    1985-01-01

    Three light-weight, x-band, electron accelerators have been developed to provide a series of highly portable sources of x-rays and neutrons for non-destructive testing. The 1.5 MeV x-ray unit has a 200 kW magnetron for an RF source and an air-cooled, traveling wave accelerating structure to minimize its weight. The 4 and 6 MeV units share the same drive system which contains a 1.2 MW magnetron. The 4 MeV unit uses a traveling-wave guide to produce x-rays and the 6MeV unit uses a standing-wave guide to produce x-rays or neutrons. The choice of 9.3 GHz was dictated by the availability of a high power coaxial magnetron and by the obvious dimensional and weight advantages of a higher frequency over the more common S-band frequencies around 3 GHz

  7. Comparison and fit of the two and six band k.p models for the band edge structure of Pbsub(1-x)Snsub(x)Te

    International Nuclear Information System (INIS)

    Weissman, Y.

    1975-10-01

    The band edge structure of Pbsub(1-x)Snsub(x)Te is derived in detail using a two band ellipsoidal model and compared with a more rigorous calculation based on six bands. A quantitative comparison is made for two values of the energy gap, corresponding to the cases where x=0 and x=0.17. It was found that, for the occupied states in nondegenerate materials, both models are practically equivalent. Discrepancies may occur only in high degeneracies or deep inversion layers. The agreement between both models was significantly improved by introducing an effective energy gap in the two band model. It is suggested that the use of the effective energy gap may improve the agreement between the two band model and experiment whenever the details of the band edge structure enter the interpretation of the experimental results. (author)

  8. X-band uplink feedcone capabilities, components, and layout

    Science.gov (United States)

    Marlin, H.; Freiley, A.; Hartop, R.

    1986-01-01

    Two new X-(7.2 GHz up, 8.4 GHz down) and S-band (2.1 to 2.3 Ghz) common aperture (XSC) feedcones are being added to the DSS 45 and DSS 65 34-Meter Efficiency Antennas. These new feedcones are modifications of the existing SXC feedcone design incorporating a new high power (20-kW) X-band transmitter. The modified Antenna Microwave Subsystem design also incorporates two additional X-band low noise amplifiers and greater phase stability performance to meet both the increased stability requirements for Galileo gravity wave experiments and requirements for spacecraft navigation near the Sun. A third XSC will be constructed for DSS 15 later.

  9. Design and analysis of X-band femtosecond linac

    Energy Technology Data Exchange (ETDEWEB)

    Uesaka, M; Kozawa, T; Takeshita, A; Kobayashi, T; Ueda, T; Miya, K [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

    1997-03-01

    Femtosecond quantum phenomena research project is proposed at Nuclear Engineering Research Laboratory, University of Tokyo. The research facility consists of an X-band (11.424GHz) femtosecond electron linac, a femtosecond wavelength tunable laser, two S-band (2.856GHz) picosecond electron linacs and measuring equipments. Especially, we aim to generate a 100 fs (FWHM) electron single bunch with more than 1 nC at the X-band femtosecond linac. Ultrafast processes in radiation physics, chemistry, material science and microscopic electromagnetic phenomena are going to be analyzed there. Here the design and analysis of an X-band femtosecond linac is presented. The simulation of electron dynamics is carried out including magnetic pulse compression by using PARMELA and SUPERFISH. It is found by the simulation that the 600 ps (tail-to-tail) electron emission from a 200 kV thermionic gun can be bunched and compressed to 110 fs (FWHM) with the charge of 0.8 nC which gives 7.3 kA. We plan to use one high power X-band klystron which can supply 60 MW with more than 200 ns pulse duration. The flatness of plateau of the pulse should be 0.2% for stable ultrashort bunch generation. (author)

  10. X-band RF gun and linac for medical Compton scattering X-ray source

    International Nuclear Information System (INIS)

    Dobashi, Katsuhito; Uesaka, Mitsuru; Fukasawa, Atsushi; Sakamoto, Fumito; Ebina, Futaro; Ogino, Haruyuki; Urakawa, Junji; Higo, Toshiyasu; Akemoto, Mitsuo; Hayano, Hitoshi; Nakagawa, Keiichi

    2004-01-01

    Compton scattering hard X-ray source for 10-80 keV are under construction using the X-band (11.424 GHz) electron linear accelerator and YAG laser at Nuclear Engineering Research laboratory, University of Tokyo. This work is a part of the national project on the development of advanced compact medical accelerators in Japan. National Institute for Radiological Science is the host institute and U.Tokyo and KEK are working for the X-ray source. Main advantage is to produce tunable monochromatic hard (10-80 keV) X-rays with the intensities of 108-1010 photons/s (at several stages) and the table-top size. Second important aspect is to reduce noise radiation at a beam dump by adopting the deceleration of electrons after the Compton scattering. This realizes one beamline of a 3rd generation SR source at small facilities without heavy shielding. The final goal is that the linac and laser are installed on the moving gantry. We have designed the X-band (11.424 GHz) traveling-wave-type linac for the purpose. Numerical consideration by CAIN code and luminosity calculation are performed to estimate the X-ray yield. X-band thermionic-cathode RF-gun and RDS(Round Detuned Structure)-type X-band accelerating structure are applied to generate 50 MeV electron beam with 20 pC microbunches (104) for 1 microsecond RF macro-pulse. The X-ray yield by the electron beam and Q-switch Nd:YAG laser of 2 J/10 ns is 107 photons/RF-pulse (108 photons/sec at 10 pps). We design to adopt a technique of laser circulation to increase the X-ray yield up to 109 photons/pulse (1010 photons/s). 50 MW X-band klystron and compact modulator have been constructed and now under tuning. The construction of the whole system has started. X-ray generation and medical application will be performed in the early next year

  11. X-band RF gun and linac for medical Compton scattering X-ray source

    Science.gov (United States)

    Dobashi, Katsuhito; Uesaka, Mitsuru; Fukasawa, Atsushi; Sakamoto, Fumito; Ebina, Futaro; Ogino, Haruyuki; Urakawa, Junji; Higo, Toshiyasu; Akemoto, Mitsuo; Hayano, Hitoshi; Nakagawa, Keiichi

    2004-12-01

    Compton scattering hard X-ray source for 10-80 keV are under construction using the X-band (11.424 GHz) electron linear accelerator and YAG laser at Nuclear Engineering Research laboratory, University of Tokyo. This work is a part of the national project on the development of advanced compact medical accelerators in Japan. National Institute for Radiological Science is the host institute and U.Tokyo and KEK are working for the X-ray source. Main advantage is to produce tunable monochromatic hard (10-80 keV) X-rays with the intensities of 108-1010 photons/s (at several stages) and the table-top size. Second important aspect is to reduce noise radiation at a beam dump by adopting the deceleration of electrons after the Compton scattering. This realizes one beamline of a 3rd generation SR source at small facilities without heavy shielding. The final goal is that the linac and laser are installed on the moving gantry. We have designed the X-band (11.424 GHz) traveling-wave-type linac for the purpose. Numerical consideration by CAIN code and luminosity calculation are performed to estimate the X-ray yield. X-band thermionic-cathode RF-gun and RDS(Round Detuned Structure)-type X-band accelerating structure are applied to generate 50 MeV electron beam with 20 pC microbunches (104) for 1 microsecond RF macro-pulse. The X-ray yield by the electron beam and Q-switch Nd:YAG laser of 2 J/10 ns is 107 photons/RF-pulse (108 photons/sec at 10 pps). We design to adopt a technique of laser circulation to increase the X-ray yield up to 109 photons/pulse (1010 photons/s). 50 MW X-band klystron and compact modulator have been constructed and now under tuning. The construction of the whole system has started. X-ray generation and medical application will be performed in the early next year.

  12. Band gaps of wurtzite Sc{sub x}Ga{sub 1−x}N alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tsui, H. C. L.; Moram, M. A. [Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Goff, L. E. [Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Rhode, S. K. [Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Pereira, S. [CICECO and Dept. Physics, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Beere, H. E.; Farrer, I.; Nicoll, C. A.; Ritchie, D. A. [Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

    2015-03-30

    Optical transmittance measurements on epitaxial, phase-pure, wurtzite-structure Sc{sub x}Ga{sub 1−x}N films with 0 ≤ x ≤ 0.26 showed that their direct optical band gaps increased from 3.33 eV to 3.89 eV with increasing x, in agreement with theory. These films contained I{sub 1}- and I{sub 2}-type stacking faults. However, the direct optical band gaps decreased from 3.37 eV to 3.26 eV for Sc{sub x}Ga{sub 1−x}N films, which additionally contained nanoscale lamellar inclusions of the zinc-blende phase, as revealed by aberration-corrected scanning transmission electron microscopy. Therefore, we conclude that the apparent reduction in Sc{sub x}Ga{sub 1−x}N band gaps with increasing x is an artefact resulting from the presence of nanoscale zinc-blende inclusions.

  13. High Power Test of an X-Band Slotted-IRIS Accelerator Structure at NLCTA

    International Nuclear Information System (INIS)

    Doebert, S.; Fandos, R.; Grudiev, A.; Heikkinen, S.; Rodriquez, J.A.; Taborelli, M.; Wuensch, W.; Adolphsen, Chris E.; Laurent, L.

    2007-01-01

    The CLIC study group at CERN has built two X-band HDS (hybrid damped structure) accelerating structures for high-power testing in NLCTA at SLAC. These accelerating structures are novel with respect to their rf- design and their fabrication technique. The eleven-cell constant impedance structures, one made out of copper and one out of molybdenum, are assembled from clamped high-speed milled quadrants. They feature the same heavy higher-order-mode damping as nominal CLIC structures achieved by slotted irises and radial damping waveguides for each cell. The X-band accelerators are exactly scaled versions of structures tested at 30 GHz in the CLIC test facility, CTF3. The results of the X-band tests are presented and compared to those at 30 GHz to determine frequency scaling, and are compared to the extensive copper data from the NLC structure development program to determine material dependence and make a basic validation of the HDS design

  14. Short-arc orbit determination using coherent X-band ranging data

    Science.gov (United States)

    Thurman, S. W.; Mcelrath, T. P.; Pollmeier, V. M.

    1992-01-01

    The use of X-band frequencies in ground-spacecraft and spacecraft-ground telecommunication links for current and future robotic interplanetary missions makes it possible to perform ranging measurements of greater accuracy than previously obtained. It is shown that ranging data of sufficient accuracy, when acquired from multiple stations, can sense the geocentric angular position of a distant spacecraft. The application of high-accuracy S/X-band and X-band ranging to orbit determination with relatively short data arcs is investigated in planetary approach and encounter scenarios. Actual trajectory solutions for the Ulysses spacecraft constructed from S/X-band ranging and Doppler data are presented; error covariance calculations are used to predict the performance of X-band ranging and Doppler data. The Ulysses trajectory solutions indicate that the aim point for the spacecraft's February 1992 Jupiter encounter was predicted to a geocentric accuracy of 0.20 to 0.23/microrad. Explicit modeling of range bias parameters for each station pass is shown to largely remove systematic ground system calibration errors and transmission media effects from the Ulysses range measurements, which would otherwise corrupt the angle finding capabilities of the data. The Ulysses solutions were found to be reasonably consistent with the theoretical results, which suggest that angular accuracies of 0.08 to 0.1/microrad are achievable with X-band ranging.

  15. Retrospective biodosimetry with small tooth enamel samples using K-Band and X-Band

    International Nuclear Information System (INIS)

    Gomez, Jorge A.; Kinoshita, Angela; Leonor, Sergio J.; Belmonte, Gustavo C.; Baffa, Oswaldo

    2011-01-01

    In an attempt to make the in vitro electron spin resonance (ESR) retrospective dosimetry of the tooth enamel a lesser invasive method, experiments using X-Band and K-Band were performed, aiming to determine conditions that could be used in cases of accidental exposures. First, a small prism from the enamel was removed and ground with an agate mortar and pestle until particles reach a diameter of approximately less than 0.5 mm. This enamel extraction process resulted in lower signal artifact compared with the direct enamel extraction performed with a diamond burr abrasion. The manual grinding of the enamel does not lead to any induced ESR signal artifact, whereas the use of a diamond burr at low speed produces a signal artifact equivalent to the dosimetric signal induced by a dose of 500 mGy of gamma irradiation. A mass of 25 mg of enamel was removed from a sound molar tooth previously irradiated in vitro with a dose of 100 mGy. This amount of enamel was enough to detect the dosimetric signal in a standard X-Band spectrometer. However using a K-Band spectrometer, samples mass between 5 and 10 mg were sufficient to obtain the same sensitivity. An overall evaluation of the uncertainties involved in the process in this and other dosimetric assessments performed at our laboratory indicates that it is possible at K-Band to estimate a 100 mGy dose with 25% accuracy. In addition, the use of K-Band also presented higher sensitivity and allowed the use of smaller sample mass in comparison with X-Band. Finally, the restoration process performed on a tooth after extraction of the 25 mg of enamel is described. This was conducted by dental treatment using photopolymerizable resin which enabled complete recovery of the tooth from the functional and aesthetic viewpoint showing that this procedure can be minimally invasive.

  16. Retrospective biodosimetry with small tooth enamel samples using K-Band and X-Band

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Jorge A. [Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto, Sao Paulo (Brazil); Kinoshita, Angela [Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto, Sao Paulo (Brazil); Universidade Sagrado Coracao - USC, 17011-160 Bauru, Sao Paulo (Brazil); Leonor, Sergio J. [Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto, Sao Paulo (Brazil); Belmonte, Gustavo C. [Universidade Sagrado Coracao - USC, 17011-160 Bauru, Sao Paulo (Brazil); Baffa, Oswaldo, E-mail: baffa@usp.br [Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto, Sao Paulo (Brazil)

    2011-09-15

    In an attempt to make the in vitro electron spin resonance (ESR) retrospective dosimetry of the tooth enamel a lesser invasive method, experiments using X-Band and K-Band were performed, aiming to determine conditions that could be used in cases of accidental exposures. First, a small prism from the enamel was removed and ground with an agate mortar and pestle until particles reach a diameter of approximately less than 0.5 mm. This enamel extraction process resulted in lower signal artifact compared with the direct enamel extraction performed with a diamond burr abrasion. The manual grinding of the enamel does not lead to any induced ESR signal artifact, whereas the use of a diamond burr at low speed produces a signal artifact equivalent to the dosimetric signal induced by a dose of 500 mGy of gamma irradiation. A mass of 25 mg of enamel was removed from a sound molar tooth previously irradiated in vitro with a dose of 100 mGy. This amount of enamel was enough to detect the dosimetric signal in a standard X-Band spectrometer. However using a K-Band spectrometer, samples mass between 5 and 10 mg were sufficient to obtain the same sensitivity. An overall evaluation of the uncertainties involved in the process in this and other dosimetric assessments performed at our laboratory indicates that it is possible at K-Band to estimate a 100 mGy dose with 25% accuracy. In addition, the use of K-Band also presented higher sensitivity and allowed the use of smaller sample mass in comparison with X-Band. Finally, the restoration process performed on a tooth after extraction of the 25 mg of enamel is described. This was conducted by dental treatment using photopolymerizable resin which enabled complete recovery of the tooth from the functional and aesthetic viewpoint showing that this procedure can be minimally invasive.

  17. Analysis on X-band structure breakdown at GLCTA

    International Nuclear Information System (INIS)

    Suehara, T.; Sanuki, T.; Komamiya, S.; Higo, T.; Hayano, H.; Terunuma, N.; Saeki, T.; Watanabe, K.; Hayakawa, A.; Tsukada, Y.

    2004-01-01

    We have built a new monitoring system for accelerator structure breakdown in the X-band high-gradient test facility at KEK (GLCTA: Global Linear Collider Test Accelerator). An X-band test structure KX01 (made by KEK) has been processed at GLCTA and we have been collecting data for about 3 months using this breakdown monitoring system. We describe overview of the monitoring system and preliminary result of breakdown analysis of the structure. (author)

  18. The electronic band structures of InNxAs1-x, InNxSb1-x and InAsxSb1-x alloys

    International Nuclear Information System (INIS)

    Mohammad, Rezek; Katircioglu, Senay

    2009-01-01

    The band gap bowings of InN x As 1-x , InN x Sb 1-x , and InAs x Sb 1-x alloys defined by the optimized lattice constants are investigated using empirical tight binding (ETB) method. The present ETB energy parameters which take the nearest neighbor interactions into account with sp 3 d 2 basis are determined to be sufficient to provide a typical feature for the band gap bowings of the alloys. The band gap bowing parameter is found to be relatively large in both InN x As 1-x and InN x Sb 1-x compared to InAs x Sb 1-x alloys. Moreover, the variation of the fundamental band gaps of InN x Sb 1-x alloys is sharper than that of InN x As 1-x alloys for small concentrations of N. Besides, a small amount of nitrogen is determined to be more effective in InN x Sb 1-x than in InN x As 1-x alloys to decrease the corresponding effective masses of the electrons around Γ points

  19. Tailoring group velocity by topology optimization

    DEFF Research Database (Denmark)

    Stainko, Roman; Sigmund, Ole

    2007-01-01

    The paper describes a systematic method for the tailoring of dispersion properties of slab-based photonic crystal waveguides. The method is based on the topology optimization method which consists in repeated finite element frequency domain analyses. The goal of the optimization process is to come...... up with slow light, zero group velocity dispersion photonic waveguides or photonic waveguides with tailored dispersion properties for dispersion compensation purposes. An example concerning the design of a wide bandwidth, constant low group velocity waveguide demonstrate the e±ciency of the method....

  20. The structure and band gap design of high Si doping level Ag1−xGa1−xSixSe2 (x=1/2)

    International Nuclear Information System (INIS)

    Zhang, Shiyan; Mei, Dajiang; Du, Xin; Lin, Zheshuai; Zhong, Junbo; Wu, Yuandong; Xu, Jingli

    2016-01-01

    Ag 1−x Ga 1−x Si x Se 2 solutions with high Si doping level (x=1/2) are considered and new compound AgGaSiSe 4 has been synthesized. It crystallizes in space group Aea2 and possesses very long axis of a=63.06(1)Å. The three-dimensional framework in AgGaSiSe 4 is composed of AgSe 3 trigonal planar units, AgSe 4 tetrahedra and MSe 4 (M=Si, Ga) tetrahedra. AgGaSiSe 4 is a congruently melting compound with the melt temperature of 759 °C. The diffuse reflectance measurements reveal the band gap of 2.63 eV in AgGaSiSe 4 and the value is 0.33 eV larger than that of Ag 3 Ga 3 SiSe 8 (2.30 eV). - Graphical abstract: The Ag 1−x Ga 1−x Si x Se 2 with high Si doping level (x=1/2) has been studied and the new compound AgGaSiSe 4 was synthesized for the first time. AgGaSiSe 4 crystallizes in a new structure type in space group Aea2 and adopts a three-dimensional framework consisting of AgSe 3 trigonal planar units, AgSe 4 tetrahedra and MSe 4 (M=Si, Ge) tetrahedra. Display Omitted - Highlights: • Study of Ag 1−x Ga 1−x Si x Se 2 with high Si doping level (x=1/2). • Successful synthesis of new compound named AgGaSiSe 4 . • AgGaSiSe 4 crystallizes in space group Aea2 and adopts a three-dimensional framework. • The energy band gap of AgGaSiSe 4 is enlarged compared with Ag 3 Ga 3 SiSe 8 .

  1. X-ray absorption and reflection as probes of the GaN conduction bands: Theory and experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lambrecht, W.R.L.; Rashkeev, S.N.; Segall, B. [Case Western Reserve Univ., Cleveland, OH (United States)] [and others

    1997-04-01

    X-ray absorption measurements are a well-known probe of the unoccupied states in a material. The same information can be obtained by using glancing angle X-ray reflectivity. In spite of several existing band structure calculations of the group III nitrides and previous optical studies in UV range, a direct probe of their conduction band densities of states is of interest. The authors performed a joint experimental and theoretical investigation using both of these experimental techniques for wurtzite GaN.

  2. Acute effects of elastic bands during the free-weight barbell back squat exercise on velocity, power, and force production.

    Science.gov (United States)

    Stevenson, Mark W; Warpeha, Joseph M; Dietz, Cal C; Giveans, Russell M; Erdman, Arthur G

    2010-11-01

    The use of elastic bands in resistance training has been reported to be effective in increasing performance-related parameters such as power, rate of force development (RFD), and velocity. The purpose of this study was to assess the following measures during the free-weight back squat exercise with and without elastic bands: peak and mean velocity in the eccentric and concentric phases (PV-E, PV-C, MV-E, MV-C), peak force (PF), peak power in the concentric phase, and RFD immediately before and after the zero-velocity point and in the concentric phase (RFDC). Twenty trained male volunteers (age = 26.0 ± 4.4 years) performed 3 sets of 3 repetitions of squats (at 55% one repetition maximum [1RM]) on 2 separate days: 1 day without bands and the other with bands in a randomized order. The added band force equaled 20% of the subjects' 55% 1RM. Two independent force platforms collected ground reaction force data, and a 9-camera motion capture system was used for displacement measurements. The results showed that PV-E and RFDC were significantly (p squats with elastic bands in terms of RFD. Practitioners concerned with improving RFD may want to consider incorporating this easily implemented training variation.

  3. High resolution Rayleigh wave group velocity tomography in North-China from ambient seismic noise

    International Nuclear Information System (INIS)

    Fang Lihua; Wu Jianping; Ding Zhifeng; Panza, G.F.

    2009-03-01

    This study presents the results of the Rayleigh wave group velocity tomography in North-China performed using ambient seismic noise observed at 190 broadband and 10 very broadband stations of the North-China Seismic Array. All available vertical component time-series for the 14 months span between January, 2007 and February, 2008 are cross-correlated to obtain empirical Rayleigh wave Green functions that are subsequently processed, with the multiple filter method, to isolate the group velocity dispersion curves of the fundamental mode of Rayleigh wave. Tomographic maps, with a grid spacing of 0.25 deg. x 0.25 deg., are computed at the periods of 4.5s, 12s, 20s, 28s. The maps at short periods reveal an evident lateral heterogeneity in the crust of North-China, quite well in agreement with known geological and tectonic features. The North China Basin is imaged as a broad low velocity area, while the Taihangshan and Yanshan uplifts and Ordos block are imaged as high velocity zones, and the Quaternary intermountain basins show up as small low-velocity anomalies. The group velocity contours at 4.5s, 12s and 20s are consistent with the Bouguer gravity anomalies measured in the area of the Taihangshan fault, that cuts through the lower crust at least. Most of the historical strong earthquakes (M≥6.0) are located where the tomographic maps show zones with moderate velocity gradient. (author)

  4. X-band RF power sources for accelerator applications

    International Nuclear Information System (INIS)

    Kirshner, Mark F.; Kowalczyk, Richard D.; Wilsen, Craig B.; True, Richard B.; Simpson, Ian T.; Wray, John T.

    2011-01-01

    The majority of medical and industrial linear accelerators (LINACs) in use today operate at S-band. To reduce size and weight, these systems are gradually migrating toward X-band. The new LINACs will require suitable RF components to power them. In anticipation of this market, L-3 Communications Electron Devices Division (EDD) has recently developed a suite of RF sources operating at 9.3 GHz to complement our existing S-band product line. (author)

  5. W-Band Transmission MeasurementS and X-Band Dielectric Properties Measurements for a Radome Material Sample

    Science.gov (United States)

    Cravey, Robin L.; Tiemsin, Pacita I.

    1997-01-01

    This paper describes measurements which were performed on a sample of radome material in the Electromagnetic Properties Measurements Laboratory (EPML). The purpose of the measurements described in this paper was to determine the one-way transmission loss through the flat panel of radome material for a frequency range of 84 to 94 GHz, for varying incidence angles. The panel, which was manufactured by Norton Performance Plastics Corporation, was provided to the EPML by TRW. The size of the panel is 40 in x 36 in x 0.422 in and consists of a foam material with one side coated with a smooth white coating (this side will be referred to as the front side). The dielectric properties of the foam material from the inside of the panel were also determined at X-band (8.2-12.4 GHz). The W-band free space measurements are presented first, followed by the X-band dielectric properties measurements.

  6. Valence Band Structure of InAs1-xBix and InSb1-xBix Alloy Semiconductors Calculated Using Valence Band Anticrossing Model

    Directory of Open Access Journals (Sweden)

    D. P. Samajdar

    2014-01-01

    Full Text Available The valence band anticrossing model has been used to calculate the heavy/light hole and spin-orbit split-off energies in InAs1-xBix and InSb1-xBix alloy systems. It is found that both the heavy/light hole, and spin-orbit split E+ levels move upwards in energy with an increase in Bi content in the alloy, whereas the split E− energy for the holes shows a reverse trend. The model is also used to calculate the reduction of band gap energy with an increase in Bi mole fraction. The calculated values of band gap variation agree well with the available experimental data.

  7. Control of group velocity by phase-changing collisions

    International Nuclear Information System (INIS)

    Goren, C.; Rosenbluh, M.; Wilson-Gordon, A.D.; Friedmann, H.

    2005-01-01

    We discuss the influence of phase-changing collisions on the group velocities in Doppler-broadened, cycling, degenerate two-level systems where F e =F g +1 and F g >0, interacting with pump and probe lasers, that exhibit electromagnetically induced absorption (EIA). Two model systems are considered: the N system where the pump and probe are polarized perpendicularly, and EIA is due to transfer of coherence (TOC), and the double two-level system (TLS) where both lasers have the same polarization, and EIA is due to transfer of population (TOP). For the case of Doppler-broadened EIA TOC, which occurs at low pump intensity, there is a switch from positive to negative dispersion and group velocity, as the rate of phase-changing collisions is increased. For the case of EIA TOP at low pump intensity, the dispersion and group velocity remain negative even when the collision rate is increased. Pressure-induced narrowing, accompanied by an increase in the magnitude of the negative dispersion and a decrease in the magnitude of the negative group velocity, occurs in both EIA TOC and EIA TOP, at low pump intensity. When the pump intensity is increased, a switch from negative to positive dispersion and group velocity, with increasing collision rate, also occurs in the double TLS system. However, the effect is far smaller than in the case of the N system at low pump intensity

  8. Group X

    Energy Technology Data Exchange (ETDEWEB)

    Fields, Susannah

    2007-08-16

    This project is currently under contract for research through the Department of Homeland Security until 2011. The group I was responsible for studying has to remain confidential so as not to affect the current project. All dates, reference links and authors, and other distinguishing characteristics of the original group have been removed from this report. All references to the name of this group or the individual splinter groups has been changed to 'Group X'. I have been collecting texts from a variety of sources intended for the use of recruiting and radicalizing members for Group X splinter groups for the purpose of researching the motivation and intent of leaders of those groups and their influence over the likelihood of group radicalization. This work included visiting many Group X websites to find information on splinter group leaders and finding their statements to new and old members. This proved difficult because the splinter groups of Group X are united in beliefs, but differ in public opinion. They are eager to tear each other down, prove their superiority, and yet remain anonymous. After a few weeks of intense searching, a list of eight recruiting texts and eight radicalizing texts from a variety of Group X leaders were compiled.

  9. CdS_xTe_1_-_x ternary semiconductors band gaps calculation using ground state and GW approximations

    International Nuclear Information System (INIS)

    Kheloufi, Nawal; Bouzid, Abderrazak

    2016-01-01

    We present band gap calculations of zinc-blende ternary CdS_xTe_1_-_x semiconductors within the standard DFT and quasiparticle calculations employing pseudopotential method. The DFT, the local density approximation (LDA) and the Generalized Gradient Approximation (GGA) based calculations have given very poor results compared to experimental data. The quasiparticle calculations have been investigated via the one-shot GW approximation. The present paper discuses and confirms the effect of inclusion of the semicore states in the cadmium (Cd) pseudopotential. The obtained GW quasiparticle band gap using Cd"+"2"0 pseudopotential has been improved compared to the obtained results from the available pseudopotential without the treatment of semicore states. Our DFT and quasiparticle band gap results are discussed and compared to the available theoretical calculations and experimental data. - Graphical abstract: Band gaps improvement concerning the binary and ternary alloys using the GW approximation and Cd"2"0"+ pseudopotential with others levels of approximations (the LDA and GGA approximation employing the Cd"1"2"+ and the LDA within Cd"2"0"+ pseudopotential). - Highlights: • The direct Γ- Γ and indirect Γ- X and Γ- L bands gaps show a nonlinear behavior when S content is enhanced. • The quasiparticle band gap result for the investigated semiconductors is improved using the GW approximation. • All CdS_xTe_1_-_x compounds in all compositions range from 0 to 1 are direct band gap semiconductors.

  10. A comparative cepstral based analysis of simulated and measured S-band and X-band radar Doppler spectra of human motion

    CSIR Research Space (South Africa)

    Van Eeden, WD

    2015-10-01

    Full Text Available targets. It is also shown that, whereas the motion of most body parts of a human target can be observed in the X-band data, only the main torso sway can be observed at S-band. This implies that X-band data is well suited to cepstrum based human motion...

  11. High gradient test of X-band accelerating structure at GLCTA

    International Nuclear Information System (INIS)

    Watanabe, K.; Higo, T.; Hayano, H.; Terunuma, N.; Saeki, T.; Kudo, N.; Sanuki, T.; Seuhara, T.

    2004-01-01

    GLCTA (Global Linear Collider Test Accelerator) is the high power test facility for X-band acceleration. We have installed an X-band 60cm structure in April 2004 and have been processing it for more than 3 months. Now it is under test on long-term operation. We report here the installation process and high power test result to date. (author)

  12. Evaluation of band alignment of α-Ga2O3/α-(Al x Ga1‑ x )2O3 heterostructures by X-ray photoelectron spectroscopy

    Science.gov (United States)

    Uchida, Takayuki; Jinno, Riena; Takemoto, Shu; Kaneko, Kentaro; Fujita, Shizuo

    2018-04-01

    The band alignment at an α-Ga2O3/α-(Al x Ga1‑ x )2O3 heterointerface, with different Al compositions (x), grown on a c-plane sapphire substrate was evaluated by X-ray photoelectron spectroscopy. The experimental results show that the heterointerface has the type-I band discontinuity with the valence band offsets of 0.090, 0.12, and 0.14 eV, and the conduction band offsets of 0.34, 0.79, and 1.87 eV, for x values of 0.1, 0.4, and 0.8, respectively. The small band offset for the valence band is attributed to the fact that the valence band of oxides is constituted by the localized O 2p level, which is dominated by the nature of oxygen atoms. The type-I band discontinuity is desirable for a variety of heterostructure devices.

  13. X-band klystrons for Japan Linear Collider

    International Nuclear Information System (INIS)

    Mizuno, H.; Odagiri, J.; Higo, T.; Yonezawa, H.; Yamaguchi, N.

    1992-01-01

    To achieve the acceleration gradient of 100 MeV/m necessary for the future linear collider in X-band, an RF power source which could produce more than 100 MW peak power with the pulse duration of 500 nsec is needed even with the factor 4 RF pulse compression system. As the first step for the development of the 100 MW class klystrons in X-band (11.424 GHz), a 30 MW class klystron named XB-50K was tested several times since 1990. XB-50K was tested up to the peak power of 18 MW with the pulse duration of 100 ns. A new 100 MW class klystron named XB-72K was designed and fabricated. Some test results of this klystron are reported. (Author) 9 refs., 3 figs., 2 tabs

  14. Realization of an X-Band RF System for LCLS

    CERN Document Server

    McIntosh, Peter; Brooks, William; Emma, Paul; Rago, Carl

    2005-01-01

    A single X-band (11.424 GHz) accelerating structure is to be incorporated in the LCLS Linac design to linearize the energy-time correlation (or gradient) across each bunch, features which originate in the preceding accelerating structures (L0 and L1). This harmonic RF system will operate near the negative RF crest to decelerate the beam, reducing these non-linear components of the correlation, providing a more efficient compression in the downstream bunch compressor chicanes (BC1 and BC2). These non-linear correlation components, if allowed to grow, would lead to Coherent Synchrotron Radiation (CSR) instabilities in the chicanes, effectively destroying the coherence of the photon radiation in the main LCLS undulator. The many years devoted at SLAC in the development of X-band RF components for the NLC/JLC linear collider project, has enabled the technical and financial realization of such an RF system for LCLS. This paper details the requirements for the X-band system and the proposed scheme planned for achie...

  15. The structure and band gap design of high Si doping level Ag{sub 1−x}Ga{sub 1−x}Si{sub x}Se{sub 2} (x=1/2)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shiyan [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Mei, Dajiang, E-mail: meidajiang718@pku.edu.cn [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Du, Xin [Beijing National Laboratory for Molecular Sciences and State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Lin, Zheshuai [Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Chinese Academy of Sciences, Beijing 100190 (China); Zhong, Junbo [Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan, College of Chemistry and Pharmaceutical Engineering, Sichuan University of Science and Engineering, Zigong 643000 (China); Wu, Yuandong, E-mail: wuyuandong2013@outlook.com [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Xu, Jingli [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China)

    2016-06-15

    Ag{sub 1−x}Ga{sub 1−x}Si{sub x}Se{sub 2} solutions with high Si doping level (x=1/2) are considered and new compound AgGaSiSe{sub 4} has been synthesized. It crystallizes in space group Aea2 and possesses very long axis of a=63.06(1)Å. The three-dimensional framework in AgGaSiSe{sub 4} is composed of AgSe{sub 3} trigonal planar units, AgSe{sub 4} tetrahedra and MSe{sub 4}(M=Si, Ga) tetrahedra. AgGaSiSe{sub 4} is a congruently melting compound with the melt temperature of 759 °C. The diffuse reflectance measurements reveal the band gap of 2.63 eV in AgGaSiSe{sub 4} and the value is 0.33 eV larger than that of Ag{sub 3}Ga{sub 3}SiSe{sub 8} (2.30 eV). - Graphical abstract: The Ag{sub 1−x}Ga{sub 1−x}Si{sub x}Se{sub 2} with high Si doping level (x=1/2) has been studied and the new compound AgGaSiSe{sub 4} was synthesized for the first time. AgGaSiSe{sub 4} crystallizes in a new structure type in space group Aea2 and adopts a three-dimensional framework consisting of AgSe{sub 3} trigonal planar units, AgSe{sub 4} tetrahedra and MSe{sub 4} (M=Si, Ge) tetrahedra. Display Omitted - Highlights: • Study of Ag{sub 1−x}Ga{sub 1−x}Si{sub x}Se{sub 2} with high Si doping level (x=1/2). • Successful synthesis of new compound named AgGaSiSe{sub 4}. • AgGaSiSe{sub 4} crystallizes in space group Aea2 and adopts a three-dimensional framework. • The energy band gap of AgGaSiSe{sub 4} is enlarged compared with Ag{sub 3}Ga{sub 3}SiSe{sub 8}.

  16. Anomalous band-gap bowing of AlN1−xPx alloy

    International Nuclear Information System (INIS)

    Winiarski, M.J.; Polak, M.; Scharoch, P.

    2013-01-01

    Highlights: •Structural and electronic properties of AlN 1−x P x from first principles. •The supercell and the virtual crystall approximation methods applied and compared. •Anomalously high band-gap bowing found. •Similarities of band-gap behavior to that in BN 1−x P x noticed. •Performance of MBJLDA with the pseudopotential approach discussed. -- Abstract: Electronic structure of zinc blende AlN 1−x P x alloy has been calculated from first principles. Structural optimization has been performed within the framework of LDA and the band-gaps calculated with the modified Becke–Jonson (MBJLDA) method. Two approaches have been examined: the virtual crystal approximation (VCA) and the supercell-based calculations (SC). The composition dependence of the lattice parameter obtained from the SC obeys Vegard’s law whereas the volume optimization in the VCA leads to an anomalous bowing of the lattice constant. A strong correlation between the band-gaps and the structural parameter in the VCA method has been observed. On the other hand, in the SC method the supercell size and atoms arrangement (clustered vs. uniform) appear to have a great influence on the computed band-gaps. In particular, an anomalously big band-gap bowing has been found in the case of a clustered configuration with relaxed geometry. Based on the performed tests and obtained results some general features of MBJLDA are discussed and its performance for similar systems predicted

  17. An attenuation Layer for Electromagnetic Shielding in X- Band Frequency

    Directory of Open Access Journals (Sweden)

    Vida Zaroushani

    2015-06-01

    Full Text Available Uncontrolled exposure to X-band frequency leads to health damage. One of the principles of radiation protection is shielding. But, conventional shielding materials have disadvantages. Therefore, studies of novel materials, as an alternative to conventional shielding materials, are required to obtain new electromagnetic shielding material. Therefore, this study investigated the electromagnetic shielding of two component epoxy thermosetting resin for the X - band frequency with workplace approach. Two components of epoxy resin mixed according to manufacturing instruction with the weight ratio that was 100:10 .Epoxy plates fabricated in three different thicknesses (2, 4 and 6mm and shielding effectiveness measured by Vector Network Analyzer. Then, shielding effectiveness measured by the scattering parameters.The results showed that 6mm thickness of epoxy had the highest and 2mm had the lowest average of shielding effectiveness in X-band frequency that is 4.48 and 1.9 dB, respectively. Also, shielding effectiveness increased by increasing the thickness. But this increasing is useful up to 4mm. Percentage shielding effectiveness of attenuation for 6, 4 and 2mm thicknesses is 64.35%, 63.31% and 35.40%. Also, attenuation values for 4mm and 6mm thicknesses at 8.53 GHz and 8.52 GHz frequency are 77.15% and 82.95%, respectively, and can be used as favourite shields for the above frequency. 4mm-Epoxy is a suitable candidate for shielding application in X-band frequency range but, in the lower section, 6mm thickness is recommended. Finely, the shielding matrix can be used for selecting the proper thickness for electromagnetic shielding in X- Band frequency.

  18. Tropical-forest biomass estimation at X-Band from the spaceborne TanDEM-X interferometer

    Science.gov (United States)

    R. Treuhaft; F. Goncalves; J.R. dos Santos; M. Keller; M. Palace; S.N. Madsen; F. Sullivan; P.M.L.A. Graca

    2014-01-01

    This letter reports the sensitivity of X-band interferometric synthetic aperture radar (InSAR) data from the first dual-spacecraft radar interferometer, TanDEM-X, to variations in tropical-forest aboveground biomass (AGB). It also reports the first tropical-forest AGB estimates fromTanDEM-X data. Tropical forests account for...

  19. Thermal evolution of the band edges of 6H-SiC: X-ray methods compared to the optical band gap

    International Nuclear Information System (INIS)

    Miedema, P.S.; Beye, M.; Könnecke, R.; Schiwietz, G.; Föhlisch, A.

    2014-01-01

    Highlights: • Conduction band minima (CBM) of 6H-SiC are estimated with Si 2p XAS. • Valence band maxima (VBM) of 6H-SiC are estimated with non-resonant Si 2p XES. • Temperature-dependent VBM and CBM of 6H-SiC show asymmetric band gap closing. • XAS, XES and RIXS band gap estimates are compared with the optical band gap. • XAS + XES versus optical band gap provides core-excitonic screening energies. - Abstract: The band gap of semiconductors like silicon and silicon carbide (SiC) is the key for their device properties. In this research, the band gap of 6H-SiC and its temperature dependence were analyzed with silicon 2p X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES) and resonant inelastic X-ray scattering (RIXS) allowing for a separate analysis of the conduction-band minimum (CBM) and valence-band maximum (VBM) components of the band gap. The temperature-dependent asymmetric band gap shrinking of 6H-SiC was determined with a valence-band slope of +2.45 × 10 −4 eV/K and a conduction-band slope of −1.334 × 10 −4 eV/K. The apparent asymmetry, e.g., that two thirds of the band-gap shrinking with increasing temperature is due to the VBM evolution in 6H-SiC, is similar to the asymmetry obtained for pure silicon before. The overall band gap temperature-dependence determined with XAS and non-resonant XES is compared to temperature-dependent optical studies. The core-excitonic binding energy appearing in the Si 2p XAS is extracted as the main difference. In addition, the energy loss of the onset of the first band in RIXS yields to values similar to the optical band gap over the tested temperature range

  20. Determination of band-structure parameters of Pbsub(1-x)Snsub(x)Te narrow-gap semiconductor from infrared Faraday rotation

    International Nuclear Information System (INIS)

    Sizov, F.F.; Lashkarev, G.V.; Martynchuk, E.K.

    1977-01-01

    The temeprature dependences of Faraday rotation in Pbsub(1-x)Snsub(x)Te of p type with the hole density 3x10 16 -2.2x10 18 cm -3 are studied in the range 40-370 K and in the spectral interval 4-16 μm. The analysis of interband Faraday rotation confirms a conclusion made by the authors earlier that the g factor for the c band (gsub(c)) is positive, for the v band (gsub(v))-negative and that [gsub(c)] > [gsub(v)]. The temperature dependences of carrier effective masses are investigated on the basis of the two-band model. It is demonstrated that for T < 200 K the Faraday effective mass of holes near the ceiling of the valency band varies in direct proportion to the width of the forbidden band. The temperature increase of the Faraday effective mass of current carriers, which is faster than that of the effective electron mass, is discovered, and this is related to the effect of the heavy hole band

  1. Distortion of absorption-line velocity curves due to x-ray heating in x-ray binaries

    International Nuclear Information System (INIS)

    Milgrom, M.

    1976-01-01

    The effects of X-ray heating on the measured absorption line velocities, in X-ray binaries with low X-rays to optical luminosities ratio are considered. These effects may be appreciable even for such binaries where the effect of X-ray heating on the light-curve is negligible. The effects are studied qualitatively and suggest possible ways to partially eliminate the systematic errors introduced by them. The individual systems Cyg x-1 and SMC x-1 are treated and the results of numerical calculations are presented for them. For Cyg x-1 it is found that the effect is detectable during the X-ray 'high' state in all regions of the spectrum. During the 'low' state it may be important in the red region of the spectrum. The results for the case in which soft X-ray fluxes (E < or approximately .4 keV, suggested by theoretical models) are present are also given. For SMC x-1 a strong effect for Hα, Hβ, Hγ had been found. This effect may be responsible for the observed variable velocity curve. We also find for SMC x-1 that the average X-ray intensity falling on the primary must be considerably smaller than what is derived from the detected flux, or else the effect is too large. (author)

  2. Performance of high-resolution X-band radar for rainfall measurement in The Netherlands

    Directory of Open Access Journals (Sweden)

    C. Z. van de Beek

    2010-02-01

    Full Text Available This study presents an analysis of 195 rainfall events gathered with the X-band weather radar SOLIDAR and a tipping bucket rain gauge network near Delft, The Netherlands, between May 1993 and April 1994. The aim of this paper is to present a thorough analysis of a climatological dataset using a high spatial (120 m and temporal (16 s resolution X-band radar. This makes it a study of the potential for high-resolution rainfall measurements with non-polarimetric X-band radar over flat terrain. An appropriate radar reflectivity – rain rate relation is derived from measurements of raindrop size distributions and compared with radar – rain gauge data. The radar calibration is assessed using a long-term comparison of rain gauge measurements with corresponding radar reflectivities as well as by analyzing the evolution of the stability of ground clutter areas over time. Three different methods for ground clutter correction as well as the effectiveness of forward and backward attenuation correction algorithms have been studied. Five individual rainfall events are discussed in detail to illustrate the strengths and weaknesses of high-resolution X-band radar and the effectiveness of the presented correction methods. X-band radar is found to be able to measure the space-time variation of rainfall at high resolution, far greater than what can be achieved by rain gauge networks or a typical operational C-band weather radar. On the other hand, SOLIDAR can suffer from receiver saturation, wet radome attenuation as well as signal loss along the path. During very strong convective situations the signal can even be lost completely. In combination with several rain gauges for quality control, high resolution X-band radar is considered to be suitable for rainfall monitoring over relatively small (urban catchments. These results offer great prospects for the new high resolution polarimetric doppler X-band radar IDRA.

  3. Determination of the surface band bending in InxGa1−xN films by hard x-ray photoemission spectroscopy

    Directory of Open Access Journals (Sweden)

    Mickael Lozac'h, Shigenori Ueda, Shitao Liu, Hideki Yoshikawa, Sang Liwen, Xinqiang Wang, Bo Shen, Kazuaki Sakoda, Keisuke Kobayashi and Masatomo Sumiya

    2013-01-01

    Full Text Available Core-level and valence band spectra of InxGa1−xN films were measured using hard x-ray photoemission spectroscopy (HX-PES. Fine structure, caused by the coupling of the localized Ga 3d and In 4d with N 2s states, was experimentally observed in the films. Because of the large detection depth of HX-PES (~20 nm, the spectra contain both surface and bulk information due to the surface band bending. The InxGa1−xN films (x = 0–0.21 exhibited upward surface band bending, and the valence band maximum was shifted to lower binding energy when the mole fraction of InN was increased. On the other hand, downward surface band bending was confirmed for an InN film with low carrier density despite its n-type conduction. Although the Fermi level (EF near the surface of the InN film was detected inside the conduction band as reported previously, it can be concluded that EF in the bulk of the film must be located in the band gap below the conduction band minimum.

  4. Valence Band Structure of InAs1−xBix and InSb1−xBix Alloy Semiconductors Calculated Using Valence Band Anticrossing Model

    Science.gov (United States)

    Samajdar, D. P.; Dhar, S.

    2014-01-01

    The valence band anticrossing model has been used to calculate the heavy/light hole and spin-orbit split-off energies in InAs1−xBix and InSb1−xBix alloy systems. It is found that both the heavy/light hole, and spin-orbit split E + levels move upwards in energy with an increase in Bi content in the alloy, whereas the split E − energy for the holes shows a reverse trend. The model is also used to calculate the reduction of band gap energy with an increase in Bi mole fraction. The calculated values of band gap variation agree well with the available experimental data. PMID:24592181

  5. Comparison of high group velocity accelerating structures

    International Nuclear Information System (INIS)

    Farkas, Z.D.; Wilson, P.B.

    1987-02-01

    It is well known that waveguides with no perturbations have phase velocities greater than the velocity of light c. If the waveguide dimensions are chosen so that the phase velocity is only moderately greater than c, only small perturbations are required to reduce the phase velocity to be synchronous with a high energy particle bunch. Such a lightly loaded accelerator structure will have smaller longitudinal and transverse wake potentials and hence will lead to lower emittance growth in an accelerated beam. Since these structures are lightly loaded, their group velocities are only slightly less than c and not in the order of 0.01c, as is the case for the standard disk-loaded structures. To ascertain that the peak and average power requirements for these structures are not prohibitive, we examine the elastance and the Q for several traveling wave structures: phase slip structures, bellows-like structures, and lightly loaded disk-loaded structures

  6. X-Band Linac Beam-Line for Medical Compton Scattering X-Ray Source

    CERN Document Server

    Dobashi, Katsuhiro; Ebina, Futaro; Fukasawa, Atsushi; Hayano, Hitoshi; Higo, Toshiyasu; Kaneyasu, Tatsuo; Ogino, Haruyuki; Sakamoto, Fumito; Uesaka, Mitsuru; Urakawa, Junji; Yamamoto, Tomohiko

    2005-01-01

    Compton scattering hard X-ray source for 10~80 keV are under construction using the X-band (11.424 GHz) electron linear accelerator and YAG laser at Nuclear Engineering Research laboratory, University of Tokyo. This work is a part of the national project on the development of advanced compact medical accelerators in Japan. National Institute for Radiological Science is the host institute and U. Tokyo and KEK are working for the X-ray source. Main advantage is to produce tunable monochromatic hard ( 10-80

  7. Ballistic-electron-emission spectroscopy of AlxGa1-xAs/GaAs heterostructures: Conduction-band offsets, transport mechanisms, and band-structure effects

    International Nuclear Information System (INIS)

    OShea, J.J.; Brazel, E.G.; Rubin, M.E.; Bhargava, S.; Chin, M.A.; Narayanamurti, V.

    1997-01-01

    We report an extensive investigation of semiconductor band-structure effects in single-barrier Al x Ga 1-x As/GaAs heterostructures using ballistic-electron-emission spectroscopy (BEES). The transport mechanisms in these single-barrier structures were studied systematically as a function of temperature and Al composition over the full compositional range (0≤x≤1). The initial (Γ) BEES thresholds for Al x Ga 1-x As single barriers with 0≤x≤0.42 were extracted using a model which includes the complete transmission probability of the metal-semiconductor interface and the semiconductor heterostructure. Band offsets measured by BEES are in good agreement with previous measurements by other techniques which demonstrates the accuracy of this technique. BEES measurements at 77 K give the same band-offset values as at room temperature. When a reverse bias is applied to the heterostructures, the BEES thresholds shift to lower voltages in good agreement with the expected bias-induced band-bending. In the indirect band-gap regime (x>0.45), spectra show a weak ballistic-electron-emission microscopy current contribution due to intervalley scattering through Al x Ga 1-x As X valley states. Low-temperature spectra show a marked reduction in this intervalley current component, indicating that intervalley phonon scattering at the GaAs/Al x Ga 1-x As interface produces a significant fraction of thisX valley current. A comparison of the BEES thresholds with the expected composition dependence of the Al x Ga 1-x As Γ, L, and X points yields good agreement over the entire composition range. copyright 1997 The American Physical Society

  8. Huge operation by energy gap of novel narrow band gap Tl1-x In1-x B x Se2 (B = Si, Ge): DFT, x-ray emission and photoconductivity studies

    Science.gov (United States)

    Piasecki, M.; Myronchuk, G. L.; Zamurueva, O. V.; Khyzhun, O. Y.; Parasyuk, O. V.; Fedorchuk, A. O.; Albassam, A.; El-Naggar, A. M.; Kityk, I. V.

    2016-02-01

    It is shown that narrow band gap semiconductors Tl1-x In1-x GexSe2 are able effectively to vary the values of the energy gap. DFT simulations of the principal bands during the cationic substitutions is done. Changes of carrier transport features is explored. Relation with the changes of the near the surface states is explored . Comparison on a common energy scale of the x-ray emission Se Kβ 2 bands, representing energy distribution of the Se 4p states, indicates that these states contribute preliminary to the top of the valence band. The temperature dependence of electrical conductivity and spectral dependence photoconductivity for the Tl1-x In1-x Ge x Se2 and Tl1-x In1-x Si x Se2 single crystals were explored and compared with previously reported Tl1-x In1-x Sn x Se2. Based on our investigations, a model of centre re-charging is proposed. Contrary to other investigated crystals in Tl1-x In1-x Ge x Se2 single crystals for x = 0.1 we observe extraordinarily enormous photoresponse, which exceed more than nine times the dark current. X-ray photoelectron core-level and valence-band spectra for pristine and Ar+-ion irradiated surfaces of Tl1-x In1-x GexSe2 (x = 0.1 and 0.2) single crystals have been studied. These results indicate that the relatively low hygroscopicity of the studied single crystals is typical for the Tl1-x In1-x Ge x Se2 crystals, a property that is very important for handling these quaternary selenides as infrared materials operating at ambient conditions.

  9. S-band and X-band integrated PWT photoelectron linacs

    International Nuclear Information System (INIS)

    Yu, D.; Newsham, D.; Zeng, J.; Rosenzweig, J.

    2001-01-01

    A compact high-energy injector, which has been developed by DULY Research Inc., will have wide scientific, industrial, and medical applications. The new photoelectron injector integrates the photocathode directly into a multicell linear accelerator. By focusing the beam with solenoids or permanent magnets, and producing high current with low emittance, high brightness and low energy spread are achieved. In addition to providing a small footprint and improved beam quality in an integrated structure, the compact system considerably simplifies external subsystems required to operate the photoelectron linac, including rf power transport, beam focusing, vacuum and cooling. The photoelectron linac employs an innovative Plane-Wave-Transformer (PWT) design, which provides strong cell-to-cell coupling, relaxes manufacturing tolerances and facilitates the attachment of external ports to the compact structure with minimal field interference. DULY Research Inc. under the support of the DOE Small Business Innovation Research (SBIR) program, has developed, constructed and installed a 20-MeV, S-band compact electron source at UCLA. Cold test results for this device are presented. DULY Research is also actively engaged in the development of an X-band photoelectron linear accelerator in a SBIR project. When completed, the higher frequency structure will be approximately three times smaller. Design considerations for this device are discussed following the S-band cold test results

  10. CdS{sub x}Te{sub 1-x} ternary semiconductors band gaps calculation using ground state and GW approximations

    Energy Technology Data Exchange (ETDEWEB)

    Kheloufi, Nawal; Bouzid, Abderrazak, E-mail: a_bouzid34@hotmail.com

    2016-06-25

    We present band gap calculations of zinc-blende ternary CdS{sub x}Te{sub 1-x} semiconductors within the standard DFT and quasiparticle calculations employing pseudopotential method. The DFT, the local density approximation (LDA) and the Generalized Gradient Approximation (GGA) based calculations have given very poor results compared to experimental data. The quasiparticle calculations have been investigated via the one-shot GW approximation. The present paper discuses and confirms the effect of inclusion of the semicore states in the cadmium (Cd) pseudopotential. The obtained GW quasiparticle band gap using Cd{sup +20} pseudopotential has been improved compared to the obtained results from the available pseudopotential without the treatment of semicore states. Our DFT and quasiparticle band gap results are discussed and compared to the available theoretical calculations and experimental data. - Graphical abstract: Band gaps improvement concerning the binary and ternary alloys using the GW approximation and Cd{sup 20+} pseudopotential with others levels of approximations (the LDA and GGA approximation employing the Cd{sup 12+} and the LDA within Cd{sup 20+} pseudopotential). - Highlights: • The direct Γ- Γ and indirect Γ- X and Γ- L bands gaps show a nonlinear behavior when S content is enhanced. • The quasiparticle band gap result for the investigated semiconductors is improved using the GW approximation. • All CdS{sub x}Te{sub 1-x} compounds in all compositions range from 0 to 1 are direct band gap semiconductors.

  11. The development for C-band whole sealed vacuum accelerating tuber

    International Nuclear Information System (INIS)

    Zhou Wenzhen; Zhang Xiangyang; Ding Shulin; Hu Jinquan; Yang Zhenyuan

    1999-01-01

    S-Band standing wave electron linacs have got wide-ranging application for industry nondestructive testing and formed varied kinds of products. X-band electron linac for NDT has been developed by Schonberg Company USA in 1985. Because of bigger structure of S-band linac and difficult machining of X-Band linac, an C-band portable linac for NDT has been developed in CIAE at present, a whole sealed vacuum accelerating tuber will be given here. It consists of 4 cavities, the phase velocity of the first two cavities is 0.5 and 0.9, respectively, and that of the second two cavities is 1. The high power testing proved that the design of the accelerating tuber is good for 1.5 MeV electron linac for NDT

  12. CAMEX-4 MOBILE X-BAND POLARIMETRIC WEATHER RADAR V1

    Data.gov (United States)

    National Aeronautics and Space Administration — Mobile X-band Polarimetric Weather Radar on Wheels (X-POW)is a Doppler scanning radar operating at 9.3 GHz.with horizontal and vertical polarization. Used for...

  13. Group Velocity for Leaky Waves

    Science.gov (United States)

    Rzeznik, Andrew; Chumakova, Lyubov; Rosales, Rodolfo

    2017-11-01

    In many linear dispersive/conservative wave problems one considers solutions in an infinite medium which is uniform everywhere except for a bounded region. In general, localized inhomogeneities of the medium cause partial internal reflection, and some waves leak out of the domain. Often one only desires the solution in the inhomogeneous region, with the exterior accounted for by radiation boundary conditions. Formulating such conditions requires definition of the direction of energy propagation for leaky waves in multiple dimensions. In uniform media such waves have the form exp (d . x + st) where d and s are complex and related by a dispersion relation. A complex s is required since these waves decay via radiation to infinity, even though the medium is conservative. We present a modified form of Whitham's Averaged Lagrangian Theory along with modulation theory to extend the classical idea of group velocity to leaky waves. This allows for solving on the bounded region by representing the waves as a linear combination of leaky modes, each exponentially decaying in time. This presentation is part of a joint project, and applications of these results to example GFD problems will be presented by L. Chumakova in the talk ``Leaky GFD Problems''. This work is partially supported by NSF Grants DMS-1614043, DMS-1719637, and 1122374, and by the Hertz Foundation.

  14. Mechanical Design of Military Communication Satellite X-band PCM

    Directory of Open Access Journals (Sweden)

    Hyung Je Woo

    1998-12-01

    Full Text Available Before an actual military communications satellite is designed and constructed, a feasibility study should take place. The basic functions of such system can be observed and demonstrated in an X-Band payload simulator. For this purpose a Payload Concept Model (PCM for X-Band payload subsystem has been developed to simulate the workings of an actual military communications payload. This paper explains and illustrates the mechanical design, manufacture, and integration of the PCM. Basic RF tests also have been performed in order to verify the design requirement of the system. The results demonstrate successful development of the PCM and operation without RF losses.

  15. Nature of the fundamental band gap in GaNxP1-x alloys

    International Nuclear Information System (INIS)

    Shan, W.; Walukiewicz, W.; Yu, K. M.; Wu, J.; Ager, J. W. III; Haller, E. E.; Xin, H. P.; Tu, C. W.

    2000-01-01

    The optical properties of GaN x P 1-x alloys (0.007≤x≤0.031) grown by gas-source molecular-beam epitaxy have been studied. An absorption edge appears in GaN x P 1-x at energy below the indirect Γ V -X C transition in GaP, and the absorption edge shifts to lower energy with increasing N concentration. Strong photomodulation signals associated with the absorption edges in GaN x P 1-x indicate that a direct fundamental optical transition is taking place, revealing that the fundamental band gap has changed from indirect to direct. This N-induced transformation from indirect to direct band gap is explained in terms of an interaction between the highly localized nitrogen states and the extended states at the Γ conduction-band minimum. (c) 2000 American Institute of Physics

  16. Left regular bands of groups of left quotients

    International Nuclear Information System (INIS)

    El-Qallali, A.

    1988-10-01

    A semigroup S which has a left regular band of groups as a semigroup of left quotients is shown to be the semigroup which is a left regular band of right reversible cancellative semigroups. An alternative characterization is provided by using spinned products. These results are applied to the case where S is a superabundant whose set of idempotents forms a left normal band. (author). 13 refs

  17. AlxGa1--xN/GaN band offsets determined by deep-level emission

    International Nuclear Information System (INIS)

    Hang, D. R.; Chen, C. H.; Chen, Y. F.; Jiang, H. X.; Lin, J. Y.

    2001-01-01

    We present studies of the compositional dependence of the optical properties of Al x Ga 1-x N(0 x Ga 1-x N. As aluminum concentration increases, the color of the band changes from yellow (2.2 eV) to blue (2.6 eV). The shift was less than that of the band gap. Together with previously published studies, it implies that the deep acceptor level is pinned to a common reference level to both materials, thus the deep level responsible for the yellow emission is used as a common reference level to determine the band alignment in Al x Ga 1-x N/GaN heterojunctions. Combining with the near-band-edge modulation spectra, the estimated ratio of conduction-to-valence band discontinuity is 65:35. Our results are close to the values obtained from PL measurements on Al 0.14 Ga 0.86 N/GaN quantum wells and those calculated by linear muffin-tin orbital method and linearized augmented plane wave method. copyright 2001 American Institute of Physics

  18. Intercomparison of attenuation correction algorithms for single-polarized X-band radars

    Science.gov (United States)

    Lengfeld, K.; Berenguer, M.; Sempere Torres, D.

    2018-03-01

    Attenuation due to liquid water is one of the largest uncertainties in radar observations. The effects of attenuation are generally inversely proportional to the wavelength, i.e. observations from X-band radars are more affected by attenuation than those from C- or S-band systems. On the other hand, X-band radars can measure precipitation fields in higher temporal and spatial resolution and are more mobile and easier to install due to smaller antennas. A first algorithm for attenuation correction in single-polarized systems was proposed by Hitschfeld and Bordan (1954) (HB), but it gets unstable in case of small errors (e.g. in the radar calibration) and strong attenuation. Therefore, methods have been developed that restrict attenuation correction to keep the algorithm stable, using e.g. surface echoes (for space-borne radars) and mountain returns (for ground radars) as a final value (FV), or adjustment of the radar constant (C) or the coefficient α. In the absence of mountain returns, measurements from C- or S-band radars can be used to constrain the correction. All these methods are based on the statistical relation between reflectivity and specific attenuation. Another way to correct for attenuation in X-band radar observations is to use additional information from less attenuated radar systems, e.g. the ratio between X-band and C- or S-band radar measurements. Lengfeld et al. (2016) proposed such a method based isotonic regression of the ratio between X- and C-band radar observations along the radar beam. This study presents a comparison of the original HB algorithm and three algorithms based on the statistical relation between reflectivity and specific attenuation as well as two methods implementing additional information of C-band radar measurements. Their performance in two precipitation events (one mainly convective and the other one stratiform) shows that a restriction of the HB is necessary to avoid instabilities. A comparison with vertically pointing

  19. Scaling of x-ray emission and ion velocity in laser produced Cu ...

    Indian Academy of Sciences (India)

    Laser plasma; x-ray emission; conversion efficiency; ion velocities. ... fits from this kind of optimization studies are in the fields of x-ray lithography, x-ray lasers etc. .... formula between the x-ray conversion rate versus different parameters of the ...

  20. Analysis of X-Band Very High Resolution Persistent Scatterer Interferometry Data Over Urban Areas

    Science.gov (United States)

    Crosetto, M.; Monserrat, O.; Cuevas-González, M.; Devanthéry, N.; Crippa, B.

    2013-04-01

    Persistent Scatterer Interferometry (PSI) is a satellite-based Synthetic Aperture Radar (SAR) remote sensing technique used to measure and monitor land deformation from a stack of interferometric SAR images. This work concerns X-band PSI and, in particular, PSI based on very high resolution (VHR) StripMap CosmoSkyMed and TerraSAR-X SAR imagery. In fact, it mainly focuses on the technical aspects of deformation measurement and monitoring over urban areas. A key technical aspect analysed in this paper is the thermal expansion component of PSI observations, which is a result of temperature differences in the imaged area between SAR acquisitions. This component of PSI observations is particularly important in the urban environment. This is an interesting feature of PSI, which can be surely used to illustrate the high sensitivity of X-band PSI to very subtle displacements. Thermal expansion can have a strong impact on the PSI products, especially on the deformation velocity maps and deformation time series, if not properly handled during the PSI data processing and analysis, and a comprehensive discussion of this aspect will be provided in this paper. The importance of thermal expansion is related to the fact that the PSI analyses are often performed using limited stacks of images, which may cover a limited time period, e.g. several months only. These two factors (limited number of images and short period) make the impact of a non-modelled thermal expansion particularly critical. This issue will be illustrated considering different case studies based on TerraSAR-X and CosmoSkyMed PSI data. Besides, an extended PSI model which alleviates this problem will be described and case studies from the Barcelona metropolitan area will demonstrate the effectiveness of the proposed strategy.

  1. ANALYSIS OF X-BAND VERY HIGH RESOLUTION PERSISTENT SCATTERER INTERFEROMETRY DATA OVER URBAN AREAS

    Directory of Open Access Journals (Sweden)

    M. Crosetto

    2013-04-01

    Full Text Available Persistent Scatterer Interferometry (PSI is a satellite-based Synthetic Aperture Radar (SAR remote sensing technique used to measure and monitor land deformation from a stack of interferometric SAR images. This work concerns X-band PSI and, in particular, PSI based on very high resolution (VHR StripMap CosmoSkyMed and TerraSAR-X SAR imagery. In fact, it mainly focuses on the technical aspects of deformation measurement and monitoring over urban areas. A key technical aspect analysed in this paper is the thermal expansion component of PSI observations, which is a result of temperature differences in the imaged area between SAR acquisitions. This component of PSI observations is particularly important in the urban environment. This is an interesting feature of PSI, which can be surely used to illustrate the high sensitivity of X-band PSI to very subtle displacements. Thermal expansion can have a strong impact on the PSI products, especially on the deformation velocity maps and deformation time series, if not properly handled during the PSI data processing and analysis, and a comprehensive discussion of this aspect will be provided in this paper. The importance of thermal expansion is related to the fact that the PSI analyses are often performed using limited stacks of images, which may cover a limited time period, e.g. several months only. These two factors (limited number of images and short period make the impact of a non-modelled thermal expansion particularly critical. This issue will be illustrated considering different case studies based on TerraSAR-X and CosmoSkyMed PSI data. Besides, an extended PSI model which alleviates this problem will be described and case studies from the Barcelona metropolitan area will demonstrate the effectiveness of the proposed strategy.

  2. X-band Linac for a 6 MeV dual-head radiation therapy gantry

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Hyun; Shin, Seung-Wook; Lee, Jongchul; Kim, Hui-Su [WCU Department of Energy Science, Suwon 440-746 (Korea, Republic of); Lee, Byeong-No; Lee, Byung-Chul [Radiation Instrumentation Research Division, Korea Atomic Energy Research Institute, Jeongeup 56212 (Korea, Republic of); Park, Hyung-dal; Song, Ki-back [Radiation Technology eXcellence (RTX), Daejeon 305-500 (Korea, Republic of); Song, Ho-seung; Mun, Sangchul; Ha, Donghyup [School of Information and Communication Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Chai, Jong-Seo, E-mail: jschai@skku.edu [School of Information and Communication Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2017-04-21

    We developed a design for a 6 MeV X-band linear accelerator for radiation therapy in a dual-head gantry layout. The dual-head gantry has two linacs that can be operated independently. Each X-band linac accelerates electron bunches using high-power RF and generates X-rays for radiation therapy. It requires a versatile RF system and pulse sequence to accomplish various radiation therapy procedures. The RF system consists of 9.3 GHz, 2 MW X-band magnetron and associated RF transmission components. A test linac was assembled and operated to characterize its RF performance without beam. This paper presents these results along with a description of the gantry linacs and their operational requirements.

  3. Composition-tuned band gap energy and refractive index in GaS{sub x}Se{sub 1−x} layered mixed crystals

    Energy Technology Data Exchange (ETDEWEB)

    Isik, Mehmet, E-mail: mehmet.isik@atilim.edu.tr [Department of Electrical and Electronics Engineering, Atilim University, 06836, Ankara (Turkey); Gasanly, Nizami [Department of Physics, Middle East Technical University, 06800, Ankara (Turkey); Virtual International Scientific Research Centre, Baku State University, 1148, Baku (Azerbaijan)

    2017-04-01

    Transmission and reflection measurements on GaS{sub x}Se{sub 1−x} mixed crystals (0 ≤ x ≤ 1) were carried out in the 400–1000 nm spectral range. Band gap energies of the studied crystals were obtained using the derivative spectra of transmittance and reflectance. The compositional dependence of band gap energy revealed that as sulfur (selenium) composition is increased (decreased) in the mixed crystals, band gap energy increases quadratically from 1.99 eV (GaSe) to 2.55 eV (GaS). Spectral dependencies of refractive indices of the mixed crystals were plotted using the reflectance spectra. It was observed that refractive index decreases nearly in a linear behavior with increasing band gap energy for GaS{sub x}Se{sub 1−x} mixed crystals. Moreover, the composition ratio of the mixed crystals was obtained from the energy dispersive spectroscopy measurements. The atomic compositions of the studied crystals are well-matched with composition x increasing from 0 to 1 by intervals of 0.25. - Highlights: • Transmission and reflection experiments were performed on GaS{sub x}Se{sub 1−x} mixed crystals. • Derivative spectra of transmittance and reflectance were used for analyses. • Compositional dependence of band gap energy and refractive index were reported.

  4. Band-gap measurements of bulk and nanoscale hematite by soft x-ray spectroscopy

    DEFF Research Database (Denmark)

    Gilbert, B.; Frandsen, Cathrine; Maxey, E.R.

    2009-01-01

    Chemical and photochemical processes at semiconductor surfaces are highly influenced by the size of the band gap, and ability to control the band gap by particle size in nanomaterials is part of their promise. The combination of soft x-ray absorption and emission spectroscopies provides band......-gap determination in bulk and nanoscale itinerant electron semiconductors such as CdS and ZnO, but this approach has not been established for materials such as iron oxides that possess band-edge electronic structure dominated by electron correlations. We performed soft x-ray spectroscopy at the oxygen K...

  5. Strongly correlated impurity band superconductivity in diamond: X-ray spectroscopic evidence

    Directory of Open Access Journals (Sweden)

    G. Baskaran

    2006-01-01

    Full Text Available In a recent X-ray absorption study in boron doped diamond, Nakamura et al. have seen a well isolated narrow boron impurity band in non-superconducting samples and an additional narrow band at the chemical potential in a superconducting sample. We interpret the beautiful spectra as evidence for upper Hubbard band of a Mott insulating impurity band and an additional metallic 'mid-gap band' of a conducting 'self-doped' Mott insulator. This supports the basic framework of a recent theory of the present author of strongly correlated impurity band superconductivity (impurity band resonating valence bond, IBRVB theory in a template of a wide-gap insulator, with no direct involvement of valence band states.

  6. X-band RF Photoinjector for Laser Compton X-ray and Gamma-ray Sources

    Energy Technology Data Exchange (ETDEWEB)

    Marsh, R. A. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Anderson, G. G. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Anderson, S. G. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Gibson, D. J. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Barty, C. J. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

    2015-05-06

    Extremely bright narrow bandwidth gamma-ray sources are expanding the application of accelerator technology and light sources in new directions. An X-band test station has been commissioned at LLNL to develop multi-bunch electron beams. This multi-bunch mode will have stringent requirements for the electron bunch properties including low emittance and energy spread, but across multiple bunches. The test station is a unique facility featuring a 200 MV/m 5.59 cell X-band photogun powered by a SLAC XL4 klystron driven by a Scandinova solid-state modulator. This paper focuses on its current status including the generation and initial characterization of first electron beam. Design and installation of the inverse-Compton scattering interaction region and upgrade paths will be discussed along with future applications.

  7. Medical application and its promotion of X-band linacs

    International Nuclear Information System (INIS)

    Uesaka, Mitsuru; Dobashi, Katsuhiro; Kaneyasu, Tatsuo

    2005-01-01

    This article presents the current status of the development of the monochromatic tunable hard X-ray source by the X-band linac and YAG leasers. New medical applications such as 2 colors CT and Drug Delivery System (DDS) are planned. Finally, the virtual laboratory for the distribution of the system to the society is discussed. (author)

  8. Control of Ge1-x-ySixSny layer lattice constant for energy band alignment in Ge1-xSnx/Ge1-x-ySixSny heterostructures

    Science.gov (United States)

    Fukuda, Masahiro; Watanabe, Kazuhiro; Sakashita, Mitsuo; Kurosawa, Masashi; Nakatsuka, Osamu; Zaima, Shigeaki

    2017-10-01

    The energy band alignment of Ge1-xSnx/Ge1-x-ySixSny heterostructures was investigated, and control of the valence band offset at the Ge1-xSnx/Ge1-x-ySixSny heterointerface was achieved by controlling the Si and Sn contents in the Ge1-x-ySixSny layer. The valence band offset in the Ge0.902Sn0.098/Ge0.41Si0.50Sn0.09 heterostructure was evaluated to be as high as 330 meV, and its conduction band offset was estimated to be 150 meV by considering the energy bandgap calculated from the theoretical prediction. In addition, the formation of the strain-relaxed Ge1-x-ySixSny layer was examined and the crystalline structure was characterized. The epitaxial growth of a strain-relaxed Ge0.64Si0.21Sn0.15 layer with the degree of strain relaxation of 55% was examined using a virtual Ge substrate. Moreover, enhancement of the strain relaxation was demonstrated by post-deposition annealing, where a degree of strain relaxation of 70% was achieved after annealing at 400 °C. These results indicate the possibility for enhancing the indirect-direct crossover with a strained and high-Sn-content Ge1-xSnx layer on a strain-relaxed Ge1-x-ySixSny layer, realizing preferable carrier confinement by type-I energy band alignment with high conduction and valence band offsets.

  9. Design of an X-band accelerating structure using a newly developed structural optimization procedure

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xiaoxia [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Fang, Wencheng; Gu, Qiang [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhao, Zhentang, E-mail: zhaozhentang@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

    2017-05-11

    An X-band high gradient accelerating structure is a challenging technology for implementation in advanced electron linear accelerator facilities. The present work discusses the design of an X-band accelerating structure for dedicated application to a compact hard X-ray free electron laser facility at the Shanghai Institute of Applied Physics, and numerous design optimizations are conducted with consideration for radio frequency (RF) breakdown, RF efficiency, short-range wakefields, and dipole/quadrupole field modes, to ensure good beam quality and a high accelerating gradient. The designed X-band accelerating structure is a constant gradient structure with a 4π/5 operating mode and input and output dual-feed couplers in a racetrack shape. The design process employs a newly developed effective optimization procedure for optimization of the X-band accelerating structure. In addition, the specific design of couplers providing high beam quality by eliminating dipole field components and reducing quadrupole field components is discussed in detail.

  10. ESR dating at K and X band of northeastern Brazilian megafauna

    International Nuclear Information System (INIS)

    Kinoshita, Angela; Magnolia Franca, Alcina; Augusto Costa de Almeida, Jose; Maria Figueiredo, Ana; Nicolucci, Patricia; Graeff, Carlos F.O.; Baffa, Oswaldo

    2005-01-01

    The archaeological dose (AD) was measured in three tooth samples of giant mammals that belonged to Brazilian megafauna using electron spin resonance (ESR) spectroscopy at X-band (ν ∼9.5GHz) and K-band (ν ∼24GHz). Samples were collected in Lagoa de Dentro, Puxinana city in Paraiba, a northeast state in Brazil and were identified as Haplomastodon waringi (Holland) (two teeth) and one tooth sample of Xenorhinotherium bahiense (Cartele and Lessa). The average AD led to an age for the Haplomastodon samples of 11.6kybp. For one sample (Haplomastodon) K-band was also employed to evaluate the AD. The K-band spectrum had three components, determined using spectral simulation as follows: a wide isotropic line with g factor 2.0048, an orthorhombic line with gx=2.0034, gy=2.0022 and gz=1.9974, and another isotropic line with g factor 2.0008. The amplitude of these three signals increase with the added dose and the average dose found was 26+/-5Gy. This result is compatible with the AD determined with X-band 21+/-3Gy

  11. Band structure and optical properties of sinusoidal superlattices: ZnSe1-xTex

    International Nuclear Information System (INIS)

    Yang, G.; Lee, S.; Furdyna, J. K.

    2000-01-01

    This paper examines the band structure and optical selection rules in superlattices with a sinusoidal potential profile. The analysis is motivated by the recent successful fabrication of high quality ZnSe 1-x Te x superlattices in which the composition x varies sinusoidally along the growth direction. Although the band alignment in the ZnSe 1-x Te x sinusoidal superlattices is staggered (type II), they exhibit unexpectedly strong photoluminescence, thus suggesting interesting optical behavior. The band structure of such sinusoidal superlattices is formulated in terms of the nearly-free-electron (NFE) approximation, in which the superlattice potential is treated as a perturbation. The resulting band structure is unique, characterized by a single minigap separating two wide, free-electron-like subbands for both electrons and holes. Interband selection rules are derived for optical transitions involving conduction and valence-band states at the superlattice Brillouin-zone center, and at the zone edge. A number of transitions are predicted due to wave-function mixing of different subband states. It should be noted that the zone-center and zone-edge transitions are especially easy to distinguish in these superlattices because of the large width of the respective subbands. The results of the NFE approximation are shown to hold surprisingly well over a wide range of parameters, particularly when the period of the superlattice is short. (c) 2000 The American Physical Society

  12. C/X-band SAR interferometry applied to ground monitoring: examples and new potential

    Science.gov (United States)

    Nutricato, Raffaele; Nitti, Davide O.; Bovenga, Fabio; Refice, Alberto; Wasowski, Janusz; Chiaradia, Maria T.

    2013-10-01

    Classical applications of the MTInSAR techniques have been carried out in the past on medium resolution data acquired by the ERS, Envisat (ENV) and Radarsat sensors. The new generation of high-resolution X-Band SAR sensors, such as TerraSAR-X (TSX) and the COSMO-SkyMed (CSK) constellation allows acquiring data with spatial resolution reaching metric/submetric values. Thanks to the finer spatial resolution with respect to C-band data, X-band InSAR applications result very promising for monitoring single man-made structures (buildings, bridges, railways and highways), as well as landslides. This is particularly relevant where C-band data show low density of coherent scatterers. Moreover, thanks again to the higher resolution, it is possible to infer reliable estimates of the displacement rates with a number of SAR scenes significantly lower than in C-band within the same time span or by using more images acquired in a narrower time span. We present examples of the application of a Persistent Scatterers Interferometry technique, namely the SPINUA algorithm, to data acquired by ENV, TSX and CSK on selected number of sites. Different cases are considered concerning monitoring of both instable slopes and infrastructure. Results are compared and commented with particular attention paid to the advantages provided by the new generation of X-band high resolution space-borne SAR sensors.

  13. Band alignment of two-dimensional metal monochalcogenides MXs (M=Ga,In; X=S,Se,Te

    Directory of Open Access Journals (Sweden)

    Huazheng Sun

    2017-09-01

    Full Text Available Monolayer metal monochalcogenides MXs (M=Ga,In; X=S,Se,Te form a new class of two-dimensional semiconductors with indirect band gaps, and their band alignment information is investigated via first principles calculations. The dependence of band gap, valence-band maximum, conduction band minimum, and charge transfer on the M or X element has been obtained and can be understood from the orbital analysis of the band edges. Potential applications of metal monochalcogenides to design van der Waals heterostructures and catalyse the photo-splitting reaction of water have been discussed.

  14. Group-velocity matched nonlinear photonic crystal fibers

    DEFF Research Database (Denmark)

    Bache, Morten; Lægsgaard, Jesper; Bang, Ole

    2006-01-01

    A quadratic nonlinear index-guiding silica PCF is optimized for efficient second-harmonic generation through dispersion calculations. Zero group-velocity mismatch is possible for any pump wavelength above 780 nm. Very high conversion efficiencies and bandwidths are found....

  15. Playback system designed for X-Band SAR

    International Nuclear Information System (INIS)

    Yuquan, Liu; Changyong, Dou

    2014-01-01

    SAR(Synthetic Aperture Radar) has extensive application because it is daylight and weather independent. In particular, X-Band SAR strip map, designed by Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, provides high ground resolution images, at the same time it has a large spatial coverage and a short acquisition time, so it is promising in multi-applications. When sudden disaster comes, the emergency situation acquires radar signal data and image as soon as possible, in order to take action to reduce loss and save lives in the first time. This paper summarizes a type of X-Band SAR playback processing system designed for disaster response and scientific needs. It describes SAR data workflow includes the payload data transmission and reception process. Playback processing system completes signal analysis on the original data, providing SAR level 0 products and quick image. Gigabit network promises radar signal transmission efficiency from recorder to calculation unit. Multi-thread parallel computing and ping pong operation can ensure computation speed. Through gigabit network, multi-thread parallel computing and ping pong operation, high speed data transmission and processing meet the SAR radar data playback real time requirement

  16. Playback system designed for X-Band SAR

    Science.gov (United States)

    Yuquan, Liu; Changyong, Dou

    2014-03-01

    SAR(Synthetic Aperture Radar) has extensive application because it is daylight and weather independent. In particular, X-Band SAR strip map, designed by Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, provides high ground resolution images, at the same time it has a large spatial coverage and a short acquisition time, so it is promising in multi-applications. When sudden disaster comes, the emergency situation acquires radar signal data and image as soon as possible, in order to take action to reduce loss and save lives in the first time. This paper summarizes a type of X-Band SAR playback processing system designed for disaster response and scientific needs. It describes SAR data workflow includes the payload data transmission and reception process. Playback processing system completes signal analysis on the original data, providing SAR level 0 products and quick image. Gigabit network promises radar signal transmission efficiency from recorder to calculation unit. Multi-thread parallel computing and ping pong operation can ensure computation speed. Through gigabit network, multi-thread parallel computing and ping pong operation, high speed data transmission and processing meet the SAR radar data playback real time requirement.

  17. Spatially-protected Topology and Group Cohomology in Band Insulators

    Science.gov (United States)

    Alexandradinata, A.

    This thesis investigates band topologies which rely fundamentally on spatial symmetries. A basic geometric property that distinguishes spatial symmetry regards their transformation of the spatial origin. Point groups consist of spatial transformations that preserve the spatial origin, while un-split extensions of the point groups by spatial translations are referred to as nonsymmorphic space groups. The first part of the thesis addresses topological phases with discretely-robust surface properties: we introduce theories for the Cnv point groups, as well as certain nonsymmorphic groups that involve glide reflections. These band insulators admit a powerful characterization through the geometry of quasimomentum space; parallel transport in this space is represented by the Wilson loop. The non-symmorphic topology we study is naturally described by a further extension of the nonsymmorphic space group by quasimomentum translations (the Wilson loop), thus placing real and quasimomentum space on equal footing -- here, we introduce the language of group cohomology into the theory of band insulators. The second part of the thesis addresses topological phases without surface properties -- their only known physical consequences are discrete signatures in parallel transport. We provide two such case studies with spatial-inversion and discrete-rotational symmetries respectively. One lesson learned here regards the choice of parameter loops in which we carry out transport -- the loop must be chosen to exploit the symmetry that protects the topology. While straight loops are popular for their connection with the geometric theory of polarization, we show that bent loops also have utility in topological band theory.

  18. Band offset in zinc oxy-sulfide/cubic-tin sulfide interface from X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sanal, K.C.; Nair, P.K.; Nair, M.T.S., E-mail: mtsn@ier.unam.mx

    2017-02-28

    Highlights: • Zinc oxy-sulfide thin films, 175–240 nm, deposited by rf-sputtering from targets of ZnO + ZnS. • Oxygen content in thin films is enhanced 3–4 times compared with that in ZnO:ZnS targets. • Thin film ZnO{sub x}S{sub 1−x} with x = 0.88–0.27 and optical band gap 2.8–3.2 eV is suitable for solar cells. • The conduction band offset with SnS of cubic structure studied by XPS are +0.41 to −0.28 eV. - Abstract: Zinc oxy-sulfide, ZnO{sub x}S{sub 1−x}, has been found to provide better band alignment in thin film solar cells of tin sulfide of orthorhombic crystalline structure. Here we examine ZnO{sub x}S{sub 1−x}/SnS-CUB interface, in which the ZnO{sub x}S{sub 1−x} thin film was deposited by radio frequency (rf) magnetron sputtering on SnS thin film of cubic (CUB) crystalline structure with a band gap (E{sub g}) of 1.72 eV, obtained via chemical deposition. X-ray photoelectron spectroscopy provides the valence band maxima of the materials and hence places the conduction band offset of 0.41 eV for SnS-CUB/ZnO{sub 0.27}S{sub 0.73} and −0.28 eV for SnS-CUB/ZnO{sub 0.88}S{sub 0.12} interfaces. Thin films of ZnO{sub x}S{sub 1−x} with 175–240 nm in thickness were deposited from targets prepared with different ZnO to ZnS molar ratios. With the target of molar ratio of 1:13.4, the thin films are of composition ZnO{sub 0.27}S{sub 0.73} with hexagonal crystalline structure and with that of 1:1.7 ratio, it is ZnO{sub 0.88}S{sub 0.12}. The optical band gap of the ZnO{sub x}S{sub 1−x} thin films varies from 2.90 eV to 3.21 eV as the sulfur to zinc ratio in the film increases from 0.12:1 to 0.73:1 as determined from X-ray diffraction patterns. Thus, band offsets sought for absorber materials and zinc oxy-sulfide in solar cells may be achieved through a choice of ZnO:ZnS ratio in the sputtering target.

  19. Evaluation of dual polarization scattering matrix radar rain backscatter measurements in the X- and Q-bands

    Science.gov (United States)

    Agrawal, A. P.; Carnegie, D. W.; Boerner, W.-M.

    This paper presents an evaluation of polarimetric rain backscatter measurements collected with coherent dual polarization radar systems in the X (8.9 GHz) and Q (45GHz) bands, the first being operated in a pulsed mode and the second being a FM-CW system. The polarimetric measurement data consisted for each band of fifty files of time-sequential scattering matrix measurements expressed in terms of a linear (H, V) antenna polarization state basis. The rain backscattering takes place in a rain cell defined by the beam widths and down range distances of 275 ft through 325 ft and the scattering matrices were measured far below the hydrometeoric scattering center decorrelation time so that ensemble averaging of time-sequential scattering matrices may be applied. In the data evaluation great care was taken in determining: (1) polarimetric Doppler velocities associated with the motion of descending oscillating raindrops and/or eddies within the moving swaths of coastal rain showers, and (2) also the properties of the associated co/cross-polarization rain clutter nulls and their distributions on the Poincare polarization sphere.

  20. Crustal structure beneath discovery bank in the South Scotia Sea from group velocity tomography and seismic reflection data

    International Nuclear Information System (INIS)

    Vuan, A.; Lodolo, E.; Panza, G.F.

    2003-09-01

    Bruce, Discovery, Herdman and Jane Banks, all located along the central-eastern part of the South Scotia Ridge (i.e., the Antarctica-Scotia plate boundary), represent isolated topographic reliefs surrounded by relatively young oceanic crust, whose petrological and structural nature is still the subject of speculations due to the lack of resolving data. In the Scotia Sea and surrounding regions negative anomalies of about 34% are reported in large-scale group velocity tomography maps. The spatial resolution (∼500 km) of these maps does not warrant any reliable interpretation of such anomalies. A recent surface wave tomography in the same area, performed using broad band seismic stations and 300 regional events, shows that in the period range from 15 s to 50 s the central-eastern part of the South Scotia Ridge is characterized by negative anomalies of the group velocities as large as 6. The resolution of our data set (∼300 km) makes it possible to distinguish an area (centered at 61 deg S and 36 deg W) with a crust thicker than 25 km, and a shear wave velocity vs. depth profile similar to that found beneath the northern tip of the Antarctic Peninsula and southern South America. Rayleigh and Love wave dispersion curves are inverted in the period range from 15 s to 80 s to obtain shear wave velocity profiles that suggest a continental nature of Discovery Bank. The continental-type crust of this topographic relief is in agreement with the interpretation of a multi-channel seismic reflection profile acquired across this rise. Peculiar acoustic facies are observed in this profile and are interpreted as thinned and faulted continental plateau. The boundaries of the negative group velocity anomalies are marked by a high seismicity rate. Historical normal faulting earthquakes with magnitude around 7 are localised between the low velocity anomaly region in the eastern South Scotia Ridge and the high velocity anomaly region associated with the surrounding oceanic crust

  1. Scaling laws for the rotational velocity of a J x B driven rotating plasma

    International Nuclear Information System (INIS)

    Igarashi, Yasuhito; Kataoka, Tomohiro; Ikehata, Takashi; Sato, Naoyuki; Tanabe, Toshio; Mase, Hiroshi

    1994-01-01

    Rapidly rotating plasmas of helium and argon have been extracted from a coaxial plasma gun operated in pulsed glow mode. The rotational velocity and its parametric dependence have been analyzed systematically by means of visible - emission spectroscopy. The plasma is observed to rotate rigidly inside the diameter of the gun anode while outside the velocity decreases rapidly ; furthermore, different ions are found to rotate at different angular frequencies as ω (Ar + ) = 0.5 x 10 6 rad/sec, ω (Ar 2+ ) = 1.1 x 10 6 rad/sec, ω (C 2+ ) = 1.8 x 10 6 rad/sec, ω (N + ) = 1.2 x 10 6 rad/sec. The plasma density and rotational velocity have been measured as a function of the discharge current and magnetic field to derive experimental scaling laws. They are summarized as : 1. Ion density is proportional to the square of discharge current. 2. Rotational and axial velocities are proportional to the driving force per ion. These results are confirmed to agree well with a theoretical prediction. (author)

  2. Forbidden energy band gap in diluted a-Ge{sub 1-x}Si{sub x}:N films

    Energy Technology Data Exchange (ETDEWEB)

    Guarneros, C.; Rebollo-Plata, B. [Posgrado en Fisica Aplicada, Facultad de Ciencias Fisico-Matematicas, Benemerita Universidad Autonoma de Puebla, Blvd. 14 Sur 6301, Col. San Manuel, 72570, Puebla (Mexico); Lozada-Morales, R., E-mail: rlozada@fcfm.buap.mx [Posgrado en Fisica Aplicada, Facultad de Ciencias Fisico-Matematicas, Benemerita Universidad Autonoma de Puebla, Blvd. 14 Sur 6301, Col. San Manuel, 72570, Puebla (Mexico); Espinosa-Rosales, J.E. [Posgrado en Fisica Aplicada, Facultad de Ciencias Fisico-Matematicas, Benemerita Universidad Autonoma de Puebla, Blvd. 14 Sur 6301, Col. San Manuel, 72570, Puebla (Mexico); Portillo-Moreno, J. [Facultad de Ciencias Quimicas, Benemerita Universidad Autonoma de Puebla, Blvd. 14 Sur 6301, Col. San Manuel, 72570, Puebla (Mexico); Zelaya-Angel, O. [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados del IPN, PO Box 14-740, Mexico 07360 D.F. (Mexico)

    2012-06-01

    By means of electron gun evaporation Ge{sub 1-x}Si{sub x}:N thin films, in the entire range 0 {<=} x {<=} 1, were prepared on Si (100) and glass substrates. The initial vacuum reached was 6.6 Multiplication-Sign 10{sup -4} Pa, then a pressure of 2.7 Multiplication-Sign 10{sup -2} Pa of high purity N{sub 2} was introduced into the chamber. The deposition time was 4 min. Crucible-substrate distance was 18 cm. X-ray diffraction patterns indicate that all the films were amorphous (a-Ge{sub 1-x}Si{sub x}:N). The nitrogen concentration was of the order of 1 at% for all the films. From optical absorption spectra data and by using the Tauc method the energy band gap (E{sub g}) was calculated. The Raman spectra only reveal the presence of Si-Si, Ge-Ge, and Si-Ge bonds. Nevertheless, infrared spectra demonstrate the existence of Si-N and Ge-N bonds. The forbidden energy band gap (E{sub g}) as a function of x in the entire range 0 {<=} x {<=} 1 shows two well defined regions: 0 {<=} x {<=} 0.67 and 0.67 {<=} x {<=} 1, due to two different behaviors of the band gap, where for x > 0.67 exists an abruptly change of E{sub g}(x). In this case E{sub g}(x) versus x is different to the variation of E{sub g} in a-Ge{sub 1-x}Si{sub x} and a-Ge{sub 1-x}Si{sub x}:H. This fact can be related to the formation of Ge{sub 3}N{sub 4} and GeSi{sub 2}N{sub 4} when x {<=} 0.67, and to the formation of Si{sub 3}N{sub 4} and GeSi{sub 2}N{sub 4} for 0.67 {<=} x. - Highlights: Black-Right-Pointing-Pointer Nitrogen doped amorphous Ge{sub 1-x}Si{sub x} thin films are grown by electron gun technique. Black-Right-Pointing-Pointer Nitrogen atoms on E{sub g} of the a-Ge{sub 1-x}Si{sub x} films in the 0 Pound-Sign x Pound-Sign 1 range are analyzed. Black-Right-Pointing-Pointer Variation in 0 Pound-Sign x Pound-Sign 1 range shows a warped change of E{sub g} in 1.0 - 3.6 eV range. Black-Right-Pointing-Pointer The change in E{sub g}(x) behavior when x {approx} 0.67 was associated with Ge{sub 2}SiN{sub 4

  3. Development of Method for X-band Weather Radar Calibration

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ellerbæk; Thorndahl, Søren Liedtke; Rasmussen, Michael R.

    2013-01-01

    Calibration of the X-band LAWR (Local Area Weather Radar) is traditionally based on an assumed linear relation between the LAWRradar output and the rainfall intensity. However, closer inspections of the data reveal that the validity of this linear assumption is doubtful. Previous studies of this ......Calibration of the X-band LAWR (Local Area Weather Radar) is traditionally based on an assumed linear relation between the LAWRradar output and the rainfall intensity. However, closer inspections of the data reveal that the validity of this linear assumption is doubtful. Previous studies...... of this type of weather radar have also illustrated that the radar commonly has difficulties in estimating high rain rates. Therefore, a new radar–rainfall transformation model and a calibration method have been developed. The new method is based on nonlinear assumptions and is aimed at describing the whole...

  4. Bulk and surface band structure of the new family of semiconductors BiTeX (X=I, Br, Cl)

    International Nuclear Information System (INIS)

    Moreschini, L.; Autès, G.; Crepaldi, A.; Moser, S.; Johannsen, J.C.; Kim, K.S.; Berger, H.; Bugnon, Ph.; Magrez, A.; Denlinger, J.; Rotenberg, E.; Bostwick, A.; Yazyev, O.V.

    2015-01-01

    Highlights: • We provide an ARPES comparison between the three tellurohalides BiTeX (X = I, Br, Cl). • They present a similar band structure with namely spin-split bulk and surface states. • They offer, except for BiTeCl, the possibility of ambipolar conduction. • They can be easily doped. • From the data appeared so far, BiTeBr may be the most appealing for applications. - Abstract: We present an overview of the new family of semiconductors BiTeX (X = I, Br, Cl) from the perspective of angle resolved photoemission spectroscopy. The strong band bending occurring at the surface potentially endows them with a large flexibility, as they are capable of hosting both hole and electron conduction, and can be modified by inclusion or adsorption of foreign atoms. In addition, their trigonal crystal structure lacks a center of symmetry and allows for both bulk and surface spin-split bands at the Fermi level. We elucidate analogies and differences among the three materials, also in the light of recent theoretical and experimental work

  5. THE A-X INFRARED BANDS OF ALUMINUM OXIDE IN STARS: SEARCH AND NEW DETECTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, D. P. K.; Mathew, Blesson; Ashok, N. M. [Astronomy and Astrophysics Division, Physical Research Laboratory, Navrangpura, Ahmedabad, Gujarat 380009 (India); Varricatt, W. P. [Joint Astronomy Centre, 660 N. Aohoku Place, University Park, Hilo, Hawaii, HI 96720 (United States); Launila, O., E-mail: orion@prl.res.in [KTH-AlbaNova, Applied Physics, Roslagstullsbacken 21, 106 91 Stockholm (Sweden)

    2012-07-01

    We describe a search for the A-X infrared bands of AlO with a view toward better understanding the characteristics of this radical. These bands are infrequently encountered in astronomical sources but surprisingly were very prominent in the spectra of two well-known, novalike variables (V838 Mon and V4332 Sgr) thereby motivating us to explore the physical conditions necessary for their excitation. In this study, we present the detection of A-X bands in the spectra of 13 out of 17 stars, selected on the basis of their J - K colors as potential candidates for detection of these bands. The majority of the AlO detections are in asymptotic giant branch (AGB) stars, viz., nine OH/IR stars, two Mira variables, and two bright infrared sources. Our study shows that the A-X bands are fairly prevalent in sources with low temperature and O-rich environments. Interesting variation in the strength of the AlO bands in one of the sources (IRAS 18530+0817) is reported and the cause for this is examined. Possible applications of the present study are discussed in terms of the role of AlO in alumina dust formation, the scope for estimating the radioactive {sup 26}Al content in AGB stars from the A-X bands, and providing possible targets for further mm/radio studies of AlO which has recently been discovered at millimeter wavelengths.

  6. Band gap calculations of the semiconductor BNxP1−x using modified Becke–Johnson approximation

    International Nuclear Information System (INIS)

    Benkraouda, M.; Amrane, N.

    2013-01-01

    Highlights: ► The Modified Becke–Johnson scheme gives a very accurate band gap. ► We have shown the invalidity of Vegard’s linear rule for BN x P 1−x . ► The band gap changes with alloy concentration are important in band gap engineering. - Abstract: In this work, the electronic properties of BN, BP and BN x P 1−x compounds have been investigated by means of first-principles density-functional total-energy calculation using the all-electron full potential linear augmented plane-wave method (FP-LAPW). The (FP-LAPW) method was used within the density functional theory (DFT) along with the Engel–Vosko and Becke–Johnson exchange correlation potential. The energy bands along high symmetry directions, the density of states and bowing distributions are calculated. The results have been discussed in terms of previously existing experimental and theoretical data, and comparisons with similar compounds have been made. Analysis of band structure suggests direct and pseudo-direct band gaps for both compounds.

  7. Sleuthing the MSL EDL performance from an X band carrier perspective

    Science.gov (United States)

    Oudrhiri, Kamal; Asmar, Sami; Estabrook, Polly; Kahan, Daniel; Mukai, Ryan; Ilott, Peter; Schratz, Brian; Soriano, Melissa; Finley, Susan; Shidner, Jeremy

    During the Entry, Descent, and Landing (EDL) of NASA's Mars Science Laboratory (MSL), or Curiosity, rover to Gale Crater on Mars on August 6, 2012 UTC, the rover transmitted an X-band signal composed of carrier and tone frequencies and a UHF signal modulated with an 8kbps data stream. During EDL, the spacecraft's orientation is determined by its guidance and mechanical subsystems to ensure that the vehicle land safely at its destination. Although orientation to maximize telecom performance is not possible, antennas are especially designed and mounted to provide the best possible line of sight to Earth and to the Mars orbiters supporting MSL's landing. The tones and data transmitted over these links are selected carefully to reflect the most essential parameters of the vehicle's state and the performance of the EDL subsystems for post-EDL reconstruction should no further data transmission from the vehicle be possible. This paper addresses the configuration of the X band receive system used at NASA / JPL's Deep Space Network (DSN) to capture the signal spectrum of MSL's X band carrier and tone signal, examines the MSL vehicle state information obtained from the X band carrier signal only and contrasts the Doppler-derived information against the post-EDL known vehicle state. The paper begins with a description of the MSL EDL sequence of events and discusses the impact of the EDL maneuvers such as guided entry, parachute deploy, and powered descent on the frequency observables expected at the DSN. The range of Doppler dynamics possible is derived from extensive 6 Degrees-Of-Freedom (6 DOF) vehicle state calculations performed by MSL's EDL simulation team. The configuration of the DSN's receive system, using the Radio Science Receivers (RSR) to perform open-loop recording for both for nominal and off-nominal EDL scenarios, is detailed. Expected signal carrier power-to-noise levels during EDL are shown and their impact on signal detection is considered. Particula

  8. EXPLORING THE DIVERSITY OF GROUPS AT 0.1 < z < 0.8 WITH X-RAY AND OPTICALLY SELECTED SAMPLES

    Energy Technology Data Exchange (ETDEWEB)

    Connelly, J. L. [Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany); Wilman, David J.; Finoguenov, Alexis; Saglia, Roberto [Max Planck Institute for Extraterrestrial Physics, P.O. Box 1312, Giessenbachstr., D-85741 Garching (Germany); Hou, Annie; Parker, Laura C.; Henderson, Robert D. E. [Department of Physics and Astronomy, McMaster University, Hamilton ON L8S4M1 (Canada); Mulchaey, John S. [Observatories of the Carnegie Institution, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); McGee, Sean L.; Balogh, Michael L. [Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Bower, Richard G. [Department of Physics, University of Durham, Durham DH1 3LE (United Kingdom)

    2012-09-10

    We present the global group properties of two samples of galaxy groups containing 39 high-quality X-ray-selected systems and 38 optically (spectroscopically) selected systems in coincident spatial regions at 0.12 < z < 0.79. The total mass range of the combined sample is {approx}(10{sup 12}-5) Multiplication-Sign 10{sup 14} M{sub Sun }. Only nine optical systems are associable with X-ray systems. We discuss the confusion inherent in the matching of both galaxies to extended X-ray emission and of X-ray emission to already identified optical systems. Extensive spectroscopy has been obtained and the resultant redshift catalog and group membership are provided here. X-ray, dynamical, and total stellar masses of the groups are also derived and presented. We explore the effects of utilizing different centers and applying three different kinds of radial cut to our systems: a constant cut of 1 Mpc and two r{sub 200} cuts, one based on the velocity dispersion of the system and the other on the X-ray emission. We find that an X-ray-based r{sub 200} results in less scatter in scaling relations and less dynamical complexity as evidenced by results of the Anderson-Darling and Dressler-Schectman tests, indicating that this radius tends to isolate the virialized part of the system. The constant and velocity dispersion based cuts can overestimate membership and can work to inflate velocity dispersion and dynamical and stellar mass. We find L{sub X} -{sigma} and M{sub stellar}-L{sub X} scaling relations for X-ray and optically selected systems are not dissimilar. The mean fraction of mass found in stars, excluding intracluster light, for our systems is {approx}0.014 with a logarithmic standard deviation of 0.398 dex. We also define and investigate a sample of groups which are X-ray underluminous given the total group stellar mass. For these systems the fraction of stellar mass contributed by the most massive galaxy is typically lower than that found for the total population of

  9. Integrated X-band FMCW front-end in SiGe BiCMOS

    NARCIS (Netherlands)

    Suijker, Erwin; de Boer, Lex; Visser, Guido; van Dijk, Raymond; Poschmann, Michael; van Vliet, Frank Edward

    2010-01-01

    An integrated X-band FMCW front-end is reported. The front-end unites the core functionality of an FMCW transmitter and receiver in a 0.25 μm SiGe BiCMOS process. The chip integrates a PLL for the carrier generation, and single-side band and image-reject mixers for up- and down-conversion of the

  10. THE REFINED SHOCK VELOCITY OF THE X-RAY FILAMENTS IN THE RCW 86 NORTHEAST RIM

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Hiroya; Castro, Daniel; Williams, Brian J.; Petre, Robert [NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States); Katsuda, Satoru [Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Lopez, Laura A. [Department of Astronomy and Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, OH 43210 (United States); Slane, Patrick O.; Smith, Randall K., E-mail: hiroya.yamaguchi@nasa.gov [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2016-03-20

    A precise measurement of shock velocities is crucial for constraining the mechanism and efficiency of cosmic-ray (CR) acceleration at supernova remnant (SNR) shock fronts. The northeastern rim of the SNR RCW 86 is thought to be a particularly efficient CR acceleration site, owing to the recent result in which an extremely high shock velocity of ∼6000 km s{sup −1} was claimed. Here, we revisit the same SNR rim with the Chandra X-ray Observatory, 11 years after the first observation. This longer baseline than previously available allows us to determine a more accurate proper motion of the nonthermal X-ray filament, revealing a much lower velocity of 3000 ± 340 km s{sup −1} (and even slower at a brighter region). Although the value has dropped to one-half of that from the previous X-ray measurement, it is still higher than the mean velocity of the Hα filaments in this region (∼1200 km s{sup −1}). This discrepancy implies that the filaments bright in nonthermal X-rays and Hα emission trace different velocity components, and thus a CR pressure constrained by combining the X-ray kinematics and the Hα spectroscopy can easily be overestimated. We also measure the proper motion of the thermal X-ray filament immediately to the south of the nonthermal one. The inferred velocity (720 ± 360 km s{sup −1}) is significantly lower than that of the nonthermal filament, suggesting the presence of denser ambient material, possibly a wall formed by a wind from the progenitor, which has drastically slowed down the shock.

  11. Real group velocity in a medium with dissipation

    International Nuclear Information System (INIS)

    Muschietti, L.; Dum, C.T.

    1993-01-01

    When a medium is dissipative, the classic expression for the group velocity, dω/dk, is complex with an imaginary part often being far from negligible. To clarify the role of this imaginary term, the motion of a wave packet in a dissipative, homogeneous medium is examined. The integral representation of the packet is analyzed by means of a saddle-point method. It is shown that in a moving frame attached to its maximum the packet looks self-similar. A Gaussian packet keeps its Gaussian identity, as is familiar for the case of a nondissipative medium. However, the central wave number of the packet slowly changes because of a differential damping among the Fourier components: Im(dω/dk)=dγ/dk≠0, where ω≡ω r +iγ. The packet height can be computed self-consistently as integrated damping (or growth). The real group velocity becomes a time-dependent combination of Re(dω/dk) and Im(dω/dk). Only where the medium is both homogeneous and loss free, does the group velocity remain constant. Simple ''ray-tracing equations'' are derived to follow the packet centers in coordinate and Fourier spaces. The analysis is illustrated with a comparison to geometric optics, and by two applications: the case of a medium with some resonant damping (or growth) and the propagation of whistler waves in a collisional plasma

  12. The Fermi surface and band folding in La{sub 2-x}Sr{sub x}CuO{sub 4}, probed by angle-resolved photoemission

    Energy Technology Data Exchange (ETDEWEB)

    Razzoli, E; Radovic, M; Patthey, L; Shi, M [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Sassa, Y; Chang, J [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Drachuck, G; Keren, A; Shay, M [Department of Physics, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Maansson, M; Mesot, J [Laboratory for Synchrotron and Neutron Spectroscopy, EPF Lausanne, CH-1015 Lausanne (Switzerland); Berntsen, M H; Tjernberg, O [Materials Physics, KTH Royal Institute of Technology, S-16440 Kista (Sweden); Pailhes, S [CEA, CNRS, CE Saclay, Laboratoire Leon Brillouin, F-91191 Gif Sur Yvette (France); Momono, N [Department of Applied Sciences, Muroran Institute of Technology, Muroran 050-8585 (Japan); Oda, M; Ido, M [Department of Physics, Hokkaido University, Sapporo 060-0810 (Japan); Lipscombe, O J; Hayden, S M, E-mail: ming.shi@psi.c [H H Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom)

    2010-12-15

    A systematic angle-resolved photoemission study of the electronic structure of La{sub 2-x}Sr{sub x}CuO{sub 4} in a wide doping range is presented in this paper. In addition to the main energy band, we observed a weaker additional band, the ({pi}, {pi}) folded band, which shows unusual doping dependence. The appearance of the folded band suggests that a Fermi surface reconstruction is doping dependent and could already occur at zero magnetic field.

  13. Helioseismic measurements in the solar envelope using group velocities of surface waves

    Science.gov (United States)

    Vorontsov, S. V.; Baturin, V. A.; Ayukov, S. V.; Gryaznov, V. K.

    2014-07-01

    At intermediate- and high-degree l, solar p and f modes can be considered as surface waves. Using variational principle, we derive an integral expression for the group velocities of the surface waves in terms of adiabatic eigenfunctions of normal modes, and address the benefits of using group-velocity measurements as a supplementary diagnostic tool in solar seismology. The principal advantage of using group velocities, when compared with direct analysis of the oscillation frequencies, comes from their smaller sensitivity to the uncertainties in the near-photospheric layers. We address some numerical examples where group velocities are used to reveal inconsistencies between the solar models and the seismic data. Further, we implement the group-velocity measurements to the calibration of the specific entropy, helium abundance Y, and heavy-element abundance Z in the adiabatically stratified part of the solar convective envelope, using different recent versions of the equation of state. The results are in close agreement with our earlier measurements based on more sophisticated analysis of the solar oscillation frequencies. These results bring further support to the downward revision of the solar heavy-element abundances in recent spectroscopic measurements.

  14. A Coherent Compton Backscattering High Gain FEL using an X-Band Microwave Undulator

    CERN Document Server

    Pellegrini, C; Travish, G

    2005-01-01

    We describe a proposed high-gain FEL using an X-band microwave undulator and operating at a wavelength of about 0.5 μm. The FEL electron beam energy is 65 MeV. The beam is produced by the NLCTA X-band linac at SLAC, using an S-band high-brightness photoinjector. The undulator consists of a circular waveguide with an rf wave counter-propagating with respect to the electron beam. The undulator is powered with two high-power X-band klystrons and a dual-moded pulse compressor recently developed at SLAC. This system is capable of delivering flat-top rf pulses of up to 400 ns and a few hundred megawatts. The equivalent undulator period is 1.4 cm, the radius of the circular pipe is 1 cm, and the undulator parameter is about 0.4 for a helical undulator configuration, obtained using two cross-polarized TE modes, or larger for a planar configuration, using one rf polarization. The undulator is about four meters long. The FEL will reach saturation within this distance when operated in a SASE mode. We describe t...

  15. Band alignment at the Cu{sub 2}ZnSn(S{sub x}Se{sub 1-x}){sub 4}/CdS interface

    Energy Technology Data Exchange (ETDEWEB)

    Haight, Richard; Barkhouse, Aaron; Gunawan, Oki; Shin, Byungha; Copel, Matt; Hopstaken, Marinus; Mitzi, David B [IBM TJ Watson Research Center, P.O. Box 218, Yorktown Hts., New York 10598 (United States)

    2011-06-20

    Energy band alignments between CdS and Cu{sub 2}ZnSn(S{sub x}Se{sub 1-x}){sub 4} (CZTSSe) grown via solution-based and vacuum-based deposition routes were studied as a function of the [S]/[S+Se] ratio with femtosecond laser ultraviolet photoelectron spectroscopy, photoluminescence, medium energy ion scattering, and secondary ion mass spectrometry. Band bending in the underlying CZTSSe layer was measured via pump/probe photovoltage shifts of the photoelectron spectra and offsets were determined with photoemission under flat band conditions. Increasing the S content of the CZTSSe films produces a valence edge shift to higher binding energy and increases the CZTSSe band gap. In all cases, the CdS conduction band offsets were spikes.

  16. Density functional theory calculations for the band gap and formation energy of Pr4-xCaxSi12O3+xN18-x; a highly disordered compound with low symmetry and a large cell size.

    Science.gov (United States)

    Hong, Sung Un; Singh, Satendra Pal; Pyo, Myoungho; Park, Woon Bae; Sohn, Kee-Sun

    2017-06-28

    A novel oxynitride compound, Pr 4-x Ca x Si 12 O 3+x N 18-x , synthesized using a solid-state route has been characterized as a monoclinic structure in the C2 space group using Rietveld refinement on synchrotron powder X-ray diffraction data. The crystal structure of this compound was disordered due to the random distribution of Ca/Pr and N/O ions at various Wyckoff sites. A pragmatic approach for an ab initio calculation based on density function theory (DFT) for this disordered compound has been implemented to calculate an acceptable value of the band gap and formation energy. In general, for the DFT calculation of a disordered compound, a sufficiently large super cell and infinite variety of ensemble configurations is adopted to simulate the random distribution of ions; however, such an approach is time consuming and cost ineffective. Even a single unit cell model gave rise to 43 008 independent configurations as an input model for the DFT calculations. Since it was nearly impossible to calculate the formation energy and the band gap energy for all 43 008 configurations, an elitist non-dominated sorting genetic algorithm (NSGA-II) was employed to find the plausible configurations. In the NSGA-II, all 43 008 configurations were mathematically treated as genomes and the calculated band gap and the formation energy as the objective (fitness) function. Generalized gradient approximation (GGA) was first employed in the preliminary screening using NSGA-II, and thereafter a hybrid functional calculation (HSE06) was executed only for the most plausible GGA-relaxed configurations with lower formation and higher band gap energies. The final band gap energy (3.62 eV) obtained after averaging over the selected configurations, resembles closely the experimental band gap value (4.11 eV).

  17. Group velocity measurement using spectral interference in near-field scanning optical microscopy

    International Nuclear Information System (INIS)

    Mills, John D.; Chaipiboonwong, Tipsuda; Brocklesby, William S.; Charlton, Martin D. B.; Netti, Caterina; Zoorob, Majd E.; Baumberg, Jeremy J.

    2006-01-01

    Near-field scanning optical microscopy provides a tool for studying the behavior of optical fields inside waveguides. In this experiment the authors measure directly the variation of group velocity between different modes of a planar slab waveguide as the modes propagate along the guide. The measurement is made using the spectral interference between pulses propagating inside the waveguide with different group velocities, collected using a near-field scanning optical microscope at different points down the guide and spectrally resolved. The results are compared to models of group velocities in simple guides

  18. Structural and magnetic studies of the Co{sub 1+x}Ti{sub x}Fe{sub 2(1−x)}O{sub 4} ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Amer, M.A., E-mail: moazamer@hotmail.com

    2017-03-15

    The cubic spinel Co{sub 1+x}Ti{sub x}Fe{sub 2(1−x)}O{sub 4} ferrites, 0.0≤x≤0.5, were prepared by the standard ceramic technique. The samples were examined using the techniques; XRD, FT-IR, SEM and VSM. The average lattice parameter showed dependence on x, whereas the crystallite and grain size and strain did not. The infrared spectra showed six absorption bands in the range of 200–1000 cm{sup −1}. They were assigned to the corresponding metallic ion–oxygen bonds among the A- and B-sites. The absorption bands ν{sub 1} and ν{sub 2} and their intensities and force constants F{sub 1} and F{sub 2} were increased against x. Using the transmitted and absorbed energy, the IR velocity and refractive index and jump rate of vacancies were determined and discussed as functions of x. The trend of sauration magnetization Ms was decreased with x, whereas that of coercivity and anisotropy constant was increased. The determined Debye temperature and stiffness constant of the samples were discussed as functions of x. The absorption bands ν{sub 1} and ν{sub 2} proved dependence on the distance between magnetic ions (hopping length) L{sub A-A} and L{sub B-B} at the A- and B-sites, respectively, whereas F{sub 1} and F{sub 2} proved dependence on Ms. - Highlights: • Trend of Ms showed decrease with x, whereas that of Hc and K showed increase. • IR velocity and refractive index and jump rate of vacancies revealed dependence on x. • Debye temperature and stiffness constant showed increase with the additional factor x. • IR bands ν{sub 1} and ν{sub 2} were decreased with the distance between magnetic ions L{sub A} and L{sub B}. • Force constants F{sub 1} and F{sub 2} were affected by the saturation magnetization Ms.

  19. Irrigated Grassland Monitoring Using a Time Series of TerraSAR-X and COSMO-SkyMed X-Band SAR Data

    Directory of Open Access Journals (Sweden)

    Mohammad El Hajj

    2014-10-01

    Full Text Available The objective of this study was to analyze the sensitivity of radar signals in the X-band in irrigated grassland conditions. The backscattered radar signals were analyzed according to soil moisture and vegetation parameters using linear regression models. A time series of radar (TerraSAR-X and COSMO-SkyMed and optical (SPOT and LANDSAT images was acquired at a high temporal frequency in 2013 over a small agricultural region in southeastern France. Ground measurements were conducted simultaneously with the satellite data acquisitions during several grassland growing cycles to monitor the evolution of the soil and vegetation characteristics. The comparison between the Normalized Difference Vegetation Index (NDVI computed from optical images and the in situ Leaf Area Index (LAI showed a logarithmic relationship with a greater scattering for the dates corresponding to vegetation well developed before the harvest. The correlation between the NDVI and the vegetation parameters (LAI, vegetation height, biomass, and vegetation water content was high at the beginning of the growth cycle. This correlation became insensitive at a certain threshold corresponding to high vegetation (LAI ~2.5 m2/m2. Results showed that the radar signal depends on variations in soil moisture, with a higher sensitivity to soil moisture for biomass lower than 1 kg/m². HH and HV polarizations had approximately similar sensitivities to soil moisture. The penetration depth of the radar wave in the X-band was high, even for dense and high vegetation; flooded areas were visible in the images with higher detection potential in HH polarization than in HV polarization, even for vegetation heights reaching 1 m. Lower sensitivity was observed at the X-band between the radar signal and the vegetation parameters with very limited potential of the X-band to monitor grassland growth. These results showed that it is possible to track gravity irrigation and soil moisture variations from SAR

  20. Nonlinear photoluminescence of graded band-gap Al sub x Ga sub 1 sub - sub x As solid solutions

    CERN Document Server

    Kovalenko, V F; Shutov, S V

    2002-01-01

    The dependence of the photoluminescence (PL) intensity of undoped and doped graded band-gap Al sub x Ga sub 1 sub - sub x As (x <= 0.36) solid solutions on the excitation level J (1 x 10 sup 1 sup 9 <= J <= 1 x 10 sup 2 sup 2 quantum cm sup - sup 2 s) for different values of built-in quasi-electrical field E (85 <= E <= 700 V/cm) has been studied. It is found that the dependence of the near-band-edge PL intensity I in the excitation level J at an accelerating action of the field E has a complex character. The nonlinearity of I(J) dependence is explained by contribution of the two-photon absorption of the radiating recombination in the process of its remission. The optimum range of E values (120 <= E <= 200 V/cm) providing the greatest contribution of the two-photon absorption in the reemission in undoped solid solutions is determined

  1. Computer-Automated Evolution of Spacecraft X-Band Antennas

    Science.gov (United States)

    Lohn, Jason D.; Homby, Gregory S.; Linden, Derek S.

    2010-01-01

    A document discusses the use of computer- aided evolution in arriving at a design for X-band communication antennas for NASA s three Space Technology 5 (ST5) satellites, which were launched on March 22, 2006. Two evolutionary algorithms, incorporating different representations of the antenna design and different fitness functions, were used to automatically design and optimize an X-band antenna design. A set of antenna designs satisfying initial ST5 mission requirements was evolved by use these algorithms. The two best antennas - one from each evolutionary algorithm - were built. During flight-qualification testing of these antennas, the mission requirements were changed. After minimal changes in the evolutionary algorithms - mostly in the fitness functions - new antenna designs satisfying the changed mission requirements were evolved and within one month of this change, two new antennas were designed and prototypes of the antennas were built and tested. One of these newly evolved antennas was approved for deployment on the ST5 mission, and flight-qualified versions of this design were built and installed on the spacecraft. At the time of writing the document, these antennas were the first computer-evolved hardware in outer space.

  2. Phase and group velocities for Lamb waves in DOP-26 iridium alloy sheet

    International Nuclear Information System (INIS)

    Simpson, W.A.; McGuire, D.J.

    1994-07-01

    The relatively coarse grain structure of iridium weldments limits the ultrasonic inspection of these structures to frequencies in the low megahertz range. As the material thickness is nominally 0.635 mm for clad vent set capsules, the low frequencies involved necessarily entail the generation of Lamb waves m the specimen. These waves are, of course, dispersive and detailed knowledge of both the phase and group velocities is required in order to determine accurately the location of flaws detected using Lamb waves. Purpose of this study is to elucidate the behavior of Lamb waves propagating in the capsule alloy and to quantify the velocities so that accurate flaw location is ensured. We describe a numerical technique for computing the phase velocities of Lamb waves (or of any other type of guided wave) and derive the group velocities from this information. A frequency-domain method is described for measuring group velocity when multiple Lamb modes are present and mutually interfering in the time domain, and experimental confirmation of the group velocity is presented for the capsule material

  3. Reformulated tight binding calculation for band discontinuity at CdTe/Hg xCd1-xTe heterointerfaces and their type I-type III transitions

    International Nuclear Information System (INIS)

    Ekpunobi, A.J.

    2005-01-01

    A recently reformulated tight binding method is used to calculate the valence band discontinuity at the CdTe/Hg x Cd 1-x Te interface in the s 2 p 2 configuration. The calculated valence band discontinuity of 0.31 eV at CdTe/HgTe interface is in good agreement with self-consistent calculation and accepted experimental value. Calculations were extended to alloy interfaces, which enabled the investigation of the band-offset problem at the transition point. Both valence band discontinuity ratio and conduction band discontinuity ratio show inflexions at the transition point

  4. Rayleigh wave group velocity and shear wave velocity structure in the San Francisco Bay region from ambient noise tomography

    Science.gov (United States)

    Li, Peng; Thurber, Clifford

    2018-06-01

    We derive new Rayleigh wave group velocity models and a 3-D shear wave velocity model of the upper crust in the San Francisco Bay region using an adaptive grid ambient noise tomography algorithm and 6 months of continuous seismic data from 174 seismic stations from multiple networks. The resolution of the group velocity models is 0.1°-0.2° for short periods (˜3 s) and 0.3°-0.4° for long periods (˜10 s). The new shear wave velocity model of the upper crust reveals a number of important structures. We find distinct velocity contrasts at the Golden Gate segment of the San Andreas Fault, the West Napa Fault, central part of the Hayward Fault and southern part of the Calaveras Fault. Low shear wave velocities are mainly located in Tertiary and Quaternary basins, for instance, La Honda Basin, Livermore Valley and the western and eastern edges of Santa Clara Valley. Low shear wave velocities are also observed at the Sonoma volcanic field. Areas of high shear wave velocity include the Santa Lucia Range, the Gabilan Range and Ben Lomond Plutons, and the Diablo Range, where Franciscan Complex or Silinian rocks are exposed.

  5. Crossover and valence bandX-rays of chromium oxides

    International Nuclear Information System (INIS)

    Fazinic, Stjepko; Mandic, Luka; Kavcic, Matjaz; Bozicevic, Iva

    2011-01-01

    X-ray spectra of chromium metal and selected chromium oxides were measured twice using medium resolution flat crystal spectrometer and high resolution spectrometer employing Johansson geometry after excitation with 2 MeV proton beams. The positions and intensities of crossover (Kβ'') and valence (Kβ 2,5 ) band X-rays relative to the primary Kβ X-ray components were extracted in a consistent way. The results were compared with the existing data obtained by proton and photon induced ionization mechanisms and theoretical predictions. The obtained results in peak relative positions and intensities were analyzed in order to study dependence on the chromium oxidation states and chromium-oxygen bond lengths in selected chromium oxides. Our results obtained by both spectrometers confirm that the linear trend observed for the valence peak relative energy shift as a function of chromium oxidation number does not depend on the experimental resolution. Experimental results for normalized intensities (i.e. relative intensities divided with the number of chromium-oxygen pairs) of crossover and valence band X-rays obtained by both spectrometers are in very good agreement, and follow exponential relationship with the average Cr-O bond lengths in corresponding chromium oxides. The observed trends in crossover and valence X-rays normalized intensities could be used to measure the average chromium-oxygen bond length in various chromium oxides, with the sum of both crossover and valence X-ray normalized intensities being the most sensitive measure.

  6. Mini-RF S- and X-band Bistatic Observations of the Floor of Cabeus Crater

    Science.gov (United States)

    Patterson, Gerald Wesley; Stickle, Angela; Turner, Franklin; Jensen, James; Cahill, Joshua; Mini-RF Team

    2017-10-01

    The Mini-RF instrument aboard NASA’s Lunar Reconnaissance Orbiter (LRO) is a hybrid dual-polarized synthetic aperture radar (SAR) and operates in concert with the Arecibo Observatory (AO) and the Goldstone deep space communications complex 34 meter antenna DSS-13 to collect S- and X-band bistatic radar data of the Moon. Bistatic radar data provide a means to probe the near subsurface for the presence of water ice, which exhibits a strong response in the form of a Coherent Backscatter Opposition Effect (CBOE). This effect has been observed in radar data for the icy surfaces of the Galilean satellites, the polar caps of Mars, polar craters on Mercury, and terrestrial ice sheets in Greenland. Previous work using Mini-RF S-band (12.6 cm) bistatic data suggests the presence of a CBOE associated with the floor of the lunar south polar crater Cabeus. The LRO spacecraft has begun its third extended mission. For this phase of operations Mini-RF is leveraging the existing AO architecture to make S-band radar observations of additional polar craters (e.g., Haworth, Shoemaker, Faustini). The purpose of acquiring these data is to determine whether other polar craters exhibit the response observed for Cabeus. Mini-RF has also initiated a new mode of operation that utilizes the X-band (4.2cm) capability of the instrument receiver and a recently commissioned X/C-band transmitter within the Deep Space Network’s (DSN) Goldstone complex to collect bistatic X-band data of the Moon. The purpose of acquiring these data is to constrain the depth/thickness of materials that exhibit a CBOE response - with an emphasis on observing the floor of Cabeus. Recent Mini-RF X-band observations of the floors of the craters Cabeus do not show evidence for a CBOE. This would suggest that the upper ~0.5 meters of the regolith for the floor of Cabeus do not harber water ice in a form detectable at 4.2 cm wavelengths.

  7. Effect of Γ-X band mixing on the donor binding energy in a Quantum Wire

    Science.gov (United States)

    Vijaya Shanthi, R.; Jayakumar, K.; Nithiananthi, P.

    2015-02-01

    To invoke the technological applications of heterostructure semiconductors like Quantum Well (QW), Quantum Well Wire (QWW) and Quantum Dot (QD), it is important to understand the property of impurity energy which is responsible for the peculiar electronic & optical behavior of the Low Dimensional Semiconductor Systems (LDSS). Application of hydrostatic pressure P>35kbar drastically alters the band offsets leading to the crossover of Γ band of the well & X band of the barrier resulting in an indirect transition of the carrier and this effect has been studied experimentally and theoretically in a QW structure. In this paper, we have investigated the effect of Γ-X band mixing due to the application of hydrostatic pressure in a GaAs/AlxGa1-xAs QWW system. The results are presented and discussed for various widths of the wire.

  8. Experimental observation of G banding verifying X-ray workers' chromosome translocation detected by FISH

    International Nuclear Information System (INIS)

    Sun Yuanming; Li Jin; Wang Qin; Tang Weisheng; Wang Zhiquan

    2002-01-01

    Objective: FISH is the most effective way of detecting chromosome aberration and many factors affect its accuracy. G-banding is used to verify the results of early X-ray workers' chromosome translocation examined by FISH. Methods: The chromosome translocations of early X-ray workers have been analysed by FISH (fluorescence in situ hybridization) and G-banding, yields of translocation treated with statistics. Results: The chromosome aberrations frequencies by tow methods are closely related. Conclusion: FISH is a feasible way to analyse chromosome aberrations of X-ray workers and reconstruct dose

  9. Estimating tropical forest structure using LIDAR AND X-BAND INSAR

    Science.gov (United States)

    Palace, M. W.; Treuhaft, R. N.; Keller, M. M.; Sullivan, F.; Roberto dos Santos, J.; Goncalves, F. G.; Shimbo, J.; Neumann, M.; Madsen, S. N.; Hensley, S.

    2013-12-01

    Tropical forests are considered the most structurally complex of all forests and are experiencing rapid change due to anthropogenic and climatic factors. The high carbon stocks and fluxes make understanding tropical forests highly important to both regional and global studies involving ecosystems and climate. Large and remote areas in the tropics are prime targets for the use of remotely sensed data. Radar and lidar have previously been used to estimate forest structure, with an emphasis on biomass. These two remote sensing methods have the potential to yield much more information about forest structure, specifically through the use of X-band radar and waveform lidar data. We examined forest structure using both field-based and remotely sensed data in the Tapajos National Forest, Para, Brazil. We measured multiple structural parameters for about 70 plots in the field within a 25 x 15 km area that have TanDEM-X single-pass horizontally and vertically polarized radar interferometric data. High resolution airborne lidar were collected over a 22 sq km portion of the same area, within which 33 plots were co-located. Preliminary analyses suggest that X-band interferometric coherence decreases by about a factor of 2 (from 0.95 to 0.45) with increasing field-measured vertical extent (average heights of 7-25 m) and biomass (10-430 Mg/ha) for a vertical wavelength of 39 m, further suggesting, as has been observed at C-band, that interferometric synthetic aperture radar (InSAR) is substantially more sensitive to forest structure/biomass than SAR. Unlike InSAR coherence versus biomass, SAR power at X-band versus biomass shows no trend. Moreover, airborne lidar coherence at the same vertical wavenumbers as InSAR is also shown to decrease as a function of biomass, as well. Although the lidar coherence decrease is about 15% more than the InSAR, implying that lidar penetrates more than InSAR, these preliminary results suggest that X-band InSAR may be useful for structure and

  10. Structural phase change and optical band gap bowing in hot wall deposited CdSe{sub x}Te{sub 1-x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Muthukumarasamy, N. [Department of Physics, Coimbatore Institute of Technology, Coimbatore, Tamilnadu (India); Jayakumar, S.; Kannan, M.D.; Balasundaraprabhu, R. [Thin Film Center, PSG College of Technology, Coimbatore, Tamilnadu (India)

    2009-04-15

    CdSe{sub x}Te{sub 1-x} thin films of different compositions have been deposited on glass substrates by hot wall deposition method under conditions very close to thermodynamical equilibrium with minimum loss of material. The structural studies carried out on the deposited films revealed that they are crystalline in nature and exhibit either cubic zinc blende or hexagonal phase or both depending on the composition of the material. The lattice parameter values for both cubic and hexagonal phases have been determined and are observed to vary with composition according to Vegard's law. The optical properties of the deposited CdSe{sub x}Te{sub 1-x} thin films have been studied using transmittance spectra. The spectra shows a sharp fall in transmittance at wavelength corresponding to the band gap of the material. The optical band gap has been determined and found to be direct allowed. The band gap has been observed to strongly depend on film composition. The variation of band gap with composition has been observed to be quadratic in nature exhibiting a bowing behaviour. (author)

  11. Studies of a powerful PPM focused X-band klystron

    International Nuclear Information System (INIS)

    Avrakhov, P.; Balakin, V.; Chashurin, V.

    1998-01-01

    Results of computer simulation and testing of the powerful X band klystron with phase-pulse modulation are presented. The klystron was developed for KEK synchrotron. The simulation efficiency of the klystron is smaller than the testing one. The parasitic oscillations are detected in the klystron, and it is necessary to suppress them [ru

  12. SRTM mission-cross comparison of X adn C band data properties

    Science.gov (United States)

    Rosen, P.; Eineder, M.; Rabus, B.; Gurrola, E.; Hensley, S.; Knopfle, W.; Breit, H.; Roth, A.; Werner, M.

    2001-01-01

    This paper compares the specific properties of the X and C band data sets with respect to global coverage, height accuracy, sensor specific errors, product definition, product format and availability.

  13. Kaolinite: Defect defined material properties – A soft X-ray and first principles study of the band gap

    Energy Technology Data Exchange (ETDEWEB)

    Pietzsch, A., E-mail: annette.pietzsch@helmholtz-berlin.de [Institute for Methods and Instrumentation in Synchrotron Radiation Research G-ISRR, Helmholtz-Zentrum für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Nisar, J. [Pakistan Atomic Energy Commission (PAEC), P.O. Box 2151, Islamabad (Pakistan); Jämstorp, E. [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Gråsjö, J. [Department of Pharmacy, Uppsala University, Box 580, 75123 Uppsala (Sweden); Århammar, C. [Coromant R& D, S-126 80 Stockholm (Sweden); Ahuja, R.; Rubensson, J.-E. [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden)

    2015-07-15

    Highlights: • The respective electronic structure of synthetic and natural kaolinite is compared. • The size of the band gap and thus many important material properties are defined by defect states in the band gap. • The oxygen-based defect states are identified and analyzed. • The band gap of kaolinite decreases significantly due to the forming of defects. - Abstract: By combining X-ray absorption spectroscopy and first principles calculations we have determined the electronic structure of synthetic and natural kaolinite as a model system for engineered and natural clay materials. We have analyzed defect states in the band gap and find that both natural and synthetic kaolinite contain defects where oxygen replaces hydrogen in one of the Al (0 0 1)-hydroxyl groups of the kaolinite clay sheets. The band gap of both synthetic and natural kaolinite is found to decrease by about 3.2 eV as this defect is formed.

  14. Kaolinite: Defect defined material properties – A soft X-ray and first principles study of the band gap

    International Nuclear Information System (INIS)

    Pietzsch, A.; Nisar, J.; Jämstorp, E.; Gråsjö, J.; Århammar, C.; Ahuja, R.; Rubensson, J.-E.

    2015-01-01

    Highlights: • The respective electronic structure of synthetic and natural kaolinite is compared. • The size of the band gap and thus many important material properties are defined by defect states in the band gap. • The oxygen-based defect states are identified and analyzed. • The band gap of kaolinite decreases significantly due to the forming of defects. - Abstract: By combining X-ray absorption spectroscopy and first principles calculations we have determined the electronic structure of synthetic and natural kaolinite as a model system for engineered and natural clay materials. We have analyzed defect states in the band gap and find that both natural and synthetic kaolinite contain defects where oxygen replaces hydrogen in one of the Al (0 0 1)-hydroxyl groups of the kaolinite clay sheets. The band gap of both synthetic and natural kaolinite is found to decrease by about 3.2 eV as this defect is formed

  15. X-ray emission from clusters and groups of galaxies

    Science.gov (United States)

    Mushotzky, R.

    1998-01-01

    Recent major advances in x-ray imaging and spectroscopy of clusters have allowed the determination of their mass and mass profile out to approximately 1/2 the virial radius. In rich clusters, most of the baryonic mass is in the gas phase, and the ratio of mass in gas/stars varies by a factor of 2-4. The baryonic fractions vary by a factor of approximately 3 from cluster to cluster and almost always exceed 0.09 h50-[3/2] and thus are in fundamental conflict with the assumption of Omega = 1 and the results of big bang nucleosynthesis. The derived Fe abundances are 0.2-0.45 solar, and the abundances of O and Si for low redshift systems are 0.6-1.0 solar. This distribution is consistent with an origin in pure type II supernova. The amount of light and energy produced by these supernovae is very large, indicating their importance in influencing the formation of clusters and galaxies. The lack of evolution of Fe to a redshift of z approximately 0.4 argues for very early enrichment of the cluster gas. Groups show a wide range of abundances, 0.1-0.5 solar. The results of an x-ray survey indicate that the contribution of groups to the mass density of the universe is likely to be larger than 0.1 h50-2. Many of the very poor groups have large x-ray halos and are filled with small galaxies whose velocity dispersion is a good match to the x-ray temperatures.

  16. Quantitative analysis of X-band weather radar attenuation correction accuracy

    NARCIS (Netherlands)

    Berne, A.D.; Uijlenhoet, R.

    2006-01-01

    At short wavelengths, especially C-, X-, and K-band, weather radar signals arc attenuated by the precipitation along their paths. This constitutes a major source of error for radar rainfall estimation, in particular for intense precipitation. A recently developed stochastic simulator of range

  17. An Empirical Algorithm for Wave Retrieval from Co-Polarization X-Band SAR Imagery

    Directory of Open Access Journals (Sweden)

    Weizeng Shao

    2017-07-01

    Full Text Available In this study, we proposed an empirical algorithm for significant wave height (SWH retrieval from TerraSAR-X/TanDEM (TS-X/TD-X X-band synthetic aperture radar (SAR co-polarization (vertical-vertical (VV and horizontal-horizontal (HH images. As the existing empirical algorithm at X-band, i.e., XWAVE, is applied for wave retrieval from HH-polarization TS-X/TD-X image, polarization ratio (PR has to be used for inverting wind speed, which is treated as an input in XWAVE. Wind speed encounters saturation in tropical cyclone. In our work, wind speed is replaced by normalized radar cross section (NRCS to avoiding using SAR-derived wind speed, which does not work in high winds, and the empirical algorithm can be conveniently implemented without converting NRCS in HH-polarization to NRCS in VV-polarization by using X-band PR. A total of 120 TS-X/TD-X images, 60 in VV-polarization and 60 in HH-polarization, with homogenous wave patterns, and the coincide significant wave height data from European Centre for Medium-Range Weather Forecasts (ECMWF reanalysis field at a 0.125° grid were collected as a dataset for tuning the algorithm. The range of SWH is from 0 to 7 m. We then applied the algorithm to 24 VV and 21 HH additional SAR images to extract SWH at locations of 30 National Oceanic and Atmospheric Administration (NOAA National Data Buoy Center (NDBC buoys. It is found that the algorithm performs well with a SWH stander deviation (STD of about 0.5 m for both VV and HH polarization TS-X/TD-X images. For large wave validation (SWH 6–7 m, we applied the empirical algorithm to a tropical cyclone Sandy TD-X image acquired in 2012, and obtained good result with a SWH STD of 0.3 m. We concluded that the proposed empirical algorithm works for wave retrieval from TS-X/TD-X image in co-polarization without external sea surface wind information.

  18. Marine X-band Weather Radar Data Calibration

    DEFF Research Database (Denmark)

    Thorndahl, Søren Liedtke; Rasmussen, Michael R.

    2012-01-01

    estimates. This paper presents some of the challenges in small marine X-band radar calibration by comparing three calibration procedures for assessing the relationship between radar and rain gauge data. Validation shows similar results for precipitation volumes but more diverse results on peak rain......Application of weather radar data in urban hydrology is evolving and radar data is now applied for both modelling, analysis, and real time control purposes. In these contexts, it is allimportant that the radar data is well calibrated and adjusted in order to obtain valid quantitative precipitation...

  19. X-BAND LINEAR COLLIDER R and D IN ACCELERATING STRUCTURES THROUGH ADVANCED COMPUTING

    International Nuclear Information System (INIS)

    Li, Z

    2004-01-01

    This paper describes a major computational effort that addresses key design issues in the high gradient accelerating structures for the proposed X-band linear collider, GLC/NLC. Supported by the US DOE's Accelerator Simulation Project, SLAC is developing a suite of parallel electromagnetic codes based on unstructured grids for modeling RF structures with higher accuracy and on a scale previously not possible. The new simulation tools have played an important role in the R and D of X-Band accelerating structures, in cell design, wakefield analysis and dark current studies

  20. Results from the CLIC X-Band Structure Test Program at NLCTA

    International Nuclear Information System (INIS)

    Adolphsen, C.

    2009-01-01

    As part of a SLAC-CERN-KEK collaboration on high gradient X-band structure research, several prototype structures for the CLIC linear collider study have been tested using two of the high power (300 MW) X-band rf stations in the NLCTA facility at SLAC. These structures differ in terms of their fabrication (brazed disks and clamped quadrants), gradient profile (amount by which the gradient increases along the structure, which optimizes efficiency and maximizes sustainable gradient) and HOM damping (use of slots or waveguides to rapidly dissipate dipole mode energy). The CLIC goal in the next few years is to demonstrate the feasibility of a CLIC-ready baseline design and to investigate alternatives that could increase efficiency. This paper summarizes the high gradient test results from NLCTA in support of this effort.

  1. Bulk band gaps in divalent hexaborides: A soft x-ray emission study

    International Nuclear Information System (INIS)

    Denlinger, Jonathan D.; Gweon, Gey-Hong; Allen, James W.; Bianchi, Andrea D.; Fisk, Zachary

    2001-01-01

    Boron K-edge soft x-ray emission and absorption are used to address the fundamental question of whether divalent hexaborides are intrinsic semimetals or defect-doped bandgap insulators. These bulk sensitive measurements, complementary and consistent with surface-sensitive angle-resolved photoemission experiments, confirm the existence of a bulk band gap and the location of the chemical potential at the bottom of the conduction band

  2. THE VELOCITY DISTRIBUTION OF NEARBY STARS FROM HIPPARCOS DATA. II. THE NATURE OF THE LOW-VELOCITY MOVING GROUPS

    International Nuclear Information System (INIS)

    Bovy, Jo; Hogg, David W.

    2010-01-01

    The velocity distribution of nearby stars (∼<100 pc) contains many overdensities or 'moving groups', clumps of comoving stars, that are inconsistent with the standard assumption of an axisymmetric, time-independent, and steady-state Galaxy. We study the age and metallicity properties of the low-velocity moving groups based on the reconstruction of the local velocity distribution in Paper I of this series. We perform stringent, conservative hypothesis testing to establish for each of these moving groups whether it could conceivably consist of a coeval population of stars. We conclude that they do not: the moving groups are neither trivially associated with their eponymous open clusters nor with any other inhomogeneous star formation event. Concerning a possible dynamical origin of the moving groups, we test whether any of the moving groups has a higher or lower metallicity than the background population of thin disk stars, as would generically be the case if the moving groups are associated with resonances of the bar or spiral structure. We find clear evidence that the Hyades moving group has higher than average metallicity and weak evidence that the Sirius moving group has lower than average metallicity, which could indicate that these two groups are related to the inner Lindblad resonance of the spiral structure. Further, we find weak evidence that the Hercules moving group has higher than average metallicity, as would be the case if it is associated with the bar's outer Lindblad resonance. The Pleiades moving group shows no clear metallicity anomaly, arguing against a common dynamical origin for the Hyades and Pleiades groups. Overall, however, the moving groups are barely distinguishable from the background population of stars, raising the likelihood that the moving groups are associated with transient perturbations.

  3. A 1Σ+ → X 1Σ+ bands of the isotopic lithium hydrides

    International Nuclear Information System (INIS)

    Li, K.C.; Stwalley, W.C.

    1977-01-01

    In order to obtain a better understanding of the X 1 Σ + ground state and the A 1 Σ + state potential energy curves of lithium hydride and to examine in detail the concept of ''mass-reduced quantum numbers'' for both an ordinary (X 1 Σ + ) and an anomalous (A 1 Σ + ) electronic state, the emission spectra of the A 1 Σ + → X 1 Σ + bands of the isotopic lithium hydrides and deuterides ere photographed in the 3000 to 5000A region with a 3.4 meter Ebert Spectrograph. The bands found involved v'' = 0 to 7 to various v' = 0 to 17 for 6 LiH, and v'' = 0 to 7 to various v' = 1 to 16 for 6 LiD. Additional bands involving v'' = 4 and 5 were also found for 7 LiH. The vibrational-rotational spectroscopic analysis of 7 LiH, 6 LiH and 6 LiD are reported here, as are the reanalyses of the 7 LiH and 7 LiD data reported by Crawford and Jorgensen. New Rydberg-Klein-Rees (RKR) A 1 Σ + and X 1 Σ + potential curves have been constructed for each individual molecule and are reported, but detailed isotopic comparisons will be reported in subsequent publications

  4. Dynamics of isolated magnetic bright points derived from Hinode/SOT G-band observations

    Science.gov (United States)

    Utz, D.; Hanslmeier, A.; Muller, R.; Veronig, A.; Rybák, J.; Muthsam, H.

    2010-02-01

    Context. Small-scale magnetic fields in the solar photosphere can be identified in high-resolution magnetograms or in the G-band as magnetic bright points (MBPs). Rapid motions of these fields can cause magneto-hydrodynamical waves and can also lead to nanoflares by magnetic field braiding and twisting. The MBP velocity distribution is a crucial parameter for estimating the amplitudes of those waves and the amount of energy they can contribute to coronal heating. Aims: The velocity and lifetime distributions of MBPs are derived from solar G-band images of a quiet sun region acquired by the Hinode/SOT instrument with different temporal and spatial sampling rates. Methods: We developed an automatic segmentation, identification and tracking algorithm to analyse G-Band image sequences to obtain the lifetime and velocity distributions of MBPs. The influence of temporal/spatial sampling rates on these distributions is studied and used to correct the obtained lifetimes and velocity distributions for these digitalisation effects. Results: After the correction of algorithm effects, we obtained a mean MBP lifetime of (2.50 ± 0.05) min and mean MBP velocities, depending on smoothing processes, in the range of (1-2) km~s-1. Corrected for temporal sampling effects, we obtained for the effective velocity distribution a Rayleigh function with a coefficient of (1.62 ± 0.05) km~s-1. The x- and y-components of the velocity distributions are Gaussians. The lifetime distribution can be fitted by an exponential function.

  5. Spin excitation and band-narrowing in Al{sub x}Ga{sub 1-x}As heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M. Idrish, E-mail: m.miah@griffith.edu.au [Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

    2010-11-01

    We studied the spin excitation in dependences of the applied electric field and lattice temperature (LT) via the measurements of the circularly polarized photoluminescence (CPPL) in Al{sub x}Ga{sub 1-x}As heterostructures (HSs). The intensity of CPPL was found to strongly depend on the electric field applied to the HSs. The CPPL was also found to enhance with decreasing LT. It was demonstrated that the observed LT dependence might be due to the LT-dependent band-gap shift of the HS materials.

  6. X-ray emission from clusters and groups of galaxies

    Science.gov (United States)

    Mushotzky, Richard

    1998-01-01

    Recent major advances in x-ray imaging and spectroscopy of clusters have allowed the determination of their mass and mass profile out to ≈1/2 the virial radius. In rich clusters, most of the baryonic mass is in the gas phase, and the ratio of mass in gas/stars varies by a factor of 2–4. The baryonic fractions vary by a factor of ≈3 from cluster to cluster and almost always exceed 0.09 h50−[3/2] and thus are in fundamental conflict with the assumption of Ω = 1 and the results of big bang nucleosynthesis. The derived Fe abundances are 0.2–0.45 solar, and the abundances of O and Si for low redshift systems are 0.6–1.0 solar. This distribution is consistent with an origin in pure type II supernova. The amount of light and energy produced by these supernovae is very large, indicating their importance in influencing the formation of clusters and galaxies. The lack of evolution of Fe to a redshift of z ≈ 0.4 argues for very early enrichment of the cluster gas. Groups show a wide range of abundances, 0.1–0.5 solar. The results of an x-ray survey indicate that the contribution of groups to the mass density of the universe is likely to be larger than 0.1 h50−2. Many of the very poor groups have large x-ray halos and are filled with small galaxies whose velocity dispersion is a good match to the x-ray temperatures. PMID:9419327

  7. Band theory of metals the elements

    CERN Document Server

    Altmann, Simon L

    1970-01-01

    Band Theory of Metals: The Elements focuses on the band theory of solids. The book first discusses revision of quantum mechanics. Topics include Heisenberg's uncertainty principle, normalization, stationary states, wave and group velocities, mean values, and variational method. The text takes a look at the free-electron theory of metals, including heat capacities, density of states, Fermi energy, core and metal electrons, and eigenfunctions in three dimensions. The book also reviews the effects of crystal fields in one dimension. The eigenfunctions of the translations; symmetry operations of t

  8. On the evolution of magnetic and velocity fields of an originating sunspot group

    International Nuclear Information System (INIS)

    Bachmann, G.

    1978-01-01

    Magnetographic measurements were made to derive longitudinal magnetic field strengths, line-of-sight velocities and the brightness distribution in an originating sunspot group. These results and photographs of the group are used to compare the evaluation of a relatively simple active region with our present ideas about the evolution of active regions in general. We found that the total magnetic flux increased from about 4 to 20x10 20 Mx over three days. The downward flow of gas in regions with stronger magnetic fields is formed only after the magnetic field has already been bipolar for two days. The maximum velocity always occurred in the main spots of the preceding and the subsequent parts of the sunspot group. Transformation into a flow pattern, which looks like Evershed motion, is observed in the main preceding sunspot after the formation of the penumbra. The generation of new active regions by concentration and amplification of magnetic fields, under the action of supergranulation flow in photospheric layers, cannot play an important role. On the contrary, the behaviour of the active region is in agreement with the conception of rising flux tubes, out of which the gas flows down. Our observations confirm that a magnetic field strength, leading to the generation of sunspots, is attained earlier in the preceding part of the originating active region than in its subsequent part. A series of subflares occurred in the active region, when short-lived small magnetic structure elements emerged in the larger bipolar magnetic field. (author)

  9. Microwave frequency detector at X-band using GaAs MMIC technology

    International Nuclear Information System (INIS)

    Zhang Jun; Liao Xiaoping; Jiao Yongchang

    2009-01-01

    The design, fabrication, and experimental results of an MEMS microwave frequency detector are presented for the first time. The structure consists of a microwave power divider, two CPW transmission lines, a microwave power combiner, an MEMS capacitive power sensor and a thermopile. The detector has been designed and fabricated on GaAs substrate using the MMIC process at the X-band successfully. The MEMS capacitive power sensor is used for detecting the high power signal, while the thermopile is used for detecting the low power signal. Signals of 17 and 10 dBm are measured over the X-band. The sensitivity is 0.56 MHz/fF under 17 dBm by the capacitive power sensor, and 6.67 MHz/μV under 10 dBm by the thermopile, respectively. The validity of the presented design has been confirmed by the experiment.

  10. Reformulated tight binding calculation for band discontinuity at CdTe/Hg {sub x}Cd{sub 1-x}Te heterointerfaces and their type I-type III transitions

    Energy Technology Data Exchange (ETDEWEB)

    Ekpunobi, A.J. [Department of Physics and Industrial Physics, Nnamdi Azikiwe University, P.M.B. 5025, Awka, Anambra State (Nigeria)

    2005-02-25

    A recently reformulated tight binding method is used to calculate the valence band discontinuity at the CdTe/Hg {sub x}Cd{sub 1-x}Te interface in the s{sup 2}p{sup 2} configuration. The calculated valence band discontinuity of 0.31 eV at CdTe/HgTe interface is in good agreement with self-consistent calculation and accepted experimental value. Calculations were extended to alloy interfaces, which enabled the investigation of the band-offset problem at the transition point. Both valence band discontinuity ratio and conduction band discontinuity ratio show inflexions at the transition point.

  11. Analysis of high resolution land clutter using an X-band radar

    CSIR Research Space (South Africa)

    Melebari, A

    2015-10-01

    Full Text Available . Measurements were performed with an X-band radar system with two instantaneous bandwidths of 40 MHz and 400 MHz. The clutter data was analyzed by fitting the amplitude Probability Distribution Function (PDF) to different distributions using the Method...

  12. Anomalous group velocity at the high energy range of real 3D photonic nanostructures

    Science.gov (United States)

    Botey, Muriel; Martorell, Jordi; Lozano, Gabriel; Míguez, Hernán; Dorado, Luis A.; Depine, Ricardo A.

    2010-05-01

    We perform a theoretical study on the group velocity for finite thin artificial opal slabs made of a reduced number of layers in the spectral range where the light wavelength is on the order of the lattice parameter. The vector KKR method including extinction allows us to evaluate the finite-size effects on light propagation in the ΓL and ΓX directions of fcc close-packed opal films made of dielectric spheres. The group is index determined from the phase delay introduced by the structure to the forwardly transmitted electric field. We show that for certain frequencies, light propagation can either be superluminal -positive or negative- or approach zero depending on the crystal size and absorption. Such anomalous behavior can be attributed to the finite character of the structure and provides confirmation of recently emerged experimental results.

  13. Effect of Co substitution on absorption properties of SrCoxFe12-xO19 hexagonal ferrites based nanocomposites in X-band

    Science.gov (United States)

    Chakraborty, Soma; Bhattacharyya, Nidhi Saxena; Bhattacharyya, Satyajib

    2017-12-01

    Cobalt doped M-type strontium hexaferrite nanoparticles (SrCoxFe12-xO19, x = 0.2-1.2) is synthesized and used as inclusions in Linear Low Density Polyethylene (LLDPE) matrix for developing nano-composites with 60 wt% of these nanoparticles. Absorption performance of the developed nano-composites is evaluated in the X-band. The thickness optimization is carried out for obtaining maximum reflection loss by using the transmission line model (TLM), with measured values of permittivity and permeability of the composite. The best reflection loss is observed experimentally for x = 0.8 with an absorber thickness of 3 mm for which a wide -10 dB bandwidth covering almost the entire X-band is obtained. The composites are light weight and not affected by exposure to water.

  14. Lunar Noise-Temperature Increase Measurements at S-Band, X-Band, and Ka-Band Using a 34-Meter-Diameter Beam-Waveguide Antenna

    Science.gov (United States)

    Morabito, D. D.

    2006-08-01

    The Moon radiates energy at infrared and microwave wavelengths, in addition to reflecting sunlight at optical wavelengths. As a result, an antenna pointed at or near the Moon will cause an increase in receiver noise temperature that needs to be accounted for in telemetry, radio science, or ranging link budgets. The Deep Space Network may be required to use its antennas in future lunar robotic or human missions, and thus it is important to understand the nature of this temperature increase as a function of observing frequency, lunar phase, and angular offset of the antenna beam from the center of the lunar disk. This article quantifies such a set of measurements acquired at DSS 13, a 34-m-diameter research and development beam-waveguide antenna located at Goldstone, California, at three different telecommunication frequencies, S-band (2.3 GHz), X-band (8.4 GHz), and Ka-band (32 GHz), over a wide range of lunar phase, for both disk-centered and limb-centered positions of the antenna beam.

  15. X-ray doppler velocimetry for diagnosis of fluid motion in ICF implosions

    Science.gov (United States)

    Koch, J. A.; King, J. A.; Huffman, E.; Freeman, R. R.; Dutra, E. C.; Field, J. E.; Kilkenny, J. D.; Hall, G. N.; Harding, E.; Rochau, G. A.; Porter, J. L.; Covington, A. M.; Beg, F. N.

    2017-08-01

    We are developing a novel diagnostic for measurement of bulk fluid motion in materials, that is particularly applicable to very hot, x-ray emitting plasmas in the High Energy Density Physics (HEDP) regime. The X-ray Doppler Velocimetry (XDV) technique relies on monochromatic imaging in multiple x-ray energy bands near the center of an x-ray emission line in a plasma, and utilizes bent imaging crystals. Higher energy bands are preferentially sensitive to plasma moving towards the viewer, while lower energy bands are preferentially sensitive to plasma moving away from the viewer. Combining multiple images in different energy bands allows for a reconstruction of the fluid velocity field integrated along the line of sight. We review the technique, and we discuss progress towards benchmarking the technique with proof-of-principle HEDP experiments.

  16. Forbidden energy band gap in diluted a-Ge1−xSix:N films

    International Nuclear Information System (INIS)

    Guarneros, C.; Rebollo-Plata, B.; Lozada-Morales, R.; Espinosa-Rosales, J.E.; Portillo-Moreno, J.; Zelaya-Angel, O.

    2012-01-01

    By means of electron gun evaporation Ge 1−x Si x :N thin films, in the entire range 0 ≤ x ≤ 1, were prepared on Si (100) and glass substrates. The initial vacuum reached was 6.6 × 10 −4 Pa, then a pressure of 2.7 × 10 −2 Pa of high purity N 2 was introduced into the chamber. The deposition time was 4 min. Crucible-substrate distance was 18 cm. X-ray diffraction patterns indicate that all the films were amorphous (a-Ge 1−x Si x :N). The nitrogen concentration was of the order of 1 at% for all the films. From optical absorption spectra data and by using the Tauc method the energy band gap (E g ) was calculated. The Raman spectra only reveal the presence of Si-Si, Ge-Ge, and Si-Ge bonds. Nevertheless, infrared spectra demonstrate the existence of Si-N and Ge-N bonds. The forbidden energy band gap (E g ) as a function of x in the entire range 0 ≤ x ≤ 1 shows two well defined regions: 0 ≤ x ≤ 0.67 and 0.67 ≤ x ≤ 1, due to two different behaviors of the band gap, where for x > 0.67 exists an abruptly change of E g (x). In this case E g (x) versus x is different to the variation of E g in a-Ge 1−x Si x and a-Ge 1−x Si x :H. This fact can be related to the formation of Ge 3 N 4 and GeSi 2 N 4 when x ≤ 0.67, and to the formation of Si 3 N 4 and GeSi 2 N 4 for 0.67 ≤ x. - Highlights: ► Nitrogen doped amorphous Ge 1-x Si x thin films are grown by electron gun technique. ► Nitrogen atoms on E g of the a-Ge 1-x Si x films in the 0 £ x £ 1 range are analyzed. ► Variation in 0 £ x £ 1 range shows a warped change of E g in 1.0 – 3.6 eV range. ► The change in E g (x) behavior when x ∼ 0.67 was associated with Ge 2 SiN 4 presence.

  17. Solid-State Powered X-band Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Othman, Mohamed A.K. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Nann, Emilio A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Dolgashev, Valery A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Tantawi, Sami [SLAC National Accelerator Lab., Menlo Park, CA (United States); Neilson, Jeff [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2017-03-06

    In this report we disseminate the hot test results of an X-band 100-W solid state amplifier chain for linear accelerator (linac) applications. Solid state power amplifiers have become increasingly attractive solutions for achieving high power in radar and maritime applications. Here the performance of solid state amplifiers when driving an RF cavity is investigated. Commercially available, matched and fully-packaged GaN on SiC HEMTs are utilized, comprising a wideband driver stage and two power stages. The amplifier chain has a high poweradded- efficiency and is able to supply up to ~1.2 MV/m field gradient at 9.2 GHz in a simple test cavity, with a peak power exceeding 100 W. These findings set forth the enabling technology for solid-state powered linacs.

  18. Slow light with low group-velocity dispersion at the edge of photonic graphene

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang Chunfang; Dong Biqin; Liu Xiaohan; Zi Jian [Department of Physics, Key Laboratory of Micro- and Nanophotonic Structures, Ministry of Education, and Key Laboratory of Surface Physics, Fudan University, Shanghai 200433 (China); Xiong Zhiqiang; Zhao Fangyuan; Hu Xinhua [Department of Material Science and Laboratory of Advanced Materials, Fudan University, Shanghai 200433 (China)

    2011-07-15

    We theoretically study the light propagation at the zigzag edges of a honeycomb photonic crystal (PC), or photonic graphene. It is found that the corresponding edge states have a sinusoidal dispersion similar to those found in PC coupled resonator optical waveguides [CROWs; M. Notomi et al., Nature Photon. 2, 741 (2008)]. The sinusoidal dispersion curve can be made very flat by carefully tuning edge parameters. As a result, low group velocity and small group velocity dispersion can be simultaneously obtained for light propagating at the zigzag edge of photonic graphene. Compared with PC CROWs, our slow-light system exhibits no intrinsic radiation loss and has a larger group velocity bandwidth product. Our results could find applications in on-chip optical buffers and enhanced light-matter interaction.

  19. High power tests of X-band RF windows at KEK

    Energy Technology Data Exchange (ETDEWEB)

    Otake, Yuji [Earthquake Research Inst., Tokyo Univ., Tokyo (Japan); Tokumoto, Shuichi; Kazakov, Sergei Yu.; Odagiri, Junichi; Mizuno, Hajime

    1997-04-01

    Various RF windows comprising a short pill-box, a long pill-box, a TW (traveling wave)-mode and three TE11-mode horn types have been developed for an X-band high-power pulse klystron with two output windows for JLC (Japan Linear Collider). The output RF power of the klystron is designed to be 130 MW with the 800 ns pulse duration. Since this X-band klystron has two output windows, the maximum RF power of the window must be over 85 MW. The design principle for the windows is to reduce the RF-power density and/or the electric-field strength at the ceramic part compared with that of an ordinary pill-box-type window. Their reduction is effective to increase the handling RF power of the window. To confirm that the difference among the electric-field strengths depends on their RF structures, High-power tests of the above-mentioned windows were successfully carried out using a traveling-wave resonator (TWR) for the horns and the TW-mode type and, installing them directly to klystron output waveguides for the short and long pill-box type. Based upon the operation experience of S-band windows, two kinds of ceramic materials were used for these tests. The TE11-mode 1/2{lambda}g-1 window was tested up to the RF peak-power of 84 MW with the 700 ns pulse duration in the TWR. (J.P.N)

  20. X-Band Thermionic Cathode RF Gun at UTNL

    CERN Document Server

    Fukasawa, Atsushi; Dobashi, Katsuhiro; Ebina, Futaro; Hayano, Hitoshi; Higo, Toshiyasu; Kaneyasu, Tatsuo; Matsuo, Kennichi; Ogino, Haruyuki; Sakae, Hisaharu; Sakamoto, Fumito; Uesaka, Mitsuru; Urakawa, Junji

    2005-01-01

    The X-band (11.424 GHz) linac for compact Compton scattering hard X-ray source are under construction at Nuclear Engineering Research Laboratory, University of Tokyo. This linac designed to accelerate up to 35 MeV, and this electron beam will be used to produce hard X-ray by colliding with laser. It consists of a thermionic cathode RF gun, an alpha magnet, and a traveling wave tube. The gun has 3.5 cells (unloaded Q is 8250) and will be operated at pi-mode. A dispenser cathode is introduced. Since the energy spread of the beam from the gun is predicted to be broad due to the continuous emission from the thermionic cathode, a slit is placed in the alpha magnet to eliminate low energy electrons. The simulation on the injector shows the beam energy 2.9 MeV, the charge 23 pC/bunch, and the emittance less than 10 mm.mrad. The experiment on the gun is planed in the beginning of 2005, and the details will be discussed on the spot.

  1. Combined Use of C- and X-Band SAR Data for Subsidence Monitoring in an Urban Area

    Directory of Open Access Journals (Sweden)

    Lorenzo Solari

    2017-04-01

    Full Text Available In this study, we present the detection and characterization of ground displacements in the urban area of Pisa (Central Italy using Interferometric Synthetic Aperture Radar (InSAR products. Thirty RADARSAT-2 and twenty-nine COSMO-SkyMed images have been analyzed with the Small BAseline Subset (SBAS algorithm, in order to quantify the ground subsidence and its temporal evolution in the three-year time interval from 2011 to 2014. A borehole database was reclassified in stratigraphical and geotechnical homogeneous units, providing the geological background needed for the local scale analysis of the recorded displacements. Moreover, the interferometric outputs were compared with the last 30 years’ urban evolution of selected parts of the city. Two deformation patterns were recorded by the InSAR data: very slow vertical movements within the defined stability threshold (±2.5 mm/yr and areas with subsidence rates down to −5 to −7 mm/yr, associated with high peak velocities (−15 to −20 mm/yr registered by single buildings or small groups of buildings. Some of these structures are used to demonstrate that the high subsidence rates are related to the recent urbanization, which is the trigger for the accelerated consolidation process of highly compressible layers. Finally, this urban area was a valuable test site for demonstrating the different results of the C- and X-band data processing, in terms of the density of points and the quality of the time series of deformation.

  2. Flood Monitoring using X-band Dual-polarization Radar Network

    Science.gov (United States)

    Chandrasekar, V.; Wang, Y.; Maki, M.; Nakane, K.

    2009-09-01

    A dense weather radar network is an emerging concept advanced by the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA). Using multiple radars observing over a common will create different data outcomes depending on the characteristics of the radar units employed and the network topology. To define this a general framework is developed to describe the radar network space, and formulations are obtained that can be used for weather radar network characterization. Current weather radar surveillance networks are based upon conventional sensing paradigm of widely-separated, standalone sensing systems using long range radars that operate at wavelengths in 5-10 cm range. Such configuration has limited capability to observe close to the surface of the earth because of the earth's curvature but also has poorer resolution at far ranges. The dense network radar system, observes and measures weather phenomenon such as rainfall and severe weather close to the ground at higher spatial and temporal resolution compared to the current paradigm. In addition the dense network paradigm also is easily adaptable to complex terrain. Flooding is one of the most common natural hazards in the world. Especially, excessive development decreases the response time of urban watersheds and complex terrain to rainfall and increases the chance of localized flooding events over a small spatial domain. Successful monitoring of urban floods requires high spatiotemporal resolution, accurate precipitation estimation because of the rapid flood response as well as the complex hydrologic and hydraulic characteristics in an urban environment. This paper reviews various aspects in radar rainfall mapping in urban coverage using dense X-band dual-polarization radar networks. By reducing the maximum range and operating at X-band, one can ensure good azimuthal resolution with a small-size antenna and keep the radar beam closer to the ground. The networked topology helps to achieve satisfactory

  3. Preliminary Analysis of X-Band and Ka-Band Radar for Use in the Detection of Icing Conditions Aloft

    Science.gov (United States)

    Reehorst, Andrew L.; Koenig, George G.

    2004-01-01

    NASA and the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) have an on-going activity to develop remote sensing technologies for the detection and measurement of icing conditions aloft. Radar has been identified as a strong tool for this work. However, since the remote detection of icing conditions with the intent to identify areas of icing hazard is a new and evolving capability, there are no set requirements for radar sensitivity. This work is an initial attempt to quantify, through analysis, the sensitivity requirements for an icing remote sensing radar. The primary radar of interest for cloud measurements is Ka-band, however, since NASA is currently using an X-band unit, this frequency is also examined. Several aspects of radar signal analysis were examined. Cloud reflectivity was calculated for several forms of cloud using two different techniques. The Air Force Geophysical Laboratory (AFGL) cloud models, with different drop spectra represented by a modified gamma distribution, were utilized to examine several categories of cloud formation. Also a fundamental methods approach was used to allow manipulation of the cloud droplet size spectra. And an analytical icing radar simulator was developed to examine the complete radar system response to a configurable multi-layer cloud environment. Also discussed is the NASA vertical pointing X-band radar. The radar and its data system are described, and several summer weather events are reviewed.

  4. Velocity-Resolved [Ne III] from X-Ray Irradiated Sz 102 Microjets

    Science.gov (United States)

    Liu, C.-F.; Shang, H.; Walter, F. M.; Herczeg, G. J.

    2014-03-01

    Neon emission lines are good indicators of high-excitation regions close to a young stellar system because of their high ionization potentials and large critical densities. We have discovered [Ne III] .3869 emission from the microjet of low-mass young star Sz 102. Spectroastrometric analysis of the two-dimensional [Ne III] spectral image obtained from the archival high-dispersion (R - 33,000) Very Large Telescope/UVES spectra suggests that the emission consists of two velocity components spatially separated by ~ 0.''3. The stronger redshifted component is centered at ~ +21 km s-1 with a line width of ~ 140 km s-1, and the weaker blueshifted component at ~ -90 km s-1 with a larger line width of ~ 190 km s-1. Both components have large line widths that extend across the systemic velocity, suggesting their origin from diverging streamlines of a wide-angle wind. Optical line ratio diagnostics indicate that Sz 102 drives a pair of hot (T . 2 ◊ 104 K) and ionized (ne . 2 ◊ 104 cm-3) jets. The blueshifted jet has on average ~ 50% higher temperature and electron density. We suggest that the jet is ionized by an embedded hard X-ray source close to the driving region. Freezing-in of the ionization state is consistent with the flow speed and the Ne2+ recombination timescales. We postulate that these X-rays originate from hard coronae or stellar flares; the hard (keV) X-ray photons ionize neon in the inner wind, while the soft X-rays are mostly absorbed by the accretion funnel. These postulates await validation from high-sensitivity X-ray and subarcsecond resolution optical observations.

  5. The localized effect of the Bi level on the valence band in the dilute bismuth GaBixAs1-x alloy

    Science.gov (United States)

    Zhao, Chuan-Zhen; Zhu, Min-Min; Wang, Jun; Wang, Sha-Sha; Lu, Ke-Qing

    2018-05-01

    The research on the temperature dependence of the band gap energy of the dilute bismuth GaBixAs1-x alloy has been done. It is found that its temperature insensitiveness is due to the enhanced localized character of the valence band state and the small decrease of the temperature coefficient for the conduction band minimum (CBM). The enhanced localized character of the valence band state is the main factor. In order to describe the localized effect of the Bi levels on the valence band, the localized energy is introduced into the Varshni's equation. It is found that the effect of the localized Bi level on the valence band becomes strong with increasing Bi content. In addition, it is found that the pressure dependence of the band gap energy of GaBixAs1-x does not seem to be influenced by the localized Bi levels. It is due to two factors. One is that the pressure dependence of the band gap energy is mainly determined by the D CBM of GaBixAs1-x. The D CBM of GaBixAs1-x is not influenced by the localized Bi levels. The other is that the small variation of the pressure coefficient for the D valence band maximum (VBM) state of GaBixAs1-x can be cancelled by the variation of the pressure coefficient for the D CBM state of GaBixAs1-x.

  6. Photoluminescence measurements of the 1,55 eV band of Ge doped Al sub(x)Ga sub(1-x)As

    International Nuclear Information System (INIS)

    Furtado, M.T.; Weid, J.P. von der.

    1984-01-01

    The photoluminescence of the 1,55 eV band of Ge doped Al sub(x)Ga sub(1-x)As, with x=0.30-0.33, grown by liquid phase epitaxy is presented. The broad shape was found to be due to a lattice relaxation upon optical transitions. Resonant modes with (h/2π)ω sub(q) approx. 35 + - 2 meV and (h/2π) ω sub(q) approx. 45 + - 2 meV are found for the optical band, yielding a zero phonon transition energy - 1.73 + - 0.02 eV and a Franck-Condon shift approx. 0.17-0.20 eV for the optical center. The activation energy of thermal quenching yields an associated donnor binding energy of 0.17 + - 0.04 eV. Possible mechanisms for the radiative transitions are discussed. (Author) [pt

  7. REVISITING THE FOSSIL GROUP CANDIDATES UGC 842 AND NGC 6034

    International Nuclear Information System (INIS)

    De Oliveira, R. Lopes; De Oliveira, C. Mendes; Bortoletto, D. R.; Cypriano, E.; Sodre, L.; Neto, G B. Lima; Carrasco, E. R.

    2010-01-01

    We present a new insight on NGC 6034 and UGC 842, two groups of galaxies previously reported in the literature as being fossil groups. The study is based on optical photometry and spectroscopy obtained with the CTIO Blanco telescope and Sloan Digital Sky Survey archival data. We find that NGC 6034 is embedded in a large structure, dominated by three rich clusters and other small groups. Its first and next four ranked galaxies have magnitude differences in the r band and projected distances which violate the optical criteria to classify it as a fossil group. We confirm that the UGC 842 group is a fossil group, but with about half the velocity dispersion that is reported in previous works. The velocity distribution of its galaxies reveals the existence of two structures in its line of sight, one with σ v ∼ 223 km s -1 and another with σ v ∼ 235 km s -1 , with a difference in velocity of ∼820 km s -1 . The main structure is dominated by passive galaxies, while these represent ∼60% of the second structure. The X-ray temperature for the intragroup medium of a group with such a velocity dispersion is expected to be kT ∼0.5-1 keV, against the observed value of kT ∼1.9 keV reported in the literature. This result makes UGC 842 a special case among fossil groups because (1) it represents more likely the interaction between two small groups, which warms the intragroup medium and/or (2) it could constitute evidence that member galaxies lost energy in the process of spiraling toward the group center, and decreased the velocity dispersion of the system. As far as we know, UGC 842 is the first low-mass fossil group studied in detail.

  8. RF phase focusing in portable x-band, linear accelerators

    International Nuclear Information System (INIS)

    Miller, R.H.; Deruyter, H.; Fowkes, W.R.; Potter, J.M.; Schonberg, R.G.; Weaver, J.N.

    1985-01-01

    In order to minimize the size and weight of the x-ray or neutron source for a series of portable radiographic linear accelerators, the x-ray head was packaged separately from the rest of the system and consists of only the linac accelerating structure, electron gun, built-in target, collimator, ion pump and an RF window. All the driving electronics and cooling are connected to the x-ray head through flexible waveguide, cables, and waterlines. The x-ray head has been kept small and light weight by using the RF fields for radial focusing, as well as for longitudinal bunching and accelerating the beam. Thus, no external, bulky magnetic focusing devices are required. The RF focusing is accomplished by alternating the sign of the phase difference between the RF and the beam and by tapering from cavity to cavity the magnitude of the buncher field levels. The former requires choosing the right phase velocity taper (mix of less than vp = c cavities) and the latter requires the right sizing of the cavity to cavity coupling smiles (irises)

  9. RF phase focusing in portable X-band, linear accelerators

    International Nuclear Information System (INIS)

    Miller, R.H.; Deruyter, H.; Fowkes, W.R.; Potter, J.W.; Schonberg, R.G.; Weaver, J.W.

    1985-01-01

    In order to minimize the size and weight of the x-ray or neutron source for a series of portable radiographic linear accelerators, the x-ray head was packaged separately from the rest of the system and consists of only the linac accelerating structure, electron gun, built-in target, collimator, ion pump and an RF window. All the driving electronics and cooling are connected to the x-ray head through flexible waveguide, cables, and waterlines. The x-ray head has been kept small and light weight by using the RF fields for radial focusing, as well as for longitudinal bunching and accelerating the beam. Thus, no external, bulky magnetic focusing devices are required. The RF focusing is accomplished by alternating the sign of the phase difference between the RF and the beam and by tapering from cavity to cavity the magnitude of the buncher field levels. The former requires choosing the right phase velocity taper (mix of less than vp=c cavities) and the latter requires the right sizing of the cavity to cavity coupling smiles (irises)

  10. Dynamics of Impurity and Valence Bands in Ga1-xMnxAs Within the Dynamical Mean-Field Approximation

    Energy Technology Data Exchange (ETDEWEB)

    Majidi, M. A. [University of Cincinnati; Moreno, Juana [University of North Dakota, Grand Forks; Jarrell, Mark [University of Cincinnati; Fishman, Randy Scott [ORNL; Aryanpour, K. A. [University of California, Davis

    2006-08-01

    We calculate the density-of-states and the spectral function of Ga1−xMnxAs within the dynamical mean-field approximation. Our model includes the competing effects of the strong spin-orbit coupling on the J=3/2 GaAs hole bands and the exchange interaction between the magnetic ions and the itinerant holes. We study the quasiparticle and impurity bands in the paramagnetic and ferromagnetic phases for different values of impurity-hole coupling Jc at a Mn doping of x=0.05. By analyzing the anisotropic angular distribution of the impurity band carriers at T=0, we conclude that the carrier polarization is optimal when the carriers move along the direction parallel to the average magnetization.

  11. Current state of X-band accelerating structure high gradient test. Be held at high energy accelerator organization on April 15, 2005

    International Nuclear Information System (INIS)

    Watanabe, Ken; Higo, Toshiyasu

    2005-01-01

    XTF (X-band Test Facility, Old name is GLCTA) is the high gradient test facility for X-band acceleration. We have installed an X-band 60cm structure (KX01) in the April 2004 and have been processing it for more than 10 months. Now it is under test on long-term operation. We report here the high gradient test result to date. (author)

  12. Controllable group velocity of the probe light in a Λ-type system with two fold levels

    International Nuclear Information System (INIS)

    Jin Lihui; Gong Shangqing; Niu Yueping; Li Ruxin; Jin Shiqi

    2006-01-01

    The group velocities of the probe laser field are studied in a Λ-type system where one lower state has two fold levels coupled by a control field. It is found that the interaction of double dark states leads to controllable group velocity of the probe field in this system. It can be easily realized, due to the interacting double dark resonances, that one of the group velocities at transparency positions is much slower than the other by tuning the control field to be off resonance. In particular, when the control field is on resonance, we can obtain two equal slow group velocities with a broader EIT width, which provides potential applications in quantum storage and retrieval of light

  13. Air velocity profiles near sleeve blockages in an unheated 7 x 7 rod bundle. [PWR

    Energy Technology Data Exchange (ETDEWEB)

    Creer, J. M.; Bates, J. M.

    1979-04-01

    Local air velocity measurements were obtained with a laser Doppler anemometer near flow blockages in an unheated 7 x 7 rod bundle. Sleeve blockages were positioned on the center nine rods to create an area reduction of 90% in the center four subchannels of the bundle. Experimental results indicated that severe flow disturbances occurred downstream from the blockage cluster but showed only minor flow disturbances upstream from the blockage. Flow reversals were detected downstream from the blockage and persisted for approximately five subchannel hydraulic diameters. The air velocity profiles were in excellent agreement with water velocity data previously obtained at essentially the same Reynolds number. Subchannel average velocity predictions obtained with the COBRA computer program were in good agreement with subchannel average velocities estimated using the measured local velocity data.

  14. Synchrotron X-ray PIV Technique for Measurement of Blood Flow Velocity

    International Nuclear Information System (INIS)

    Kim, Guk Bae; Lee, Sang Joon; Je, Jung Ho

    2007-01-01

    Synchrotron X-ray micro-imaging method has been used to observe internal structures of various organisms, industrial devices, and so on. However, it is not suitable to see internal flows inside a structure because tracers typically employed in conventional optical flow visualization methods cannot be detectable with the X-ray micro-imaging method. On the other hand, a PIV (particle image velocimetry) method which has recently been accepted as a reliable quantitative flow visualization technique can extract lots of flow information by applying digital image processing techniques However, it is not applicable to opaque fluids such as blood. In this study, we combined the PIV method and the synchrotron X-ray micro-imaging technique to compose a new X-ray PIV technique. Using the X-ray PIV technique, we investigated the optical characteristics of blood for a coherent synchrotron X-ray beam and quantitatively visualized real blood flows inside an opaque tube without any contrast media. The velocity field information acquired would be helpful for investigating hemorheologic characteristics of the blood flow

  15. Development and studies of Cd_1_−_xMg_xTe thin films with varying band gaps to understand the Mg incorporation and the related material properties

    International Nuclear Information System (INIS)

    Palomera, Roger C.; Martínez, Omar S.; Pantoja-Enriquez, J.; Mathews, N.R.; Reyes-Banda, Martín G.; Krishnan, B.; Mathew, X.

    2017-01-01

    Highlights: • Cd_1_−_xMg_xTe films with band gap in the range 1.47–2.41 eV is obtained. • Cd substitution by Mg was confirmed with SIMS and XPS analysis. • Cd_1_−_xMg_xTe films maintained CdTe structural features but with higher band gap. • Mg incorporation in CdTe inhibited grain growth. - Abstract: In this paper we report a systematic work involving the development of Cd_1_−_xMg_xTe thin films by co-evaporation of CdTe and Mg. The evaporation rate of both materials were adjusted to obtain ternary films of varying stoichiometry and hence the band gap. We have deposited films with band gap ranging from 1.47 to 2.41 eV. The films were characterized for structural, morphological, optical, opto-electronic, and spectroscopic properties. The film stoichiometry was studied across the thickness using SIMS data. SEM images showed that the grain size has a dependence on Mg content in the film, which inhibits the grain growth. The structural parameters showed a systematic dependence on Mg content in the film, however, there was no noticeable change in the XRD reflections with respect that of pure CdTe for lower concentrations of Mg. XPS analysis shed light on the incorporation of Mg further supporting the band gap variations observed with the UV–Vis spectroscopic studies. The photoresponse of the film was affected by Mg incorporation. Prototype devices of the type Cd_1_−_XMg_xTe/CdS were fabricated and the results are discussed.

  16. A triboelectric closed loop band system for the generation of x-rays

    Science.gov (United States)

    Van Cleve, E.; Lucas, B.; Ganlieli, Z.; Wong, E. W.; Cortes, P.; Mehta, N.; Cuadra, D.; Fong, J.; Hansen, S.; Kotowski, A.; Camara, C. G.

    2015-08-01

    X-ray have been commercially produced using the same basic design since their discovery by Wilhelm Roentgen in 1895, for which he was awarded the first Nobel prize in physics. This technology requires high voltage elements, ultra high vacuum tubes, and high voltage electronics. The vacuum and high voltage drive up the price of x-ray technology and in order to bring down the cost, a brand new way to produce x-rays is needed. In 2008 Carlos Camara, Juan Escobar, Jonathan R. Hird, and Seth Putterman1 discovered that by pealing scotch tape in a vacuum you could create enough x-rays to take an x-ray radiograph of a finger. This lead to the formation of Tribogenics and the development of the rod and band x-ray architecture.

  17. Type II band alignment in Ge1-x-ySixSny/Ge1-α-βSiαSnβ heterojunctions

    Science.gov (United States)

    Dey, Swagata; Mukhopadhyay, Bratati; Sen, Gopa; Basu, P. K.

    2018-02-01

    We have examined type II band alignment in Ge1-x-ySixSny/Ge1-α-βSiαSβ heterojunctions grown on virtual substrates in Si platform. It is found that, for different values of x, y, α and β, direct band gap type II band line up can be achieved for both tensile and compressive strains. The calculated band gap energy corresponds to the mid infrared to far infrared regions in the electromagnetic spectrum.

  18. Energy-band alignment of (HfO2)x(Al2O3)1-x gate dielectrics deposited by atomic layer deposition on β-Ga2O3 (-201)

    Science.gov (United States)

    Yuan, Lei; Zhang, Hongpeng; Jia, Renxu; Guo, Lixin; Zhang, Yimen; Zhang, Yuming

    2018-03-01

    Energy band alignments between series band of Al-rich high-k materials (HfO2)x(Al2O3)1-x and β-Ga2O3 are investigated using X-Ray Photoelectron Spectroscopy (XPS). The results exhibit sufficient conduction band offsets (1.42-1.53 eV) in (HfO2)x(Al2O3)1-x/β-Ga2O3. In addition, it is also obtained that the value of Eg, △Ec, and △Ev for (HfO2)x(Al2O3)1-x/β-Ga2O3 change linearly with x, which can be expressed by 6.98-1.27x, 1.65-0.56x, and 0.48-0.70x, respectively. The higher dielectric constant and higher effective breakdown electric field of (HfO2)x(Al2O3)1-x compared with Al2O3, coupled with sufficient barrier height and lower gate leakage makes it a potential dielectric for high voltage β-Ga2O3 power MOSFET, and also provokes interest in further investigation of HfAlO/β-Ga2O3 interface properties.

  19. Solid-state pulse modulator for a 1.7-MW X-band magnetron

    International Nuclear Information System (INIS)

    Choi, Jaegu; Shin, Yongmoon; Choi, Youngwook; Kim, Kwanho

    2014-01-01

    Medical linear accelerators (LINAC) for cancer treatment require pulse modulators to generate high-power pulses with a fast rise time, flat top and short duration to drive high-power magnetrons. Solid-state pulse modulators (SSPM) for medical LINACs that use high power semiconductor switches with high repetition rates, high stability and long lifetimes have been introduced to replace conventional linear-type pulse generators that use gaseous discharge switches. In this paper, the performance of a developed SSPM, which mainly consists of a capacitor charger, an insulated-gate bipolar transistor (IGBT) - capacitor stack and a pulse transformer, is evaluated with a dummy load and an X-band magnetron load. A theoretical analysis of the pulse transformer, which is a critical element of the SSPM, is carried out. The output pulse has a fast rise time and low droop, such that the modulator can drive the X-band magnetron.

  20. Spin splitting in band structures of BiTeX (X=Cl, Br, I) monolayers

    Science.gov (United States)

    Hvazdouski, D. C.; Baranava, M. S.; Stempitsky, V. R.

    2018-04-01

    In systems with breaking of inversion symmetry a perpendicular electric field arises that interacts with the conduction electrons. It may give rise to electron state splitting even without influence of external magnetic field due to the spin-orbital interaction (SOI). Such a removal of the spin degeneracy is called the Rashba effect. Nanostructure with the Rashba effect can be part of a spin transistor. Spin degeneracy can be realized in a channel from a material of this type without additive of magnetic ions. Lack of additive increases the charge carrier mobility and reliability of the device. Ab initio simulations of BiTeX (X=Cl, Br, I) monolayers have been carried out using VASP wherein implemented DFT method. The study of this structures is of interest because such sort of structures can be used their as spin-orbitronics materials. The crystal parameters of BiTeCl, BiTeBr, BiTeI have been determined by the ionic relaxation and static calculations. It is necessary to note that splitting of energy bands occurs in case of SOI included. The values of the Rashba coefficient aR (in the range from 6.25 to 10.00 eV·Å) have high magnitudes for spintronics materials. Band structure of monolayers structures have ideal Rashba electron gas, i.e. there no other energy states near to Fermi level except Rashba states.

  1. High power X-band coaxial amplifier experiments

    International Nuclear Information System (INIS)

    Davis, T.J.; Nation, J.A.

    1991-01-01

    Studies are continuing on the development of X-band coaxial microwave amplifiers as a source for next generation linear colliders. Coaxial amplifiers employ an annular electron beam propagating between inner and outer drift tube conductors, a configuration which allows large increases in beam current over standard pencil beam amplifiers. Large average diameter systems may still be used without mode competition since TM mode cutoff frequencies are controlled by the separation between conductors. A number of amplifier configurations are being studied, all primed by a driven initial cavity which resonates around 9 GHz. Simple theory of coaxial systems and particle-in-cell simulations are presented, as well as initial experimental results using a 420 keV, 7-8 kA, 9 cm diameter annular beam

  2. TlHgInS 3 : An Indirect-Band-Gap Semiconductor with X-ray Photoconductivity Response

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hao; Malliakas, Christos D.; Han, Fei; Chung, Duck Young; Kanatzidis, Mercouri G.

    2015-08-11

    The quaternary compound TlHgInS3 crystallizes in a new structure type of space group, C2/c, with cell parameters a = 13.916(3) angstrom, b = 3.9132(8) angstrom, c = 21.403(4) angstrom, beta = 104.16(3)degrees, V = 1130.1(8) angstrom(3), and rho = 7.241 g/cm(3). The structure is a unique three-dimensional framework with parallel tunnels, which is formed by (1)(infinity)[InS33-] infinite chains bridged by linearly coordinated Hg2+ ions. TlHgInS3 is a semiconductor with a band gap of 1.74 eV and a resistivity of similar to 4.32 G Omega cm. TlHgInS3 single crystals exhibit photocurrent response when exposed to Ag X-rays. The mobility-lifetime product (mu tau) of the electrons and holes estimated from the photocurrent measurements are (mu tau)(e) approximate to 3.6 x 10(-4) cm(2)/V and (mu tau)(h) approximate to 2.0 x 10(-4) cm(2)/V. Electronic structure calculations at the density functional theory level indicate an indirect band gap and a relatively small effective mass for both electrons and holes. Based on the photoconductivity data, TlHgInS3 is a potential material for radiation detection applications.

  3. 7 CFR 29.1165 - Lugs (X Group).

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Lugs (X Group). 29.1165 Section 29.1165 Agriculture... INSPECTION Standards Grades § 29.1165 Lugs (X Group). This group consists of leaves normally grown near the bottom of the stalk. Leaves of the X group usually have a blunt tip and open face; they show some ground...

  4. Dynamics of Impurity and Valence Bands in Ga1-xMnxAs Within the Dynamical Mean-Field Approximation

    International Nuclear Information System (INIS)

    Majidi, M.A.; Moreno, Juana; Jarrell, Mark; Fishman, Randy Scott; Aryanpour, K.A.

    2006-01-01

    We calculate the density-of-states and the spectral function of Ga 1-x Mn x As within the dynamical mean-field approximation. Our model includes the competing effects of the strong spin-orbit coupling on the J=3/2 GaAs hole bands and the exchange interaction between the magnetic ions and the itinerant holes. We study the quasiparticle and impurity bands in the paramagnetic and ferromagnetic phases for different values of impurity-hole coupling J c at a Mn doping of x=0.05. By analyzing the anisotropic angular distribution of the impurity band carriers at T=0, we conclude that the carrier polarization is optimal when the carriers move along the direction parallel to the average magnetization.

  5. Spin excitation and band-narrowing in AlxGa1-xAs heterostructures

    International Nuclear Information System (INIS)

    Miah, M. Idrish

    2010-01-01

    We studied the spin excitation in dependences of the applied electric field and lattice temperature (LT) via the measurements of the circularly polarized photoluminescence (CPPL) in Al x Ga 1-x As heterostructures (HSs). The intensity of CPPL was found to strongly depend on the electric field applied to the HSs. The CPPL was also found to enhance with decreasing LT. It was demonstrated that the observed LT dependence might be due to the LT-dependent band-gap shift of the HS materials.

  6. Valence and conduction band offsets at low-k a-SiO{sub x}C{sub y}:H/a-SiC{sub x}N{sub y}:H interfaces

    Energy Technology Data Exchange (ETDEWEB)

    King, Sean W., E-mail: sean.king@intel.com; Brockman, Justin; French, Marc; Jaehnig, Milt; Kuhn, Markus [Logic Technology Development, Intel Corporation, Hillsboro, Oregon 97124 (United States); French, Benjamin [Ocotillo Materials Laboratory, Intel Corporation, Chandler, Arizona 85248 (United States)

    2014-09-21

    In order to understand the fundamental electrical leakage and reliability failure mechanisms in nano-electronic low-k dielectric/metal interconnect structures, we have utilized x-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy to determine the valence and conduction band offsets present at interfaces between non-porous and porous low-k a-SiO{sub x}C{sub y}:H interlayer dielectrics and a-SiC{sub x}N{sub y}:H metal capping layers. The valence band offset for such interfaces was determined to be 2.7±0.2 eV and weakly dependent on the a-SiOC:H porosity. The corresponding conduction band offset was determined to be 2.1±0.2 eV. The large band offsets indicate that intra metal layer leakage is likely dominated by defects and trap states in the a-SiOC:H and a-SiCN:H dielectrics.

  7. Velocity-resolved [Ne III] from X-ray irradiated Sz 102 microjets

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chun-Fan; Shang, Hsien [Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA), P.O. Box 23-141, Taipei 10641, Taiwan (China); Walter, Frederick M. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States); Herczeg, Gregory J. [The Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)

    2014-05-10

    Neon emission lines are good indicators of high-excitation regions close to a young stellar system because of their high ionization potentials and large critical densities. We have discovered [Ne III] λ3869 emission from the microjets of Sz 102, a low-mass young star in Lupus III. Spectroastrometric analyses of two-dimensional [Ne III] spectra obtained from archival high-dispersion (R ≈ 33, 000) Very Large Telescope/UVES data suggest that the emission consists of two velocity components spatially separated by ∼0.''3, or a projected distance of ∼60 AU. The stronger redshifted component is centered at ∼ + 21 km s{sup –1} with a line width of ∼140 km s{sup –1}, and the weaker blueshifted component at ∼ – 90 km s{sup –1} with a line width of ∼190 km s{sup –1}. The two components trace velocity centroids of the known microjets and show large line widths that extend across the systemic velocity, suggesting their potential origins in wide-angle winds that may eventually collimate into jets. Optical line ratios indicate that the microjets are hot (T ≲ 1.6 × 10{sup 4} K) and ionized (n{sub e} ≳ 5.7 × 10{sup 4} cm{sup –3}). The blueshifted component has ∼13% higher temperature and ∼46% higher electron density than the redshifted counterpart, forming a system of an asymmetric pair of jets. The detection of the [Ne III] λ3869 line with the distinct velocity profile suggests that the emission originates in flows that may have been strongly ionized by deeply embedded hard X-ray sources, most likely generated by magnetic processes. The discovery of [Ne III] λ3869 emission along with other optical forbidden lines from Sz 102 supports the picture of wide-angle winds surrounding magnetic loops in the close vicinity of the young star. Future high-sensitivity X-ray imaging and high angular-resolution optical spectroscopy may help confirm the picture proposed.

  8. Velocity-resolved [Ne III] from X-ray irradiated Sz 102 microjets

    International Nuclear Information System (INIS)

    Liu, Chun-Fan; Shang, Hsien; Walter, Frederick M.; Herczeg, Gregory J.

    2014-01-01

    Neon emission lines are good indicators of high-excitation regions close to a young stellar system because of their high ionization potentials and large critical densities. We have discovered [Ne III] λ3869 emission from the microjets of Sz 102, a low-mass young star in Lupus III. Spectroastrometric analyses of two-dimensional [Ne III] spectra obtained from archival high-dispersion (R ≈ 33, 000) Very Large Telescope/UVES data suggest that the emission consists of two velocity components spatially separated by ∼0.''3, or a projected distance of ∼60 AU. The stronger redshifted component is centered at ∼ + 21 km s –1 with a line width of ∼140 km s –1 , and the weaker blueshifted component at ∼ – 90 km s –1 with a line width of ∼190 km s –1 . The two components trace velocity centroids of the known microjets and show large line widths that extend across the systemic velocity, suggesting their potential origins in wide-angle winds that may eventually collimate into jets. Optical line ratios indicate that the microjets are hot (T ≲ 1.6 × 10 4 K) and ionized (n e ≳ 5.7 × 10 4 cm –3 ). The blueshifted component has ∼13% higher temperature and ∼46% higher electron density than the redshifted counterpart, forming a system of an asymmetric pair of jets. The detection of the [Ne III] λ3869 line with the distinct velocity profile suggests that the emission originates in flows that may have been strongly ionized by deeply embedded hard X-ray sources, most likely generated by magnetic processes. The discovery of [Ne III] λ3869 emission along with other optical forbidden lines from Sz 102 supports the picture of wide-angle winds surrounding magnetic loops in the close vicinity of the young star. Future high-sensitivity X-ray imaging and high angular-resolution optical spectroscopy may help confirm the picture proposed.

  9. BiOCl{sub x}Br{sub y}I{sub z} (x + y + z = 1) solid solutions with controllable band gap and highly enhanced visible light photocatalytic performances

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xiuguo; Zhang, Yangyang; Li, Chunmei; Zhang, Zhifeng; Peng, Zheng; Si, Huayan; Zhang, Jianmin [School of Materials Science and Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043 (China); Li, Yanting, E-mail: yantingcn@stdu.edu.cn [School of Materials Science and Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043 (China); Hebei Provincial Key Laboratory of Traffic Engineering materials, Shijiazhuang Tiedao University, Shijiazhuang 050043 (China)

    2015-07-25

    Highlights: • BiOCl{sub x}Br{sub y}I{sub z} solid solutions were prepared by hydrolysis method. • Band gap of the solid solutions can be controllable by adjusting the molar ratio of halogen ions. • The samples show higher visible light photocatalytic activity than pure BiOX. • Orbital diversification of VB is beneficial to separating the holes and electrons effectively. • The mechanisms are discussed by active species trapping and band theory. - Abstract: A series of BiOCl{sub x}Br{sub y}I{sub z} solid solutions with controllable band gap and highly enhanced visible light photocatalytic performances were synthesized by a simple hydrolysis method. The samples were characterized by X-ray powder diffraction, UV–vis diffuse reflectance spectra, scanning electron microscope, high-resolution transmission electron microscopy and Brunauer–Emmett–Teller analysis. By adjusting the molar ratio of halogen ions, the band gap of BiOCl{sub x}Br{sub y}I{sub z} could be controllable to the suitable value for a photocatalytic reaction. Especially, BiOCl{sub x}Br{sub y}I{sub z} with a 1:1:2 molar ratio of Cl, Br to I showed the highest visible light photocatalytic activity for the degradation of methyl orange than individual BiOX systems. The degradation efficiency could reach over 90% within 60 min. The possible mechanism of photogenerated carrier transfer and higher photocatalytic activity was analyzed by active species trapping and energy band theory.

  10. Band gap and mobility of epitaxial perovskite BaSn1 -xHfxO3 thin films

    Science.gov (United States)

    Shin, Juyeon; Lim, Jinyoung; Ha, Taewoo; Kim, Young Mo; Park, Chulkwon; Yu, Jaejun; Kim, Jae Hoon; Char, Kookrin

    2018-02-01

    A wide band-gap perovskite oxide BaSn O3 is attracting much attention due to its high electron mobility and oxygen stability. On the other hand, BaHf O3 was recently reported to be an effective high-k gate oxide. Here, we investigate the band gap and mobility of solid solutions of BaS n1 -xH fxO3 (x =0 -1 ) (BSHO) as a basis to build advanced perovskite oxide heterostructures. All the films were epitaxially grown on MgO substrates using pulsed laser deposition. Density functional theory calculations confirmed that Hf substitution does not create midgap states while increasing the band gap. From x-ray diffraction and optical transmittance measurements, the lattice constants and the band-gap values are significantly modified by Hf substitution. We also measured the transport properties of n -type La-doped BSHO films [(Ba ,La ) (Sn ,Hf ) O3 ] , investigating the feasibility of modulation doping in the BaSn O3/BSHO heterostructures. The Hall measurement data revealed that, as the Hf content increases, the activation rate of the La dopant decreases and the scattering rate of the electrons sharply increases. These properties of BSHO films may be useful for applications in various heterostructures based on the BaSn O3 system.

  11. Group velocity measurement from the propagation of the ionization front in a surface-wave-produced plasma

    International Nuclear Information System (INIS)

    Cotrino, J.; Gamero, A.; Sola, A.; Lao, C.

    1989-01-01

    During the first instant, previous to steady-state in a surface-wave-produced plasma, an ionization front advance front the launcher to the plasma column end. The velocity of the ionization front is much slower than the group velocity of the surface wave, this give a reflection of the incident signal on the moving ionization front. In this paper, the authors use this effect to calculate the surface wave group velocity

  12. Determination of group velocity of propagation of Lamb waves in aluminium plate using piezoelectric transducers

    Directory of Open Access Journals (Sweden)

    Lašová Z.

    2017-06-01

    Full Text Available A prior knowledge of group velocities of Lamb wave modes is a key for analysis of time signals in guidedwave based structural health monitoring. The identification of multiple wave modes may be complicated due to dependency of group velocity on frequency (dispersion. These dependencies for infinite plate of constant thickness can be calculated by a numerical solution of analytic equation. Two alternative approaches to determine group velocities of zero-order Lamb wave modes in aluminum plate were used in this work: Two-dimensional Fast Fourier Transform (2D-FFT and methods of time-frequency processing. 2D-FFT requires a high number of time signals in equidistant points, therefore it was applied on data from finite element analysis of wave propagation in the plate. Group velocities for chosen frequencies were also determined using wavelet transform (WT of signals as differencies of times of arrival measured by a pair of piezoelectric transducers. The results from 2D-FFT and wavelet transform were compared to the analytic solution.

  13. Band structure of TiO sub 2 -doped yttria-stabilized zirconia probed by soft-x-ray spectroscopy

    CERN Document Server

    Higuchi, T; Kobayashi, K; Yamaguchi, S; Fukushima, A; Shin, S

    2003-01-01

    The electronic structure of TiO sub 2 -doped yttria-stabilized zirconia (YSZ) has been studied by soft-X-ray emission spectroscopy (SXES) and X-ray absorption spectroscopy (XAS). The valence band is mainly composed of the O 2p state. The O 1s XAS spectrum exhibits the existence of the Ti 3d unoccupied state under the Zr 4d conduction band. The intensity of the Ti 3d unoccupied state increases with increasing TiO sub 2 concentration. The energy separation between the top of the valence band and the bottom of the Ti 3d unoccupied state is in accord with the energy gap, as expected from dc-polarization and total conductivity measurements. (author)

  14. Optical Observations of M81 Galaxy Group in Narrow Band [SII] and H_alpha Filters: Holmberg IX

    Directory of Open Access Journals (Sweden)

    Arbutina, B.

    2009-12-01

    Full Text Available We present observations of the nearby tidal dwarf galaxy Holmberg IX in M81 galaxy group in narrow band [SII] and H$alpha$ filters, carried out in March and November 2008 with the 2m RCC telescope at NAO Rozhen, Bulgaria. Our search for resident supernova remnants (identified as sources with enhanced [SII] emission relative to their H$alpha$ emission in this galaxy yielded no sources of this kind, besides M&H 10-11 or HoIX X-1. Nevertheless, we found a number of objects with significant H$alpha$ emission that probably represent uncatalogued HII regions.

  15. Band gap and band offset of (GaIn)(PSb) lattice matched to InP

    Science.gov (United States)

    Köhler, F.; Böhm, G.; Meyer, R.; Amann, M.-C.

    2005-07-01

    Metastable (GaxIn1-x)(PySb1-y) layers were grown on (001) InP substrates by gas source molecular beam epitaxy. Low-temperature photoluminescence spectroscopy was applied to these heterostructures and revealed spatially indirect band-to-band recombination of electrons localized in the InP with holes in the (GaxIn1-x)(PySb1-y). In addition, samples with layer thicknesses larger than 100nm showed direct PL across the band gap of (GaxIn1-x)(PySb1-y). Band-gap energies and band offset energies of (GaxIn1-x)(PySb1-y) relative to InP were derived from these PL data. A strong bowing parameter was observed.

  16. Compositional dependence of the band-gap of Ge{sub 1−x−y}Si{sub x}Sn{sub y} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wendav, Torsten, E-mail: wendav@physik.hu-berlin.de [AG Theoretische Optik & Photonik, Humboldt Universität zu Berlin, Newtonstr. 15, 12489 Berlin (Germany); Fischer, Inga A.; Oehme, Michael; Schulze, Jörg [Institut für Halbleitertechnik, Universität Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart (Germany); Montanari, Michele; Zoellner, Marvin Hartwig; Klesse, Wolfgang [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Capellini, Giovanni [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Dipartimento di Scienze, Università Roma Tre, Viale Marconi 446, 00146 Roma (Italy); Driesch, Nils von den; Buca, Dan [Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies, Forschungszentrum Jülich, 52428 Jülich (Germany); Busch, Kurt [AG Theoretische Optik & Photonik, Humboldt Universität zu Berlin, Newtonstr. 15, 12489 Berlin (Germany); Max-Born-Institut, Max-Born-Str. 2 A, 12489 Berlin (Germany)

    2016-06-13

    The group-IV semiconductor alloy Ge{sub 1−x−y}Si{sub x}Sn{sub y} has recently attracted great interest due to its prospective potential for use in optoelectronics, electronics, and photovoltaics. Here, we investigate molecular beam epitaxy grown Ge{sub 1−x−y}Si{sub x}Sn{sub y} alloys lattice-matched to Ge with large Si and Sn concentrations of up to 42% and 10%, respectively. The samples were characterized in detail by Rutherford backscattering/channeling spectroscopy for composition and crystal quality, x-ray diffraction for strain determination, and photoluminescence spectroscopy for the assessment of band-gap energies. Moreover, the experimentally extracted material parameters were used to determine the SiSn bowing and to make predictions about the optical transition energy.

  17. Pulse modulator for X-band klystron at GLCTA

    International Nuclear Information System (INIS)

    Akemoto, M.; Honma, H.; Nakajima, H.; Shidara, T.; Fukuda, S.

    2004-01-01

    This paper presents an X-band klystron modulator recently constructed for the Global Linear Collider Test Accelerator (GLCTA) at KEK. The modulator is a thyratron-switched line-type design, and operates two klystrons up to 75 MW peak power, 1.6 μs rf pulse width and up to 150 Hz repetition rate. The major goals of the modulator are reasonably compact size and high reliability. One notable feature is the use of eight 30kJ/s switching power supplies in parallel to charge the pulse forming network. These supplies are a major contributor to compact size of the modulator. The design, specifications and results of performance tests of the modulator are described. (author)

  18. Measurements of higher order modes in a 30 cm long X-band structure

    International Nuclear Information System (INIS)

    Xiao, L.; Liang, Y.; Tong, D.; Zhang, H.

    2001-01-01

    The use of a cage of metallic wires as a bead is proposed to measure the higher order modes (HOMs) in an X-band accelerating structure. These long thin wires can isolate the longitudinal electric field component from other field components and produce sufficient frequency shift in bead-pull measurements. In the setup described in this paper, the bead is made by sputtering silver film onto a thin nylon line through a specially designed fixture. The cage has a size of approximately 0.5 mm in diameter, 2 mm in length and more than six metallic wires of less than 0.1 mm in width. The fabrication and calibration of the cage are described. The longitudinal electric fields of the lowest passband dipole mode TM 110 in a 30 cm long X-band structure are measured by bead-pull measurements. Results are compared with the calculated ones obtained from URMELT-code

  19. Theoretical band structure of the superconducting antiperovskite oxide Sr3-xSnO

    Science.gov (United States)

    Ikeda, Atsutoshi; Fukumoto, Toshiyuki; Oudah, Mohamed; Hausmann, Jan Niklas; Yonezawa, Shingo; Kobayashi, Shingo; Sato, Masatoshi; Tassel, Cédric; Takeiri, Fumitaka; Takatsu, Hiroshi; Kageyama, Hiroshi; Maeno, Yoshiteru

    2018-05-01

    In order to investigate the position of the strontium deficiency in superconductive Sr3-xSnO, we synthesized and measured X-ray-diffraction patterns of Sr3-xSnO (x ∼ 0.5). Because no clear peaks originating from superstructures were observed, strontium deficiency is most likely to be randomly distributed. We also performed first-principles band-structure calculations on Sr3-xSnO (x = 0, 0.5) using two methods: full-potential linearized-augmented plane-wave plus local orbitals method and the Korringa-Kohn-Rostoker Green function method combined with the coherent potential approximation. We revealed that the Fermi energy of Sr3-xSnO in case of x ∼ 0.5 is about 0.8 eV below the original Fermi energy of the stoichiometric Sr3SnO, where the mixing of the valence p and conduction d orbitals are considered to be small.

  20. Seasonal and inter-annual variability in velocity and frontal position of Siachen Glacier (Eastern Karakorum) using multi-satellite data

    Science.gov (United States)

    Usman, M.; Furuya, M.; Sakakibara, D.; Abe, T.

    2017-12-01

    The anomalous behavior of Karakorum glaciers is a hot topic of discussion in the scientific community. Siachen Glacier is one of the longest glaciers ( 75km) in Karakorum Range. This glacier is supposed to be a surge type but so far no studies have confirmed this claim. Detailed velocity mapping of this glacier can possibly provide some clues about intra/inter-annual changes in velocity and observed terminus. Using L-band SAR data of ALOS-1/2, we applied the feature tracking technique (search patch of 128x128 pixels (range x azimuth) , sampling interval of 12x36 pixels) to derive velocity changes; we used GAMMA software. The velocity was calculated by following the parallel flow assumption. To calculate the local topographic gradient unit vector, we used ASTER-GDEM. We also used optical images acquired by Landsat 5 Thematic Mapper (TM), the Landsat 7 Enhanced Thematic Mapper Plus (ETM+) to derive surface velocity. The algorithm we used is Cross-Correlation in Frequency domain on Orientation images (CCF-O). The velocity was finally calculated by setting a flow line and averaging over the area of 200x200m2. The results indicate seasonal speed up signals that modulate inter-annually from 1999 to 2011, with slight or no change in the observed frontal position. However, in ALOS-2 data, the `observed terminus' seems to have been advancing.

  1. Offshore Rayleigh Group Velocity Observations of the South Island, New Zealand, from Ambient Noise Data

    KAUST Repository

    Yeck, William L.; Sheehan, Anne F.; Stachnik, Joshua C.; Lin, Fan-Chi

    2017-01-01

    We present azimuthally anisotropic Rayleigh group velocity models from 8 - 35 s both offshore and onshore of the South Island of New Zealand. We use MOANA (Marine Observations of Anisotropy Near Aotearoa) broadband ocean seismic data in combination with on land data from the New Zealand National Seismography Network (NZNSN) to investigate the seismic structure of the flanks of the Australian-Pacific plate boundary. At 8 s, we observe low offshore group velocities best explained by the influence of the water layer and thick water-laden sediments. At long periods (20-30 s), group velocities are lower on the South Island relative to its offshore flanks, due to thickened crust beneath the island, with the lowest velocities primarily beneath the Southern Alps. Group velocity azimuthal anisotropy fast directions near the Alpine Fault align with the direction of relative plate motion between the Australian and Pacific plates. In the southern portion of the island, fast directions rotate anticlockwise, likely in response to a decrease in dextral shearing away from the plate boundary. Azimuthal anisotropy fast directions align with absolute plate motion offshore on the Pacific plate. Based on the depth sensitivity of our observations, we suggest diffuse deformation occurs throughout the crust. Our observations match trends in previous Pn anisotropy and SKS shear wave splitting observations, and therefore suggest a consistent pattern of distributed deformation throughout the lithosphere.

  2. Offshore Rayleigh Group Velocity Observations of the South Island, New Zealand, from Ambient Noise Data

    KAUST Repository

    Yeck, William L.

    2017-02-15

    We present azimuthally anisotropic Rayleigh group velocity models from 8 - 35 s both offshore and onshore of the South Island of New Zealand. We use MOANA (Marine Observations of Anisotropy Near Aotearoa) broadband ocean seismic data in combination with on land data from the New Zealand National Seismography Network (NZNSN) to investigate the seismic structure of the flanks of the Australian-Pacific plate boundary. At 8 s, we observe low offshore group velocities best explained by the influence of the water layer and thick water-laden sediments. At long periods (20-30 s), group velocities are lower on the South Island relative to its offshore flanks, due to thickened crust beneath the island, with the lowest velocities primarily beneath the Southern Alps. Group velocity azimuthal anisotropy fast directions near the Alpine Fault align with the direction of relative plate motion between the Australian and Pacific plates. In the southern portion of the island, fast directions rotate anticlockwise, likely in response to a decrease in dextral shearing away from the plate boundary. Azimuthal anisotropy fast directions align with absolute plate motion offshore on the Pacific plate. Based on the depth sensitivity of our observations, we suggest diffuse deformation occurs throughout the crust. Our observations match trends in previous Pn anisotropy and SKS shear wave splitting observations, and therefore suggest a consistent pattern of distributed deformation throughout the lithosphere.

  3. Chromosome Banding in Amphibia. XXXII. The Genus Xenopus (Anura, Pipidae).

    Science.gov (United States)

    Schmid, Michael; Steinlein, Claus

    2015-01-01

    Mitotic chromosomes of 16 species of the frog genus Xenopus were prepared from kidney and lung cell cultures. In the chromosomes of 7 species, high-resolution replication banding patterns could be induced by treating the cultures with 5-bromodeoxyuridine (BrdU) and deoxythymidine (dT) in succession, and in 6 of these species the BrdU/dT-banded chromosomes could be arranged into karyotypes. In the 3 species of the clade with 2n = 20 and 4n = 40 chromosomes (X. tropicalis, X. epitropicalis, X. new tetraploid 1), as well as in the 3 species with 4n = 36 chromosomes (X. laevis, X. borealis, X. muelleri), the BrdU/dT-banded karyotypes show a high degree of homoeology, though differences were detected between these groups. Translocations, inversions, insertions or sex-specific replication bands were not observed. Minor replication asynchronies found between chromosomes probably involve heterochromatic regions. BrdU/dT replication banding of Xenopus chromosomes provides the landmarks necessary for the exact physical mapping of genes and repetitive sequences. FISH with an X. laevis 5S rDNA probe detected multiple hybridization sites at or near the long-arm telomeric regions in most chromosomes of X. laevis and X. borealis, whereas in X. muelleri, the 5S rDNA sequences are located exclusively at the long-arm telomeres of a single chromosome pair. Staining with the AT base pair-specific fluorochrome quinacrine mustard revealed brightly fluorescing heterochromatic regions in the majority of X. borealis chromosomes which are absent in other Xenopus species.

  4. Evaluation of the JPL X-band 32 element active array. [for deep space communication

    Science.gov (United States)

    Boreham, J. F.; Postal, R. B.; Conroy, B. L.

    1979-01-01

    Tests performed on an X-band 32-element active array are described. Antenna pattern characteristics of the array were tested in its standard operating mode as well as several degraded performance modes, including failures of 1, 2, 3, 4, 8, 16, and 31 elements. Additionally, the array was characterized with the addition of a metallic shroud, and also characterized versus rf drive level and at a single off-axis electronic beamsteered position. Characterization was performed on several of the 3/4-watt, three-stage, X-band solid-state power amplifier modules. The characterization included swept amplitude response, amplitude and phase versus temperature from -20 to +60 C, and intermodulation distortion of selected modules. The array is described and conclusions and recommendations based upon the experience and results achieved are included.

  5. The Cryogenic AntiCoincidence detector for ATHENA X-IFU: a scientific assessment of the observational capabilities in the hard X-ray band

    Science.gov (United States)

    D'Andrea, M.; Lotti, S.; Macculi, C.; Piro, L.; Argan, A.; Gatti, F.

    2017-12-01

    ATHENA is a large X-ray observatory, planned to be launched by ESA in 2028 towards an L2 orbit. One of the two instruments of the payload is the X-IFU: a cryogenic spectrometer based on a large array of TES microcalorimeters, able to perform integral field spectrography in the 0.2-12 keV band (2.5 eV FWHM at 6 keV). The X-IFU sensitivity is highly degraded by the particle background expected in the L2 orbit, which is induced by primary protons of both galactic and solar origin, and mostly by secondary electrons. To reduce the particle background level and enable the mission science goals, the instrument incorporates a Cryogenic AntiCoincidence detector (CryoAC). It is a 4 pixel TES based detector, placed 10 keV). The aim of the study has been to understand if the present detector design can be improved in order to enlarge the X-IFU scientific capability on an energy band wider than the TES array. This is beyond the CryoAC baseline, being this instrument aimed to operate as anticoincidence particle detector and not conceived to perform X-ray observations.

  6. Reduced field TE01 X-Band traveling wave window

    International Nuclear Information System (INIS)

    Fowkes, W.R.; Callin, R.S.; Tantawi, S.G.; Wright, E.L.

    1995-01-01

    The RF electric field is reduced by more than a factor of two using a pair of symmetrically located irises in a new type of klystron window operating in the TE 01 mode at X-Band. The advantages of this window over the usual TE 01 half-wave resonant window are discussed as well as theory and operating results. Ultra high purity alumina formed by the HIP process is used. This window has been successfully tested at 100 MW with a 1.5 microsecond RF pulse width and is being used on the XL series klystrons

  7. High-power comparison among brazed, clamped and electroformed X-band cavities

    Energy Technology Data Exchange (ETDEWEB)

    Spataro, B., E-mail: bruno.spataro@lnf.infn.it [INFN-LNF, Via E. Fermi 40, 00044 Frascati, Rome (Italy); Alesini, D.; Chimenti, V. [INFN-LNF, Via E. Fermi 40, 00044 Frascati, Rome (Italy); Dolgashev, V. [SLAC, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Higashi, Y. [KEK 1-1 Oho, Tsukuba, Ibaraki, 305-0801 (Japan); Migliorati, M.; Mostacci, A. [University of Rome Sapienza, Department of Fundamental and Applied Science for Engineering, Via A. Scarpa 14, 00185 Rome (Italy); Parodi, R. [INFN-Genova, Via Dodecaneso 33, 16146 Genova (Italy); Tantawi, S.G.; Yeremian, A.D. [SLAC, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

    2011-11-21

    We report the building procedure of X-band copper structures using the electroforming and electroplating techniques. These techniques allow the deposition of copper layers on a suitable die and they can be used to build RF structures avoiding the high temperature brazing step in the standard technique. We show the constructed prototypes and low power RF measurements and discuss the results of the high power tests at SLAC National Accelerator Laboratory.

  8. First-principle study of the electronic band structure and the effective mass of the ternary alloy GaxIn1-xP

    Science.gov (United States)

    Yang, H. Q.; Song, T. L.; Liang, X. X.; Zhao, G. J.

    2015-01-01

    In this work, the electronic band structure and the effective mass of the ternary alloy GaxIn1-xP are studied by the first principle calculations. The software QUANTUM ESPRESSO and the generalized gradient approximation (GGA) for the exchange correlations have been used in the calculations. We calculate the lattice parameter, band gap and effective mass of the ternary alloy GaxIn1-xP for the Ga composition x varying from 0.0 to 1.0 by the step of 0.125. The effect of the Ga composition on the lattice parameter and the electronic density of states are discussed. The results show that the lattice parameter varies with the composition almost linearly following the Vegard's law. A direct-to-indirect band-gap crossover is found to occur close to x = 0.7. The effective masses are also calculated at Γ(000) high symmetry point along the [100] direction. The results show that the band gap and the electron effective mass vary nonlinearly with composition x.

  9. Microscopic bosonization of band structures: x-ray processes beyond the Fermi edge

    Science.gov (United States)

    Snyman, Izak; Florens, Serge

    2017-11-01

    Bosonization provides a powerful analytical framework to deal with one-dimensional strongly interacting fermion systems, which makes it a cornerstone in quantum many-body theory. However, this success comes at the expense of using effective infrared parameters, and restricting the description to low energy states near the Fermi level. We propose a radical extension of the bosonization technique that overcomes both limitations, allowing computations with microscopic lattice Hamiltonians, from the Fermi level down to the bottom of the band. The formalism rests on the simple idea of representating the fermion kinetic term in the energy domain, after which it can be expressed in terms of free bosonic degrees of freedom. As a result, one- and two-body fermionic scattering processes generate anharmonic boson-boson interactions, even in the forward channel. We show that up to moderate interaction strengths, these non-linearities can be treated analytically at all energy scales, using the x-ray emission problem as a showcase. In the strong interaction regime, we employ a systematic variational solution of the bosonic theory, and obtain results that agree quantitatively with an exact diagonalization of the original one-particle fermionic model. This provides a proof of the fully microscopic character of bosonization, on all energy scales, for an arbitrary band structure. Besides recovering the known x-ray edge singularity at the emission threshold, we find strong signatures of correlations even at emission frequencies beyond the band bottom.

  10. Velocities of dislocation groups in very thin neutron-irradiated copper single crystals measured by slip line cinematography

    Energy Technology Data Exchange (ETDEWEB)

    Potthoff, H.H. (Technische Univ. Braunschweig (Germany, F.R.). Inst. fuer Metallphysik und Nukleare Festkoerperphysik)

    1983-05-16

    Slip line development on very thin flat single crystals of neutron-irradiated Cu (thickness down to only 15 to 20 ..mu..m, orientation for single glide, yield region, room temperature) is recorded by high-speed cinematography during tensile deformation. In such very thin crystals glide dislocations on the slip plane must be arranged in a rather simple way. Drops in tensile load occuring during initiation of single slip lines at the Lueders band front indicate that in the beginning of a slip line development dislocation groups traverse the whole glide plane in very short times. Evaluating the data measured for the slip line growth v/sub s/ >= 10 cm/s is found for screw dislocations and v/sub e/ >= v/sub s/ for edge dislocations. For later stages on thin crystals and for all stages on thick crystals (>= several 100 ..mu..m) slip line development is much slower and slip line show many cross slip events which then appear to control the mean velocity of the dislocations.

  11. X-band COSMO-SkyMed wind field retrieval, with application to coastal circulation modeling

    Directory of Open Access Journals (Sweden)

    A. Montuori

    2013-02-01

    Full Text Available In this paper, X-band COSMO-SkyMed© synthetic aperture radar (SAR wind field retrieval is investigated, and the obtained data are used to force a coastal ocean circulation model. The SAR data set consists of 60 X-band Level 1B Multi-Look Ground Detected ScanSAR Huge Region COSMO-SkyMed© SAR data, gathered in the southern Tyrrhenian Sea during the summer and winter seasons of 2010. The SAR-based wind vector field estimation is accomplished by resolving both the SAR-based wind speed and wind direction retrieval problems independently. The sea surface wind speed is retrieved by means of a SAR wind speed algorithm based on the azimuth cut-off procedure, while the sea surface wind direction is provided by means of a SAR wind direction algorithm based on the discrete wavelet transform multi-resolution analysis. The obtained wind fields are compared with ground truth data provided by both ASCAT scatterometer and ECMWF model wind fields. SAR-derived wind vector fields and ECMWF model wind data are used to construct a blended wind product regularly sampled in both space and time, which is then used to force a coastal circulation model of a southern Tyrrhenian coastal area to simulate wind-driven circulation processes. The modeling results show that X-band COSMO-SkyMed© SAR data can be valuable in providing effective wind fields for coastal circulation modeling.

  12. Determination of the impact of Bi content on the valence band energy of GaAsBi using x-ray photoelectron spectroscopy

    Directory of Open Access Journals (Sweden)

    K. Collar

    2017-07-01

    Full Text Available We investigate the change of the valence band energy of GaAs1-xBix (0<x<0.025 as a function of dilute bismuth (Bi concentration, x, using x-ray photoelectron spectroscopy (XPS. The change in the valence band energy per addition of 1 % Bi is determined for strained and unstrained thin films using a linear approximation applicable to the dilute regime. Spectroscopic ellipsometry (SE was used as a complementary technique to determine the change in GaAsBi bandgap resulting from Bi addition. Analysis of SE and XPS data together supports the conclusion that ∼75% of the reduction in the bandgap is in the valence band for a compressively strained, dilute GaAsBi thin film at room temperature.

  13. Generation of High-order Group-velocity-locked Vector Solitons

    OpenAIRE

    Jin, X. X.; Wu, Z. C.; Zhang, Q.; Li, L.; Tang, D. Y.; Shen, D. Y.; Fu, S. N.; Liu, D. M.; Zhao, L. M.

    2015-01-01

    We report numerical simulations on the high-order group-velocity-locked vector soliton (GVLVS) generation based on the fundamental GVLVS. The high-order GVLVS generated is characterized with a two-humped pulse along one polarization while a single-humped pulse along the orthogonal polarization. The phase difference between the two humps could be 180 degree. It is found that by appropriate setting the time separation between the two components of the fundamental GVLVS, the high-order GVLVS wit...

  14. Characteristics of light reflected from a dense ionization wave with a tunable velocity

    OpenAIRE

    Zhidkov, A.; Esirkepov, T.; Fujii, T.; Nemoto, K.; Koga, J.; Bulanov, S. V.

    2009-01-01

    An optically-dense ionization wave (IW) produced by two femtosecond laser pulses focused cylindrically and crossing each other is shown to be an efficient coherent x-ray converter. The resulting velocity of a quasi-plane IW in the vicinity of pulse intersection increases with the angle between the pulses from the group velocity of ionizing pulses to infinity allowing an easy tuning the wavelength of x-rays. The x-ray spectra of a converted, lower frequency coherent light change from the monoc...

  15. Structure of the crust beneath Cameroon, West Africa, from the joint inversion of Rayleigh wave group velocities and receiver functions

    Science.gov (United States)

    Tokam, Alain-Pierre K.; Tabod, Charles T.; Nyblade, Andrew A.; Julià, Jordi; Wiens, Douglas A.; Pasyanos, Michael E.

    2010-11-01

    The Cameroon Volcanic Line (CVL) consists of a linear chain of Tertiary to Recent, generally alkaline, volcanoes that do not exhibit an age progression. Here we study crustal structure beneath the CVL and adjacent regions in Cameroon using 1-D shear wave velocity models obtained from the joint inversion of Rayleigh wave group velocities and P-receiver functions for 32 broad-band seismic stations deployed between 2005 January and 2007 February. We find that (1) crustal thickness (35-39km) and velocity structure is similar beneath the CVL and the Pan African Oubanguides Belt to the south of the CVL, (2) crust is thicker (43-48km) under the northern margin of the Congo Craton and is characterized by shear wave velocities >=4.0kms-1 in its lower part and (3) crust is thinner (26-31km) under the Garoua rift and the coastal plain. In addition, a fast velocity layer (Vs of 3.6-3.8kms-1) in the upper crust is found beneath many of the seismic stations. Crustal structure beneath the CVL and the Oubanguides Belt is very similar to Pan African crustal structure in the Mozambique Belt, and therefore it appears not to have been modified significantly by the magmatic activity associated with the CVL. The crust beneath the coastal plain was probably thinned during the opening of the southern Atlantic Ocean, while the crust beneath the Garoua rift was likely thinned during the formation of the Benue Trough in the early Cretaceous. We suggest that the thickened crust and the thick mafic lower crustal layer beneath the northern margin of the Congo Craton may be relict features from a continent-continent collision along this margin during the formation of Gondwana.

  16. Peculiar Velocity Constraints from Five-band SZ Effect Measurements toward RX J1347.5-1145 with MUSIC and Bolocam from the CSO

    Science.gov (United States)

    Sayers, Jack; Zemcov, Michael; Glenn, Jason; Golwala, Sunil R.; Maloney, Philip R.; Siegel, Seth R.; Wheeler, Jordan; Bockstiegel, Clint; Brugger, Spencer; Czakon, Nicole G.; Day, Peter K.; Downes, Thomas P.; Duan, Ran P.; Gao, Jiansong; Hollister, Matthew I.; Lam, Albert; LeDuc, Henry G.; Mazin, Benjamin A.; McHugh, Sean G.; Miller, David A.; Mroczkowski, Tony K.; Noroozian, Omid; Nguyen, Hien T.; Radford, Simon J. E.; Schlaerth, James A.; Vayonakis, Anastasios; Wilson, Philip R.; Zmuidzinas, Jonas

    2016-04-01

    We present Sunyaev-Zel’dovich (SZ) effect measurements from wide-field images toward the galaxy cluster RX J1347.5-1145 obtained from the Caltech Submillimeter Observatory with the Multiwavelength Submillimeter Inductance Camera at 147, 213, 281, and 337 GHz and with Bolocam at 140 GHz. As part of our analysis, we have used higher frequency data from Herschel-SPIRE and previously published lower frequency radio data to subtract the signal from the brightest dusty star-forming galaxies behind RX J1347.5-1145 and from the AGN in RX J1347.5-1145’s BCG. Using these five-band SZ effect images, combined with X-ray spectroscopic measurements of the temperature of the intra-cluster medium (ICM) from Chandra, we constrain the ICM optical depth to be {τ }{{e}}={7.33}-0.97+0.96× {10}-3 and the ICM line of sight peculiar velocity to be {v}{pec}=-{1040}-840+870 km s-1. The errors for both quantities are limited by measurement noise rather than calibration uncertainties or astrophysical contamination, and significant improvements are possible with deeper observations. Our best-fit velocity is in good agreement with one previously published SZ effect analysis and in mild tension with the other, although some or all of that tension may be because that measurement samples a much smaller cluster volume. Furthermore, our best-fit optical depth implies a gas mass slightly larger than the Chandra-derived value, implying the cluster is elongated along the line of sight.

  17. Band alignment of HfO{sub 2}/AlN heterojunction investigated by X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Gang [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Wang, Hong, E-mail: ewanghong@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); CNRS-International-NTU-THALES Research Alliances/UMI 3288, 50 Nanyang Drive, Singapore 637553 (Singapore); Ji, Rong [Data Storage Institute, Agency for Science Technology and Research (A-STAR), Singapore 117608 (Singapore)

    2016-04-18

    The band alignment between AlN and Atomic-Layer-Deposited (ALD) HfO{sub 2} was determined by X-ray photoelectron spectroscopy (XPS). The shift of Al 2p core-levels to lower binding energies with the decrease of take-off angles θ indicated upward band bending occurred at the AlN surface. Based on the angle-resolved XPS measurements combined with numerical calculations, valence band discontinuity ΔE{sub V} of 0.4 ± 0.2 eV at HfO{sub 2}/AlN interface was determined by taking AlN surface band bending into account. By taking the band gap of HfO{sub 2} and AlN as 5.8 eV and 6.2 eV, respectively, a type-II band line-up was found between HfO{sub 2} and AlN.

  18. Ionizing radiation target groups of band 3 inserted into egg lecithin liposomes as determined by Raman spectroscopy

    International Nuclear Information System (INIS)

    Verma, S.P.; Sonwalkar, N.

    1993-01-01

    The purified integral membrane protein, band 3, from human erythrocytes was inserted into egg lecithin liposomes. The insertion of band 3 was determined from thermal transition data from the analysis of the C-H stretching region bands recorded at temperatures from 25 to -22 o C. Raman spectra show that band 3 considerably broadens and lowers the thermal transition of egg lecithin liposomes, suggesting the insertion of band 3. The band 3-inserted liposomes were irradiated with gamma-rays (40 Gy) and the radiation target groups were determined by the analysis of the structural sensitive Raman bands in the 1600-1700 cm -1 (amide I), 1200-1300 cm -1 (amide III) and 550-1030 cm -1 (side chain amino groups) regions. The radiation-sensitive groups as identified from Raman spectra in the region 550-1030 cm -1 are tyrosines and cysteines. The radiation-induced changes in the secondary structure were determined from amide I and III bands. Quantitative estimation using the curve fitting method shows that ban 3 contains 44% total helix, 48% beta strand and 8% undefined plus turns (error + or - 4%). The secondary structure changes to 35% total helix, 42% total beta-strand and 23% turned and undefined upon irradiating band 3 containing liposomes. (Author)

  19. Atmospheric dayglow diagnostics involving the O2(b-X) Atmospheric band emission: Global Oxygen and Temperature (GOAT) mapping

    Science.gov (United States)

    Slanger, T. G.; Pejaković, D. A.; Kostko, O.; Matsiev, D.; Kalogerakis, K. S.

    2017-03-01

    The terrestrial dayglow displays prominent emission features from the 0-0 and 1-1 bands of the O2 Atmospheric band system in the 760-780 nm region. We present an analysis of observations in this wavelength region recorded by the Space Shuttle during the Arizona Airglow Experiment. A major conclusion is that the dominant product of O(1D) + O2 energy transfer is O2(b, v = 1), a result that corroborates our previous laboratory studies. Moreover, critical to the interpretation of dayglow is the possible interference by N2 and N2+ bands in the 760-780 nm region, where the single-most important component is the N2 1PG 3-1 band that overlaps with the O2(b-X) 0-0 band. When present, this background must be accounted for to reveal the O2(b-X) 0-0 and 1-1 bands for altitudes at which the O2 and N2/N2+ emissions coincide. Finally, we exploit the very different collisional behavior of the two lowest O2(b) vibrational levels to outline a remote sensing technique that provides information on Atmospheric composition and temperature from space-based observations of the 0-0 and 1-1 O2 atmospheric bands.

  20. Creation of quasi-Dirac points in the Floquet band structure of bilayer graphene.

    Science.gov (United States)

    Cheung, W M; Chan, K S

    2017-06-01

    We study the Floquet quasi-energy band structure of bilayer graphene when it is illuminated by two laser lights with frequencies [Formula: see text] and [Formula: see text] using Floquet theory. We focus on the dynamical gap formed by the conduction band with Floquet index  =  -1 and the valence band with Floquet index  =  +1 to understand how Dirac points can be formed. It is found that the dynamical gap does not have rotation symmetry in the momentum space, and quasi-Dirac points, where the conduction and valence bands almost touch, can be created when the dynamical gap closes along some directions with suitably chosen radiation parameters. We derive analytical expressions for the direction dependence of the dynamical gaps using Lowdin perturbation theory to gain a better understanding of the formation of quasi-Dirac points. When both radiations are circularly polarized, the gap can be exactly zero along some directions, when only the first and second order perturbations are considered. Higher order perturbations can open a very small gap in this case. When both radiations are linearly polarized, the gap can be exactly zero up to the fourth order perturbation and more than one quasi-Dirac point is formed. We also study the electron velocity around a dynamical gap and show that the magnitude of the velocity drops to values close to zero when the k vector is near to the gap minimum. The direction of the velocity also changes around the gap minimum, and when the gap is larger in value the change in the velocity direction is more gradual. The warping effect does not affect the formation of a Dirac point along the k x axis, while it prevents its formation when there is phase shift between the two radiations.

  1. 7 CFR 29.2439 - Lugs (X Group).

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Lugs (X Group). 29.2439 Section 29.2439 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Grades § 29.2439 Lugs (X Group). This group consists of leaves that normally grow near...

  2. The relation of the broad band with the E2g phonon and superconductivity in the Mg(B1-xCx)2 compound

    International Nuclear Information System (INIS)

    Parisiades, P.; Lampakis, D.; Palles, D.; Liarokapis, E.; Karpinski, J.

    2007-01-01

    We have carried out an extensive micro-Raman study on Mg(B 1-x C x ) 2 single crystals, for carbon concentrations up to x=0.15. The E 2g symmetry broad band for pure MgB 2 at ∼600cm -1 disappears even for small doping levels (x=0.027) and two well-defined peaks in the high-energy side of this band play a major role in the Raman spectra of the substituted compounds. We propose that a two-mode behavior of the compound might be present, induced by the coupling of the observed phonons with the electronic bands

  3. Demonstration of 352 Gbit/s Photonically-enabled D-Band Wireless Delivery in one 2x2 MIMO System

    DEFF Research Database (Denmark)

    Puerta Ramírez, Rafael; Yu, Jianjun; Li, Xinying

    2017-01-01

    First demonstration of photonically-enabled independent side-bands D-Band wireless transmission up to 352 Gbit/s with a BER below 3.8×10-3. These results were achieved by means of advanced DSP and antenna polarization multiplexing (2x2 MIMO)....

  4. Autopsy on an RF-Processed X-band Travelling Wave Structure

    International Nuclear Information System (INIS)

    Le Pimpec, Frederic

    2002-01-01

    In an effort to locate the cause(s) of high electric-field breakdown in x-band accelerating structures, we have cleanly-autopsied (no debris added by post-operation structure disassembly) an RF-processed structure. Macroscopic localization provided operationally by RF reflected wave analysis and acoustic sensor pickup was used to connect breakdowns to autopsied crater damage areas. Surprisingly, the microscopic analyses showed breakdown craters in areas of low electric field. High currents induced by the magnetic field on sharp corners of the input coupler appears responsible for the extreme breakdown damage observed

  5. 7 CFR 29.6128 - Straight Stripped (X Group).

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Straight Stripped (X Group). 29.6128 Section 29.6128... REGULATIONS TOBACCO INSPECTION Standards Grades § 29.6128 Straight Stripped (X Group). This group consists of..., and tolerances X1 Fine Quality Straight Stripped. Heavy, ripe, firm, semielastic, normal strength and...

  6. Correlated Radial Velocity and X-Ray Variations in HD 154791/4U 1700+24

    Science.gov (United States)

    Galloway, Duncan K.; Sokoloski, J. L.; Kenyon, Scott J.

    2002-12-01

    We present evidence for approximately 400 day variations in the radial velocity of HD 154791 (V934 Her), the suggested optical counterpart of 4U 1700+24. The variations are correlated with the previously reported ~400 day variations in the X-ray flux of 4U 1700+24, which supports the association of these two objects, as well as the identification of this system as the second known X-ray binary in which a neutron star accretes from the wind of a red giant. The HD 154791 radial velocity variations can be fitted with an eccentric orbit with period 404+/-3 days, amplitude K=0.75+/-0.12kms-1, and eccentricity e=0.26+/-0.15. There are also indications of variations on longer timescales >~2000 days. We have reexamined all available All-Sky Monitor (ASM) data following an unusually large X-ray outburst in 1997-1998 and confirm that the 1 day averaged 2-10 keV X-ray flux from 4U 1700+24 is modulated with a period of 400+/-20 days. The mean profile of the persistent X-ray variations was approximately sinusoidal, with an amplitude of 0.108+/-0.012 ASM counts s-1 (corresponding to 31% rms). The epoch of X-ray maximum was approximately 40 days after the time of periastron, according to the eccentric orbital fit. If the 400 day oscillations from HD 154791/4U 1700+24 are due to orbital motion, then the system parameters are probably close to those of the only other neutron star symbiotic-like binary, GX 1+4. We discuss the similarities and differences between these two systems.

  7. Analysis of X-band radar images for the detection of the reflected and diffracted waves in coastal zones

    Science.gov (United States)

    Ludeno, Giovanni; Natale, Antonio; Soldovieri, Francesco; Vicinanza, Diego; Serafino, Francesco

    2014-05-01

    The observation of nearshore waves and the knowledge of the sea state parameters can play a crucial role for the safety of harbors and ocean engineering. In the last two decades, different algorithms for the estimation of sea state parameters, surface currents and bathymetry from X-band radar data have been developed and validated [1, 2]. The retrieval of ocean wave parameters such as significant height, period, direction and wavelength of the dominant wave is based on the spectral analysis of data sequences collected by nautical X-band radars [3]. In particular, the reconstruction of the wave motion is carried out through the inversion procedure explained in [1-3], which exploits the dispersion relationship to define a band pass filter used to separate the energy associated with the ocean waves from the background noise. It is worth to note that the shape of such a band pass filter depends upon the value of both the surface currents and bathymetry; in our reconstruction algorithm these parameters are estimated through the (Normalized Scalar Product) procedure [1], which outperforms other existing methods (e.g., the Least Squares) [4]. From the reconstructed wave elevation sequences we can get the directional spectrum that provides useful information (i.e., wavelength, period, direction and amplitude) relevant to the main waves contributing to the wave motion. Of course, in coastal zones a number of diffraction and reflection phenomena can be observed, due to sea-waves impinging obstacles as jetties, breakwaters and boats. In the present paper we want to show the capability to detect reflected and diffracted sea-waves offered by the processing of X-band radar data. Further details relevant to the obtained results will be provided in the full paper and at the conference time. References [1] F. Serafino, C. Lugni, F. Soldovieri, "A novel strategy for the surface current determination from marine X-Band radar data", IEEE Geosci. and Remote Sensing Letters, vol. 7, no

  8. Free-surface velocity measurements using an optically recording velocity interferometer

    International Nuclear Information System (INIS)

    Lu Jianxin; Wang Zhao; Liang Jing; Shan Yusheng; Zhou Chuangzhi; Xiang Yihuai; Lu Ze; Tang Xiuzhang

    2006-01-01

    An optically recording velocity interferometer system (ORVIS) was developed for the free-surface velocity measurements in the equation of state experiments. The time history of free-surface velocity could be recorded by the electronic streak camera. In the experiments, ORVIS got a 179 ps time resolution, and a higher time resolution could be got by minimizing the delay time. The equation of state experiments were carried out on the high power excimer laser system called 'Heaven I' with laser wavelength of 248.4 nm, pulse duration of 25 ns and maximum energy 158 J. Free-surface velocity of 20 μm thick iron got 3.86 km/s with laser intensity of 6.24 x 10 11 W·cm -2 , and free-surface velocity of 100 μm thick aluminum with 100 μm CH foil at the front got 2.87 km/s with laser intensity 7.28 x 10 11 W·cm -2 . (authors)

  9. Density Functional Theory Calculation of the Band Alignment of (101̅0) In(x)Ga(1-x)N/Water Interfaces.

    Science.gov (United States)

    Meng, Andrew C; Cheng, Jun; Sprik, Michiel

    2016-03-03

    Conduction band edge (CBE) and valence band edge (VBE) positions of InxGa1-xN photoelectrodes were computed using density functional theory methods. The band edges of fully solvated GaN and InN model systems were aligned with respect to the standard hydrogen electrode using a molecular dynamics hydrogen electrode scheme applied earlier to TiO2/water interfaces. Similar to the findings for TiO2, we found that the Purdew-Burke-Ernzerhof (PBE) functional gives a VBE potential which is too negative by 1 V. This cathodic bias is largely corrected by application of the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional containing a fraction of Hartree-Fock exchange. The effect of a change of composition was investigated using simplified model systems consisting of vacuum slabs covered on both sides by one monolayer of H2O. The CBE was found to vary linearly with In content. The VBE, in comparison, is much less sensitive to composition. The data show that the band edges straddle the hydrogen and oxygen evolution potentials for In fractions less than 47%. The band gap was found to exceed 2 eV for an In fraction less than 54%.

  10. Hydrostatic pressure effects on the {gamma}-X conduction band mixing and the binding energy of a donor impurity in GaAs-Ga{sub 1-x}Al{sub x}As quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Duque, C.A. [Instituto de Fisica, Universidad de Antioquia, AA 1226, Medellin (Colombia); Lopez, S.Y. [Facultad de Educacion, Universidad de Antioquia, AA 1226, Medellin (Colombia); Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, C.P. 62210, Cuernavaca (Mexico)

    2007-06-15

    Mixing between {gamma} and X valleys of the conduction band in GaAs-Ga{sub 1-x}Al{sub x}As quantum wells is investigated taken into account the effect of applied hydrostatic pressure. This effect is introduced via the pressure-dependent values of the corresponding energy gaps and the main band parameters. The mixing is considered along the lines of a phenomenological model. Variation of the confined ground state in the well as a function of the pressure is reported. The dependencies of the variationally calculated binding energy of a donor impurity with the hydrostatic pressure and well width are also presented. It is shown that the inclusion of the {gamma}-X mixing explains the non-linear behavior in the photoluminescence peak of confined exciton states that has been observed for pressures above 20 kbar. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. What band rocks the MTB? (Invited)

    Science.gov (United States)

    Kind, J.; García-Rubio, I.; Gehring, A. U.

    2013-12-01

    Magnetotactic bacteria (MTB) are a polyphyletic group of bacteria that have been found in marine and lacustrine environments and soils [e.g. 1]. The hallmark of MTB is their intracellular formation of magnetosomes, single-domain ferrimagnetic particles that are aligned in chains. The chain configuration generates a strong magnetic dipole, which is used as magnetic compass to move the MTB into their favorable habit. The term band corresponds to a frequency window of microwaves in the gigahertz (GHz) range. Ferromagnetic resonance (FMR) spectroscopy uses the microwave absorption in a magnetic field to analyze the anisotropy properties and the domain state of magnetic materials. Specific microwave frequency causes absorption in a characteristic magnetic field range. For the investigation of MTB we use S-band (4.02 GHz), X-band (9.47 GHz), and Q-band (34.16 GHz). Experiments on cultured MTB and on sediment samples of Holocene age showed that absorption in X- and Q-band occurs when the sample is in a saturated or nearly saturated state [2, 3]. By contrast, absorption in the S-band appears in lower magnetic fields, where the sample is far from saturation. All FMR spectra show two distinct low-field features that can be assigned to magnetite particles in chains, aligned parallel and perpendicular to the external magnetic field. The detailed separation of the parallel and perpendicular components in the bulk samples is hampered, because of the random orientation of the chains in the sample. The comparison of S-, X-, and Q-band shows that the lower the frequency the better the separation of the components. In the S-band FMR spectroscopy, the separation of chains parallel to the external magnetic field is supported by the internal field of the sample. This field is caused by the remanence that contributes to the external magnetic field to fulfill the resonance condition [3,4]. Considering the different FMR responses, it can be postulated that a lower microwave frequency

  12. Performance analysis of high efficiency InxGa1-xN/GaN intermediate band quantum dot solar cells

    Science.gov (United States)

    Chowdhury, Injamam Ul Islam; Sarker, Jith; Shifat, A. S. M. Zadid; Shuvro, Rezoan A.; Mitul, Abu Farzan

    2018-06-01

    In this subsistent fifth generation era, InxGa1-xN/GaN based materials have played an imperious role and become promising contestant in the modernistic fabrication technology because of some of their noteworthy attributes. On our way of illustrating the performance, the structure of InxGa1-xN/GaN quantum dot (QD) intermediate band solar cell (IBSC) is investigated by solving the Schrödinger equation in light of the Kronig-Penney model. In comparison with p-n homojunction and heterojunction solar cells, InxGa1-xN/GaN IBQD solar cell manifests larger power conversion efficiency (PCE). PCE strongly depends on position and width of the intermediate bands (IB). Position of IBs can be controlled by tuning the size of QDs and the Indium content of InxGa1-xN whereas, width of IB can be controlled by tuning the interdot distance. PCE can also be controlled by tuning the position of fermi energy bands as well as changing the doping concentration. In this work, maximum conversion efficiency is found approximately 63.2% for a certain QD size, interdot distance, Indium content and doping concentration.

  13. Complex Permittivity of Polyaniline-Carbon Nanotube and Nanofibre Composites in the X-band. PMMA Composites

    National Research Council Canada - National Science Library

    Makeiff, Darren A; Huber, Trisha; Saville, Paul

    2005-01-01

    ... the complex permittivity from transmission-reflection waveguide measurements in the X-band (8-12 GHz). PMMA composites containing PAni-MWNT or PAni-CNFs poorer, while PMMA composites containing PAni and MWNT mixed ex situ...

  14. S-band linac-based X-ray source with {pi}/2-mode electron linac

    Energy Technology Data Exchange (ETDEWEB)

    Deshpande, Abhay, E-mail: abhay@post.kek.jp [Department of Accelerator Science, School of High Energy Accelerator Science, Graduate University for Advanced Studies, Shonan International Village, Hayama, Miura, Kanagawa 240-0193 (Japan); Society for Applied Microwave Electronic Engineering and Research (SAMEER), R and D Laboratory of the Government of India, IIT Campus, Powai, Mumbai 400 076 (India); Araki, Sakae [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Dixit, Tanuja [Society for Applied Microwave Electronic Engineering and Research (SAMEER), R and D Laboratory of the Government of India, IIT Campus, Powai, Mumbai 400 076 (India); Fukuda, Masafumi [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Krishnan, R; Pethe, Sanjay [Society for Applied Microwave Electronic Engineering and Research (SAMEER), R and D Laboratory of the Government of India, IIT Campus, Powai, Mumbai 400 076 (India); Sakaue, Kazuyuki [Waseda University, Shinjuku-ku, Tokyo 169-8555 (Japan); Terunuma, Nobuhiro; Urakawa, Junji [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Washio, Masakazu [Waseda University, Shinjuku-ku, Tokyo 169-8555 (Japan)

    2011-05-01

    The activities with the compact X-ray source are attracting more attention, particularly for the applications of the source in medical fields. We propose the fabrication of a compact X-ray source using the SAMEER electron linear accelerator and the KEK laser undulator X-ray source (LUCX) technologies. The linac developed at SAMEER is a standing wave side-coupled S-band linac operating in the {pi}/2 mode. In the proposed system, a photocathode RF gun will inject bunches of electrons in the linac to accelerate and achieve a high-energy, low-emittance beam. This beam will then interact with the laser in the laser cavity to produce X-rays of a type well suited for various applications. The side-coupled structure will make the system more compact, and the {pi}/2 mode of operation will enable a high repetition rate operation, which will help to increase the X-ray yield.

  15. Donor impurity-related optical absorption spectra in GaAs-Ga{sub 1-x}Al{sub x}As quantum wells: hydrostatic pressure and {gamma}-X conduction band mixing effects

    Energy Technology Data Exchange (ETDEWEB)

    Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, C.P. 62209, Cuernavaca, MOR (Mexico); Inst. de Ciencia de Materiales de Madrid, CSIC, Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain); Lopez, S.Y. [Fac. de Educacion, Universidad de Antioquia, AA 1226, Medellin (Colombia); Duque, C.A. [Inst. de Fisica, Universidad de Antioquia, AA 1226, Medellin (Colombia); Velasco, V.R. [Inst. de Ciencia de Materiales de Madrid, CSIC, Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain)

    2007-07-01

    Using a variational procedure within the effective mass approximation, the mixing between the {gamma} and X conduction band valleys in GaAs-Ga{sub 1-x}Al{sub x}As quantum wells is investigated by taking into account the effect of applied hydrostatic pressure. Some optical properties such as donor and/or acceptor binding energy and impurity-related transition energies are calculated and comparisons with available experimental data are presented. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Measurement of ZnO/Al2O3 Heterojunction Band Offsets by in situ X-Ray Photoelectron Spectroscopy

    International Nuclear Information System (INIS)

    Lei Hong-Wen; Zhang Hong; Wang Xue-Min; Zhao Yan; Yan Da-Wei; Jiang Zhong-Qian; Yao Gang; Zeng Ti-Xian; Wu Wei-Dong

    2013-01-01

    ZnO films are grown on c-sapphire substrates by laser molecular beam epitaxy. The band offsets of the ZnO/Al 2 O 3 heterojunction are studied by in situ x-ray photoelectron spectroscopy. The valence band of Al 2 O 3 is found to be 3.59±0.05eV below that of ZnO. Together with the resulting conduction band offset of 2.04±0.05eV, this indicates that a type-I staggered band line exists at the ZnO/Al 2 O 3 heterojunction

  17. Banding together: an investigation of post-surgery support groups for laparoscopic adjustable gastric banding patients

    Directory of Open Access Journals (Sweden)

    Melissa Opolski

    2014-09-01

    Full Text Available Though advocated as useful for patients, there is little in the literature regarding the use and effectiveness of bariatric support groups. This study investigated characteristics and experiences of bariatric patients who did and did not attend offered groups. Seventy-eight postoperative laparoscopic adjustable gastric banding patients from a private bariatric clinic completed mailed self-report questionnaires. Almost 60% reported having attended the clinic groups, with most wanting to meet other patients and obtain information rather than access psychological assistance. Participants reported generally positive experiences of attending. Nonattendance was often attributed to practical barriers. Satisfaction with support from others was not related to past or predicted future attendance, but higher psychological distress was related to and predictive of greater intention to attend future groups. Likely future attenders also held more positive beliefs about the groups than those who were unlikely to attend. Further research is required into potential positive and negative consequences of attendance, and characteristics of those who are likely to benefit or be harmed by attending. Interventions addressing stereotypes about support groups may help patients make informed decisions about whether to attend a bariatric support group.

  18. Multifunctional Binary Monolayers Ge xP y: Tunable Band Gap, Ferromagnetism, and Photocatalyst for Water Splitting.

    Science.gov (United States)

    Li, Pengfei; Zhang, Wei; Li, Dongdong; Liang, Changhao; Zeng, Xiao Cheng

    2018-06-04

    The most stable structures of two-dimensional Ge x P y and Ge x As y monolayers with different stoichiometries (e.g., GeP, GeP 2 , and GeP 3 ) are explored systematically through the combination of the particle-swarm optimization technique and density functional theory optimization. For GeP 3 , we show that the newly predicted most stable C2/ m structure is 0.16 eV/atom lower in energy than the state-of-the-art P3̅m1 structure reported previously ( Nano Lett. 2017, 17, 1833). The computed electronic band structures suggest that all the stable and metastable monolayers of Ge x P y are semiconductors with highly tunable band gaps under the biaxial strain, allowing strain engineering of their band gaps within nearly the whole visible-light range. More interestingly, the hole doping can convert the C2/ m GeP 3 monolayer from nonmagnetic to ferromagnetic because of its unique valence band structure. For the GeP 2 monolayer, the predicted most stable Pmc2 1 structure is a (quasi) direct-gap semiconductor that possesses a high electron mobility of ∼800 cm 2 V -1 s -1 along the k a direction, which is much higher than that of MoS 2 (∼200 cm 2 V -1 s -1 ). More importantly, the Pmc2 1 GeP 2 monolayer not only can serve as an n-type channel material in field-effect transistors but also can be an effective catalyst for splitting water.

  19. Fabrication and Testing of Pyramidal X- Band Standard Horn Antenna

    Directory of Open Access Journals (Sweden)

    Hasan F. Khazaal

    2017-11-01

    Full Text Available Standard horn antennas are an important device to evaluate many types of antennas, since they are used as a reference to any type of antennas within the microwave frequency bands. In this project the fabrication process and tests of standard horn antenna operating at X-band frequencies have been proposed. The fabricated antenna passed through multi stages of processing of its parts until assembling the final product. These stages are (milling, bending, fitting and welding. The assembled antenna subjected to two types of tests to evaluate its performance. The first one is the test by two port network analyzer to point out S & Z parameters, input resistance, and the voltage standing wave ratio of the horn, while the second test was done using un-echoic chamber to measure the gain, side lobes level and the half power beam width. The results of testing come nearly as a theoretical value of the most important of antenna parameters, like; gain, side lobe level, -3 dB beam width, return loss and voltage standing wave ratio "VSWR", input Impedance.

  20. Landsat Data Continuity Mission (LDCM) - Optimizing X-Band Usage

    Science.gov (United States)

    Garon, H. M.; Gal-Edd, J. S.; Dearth, K. W.; Sank, V. I.

    2010-01-01

    The NASA version of the low-density parity check (LDPC) 7/8-rate code, shortened to the dimensions of (8160, 7136), has been implemented as the forward error correction (FEC) schema for the Landsat Data Continuity Mission (LDCM). This is the first flight application of this code. In order to place a 440 Msps link within the 375 MHz wide X band we found it necessary to heavily bandpass filter the satellite transmitter output . Despite the significant amplitude and phase distortions that accompanied the spectral truncation, the mission required BER is maintained at LDPC code and the amplitude and phase compensation provided in the receiver. Similar results were obtained with receivers from several vendors.

  1. Optical spectra and band structure of Ag(x)Ga(x)Ge(1-x)Se2 (x = 0.333, 0.250, 0.200, 0.167) single crystals: experiment and theory.

    Science.gov (United States)

    Reshak, A H; Parasyuk, O V; Fedorchuk, A O; Kamarudin, H; Auluck, S; Chyský, J

    2013-12-05

    Theoretical and experimental studies of the Ag(x)Ga(x)Ge(1-x)Se2 (x = 0.333, 0.250, 0.200, 0.167) single crystals are performed. These crystals possess a lot of intrinsic defects which are responsible for their optoelectronic features. The theoretical investigations were performed by means of DFT calculations using different exchange-correlation potentials. The experimental studies were carried out using the modulated VUV ellipsometry for dielectric constants and birefringence studies. The comparison of the structure obtained from X-ray with the theoretically optimized structure is presented. The crucial role of the intrinsic defect states is manifested in the choice of the exchange correlation potential used. The data may be applicable for a large number of the ternary chalcogenides which are sensitive to the presence of the local disordered states near the band edges.

  2. Review of studies on conventional linear colliders in the S- and X-Band regime

    International Nuclear Information System (INIS)

    Loew, G.A.

    1992-07-01

    This paper gives a status report on the conventional approaches to linear colliders at DESY, KEK, SLAC and INP-Protvino in the S- and X-Band regime. Critical topics are reviewed and a discussion of global issues such as future R ampersand D requirements is included

  3. The transfer to technology to manufacture the disk of X-band accelerator structure

    International Nuclear Information System (INIS)

    Ueno, Kenji; Kawamata, Hiroshi; Takatomi, Toshikazu; Kume, Tatsuya; Funahashi, Yoshisato

    2005-01-01

    We research the transfer of manufacturing technology on X-band structure disks. From this issue we confirm that the venders will be able to manufacture disks when they get the process sheet method and drawings. More it is clear that we have to consider the automation process in order to get the repeatability of the disks. (author)

  4. Lithospheric structure of the Arabian Shield and Platform from complete regional waveform modelling and surface wave group velocities

    Science.gov (United States)

    Rodgers, Arthur J.; Walter, William R.; Mellors, Robert J.; Al-Amri, Abdullah M. S.; Zhang, Yu-Shen

    1999-09-01

    Regional seismic waveforms reveal significant differences in the structure of the Arabian Shield and the Arabian Platform. We estimate lithospheric velocity structure by modelling regional waveforms recorded by the 1995-1997 Saudi Arabian Temporary Broadband Deployment using a grid search scheme. We employ a new method whereby we narrow the waveform modelling grid search by first fitting the fundamental mode Love and Rayleigh wave group velocities. The group velocities constrain the average crustal thickness and velocities as well as the crustal velocity gradients. Because the group velocity fitting is computationally much faster than the synthetic seismogram calculation this method allows us to determine good average starting models quickly. Waveform fits of the Pn and Sn body wave arrivals constrain the mantle velocities. The resulting lithospheric structures indicate that the Arabian Platform has an average crustal thickness of 40 km, with relatively low crustal velocities (average crustal P- and S-wave velocities of 6.07 and 3.50 km s^-1 , respectively) without a strong velocity gradient. The Moho is shallower (36 km) and crustal velocities are 6 per cent higher (with a velocity increase with depth) for the Arabian Shield. Fast crustal velocities of the Arabian Shield result from a predominantly mafic composition in the lower crust. Lower velocities in the Arabian Platform crust indicate a bulk felsic composition, consistent with orogenesis of this former active margin. P- and S-wave velocities immediately below the Moho are slower in the Arabian Shield than in the Arabian Platform (7.9 and 4.30 km s^-1 , and 8.10 and 4.55 km s^-1 , respectively). This indicates that the Poisson's ratios for the uppermost mantle of the Arabian Shield and Platform are 0.29 and 0.27, respectively. The lower mantle velocities and higher Poisson's ratio beneath the Arabian Shield probably arise from a partially molten mantle associated with Red Sea spreading and continental

  5. Attempt at interpreting some optical absorption bands in X-ray irradiated fluorine

    International Nuclear Information System (INIS)

    Allain, Yves

    1959-01-01

    According to the results of one of our experiments, the 575 mμ absorption band of fluorine irradiated with X-Rays seams due to F - ion vacancies. Our goal has been to find a color centers model in fluorine colored in various conditions. Reprint of a paper published in Comptes rendus des seances de l'Academie des Sciences, t. 248, p. 2318-2320, sitting of Aril 20, 1959 [fr

  6. Velocity gradient induced line splitting in x-ray emission accompanying plasma-wall interaction

    Czech Academy of Sciences Publication Activity Database

    Šmíd, Michal; Renner, Oldřich; Liska, R.

    2013-01-01

    Roč. 125, Aug (2013), s. 38-44 ISSN 0022-4073 R&D Projects: GA ČR GAP205/10/0814; GA ČR GAP205/11/0571 Institutional support: RVO:68378271 Keywords : laser-produced plasmas * x-ray spectroscopy * plasma-wall interaction * spectral line profiles * Doppler shift * ion velocity gradients Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.288, year: 2013

  7. InAs quantum dot growth on Al{sub x}Ga{sub 1−x}As by metalorganic vapor phase epitaxy for intermediate band solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Jakomin, R., E-mail: robertojakomin@xerem.ufrj.br [Campus de Xerém, Universidade Federal do Rio de Janeiro, UFRJ, Duque de Caxias-RJ (Brazil); Campus de Xerém, Universidade Federal do Rio de Janeiro, UFRJ, Duque de Caxias-RJ (Brazil); Kawabata, R. M. S.; Souza, P. L. [Instituto Nacional de Ciência e Tecnologia de Nanodispositivos Semicondutoires–DISSE–PUC-Rio, RJ (Brazil); Pontificia Universidade Católica do Rio de Janeiro, Marques de São Vicente 225, Rio de Janeiro, 22452-900 RJ (Brazil); Mourão, R. T.; Pires, M. P. [Instituto Nacional de Ciência e Tecnologia de Nanodispositivos Semicondutoires–DISSE–PUC-Rio, RJ (Brazil); Instituto de Física, Universidade Federal do Rio de Janeiro, UFRJ, Rio de Janeiro-RJ (Brazil); Micha, D. N. [Instituto Nacional de Ciência e Tecnologia de Nanodispositivos Semicondutoires–DISSE–PUC-Rio, RJ (Brazil); Instituto de Física, Universidade Federal do Rio de Janeiro, UFRJ, Rio de Janeiro-RJ (Brazil); Coordenação de Licenciatura em Física, CEFET/RJ, Petrópolis-RJ (Brazil); Xie, H.; Fischer, A. M.; Ponce, F. A. [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States)

    2014-09-07

    InAs quantum dot multilayers have been grown using Al{sub x}Ga{sub 1−x}As spacers with dimensions and compositions near the theoretical values for optimized efficiencies in intermediate band photovoltaic cells. Using an aluminium composition of x = 0.3 and InAs dot vertical dimensions of 5 nm, transitions to an intermediate band with energy close to the ideal theoretical value have been obtained. Optimum size uniformity and density have been achieved by capping the quantum dots with GaAs following the indium-flush method. This approach has also resulted in minimization of crystalline defects in the epilayer structure.

  8. Challenges in X-band Weather Radar Data Calibration

    DEFF Research Database (Denmark)

    Thorndahl, Søren; Rasmussen, Michael R.

    2009-01-01

    Application of weather radar data in urban hydrology is evolving and radar data is now applied for both modelling, analysis and real time control purposes. In these contexts, it is all-important that the radar data well calibrated and adjusted in order to obtain valid quantitative precipitation e...... estimates. This paper compares two calibration procedures for a small marine X-band radar by comparing radar data with rain gauge data. Validation shows a very good consensus with regards to precipitation volumes, but more diverse results on peak rain intensities.......Application of weather radar data in urban hydrology is evolving and radar data is now applied for both modelling, analysis and real time control purposes. In these contexts, it is all-important that the radar data well calibrated and adjusted in order to obtain valid quantitative precipitation...

  9. Random forest wetland classification using ALOS-2 L-band, RADARSAT-2 C-band, and TerraSAR-X imagery

    Science.gov (United States)

    Mahdianpari, Masoud; Salehi, Bahram; Mohammadimanesh, Fariba; Motagh, Mahdi

    2017-08-01

    Wetlands are important ecosystems around the world, although they are degraded due both to anthropogenic and natural process. Newfoundland is among the richest Canadian province in terms of different wetland classes. Herbaceous wetlands cover extensive areas of the Avalon Peninsula, which are the habitat of a number of animal and plant species. In this study, a novel hierarchical object-based Random Forest (RF) classification approach is proposed for discriminating between different wetland classes in a sub-region located in the north eastern portion of the Avalon Peninsula. Particularly, multi-polarization and multi-frequency SAR data, including X-band TerraSAR-X single polarized (HH), L-band ALOS-2 dual polarized (HH/HV), and C-band RADARSAT-2 fully polarized images, were applied in different classification levels. First, a SAR backscatter analysis of different land cover types was performed by training data and used in Level-I classification to separate water from non-water classes. This was followed by Level-II classification, wherein the water class was further divided into shallow- and deep-water classes, and the non-water class was partitioned into herbaceous and non-herbaceous classes. In Level-III classification, the herbaceous class was further divided into bog, fen, and marsh classes, while the non-herbaceous class was subsequently partitioned into urban, upland, and swamp classes. In Level-II and -III classifications, different polarimetric decomposition approaches, including Cloude-Pottier, Freeman-Durden, Yamaguchi decompositions, and Kennaugh matrix elements were extracted to aid the RF classifier. The overall accuracy and kappa coefficient were determined in each classification level for evaluating the classification results. The importance of input features was also determined using the variable importance obtained by RF. It was found that the Kennaugh matrix elements, Yamaguchi, and Freeman-Durden decompositions were the most important parameters

  10. Compaction bands in shale revealed through digital volume correlation of time-resolved X-ray tomography scans

    Science.gov (United States)

    McBeck, J.; Kobchenko, M.; Hall, S.; Tudisco, E.; Cordonnier, B.; Renard, F.

    2017-12-01

    Previous studies have identified compaction bands primarily within sandstones, and in fewer instances, within other porous rocks and sediments. Using Digital Volume Correlation (DVC) of X-ray microtomography scans, we find evidence of localized zones of high axial contraction that form tabular structures sub-perpendicular to maximum compression, σ1, in Green River shale. To capture in situ strain localization throughout loading, two shale cores were deformed in the HADES triaxial deformation apparatus installed on the X-ray microtomography beamline ID19 at the European Synchrotron Radiation Facility. In these experiments, we increase σ1 in increments of two MPa, with constant confining pressure (20 MPa), until the sample fails in macroscopic shear. After each stress step, a 3D image of the sample inside the rig is acquired at a voxel resolution of 6.5 μm. The evolution of lower density regions within 3D reconstructions of linear attenuation coefficients reveal the development of fractures that fail with some opening. If a fracture produces negligible dilation, it may remain undetected in image segmentation of the reconstructions. We use the DVC software TomoWarp2 to identify undetected fractures and capture the 3D incremental displacement field between each successive pair of microtomography scans acquired in each experiment. The corresponding strain fields reveal localized bands of high axial contraction that host minimal shear strain, and thus match the kinematic definition of compaction bands. The bands develop sub-perpendicular to σ1 in the two samples in which pre-existing bedding laminations were oriented parallel and perpendicular to σ1. As the shales deform plastically toward macroscopic shear failure, the number of bands and axial contraction within the bands increase, while the spacing between the bands decreases. Compaction band development accelerates the rate of overall axial contraction, increasing the mean axial contraction throughout the sample

  11. Valence band offset of wurtzite InN/SrTiO3 heterojunction measured by x-ray photoelectron spectroscopy

    Directory of Open Access Journals (Sweden)

    Li Zhiwei

    2011-01-01

    Full Text Available Abstract The valence band offset (VBO of wurtzite indium nitride/strontium titanate (InN/SrTiO3 heterojunction has been directly measured by x-ray photoelectron spectroscopy. The VBO is determined to be 1.26 ± 0.23 eV and the conduction band offset is deduced to be 1.30 ± 0.23 eV, indicating the heterojunction has a type-I band alignment. The accurate determination of the valence and conduction band offsets paves a way to the applications of integrating InN with the functional oxide SrTiO3.

  12. Mars Global Surveyor Ka-Band Frequency Data Analysis

    Science.gov (United States)

    Morabito, D.; Butman, S.; Shambayati, S.

    2000-01-01

    The Mars Global Surveyor (MGS) spacecraft, launched on November 7, 1996, carries an experimental space-to-ground telecommunications link at Ka-band (32 GHz) along with the primary X-band (8.4 GHz) downlink. The signals are simultaneously transmitted from a 1.5-in diameter parabolic high gain antenna (HGA) on MGS and received by a beam-waveguide (BWG) R&D 34-meter antenna located in NASA's Goldstone Deep Space Network (DSN) complex near Barstow, California. The projected 5-dB link advantage of Ka-band relative to X-band was confirmed in previous reports using measurements of MGS signal strength data acquired during the first two years of the link experiment from December 1996 to December 1998. Analysis of X-band and Ka-band frequency data and difference frequency (fx-fka)/3.8 data will be presented here. On board the spacecraft, a low-power sample of the X-band downlink from the transponder is upconverted to 32 GHz, the Ka-band frequency, amplified to I-W using a Solid State Power Amplifier, and radiated from the dual X/Ka HGA. The X-band signal is amplified by one of two 25 W TWTAs. An upconverter first downconverts the 8.42 GHz X-band signal to 8 GHz and then multiplies using a X4 multiplier producing the 32 GHz Ka-band frequency. The frequency source selection is performed by an RF switch which can be commanded to select a VCO (Voltage Controlled Oscillator) or USO (Ultra-Stable Oscillator) reference. The Ka-band frequency can be either coherent with the X-band downlink reference or a hybrid combination of the USO and VCO derived frequencies. The data in this study were chosen such that the Ka-band signal is purely coherent with the X-band signal, that is the downconverter is driven by the same frequency source as the X-band downlink). The ground station used to acquire the data is DSS-13, a 34-meter BWG antenna which incorporates a series of mirrors inside beam waveguide tubes which guide the energy to a subterranean pedestal room, providing a stable environment

  13. Turbulent transport reduction by E x B velocity shear during edge plasma biasing in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Van Oost, G. [Dept. of Applied Physics, Ghent Univ., Ghent (Belgium); Adamek, J.; Antoni, V.; Balan, P.; Boedo, J.A.; Devynck, P.; Duran, I.; Eliseev, L.; Gunn, J.P.; Hron, M.; Ionita, C.; Jachmich, S.; Kirnev, G.S.; Martines, E.; Melnikov, A.; Peleman, P.; Schrittwieser, R.; Silva, C.; Stoeckel, J.; Tendler, M.; Varandas, C.; Van Schoor, M.; Vershkov, V.; Weynants, R.R.

    2004-07-01

    Experiments in the tokamaks TEXTOR, CASTOR, T-10 and ISTTOK have provided new and complementary evidence on the physics of the universal mechanism of E x B velocity shear stabilization of turbulence, concomitant transport barrier formation and radial conductivity by using various edge biasing techniques. (orig.)

  14. Tuning the band gap of silicene by functionalisation with naphthyl and anthracyl groups

    Energy Technology Data Exchange (ETDEWEB)

    Brennan, Mathew D.; Spencer, Michelle J. S., E-mail: t-morishita@aist.go.jp, E-mail: michelle.spencer@rmit.edu.au [School of Science, RMIT University, GPO Box 2476, Melbourne, Victoria 3001 (Australia); Morishita, Tetsuya, E-mail: t-morishita@aist.go.jp, E-mail: michelle.spencer@rmit.edu.au [Research Center for Computational Design of Advanced Functional Materials, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

    2016-03-21

    Silicene is a relatively new material consisting of a two-dimensional sheet of silicon atoms. Functionalisation of silicene with different chemical groups has been suggested as a way to tune its electronic properties. In this work, density functional theory calculations and ab initio molecular dynamics simulations are used to examine the effects of functionalisation with naphthyl or anthracyl groups, which are two examples of small polycyclic aromatic hydrocarbons (PAHs). Different attachment positions on the naphthyl and anthracyl groups were compared, as well as different thicknesses of the silicene nanosheet. It was found that the carbon attachment position farthest from the bond fusing the aromatic rings gave the more stable structures for both functional groups. All structures showed direct band gaps, with tuning of the band gap being achievable by increasing the length of the PAH or the thickness of the silicene. Hence, modifying the functional group or thickness of the silicene can both be used to alter the electronic properties of silicene making it a highly promising material for use in future electronic devices and sensors.

  15. Velocities of dislocation groups in very thin neutron-irradiated copper single crystals measured by slip line cinematography

    International Nuclear Information System (INIS)

    Potthoff, H.H.

    1983-01-01

    Slip line development on very thin flat single crystals of neutron-irradiated Cu (thickness down to only 15 to 20 μm, orientation for single glide, yield region, room temperature) is recorded by high-speed cinematography during tensile deformation. In such very thin crystals glide dislocations on the slip plane must be arranged in a rather simple way. Drops in tensile load occuring during initiation of single slip lines at the Lueders band front indicate that in the beginning of a slip line development dislocation groups traverse the whole glide plane in very short times. Evaluating the data measured for the slip line growth v/sub s/ >= 10 cm/s is found for screw dislocations and v/sub e/ >= v/sub s/ for edge dislocations. For later stages on thin crystals and for all stages on thick crystals (>= several 100 μm) slip line development is much slower and slip line show many cross slip events which then appear to control the mean velocity of the dislocations. (author)

  16. Rogue events in the group velocity horizon.

    Science.gov (United States)

    Demircan, Ayhan; Amiranashvili, Shalva; Brée, Carsten; Mahnke, Christoph; Mitschke, Fedor; Steinmeyer, Günter

    2012-01-01

    The concept of rogue waves arises from a mysterious and potentially calamitous phenomenon of oceanic surfaces. There is mounting evidence that they are actually commonplace in a variety of different physical settings. A set of defining criteria has been advanced; this set is of great generality and therefore applicable to a wide class of systems. The question arises naturally whether there are generic mechanisms responsible for extreme events in different systems. Here we argue that under suitable circumstances nonlinear interaction between weak and strong waves results in intermittent giant waves with all the signatures of rogue waves. To obtain these circumstances only a few basic conditions must be met. Then reflection of waves at the so-called group-velocity horizon occurs. The connection between rogue waves and event horizons, seemingly unrelated physical phenomena, is identified as a feature common in many different physical systems.

  17. Coupling X-band dual-polarized mini-radars and hydro-meteorological forecast models: the HYDRORAD project

    Directory of Open Access Journals (Sweden)

    E. Picciotti

    2013-05-01

    Full Text Available Hydro-meteorological hazards like convective outbreaks leading to torrential rain and floods are among the most critical environmental issues world-wide. In that context weather radar observations have proven to be very useful in providing information on the spatial distribution of rainfall that can support early warning of floods. However, quantitative precipitation estimation by radar is subjected to many limitations and uncertainties. The use of dual-polarization at high frequency (i.e. X-band has proven particularly useful for mitigating some of the limitation of operational systems, by exploiting the benefit of easiness to transport and deploy and the high spatial and temporal resolution achievable at small antenna sizes. New developments on X-band dual-polarization technology in recent years have received the interest of scientific and operational communities in these systems. New enterprises are focusing on the advancement of cost-efficient mini-radar network technology, based on high-frequency (mainly X-band and low-power weather radar systems for weather monitoring and hydro-meteorological forecasting. Within the above context, the main objective of the HYDRORAD project was the development of an innovative mbox{integrated} decision support tool for weather monitoring and hydro-meteorological applications. The integrated system tool is based on a polarimetric X-band mini-radar network which is the core of the decision support tool, a novel radar products generator and a hydro-meteorological forecast modelling system that ingests mini-radar rainfall products to forecast precipitation and floods. The radar products generator includes algorithms for attenuation correction, hydrometeor classification, a vertical profile reflectivity correction, a new polarimetric rainfall estimators developed for mini-radar observations, and short-term nowcasting of convective cells. The hydro-meteorological modelling system includes the Mesoscale Model 5

  18. An Improved X-Band Maser System for Deep Space Network Applications

    Science.gov (United States)

    Britcliffe, M.; Hanson, T.; Fernandez, J.

    2000-01-01

    An 8450-MHz (X-band) maser system utilizing a commercial Gifford--McMahon (GM) closed-cycle cryocooler (CCR) was designed, fabricated, and demonstrated. The CCR system was used to cool a maser operating at 8450 MHz. The prototype GM CCR system meets or exceeds all Deep Space Network requirements for maser performance. The two-stage GM CCR operates at 4.2 K; for comparison, the DSN's current three-stage cryocooler, which uses a Joule--Thompson cooling stage in addition to GM cooling, operates at 4.5 K. The new CCR withstands heat loads of 1.5 W at 4.2 K as compared to 1 W at 4.5 K for the existing DSN cryocooler used for cooling masers. The measured noise temperature, T_e, of the maser used for these tests is defined at the ambient connection to the antenna feed system. The T_e measured 5.0 K at a CCR temperature of 4.5 K, about 1.5 K higher than the noise temperature of a typical DSN Block II-A X-band traveling-wave maser (TWM). Reducing the temperature of the CCR significantly lowers the maser noise temperature and increases maser gain and bandwidth. The new GM CCR gives future maser systems significant operational advantages, including reduced maintenance time and logistics requirements. The results of a demonstration of this new system are presented. Advantages of using a GM-cooled maser and the effects of the reduced CCR temperature on maser performance are discussed.

  19. Electron beam and rf characterization of a low-emittance X-band photoinjector

    Directory of Open Access Journals (Sweden)

    D. J. Gibson

    2001-09-01

    Full Text Available Detailed experimental studies of the first operation of an X-band (8.547 GHz rf photoinjector are reported. The rf characteristics of the device are first described, as well as the tuning technique used to ensure operation of the 11/2-cell rf gun in the balanced π-mode. The characterization of the photoelectron beam produced by the rf gun includes: measurements of the bunch charge as a function of the laser injection phase, yielding information about the quantum efficiency of the Cu photocathode ( 2×10^{-5} for a surface field of 100 MV/m; measurements of the beam energy (1.5–2 MeV and relative energy spread ( Δγ/γ_{0}=1.8±0.2% using a magnetic spectrometer; measurements of the beam 90% normalized emittance, which is found to be ɛ_{n}=1.65π mm mrad for a charge of 25 pC; and measurements of the bunch duration ( <2 ps. Coherent synchrotron radiation experiments at Ku-band and Ka-band confirm the extremely short duration of the photoelectron bunch and a peak power scaling quadratically with the bunch charge.

  20. X-ray short-time lags in the Fe-K energy band produced by scattering clouds in active galactic nuclei

    Science.gov (United States)

    Mizumoto, Misaki; Done, Chris; Hagino, Kouichi; Ebisawa, Ken; Tsujimoto, Masahiro; Odaka, Hirokazu

    2018-05-01

    X-rays illuminating the accretion disc in active galactic nuclei give rise to an iron K line and its associated reflection spectrum which are lagged behind the continuum variability by the light-travel time from the source to the disc. The measured lag timescales in the iron band can be as short as ˜Rg/c, where Rg is the gravitational radius, which is often interpreted as evidence for a very small continuum source close to the event horizon of a rapidly spinning black hole. However, the short lags can also be produced by reflection from more distant material, because the primary photons with no time-delay dilute the time-lags caused by the reprocessed photons. We perform a Monte-Carlo simulation to calculate the dilution effect in the X-ray reverberation lags from a half-shell of neutral material placed at 100 Rg from the central source. This gives lags of ˜2 Rg/c, but the iron line is a distinctly narrow feature in the lag-energy plot, whereas the data often show a broader line. We show that both the short lag and the line broadening can be reproduced if the scattering material is outflowing at ˜0.1c. The velocity structure in the wind can also give shifts in the line profile in the lag-energy plot calculated at different frequencies. Hence we propose that the observed broad iron reverberation lags and shifts in profile as a function of frequency of variability can arise from a disc wind at fairly large distances from the X-ray source.

  1. Valence band offset of β-Ga2O3/wurtzite GaN heterostructure measured by X-ray photoelectron spectroscopy.

    Science.gov (United States)

    Wei, Wei; Qin, Zhixin; Fan, Shunfei; Li, Zhiwei; Shi, Kai; Zhu, Qinsheng; Zhang, Guoyi

    2012-10-10

    A sample of the β-Ga2O3/wurtzite GaN heterostructure has been grown by dry thermal oxidation of GaN on a sapphire substrate. X-ray diffraction measurements show that the β-Ga2O3 layer was formed epitaxially on GaN. The valence band offset of the β-Ga2O3/wurtzite GaN heterostructure is measured by X-ray photoelectron spectroscopy. It is demonstrated that the valence band of the β-Ga2O3/GaN structure is 1.40 ± 0.08 eV.

  2. Studies of Shear Band Velocity Using Spatially and Temporally Resolved Measurements of Strain During Quasistatic Compression of Bulk Metallic Glass

    Energy Technology Data Exchange (ETDEWEB)

    Wright, W J; Samale, M; Hufnagel, T; LeBlanc, M; Florando, J

    2009-06-15

    We have made measurements of the temporal and spatial features of the evolution of strain during the serrated flow of Pd{sub 40}Ni{sub 40}P{sub 20} bulk metallic glass tested under quasistatic, room temperature, uniaxial compression. Strain and load data were acquired at rates of up to 400 kHz using strain gages affixed to all four sides of the specimen and a piezoelectric load cell located near the specimen. Calculation of the displacement rate requires an assumption about the nature of the shear displacement. If one assumes that the entire shear plane displaces simultaneously, the displacement rate is approximately 0.002 m/s. If instead one assumes that the displacement occurs as a localized propagating front, the velocity of the front is approximately 2.8 m/s. In either case, the velocity is orders of magnitude less than the shear wave speed ({approx}2000 m/s). The significance of these measurements for estimates of heating in shear bands is discussed.

  3. Wakefield Band Partitioning in LINAC Structures

    International Nuclear Information System (INIS)

    Jones, Roger M

    2003-01-01

    In the NLC project multiple bunches of electrons and positrons will be accelerated initially to a centre of mass of 500 GeV and later to 1 TeV or more. In the process of accelerating 192 bunches within a pulse train, wakefields are excited which kick the trailing bunches off axis and can cause luminosity dilution and BBU (Beam Break Up). Several structures to damp the wakefield have been designed and tested at SLAC and KEK and these have been found to successfully damp the wakefield [1]. However, these 2π/3 structures suffered from electrical breakdown and this has prompted us to explore lower group velocity structures operating at higher fundamental mode phase advances. The wakefield partitioning amongst the bands has been found to change markedly with increased phase advance. Here we report on general trends in the kick factor and associated wakefield band partitioning in dipole bands as a function of phase advance of the synchronous mode in linacs. These results are applicable to both TW (travelling wave) and SW (standing wave) structures

  4. A Novel Low RCS Design Method for X-Band Vivaldi Antenna

    Directory of Open Access Journals (Sweden)

    XiaoXiang He

    2012-01-01

    Full Text Available A novel low radar cross-section (RCS design method is proposed, and its application on Vivaldi antenna that covers the entire X band is investigated. According to the difference of the current distribution on the radiator when the antenna radiates or scatters, the shape of the metal radiator is modified, so that maximally 19.2 dBsm RCS reduction is achieved which satisfied radiation performance. Simulated and measured results about gain, S11, and RCS are presented. As a result, the effectiveness of the presented low RCS design method is validated.

  5. Waves in microstructured solids and negative group velocity

    Science.gov (United States)

    Peets, T.; Kartofelev, D.; Tamm, K.; Engelbrecht, J.

    2013-07-01

    Waves with negative group velocity (NGV) were discovered in optics by Sommerfeld and Brillouin, and experimentally verified in many cases, for example in left-handed media. For waves in solids, such an effect is described mostly in layered media. In this paper, it is demonstrated that in microstructured solids, waves with NGV may also exist leading to backwards pulse propagation. Two physical cases are analysed: a Mindlin-type hierarchical (a scale within a scale) material and a felt-type (made of fibres) material. For both cases, the dispersion analysis of one-dimensional waves shows that there exists certain ranges of physical parameters which lead to NGV. The results can be used in dispersion engineering for designing materials with certain properties.

  6. Conduction mechanism in Polyaniline-flyash composite material for shielding against electromagnetic radiation in X-band & Ku band

    Directory of Open Access Journals (Sweden)

    Avanish Pratap Singh

    2011-06-01

    Full Text Available β–Naphthalene sulphonic acid (β–NSA doped polyaniline (PANI–flyash (FA composites have been prepared by chemical oxidative polymerization route whose conductivity lies in the range 2.37–21.49 S/cm. The temperature dependence of electrical conductivity has also been recorded which shows that composites follow Mott's 3D–VRH model. SEM images demonstrate that β–NSA leads to the formation of the tubular structure with incorporated flyash phase. TGA studies show the improvement in thermal stability of composites with increase in loading level of flyash. Complex parameters i.e. permittivity (ɛ* = ɛ′- iɛ″ and permeability (μ*=μ′- iμ″ of PANI-FA composites have been calculated from experimental scattering parameters (S11 & S21 using theoretical calculations given in Nicholson–Ross and Weir algorithms. The microwave absorption properties of the composites have been studied in X-band (8.2 – 12.4 GHz & Ku–Band (12.4 – 18 GHz frequency range. The maximum shielding effectiveness observed was 32dB, which strongly depends on dielectric loss and volume fraction of flyash in PANI matrix.

  7. Band alignment of TiO2/FTO interface determined by X-ray photoelectron spectroscopy: Effect of annealing

    Directory of Open Access Journals (Sweden)

    Haibo Fan

    2016-01-01

    Full Text Available The energy band alignment between pulsed-laser-deposited TiO2 and FTO was firstly characterized using high-resolution X-ray photoelectron spectroscopy. A valence band offset (VBO of 0.61 eV and a conduction band offset (CBO of 0.29 eV were obtained across the TiO2/FTO heterointerface. With annealing process, the VBO and CBO across the heterointerface were found to be -0.16 eV and 1.06 eV, respectively, with the alignment transforming from type-I to type-II. The difference in the band alignment is believed to be dominated by the core level down-shift of the FTO substrate, which is a result of the oxidation of Sn. Current-voltage test has verified that the band alignment has a significant effect on the current transport of the heterojunction.

  8. Clusters, groups, and filaments in the Chandra deep field-south up to redshift 1

    International Nuclear Information System (INIS)

    Dehghan, S.; Johnston-Hollitt, M.

    2014-01-01

    We present a comprehensive structure detection analysis of the 0.3 deg 2 area of the MUSYC-ACES field, which covers the Chandra Deep Field-South (CDFS). Using a density-based clustering algorithm on the MUSYC and ACES photometric and spectroscopic catalogs, we find 62 overdense regions up to redshifts of 1, including clusters, groups, and filaments. We also present the detection of a relatively small void of ∼10 Mpc 2 at z ∼ 0.53. All structures are confirmed using the DBSCAN method, including the detection of nine structures previously reported in the literature. We present a catalog of all structures present, including their central position, mean redshift, velocity dispersions, and classification based on their morphological and spectroscopic distributions. In particular, we find 13 galaxy clusters and 6 large groups/small clusters. Comparison of these massive structures with published XMM-Newton imaging (where available) shows that 80% of these structures are associated with diffuse, soft-band (0.4-1 keV) X-ray emission, including 90% of all objects classified as clusters. The presence of soft-band X-ray emission in these massive structures (M 200 ≥ 4.9 × 10 13 M ☉ ) provides a strong independent confirmation of our methodology and classification scheme. In the closest two clusters identified (z < 0.13) high-quality optical imaging from the Deep2c field of the Garching-Bonn Deep Survey reveals the cD galaxies and demonstrates that they sit at the center of the detected X-ray emission. Nearly 60% of the clusters, groups, and filaments are detected in the known enhanced density regions of the CDFS at z ≅ 0.13, 0.52, 0.68, and 0.73. Additionally, all of the clusters, bar the most distant, are found in these overdense redshift regions. Many of the clusters and groups exhibit signs of ongoing formation seen in their velocity distributions, position within the detected cosmic web, and in one case through the presence of tidally disrupted central galaxies

  9. Clusters, groups, and filaments in the Chandra deep field-south up to redshift 1

    Energy Technology Data Exchange (ETDEWEB)

    Dehghan, S.; Johnston-Hollitt, M., E-mail: siamak.dehghan@vuw.ac.nz [School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140 (New Zealand)

    2014-03-01

    We present a comprehensive structure detection analysis of the 0.3 deg{sup 2} area of the MUSYC-ACES field, which covers the Chandra Deep Field-South (CDFS). Using a density-based clustering algorithm on the MUSYC and ACES photometric and spectroscopic catalogs, we find 62 overdense regions up to redshifts of 1, including clusters, groups, and filaments. We also present the detection of a relatively small void of ∼10 Mpc{sup 2} at z ∼ 0.53. All structures are confirmed using the DBSCAN method, including the detection of nine structures previously reported in the literature. We present a catalog of all structures present, including their central position, mean redshift, velocity dispersions, and classification based on their morphological and spectroscopic distributions. In particular, we find 13 galaxy clusters and 6 large groups/small clusters. Comparison of these massive structures with published XMM-Newton imaging (where available) shows that 80% of these structures are associated with diffuse, soft-band (0.4-1 keV) X-ray emission, including 90% of all objects classified as clusters. The presence of soft-band X-ray emission in these massive structures (M {sub 200} ≥ 4.9 × 10{sup 13} M {sub ☉}) provides a strong independent confirmation of our methodology and classification scheme. In the closest two clusters identified (z < 0.13) high-quality optical imaging from the Deep2c field of the Garching-Bonn Deep Survey reveals the cD galaxies and demonstrates that they sit at the center of the detected X-ray emission. Nearly 60% of the clusters, groups, and filaments are detected in the known enhanced density regions of the CDFS at z ≅ 0.13, 0.52, 0.68, and 0.73. Additionally, all of the clusters, bar the most distant, are found in these overdense redshift regions. Many of the clusters and groups exhibit signs of ongoing formation seen in their velocity distributions, position within the detected cosmic web, and in one case through the presence of tidally

  10. Mapping Changes and Damages in Areas of Conflict: From Archive C-Band SAR Data to New HR X-Band Imagery, Towards the Sentinels

    Science.gov (United States)

    Tapete, Deodato; Cigna, Francesca; Donoghue, Daniel N. M.; Philip, Graham

    2015-05-01

    On the turn of radar space science with the recent launch of Sentinel-1A, we investigate how to better exploit the opportunities offered by large C-band SAR archives and increasing datasets of HR to VHR X-band data, to map changes and damages in urban and rural areas affected by conflicts. We implement a dual approach coupling multi-interferogram processing and amplitude change detection, to assess the impact of the recent civil war on the city of Homs, Western Syria, and the surrounding semi-arid landscape. More than 280,000 coherent pixels are retrieved from Small BAseline Subset (SBAS) processing of the 8year-long ENVISAT ASAR IS2 archive, to quantify land subsidence due to pre-war water abstraction in rural areas. Damages in Homs are detected by analysing the changes of SAR backscattering (σ0), comparing 3m-resolution StripMap TerraSAR-X pairs from 2009 to 2014. Pre-war alteration is differentiated from war-related damages via operator-driven interpretation of the σ0 patterns.

  11. X-Band wave radar system for monitoring and risk management of the coastal infrastructures

    Science.gov (United States)

    Ludeno, Giovanni; Soldovieri, Francesco; Serafino, Francesco

    2017-04-01

    The presence of the infrastructures in coastal region entails an increase of the sea level and the shift of the sediment on the bottom with a continuous change of the coastline. In order to preserve the coastline, it has been necessary to resort the use of applications coastal engineering, as the construction of the breakwaters for preventing the coastal erosion. In this frame, the knowledge of the sea state parameters, as wavelength, period and significant wave height and of surface current and bathymetry can be used for the harbor operations and to prevent environmental disasters. In the last years, the study of the coastal phenomena and monitoring of the sea waves impact on the coastal infrastructures through the analysis of images acquired by marine X-band radars is of great interest [1-3]. The possibility to observe the sea surface from radar images is due to the fact that the X-band electromagnetic waves interact with the sea capillary waves (Bragg resonance), which ride on the gravity waves. However, the image acquired by a X-band radar is not the direct representation of the sea state, but it represents the sea surface as seen by the radar. Accordingly, to estimate the sea state parameters as, direction, wavelength, period of dominant waves, the significant wave height as well as the bathymetry and surface current, through a time stack of radar data are required advanced data processing procedures. In particular, in the coastal areas due to the non-uniformity of sea surface current and bathymetry fields is necessary a local analysis of the sea state parameters. In order to analyze the data acquired in coastal area an inversion procedure defined "Local Method" is adopted, which is based on the spatial partitioning of the investigated area in partially overlapping sub-areas. In addition, the analysis of the sea spectrum of each sub-area allows us to retrieve the local sea state parameters. In particular, this local analysis allows us to detect the reflected

  12. Mesoscale kinematics derived from X-band Doppler radar observations of convective versus stratiform precipitation and comparison with GPS radiosonde profiles

    Science.gov (United States)

    Deshpande, Sachin M.; Dhangar, N.; Das, S. K.; Kalapureddy, M. C. R.; Chakravarty, K.; Sonbawne, S.; Konwar, M.

    2015-11-01

    Single Doppler analysis techniques known as velocity azimuth display (VAD) and volume velocity processing (VVP) are used to analyze kinematics of mesoscale flow such as horizontal wind and divergence using X-band Doppler weather radar observations, for selected cases of convective, stratiform, and shallow cloud systems near tropical Indian sites Pune (18.58°N, 73.92°E, above sea level (asl) 560 m) and Mandhardev (18.51°N, 73.85°E, asl 1297 m). The vertical profiles of horizontal wind estimated from radar VVP/VAD methods agree well with GPS radiosonde profiles, with the low-level jet at about 1.5 km during monsoon season well depicted in both. The vertical structure and temporal variability of divergence and reflectivity profiles are indicative of the dynamical and microphysical characteristics of shallow convective, deep convective, and stratiform cloud systems. In shallow convective systems, vertical development of reflectivity profiles is limited below 5 km. In deep convective systems, reflectivity values as large as 55 dBZ were observed above freezing level. The stratiform system shows the presence of a reflectivity bright band (~35 dBZ) near the melting level. The diagnosed vertical profiles of divergence in convective and stratiform systems are distinct. In shallow convective conditions, convergence was seen below 4 km with divergence above. Low-level convergence and upper level divergence are observed in deep convective profiles, while stratiform precipitation has midlevel convergence present between lower level and upper level divergence. The divergence profiles in stratiform precipitation exhibit intense shallow layers of "melting convergence" at 0°C level, near 4.5 km altitude, with a steep gradient on the both sides of the peak. The level of nondivergence in stratiform situations is lower than that in convective situations. These observed vertical structures of divergence are largely indicative of latent heating profiles in the atmosphere, an

  13. SLAC RF Source Research at X-Band

    International Nuclear Information System (INIS)

    Sprehn, D.

    2003-01-01

    X-band klystrons capable of 75 MW and utilizing either solenoidal or Periodic Permanent Magnet (PPM) focusing are undergoing design, fabrication and testing at the Stanford Linear Accelerator Center (SLAC). The klystron development is part of an effort to realize components necessary for the construction of the Next Linear Collider (NLC). SLAC has developed a solenoidal-focused X-band klystron which is currently the workhorse of high power component testing for the NLC. A state-of-the-art modulator will drive eight of these tubes which, in turn, will power an rf distribution system referred to as the ''8-pack'' in order to test these modulators and waveguide components. Eventually, in an interest to save millions of dollars per year in the operational cost of the NLC, these tubes will be replaced by PPM klystrons. The PPM devices built to date which fit this class of operation consist of a variety of 50 MW and 75 MW devices constructed by SLAC, KEK (Tsukuba, Japan ), and industry. These tubes follow from the successful 50 MW PPM design of 1996. Recent testing of this particular tube at wider pulsewidths has reached 50 MW at 55 % efficiency, 2.4 μs and 60 Hz. Two 50 MW PPM klystrons produced by industry have been delivered to SLAC. One of these devices arrived with a vacuum suitable for test. Testing during 2001 revealed a serious, but curious, vacuum response which limited the operation to an rf output of ∼40 MW. A 75 MW PPM klystron prototype was first constructed in 1997 and later modified in 1999 to eliminate oscillations. This tube has reached the NLC design target of 75 MW at 1.5 μs though at a significantly reduced rep rate. Two new 75 MW PPM klystrons were constructed and tested in 2002 after a diode was successfully tested in 2001. The new design was aimed at reducing the cost and increasing the reliability of such high-energy devices. The rf circuit and beam focusing for one of these devices was built by industry and incorporated into one of the tubes

  14. A Space View of Radar Archaeological Marks: First Applications of COSMO-SkyMed X-Band Data

    Directory of Open Access Journals (Sweden)

    Fulong Chen

    2014-12-01

    Full Text Available With the development of Synthetic Aperture Radar (SAR in terms of multi-band, multi-polarization and high-resolution data, space radar remote sensing for archaeology has become a potential field for research. Nevertheless, the archaeological detection capability of this technology has so far not been fully assessed. This paper is a pioneering effort to assess the potential of satellite SAR X-band data in the detection of archaeological marks. We focus on the results obtained from a collaborative contribution jointly carried out by archaeologists and remote sensing experts in order to test the use of COSMO-SkyMed data in different contexts and environmental conditions. The methodological approaches we adopted are based on two different feature-enhancement procedures: (i multi-temporal analysis performed to reduce noise and highlight archaeological marks; (ii single-date analysis to assess the ability of the single SAR scene to detect archaeological features like with optical remote sensing. Results from multi-temporal data analysis, conducted using 40 scenes from COSMO-SkyMed X-band Stripmap data (27 February to 17 October 2013, enable us to detect unknown archaeological crop, soil, and shadow marks representing Luoyang city, dating from the Eastern-Han to Northern-Wei Dynasties. Single-date analyses were conducted using COSMO-SkyMed Spotlight scenes acquired for Sabratha (Libya and Metapontum (southern Italy. These case studies were selected because they are characterized by diverse superficial conditions (desert and Mediterranean area and archaeological marks (crop, soil and shadow. The results we obtained for both of them show that even a single SAR X-band acquisition is a feasible and effective approach for archaeological prospection. Overall, the methodological approach adopted demonstrated that both multi-temporal and single-date analysis are suitable for the enhancement of archaeological and palaeoenvironmental features.

  15. A Solar-Pumped Fluorescence Model for Line-By-Line Emission Intensities in the B-X, A-X, and X-X Band Systems of 12C14N

    Science.gov (United States)

    Paganini, L.; Mumma, M. J.

    2016-01-01

    We present a new quantitative model for detailed solar-pumped fluorescent emission of the main isotopologue of CN. The derived fluorescence efficiencies permit estimation and interpretation of ro-vibrational infrared line intensities of CN in exospheres exposed to solar (or stellar) radiation. Our g-factors are applicable to astronomical observations of CN extending from infrared to optical wavelengths, and we compare them with previous calculations in the literature. The new model enables extraction of rotational temperature, column abundance, and production rate from astronomical observations of CN in the inner coma of comets. Our model accounts for excitation and de-excitation of rotational levels in the ground vibrational state by collisions, solar excitation to the A(sup 2)Pi(sub I) and B(sup 2)Sum(sup +) electronically excited states followed by cascade to ro-vibrational levels of X(sup 2)Sum(sup +), and direct solar infrared pumping of ro-vibrational levels in the X(sup 2)Sum(sup +) state. The model uses advanced solar spectra acquired at high spectral resolution at the relevant infrared and optical wavelengths and considers the heliocentric radial velocity of the comet (the Swings effect) when assessing the exciting solar flux for a given transition. We present model predictions for the variation of fluorescence rates with rotational temperature and heliocentric radial velocity. Furthermore, we test our fluorescence model by comparing predicted and measured line-by-line intensities for X(sup 2)Sum(sup +) (1-0) in comet C/2014 Q2 (Lovejoy), thereby identifying multiple emission lines observed at IR wavelengths.

  16. The study on cytogenetic analysis and dosimetry reconstruction for medical diagnostic X-ray workers using G-banding and fluorescence in situ hybridization

    International Nuclear Information System (INIS)

    Li Jin; Wang Qin; Tang Weisheng; Sun Yuanming; Wang Zhiquan

    2003-01-01

    Objective: To estimate the dose of medical diagnostic X-ray workers. Methods: The chromosome aberrations were analyzed by G-banding or FISH in medical diagnostic X-ray workers with different calendar years of entry. Results: The biological doses estimated by the two methods were in agreement with the doses evaluated by physical methods. Conclusion: G-banding and FISH are effective ways to analyse the chromosome translocations

  17. Design of a 100 MW X-band klystron

    International Nuclear Information System (INIS)

    Eppley, K.

    1989-02-01

    Future linear colliders will require klystrons with higher peak power at higher frequency than are currently in use. SLAC is currently designing a 100 MW klystron at 11.4 GHz as a prototype for such a tube. The gun has been designed for 440 KV and 510 amps. Transporting this beam through a 5 mm radius X-band drift tube presents the major design problem. The area convergence ratio of 190 to one is over ten times higher than is found in conventional klystrons. Even with high magnetic fields of 6 to 7 kilogauss careful matching is required to prevent excessive scalloping. Extensive EGUN and CONDOR simulations have been made to optimize the transmission and rf efficiency. The EGUN simulations indicate that better matching is possible by using resonant magnetic focusing. CONDOR calculations indicate efficiencies of 45 percent are possible with a double output cavity. We will discuss the results of the simulations and the status of the experimental program. 3 refs., 6 figs., 2 tabs

  18. Design of a 100 MW X-band klystron

    Science.gov (United States)

    Eppley, Kenneth

    1989-02-01

    Future linear colliders will require klystrons with higher peak power at higher frequency than are currently in use. SLAC is currently designing a 100 MW klystron at 11.4 GHz as a prototype for such a tube. The gun has been designed for 440 kV and 510 amps. Transporting this beam through a 5 mm radius X-band drift tube presents the major design problem. The area convergence ratio of 190 to one is over ten times higher than is found in conventional klystrons. Even with high magnetic fields of 6 to 7 kilogauss careful matching is required to prevent excessive scalloping. Extensive EGUN and CONDOR simulations have been made to optimize the transmission and RF efficiency. The EGUN simulations indicate that better matching is possible by using resonant magnetic focusing. CONDOR calculations indicate efficiencies of 45 percent are possible with a double output cavity. We will discuss the results of the simulations and the status of the experimental program.

  19. Development of X-band klystron technology at SLAC

    International Nuclear Information System (INIS)

    Caryotakis, G.

    1997-05-01

    The SLAC design for a 1-TeV collider (NLC) requires klystrons with a performance which is well beyond the state-of-the-art for microwave tubes in the United States or abroad. The electrical specifications for the NLC klystrons are not fully established, but they are approximately as follows: Frequency, 11.4 GHz; Peak Power, 75 MW; Pulse Length, 1.5 μs; Repetition Rate, 180 Hz; Gain, 50 dB; Efficiency, (including beam focusing) 50%. SLAC is in the seventh year of a program to develop these klystrons. The choice of X-band as the operating frequency, along with the sheer size of the NLC, have resulted in some new, most demanding standards for the klystrons which may power this future machine. These are related to the overall efficiency required, to the high rf gradients that must be supported at the output circuit without vacuum breakdown, and to the manufacturing cost of the 5,000-10,000 klystrons needed for the collider

  20. The electronic band parameters calculated by the Kronig-Penney method for Cd1-xZnxS quantum dot superlattices

    International Nuclear Information System (INIS)

    Sakly, A.; Safta, N.; Mejri, H.; Lamine, A. Ben

    2009-01-01

    This work reports on a theoretical study of superlattices based on Cd 1-x Zn x S quantum dots embedded in an insulating material. We show, in particular, how this system can be assumed to a series of flattened cylindrical quantum dots with a finite barrier height at the boundary. In this paper, are also reviewed the approximations needed to calculate the band edges of the Cd 1-x Zn x S superlattices with use of the Kronig-Penney model. The electronic states and the electron effective masses of both Γ 1 - and Γ 2 -minibands have been computed as a function of zinc composition for different inter-quantum dot separations. As is found, the CdS system is appropriate to give rise a superlattice behavior for conduction electrons in a relatively large range of inter-sheet separations. An attempt to explain the electron band parameters calculated will be presented.

  1. Characteristics of light reflected from a dense ionization wave with a tunable velocity.

    Science.gov (United States)

    Zhidkov, A; Esirkepov, T; Fujii, T; Nemoto, K; Koga, J; Bulanov, S V

    2009-11-20

    An optically dense ionization wave (IW) produced by two femtosecond (approximately 10/30 fs) laser pulses focused cylindrically and crossing each other may become an efficient coherent x-ray converter in accordance with the Semenova-Lampe theory. The resulting velocity of a quasiplane IW in the vicinity of pulse intersection changes with the angle between the pulses from the group velocity of ionizing pulses to infinity allowing a tuning of the wavelength of x rays and their bunching. The x-ray spectra after scattering of a lower frequency and long coherent light pulse change from the monochromatic to high order harmoniclike with the duration of the ionizing pulses.

  2. Diastolic coronary artery pressure-flow velocity relationships in conscious man.

    Science.gov (United States)

    Dole, W P; Richards, K L; Hartley, C J; Alexander, G M; Campbell, A B; Bishop, V S

    1984-09-01

    We characterised the diastolic pressure-flow velocity relationship in the normal left coronary artery of conscious man before and after vasodilatation with angiographic contrast medium. Phasic coronary artery pressure and flow velocity were measured in ten patients during individual diastoles (0.5 to 1.0 s) using a 20 MHz catheter-tipped, pulsed Doppler transducer. All pressure-flow velocity curves were linear over the diastolic pressure range of 110 +/- 15 (SD) mmHg to 71 +/- 7 mmHg (r = 0.97 +/- 0.01). In the basal state, values for slope and extrapolated zero flow pressure intercept averaged 0.35 +/- 0.12 cm X s-1 X mmHg-1 and 51.7 +/- 8.6 mmHg, respectively. Vasodilatation resulted in a 2.5 +/- 0.5 fold increase in mean flow velocity. The diastolic pressure-flow velocity relationship obtained during peak vasodilatation compared to that during basal conditions was characterised by a steeper slope (0.80 +/- 0.48 cm X s-1 X mmHg-1, p less than 0.001) and lower extrapolated zero flow pressure intercept (37.9 +/- 9.8 mmHg, p less than 0.05). Mean right atrial pressure for the group averaged 4.4 +/- 1.7 mmHg, while left ventricular end-diastolic pressure averaged 8.7 +/- 2.8 mmHg. These observations in man are similar to data reported in the canine coronary circulation which are consistent with a vascular waterfall model of diastolic flow regulation. In this model, coronary blood flow may be regulated by changes in diastolic zero flow pressure as well as in coronary resistance.

  3. The impact of different multi-walled carbon nanotubes on the X-band microwave absorption of their epoxy nanocomposites.

    Science.gov (United States)

    Che, Bien Dong; Nguyen, Bao Quoc; Nguyen, Le-Thu T; Nguyen, Ha Tran; Nguyen, Viet Quoc; Van Le, Thang; Nguyen, Nieu Huu

    2015-01-01

    Carbon nanotube (CNT) characteristics, besides the processing conditions, can change significantly the microwave absorption behavior of CNT/polymer composites. In this study, we investigated the influence of three commercial multi-walled CNT materials with various diameters and length-to-diameter aspect ratios on the X-band microwave absorption of epoxy nanocomposites with CNT contents from 0.125 to 2 wt%, prepared by two dispersion methods, i.e. in solution with surfactant-aiding and via ball-milling. The laser diffraction particle size and TEM analysis showed that both methods produced good dispersions at the microscopic level of CNTs. Both a high aspect ratio resulting in nanotube alignment trend and good infiltration of the matrix in the individual nanotubes, which was indicated by high Brookfield viscosities at low CNT contents of CNT/epoxy dispersions, are important factors to achieve composites with high microwave absorption characteristics. The multi-walled carbon nanotube (MWCNT) with the largest aspect ratio resulted in composites with the best X-band microwave absorption performance, which is considerably better than that of reported pristine CNT/polymer composites with similar or lower thicknesses and CNT loadings below 4 wt%. A high aspect ratio of CNTs resulting in microscopic alignment trend of nanotubes as well as a good level of micro-scale CNT dispersion resulting from good CNT-matrix interactions are crucial to obtain effective microwave absorption performance. This study demonstrated that effective radar absorbing MWCNT/epoxy nanocomposites having small matching thicknesses of 2-3 mm and very low filler contents of 0.25-0.5 wt%, with microwave energy absorption in the X-band region above 90% and maximum absorption peak values above 97%, could be obtained via simple processing methods, which is promising for mass production in industrial applications. Graphical AbstractComparison of the X-band microwave reflection loss of epoxy composites of

  4. Design studies of the Ku-band, wide-band Gyro-TWT amplifier

    Science.gov (United States)

    Jung, Sang Wook; Lee, Han Seul; Jang, Kwong Ho; Choi, Jin Joo; Hong, Yong Jun; Shin, Jin Woo; So, Jun Ho; Won, Jong Hyo

    2014-02-01

    This paper reports a Ku-band, wide band Gyrotron-Traveling-wave-tube(Gyro-TWT) that is currently being developed at Kwangwoon University. The Gyro-TWT has a two stage linear tapered interaction circuit to obtain a wide operating bandwidth. The linearly-tapered interaction circuit and nonlinearly-tapered magnetic field gives the Gyro-TWT a wide operating bandwidth. The Gyro-TWT bandwidth is 23%. The 2d-Particle-in-cell(PIC) and MAGIC2d code simulation results are 17.3 dB and 24.34 kW, respectively for the maximum saturated output power. A double anode MIG was simulated with E-Gun code. The results were 0.7 for the transvers to the axial beam velocity ratio (=alpha) and a 2.3% axial velocity spread at 50 kV and 4 A. A magnetic field profile simulation was performed by using the Poisson code to obtain the grazing magnetic field of the entire interaction circuit with Poisson code.

  5. An X- and Q-band Fe{sup 3+} EPR study of nanoparticles of magnetic semiconductor Zn{sub 1−x}Fe{sub x}O

    Energy Technology Data Exchange (ETDEWEB)

    Misra, Sushil K., E-mail: skmisra@alcor.concordia.ca [Physics Department, Concordia University, Montreal, QC, Canada H3G 1M8 (Canada); Andronenko, S.I. [Physics Institute, Kazan Federal University, Kazan 420008 (Russian Federation); Thurber, A.; Punnoose, A. [Department of Physics, Boise State University, Boise, ID 83725-1570 (United States); Nalepa, A. [Max-Planck-Institut für Chemische Energie Konversion, Stifstrasse 34-36, 45470 Mülheim an der Ruhr (Germany)

    2014-08-01

    EPR studies on two types of nanoparticles of Fe{sup 3+} doped, 0.1–10%, ZnO, NL and QJ, prepared using similar chemical hydrolysis methods, in diethylene glycol, and in denatured ethanol solutions, respectively, were carried out at X-band (∼9.5 GHz) at 77 K and at Q-band (∼34.0 GHz) at 10, 80, and 295 K. To interpret the experimental results, EPR spectra were simulated by exact diagonalization of the spin-Hamiltonian matrix to identify the Fe ions at different magnetically active sites in these samples. The simulation for NL samples revealed that they contained (i) Fe{sup 3+} ions, which substituted for Zn ions, the zero-field splitting (ZFS) parameter which has a large distribution over the sample due to oxygen vacancies in the second coordination sphere; (ii) EPR signal from surface oxygen defects; and (iii) ferromagnetically (FM) coupled Fe ions with concentration of Fe more than 1%. The EPR spectra for QJ samples are very different from those for NL samples, exhibiting only rather intense FM EPR lines. The FM and EPR spectra in NL and/or QJ samples are found to vary strongly with differences in the surface morphology of nanoparticles. - Highlights: • X and Q band EPR studies on NL and QJ nanoparticles of Fe{sup 3+} doped ZnO at 10, 80, and 295 K. • Fe ions are present at different magnetically active sites in these samples. • NL samples consist of paramagnetic Fe{sup 3+} ions, and ferromagnetically coupled Fe ions. • QJ samples exhibit only intense ferromagnetic lines, different from QJ. • Spectra vary strongly with the surface morphology of nanoparticles.

  6. Performance limiting effects in X-band accelerators

    Directory of Open Access Journals (Sweden)

    Faya Wang

    2011-01-01

    Full Text Available Acceleration gradient is a critical parameter for the design of future TeV-scale linear colliders. The major obstacle to higher gradient in room-temperature accelerators is rf breakdown, which is still a very mysterious phenomenon that depends on the geometry and material of the accelerator as well as the input power and operating frequency. Pulsed heating has been associated with breakdown for many years; however, there have been no experiments that clearly separate field and heating effects on the breakdown rate. Recently, such experiments have been performed at SLAC with both standing-wave and traveling-wave structures. These experiments have demonstrated that pulsed heating is limiting the gradient. Nevertheless the X-band structures breakdown studies show damage to the iris surfaces in locations of high electric field rather than of high magnetic field after thousands of breakdowns. It is not yet clear how the relative roles of electric field, magnetic field, and heating factor into the damage caused by rf breakdown. Thus, a dual-moded cavity has been designed to better study the electric field, magnetic field, and pulsed heating effects on breakdown damage.

  7. Tomographic Rayleigh wave group velocities in the Central Valley, California, centered on the Sacramento/San Joaquin Delta

    Science.gov (United States)

    Fletcher, Jon B.; Erdem, Jemile; Seats, Kevin; Lawrence, Jesse

    2016-04-01

    If shaking from a local or regional earthquake in the San Francisco Bay region were to rupture levees in the Sacramento/San Joaquin Delta, then brackish water from San Francisco Bay would contaminate the water in the Delta: the source of freshwater for about half of California. As a prelude to a full shear-wave velocity model that can be used in computer simulations and further seismic hazard analysis, we report on the use of ambient noise tomography to build a fundamental mode, Rayleigh wave group velocity model for the region around the Sacramento/San Joaquin Delta in the western Central Valley, California. Recordings from the vertical component of about 31 stations were processed to compute the spatial distribution of Rayleigh wave group velocities. Complex coherency between pairs of stations was stacked over 8 months to more than a year. Dispersion curves were determined from 4 to about 18 s. We calculated average group velocities for each period and inverted for deviations from the average for a matrix of cells that covered the study area. Smoothing using the first difference is applied. Cells of the model were about 5.6 km in either dimension. Checkerboard tests of resolution, which are dependent on station density, suggest that the resolving ability of the array is reasonably good within the middle of the array with resolution between 0.2 and 0.4°. Overall, low velocities in the middle of each image reflect the deeper sedimentary syncline in the Central Valley. In detail, the model shows several centers of low velocity that may be associated with gross geologic features such as faulting along the western margin of the Central Valley, oil and gas reservoirs, and large crosscutting features like the Stockton arch. At shorter periods around 5.5 s, the model's western boundary between low and high velocities closely follows regional fault geometry and the edge of a residual isostatic gravity low. In the eastern part of the valley, the boundaries of the low-velocity

  8. Tomographic Rayleigh-wave group velocities in the Central Valley, California centered on the Sacramento/San Joaquin Delta

    Science.gov (United States)

    Fletcher, Jon Peter B.; Erdem, Jemile; Seats, Kevin; Lawrence, Jesse

    2016-01-01

    If shaking from a local or regional earthquake in the San Francisco Bay region were to rupture levees in the Sacramento/San Joaquin Delta then brackish water from San Francisco Bay would contaminate the water in the Delta: the source of fresh water for about half of California. As a prelude to a full shear-wave velocity model that can be used in computer simulations and further seismic hazard analysis, we report on the use of ambient noise tomography to build a fundamental-mode, Rayleigh-wave group velocity model for the region around the Sacramento/San Joaquin Delta in the western Central Valley, California. Recordings from the vertical component of about 31 stations were processed to compute the spatial distribution of Rayleigh wave group velocities. Complex coherency between pairs of stations were stacked over 8 months to more than a year. Dispersion curves were determined from 4 to about 18 seconds. We calculated average group velocities for each period and inverted for deviations from the average for a matrix of cells that covered the study area. Smoothing using the first difference is applied. Cells of the model were about 5.6 km in either dimension. Checkerboard tests of resolution, which is dependent on station density, suggest that the resolving ability of the array is reasonably good within the middle of the array with resolution between 0.2 and 0.4 degrees. Overall, low velocities in the middle of each image reflect the deeper sedimentary syncline in the Central Valley. In detail, the model shows several centers of low velocity that may be associated with gross geologic features such as faulting along the western margin of the Central Valley, oil and gas reservoirs, and large cross cutting features like the Stockton arch. At shorter periods around 5.5s, the model’s western boundary between low and high velocities closely follows regional fault geometry and the edge of a residual isostatic gravity low. In the eastern part of the valley, the boundaries

  9. Broad-Band Spectroscopy of Hercules X-1 with Suzaku

    Science.gov (United States)

    Asami, Fumi; Enoto, Teruaki; Iwakiri, Wataru; Yamada, Shin'ya; Tamagawa, Toru; Mihara, Tatehiro; Nagase, Fumiaki

    2014-01-01

    Hercules X-1 was observed with Suzaku in the main-on state from 2005 to 2010. The 0.4- 100 keV wide-band spectra obtained in four observations showed a broad hump around 4-9 keV in addition to narrow Fe lines at 6.4 and 6.7 keV. The hump was seen in all the four observations regardless of the selection of the continuum models. Thus it is considered a stable and intrinsic spectral feature in Her X-1. The broad hump lacked a sharp structure like an absorption edge. Thus it was represented by two different spectral models: an ionized partial covering or an additional broad line at 6.5 keV. The former required a persistently existing ionized absorber, whose origin was unclear. In the latter case, the Gaussian fitting of the 6.5-keV line needs a large width of sigma = 1.0-1.5 keV and a large equivalent width of 400-900 eV. If the broad line originates from Fe fluorescence of accreting matter, its large width may be explained by the Doppler broadening in the accretion flow. However, the large equivalent width may be inconsistent with a simple accretion geometry.

  10. The low-lying quartet electronic states of group 14 diatomic borides XB (X = C, Si, Ge, Sn, Pb)

    Science.gov (United States)

    Pontes, Marcelo A. P.; de Oliveira, Marcos H.; Fernandes, Gabriel F. S.; Da Motta Neto, Joaquim D.; Ferrão, Luiz F. A.; Machado, Francisco B. C.

    2018-04-01

    The present work focuses in the characterization of the low-lying quartet electronic and spin-orbit states of diatomic borides XB, in which X is an element of group 14 (C, Si, Ge, Sn, PB). The wavefunction was obtained at the CASSCF/MRCI level with a quintuple-ζ quality basis set. Scalar relativistic effects were also taken into account. A systematic and comparative analysis of the spectroscopic properties for the title molecular series was carried out, showing that the (1)4Π→X4Σ- transition band is expected to be measurable by emission spectroscopy to the GeB, SnB and PbB molecules, as already observed for the lighter CB and SiB species.

  11. Band alignment of TiO{sub 2}/FTO interface determined by X-ray photoelectron spectroscopy: Effect of annealing

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Haibo, E-mail: hbfan@nwu.edu.cn, E-mail: liusz@snnu.edu.cn [Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710119 (China); School of Physics, Northwest University, Xi’an 710069 (China); Yang, Zhou; Ren, Xianpei; Gao, Fei [Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710119 (China); Yin, Mingli [Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710119 (China); School of Science, Xi’an Technological University, Xi’an, Shaanxi 710062 (China); Liu, Shengzhong, E-mail: hbfan@nwu.edu.cn, E-mail: liusz@snnu.edu.cn [Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710119 (China); Dalian Institute of Chemical Physics, Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian, 116023 (China)

    2016-01-15

    The energy band alignment between pulsed-laser-deposited TiO{sub 2} and FTO was firstly characterized using high-resolution X-ray photoelectron spectroscopy. A valence band offset (VBO) of 0.61 eV and a conduction band offset (CBO) of 0.29 eV were obtained across the TiO{sub 2}/FTO heterointerface. With annealing process, the VBO and CBO across the heterointerface were found to be -0.16 eV and 1.06 eV, respectively, with the alignment transforming from type-I to type-II. The difference in the band alignment is believed to be dominated by the core level down-shift of the FTO substrate, which is a result of the oxidation of Sn. Current-voltage test has verified that the band alignment has a significant effect on the current transport of the heterojunction.

  12. Physical properties and band structure of reactive molecular beam epitaxy grown oxygen engineered HfO{sub 2{+-}x}

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrandt, Erwin; Kurian, Jose; Alff, Lambert [Institute of Materials Science, Technische Universitaet Darmstadt, 64287 Darmstadt (Germany)

    2012-12-01

    We have conducted a detailed thin film growth structure of oxygen engineered monoclinic HfO{sub 2{+-}x} grown by reactive molecular beam epitaxy. The oxidation conditions induce a switching between (111) and (002) texture of hafnium oxide. The band gap of oxygen deficient hafnia decreases with increasing amount of oxygen vacancies by more than 1 eV. For high oxygen vacancy concentrations, defect bands form inside the band gap that induce optical transitions and p-type conductivity. The resistivity changes by several orders of magnitude as a function of oxidation conditions. Oxygen vacancies do not give rise to ferromagnetic behavior.

  13. Modeling and design of an X-band rf photoinjector

    Directory of Open Access Journals (Sweden)

    R. A. Marsh

    2012-10-01

    Full Text Available A design for an X-band rf photoinjector that was developed jointly by SLAC National Accelerator Laboratory (SLAC and Lawrence Livermore National Laboratory (LLNL is presented. The photoinjector is based around a 5.59 cell rf gun that has state-of-the-art features including: elliptical contoured irises; improved mode separation; an optimized initial half cell length; a racetrack input coupler; and coupling that balances pulsed heating with cavity fill time. Radio-frequency and beam dynamics modeling have been done using a combination of codes including PARMELA, HFSS, IMPACT-T, ASTRA, and the ACE3P suite of codes developed at SLAC. The impact of lower gradient operation, magnet misalignment, solenoid multipole errors, beam offset, mode beating, wakefields, and beam line symmetry have been analyzed and are described. Fabrication and testing plans at both LLNL and SLAC are discussed.

  14. Effects of electron beam parameters and velocity spread on radio frequency output of a photonic band gap cavity gyrotron oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ashutosh, E-mail: asingh.rs.ece@iitbhu.ac.in [Faculty of Physical Sciences, Institute of Natural Sciences and Humanities, Shri Ramswaroop Memorial University, Lucknow-Deva Road, Uttar Pradesh 225003 (India); Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Jain, P. K. [Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

    2015-09-15

    In this paper, the effects of electron beam parameters and velocity spread on the RF behavior of a metallic photonic band gap (PBG) cavity gyrotron operating at 35 GHz with TE{sub 041}–like mode have been theoretically demonstrated. PBG cavity is used here to achieve a single mode operation of the overmoded cavity. The nonlinear time-dependent multimode analysis has been used to observe the beam-wave interaction behavior of the PBG cavity gyrotron, and a commercially available PIC code “CST Particle Studio” has been reconfigured to obtain 3D simulation results in order to validate the analytical values. The output power for this typical PBG gyrotron has been obtained ∼108 kW with ∼15.5% efficiency in a well confined TE{sub 041}–like mode, while all other competing modes have significantly low values of power output. The output power and efficiency of a gyrotron depend highly on the electron beam parameters and velocity spread. The influence of several electron beam parameters, e.g., beam voltage, beam current, beam velocity pitch factor, and DC magnetic field, on the PBG gyrotron operations has been investigated. This study would be helpful in optimising the electron beam parameters and estimating accurate RF output power of the high frequency PBG cavity based gyrotron oscillators.

  15. Beam Dynamics a Integrated Plane Wave Transformer Photoinjector at S- and X- band

    Science.gov (United States)

    Rosenzweig, J. B.; Ding, X.; Pellegrini, X.; Serafini, L.; Yu, D.

    1997-05-01

    The beam dynamics of an integrated S-band rf photoinjector based on the plane wave transformer concept, proposed as part of an SBIR collaboration between UCLA and DULY Research, are studied. The intial design, which calls for an 11.5 cell structure run at a peak on-axis accelerating field of 60 MV/m, and has a compact solenoid around the intial 2.5 cells, is based on the recently developed theory of emittance compensation(L.Serafini, and J.B. Rosenzweig, submitted to Physical Review E.). It calls for matching the beam onto an envelope which is a generalized Brillouin flow, producing a beam which diminishes in transverse size as the square root of the accelerating beam energy. This condition produces a minimized emittance, which for the S-band case is 1 mm-rad at at charge of 1 nC. This design is also scaled to produce nearly identical performance at X-band, giving an injector appropriate to running an FEL at the SLAC NLCTA. It is noted that these designs are insensitive to rf emittance increase, allowign a choice of injection phase, and the option to compress the emitted pulse.

  16. An Algorithm for Surface Current Retrieval from X-band Marine Radar Images

    Directory of Open Access Journals (Sweden)

    Chengxi Shen

    2015-06-01

    Full Text Available In this paper, a novel current inversion algorithm from X-band marine radar images is proposed. The routine, for which deep water is assumed, begins with 3-D FFT of the radar image sequence, followed by the extraction of the dispersion shell from the 3-D image spectrum. Next, the dispersion shell is converted to a polar current shell (PCS using a polar coordinate transformation. After removing outliers along each radial direction of the PCS, a robust sinusoidal curve fitting is applied to the data points along each circumferential direction of the PCS. The angle corresponding to the maximum of the estimated sinusoid function is determined to be the current direction, and the amplitude of this sinusoidal function is the current speed. For validation, the algorithm is tested against both simulated radar images and field data collected by a vertically-polarized X-band system and ground-truthed with measurements from an acoustic Doppler current profiler (ADCP. From the field data, it is observed that when the current speed is less than 0.5 m/s, the root mean square differences between the radar-derived and the ADCP-measured current speed and direction are 7.3 cm/s and 32.7°, respectively. The results indicate that the proposed procedure, unlike most existing current inversion schemes, is not susceptible to high current speeds and circumvents the need to consider aliasing. Meanwhile, the relatively low computational cost makes it an excellent choice in practical marine applications.

  17. Wide-band all-angle acoustic self-collimation by rectangular sonic crystals with elliptical bases

    International Nuclear Information System (INIS)

    Cicek, Ahmet; Kaya, Olgun Adem; Ulug, Bulent

    2011-01-01

    Self-collimation of acoustic waves in the whole angular range of ±90 0 in the second and third bands of a two-dimensional rectangular sonic crystal with elliptical basis is demonstrated by examining the band structure and equifrequency contours. 70% and 77% of the second and third bands are available for wide-band all-angle self-collimation spanning a bandwidth of approximately 29% and 25% of the central frequencies of the all-angle self-collimation frequency ranges, respectively. Self-collimation of waves over large distances with a small divergence of beam width in the transverse direction is demonstrated through computations based on the finite element method. The second and third bands available for self-collimation are seen to vary linearly in the vast mid-range where a small group velocity dispersion prevents temporal divergence of waves with different frequencies.

  18. Conductance of Conjugated Molecular Wires: Length Dependence, Anchoring Groups, and Band Alignment

    DEFF Research Database (Denmark)

    Peng, Guowen; Strange, Mikkel; Thygesen, Kristian Sommer

    2009-01-01

    , is not solely determined by the intrinsic band gap of the molecular wire but also depends on the anchoring group. This is because the alignment of the metal Fermi level with respect to the molecular levels is controlled by charge transfer and interface dipoles which in turn are determined by the local chemistry...

  19. Titanium K-Shell X-Ray Production from High Velocity Wire Arrays Implosions on the 20-MA Z Accelerator

    International Nuclear Information System (INIS)

    Apruzese, J.P.; Beg, F.N.; Clark, R.C.; Coverdale, C.A.; Davis, J.; Deeney, C.; Douglas, M.R.; Nash, T.J.; Ruiz-Comacho, J.; Spielman, R.B.; Struve, K.W.; Thornhill, J.W.; Whitney, K.G.

    1999-01-01

    The advent of the 20-MA Z accelerator [R.B. Spielman, C. Deeney, G.A. Chandler, et al., Phys. Plasmas 5, 2105, (1997)] has enabled implosions of large diameter, high-wire-number arrays of titanium to begin testing Z-pinch K-shell scaling theories. The 2-cm long titanium arrays, which were mounted on a 40-mm diameter, produced between 75±15 to 125±20 kJ of K-shell x-rays. Mass scans indicate that, as predicted, higher velocity implosions in the series produced higher x-ray yields. Spectroscopic analyses indicate that these high velocity implosions achieved peak electron temperatures from 2.7±0.1 to 3.2±0.2 keV and obtained a K-shell emission mass participation of up to 12%

  20. Room Temperature Thin Film Ba(x)Sr(1-x)TiO3 Ku-Band Coupled MicrostripPhase Shifters: Effects of Film Thickness, Doping, Annealing and Substrate Choice

    Science.gov (United States)

    VanKeuls, F. W.; Mueller, C. H.; Miranda, F. A.; Romanofsky, R. R.; Canedy, C. L.; Aggarwal, S.; Venkatesan, T.; Ramesh, R.; Horwitz, S.; Chang, W.

    1999-01-01

    We report on measurements taken on over twenty Ku-band coupled microstrip phase shifters (CMPS) using thin ferroelectric films of Ba(x)Sr(1-x)TiO3. This CMPS design is a recent innovation designed to take advantage of the high tunability and tolerate the high dielectric constant of ferroelectric films at Ku- and K-band frequencies. These devices are envisioned as a component in low-cost steerable beam phased area antennas, Comparisons are made between devices with differing film thickness, annealed vs unannealed, Mn-doped vs. undoped, and also substrates of LaAlO3 and MgO. A comparison between the CMPS structure and a CPW phase shifter was also made oil the same ferroelectric film.

  1. Offshore platform sourced pollution monitoring using space-borne fully polarimetric C and X band synthetic aperture radar.

    Science.gov (United States)

    Singha, Suman; Ressel, Rudolf

    2016-11-15

    Use of polarimetric SAR data for offshore pollution monitoring is relatively new and shows great potential for operational offshore platform monitoring. This paper describes the development of an automated oil spill detection chain for operational purposes based on C-band (RADARSAT-2) and X-band (TerraSAR-X) fully polarimetric images, wherein we use polarimetric features to characterize oil spills and look-alikes. Numbers of near coincident TerraSAR-X and RADARSAT-2 images have been acquired over offshore platforms. Ten polarimetric feature parameters were extracted from different types of oil and 'look-alike' spots and divided into training and validation dataset. Extracted features were then used to develop a pixel based Artificial Neural Network classifier. Mutual information contents among extracted features were assessed and feature parameters were ranked according to their ability to discriminate between oil spill and look-alike spots. Polarimetric features such as Scattering Diversity, Surface Scattering Fraction and Span proved to be most suitable for operational services. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. An X- and Q-band Fe3+ EPR study of nanoparticles of magnetic semiconductor Zn1−xFexO

    International Nuclear Information System (INIS)

    Misra, Sushil K.; Andronenko, S.I.; Thurber, A.; Punnoose, A.; Nalepa, A.

    2014-01-01

    EPR studies on two types of nanoparticles of Fe 3+ doped, 0.1–10%, ZnO, NL and QJ, prepared using similar chemical hydrolysis methods, in diethylene glycol, and in denatured ethanol solutions, respectively, were carried out at X-band (∼9.5 GHz) at 77 K and at Q-band (∼34.0 GHz) at 10, 80, and 295 K. To interpret the experimental results, EPR spectra were simulated by exact diagonalization of the spin-Hamiltonian matrix to identify the Fe ions at different magnetically active sites in these samples. The simulation for NL samples revealed that they contained (i) Fe 3+ ions, which substituted for Zn ions, the zero-field splitting (ZFS) parameter which has a large distribution over the sample due to oxygen vacancies in the second coordination sphere; (ii) EPR signal from surface oxygen defects; and (iii) ferromagnetically (FM) coupled Fe ions with concentration of Fe more than 1%. The EPR spectra for QJ samples are very different from those for NL samples, exhibiting only rather intense FM EPR lines. The FM and EPR spectra in NL and/or QJ samples are found to vary strongly with differences in the surface morphology of nanoparticles. - Highlights: • X and Q band EPR studies on NL and QJ nanoparticles of Fe 3+ doped ZnO at 10, 80, and 295 K. • Fe ions are present at different magnetically active sites in these samples. • NL samples consist of paramagnetic Fe 3+ ions, and ferromagnetically coupled Fe ions. • QJ samples exhibit only intense ferromagnetic lines, different from QJ. • Spectra vary strongly with the surface morphology of nanoparticles

  3. Hot phonon generation by split-off hole band electrons in AlxGa1-xAs alloys investigated by picosecond Raman scattering

    International Nuclear Information System (INIS)

    Jacob, J.M.; Kim, D.S.; Zhou, J.F.; Song, J.J.

    1992-01-01

    The initial generation of hot LO phonons by the relaxation of hot carriers in GaAs and Al x Ga 1-x As alloy semiconductors is studied. Within the initial 2ps of photoexcitation, only those electrons originating from the split-off hole bands are found to generate a significant number of I-valley hot phonons when photon energies of 2.33eV are used. A picosecond Raman scattering technique is used to determine the hot phonon occupation number in a series of MBE grown Al x Ga 1-x As samples with 0≤x≤0.39. The Stokes and anti-Stokes lines were measured for both GaAs-like and AlAs-like LO phonon modes to determine their occupation numbers. The authors observe a rapid decrease in the phonon occupation numbers as the aluminum concentration increases beyond x = 0.2. This rapid decrease is explained by considering only those electrons photoexcited from the split-off hole band. Almost all of the electrons originating from the heavy and light-hole bands are shown to quickly transfer and remain in the X and L valleys without generating significant numbers of hot LO phonons during the initial 2ps and at a carrier density of 10 17 cm -3 . A model based upon the instantaneous thermalization of hot electrons photoexcited from the split-off hole bands is used to fit the data. They have obtained very good agreement between experiment and theory. This work provides a clear understanding to the relaxation of Γ valley hot electrons by the generation of hot phonons on subpicosecond and picosecond time scales, which has long standing implications to previous time resolved Raman experiments

  4. SLAC High Gradient Testing of a KEK X-Band Accelerator Structure

    International Nuclear Information System (INIS)

    Loewen, Rod

    2000-01-01

    The high accelerating gradients required for future linear colliders demands a better study of field emission and RF breakdown in accelerator structures. Changes in structure geometry, vacuum pumping, fabrication methods, and surface finish can all potentially impact the conditioning process, dark current emission, and peak RF power handling capability. Recent tests at SLAC of KEK's ''M2'' travelling wave x-band accelerator section provides an opportunity to investigate some of these effects by comparing its performance to previously high power tested structures at SLAC. In addition to studying ultimate power limitations, this test also demonstrates the use of computer automated conditioning to reach practical, achievable gradients

  5. Challenges with space-time rainfall in urban hydrology highlighted with a semi-distributed model using C-band and X-band radar data

    Science.gov (United States)

    da Silva Rocha Paz, Igor; Ichiba, Abdellah; Skouri-Plakali, Ilektra; Lee, Jisun; Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel

    2017-04-01

    Climate change and global warming are expected to make precipitation events more frequent, more severe and more local. This may have serious consequences for human health, the environment, cultural heritage, economic activities, utilities and public service providers. Then precipitation risk and water management is a key challenge for densely populated urban areas. Applications derived from high (time and space) resolution observation of precipitations are to make our cities more weather-ready. Finer resolution data available from X-band dual radar measurements enhance engineering tools as used for urban planning policies as well as protection (mitigation/adaptation) strategies to tackle climate-change related weather events. For decades engineering tools have been developed to work conveniently either with very local rain gauge networks, or with mainly C-band weather radars that have gradually been set up for space-time remote sensing of precipitation. Most of the time, the C-band weather radars continue to be calibrated by the existing rain gauge networks. Inhomogeneous distributions of rain gauging networks lead to only a partial information on the rainfall fields. In fact, the statistics of measured rainfall is strongly biased by the fractality of the measuring networks. This fractality needs to be properly taken in to account to retrieve the original properties of the rainfall fields, in spite of the radar data calibration. In this presentation, with the help of multifractal analysis, we first demonstrate that the semi-distributed hydrological models statistically reduce the rainfall fields into rainfall measured by a much scarcer network of virtual rain gauges. For this purpose, we use C-band and X-band radar data. The first has a resolution of 1 km in space and 5 min in time and is in fact a product provided by RHEA SAS after treating the Météo-France C-band radar data. The latter is measured by the radar operated at Ecole des Ponts and has a resolution of

  6. Lamb wave band gaps in a double-sided phononic plate

    Science.gov (United States)

    Wang, Peng; Chen, Tian-Ning; Yu, Kun-Peng; Wang, Xiao-Peng

    2013-02-01

    In this paper, we report on the theoretical investigation of the propagation characteristics of Lamb wave in a phononic crystal structure constituted by a square array of cylindrical stubs deposited on both sides of a thin homogeneous plate. The dispersion relations, the power transmission spectra, and the displacement fields of the eigenmodes are studied by using the finite-element method. We investigate the evolution of band gaps in the double-sided phononic plate with stub height on both sides arranged from an asymmetrical distribution to a symmetrical distribution gradually. Numerical results show that as the double stubs in a unit cell arranged more symmetrically on both sides, band width shifts, new band gaps appear, and the bands become flat due to localized resonant modes which couple with plate modes. Specially, more band gaps and flat bands can be found in the symmetrical system as a result of local resonances of the stubs which interact in a stronger way with the plate modes. Moreover, the symmetrical double-sided plate exhibits lower and smaller band gap than that of the asymmetrical plate. These propagation properties of elastic or acoustic waves in the double-sided plate can potentially be utilized to generate filters, slow the group velocity, low-frequency sound insulation, and design acoustic sensors.

  7. The Soft X-Ray Spectra of Sulfur Compounds.

    Science.gov (United States)

    Zhou, Ling

    1995-01-01

    The sulfur compounds including CdS, ZnS, rm MoS_2, WS_2, NiS, FeS, GaS, SnS, MgS and Alloy rm ZnS_{x }Se_{1-x} were investigated by using photon/e-beam excited soft x-ray spectroscopy through SXA, SXE, SXF and inelastic Resonant Raman scattering and resonant elastic scattering processes. For valence bands, the PDOS of S L_{2,3}, Zn M_{2,3}, Se M _{4,5}, bands locations, band gaps Eg, core level spin splitting, the lifetime broadening of valence band t_{1/2}, branching ratio of rm L_2/L_3 and shallow d level and exciton state were measured in some of these materials respectively. The excitation mechanism or threshold effects were studied for CdS, ZnS, MoS_2, WS_2, FeS, NiS, and alloy. In photon excited S L_ {2,3}^ectra, local core levels with spin splitting were found to charge threshold effects. The threshold effects are also found to be influenced by resonant elastic and inelastic scattering process. A simple model and the second order perturbation theory are used to explain the observed inelastic Raman scattering of Zn M _{2,3} spectra near d threshold. The d participation in the chemical bonding and interactions was studied. Atomiclike d bands were found in FeS and NiS from strong d-d and d-p couplings. Two groups of d bands were observed in Transitional Metal Sulfides (TMS) and the no-bonding group with a few d bands was found to across whole valence bands in TMS. The direct connection between valence bands and conduction bands is built and some conduction bands were studied. A study of alloy was included briefly. These experiments provide a rich information about TMS, and prove that Soft X-ray Spectroscopy is a powerful, precise and reliable tool in the study of fine electronic band structure in solids.

  8. Effect of group velocity mismatch on acousto-optic interaction of ultrashort laser pulses

    International Nuclear Information System (INIS)

    Yushkov, K B; Molchanov, V Ya

    2011-01-01

    Equations describing acousto-optic diffraction of ultrashort laser pulses in an anisotropic medium are derived, taking into account the group velocity mismatch of optical eigenmodes. It is shown that the solution of the modified coupled-mode equations taking into account the group delay is characterised by an increase in the pulse duration, a decrease in diffraction efficiency, a change in the shape of the wave packet envelope, as well as by an increase in the width of the transmission function.

  9. 3D shear wave velocity structure revealed with ambient noise tomography on a DAS array

    Science.gov (United States)

    Zeng, X.; Thurber, C. H.; Wang, H. F.; Fratta, D.

    2017-12-01

    An 8700-m Distributed Acoustic Sensing (DAS) cable was deployed at Brady's Hot Springs, Nevada in March 2016 in a 1.5 by 0.5 km study area. The layout of the DAS array was designed with a zig-zag geometry to obtain relatively uniform areal and varied angular coverage, providing very dense coverage with a one-meter channel spacing. This array continuously recorded signals of a vibroseis truck, earthquakes, and traffic noise during the 15-day deployment. As shown in a previous study (Zeng et al., 2017), ambient noise tomography can be applied to DAS continuous records to image shear wave velocity structure in the near surface. To avoid effects of the vibroseis truck operation, only continuous data recorded during the nighttime was used to compute noise cross-correlation functions for channel pairs within a given linear segment. The frequency band of whitening was set at 5 to 15 Hz and the length of the cross-correlation time window was set to 60 second. The phase velocities were determined using the multichannel analysis of surface waves (MASW) methodology. The phase velocity dispersion curve was then used to invert for shear wave velocity profiles. A preliminarily velocity model at Brady's Hot Springs (Lawrence Livermore National Laboratory, 2015) was used as the starting model and the sensitivity kernels of Rayleigh wave group and phase velocities were computed with this model. As the sensitivity kernel shows, shear wave velocity in the top 200 m can be constrained with Rayleigh wave group and phase velocities in our frequency band. With the picked phase velocity data, the shear wave velocity structure can be obtained via Occam's inversion (Constable et al., 1987; Lai 1998). Shear wave velocity gradually increases with depth and it is generally faster than the Lawrence Livermore National Laboratory (2015) model. Furthermore, that model has limiting constraints at shallow depth. The strong spatial variation is interpreted to reflect the different sediments and

  10. Laser polarization dependent and magnetically control of group velocity in a dielectric medium doped with nanodiamond nitrogen vacancy centers

    Energy Technology Data Exchange (ETDEWEB)

    Asadpour, Seyyed Hossein; Rahimpour Soleimani, H., E-mail: Rahimpour@guilan.ac.ir

    2014-03-01

    In this paper, group velocity control of Gaussian beam in a dielectric medium doped with nanodiamond nitrogen vacancy (NV) centers under optical excitation is discussed. The shape of transmitted and reflected pulses from dielectric can be tuned by changing the intensity of magnetic field and polarization of the control beam. The effect of intensity of control beam on group velocity is also investigated.

  11. Optimizing measurements of cluster velocities and temperatures for CCAT-prime and future surveys

    Science.gov (United States)

    Mittal, Avirukt; de Bernardis, Francesco; Niemack, Michael D.

    2018-02-01

    Galaxy cluster velocity correlations and mass distributions are sensitive probes of cosmology and the growth of structure. Upcoming microwave surveys will enable extraction of velocities and temperatures from many individual clusters for the first time. We forecast constraints on peculiar velocities, electron temperatures, and optical depths of galaxy clusters obtainable with upcoming multi-frequency measurements of the kinematic, thermal, and relativistic Sunyaev-Zeldovich effects. The forecasted constraints are compared for different measurement configurations with frequency bands between 90 GHz and 1 THz, and for different survey strategies for the 6-meter CCAT-prime telescope. We study methods for improving cluster constraints by removing emission from dusty star forming galaxies, and by using X-ray temperature priors from eROSITA. Cluster constraints are forecast for several model cluster masses. A sensitivity optimization for seven frequency bands is presented for a CCAT-prime first light instrument and a next generation instrument that takes advantage of the large optical throughput of CCAT-prime. We find that CCAT-prime observations are expected to enable measurement and separation of the SZ effects to characterize the velocity, temperature, and optical depth of individual massive clusters (~1015 Msolar). Submillimeter measurements are shown to play an important role in separating these components from dusty galaxy contamination. Using a modular instrument configuration with similar optical throughput for each detector array, we develop a rule of thumb for the number of detector arrays desired at each frequency to optimize extraction of these signals. Our results are relevant for a future "Stage IV" cosmic microwave background survey, which could enable galaxy cluster measurements over a larger range of masses and redshifts than will be accessible by other experiments.

  12. Valence band photoemission from in-situ grown GaAs(100)-c(4 x 4)

    Czech Academy of Sciences Publication Activity Database

    Jiříček, Petr; Cukr, Miroslav; Bartoš, Igor; Adell, M.; Strasser, T.; Schattke, W.

    2006-01-01

    Roč. 56, č. 1 (2006), s. 21-26 ISSN 0011-4626. [Symposium on Surface Physics /10./. Praha, 11.07.2005-15.07.2005] R&D Projects: GA ČR(CZ) GA202/04/0994 Institutional research plan: CEZ:AV0Z10100521 Keywords : GaAs(100)-c(4X4) * surface states * band structure * structure plot Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.568, year: 2006

  13. Band offsets in HfTiO/InGaZnO4 heterojunction determined by X-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    He, G.; Chen, X.F.; Lv, J.G.; Fang, Z.B.; Liu, Y.M.; Zhu, K.R.; Sun, Z.Q.; Liu, M.

    2015-01-01

    Highlights: • Band offsets in HfTiO/InGaZnO 4 heterojunction were determined by XPS. • Valence band offset of HfTiO/IGZO heterojunction is determined to be 0.35 eV. • Conduction band offset of 1.61 eV is deduced for HfTiO/IGZO heterojunction. - Abstract: In current report, X-ray photoelectron spectroscopy has been pursued to obtain the valence band discontinuity (ΔE v ) of sputter deposited HfTiO/InZnGaO 4 (IGZO) heterostructures. A ΔE v value of 0.32 ± 0.1 eV was obtained by using the Ga 2p3/2, Zn 2p3/2, and In 3d5/2 energy levels as references. Taking into consideration the experimental band gaps of 5.35 eV and 3.39 eV for HfTiO and IGZO thin films measured by absorption method, respectively, this would result in a conduction band offset of 1.64 eV in this heterostructure

  14. Land cover classification accuracy from electro-optical, X, C, and L-band Synthetic Aperture Radar data fusion

    Science.gov (United States)

    Hammann, Mark Gregory

    The fusion of electro-optical (EO) multi-spectral satellite imagery with Synthetic Aperture Radar (SAR) data was explored with the working hypothesis that the addition of multi-band SAR will increase the land-cover (LC) classification accuracy compared to EO alone. Three satellite sources for SAR imagery were used: X-band from TerraSAR-X, C-band from RADARSAT-2, and L-band from PALSAR. Images from the RapidEye satellites were the source of the EO imagery. Imagery from the GeoEye-1 and WorldView-2 satellites aided the selection of ground truth. Three study areas were chosen: Wad Medani, Sudan; Campinas, Brazil; and Fresno- Kings Counties, USA. EO imagery were radiometrically calibrated, atmospherically compensated, orthorectifed, co-registered, and clipped to a common area of interest (AOI). SAR imagery were radiometrically calibrated, and geometrically corrected for terrain and incidence angle by converting to ground range and Sigma Naught (?0). The original SAR HH data were included in the fused image stack after despeckling with a 3x3 Enhanced Lee filter. The variance and Gray-Level-Co-occurrence Matrix (GLCM) texture measures of contrast, entropy, and correlation were derived from the non-despeckled SAR HH bands. Data fusion was done with layer stacking and all data were resampled to a common spatial resolution. The Support Vector Machine (SVM) decision rule was used for the supervised classifications. Similar LC classes were identified and tested for each study area. For Wad Medani, nine classes were tested: low and medium intensity urban, sparse forest, water, barren ground, and four agriculture classes (fallow, bare agricultural ground, green crops, and orchards). For Campinas, Brazil, five generic classes were tested: urban, agriculture, forest, water, and barren ground. For the Fresno-Kings Counties location 11 classes were studied: three generic classes (urban, water, barren land), and eight specific crops. In all cases the addition of SAR to EO resulted

  15. X- and Q-band EPR studies on fine powders of irradiated plants. New approach for detection of their radiation history by using Q-band EPR spectrometry

    International Nuclear Information System (INIS)

    Yordanov, Nicola D.; Aleksieva, Katerina

    2004-01-01

    X- and Q-band EPR studies after γ-irradiation of some dry spices and aromatic herbs are reported. Before irradiation all samples show only one singlet line in X-band EPR, whereas the Q-band EPR spectrum of the same samples is a superposition of two individual spectra--one corresponding to the above EPR signal, with an anisotropic spectrum, and a second one consisting of six lines due to the Mn 2+ naturally present in plants. The radiation induced EPR signal due to cellulose free radicals was not detected after γ-irradiation, but only the increase of the natural signal present before the irradiation. The fading kinetic of this EPR signal was monitored in three cases--when samples were kept in plastic bags without any special conditioning after irradiation, when samples were covered with paraffin before irradiation and when samples were dried at 60 deg. C for 1 h before irradiation. The studies show that stability of radiation induced EPR signals decreases in the order of: paraffin covered > heated before irradiation > kept at room conditions. The two EPR spectra in the Q-band--one with radiation dependent intensity and a second due to Mn 2+ , which is radiation independent allow identification of previous radiation treatment based on the fact that Mn 2+ quantity in the sample is constant whereas the quantity of radiation-induced free radicals is temperature dependent. It was found that for irradiated samples the ratio between EPR intensity of the free radicals and that of Mn 2+ before and after heating decreases with 50-60% whereas for non-irradiated samples it is ca. 10-15%

  16. Determination of the filtration velocities and mean velocity in ground waters using radiotracers

    International Nuclear Information System (INIS)

    Duran P, Oscar; Diaz V, Francisco; Heresi M, Nelida

    1994-01-01

    An experimental method to determine filtration, or, Darcy velocity and mean velocity in underground waters using radiotracers, is described. After selecting the most appropriate tracers, from 6 chemical compounds, to measure water velocity, a method to measure filtration velocity was developed. By fully labelling the water column with 2 radioisotopes, Br and tritium, almost identical values were obtained for the aquifer filtration velocity in the sounding S1. This value was 0.04 m/d. Field porosity was calculated at 11% and mean velocity at 0.37 m.d. With the filtration velocity value and knowing the hydraulic variation between the soundings S1 and S2 placed at 10 meters, field permeability was estimated at 2.4 x 10 m/s. (author)

  17. Microwave absorption properties of flake-shaped Co particles composites at elevated temperature (293-673 K) in X band

    Science.gov (United States)

    Wang, Guowu; Li, Xiling; Wang, Peng; Zhang, Junming; Wang, Dian; Qiao, Liang; Wang, Tao; Li, Fashen

    2018-06-01

    The complex permeability and permittivity of the easy-plane anisotropic Co/polyimide composite at high temperature (293-673 K) in X band were measured. The results show that both the complex permeability and permittivity increase with the increase of temperature in the measured temperature range. The calculated absorption properties display that the intensity of the reflection loss (RL) peak first increases and then decreases with the increase of temperature, and reaches the maximum (-52 dB) at 523 K. At each temperature, the composite can achieve the RL exceeding -10 dB in the whole X band. The composite can even work stably for more than 20 min with the excellent absorption performance under 673 K. In addition, the RL performance of the composite at high temperature is better than that at room temperature.

  18. X-BAND CIRCULARLY POLARIZED RECTENNAS FOR MICROWAVE POWER TRANSMISSION APPLICATIONS

    Institute of Scientific and Technical Information of China (English)

    Yang Xuexia; Xu Junshu; Xu Deming; Xu Changlong

    2008-01-01

    Circularly polarized rectennas operating at X-band are studied in this paper. The quasi-square patches fed by aperture coupling are used as the circularly polarized receiving antennas,which are easily matched and integrated with the circuits of rectennas. The double-layer structure not only minimizes the size of the rectennas but also decreases the effects of the circuits on the antenna. The receiving elements have broader bandwidth and higher gain than the single-layer patches.Two rectennas operating at 10GHz are designed, fabricated and measured. The voltage of 3.86V on a load of 200Ωis measured and a high RF-DC conversion efficiency of 75% is obtained at 9.98GHz. It is convenient for this kind of rectennas to form large arrays for high power applications.

  19. A capacitive membrane MEMS microwave power sensor in the X-band based on GaAs MMIC technology

    International Nuclear Information System (INIS)

    Su Shi; Liao Xiaoping

    2009-01-01

    This paper presents the modeling, fabrication, and measurement of a capacitive membrane MEMS microwave power sensor. The sensor measures microwave power coupled from coplanar waveguide (CPW) transmission lines by a MEMS membrane and then converts it into a DC voltage output by using thermopiles. Since the fabrication process is fully compatible with the GaAs monolithic microwave integrated circuit (MMIC) process, this sensor could be conveniently embedded into MMIC. From the measured DC voltage output and S-parameters, the average sensitivity in the X-band is 225.43 μV/mW, while the reflection loss is below -14 dB. The MEMS microwave power sensor has good linearity with a voltage standing wave ration of less than 1.513 in the whole X-band. In addition, the measurements using amplitude modulation signals prove that the modulation index directly influences the output DC voltage.

  20. Design and Measurements of an X-Band Accelerating Cavity for SPARC

    CERN Document Server

    Alesini, David; Falone, Antonio; Ferrario, Massimo; Migliorati, Mauro; Mostacci, Andrea; Palpini, Federica; Palumbo, Luigi; Spataro, Bruno

    2005-01-01

    The paper presents the design of an X-band accelerating section for linearizing the longitudinal phase space in the Frascati Linac Coherent Light Source (SPARC). The structure, operating on the pi standing wave mode, is a 9 cells structure feeded by a central waveguide coupler and has been designed to obtain a 5 MV accelerating voltage. The 2D profile has been obtained using the e.m. codes SUPERFISH and OSCARD2D while the coupler has been designed using HFSS. Bead-pull measurement made on a copper prototype are illustrated and compared with the numerical results. Mechanical details of the realized prototype and RF properties of the structure as a function of the assembly characteristics are also discussed.

  1. Non-toxic novel route synthesis and characterization of nanocrystalline ZnS{sub x}Se{sub 1−x} thin films with tunable band gap characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Agawane, G.L., E-mail: agawaneganesh@gmail.com [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Shin, Seung Wook [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of); Vanalakar, S.A. [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Moholkar, A.V. [Electrochemical Mat. Lab., Department of Physics, Shivaji University, Kolhapur 416-004 (India); Gurav, K.V.; Suryawanshi, M.P. [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Lee, Jeong Yong [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of); Yun, Jae Ho, E-mail: yunjh92@kier.re.kr [Photovoltaic Research Group, KIER, Jang-Dong, Yuseong-Gu, Daejeon 305-343 (Korea, Republic of); Kim, Jin Hyeok, E-mail: jinhyeok@chonnam.ac.kr [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of)

    2014-07-01

    Highlights: • A simple, inexpensive, and non-toxic CBD route is used to deposit ZnS thin films. • The ZnS{sub x}Se{sub 1−x} thin films formation takes place via annealing of ZnS thin films in Se atmosphere. • S/(S + Se) ratio found to be temperature dependent and easy tuning of band gap has been done by Se atom deposition. - Abstract: An environmentally benign chemical bath deposition (CBD) route was employed to deposit zinc sulfide (ZnS) thin films. The CBD-ZnS thin films were further selenized in a furnace at various temperatures viz. 200, 300, 400, and 500 °C and the S/(S + Se) ratio was found to be dependent on the annealing temperature. The effects of S/(S + Se) ratio on the structural, compositional and optical properties of the ZnS{sub x}Se{sub 1−x} (ZnSSe) thin films were investigated. EDS analysis showed that the S/(S + Se) ratio decreased from 0.8 to 0.6 when the film annealing temperature increased from 200 to 500 °C. The field emission scanning electron microscopy and atomic force microscopy studies showed that all the films were uniform, pin hole free, smooth, and adhered well to the glass substrate. The X-ray diffraction study on the ZnSSe thin films showed the formation of the cubic phase, except for the unannealed ZnSSe thin film, which showed an amorphous phase. The X-ray photoelectron spectroscopy revealed Zn-S, Zn-Se, and insignificant Zn-OH bonds formation from the Zn 2p{sub 3/2}, S 2p, Se 3d{sub 5/2}, and O 1s atomic states, respectively. The ultraviolet–visible spectroscopy study showed ∼80% transmittance in the visible region for all the ZnSSe thin films having various absorption edges. The tuning of the band gap energy of the ZnSSe thin films was carried out by selenizing CBD-ZnS thin films, and as the S/(S + Se) ratio decreased from 0.8 to 0.6, the band gap energy decreased from 3.20 to 3.12 eV.

  2. Microstructure evolution associated with adiabatic shear bands and shear band failure in ballistic plug formation in Ti-6Al-4V targets

    International Nuclear Information System (INIS)

    Murr, L.E.; Ramirez, A.C.; Gaytan, S.M.; Lopez, M.I.; Martinez, E.Y.; Hernandez, D.H.; Martinez, E.

    2009-01-01

    The microstructures and microstructure evolution associated with adiabatic shear band (ASB) formation in ballistic plugging in thick (2.5 cm) Ti-6Al-4V targets impacted by cylindrical, 4340 steel projectiles (2.0 cm in height) at impact velocities ranging from 633 m/s to 1027 m/s (just above the ballistic limit) were investigated by optical and transmission electron microscopy. ASB width increased from 10 μm to 21 μm as the velocity increased. ASB evolution was accompanied by the evolution of dark deformation bands composed of α' martensite platelets which increased in density with increasing impact velocity. The corresponding Vickers microindentation hardness also increased from HV 619 to HV 632 in contrast to the surrounding matrix microindentation hardness of HV 555. These deformation bands were not necessarily precursors to ASB formation. The ASB average Vickers microindentation hardness was essentially constant at HV 645, a 16% increase over the matrix. This constant microindentation hardness was characterized by a consistent DRX grain structure which varied from equiaxed, defect-free grains (∼2 μm diameter) to heavily dislocated, equiaxed grains. Cracks nucleating and propagating within the ABSs were observed to increase from 8% to 87% of the ASB length with increasing impact velocity.

  3. Investigation of LO-leakage cancellation and DC-offset influence on flicker-noise in X-band mixers

    DEFF Research Database (Denmark)

    Michaelsen, Rasmus; Johansen, Tom; Tamborg, Kjeld

    2012-01-01

    This paper describes an investigation on the influences in 1/f noise of LO-leakage and DC-offset cancellation for X-band mixers. Conditions for LO-leakage cancellation and zero DC-offset is derived. Measurements on a double balanced diode mixer shows an improvement in noise figure from 14.3dB to ...

  4. A First Layered Crustal Velocity Model for the Western Solomon Islands: Inversion of Measured Group Velocity of Surface Waves using Ambient Noise Cross-Correlation

    Science.gov (United States)

    Ku, C. S.; Kuo, Y. T.; Chao, W. A.; You, S. H.; Huang, B. S.; Chen, Y. G.; Taylor, F. W.; Yih-Min, W.

    2017-12-01

    Two earthquakes, MW 8.1 in 2007 and MW 7.1 in 2010, hit the Western Province of Solomon Islands and caused extensive damage, but motivated us to set up the first seismic network in this area. During the first phase, eight broadband seismic stations (BBS) were installed around the rupture zone of 2007 earthquake. With one-year seismic records, we cross-correlated the vertical component of ambient noise recorded in our BBS and calculated Rayleigh-wave group velocity dispersion curves on inter-station paths. The genetic algorithm to invert one-dimensional crustal velocity model is applied by fitting the averaged dispersion curves. The one-dimensional crustal velocity model is constituted by two layers and one half-space, representing the upper crust, lower crust, and uppermost mantle respectively. The resulted thickness values of the upper and lower crust are 6.4 and 14.2 km, respectively. Shear-wave velocities (VS) of the upper crust, lower crust, and uppermost mantle are 2.53, 3.57 and 4.23 km/s with the VP/VS ratios of 1.737, 1.742 and 1.759, respectively. This first layered crustal velocity model can be used as a preliminary reference to further study seismic sources such as earthquake activity and tectonic tremor.

  5. An X-band waveguide measurement technique for the accurate characterization of materials with low dielectric loss permittivity

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Kenneth W., E-mail: kenneth.allen@gtri.gatech.edu; Scott, Mark M.; Reid, David R.; Bean, Jeffrey A.; Ellis, Jeremy D.; Morris, Andrew P.; Marsh, Jeramy M. [Advanced Concepts Laboratory, Georgia Tech Research Institute, Atlanta, Georgia 30318 (United States)

    2016-05-15

    In this work, we present a new X-band waveguide (WR90) measurement method that permits the broadband characterization of the complex permittivity for low dielectric loss tangent material specimens with improved accuracy. An electrically long polypropylene specimen that partially fills the cross-section is inserted into the waveguide and the transmitted scattering parameter (S{sub 21}) is measured. The extraction method relies on computational electromagnetic simulations, coupled with a genetic algorithm, to match the experimental S{sub 21} measurement. The sensitivity of the technique to sample length was explored by simulating specimen lengths from 2.54 to 15.24 cm, in 2.54 cm increments. Analysis of our simulated data predicts the technique will have the sensitivity to measure loss tangent values on the order of 10{sup −3} for materials such as polymers with relatively low real permittivity values. The ability to accurately characterize low-loss dielectric material specimens of polypropylene is demonstrated experimentally. The method was validated by excellent agreement with a free-space focused-beam system measurement of a polypropylene sheet. This technique provides the material measurement community with the ability to accurately extract material properties of low-loss material specimen over the entire X-band range. This technique could easily be extended to other frequency bands.

  6. Facebook Band Director's Group: Member Usage Behaviors and Perceived Satisfaction for Meeting Professional Development Needs

    Science.gov (United States)

    Rickels, David A.; Brewer, Wesley D.

    2017-01-01

    The purpose of this study was to investigate participation in a Facebook social media community known as Band Director's Group (BDG) through examination of members' demographic profiles, self-reported usage behaviors, and perceptions about how group activity satisfies their professional development needs. Respondents to an online survey (n = 336)…

  7. Band alignment of ZnO/multilayer MoS{sub 2} interface determined by x-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xinke, E-mail: xkliu@szu.edu.cn, E-mail: liuwj@szu.edu.cn; He, Jiazhu; Chen, Le; Li, Kuilong; Jia, Fang; Zeng, Yuxiang; Lu, Youming; Zhu, Deliang; Liu, Wenjun, E-mail: xkliu@szu.edu.cn, E-mail: liuwj@szu.edu.cn [College of Materials Science and Engineering, Nanshan District Key Lab for Biopolymer and Safety Evaluation, Shenzhen University, 3688 Nanhai Ave, Shenzhen 518060 (China); Zhang, Yuan [School of Physics and Electronic Information, Hua Bei Normal University, 100 Dongshan Road, Huai Bei 235000 (China); Liu, Qiang; Yu, Wenjie [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS, 865 Chang Ning Road, Shanghai 200050 (China); Wu, Jing [Institute of Materials research and Engineering (IMRE), 2 Fusionopolis Way, Innovis, #08-03, 138634 Singapore (Singapore); He, Zhubing [Department of Materials Science and Engineering, South University of Science and Technology of China, 1088 Xueyuan Road, Shenzhen 518055 (China); Ang, Kah-Wee [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117583 Singapore (Singapore)

    2016-08-15

    The energy band alignment between ZnO and multilayer (ML)-MoS{sub 2} was characterized using high-resolution x-ray photoelectron spectroscopy. The ZnO film was deposited using an atomic layer deposition tool, and ML-MoS{sub 2} was grown by chemical vapor deposition. A valence band offset (VBO) of 3.32 eV and a conduction band offset (CBO) of 1.12 eV were obtained for the ZnO/ML-MoS{sub 2} interface without any treatment. With CHF{sub 3} plasma treatment, a VBO and a CBO across the ZnO/ML-MoS{sub 2} interface were found to be 3.54 eV and 1.34 eV, respectively. With the CHF{sub 3} plasma treatment, the band alignment of the ZnO/ML-MoS{sub 2} interface has been changed from type II or staggered band alignment to type III or misaligned one, which favors the electron-hole pair separation. The band alignment difference is believed to be dominated by the down-shift in the core level of Zn 2p or the interface dipoles, which is caused by the interfacial layer rich in F.

  8. Band Offset Measurements in Atomic-Layer-Deposited Al2O3/Zn0.8Al0.2O Heterojunction Studied by X-ray Photoelectron Spectroscopy.

    Science.gov (United States)

    Yan, Baojun; Liu, Shulin; Heng, Yuekun; Yang, Yuzhen; Yu, Yang; Wen, Kaile

    2017-12-01

    Pure aluminum oxide (Al 2 O 3 ) and zinc aluminum oxide (Zn x Al 1-x O) thin films were deposited by atomic layer deposition (ALD). The microstructure and optical band gaps (E g ) of the Zn x Al 1-x O (0.2 ≤ x ≤ 1) films were studied by X-ray diffractometer and Tauc method. The band offsets and alignment of atomic-layer-deposited Al 2 O 3 /Zn 0.8 Al 0.2 O heterojunction were investigated in detail using charge-corrected X-ray photoelectron spectroscopy. In this work, different methodologies were adopted to recover the actual position of the core levels in insulator materials which were easily affected by differential charging phenomena. Valence band offset (ΔE V ) and conduction band offset (ΔE C ) for the interface of the Al 2 O 3 /Zn 0.8 Al 0.2 O heterojunction have been constructed. An accurate value of ΔE V  = 0.82 ± 0.12 eV was obtained from various combinations of core levels of heterojunction with varied Al 2 O 3 thickness. Given the experimental E g of 6.8 eV for Al 2 O 3 and 5.29 eV for Zn 0.8 Al 0.2 O, a type-I heterojunction with a ΔE C of 0.69 ± 0.12 eV was found. The precise determination of the band alignment of Al 2 O 3 /Zn 0.8 Al 0.2 O heterojunction is of particular importance for gaining insight to the design of various electronic devices based on such heterointerface.

  9. Interference effects on quantum light group velocity in cavity induced transparency

    International Nuclear Information System (INIS)

    Eilam, Asaf; Thanopulos, Ioannis

    2015-01-01

    We investigate the propagation of a quantized probe field in a dense medium composed of three-level Λ-type systems under cavity electromagnetically induced transparency conditions. We treat the medium as composed of collective states of the three-level systems while the light-medium interaction occurs within clusters of such collective states depending on the photon number state of the probe field. We observe slower group velocity for lower photon number input probe field only under conditions of no interference between different clusters of collective states in the system. (paper)

  10. Joint European x-ray monitor (JEM-X): x-ray monitor for ESA's

    DEFF Research Database (Denmark)

    Schnopper, H.W.; Budtz-Joergensen, C.; Westergaard, Niels Jørgen Stenfeldt

    1996-01-01

    JEM-X will extend the energy range of the gamma ray instruments on ESA's INTEGRAL mission (SPI, IBIS) to include the x-ray band. JEM-X will provide images with arcminute angular resolution in the 2 - 60 keV band. The baseline photon detection system consists of two identical, high pressure, imagi...

  11. Hybrid density functional theory study of Cu(In1−xGaxSe2 band structure for solar cell application

    Directory of Open Access Journals (Sweden)

    Xu-Dong Chen

    2014-08-01

    Full Text Available Cu(In1−xGaxSe2 (CIGS alloy based thin film photovoltaic solar cells have attracted more and more attention due to its large optical absorption coefficient, long term stability, low cost and high efficiency. However, the previous theoretical investigation of this material with first principle calculation cannot fulfill the requirement of experimental development, especially the accurate description of band structure and density of states. In this work, we use first principle calculation based on hybrid density functional theory to investigate the feature of CIGS, with B3LYP applied in the CuIn1−xGaxSe2 stimulation of the band structure and density of states. We report the simulation of the lattice parameter, band gap and chemical composition. The band gaps of CuGaSe2, CuIn0.25Ga0.75Se2, CuIn0.5Ga0.5Se2, CuIn0.75Ga0.25Se2 and CuInSe2 are obtained as 1.568 eV, 1.445 eV, 1.416 eV, 1.275 eV and 1.205 eV according to our calculation, which agree well with the available experimental values. The band structure of CIGS is also in accordance with the current theory.

  12. X-band rf driven free electron laser driver with optics linearization

    Directory of Open Access Journals (Sweden)

    Yipeng Sun (孙一鹏

    2014-11-01

    Full Text Available In this paper, a compact hard X-ray free electron lasers (FEL design is proposed with all X-band rf acceleration and two stage bunch compression. It eliminates the need of a harmonic rf linearization section by employing optics linearization in its first stage bunch compression. Quadrupoles and sextupoles are employed in a bunch compressor one (BC1 design, in such a way that second order longitudinal dispersion of BC1 cancels the second order energy correlation in the electron beam. Start-to-end 6-D simulations are performed with all the collective effects included. Emittance growth in the horizontal plane due to coherent synchrotron radiation is investigated and minimized, to be on a similar level with the successfully operating Linac coherent light source (LCLS. At a FEL radiation wavelength of 0.15 nm, a saturation length of 40 meters can be achieved by employing an undulator with a period of 1.5 cm. Without tapering, a FEL radiation power above 10 GW is achieved with a photon pulse length of 50 fs, which is LCLS-like performance. The overall length of the accelerator plus undulator is around 250 meters which is much shorter than the LCLS length of 1230 meters. That makes it possible to build hard X-ray FEL in a laboratory with limited size.

  13. THE SPECTACULAR RADIO-NEAR-IR-X-RAY JET OF 3C 111: THE X-RAY EMISSION MECHANISM AND JET KINEMATICS

    Energy Technology Data Exchange (ETDEWEB)

    Clautice, Devon; Perlman, Eric S. [Department of Physics and Space Sciences, Florida Institute of Technology, 150 W. University Boulevard, Melbourne, FL 32901 (United States); Georganopoulos, Markos [Department of Physics, University of Maryland—Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Lister, Matthew L.; Hogan, Brandon [Department of Physics and Astronomy, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States); Tombesi, Francesco [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Cara, Mihai [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Marshall, Herman L. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Kazanas, Demos [NASA’s Goddard Space Flight Center, Astrophysics Science Division, Code 663, Greenbelt, MD 20771 (United States)

    2016-08-01

    Relativistic jets are the most energetic manifestation of the active galactic nucleus (AGN) phenomenon. AGN jets are observed from the radio through gamma-rays and carry copious amounts of matter and energy from the sub-parsec central regions out to the kiloparsec and often megaparsec scale galaxy and cluster environs. While most spatially resolved jets are seen in the radio, an increasing number have been discovered to emit in the optical/near-IR and/or X-ray bands. Here we discuss a spectacular example of this class, the 3C 111 jet, housed in one of the nearest, double-lobed FR II radio galaxies known. We discuss new, deep Chandra and Hubble Space Telescope ( HST ) observations that reveal both near-IR and X-ray emission from several components of the 3C 111 jet, as well as both the northern and southern hotspots. Important differences are seen between the morphologies in the radio, X-ray, and near-IR bands. The long (over 100 kpc on each side), straight nature of this jet makes it an excellent prototype for future, deep observations, as it is one of the longest such features seen in the radio, near-IR/optical, and X-ray bands. Several independent lines of evidence, including the X-ray and broadband spectral shape as well as the implied velocity of the approaching hotspot, lead us to strongly disfavor the EC/CMB model and instead favor a two-component synchrotron model to explain the observed X-ray emission for several jet components. Future observations with NuSTAR , HST , and Chandra will allow us to further constrain the emission mechanisms.

  14. Evidence for crustal low shear-wave speed in western Saudi Arabia from multi-scale fundamental-mode Rayleigh-wave group-velocity tomography

    KAUST Repository

    Tang, Zheng

    2018-05-15

    We investigate the crustal and upper-mantle shear-velocity structure of Saudi Arabia by fundamental-mode Rayleigh-wave group-velocity tomography and shear-wave velocity inversion. The seismic dataset is compiled using ∼140 stations of the Saudi National Seismic Network (SNSN) operated by the Saudi Geological Survey (SGS). We measure Rayleigh-wave group-velocities at periods of 8–40 s from regional earthquakes. After obtaining 1-D shear-wave velocity models by inverting group-velocities at each grid node, we construct a 3-D shear-velocity model for Saudi Arabia and adjacent regions by interpolating the 1-D models. Our 3-D model indicates significant lateral variations in crustal and lithospheric thickness, as well as in the shear-wave velocity over the study region. In particular, we identify zones of reduced shear-wave speed at crustal levels beneath the Cenozoic volcanic fields in the Arabian Shield. The inferred reductions of 2–5% in shear-wave speed may be interpreted as possibly indicating the presence of partial melts. However, their precise origin we can only speculate about. Our study also reveals an upper-mantle low velocity zone (LVZ) below the Arabian Shield, supporting the model of lateral mantle flow from the Afar plume. Further geophysical experiments are needed to confirm (or refute) the hypothesis that partial melts may exist below the Cenozoic volcanism in western Saudi Arabia, and to build a comprehensive geodynamic–geological model for the evolution and present state of the lithosphere of the Arabian Plate and the Red Sea.

  15. Evidence for crustal low shear-wave speed in western Saudi Arabia from multi-scale fundamental-mode Rayleigh-wave group-velocity tomography

    KAUST Repository

    Tang, Zheng; Mai, Paul Martin; Chang, Sung-Joon; Zahran, Hani

    2018-01-01

    We investigate the crustal and upper-mantle shear-velocity structure of Saudi Arabia by fundamental-mode Rayleigh-wave group-velocity tomography and shear-wave velocity inversion. The seismic dataset is compiled using ∼140 stations of the Saudi National Seismic Network (SNSN) operated by the Saudi Geological Survey (SGS). We measure Rayleigh-wave group-velocities at periods of 8–40 s from regional earthquakes. After obtaining 1-D shear-wave velocity models by inverting group-velocities at each grid node, we construct a 3-D shear-velocity model for Saudi Arabia and adjacent regions by interpolating the 1-D models. Our 3-D model indicates significant lateral variations in crustal and lithospheric thickness, as well as in the shear-wave velocity over the study region. In particular, we identify zones of reduced shear-wave speed at crustal levels beneath the Cenozoic volcanic fields in the Arabian Shield. The inferred reductions of 2–5% in shear-wave speed may be interpreted as possibly indicating the presence of partial melts. However, their precise origin we can only speculate about. Our study also reveals an upper-mantle low velocity zone (LVZ) below the Arabian Shield, supporting the model of lateral mantle flow from the Afar plume. Further geophysical experiments are needed to confirm (or refute) the hypothesis that partial melts may exist below the Cenozoic volcanism in western Saudi Arabia, and to build a comprehensive geodynamic–geological model for the evolution and present state of the lithosphere of the Arabian Plate and the Red Sea.

  16. Computational study of electronic, optical and thermoelectric properties of X3PbO (X = Ca, Sr, Ba) anti-perovskites

    Science.gov (United States)

    Hassan, M.; Arshad, I.; Mahmood, Q.

    2017-11-01

    We report the structural, electronic, optical and thermoelectric (TE) properties of X3PbO (X = Ca, Sr, Ba) anti-perovskites as a function of X cations belonging to the group IIA. The computations are done by using the most recently introduced modified Becke-Johnson potential. It has been observed that the cubic lattice constant increases as the cations change from Ca to Ba, consequently, the bulk modulus reduces. The bottom of conduction band shows strong hybridization between Pb-6p, O-2p and X-s states, in contrast, valence band maxima are mainly manufactured by Pb-6p states. The anti-perovskites exhibit narrow direct band gap that show an inverse relation to the static real dielectric constants that verifies Penn’s model. In addition, the X cations induced tuning of the absorption edge in the visible and the ultraviolet energy suggest optical device applications. The computed TE parameters have been found sensitive to the X cations and have been demonstrated to be best suited for the TE devices operating at high temperatures.

  17. Settling velocities in batch sedimentation

    International Nuclear Information System (INIS)

    Fricke, A.M.; Thompson, B.E.

    1982-10-01

    The sedimentation of mixtures containing one and two sizes of spherical particles (44 and 62 μm in diameter) was studied. Radioactive tracing with 57 Co was used to measure the settling velocities. The ratio of the settling velocity U of uniformly sized particles to the velocity predicted to Stokes' law U 0 was correlated to an expression of the form U/U 0 = epsilon/sup α/, where epsilon is the liquid volume fraction and α is an empirical constant, determined experimentally to be 4.85. No effect of viscosity on the ratio U/U 0 was observed as the viscosity of the liquid medium was varied from 1x10 -3 to 5x10 -3 Pa.s. The settling velocities of particles in a bimodal mixture were fit by the same correlation; the ratio U/U 0 was independent of the concentrations of different-sized particles

  18. Measuring Velocities in the Early Stage of an Eruption: Using “Overlappogram” Data from Hinode EIS

    Energy Technology Data Exchange (ETDEWEB)

    Harra, Louise K.; Matthews, Sarah; Culhane, J. Leonard; Woods, Magnus M. [UCL-Mullard Space Science Laboratory Holmbury St Mary, Dorking, Surrey, RH5 6NT (United Kingdom); Hara, Hirohisa [National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan); Doschek, George A.; Warren, Harry, E-mail: l.harra@ucl.ac.uk [Space Science Division, Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, DC 20375 (United States)

    2017-06-10

    In order to understand the onset phase of a solar eruption, plasma parameter measurements in the early phases are key to constraining models. There are two current instrument types that allow us to make such measurements: narrow-band imagers and spectrometers. In the former case, even narrow-band filters contain multiple emission lines, creating some temperature confusion. With imagers, however, rapid cadences are achievable and the field of view can be large. Velocities of the erupting structures can be measured by feature tracking. In the spectrometer case, slit spectrometers can provide spectrally pure images by “rastering” the slit to build up an image. This method provides limited temporal resolution, but the plasma parameters can be accurately measured, including velocities along the line of sight. Both methods have benefits and are often used in tandem. In this paper we demonstrate for the first time that data from the wide slot on the Hinode EUV Imaging Spectrometer, along with imaging data from AIA, can be used to deconvolve velocity information at the start of an eruption, providing line-of-sight velocities across an extended field of view. Using He ii 256 Å slot data at flare onset, we observe broadening or shift(s) of the emission line of up to ±280 km s{sup −1}. These are seen at different locations—the redshifted plasma is seen where the hard X-ray source is later seen (energy deposition site). In addition, blueshifted plasma shows the very early onset of the fast rise of the filament.

  19. Microscopic theory of longitudinal sound velocity in charge ordered manganites

    International Nuclear Information System (INIS)

    Rout, G C; Panda, S

    2009-01-01

    A microscopic theory of longitudinal sound velocity in a manganite system is reported here. The manganite system is described by a model Hamiltonian consisting of charge density wave (CDW) interaction in the e g band, an exchange interaction between spins of the itinerant e g band electrons and the core t 2g electrons, and the Heisenberg interaction of the core level spins. The magnetization and the CDW order parameters are considered within mean-field approximations. The phonon Green's function was calculated by Zubarev's technique and hence the longitudinal velocity of sound was finally calculated for the manganite system. The results show that the elastic spring involved in the velocity of sound exhibits strong stiffening in the CDW phase with a decrease in temperature as observed in experiments.

  20. Microscopic theory of longitudinal sound velocity in charge ordered manganites

    Energy Technology Data Exchange (ETDEWEB)

    Rout, G C [Condensed Matter Physics Group, PG Department of Applied Physics and Ballistics, FM University, Balasore 756 019 (India); Panda, S, E-mail: gcr@iopb.res.i [Trident Academy of Technology, F2/A, Chandaka Industrial Estate, Bhubaneswar 751 024 (India)

    2009-10-14

    A microscopic theory of longitudinal sound velocity in a manganite system is reported here. The manganite system is described by a model Hamiltonian consisting of charge density wave (CDW) interaction in the e{sub g} band, an exchange interaction between spins of the itinerant e{sub g} band electrons and the core t{sub 2g} electrons, and the Heisenberg interaction of the core level spins. The magnetization and the CDW order parameters are considered within mean-field approximations. The phonon Green's function was calculated by Zubarev's technique and hence the longitudinal velocity of sound was finally calculated for the manganite system. The results show that the elastic spring involved in the velocity of sound exhibits strong stiffening in the CDW phase with a decrease in temperature as observed in experiments.

  1. Band offsets in HfTiO/InGaZnO{sub 4} heterojunction determined by X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    He, G., E-mail: ganghe01@issp.ac.cn [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei 230601 (China); Chen, X.F. [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei 230601 (China); Lv, J.G., E-mail: jglv@hftc.edu.cn [School of Electronic and Information Engineering, Hefei Normal University, Hefei 230601 (China); Fang, Z.B., E-mail: csfzb@usx.edu.cn [Department of Physics, Shaoxing University, Shaoxing 312000 (China); Liu, Y.M.; Zhu, K.R.; Sun, Z.Q. [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei 230601 (China); Liu, M., E-mail: mliu@issp.ac.cn [Key Laboratory of Materials Physics, Anhui Key Laboratory of Nanomaterials and Nanostructure, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2015-09-05

    Highlights: • Band offsets in HfTiO/InGaZnO{sub 4} heterojunction were determined by XPS. • Valence band offset of HfTiO/IGZO heterojunction is determined to be 0.35 eV. • Conduction band offset of 1.61 eV is deduced for HfTiO/IGZO heterojunction. - Abstract: In current report, X-ray photoelectron spectroscopy has been pursued to obtain the valence band discontinuity (ΔE{sub v}) of sputter deposited HfTiO/InZnGaO{sub 4} (IGZO) heterostructures. A ΔE{sub v} value of 0.32 ± 0.1 eV was obtained by using the Ga 2p3/2, Zn 2p3/2, and In 3d5/2 energy levels as references. Taking into consideration the experimental band gaps of 5.35 eV and 3.39 eV for HfTiO and IGZO thin films measured by absorption method, respectively, this would result in a conduction band offset of 1.64 eV in this heterostructure.

  2. X-band ESR study on evaluation of radicals induced in pasteurized pepper

    International Nuclear Information System (INIS)

    Matsuura, Masaaki; Ogawa, Satoko; Ukai, Mitsuko; Oowada, Shigeru

    2007-01-01

    The radical properties of pasteurized pepper were investigated by means of X-band ESR spectroscopy. Pasteurization process was done by irradiation or steam. There were three radicals in the specimens before and after pasteurization. Upon irradiation a new radical was found. ESR peak intensity of specimen before and after parturition with steam was almost same level. Peak intensity of radiated pepper showed almost 4 times as compare with that of non treated pepper. Radical activity of the specimens after pasteurization showed almost same value. We concluded that radicals were induced by irradiation. But the radical activity was not changed before and after pasteurization. (author)

  3. X-Ray and Near-Infrared Spectroscopy of Dim X-Ray Point Sources Constituting the Galactic Ridge X-Ray Emission

    Directory of Open Access Journals (Sweden)

    Kumiko Morihana

    2014-12-01

    Full Text Available We present the results of X-ray and Near-Infrared observations of the Galactic Ridge X-ray Emission (GRXE. We extracted 2,002 X-ray point sources in the Chandra Bulge Field (l =0°.113, b = 1°.424 down to ~10-14.8 ergscm-2s-1 in 2-8 keV band with the longest observation (900 ks of the GRXE. Based on X-ray brightness and hardness, we classied the X-ray point sources into three groups: A (hard, B (soft and broad spectrum, and C (soft and peaked spectrum. In order to know populations of the X-ray point sources, we carried out NIR imaging and spectroscopy observation. We identied 11% of X-ray point sources with NIR and extracted NIR spectra for some of them. Based on X-ray and NIR properties, we concluded that non-thermal sources in the group A are mostly active galactic nuclei and the thermal sources are mostly white dwarf binaries such as cataclysmic variables (CVs and Pre-CVs. We concluded that the group B and C sources are X-ray active stars in flare and quiescence, respectively.

  4. Crystallographic Investigations into Properties of Acentric Hybrid Perovskite Single Crystals NH(CH3)3SnX3(X = Cl, Br)

    KAUST Repository

    Dang, Yangyang

    2016-10-11

    The hybrid perovskites with special optoelectronic properties have attracted more attention to the scientific and industrial applications. However, because of the toxicity and instability of lead complexes, there is interest in finding a nontoxic substitute for the lead in the halides perovskites and solving the ambiguous crystal structures and phase transition of NH(CH3)3SnX3 (X = Cl, Br). Here, we report the bulk crystal growths and different crystal morphologies of orthorhombic hybrid perovskites NH(CH3)3SnX3 (X = Cl, Br) in an ambient atmosphere by bottom-seeded solution growth (BSSG) method. More importantly, detailed structural determination and refinements, phase transition, band gap, band structure calculations, nonlinear optical (NLO) properties, XPS, thermal properties, and stability of NH(CH3)3SnX3 (X = Cl, Br) single crystals are demonstrated. NH(CH3)3SnCl3 single crystal undergoes reversible structural transformation from orthorhombic space group Cmc21 (no. 36) to monoclinic space group Cc (no. 9) and NH(CH3)3SnBr3 belongs to the orthorhombic space group Pna21 (no. 33) by DSC, single-crystal X-ray diffraction and temperature-dependent SHG measurements, which clarify the former results. These results should pave the way for further studies of these materials in optoelectronics.

  5. Valence band structure of binary chalcogenide vitreous semiconductors by high-resolution XPS

    International Nuclear Information System (INIS)

    Kozyukhin, S.; Golovchak, R.; Kovalskiy, A.; Shpotyuk, O.; Jain, H.

    2011-01-01

    High-resolution X-ray photoelectron spectroscopy (XPS) is used to study regularities in the formation of valence band electronic structure in binary As x Se 100−x , As x S 100−x , Ge x Se 100−x and Ge x S 100−x chalcogenide vitreous semiconductors. It is shown that the highest occupied energetic states in the valence band of these materials are formed by lone pair electrons of chalcogen atoms, which play dominant role in the formation of valence band electronic structure of chalcogen-rich glasses. A well-expressed contribution from chalcogen bonding p electrons and more deep s orbitals are also recorded in the experimental valence band XPS spectra. Compositional dependences of the observed bands are qualitatively analyzed from structural and compositional points of view.

  6. Valence band structure of binary chalcogenide vitreous semiconductors by high-resolution XPS

    Energy Technology Data Exchange (ETDEWEB)

    Kozyukhin, S., E-mail: sergkoz@igic.ras.ru [Russian Academy of Science, Institute of General and Inorganic Chemistry (Russian Federation); Golovchak, R. [Lviv Scientific Research Institute of Materials of SRC ' Carat' (Ukraine); Kovalskiy, A. [Lehigh University, Department of Materials Science and Engineering (United States); Shpotyuk, O. [Lviv Scientific Research Institute of Materials of SRC ' Carat' (Ukraine); Jain, H. [Lehigh University, Department of Materials Science and Engineering (United States)

    2011-04-15

    High-resolution X-ray photoelectron spectroscopy (XPS) is used to study regularities in the formation of valence band electronic structure in binary As{sub x}Se{sub 100-x}, As{sub x}S{sub 100-x}, Ge{sub x}Se{sub 100-x} and Ge{sub x}S{sub 100-x} chalcogenide vitreous semiconductors. It is shown that the highest occupied energetic states in the valence band of these materials are formed by lone pair electrons of chalcogen atoms, which play dominant role in the formation of valence band electronic structure of chalcogen-rich glasses. A well-expressed contribution from chalcogen bonding p electrons and more deep s orbitals are also recorded in the experimental valence band XPS spectra. Compositional dependences of the observed bands are qualitatively analyzed from structural and compositional points of view.

  7. Sr hexaferrite/Ni ferrite nanocomposites: Magnetic behavior and microwave absorbing properties in the X-band

    Energy Technology Data Exchange (ETDEWEB)

    Jacobo, Silvia E. [Facultad de Ingeniería, Universidad de Buenos Aires, LAFMACEL-INTECIN, Paseo Colón 850, C1063EHA Buenos Aires (Argentina); Bercoff, Paula G., E-mail: bercoff@famaf.unc.edu.ar [Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba, IFEG, CONICET, Ciudad Universitaria, X5000HUA Córdoba (Argentina); Herme, Carlos A. [Facultad de Ingeniería, Universidad de Buenos Aires, LAFMACEL-INTECIN, Paseo Colón 850, C1063EHA Buenos Aires (Argentina); Vives, Leandro A. [División Antenas, Instituto de Investigaciones Científicas para la Defensa CITEDEF, Ministerio de Defensa, San Juan Bautista de La Salle 4397, Villa Martelli, B1603ALO Buenos Aires (Argentina)

    2015-05-01

    Nickel ferrite nanoparticles were synthesized by a self-combustion method over nanocrystalline powders of Nd–Co substituted strontium hexaferrite with nominal composition Sr{sub 0.5}Nd{sub 0.5}Co{sub 0.5}Fe{sub 10.5}O{sub 19}, at different mass relations. The samples were structurally characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). The M vs. H loops of the composites were determined with a vibrating sample magnetometer (VSM) and the interaction with the X-band microwave radiation of the nanocomposites dispersed in epoxy resin was measured with a vector network analyzer (VNA). The hysteresis loops showed strong exchange-coupling between the two magnetic phases for the 30:70 and 50:50 Sr{sub 0.5}Co{sub 0.5}Nd{sub 0.5}Fe{sub 10.5}O{sub 19}/NiFe{sub 2}O{sub 4} nanocomposites, while a weak interaction was observed for the 70:30 mass ratio. The nanocomposite with an equal amount of hard and soft phase shows the highest performance both in reflectivity and in bandwidth, reaching a maximum in reflectivity of −34.4 dB at 11.1 GHz while the bandwidth below −10 dB is 3.5 GHz. - Highlights: • Sr{sub 0.5}Co{sub 0.5}Nd{sub 0.5}Fe{sub 10.5}O{sub 19}/NiFe{sub 2}O{sub 4} nanocomposites were synthesized at different mass ratios. • The systems were structurally and magnetically characterized. • The X-band microwave radiation of the composites was evaluated. • Enhancement in reflectivity is related to exchange interaction between hard and soft phases.

  8. Structural and magnetic properties of La{sup 3+} substituted barium−natural nanoferrites as microwave absorber in X-band

    Energy Technology Data Exchange (ETDEWEB)

    Widanarto, W., E-mail: wahyu.widanarto@unsoed.ac.id [Department of Physics, FMIPA, Universitas Jenderal Soedirman, Jl. dr. Soeparno 61 Purwokerto 53123 (Indonesia); Amirudin, F. [Department of Physics, FMIPA, Universitas Jenderal Soedirman, Jl. dr. Soeparno 61 Purwokerto 53123 (Indonesia); Ghoshal, S.K. [Department of Physics, AMORG, Faculty of Science, Universiti Teknologi Malaysia, Johor Bahru, Skudai 81310 (Malaysia); Effendi, M.; Cahyanto, W.T. [Department of Physics, FMIPA, Universitas Jenderal Soedirman, Jl. dr. Soeparno 61 Purwokerto 53123 (Indonesia)

    2017-03-15

    Selection of proper microwave absorbers in the X-band is vital to prevent the interference issues that often damage devices and cause signal degradation. In this spirit, we prepared three La{sup 3+} substituted barium-natural nanoferrites (BNFs) samples with chemical composition of BaO:(x)La{sub 2}O{sub 3}:(6-x)Fe{sub 2}O{sub 3} (x=0, 0.1, 0.2 in mol) via solid-state reaction route. Synthesized samples were characterized via SEM, XRD, VSM, and VNA measurements to determine the La{sup 3+} ions concentration dependent variation in the structural, magnetic and microwave absorption properties. Transmission/reflection line (TRL) method was used to evaluate the samples reflection loss. La{sup 3+} free samples sintered at 1100 °C revealed hexagonal BaFe{sub 12}O{sub 19} and rhombohedral Fe{sub 2}O{sub 3} phases. SEM images displayed the growth of new particle with the average size of 0.2 – 0.8 µm as filler in BNFs. Furthermore, an incorporation of La{sup 3+} into the BNF system manifested the emergence of new BaLa{sub 2}Fe{sub 2}O{sub 7} tetragonal crystal phase. The average crystallite size of BNF was found to decrease with increasing La{sup 3+} ion concentrations. Conversely, substitution of La{sup 3+} in the BNF caused insignificant changes in the magnetic properties, the real part of the relative permittivity and the natural resonance frequency. Meanwhile, a reasonable shift in the microwave frequency absorption and enhancement in the reflection loss was evidenced due to the inclusion of La{sup 3+}. BNF sample containing 0.2 mol La{sub 2}O{sub 3} exhibited a saturation magnetization and magnetic field anisotropy of 19.02 and 0.36 T, respectively, where the maximum reflection loss is discerned to be −26.61 dB at 10.87 GHz with 1.25 GHz bandwidth. This new class of ferrites may be prospective for microwave absorber in the X-band. - Highlights: • La{sup 3+} ions substitution into barium–natural nanoferrite via the solid-state reaction. • Influence of La{sup 3

  9. InAs quantum dot growth on AlxGa1−xAs by metalorganic vapor phase epitaxy for intermediate band solar cells

    International Nuclear Information System (INIS)

    Jakomin, R.; Kawabata, R. M. S.; Souza, P. L.; Mourão, R. T.; Pires, M. P.; Micha, D. N.; Xie, H.; Fischer, A. M.; Ponce, F. A.

    2014-01-01

    InAs quantum dot multilayers have been grown using Al x Ga 1−x As spacers with dimensions and compositions near the theoretical values for optimized efficiencies in intermediate band photovoltaic cells. Using an aluminium composition of x = 0.3 and InAs dot vertical dimensions of 5 nm, transitions to an intermediate band with energy close to the ideal theoretical value have been obtained. Optimum size uniformity and density have been achieved by capping the quantum dots with GaAs following the indium-flush method. This approach has also resulted in minimization of crystalline defects in the epilayer structure

  10. Amphibious Shear Velocity Structure of the Cascadia Subduction Zone

    Science.gov (United States)

    Janiszewski, H. A.; Gaherty, J. B.; Abers, G. A.; Gao, H.

    2017-12-01

    The amphibious Cascadia Initiative crosses the coastline of the Cascadia subduction zone (CSZ) deploying seismometers from the Juan de Fuca ridge offshore to beyond the volcanic arc onshore. This allows unprecedented seismic imaging of the CSZ, enabling examination of both the evolution of the Juan de Fuca plate prior to and during subduction as well as the along strike variability of the subduction system. Here we present new results from an amphibious shear velocity model for the crust and upper mantle across the Cascadia subduction zone. The primary data used in this inversion are surface-wave phase velocities derived from ambient-noise Rayleigh-wave data in the 10 - 20 s period band, and teleseismic earthquake Rayleigh wave phase velocities in the 20 - 160 s period band. Phase velocity maps from these data reflect major tectonic structures including the transition from oceanic to continental lithosphere, Juan de Fuca lithosphere that is faster than observations in the Pacific for oceanic crust of its age, slow velocities associated with the accretionary prism, the front of the fast subducting slab, and the Cascades volcanic arc which is associated with slower velocities in the south than in the north. Crustal structures are constrained by receiver functions in the offshore forearc and onshore regions, and by active source constraints on the Juan de Fuca plate prior to subduction. The shear-wave velocities are interpreted in their relationships to temperature, presence of melt or hydrous alteration, and compositional variation of the CSZ.

  11. Facile growth and composition-dependent photocatalytic activity of flowerlike BiOCl{sub 1−x}Br{sub x} hierarchical microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Qin; Guo, Yingna [School of Chemistry, Northeast Normal University, Changchun 130024 (China); Zhou, Dandan; Yang, Yuxin [School of Environment, Northeast Normal University, Changchun, 130117 (China); Guo, Yihang, E-mail: guoyh@nenu.edu.cn [School of Environment, Northeast Normal University, Changchun, 130117 (China)

    2016-12-30

    Highlights: • Flowerlike BiOCl{sub 1−x}Br{sub x} hierarchical microspheres were prepared by solvothermal route. • BiOCl{sub 1−x}Br{sub x} microspheres exhibited composition-dependent photocatalytic activity. • Band gap and potential of valence band dominated the photoactivity of BiOCl{sub 1−x}Br{sub x}. • BiOCl{sub 1−x}Br{sub x} microspheres can be reused at least four times without obvious activity loss. - Abstract: A group of nanosheet-assembled three-dimensional BiOCl{sub 1−x}Br{sub x} hierarchical microspheres (x = 0, 0.3, 0.4, 0.5, 0.7, 0.8 and 1.0) with layered tetragonal crystal phase were prepared by 2-methoxyethanol-assisted solvothermal route and using ionic liquids as both halogen sources and structure-directing agent. By the combination of the results including XRD, XPS and UV–vis/DR spectra, lattice substitution of halogen atoms each other and then formation of BiOCl{sub 1−x}Br{sub x} solid solution was evidenced. Additionally, the BiOCl{sub 1−x}Br{sub x} microspheres exhibited interesting composition-dependent band gaps. The simulated sunlight and visible-light photocatalytic properties including degradation, mineralization and reusability of the BiOCl{sub 1−x}Br{sub x} microspheres were evaluated by selecting p-nitrophenol (PNP) and tetrabromobisphenol-A (TBBPA) as the target pollutant compounds, finding that the balance between the suitable band gap and adequate potential of the valence band in BiOCl{sub 1−x}Br{sub x} crystals dominated their photocatalytic activity. Additionally, the BiOCl{sub 1−x}Br{sub x} microspheres with advantages such as enhanced photon utilization efficiency, larger BET surface area and favorable (110) exposed reactive surface gave the positive influence on their photocatalytic activity. Based on the results of photoelectrochemistry experiment and indirect chemical probe testing, direct {sup •} O{sub 2}{sup −} and h{sub VB}{sup +} photooxidation for the decomposition of PNP or TBBPA was

  12. Anomalous signature splitting of the πh11/2direct x νi13/2 band in A-160 odd-odd nuclei

    International Nuclear Information System (INIS)

    Yang Chunxiang; Zhou Hongyu

    2003-01-01

    Systematic features of anomalous signature splitting of the πh 11/2 direct x νi 13/2 band in A-160 odd-odd nuclei have been investigated. It is shown that the mechanism of anomalous signature splitting is similar to that of the normal signature splitting which is essentially caused by the Coriolis mixing of Ω=1/2 components into the nuclear wavefunction and the anomalous splitting in signature is mainly caused by the definition. The extensively observed anomalous signature splitting in this band might be an indication that the interaction between the h 11/2 proton and the i 13/2 neutron cannot be neglected. The new observation of high- and low-K bands based on the same πh 11/2 direct x νi 13/2 configuration in 164 Tm is also discussed

  13. Characteristic wave velocities in spherical electromagnetic cloaks

    International Nuclear Information System (INIS)

    Yaghjian, A D; Maci, S; Martini, E

    2009-01-01

    We investigate the characteristic wave velocities in spherical electromagnetic cloaks, namely, phase, ray, group and energy-transport velocities. After deriving explicit expressions for the phase and ray velocities (the latter defined as the phase velocity along the direction of the Poynting vector), special attention is given to the determination of group and energy-transport velocities, because a cursory application of conventional formulae for local group and energy-transport velocities can lead to a discrepancy between these velocities if the permittivity and permeability dyadics are not equal over a frequency range about the center frequency. In contrast, a general theorem can be proven from Maxwell's equations that the local group and energy-transport velocities are equal in linear, lossless, frequency dispersive, source-free bianisotropic material. This apparent paradox is explained by showing that the local fields of the spherical cloak uncouple into an E wave and an H wave, each with its own group and energy-transport velocities, and that the group and energy-transport velocities of either the E wave or the H wave are equal and thus satisfy the general theorem.

  14. Incorporation of ester groups into low band-gap diketopyrrolopyrrole containing polymers for solar cell applications

    DEFF Research Database (Denmark)

    Hu, Xiaolian; Zuo, Lijian; Fu, Weifei

    2012-01-01

    To increase the open circuit voltage (VOC) of polymer solar cells based on diketopyrrolopyrrole (DPP) containing polymers, the weakly electron-withdrawing thiophene-3,4-dicarboxylate unit was introduced into the polymer backbone. Two ester group functionalized DPP containing polymers, PCTDPP...... with a random structure and PDCTDPP with a regular structure, were designed and synthesized by the Stille coupling reaction. The resulting copolymers exhibit broad and strong absorption bands from 350 to 1000 nm with low optical band gaps below 1.40 eV. Through cyclic voltammetry measurements, it is found...

  15. Wire measurement of impedance of an X-band accelerating structure

    CERN Document Server

    Baboi, N; Dolgashev, V A; Jones, R M; Lewandowski, J R; Tantawi, S G; Wang, J W

    2004-01-01

    Several tens of thousands of accelerator structures will be needed for the next generation of linear collders known as the GLC/NLC (Global Linear Collider/Next Linear Collider). To prevent the beam being driven into a disruptive BBU (Beam Break Up) mode or at the very least, the emittance being signifcantly diluted, it is important to damp down the wakefield left by driving bunches to a manageable level. Manufacturing errors and errors in design need to be measurable and compared with predictions. We develop a circuit model of wire-loaded X-band accelerator structures. This enables the wakefield (the inverse transform of the beam impedance) to be readily computed and compared with the wire measurement. We apply this circuit model to the latest series of accelerating for the GLC/NLC. This circuit model is based upon the single-cell model developed in [1] extended here to complete, multi-cell structures.

  16. Strain and electric field induced metallization in the GaX (X = N, P, As & Sb) monolayer

    Science.gov (United States)

    Bahuguna, Bhagwati Prasad; Saini, L. K.; Sharma, Rajesh O.; Tiwari, Brajesh

    2018-05-01

    We investigate the strain and electric field dependent electronic properties of two dimensional Ga-based group III-V monolayer from the first-principles approach within density functional theory. The energy bandgap of GaX monolayer increases upto the certain value of compressive strain and then decreases. On the other hand, the energy bandgap of GaX monolayer is monotonically decreased with increasing tensile strain and become metallic at the higher value. Furthermore, the perpendicular electric field decreases the energy band gap of unstrained GaX monolayer and shows semiconductor to metal transition. These results suggest that the nature of energy bands and value of energy bandgap in GaX monolayer can be tuned by the biaxial mechanical strain or perpendicular electrical field. Additionally, we have also studied the optical response of unstrained GaX monolayer in term of optical conductivity. These findings may provide valuable information to develop the Ga-based optoelectronic devices and further the understanding of the GaX monolayer.

  17. High-gradient experiment on X-band disk-loaded structures

    International Nuclear Information System (INIS)

    Higo, T.; Taniuchi, T.; Yamamoto, M.; Odagiri, J.; Tokumoto, S.; Mizuno, H.; Takata, K.; Wilson, I.; Wuensch, W.

    1993-09-01

    The high-gradient performance of two travelling-wave X-band accelerating structures 20 cm long has been studied. One of the structures, KEK, was conditioned up to an average accelerating gradient (Eav) of 68 MV/m in 600 hours, while the other, CERN, reached 85 MV/m in 50 hours. In the latter case the maximum output power was fed from the SLED system and the maximum field inside the structure was 138 MV/m. This maximum level was limited by the available power from the klystron. Operation at the Eav=50 MV/m level was found to be stable for both structures. The associated dark current at this level was less than a few μA for CERN but 20 to 30 μA for KEK. Since the two electrical designs are almost the same the difference in dark current must be attributed to the difference in the two fabrication techniques. Modified Fowler-Northeim plots of downstream dark current showed a change of slope, a kink, around 50 to 60 MV/m above which the field enhancement factor was substantially increased. (author)

  18. Precision Magnet Measurements for X-Band Accelerator Quadrupole Triplets

    Energy Technology Data Exchange (ETDEWEB)

    Marsh, R A; Anderson, S G; Armstrong, J P

    2012-05-16

    An X-band test station is being developed at LLNL to investigate accelerator optimization for future upgrades to mono-energetic gamma-ray (MEGa-Ray) technology at LLNL. Beamline magnets will include an emittance compensation solenoid, windowpane steering dipoles, and quadrupole magnets. Demanding tolerances have been placed on the alignment of these magnets, which directly affects the electron bunch beam quality. A magnet mapping system has been established at LLNL in order to ensure the delivered magnets match their field specification, and the mountings are aligned and capable of reaching the specified alignment tolerances. The magnet measurement system will be described which uses a 3-axis Lakeshore gauss probe mounted on a 3-axis translation stage. Alignment accuracy and precision will be discussed, as well as centering measurements and analysis. The dependence on data analysis over direct multi-pole measurement allows a significant improvement in useful alignment information. Detailed analysis of measurements on the beamline quadrupoles will be discussed, including multi-pole content both from alignment of the magnets, and the intrinsic level of multi-pole magnetic field.

  19. Synthesis of compositionally controllable Cu{sub 2}(Sn{sub 1−x}Ge{sub x})S{sub 3} nanocrystals with tunable band gaps

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Qingshuang, E-mail: lqs671@163.com [Jilin University, State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry (China)

    2016-06-15

    In this work, we show that compositionally controlled Cu{sub 2}(Sn{sub 1–x}Ge{sub x})S{sub 3} nanocrystals can be successfully synthesized by the hot-injection method through careful tuning the Ge/(Sn+Ge) precursor ratio. The band gaps of the resultant nanocrystals are demonstrated to be linearly tuned from 1.45 to 2.33 eV by adjusting the composition parameter x of the Ge/(Sn+Ge) ratio from 0.0 to 1.0. The crystalline structures of the resultant NCs have been studied by the X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), select area electron diffraction (SAED), and Raman spectroscopy. A ligand exchange procedure is further performed to replace the native ligands on the surface of the NCs with sulfur ions. The photoresponsive behavior indicates the potential use of as-prepared Cu{sub 2}(Sn{sub 1–x}Ge{sub x})S{sub 3} nanocrystals in solar energy conversion systems. The synthesis of compositionally controlled Cu{sub 2}(Sn{sub 1–x}Ge{sub x})S{sub 3} nanocrystals reported herein provides a way for probing the effect of Ge inclusion in the Cu-Sn-S system thin films.

  20. Vibration Stabilization of a Mechanical Model of a X-Band Linear Collider Final Focus Magnet

    CERN Document Server

    Frisch, J; Decker, V; Hendrickson, L; Markiewicz, T W; Partridge, R; Seryi, Andrei

    2004-01-01

    The small beam sizes at the interaction point of a X-band linear collider require mechanical stabilization of the final focus magnets at the nanometer level. While passive systems provide adequate performance at many potential sites, active mechanical stabilization is useful if the natural or cultural ground vibration is higher than expected. A mechanical model of a room temperature linear collider final focus magnet has been constructed and actively stabilized with an accelerometer based system.

  1. Vibration Stabilization of a Mechanical Model of a X-Band Linear Collider Final Focus Magnet

    International Nuclear Information System (INIS)

    Frisch, Josef; Chang, Allison; Decker, Valentin; Doyle, Eric; Eriksson, Leif; Hendrickson, Linda; Himel, Thomas; Markiewicz, Thomas; Partridge, Richard; Seryi, Andrei; SLAC

    2006-01-01

    The small beam sizes at the interaction point of a X-band linear collider require mechanical stabilization of the final focus magnets at the nanometer level. While passive systems provide adequate performance at many potential sites, active mechanical stabilization is useful if the natural or cultural ground vibration is higher than expected. A mechanical model of a room temperature linear collider final focus magnet has been constructed and actively stabilized with an accelerometer based system

  2. Electron Band Alignment at Interfaces of Semiconductors with Insulating Oxides: An Internal Photoemission Study

    Directory of Open Access Journals (Sweden)

    Valeri V. Afanas'ev

    2014-01-01

    Full Text Available Evolution of the electron energy band alignment at interfaces between different semiconductors and wide-gap oxide insulators is examined using the internal photoemission spectroscopy, which is based on observations of optically-induced electron (or hole transitions across the semiconductor/insulator barrier. Interfaces of various semiconductors ranging from the conventional silicon to the high-mobility Ge-based (Ge, Si1-xGex, Ge1-xSnx and AIIIBV group (GaAs, InxGa1-xAs, InAs, GaP, InP, GaSb, InSb materials were studied revealing several general trends in the evolution of band offsets. It is found that in the oxides of metals with cation radii larger than ≈0.7 Å, the oxide valence band top remains nearly at the same energy (±0.2 eV irrespective of the cation sort. Using this result, it becomes possible to predict the interface band alignment between oxides and semiconductors as well as between dissimilar insulating oxides on the basis of the oxide bandgap width which are also affected by crystallization. By contrast, oxides of light elements, for example, Be, Mg, Al, Si, and Sc exhibit significant shifts of the valence band top. General trends in band lineup variations caused by a change in the composition of semiconductor photoemission material are also revealed.

  3. Einstein coefficients for rotational lines of the (0,0) band of the NO A2sigma(+)-X2Pi system

    Science.gov (United States)

    Reisel, John R.; Carter, Campbell D.; Laurendeau, Normand M.

    1992-01-01

    A summary of the spectroscopic equations necessary for prediction of the molecular transition energies and the Einstein A and B coefficients for rovibronic lines of the gamma(0,0) band of nitric oxide (NO) is presented. The calculated molecular transition energies are all within 0.57/cm of published experimental values; in addition, over 95 percent of the calculated energies give agreement with measured results within 0.25/cm. Einstein coefficients are calculated from the band A00 value and the known Hoenl-London factors and are tabulated for individual rovibronic transitions in the NO A2sigma(+)-X2Pi(0,0) band.

  4. Unidentified bands lambda lambda 6830, 7088 in symbiotic stars

    Energy Technology Data Exchange (ETDEWEB)

    Allen, D A [Anglo-Australian Observatory, Epping (Australia)

    1980-01-01

    About 60 stars are known which show broad emission bands centred at wavelengths of 6830 and 7088 A. The stars are all classified as symbiotic, since they combine high-excitation emission and M-type absorption spectra. From the behaviour of the bands in the evolution of slow novae as they approach the symbiotic phase, and from the occurrence of the bands in stars of different excitation, it is concluded that the ions responsible have ionization potentials near 100 eV. The similarity of behaviour and profile of the two suggests that both arise in the same species. No suitable identification appears possible at this time, because of the lack of data on highly ionized species. Arguments are presented which narrow the range of possibilities, the most notable argument being the absence of O VI emission. It is suggested that Fe VII or Fe VI may be responsible. In particular, it is recommended that transitions from the z/sup 3/P/sup 0/ and z/sup 1/F/sup 0/ levels of Fe VII be examined in detail. The differing, and time-varying profiles of the 6830 and 7088 bands in the stars observed are best explained in terms of velocity broadening. Velocities in excess of 1000 km s/sup -1/ are present. Rotation is a more credible form of the mass motion than expansion, because of the tendency to double profiles in these bands. If rotation is responsible, these velocities imply that the objects central to the emission nebulae are more compact than main sequence stars.

  5. Parameterization of L-, C- and X-band Radiometer-based Soil Moisture Retrieval Algorithm Using In-situ Validation Sites

    Science.gov (United States)

    Gao, Y.; Colliander, A.; Burgin, M. S.; Walker, J. P.; Chae, C. S.; Dinnat, E.; Cosh, M. H.; Caldwell, T. G.

    2017-12-01

    Passive microwave remote sensing has become an important technique for global soil moisture estimation over the past three decades. A number of missions carrying sensors at different frequencies that are capable for soil moisture retrieval have been launched. Among them, there are Japan Aerospace Exploration Agency's (JAXA's) Advanced Microwave Scanning Radiometer-EOS (AMSR-E) launched in May 2002 on the National Aeronautics and Space Administration (NASA) Aqua satellite (ceased operation in October 2011), European Space Agency's (ESA's) Soil Moisture and Ocean Salinity (SMOS) mission launched in November 2009, JAXA's Advanced Microwave Scanning Radiometer 2 (AMSR2) onboard the GCOM-W satellite launched in May 2012, and NASA's Soil Moisture Active Passive (SMAP) mission launched in January 2015. Therefore, there is an opportunity to develop a consistent inter-calibrated long-term soil moisture data record based on the availability of these four missions. This study focuses on the parametrization of the tau-omega model at L-, C- and X-band using the brightness temperature (TB) observations from the four missions and the in-situ soil moisture and soil temperature data from core validation sites across various landcover types. The same ancillary data sets as the SMAP baseline algorithm are applied for retrieval at different frequencies. Preliminary comparison of SMAP and AMSR2 TB observations against forward-simulated TB at the Yanco site in Australia showed a generally good agreement with each other and higher correlation for the vertical polarization (R=0.96 for L-band and 0.93 for C- and X-band). Simultaneous calibrations of the vegetation parameter b and roughness parameter h at both horizontal and vertical polarizations are also performed. Finally, a set of model parameters for successfully retrieving soil moisture at different validation sites at L-, C- and X-band respectively are presented. The research described in this paper is supported by the Jet Propulsion

  6. Wind Speed Retrieval by Means of X-Band Cosmo-Skymed SAR Data with Application to Coastel Circulation Modeling

    Science.gov (United States)

    Montuori, Antonio; de Ruggiero, Paola; Migliaccio, Maurizio; Pierini, Stefano

    2012-03-01

    In this paper, the capabilities of X-band COSMOSkyMed SAR data are investigated for both wind speed estimation purposes and for the improvement of coastal circulation modeling. The data set consists of 60 X-band Level 1B Multi-Look Ground Detected ScanSAR HugeRegion COSMO-SkyMed SAR data, gathered in the Southern Tyrrhenian Sea during the summer and winter seasons of 2010. Wind speed is estimated by means of a SAR wind speed retrieval based on the azimuth cut-off procedure. Wind direction is provided by means of a SAR retrieval approach based on Discrete Wavelet Transform. After comparison with the provided ground truth data, SAR-derived wind fields and ECMWF data are used to construct a blended wind product regularly sampled in both space and time. The resulting wind field will be used to force the Princeton Ocean Model, which has been implemented in a Southern Tyrrhenian Sea coastal area to simulate wind-driven costal circulation processes.

  7. Shear wave velocity structure of northern and North-Eastern Ethiopia

    International Nuclear Information System (INIS)

    Kebede, F.; Mammo, T.; Panza, G.F.; Vuan, A.; Costa, G.

    1995-10-01

    The non-linear inversion technique known as hedgehog is utilized to define the average crustal structure of North and North-Eastern Ethiopia. To accomplish the task a two dimensional frequency-time analysis is performed to obtain Rayleigh wave group velocity dispersion curves. Six earthquakes recorded by the broad-band digital seismograph installed at the Geophysical Observatory of Addis Ababa University are utilized. The crustal structure between the Gulf of Tadjura (western Gulf of Aden) and Addis Ababa crossing southern Afar (path I) can be approximated by a total thickness of about 22 km with average S-wave velocity in the range 2.3 - 3.9 km/s. The crust-mantle transition is poorly developed at greater depths and the shear wave velocity ranges from 4.0 km/s to 4.3 km/s. If the effect of the plateau part is taken into account the average total crustal thickness is found to be less than 18 km and the average S-wave velocity varies in the range 2.4 - 3.9 km/s. The low shear wave velocity under the Afar crust is consistent with the result of other geophysical studies. For path II, which passes through the border of the Western Ethiopian plateau, the average crustal structure is found to be approximated by a thickness of about 40 km and average S-wave velocity between 3.0 km/s and 3.9 km/s. The crust overlies a lithospheric mantle with a shear wave velocity in the range 4.1-4.4 km/s. (author). 37 refs, 11 figs, 4 tabs

  8. ANALYSIS OF DEBRIS FLOW DISASTER DUE TO HEAVY RAIN BY X-BAND MP RADAR DATA

    Directory of Open Access Journals (Sweden)

    M. Nishio

    2016-06-01

    Full Text Available On August 20 of 2014, Hiroshima City (Japan was struck by local heavy rain from an autumnal rain front. The resultant debris flow disaster claimed 75 victims and destroyed many buildings. From 1:30 am to 4:30 am on August 20, the accumulated rainfall in Hiroshima City exceeded 200 mm. Serious damage occurred in the Asakita and Asaminami wards of Hiroshima City. As a disaster prevention measure, local heavy rain (localized torrential rains is usually observed by the Automated Meteorological Data Acquisition System (AMeDAS operated by the Japan Meteorological Agency (JMA and by the C-band radar operated by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT of Japan, with spatial resolutions of 2.5 km and 1 km, respectively. The new X-band MP radar system enables more detailed rainfall observations than the C-band radar. In fact, this radar can observe local rainfall throughout Japan in near-real time over a minimum mesh size of 250 m. A fine-scale accumulated rainfall monitoring system is crucial for disaster prevention, and potential disasters can be alerted by the hazard levels of the accumulated rainfall.

  9. Multi-shell spherical GaAs /AlxGa1-x As quantum dot shells-size distribution as a mechanism to generate intermediate band energy levels

    Science.gov (United States)

    Rodríguez-Magdaleno, K. A.; Pérez-Álvarez, R.; Martínez-Orozco, J. C.; Pernas-Salomón, R.

    2017-04-01

    In this work the generation of an intermediate band of energy levels from multi-shell spherical GaAs /AlxGa1-x As quantum dot shells-size distribution is reported. Within the effective mass approximation the electronic structure of a GaAs spherical quantum-dot surrounded by one, two and three shells is studied in detail using a numerically stable transfer matrix method. We found that a shells-size distribution characterized by continuously wider GaAs domains is a suitable mechanism to generate the intermediate band whose width is also dependent on the Aluminium concentration x. Our results suggest that this effective mechanism can be used for the design of wider intermediate band than reported in other quantum systems with possible solar cells enhanced performance.

  10. Dynamics of Impurity and Valence Bands in Ga1-xMnzAs Within the Dynamical Mean Field Approximation

    Energy Technology Data Exchange (ETDEWEB)

    Majidi, M. A. [University of Cincinnati; Moreno, Juana [University of North Dakota, Grand Forks; Jarrell, Mark [University of Cincinnati; Fishman, Randy Scott [ORNL; Aryanpour, K. A. [University of California, Davis

    2006-01-01

    We calculate the density-of-states and the spectral function of Ga{sub 1-x}Mn{sub x}As within the dynamical mean-field approximation. Our model includes the competing effects of the strong spin-orbit coupling on the J=3/2 GaAs hole bands and the exchange interaction between the magnetic ions and the itinerant holes. We study the quasiparticle and impurity bands in the paramagnetic and ferromagnetic phases for different values of impurity-hole coupling J{sub c} at a Mn doping of x=0.05. By analyzing the anisotropic angular distribution of the impurity band carriers at T=0, we conclude that the carrier polarization is optimal when the carriers move along the direction parallel to the average magnetization.

  11. Valley-dependent band structure and valley polarization in periodically modulated graphene

    Science.gov (United States)

    Lu, Wei-Tao

    2016-08-01

    The valley-dependent energy band and transport property of graphene under a periodic magnetic-strained field are studied, where the time-reversal symmetry is broken and the valley degeneracy is lifted. The considered superlattice is composed of two different barriers, providing more degrees of freedom for engineering the electronic structure. The electrons near the K and K' valleys are dominated by different effective superlattices. It is found that the energy bands for both valleys are symmetric with respect to ky=-(AM+ξ AS) /4 under the symmetric superlattices. More finite-energy Dirac points, more prominent collimation behavior, and new crossing points are found for K' valley. The degenerate miniband near the K valley splits into two subminibands and produces a new band gap under the asymmetric superlattices. The velocity for the K' valley is greatly renormalized compared with the K valley, and so we can achieve a finite velocity for the K valley while the velocity for the K' valley is zero. Especially, the miniband and band gap could be manipulated independently, leading to an increase of the conductance. The characteristics of the band structure are reflected in the transmission spectra. The Dirac points and the crossing points appear as pronounced peaks in transmission. A remarkable valley polarization is obtained which is robust to the disorder and can be controlled by the strain, the period, and the voltage.

  12. Super-Eddington accretion on to the neutron star NGC 7793 P13: Broad-band X-ray spectroscopy and ultraluminous X-ray sources

    Science.gov (United States)

    Walton, D. J.; Fürst, F.; Harrison, F. A.; Stern, D.; Bachetti, M.; Barret, D.; Brightman, M.; Fabian, A. C.; Middleton, M. J.; Ptak, A.; Tao, L.

    2018-02-01

    We present a detailed, broad-band X-ray spectral analysis of the ultraluminous X-ray source (ULX) pulsar NGC 7793 P13, a known super-Eddington source, utilizing data from the XMM-Newton, NuSTAR and Chandra observatories. The broad-band XMM-Newton+NuSTAR spectrum of P13 is qualitatively similar to the rest of the ULX sample with broad-band coverage, suggesting that additional ULXs in the known population may host neutron star accretors. Through time-averaged, phase-resolved and multi-epoch studies, we find that two non-pulsed thermal blackbody components with temperatures ∼0.5 and 1.5 keV are required to fit the data below 10 keV, in addition to a third continuum component which extends to higher energies and is associated with the pulsed emission from the accretion column. The characteristic radii of the thermal components appear to be comparable, and are too large to be associated with the neutron star itself, so the need for two components likely indicates the accretion flow outside the magnetosphere is complex. We suggest a scenario in which the thick inner disc expected for super-Eddington accretion begins to form, but is terminated by the neutron star's magnetic field soon after its onset, implying a limit of B ≲ 6 × 1012 G for the dipolar component of the central neutron star's magnetic field. Evidence of similar termination of the disc in other sources may offer a further means of identifying additional neutron star ULXs. Finally, we examine the spectrum exhibited by P13 during one of its unusual 'off' states. These data require both a hard power-law component, suggesting residual accretion on to the neutron star, and emission from a thermal plasma, which we argue is likely associated with the P13 system.

  13. The energy band structure of A{sub x}Fe{sub 2}Se{sub 2} (A = K, Rb) superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Zabidi, Noriza A. [Physics Department, Centre for Defence Foundation Studies, Universiti Pertahanan Nasional Malaysia, Kuala Lumpur 59200 (Malaysia); Azhan, Muhd. Z. [Defence Science Department, Faculty of Defence Science and Technology, Universiti Pertahanan Nasional Malaysia, Kuala Lumpur 59200 (Malaysia); Rosli, A. N. [Faculty of Science and Technology, Universiti Sains Islam Malaysia, Nilai 71800, Negeri Sembilan (Malaysia); Shrivastava, Keshav N. [School of Physics, University of Hyderabad, Hyderabad 500046 (India)

    2014-03-05

    We study the band structure of antiferromagnetic A{sub x}Fe{sub 2}Se{sub 2} (A = K, Rb) superconductors by using first-principles electronic structure calculations which is density functional theory. In the vicinity of iron-vacancy, we identify the valence electrons of A{sub x}Fe{sub 2}Se{sub 2} will be filled up to the Fermi level and no semiconducting gap is observed. Hence, the A{sub x}Fe{sub 2}Se{sub 2} is a metallic instead of semiconducting which leads to superconductivity in the orbital-selective Mott phase. Similarly, there is non-vanishing density of states at the Fermi level.

  14. Semiclassical three-valley Monte Carlo simulation analysis of steady-state and transient electron transport within bulk InAsxP1-x, InAs and InP

    Directory of Open Access Journals (Sweden)

    Hadi Arabshahi

    2010-04-01

    Full Text Available We have studied how electrons, initially in thermal equilibrium, drift under the action of an applied electric field within bulk zincblende InAsxP1-x, InAs and InP. Calculations are made using a non-parabolic effective-mass energy band model. Monte Carlo simulation includes all of the major scattering mechanisms. The band parameters used in the simulation are extracted from optimised pseudo-potential band calculations to ensure excellent agreement with experimental information and ab-initio band models. The effects of alloy scattering on the electron transport physics are examined. For all materials, it is found that electron velocity overshoot only occurs when the electric field is increased to a value above a certain critical field, unique to each material. This critical field is strongly dependent on the material parameters. Transient velocity overshoot has also been simulated, with the sudden application of fields up to 1600 kVm-1, appropriate to the gate-drain fields expected within an operational field-effect transistor. The electron drift velocity relaxes to the saturation value of about 1.5105 ms-1 within 4 pico-seconds for all crystal structures. The steady-state and transient velocity overshoot characteristics are in fair agreement with other recent calculations.

  15. Study of the Mg incorporation in CdTe for developing wide band gap Cd{sub 1-x}Mg{sub x}Te thin films for possible use as top-cell absorber in a tandem solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Omar S. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, 62580 Temixco, Morelos (Mexico); Universidad Politecnica del Estado de Guerrero, Comunidad de Puente Campuzano, C.P. 40325 Taxco de Alarcon, Guerrero (Mexico); Millan, Aduljay Remolina [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, 62580 Temixco, Morelos (Mexico); Huerta, L.; Santana, G. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico. C.P 04510 Mexico D.F. (Mexico); Mathews, N.R.; Ramon-Garcia, M.L.; Morales, Erik R. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, 62580 Temixco, Morelos (Mexico); Mathew, X., E-mail: xm@cie.unam.mx [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, 62580 Temixco, Morelos (Mexico)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Thin films of Cd{sub 1-x}Mg{sub x}Te with high spatial uniformity and band gap in the range of 1.6-1.96 eV were deposited by vacuum co-evaporation of CdTe and Mg. Black-Right-Pointing-Pointer Obtained Cd{sub 1-x}Mg{sub x}Te films have the structural characteristics of the CdTe, evidence of the change in atomic scattering due to incorporation of Mg was observed. Black-Right-Pointing-Pointer XRD and XPS data confirmed the incorporation of Mg in the lattice of CdTe. Black-Right-Pointing-Pointer SEM images revealed the impact of Mg incorporation on the morphology of the films, the changes in grain size and grain morphology are noticeable. - Abstract: Thin films of Cd{sub 1-x}Mg{sub x}Te with band gap in the range of 1.6-1.96 eV were deposited by vacuum co-evaporation of CdTe and Mg on glass substrates heated at 300 Degree-Sign C. Different experimental techniques such as XRD, UV-vis spectroscopy, SEM, and XPS were used to study the effect of Mg incorporation into the lattice of CdTe. The band gap of the films showed a clear tendency to increase as the Mg content in the film is increased. The Cd{sub 1-x}Mg{sub x}Te films maintain all the structural characteristics of the CdTe, however, diminishing of intensity for the XRD patterns is observed due to both change in preferential orientation and change in atomic scattering due to the incorporation of Mg. SEM images showed significant evidences of morphological changes due to the presence of Mg. XRD, UV-vis spectroscopy, and XPS data confirmed the incorporation of Mg in the lattice of CdTe. The significant increase in band gap of CdTe due to incorporation of Mg suggests that the Cd{sub 1-x}Mg{sub x}Te thin film is a candidate material to use as absorber layer in the top-cell of a tandem solar cell.

  16. A Compact 5 MeV S-Band Electron Linac Based X-Ray Source for Industrial Radiography

    CERN Document Server

    Auditore, Lucrezia; De Pasquale, Domenico; Emanuele, Umberto; Italiano, Antonio; Trifirò, Antonio; Trimarchi, Marina

    2005-01-01

    A compact and reliable X-ray source, based on a 5 MeV, 1 kW, S-band electron linac, has been set up at the Dipartimento di Fisica, Universit\\'a di Messina. This source, coupled with a GOS scintillator screen and a CCD camera, represents an innovative transportable system for industrial radiography and X-ray tomography. Optimization of the parameters influencing the e-gamma conversion and the X-ray beam characteristics have been studied by means of the MCNP-4C2 code. The converter choice is the result of the study of the e-gamma conversion performances for different materials and materials thicknesses. Also the converter position with respect to the linac exit window was studied. The chosen converter consists in a Ta-Cu target inserted close to the linac window. The Cu layer acts as a filter both on the electrons from the source and on the low energy X-rays. The X-ray beam angular profile was studied by means of GafChromic films with and without collimation. In the final source project, a collimation system pr...

  17. Galaxies in the X-ray Band

    Science.gov (United States)

    Hornschemeier, Ann

    2008-01-01

    This talk will provide a brief review of progress on X-ray emission from normal (non-AGN) galaxy populations, including important constraints on the evolution of accreting binary populations over important cosmological timescales. We will also look to the future, anticipating constraints from near-term imaging hard X-ray missions such as NuSTAR, Simbol-X and NeXT and then the longer-term prospects for studying galaxies with the Generation-X mission.

  18. Infrared Absorption Band Assignment in Benzanilide and Some of its p

    African Journals Online (AJOL)

    MBI

    2014-07-10

    Jul 10, 2014 ... benzanilide and its p-methyl, p-chloro, p-bromo, p-carboxy, and p-nitro derivatives. Out of the six characteristic. Amide Bands ... (where X = H, methyl, chloro, bromo, carboxyl, and nitro groups). The assignment has been made ..... ion, alkali metal benzoate and salicylates. Spectrochimica Acta 17:486- 502.

  19. Signature inversion in πh{sub 11/2} x νi{sub 13/2} band of {sup 152}Eu and {sup 154,156}Tb

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sushil [Akal University, Department of Physics, Talwandi Sabo (India); Maharishi Markandeshwar University, Department of Physics, Mullana (India); Singh, Sukhjeet [Akal University, Department of Physics, Talwandi Sabo (India); Sharma, Vandana; Sharma, J.K. [Maharishi Markandeshwar University, Department of Physics, Mullana (India)

    2017-04-15

    The phenomenon of signature inversion observed in the πh{sub 11/2} x νi{sub 13/2} band of {sup 152}Eu and {sup 156}Tb nuclides is revisited through the axially symmetric two quasiparticle plus rotor model approach. The magnitude of experimentally observed signature splitting and point of signature inversion, which could not be explicitly reproduced in the earlier calculations, is successfully reproduced in the present study. Some of the critical issues, such as violation of the well-established Gallagher Moszkowski (GM) rule for eight GM doublets appearing in the basis space of earlier calculations of {sup 152}Eu and {sup 156}Tb, are fixed and also the ambiguity regarding spin assignment to this band observed in {sup 156}Tb is resolved. These calculations are further extended to the same band (πh{sub 11/2} x νi{sub 13/2}) observed in {sup 154}Tb nuclide and signature inversion observed in this band is successfully reproduced. (orig.)

  20. Band alignment and charge transfer predictions of ZnO/ZnX (X = S, Se or Te) interfaces applied to solar cells: a PBE+U theoretical study.

    Science.gov (United States)

    Flores, Efracio Mamani; Gouvea, Rogério Almeida; Piotrowski, Maurício Jeomar; Moreira, Mário Lucio

    2018-02-14

    The engineering of semiconductor materials for the development of solar cells is of great importance today. Two topics are considered to be of critical importance for the efficiency of Grätzel-type solar cells, the efficiency of charge separation and the efficiency of charge carrier transfer. Thus, one research focus is the combination of semiconductor materials with the aim of reducing charge recombination, which occurs by spatial charge separation. From an experimental point of view, the combining of materials can be achieved by decorating a core with a shell of another material resulting in a core-shell system, which allows control of the desired photoelectronic properties. In this context, a computational simulation is mandatory for the atomistic understanding of possible semiconductor combinations and for the prediction of their properties. Considering the construction of ZnO/ZnX (X = S, Se or Te) interfaces, we seek to investigate the electronic influence of the shell (ZnX) on the core (ZnO) and, consequently, find out which of the interfaces would present the appropriate properties for (Grätzel-type) solar cell applications. To perform this study, we have employed density functional theory (DFT) calculations, considering the Perdew-Burke-Ernzerhof (PBE) functional. However, it is well-known that plain DFT fails to describe strong electronic correlated materials where, in general, an underestimation of the band gap is obtained. Thus, to obtain the correct description of the electronic properties, a Hubbard correction was employed, i.e. PBE+U calculations. The PBE+U methodology provided the correct electronic structure properties for bulk ZnO in good agreement with experimental values (99.4%). The ZnO/ZnX interfaces were built and were composed of six ZnO layers and two ZnX layers, which represents the decoration process. The core-shell band gap was 2.2 eV for ZnO/ZnS, ∼1.71 eV for ZnO/ZnSe and ∼0.95 eV for ZnO/ZnTe, which also exhibited a type-II band

  1. GALAXIES IN X-RAY GROUPS. III. SATELLITE COLOR AND MORPHOLOGY TRANSFORMATIONS

    Energy Technology Data Exchange (ETDEWEB)

    George, Matthew R.; Ma, Chung-Pei [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Bundy, Kevin; Leauthaud, Alexie; Vulcani, Benedetta [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), Todai Institutes for Advanced Study, University of Tokyo, Kashiwa 277-8583 (Japan); Tinker, Jeremy [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Wechsler, Risa H. [Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Finoguenov, Alexis, E-mail: mgeorge@astro.berkeley.edu [Department of Physics, University of Helsinki, Gustaf Haellstroemin katu 2a, FI-00014 Helsinki (Finland)

    2013-06-20

    While the star formation rates and morphologies of galaxies have long been known to correlate with their local environment, the process by which these correlations are generated is not well understood. Galaxy groups are thought to play an important role in shaping the physical properties of galaxies before entering massive clusters at low redshift, and transformations of satellite galaxies likely dominate the buildup of local environmental correlations. To illuminate the physical processes that shape galaxy evolution in dense environments, we study a sample of 116 X-ray selected galaxy groups at z = 0.2-1 with halo masses of 10{sup 13}-10{sup 14} M{sub Sun} and centroids determined with weak lensing. We analyze morphologies based on Hubble Space Telescope imaging and colors determined from 31 photometric bands for a stellar mass-limited population of 923 satellite galaxies and a comparison sample of 16,644 field galaxies. Controlling for variations in stellar mass across environments, we find significant trends in the colors and morphologies of satellite galaxies with group-centric distance and across cosmic time. Specifically at low stellar mass (log (M{sub *}/M{sub Sun }) = 9.8-10.3), the fraction of disk-dominated star-forming galaxies declines from >50% among field galaxies to <20% among satellites near the centers of groups. This decline is accompanied by a rise in quenched galaxies with intermediate bulge+disk morphologies, and only a weak increase in red bulge-dominated systems. These results show that both color and morphology are influenced by a galaxy's location within a group halo. We suggest that strangulation and disk fading alone are insufficient to explain the observed morphological dependence on environment, and that galaxy mergers or close tidal encounters must play a role in building up the population of quenched galaxies with bulges seen in dense environments at low redshift.

  2. GALAXIES IN X-RAY GROUPS. III. SATELLITE COLOR AND MORPHOLOGY TRANSFORMATIONS

    International Nuclear Information System (INIS)

    George, Matthew R.; Ma, Chung-Pei; Bundy, Kevin; Leauthaud, Alexie; Vulcani, Benedetta; Tinker, Jeremy; Wechsler, Risa H.; Finoguenov, Alexis

    2013-01-01

    While the star formation rates and morphologies of galaxies have long been known to correlate with their local environment, the process by which these correlations are generated is not well understood. Galaxy groups are thought to play an important role in shaping the physical properties of galaxies before entering massive clusters at low redshift, and transformations of satellite galaxies likely dominate the buildup of local environmental correlations. To illuminate the physical processes that shape galaxy evolution in dense environments, we study a sample of 116 X-ray selected galaxy groups at z = 0.2-1 with halo masses of 10 13 -10 14 M ☉ and centroids determined with weak lensing. We analyze morphologies based on Hubble Space Telescope imaging and colors determined from 31 photometric bands for a stellar mass-limited population of 923 satellite galaxies and a comparison sample of 16,644 field galaxies. Controlling for variations in stellar mass across environments, we find significant trends in the colors and morphologies of satellite galaxies with group-centric distance and across cosmic time. Specifically at low stellar mass (log (M * /M ☉ ) = 9.8-10.3), the fraction of disk-dominated star-forming galaxies declines from >50% among field galaxies to <20% among satellites near the centers of groups. This decline is accompanied by a rise in quenched galaxies with intermediate bulge+disk morphologies, and only a weak increase in red bulge-dominated systems. These results show that both color and morphology are influenced by a galaxy's location within a group halo. We suggest that strangulation and disk fading alone are insufficient to explain the observed morphological dependence on environment, and that galaxy mergers or close tidal encounters must play a role in building up the population of quenched galaxies with bulges seen in dense environments at low redshift.

  3. An X- and Q-band Fe3+ EPR study of nanoparticles of magnetic semiconductor Zn1-xFexO

    Science.gov (United States)

    Misra, Sushil K.; Andronenko, S. I.; Thurber, A.; Punnoose, A.; Nalepa, A.

    2014-08-01

    EPR studies on two types of nanoparticles of Fe3+ doped, 0.1-10%, ZnO, NL and QJ, prepared using similar chemical hydrolysis methods, in diethylene glycol, and in denatured ethanol solutions, respectively, were carried out at X-band (~9.5 GHz) at 77 K and at Q-band (~34.0 GHz) at 10, 80, and 295 K. To interpret the experimental results, EPR spectra were simulated by exact diagonalization of the spin-Hamiltonian matrix to identify the Fe ions at different magnetically active sites in these samples. The simulation for NL samples revealed that they contained (i) Fe3+ ions, which substituted for Zn ions, the zero-field splitting (ZFS) parameter which has a large distribution over the sample due to oxygen vacancies in the second coordination sphere; (ii) EPR signal from surface oxygen defects; and (iii) ferromagnetically (FM) coupled Fe ions with concentration of Fe more than 1%. The EPR spectra for QJ samples are very different from those for NL samples, exhibiting only rather intense FM EPR lines. The FM and EPR spectra in NL and/or QJ samples are found to vary strongly with differences in the surface morphology of nanoparticles.

  4. Review of wide band-gap semiconductors technology

    Directory of Open Access Journals (Sweden)

    Jin Haiwei

    2016-01-01

    Full Text Available Silicon carbide (SiC and gallium nitride (GaN are typical representative of the wide band-gap semiconductor material, which is also known as third-generation semiconductor materials. Compared with the conventional semiconductor silicon (Si or gallium arsenide (GaAs, wide band-gap semiconductor has the wide band gap, high saturated drift velocity, high critical breakdown field and other advantages; it is a highly desirable semiconductor material applied under the case of high-power, high-temperature, high-frequency, anti-radiation environment. These advantages of wide band-gap devices make them a hot spot of semiconductor technology research in various countries. This article describes the research agenda of United States and European in this area, focusing on the recent developments of the wide band-gap technology in the US and Europe, summed up the facing challenge of the wide band-gap technology.

  5. Rayleigh wave group-velocity across the Dominican Republic and Puerto Rico from ambient noise tomography

    Science.gov (United States)

    Quiros, D.; Pulliam, J.; Polanco Rivera, E.; Huerfano Moreno, V. A.

    2017-12-01

    The eastern North America-Caribbean (NA-CAR) plate boundary near the islands of Hispaniola (which is comprised of the Dominican Republic and Haiti) and Puerto Rico is a complex transition zone in which strain is accommodated by two transform fault systems and oblique subduction. In 2013, scientists from Baylor University, the Autonomous University of Santo Domingo, and the Puerto Rico Seismic Network deployed 16 broadband stations on the Dominican Republic to expand the local permanent network. The goal of the Greater Antilles Seismic Program (GrASP) is to combine its data with that from permanent networks in Puerto Rico, Haiti, Cuba, the Cayman Islands, and Jamaica to develop a better understanding of the crust and upper mantle structure in the Northeastern Caribbean (Greater Antilles). One important goal of GrASP is to develop robust velocity models that can be used to improve earthquake location and seismic hazard efforts. In this study, we focus on obtaining Rayleigh wave group velocity maps from ambient noise tomography. By cross-correlating ambient seismic noise recorded at 53 stations between 2010 to present, we obtain Green's functions between 1165 pairs of stations. From these, we obtain dispersion curves by the application of FTAN methods with phase-matched filtering. Selection criteria depend on the signal-to-noise ratio and seasonal variability, with further filtering done by rejecting velocities incompatible with maps produced from overdamped tomographic inversions. Preliminary dispersion maps show strong correlations with large-scale geological and tectonic features for periods between 5 - 20 s, such as the Cordillera Central in both the Dominican Republic and Puerto Rico, the Mona Passage, and the NA-CAR subduction zone. Ongoing efforts focus on including shorter periods in Puerto Rico as its denser station distribution could allow us to retrieve higher resolution group velocity maps.

  6. Band Alignment at GaN/Single-Layer WSe2 Interface

    KAUST Repository

    Tangi, Malleswararao

    2017-02-21

    We study the band discontinuity at the GaN/single-layer (SL) WSe2 heterointerface. The GaN thin layer is epitaxially grown by molecular beam epitaxy on chemically vapor deposited SL-WSe2/c-sapphire. We confirm that the WSe2 was formed as an SL from structural and optical analyses using atomic force microscopy, scanning transmission electron microscopy, micro-Raman, absorbance, and microphotoluminescence spectra. The determination of band offset parameters at the GaN/SL-WSe2 heterojunction is obtained by high-resolution X-ray photoelectron spectroscopy, electron affinities, and the electronic bandgap values of SL-WSe2 and GaN. The valence band and conduction band offset values are determined to be 2.25 ± 0.15 and 0.80 ± 0.15 eV, respectively, with type II band alignment. The band alignment parameters determined here provide a route toward the integration of group III nitride semiconducting materials with transition metal dichalcogenides (TMDs) for designing and modeling of their heterojunction-based electronic and optoelectronic devices.

  7. Band Alignment at GaN/Single-Layer WSe2 Interface

    KAUST Repository

    Tangi, Malleswararao; Mishra, Pawan; Tseng, Chien-Chih; Ng, Tien Khee; Hedhili, Mohamed N.; Anjum, Dalaver H.; Alias, Mohd Sharizal; Wei, Nini; Li, Lain-Jong; Ooi, Boon S.

    2017-01-01

    We study the band discontinuity at the GaN/single-layer (SL) WSe2 heterointerface. The GaN thin layer is epitaxially grown by molecular beam epitaxy on chemically vapor deposited SL-WSe2/c-sapphire. We confirm that the WSe2 was formed as an SL from structural and optical analyses using atomic force microscopy, scanning transmission electron microscopy, micro-Raman, absorbance, and microphotoluminescence spectra. The determination of band offset parameters at the GaN/SL-WSe2 heterojunction is obtained by high-resolution X-ray photoelectron spectroscopy, electron affinities, and the electronic bandgap values of SL-WSe2 and GaN. The valence band and conduction band offset values are determined to be 2.25 ± 0.15 and 0.80 ± 0.15 eV, respectively, with type II band alignment. The band alignment parameters determined here provide a route toward the integration of group III nitride semiconducting materials with transition metal dichalcogenides (TMDs) for designing and modeling of their heterojunction-based electronic and optoelectronic devices.

  8. Radial velocity observations of VB10

    Science.gov (United States)

    Deshpande, R.; Martin, E.; Zapatero Osorio, M. R.; Del Burgo, C.; Rodler, F.; Montgomery, M. M.

    2011-07-01

    VB 10 is the smallest star known to harbor a planet according to the recent astrometric study of Pravdo & Shaklan [1]. Here we present near-infrared (J-band) radial velocity of VB 10 performed from high resolution (R~20,000) spectroscopy (NIRSPEC/KECK II). Our results [2] suggest radial velocity variability with amplitude of ~1 km/s, a result that is consistent with the presence of a massive planet companion around VB10 as found via long-term astrometric monitoring of the star by Pravdo & Shaklan. Employing an entirely different technique we verify the results of Pravdo & Shaklan.

  9. Electronic properties and bonding in Zr Hx thin films investigated by valence-band x-ray photoelectron spectroscopy

    Science.gov (United States)

    Magnuson, Martin; Schmidt, Susann; Hultman, Lars; Högberg, Hans

    2017-11-01

    The electronic structure and chemical bonding in reactively magnetron sputtered Zr Hx (x =0.15 , 0.30, 1.16) thin films with oxygen content as low as 0.2 at.% are investigated by 4d valence band, shallow 4p core-level, and 3d core-level x-ray photoelectron spectroscopy. With increasing hydrogen content, we observe significant reduction of the 4d valence states close to the Fermi level as a result of redistribution of intensity toward the H 1s-Zr 4d hybridization region at ˜6 eV below the Fermi level. For low hydrogen content (x =0.15 , 0.30), the films consist of a superposition of hexagonal closest-packed metal (α phase) and understoichiometric δ -Zr Hx (Ca F2 -type structure) phases, while for x =1.16 , the films form single-phase Zr Hx that largely resembles that of stoichiometric δ -Zr H2 phase. We show that the cubic δ -Zr Hx phase is metastable as thin film up to x =1.16 , while for higher H contents the structure is predicted to be tetragonally distorted. For the investigated Zr H1.16 film, we find chemical shifts of 0.68 and 0.51 eV toward higher binding energies for the Zr 4 p3 /2 and 3 d5 /2 peak positions, respectively. Compared to the Zr metal binding energies of 27.26 and 178.87 eV, this signifies a charge transfer from Zr to H atoms. The change in the electronic structure, spectral line shapes, and chemical shifts as a function of hydrogen content is discussed in relation to the charge transfer from Zr to H that affects the conductivity by charge redistribution in the valence band.

  10. Theoretical optoelectronic analysis of intermediate-band photovoltaic material based on ZnY1−xOx (Y = S, Se, Te) semiconductors by first-principles calculations

    International Nuclear Information System (INIS)

    Wu Kong-Ping; Zhou Meng-Ran; Huang You-Rui; Gu Shu-Lin; Ye Jian-Dong; Zhu Shun-Ming; Zhang Rong; Zheng You-Dou; Tang Kun

    2013-01-01

    The structural, energetic, and electronic properties of lattice highly mismatched ZnY 1−x O x (Y = S, Se, Te) ternary alloys with dilute O concentrations are calculated from first principles within the density functional theory. We demonstrate the formation of an isolated intermediate electronic band structure through diluted O-substitute in zinc-blende ZnY (Y = S, Se, Te) at octahedral sites in a semiconductor by the calculations of density of states (DOS), leading to a significant absorption below the band gap of the parent semiconductor and an enhancement of the optical absorption in the whole energy range of the solar spectrum. It is found that the intermediate band states should be described as a result of the coupling between impurity O 2p states with the conduction band states. Moreover, the intermediate bands (IBs) in ZnTeO show high stabilization with the change of O concentration resulting from the largest electronegativity difference between O and Te compared with in the other ZnSO and ZnSeO. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  11. Kinetic and kinematic differences between squats performed with and without elastic bands.

    Science.gov (United States)

    Israetel, Michael A; McBride, Jeffrey M; Nuzzo, James L; Skinner, Jared W; Dayne, Andrea M

    2010-01-01

    The purpose of this investigation was to compare kinetic and kinematic variables between squats performed with and without elastic bands equalized for total work. Ten recreationally weight trained males completed 1 set of 5 squats without (Wht) and with (Band) elastic bands as resistance. Squats were completed while standing on a force platform with bar displacement measured using 2 potentiometers. Electromyography (EMG) was obtained from the vastus lateralis. Average force-time, velocity-time, power-time, and EMG-time graphs were generated and statistically analyzed for mean differences in values between the 2 conditions during the eccentric and concentric phases. The Band condition resulted in significantly higher forces in comparison to the Wht condition during the first 25% of the eccentric phase and the last 10% of the concentric phase (p squats equalized for total work with and without elastic bands significantly alter the force-time, power-time, velocity-time, and EMG-time curves associated with the movements. Specifically, elastic bands seem to increase force, power, and muscle activity during the early portions of the eccentric phase and latter portions of the concentric phase.

  12. Measurement of the valence band-offset in a PbSe/ZnO heterojunction by x-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Li Lin; Qiu Jijun; Weng Binbin; Yuan Zijian; Shi Zhisheng [School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019 (United States); Li Xiaomin; Gan Xiaoyan [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Sellers, Ian R. [Deparment of Physics, University of Oklahoma, Norman, Oklahoma 73019 (United States)

    2012-12-24

    A heterojunction of PbSe/ZnO has been grown by molecular beam epitaxy. X-ray photoelectron spectroscopy was used to directly measure the valence-band offset (VBO) of the heterojunction. The VBO, {Delta}E{sub V}, was determined as 2.51 {+-} 0.05 eV using the Pb 4p{sup 3/2} and Zn 2p{sup 3/2} core levels as a reference. The conduction-band offset, {Delta}E{sub C}, was, therefore, determined to be 0.59 {+-} 0.05 eV based on the above {Delta}E{sub V} value. This analysis indicates that the PbSe/ZnO heterojunction forms a type I (Straddling Gap) heterostructure.

  13. X-band 5-bit MMIC phase shifter with GaN HEMT technology

    Science.gov (United States)

    Sun, Pengpeng; Liu, Hui; Zhang, Zongjing; Geng, Miao; Zhang, Rong; Luo, Weijun

    2017-10-01

    The design approach and performance of a 5-bit digital phase shifter implemented with 0.25 μm GaN HEMT technology for X-band phased arrays are described. The switched filter and high-pass/low-pass networks are proposed in this article. For all 32 states of the 5-bit phase shifter, the RMS phase error less than 5.5°, RMS amplitude error less than 0.8 dB, insertion loss less than 12 dB and input/output return loss less than 8.5 dB are obtained overall 8-12 GHz. The continuous wave power capability is also measured, and a typical input RF P1dB data of 32 dBm is achieved at 8 GHz.

  14. X-ray photoelectron spectroscopy investigations of band offsets in Ga0.02Zn0.98O/ZnO heterojunction for UV photodetectors

    Science.gov (United States)

    Singh, Karmvir; Rawal, Ishpal; Punia, Rajesh; Dhar, Rakesh

    2017-10-01

    Here, we report the valence and conduction band offset measurements in pure ZnO and the Ga0.02Zn0.98O/ZnO heterojunction by X-Ray photoelectron spectroscopy studies for UV photodetector applications. For detailed investigations on the band offsets and UV photodetection behavior of Ga0.02Zn0.98O/ZnO heterostructures, thin films of pristine ZnO, Ga-doped ZnO (Ga0.02Zn0.98O), and heterostructures of Ga-doped ZnO with ZnO (Ga0.02Zn0.98O/ZnO) were deposited using a pulsed laser deposition technique. The deposited thin films were characterized by X-ray diffraction, atomic force microscopy, and UV-Vis spectroscopy. X-ray photoelectron spectroscopy studies were carried out on all the thin films for the investigation of valence and conduction band offsets. The valence band was found to be shifted by 0.28 eV, while the conduction band has a shifting of -0.272 eV in the Ga0.02Zn0.98O/ZnO heterojunction as compared to pristine ZnO thin films. All the three samples were analyzed for photoconduction behavior under UVA light of the intensity of 3.3 mW/cm2, and it was observed that the photoresponse of pristine ZnO (19.75%) was found to increase with 2 wt. % doping of Ga (22.62%) and heterostructured thin films (29.10%). The mechanism of UV photodetection in the deposited samples has been discussed in detail, and the interaction of chemisorbed oxygen on the ZnO surface with holes generated by UV light exposure has been the observed mechanism for the change in electrical conductivity responsible for UV photoresponse on the present deposited ZnO films.

  15. Stark Interference of Electric and Magnetic Dipole Transitions in the A-X Band of OH.

    Science.gov (United States)

    Schewe, H Christian; Zhang, Dongdong; Meijer, Gerard; Field, Robert W; Sartakov, Boris G; Groenenboom, Gerrit C; van der Avoird, Ad; Vanhaecke, Nicolas

    2016-04-15

    An experimental method is demonstrated that allows determination of the ratio between the electric (E1) and magnetic (M1) transition dipole moments in the A-X band of OH, including their relative sign. Although the transition strengths differ by more than 3 orders of magnitude, the measured M1-to-E1 ratio agrees with the ratio of the ab initio calculated values to within 3%. The relative sign is found to be negative, also in agreement with theory.

  16. A high power cross-field amplifier at X-Band

    International Nuclear Information System (INIS)

    Eppley, K.; Feinstein, J.; Ko, K.; Kroll, N.; Lee, T.; Nelson, E.

    1991-05-01

    A high power cross-field amplifier is under development at SLAC with the objective of providing sufficient peak power to feed a section of an X-Band (11.424 GHz) accelerator without the need for pulse compression. The CFA being designed employs a conventional distributed secondary emission cathode but a novel anode structure which consists of an array of vane resonators alternatively coupled to a rectangular waveguide. The waveguide impedance (width) is tapered linearly from input to output so as to provide a constant RF voltage at the vane tips, leading to uniform power generation along the structure. Nominal design for this tube calls for 300 MW output power, 20 dB gain, DC voltage 142 KV, magnetic field 5 KG, anode-cathode gap 3.6 mm and total interaction length of about 60 cm. These specifications have been supported by computer simulations of both the RF slow wave structure as well as the electron space charge wave interaction. We have used ARGUS to model the cold circuit properties and CONDOR to model the electronic power conversion. An efficiency of 60 percent can be expected. We will discuss the details of the design effort. 5 refs., 6 figs

  17. Band alignment in ZnSe/Zn1-x-yCdxMnySe quantum-well structures

    International Nuclear Information System (INIS)

    Yu, W.Y.; Salib, M.S.; Petrou, A.; Jonker, B.T.; Warnock, J.

    1997-01-01

    We present a magneto-optical study of ZnSe/Zn 1-x-y Cd x Mn y Se quantum-well structures in which a suitable choice of the Cd composition leads to a system that is type I at zero magnetic field. When a magnetic field is applied perpendicular to the layers of the structure, the band edges split in such a way as to make the upper σ - (1/2, t 3/2) exciton transition type II, while the ground state σ + (-1/2, -3/2) exciton component remains type I at all field values. This alignment reduces the probability for carrier relaxation from the higher-energy exciton component and opens the possibility of hole-spin population inversion via optical pumping. copyright 1997 The American Physical Society

  18. Temporal Variability in Seismic Velocity at the Salton Sea Geothermal Field

    Science.gov (United States)

    Taira, T.; Nayak, A.; Brenguier, F.

    2015-12-01

    We characterize the temporal variability of ambient noise wavefield and search for velocity changes associated with activities of the geothermal energy development at the Salton Sea Geothermal Field. The noise cross-correlations (NCFs) are computed for ~6 years of continuous three-component seismic data (December 2007 through January 2014) collected at 8 sites from the CalEnergy Subnetwork (EN network) with MSNoise software (Lecocq et al., 2014, SRL). All seismic data are downloaded from the Southern California Earthquake Data Center. Velocity changes (dv/v) are obtained by measuring time delay between 5-day stacks of NCFs and the reference NCF (average over the entire 6 year period). The time history of dv/v is determined by averaging dv/v measurements over all station/channel pairs (252 combinations). Our preliminary dv/v measurement suggests a gradual increase in dv/v over the 6-year period in a frequency range of 0.5-8.0 Hz. The resultant increase rate of velocity is about 0.01%/year. We also explore the frequency-dependent velocity change at the 5 different frequency bands (0.5-2.0 Hz, 0.75-3.0 Hz, 1.0-4.0 Hz, 1.5-6.0 Hz, and 2.0-8.0 Hz) and find that the level of this long-term dv/v variability is increased with increase of frequency (i.e., the highest increase rate of ~0.15%/year at the 0.5-2.0 Hz band). This result suggests that the velocity changes were mostly occurred in a depth of ~500 m assuming that the coda parts of NCFs (~10-40 s depending on station distances) are predominantly composed of scattered surface waves, with the SoCal velocity model (Dreger and Helmberger, 1993, JGR). No clear seasonal variation of dv/v is observed in the frequency band of 0.5-8.0 Hz.

  19. Proceedings of the 4th KEK mechanical engineering workshop. Research and development on the technology of the X-band accelerator fabrication

    International Nuclear Information System (INIS)

    Ueno, Kenji

    2003-10-01

    The fourth KEK Mechanical Engineering Workshop was held on April 17, 2003. The main subject was ''The Research and Development on the Technology of the X-band Accelerator Fabrication'', which is a part of the collaboration work of Accelerator Laboratory, ACC and Mechanical Engineering Center, MEC based on the joint X-band accelerator research of KEK and SLAC. The main topic of study in FY 2002 was the problem analysis, and seeking its counter-measures about pitting generated over the inner-surface of the accelerator cavities through high field tests. Therefore, to analyze and develop counter-measures for these pittings, manufacturing of several kinds of test accelerators and conducting analytical tests for the surface of cells have been mainly undertaken by ACC and MEC. On the other hand, basic studies of the cutting and bonding processes have shown effective results for the future production process through corroboration work with academic and industrial fields. Related scientists and engineers from various fields participated in this workshop and presented their works. As a keynote speech, Prof. Hitoshi Yamamoto, belonging to Tohoku University, presented ''The physics on linear collider'', and Assistant Prof. Nobukazu Toge, belonging to ACC of KEK, presented ''The Linear Collider Accelerator''. Also, as an invitation speech, former Prof. Nobuteru Hitomi, former Head of MEC, who was the originator of this workshop, and one of the leaders in X-band accelerator fabrication, presented ''The promotion and survey of fabrication technology on X-band accelerator''. These speeches were very instructive, and presented a chance to think about the direction of R and D in our project. Twenty-four papers, ten from KEK, including the keynote speech, seven from universities and seven from industrial companies, were presented and discussed ardently. Among the discussion, there was an opinion that a fast pace to establish mass-production technology is a major requirement for the

  20. All-optical control of group velocity dispersion in tellurite photonic crystal fibers.

    Science.gov (United States)

    Liu, Lai; Tian, Qijun; Liao, Meisong; Zhao, Dan; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

    2012-12-15

    We demonstrate all-optical control of group velocity dispersion (GVD) via optical Kerr effect in highly nonlinear tellurite photonic crystal fibers. The redshift of the zero-dispersion wavelength is over 307 nm, measured by soliton self-frequency shift cancellation, when the pump peak power of a 1.56 μm femtosecond fiber laser is increased to 11.6 kW. The all-optical control of GVD not only offers a new platform for constructing all-optical-control photonic devices but also promises a new class of experiments in nonlinear fiber optics and light-matter interactions.

  1. JEM-X: The X-ray monitor on INTEGRAL

    DEFF Research Database (Denmark)

    Budtz-Jørgensen, Carl; Lund, Niels; Westergaard, Niels Jørgen Stenfeldt

    2004-01-01

    The INTEGRAL X-ray monitor, JEM-X, (together with the two gamma ray instruments, SPI and IBIS) provides simultaneous imaging with arcminute angular resolution in the 3-35 keV band. The good angular resolution and low energy response of JEM-X plays an important role in the detection and identifica......The INTEGRAL X-ray monitor, JEM-X, (together with the two gamma ray instruments, SPI and IBIS) provides simultaneous imaging with arcminute angular resolution in the 3-35 keV band. The good angular resolution and low energy response of JEM-X plays an important role in the detection...

  2. X-ray Photoelectron Spectroscopic and Raman microscopic investigation of the variscite group minerals: Variscite, strengite, scorodite and mansfieldite

    Science.gov (United States)

    Kloprogge, J. Theo; Wood, Barry J.

    2017-10-01

    Several structurally related AsO4 and PO4 minerals, were studied with Raman microscopy and X-ray Photoelectron Spectroscopy (XPS). XPS revealed only Fe, As and O for scorodite. The Fe 2p, As 3d, and O 1s indicated one position for Fe2 +, while 2 different environments for O and As were observed. The O 1s at 530.3 eV and the As 3d 5/2 at 43.7 eV belonged to AsO4, while minor bands for O 1s at 531.3 eV and As 3d 5/2 at 44.8 eV were due to AsO4 groups exposed on the surface possibly forming OH-groups. Mansfieldite showed, besides Al, As and O, a trace of Co. The PO4 equivalent of mansfieldite is variscite. The change in crystal structure replacing As with P resulted in an increase in the binding energy (BE) of the Al 2p by 2.9 eV. The substitution of Fe3 + for Al3 + in the structure of strengite resulted in a Fe 2p at 710.8 eV. An increase in the Fe 2p BE of 4.8 eV was found between mansfieldite and strengite. The scorodite Raman OH-stretching region showed a sharp band at 3513 cm- 1 and a broad band around 3082 cm- 1. The spectrum of mansfieldite was like that of scorodite with a sharp band at 3536 cm- 1 and broader maxima at 3100 cm- 1 and 2888 cm- 1. Substituting Al in the arsenate structure instead of Fe resulted in a shift of the metal-OH-stretching mode by 23 cm- 1 towards higher wavenumbers due to a slightly longer H-bonding in mansfieldite compared to scorodite. The intense band for scorodite at 805 cm- 1 was ascribed to the symmetric stretching mode of the AsO4. The medium intensity bands at 890, 869, and 830 cm- 1 were ascribed to the internal modes. A significant shift towards higher wavenumbers was observed for mansfieldite. The strengite Raman spectrum in the 900-1150 cm- 1 shows a strong band at 981 cm- 1 accompanied by a series of less intense bands. The 981 cm- 1 band was assigned to the PO4 symmetric stretching mode, while the weak band at 1116 cm- 1 was the corresponding antisymmetric stretching mode. The remaining bands at 1009, 1023 and 1035 cm- 1

  3. On protecting the planet against cosmic attack: Ultrafast real-time estimate of the asteroid's radial velocity

    Science.gov (United States)

    Zakharchenko, V. D.; Kovalenko, I. G.

    2014-05-01

    A new method for the line-of-sight velocity estimation of a high-speed near-Earth object (asteroid, meteorite) is suggested. The method is based on the use of fractional, one-half order derivative of a Doppler signal. The algorithm suggested is much simpler and more economical than the classical one, and it appears preferable for use in orbital weapon systems of threat response. Application of fractional differentiation to quick evaluation of mean frequency location of the reflected Doppler signal is justified. The method allows an assessment of the mean frequency in the time domain without spectral analysis. An algorithm structure for the real-time estimation is presented. The velocity resolution estimates are made for typical asteroids in the X-band. It is shown that the wait time can be shortened by orders of magnitude compared with similar value in the case of a standard spectral processing.

  4. LoCuSS: The infall of X-ray groups onto massive clusters

    Science.gov (United States)

    Haines, C. P.; Finoguenov, A.; Smith, G. P.; Babul, A.; Egami, E.; Mazzotta, P.; Okabe, N.; Pereira, M. J.; Bianconi, M.; McGee, S. L.; Ziparo, F.; Campusano, L. E.; Loyola, C.

    2018-03-01

    Galaxy clusters are expected to form hierarchically in a ΛCDM universe, growing primarily through mergers with lower mass clusters and the continual accretion of group-mass halos. Galaxy clusters assemble late, doubling their masses since z ˜ 0.5, and so the outer regions of clusters should be replete with accreting group-mass systems. We present an XMM-Newton survey to search for X-ray groups in the infall regions of 23 massive galaxy clusters ( ˜ 1015 M⊙) at z ˜ 0.2, identifying 39 X-ray groups that have been spectroscopically confirmed to lie at the cluster redshift. These groups have mass estimates in the range 2 × 1013 - 7 × 1014 M⊙, and group-to-cluster mass ratios as low as 0.02. The comoving number density of X-ray groups in the infall regions is ˜25 × higher than that seen for isolated X-ray groups from the XXL survey. The average mass per cluster contained within these X-ray groups is 2.2 × 1014 M⊙, or 19 ± 5% of the mass within the primary cluster itself. We estimate that ˜1015 M⊙ clusters increase their masses by 16 ± 4% between z = 0.223 and the present day due to the accretion of groups with M200 ≥ 1013.2 M⊙. This represents about half of the expected mass growth rate of clusters at these late epochs. The other half is likely to come from smooth accretion of matter not bound within halos. The mass function of the infalling X-ray groups appears significantly top heavy with respect to that of "field" X-ray systems, consistent with expectations from numerical simulations, and the basic consequences of collapsed massive dark matter halos being biased tracers of the underlying large-scale density distribution.

  5. Band alignment study of lattice-matched In{sub 0.49}Ga{sub 0.51}P and Ge using x-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Owen, Man Hon Samuel, E-mail: m.owen.sg@ieee.org, E-mail: yeo@ieee.org; Zhou, Qian; Gong, Xiao; Yeo, Yee-Chia, E-mail: m.owen.sg@ieee.org, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 119260 (Singapore); Zhang, Zheng; Pan, Ji Sheng [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Loke, Wan Khai; Wicaksono, Satrio; Yoon, Soon Fatt [School of Electrical and Electronic Engineering, Nanyang Technological University (NTU), Nanyang Avenue, Singapore 639798 (Singapore); Tok, Eng Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

    2014-09-08

    Lattice-matched In{sub 0.49}Ga{sub 0.51}P was grown on a p-type Ge(100) substrate with a 10° off-cut towards the (111) by low temperature molecular beam epitaxy, and the band-alignment of In{sub 0.49}Ga{sub 0.51}P on Ge substrate was obtained by high resolution x-ray photoelectron spectroscopy. The valence band offset for the InGaP/Ge(100) interface was found to be 0.64 ± 0.12 eV, with a corresponding conduction band offset of 0.60 ± 0.12 eV. The InGaP/Ge interface is found to be of the type I band alignment.

  6. Variable Energy 2-MeV S-Band Linac for X-ray and Other Applications

    International Nuclear Information System (INIS)

    Howard Bender; Dave Schwellenbach; Ron Sturges; Rusty Trainham

    2008-01-01

    We will describe the design and operation of a compact, 2-MeV, S-band linear accelerator (linac) with variable energy tuning and short-pulse operation down to 15 ps with 100-A peak current. The design consists of a buncher cavity for short-pulse operation and two coupled resonator sections for acceleration. Single-pulse operation is accomplished through a fast injector system with a 219-MHz subharmonic buncher. The machine is intended to support a variety of applications, such as X-ray and electron beam diagnostic development and, recently, electron diffraction studies of phase transitions in shocked materials

  7. Variable Energy 2-MeV S-Band Linac for X-ray and Other Applications

    International Nuclear Information System (INIS)

    H. Bender; D. Schwellenbach; R. Sturges; R. Trainham

    2008-01-01

    This paper describes the design and operation of a compact, 2-MeV, S-band linear accelerator (linac) with variable energy tuning and short-pulse operation down to 15 ps with 100-A peak current. The design consists of a buncher cavity for short-pulse operation and two coupled resonator sections for acceleration. Single-pulse operation is accomplished through a fast injector system with a 219-MHz subharmonic buncher. The machine is intended to support a variety of applications, such as x-ray and electron beam diagnostic development, and recently, electron diffraction studies of phase transitions in shocked materials

  8. Laboratory Calibration of X-ray Velocimeters for Radiation Driven Winds and Outflows Surrounding X-ray Binaries and Active Galactic Nuclei

    Science.gov (United States)

    Brown, Gregory V.; Beiersdorfer, P.; Graf, A.; Hell, N.; Liedahl, D.; Magee, E. W.; Träbert, E.; Beilmann, C.; Bernitt, S.; Crespo-Lopez-Urritiua, J.; Eberle, S.; Kubicek, K.; Mäckel, V.; Rudolph, J.; Steinbrügge, R.; Ullrich, J.; Kelley, R. L.; Kilbourne, C. A.; Leutenegger, M.; Porter, F. S.; Rasmussen, A.; Simon, M.; Epp, S.

    2011-09-01

    High resolution measurements of X-ray absorption and fluorescence by radiation driven winds and outflows surrounding X-ray binaries and AGN provide a powerful means for measuring wind velocities. The accuracy of these X-ray velocimeters is limited by the accuracy of atomic data. For example, in the case of the high mass X-ray binary Vela X-1 the uncertainty in the calculated transition wavelengths of the K alpha lines produced by photoionization and photoexcitation of Si L-shell ions is comparable to the likely Doppler shifts, making it impossible to determine a reliable velocity. Similar problems also exist in the case of absorption of X-rays by M-shell Fe ions, which produces in some AGN the so-called unresolved transition array across the 15-17 angstrom band. In this case, there is a 15-45 milliangstrom variation among different wavelength calculations. The uncertainty in the calculations makes it impossible to reliably determine the true velocity structure of the outflow, and in turn, prevents a reliable determination of the mass-loss rate of the AGN. We present results of a recent series of laboratory experiments conducted using an electron beam ion trap coupled with the LCLS X-ray free electron laser and the BESSY-II synchrotron and designed to calibrate the velocimeters provided by high resolution instruments on Chandra and XMM-Newton. We also present results of resonant photoexcitation measurements of the transition wavelength of an Fe XVI satellite line 'coincident' with the 2p-3d Fe XVII line 3D at 15.26 angstroms. This line has never been resolved using emission spectroscopy and its measurement confirms the intensity of line 3D is sensitive to the relative abundance of Fe XVI and XVII and thus temperature. Work at LLNL was performed under the auspices of DOE under contract DE-AC53-07NA27344 and supported by NASA's APRA program.

  9. Microwave processed bulk and nano NiMg ferrites: A comparative study on X-band electromagnetic interference shielding properties

    Energy Technology Data Exchange (ETDEWEB)

    Chandra Babu Naidu, K., E-mail: chandrababu954@gmail.com [Ceramic Composite Laboratory, Centre for Crystal Growth, SAS, VIT University, Vellore 632014, Tamilnadu (India); Madhuri, W., E-mail: madhuriw12@gmail.com [Ceramic Composite Laboratory, Centre for Crystal Growth, SAS, VIT University, Vellore 632014, Tamilnadu (India); IFW, Leibniz Institute for Solid State and Materials Research, Technische Universität Dresden, 01069 Dresden (Germany)

    2017-02-01

    Bulk and nano Ni{sub 1-x}Mg{sub x}Fe{sub 2}O{sub 4} (x = 0–1) samples were synthesized via microwave double sintering and microwave assisted hydrothermal techniques respectively. The diffraction pattern confirmed the formation of cubic spinel phases in case of both the ferrites. The larger bulk densities were achieved to the bulk than that of nano. In addition, a comparative study on X-band (8.4–12 GHz) electromagnetic interference shielding properties of current bulk and nanomaterials was elucidated. The results showed that the bulk Ni{sub 0.6}Mg{sub 0.4}Fe{sub 2}O{sub 4} composition revealed the highest total shielding efficiency (SE{sub T}) of ∼17 dB. In comparison, the shielding efficiency values of all bulk contents were higher than that of nano because of larger bulk densities. Moreover, the ac-electromagnetic parameters such as electrical conductivity (σ{sub ac}), the respective real (ε′ & μ′) and imaginary parts (ε″ & μ″) of complex permittivity and permeability were investigated as a function of gigahertz frequency. The bulk ferrites of x = 0.4 & 0.6 showed the high ε″ of 10.26 & 6.71 and μ″ of 3.65 & 3.09 respectively at 12 GHz which can work as promising microwave absorber materials. Interestingly, nanoferrites exhibited negative μ″ values at few frequencies due to geometrical effects which improves the microwave absorption. - Highlights: • Bulk and nano NiMg ferrites are prepared by microwave and hydrothermal method. • X-band EMI shielding properties are studied for both bulk and nano ferrites. • Bulk Ni{sub 0.6}Mg{sub 0.4}Fe{sub 2}O{sub 4} revealed the highest SE{sub T} of ∼17 dB at 8.4 GHz. • Bulk x = 0.4 & 0.6 showed the high ε″ and μ″ at 12 GHz for absorber applications.

  10. A coupler for parasitic mode diagnosis in an X-band triaxial klystron amplifier

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2017-10-01

    Full Text Available The traditional methods of parasitic mode excitation diagnosis in an X-band triaxial klystron amplifier (TKA meet two difficulties: limited installation space and vacuum sealing. In order to solve these issues, a simple and compact coupler with good sealing performance, which can prevent air flow between the main and the auxiliary waveguides, is proposed and investigated experimentally. The coupler is designed with the aperture diffraction theory and the finite-different time-domain (FDTD method. The designed coupler consists of a main coaxial waveguide (for microwave transmission and a rectangular auxiliary waveguide (for parasitic mode diagnosis. The entire coupler structure has been fabricated by macromolecule polymer which is transparent to microwave signal in frequency range of X-band. The metal coating of about 200 microns has been performed through electroplating technique to ensure that the device operates well at high power. A small aperture is made in the metal coating. Hence, microwave can couple through the hole and the wave-transparent medium, whereas air flow is blocked by the wave-transparent medium. The coupling coefficient is analyzed and simulated with CST software. The coupler model is also included in particle-in-cell (PIC simulation with CHIPIC software and the associated parasitic mode excitation is studied. A frequency component of 11.46 GHz is observed in the FFT of the electric field of the drift tube and its corresponding competition mode appears as TE61 mode according to the electric field distribution. Besides, a frequency component of 10.8 GHz is also observed in the FFT of the electric field. After optimization of TE61 mode suppression, an experiment of the TKA with the designed coupler is carried out and the parasitic mode excitation at 10.8 GHz is observed through the designed coupler.

  11. Near-infrared metallicities, radial velocities, and spectral types for 447 nearby M dwarfs

    Energy Technology Data Exchange (ETDEWEB)

    Newton, Elisabeth R.; Charbonneau, David; Irwin, Jonathan; Berta-Thompson, Zachory K. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Rojas-Ayala, Barbara [Centro de Astrofsica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Covey, Kevin [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Lloyd, James P., E-mail: enewton@cfa.harvard.edu [Department of Astronomy, Cornell University, 226 Space Sciences Building, Ithaca, NY 14853 (United States)

    2014-01-01

    We present metallicities, radial velocities, and near-infrared (NIR) spectral types for 447 M dwarfs determined from moderate resolution (R ≈ 2000) NIR spectra obtained with the NASA Infrared Telescope Facility (IRTF)/SpeX. These M dwarfs are primarily targets of the MEarth Survey, a transiting planet survey searching for super Earths around mid-to-late M dwarfs within 33 pc. We present NIR spectral types for each star and new spectral templates for the IRTF in the Y, J, H, and K-bands, created using M dwarfs with near-solar metallicities. We developed two spectroscopic distance calibrations that use NIR spectral type or an index based on the curvature of the K-band continuum. Our distance calibration has a scatter of 14%. We searched 27 NIR spectral lines and 10 spectral indices for metallicity sensitive features, taking into account correlated noise in our estimates of the errors on these parameters. We calibrated our relation using 36 M dwarfs in common proper pairs with an F-, G-, or K-type star of known metallicity. We validated the physical association of these pairs using proper motions, radial velocities, and spectroscopic distance estimates. Our resulting metallicity calibration uses the sodium doublet at 2.2 μm as the sole indicator for metallicity. It has an accuracy of 0.12 dex inferred from the scatter between the metallicities of the primaries and the estimated metallicities of the secondaries. Our relation is valid for NIR spectral types from M1V to M5V and for –1.0 dex < [Fe/H] < +0.35 dex. We present a new color-color metallicity relation using J – H and J – K colors that directly relates two observables: the distance from the M dwarf main sequence and equivalent width of the sodium line at 2.2 μm. We used radial velocities of M dwarf binaries, observations at different epochs, and comparison between our measurements and precisely measured radial velocities to demonstrate a 4 km s{sup –1} accuracy.

  12. Kinematic classification of iliotibial band syndrome in runners.

    Science.gov (United States)

    Grau, S; Krauss, I; Maiwald, C; Axmann, D; Horstmann, T; Best, R

    2011-04-01

    Several inconsistent causative biomechanical factors are considered to be crucial in the occurrence of iliotibial band syndrome (ITBS). The focus of this study was on assessing differences in the kinematic characteristics between healthy runners [control group (CO)] and runners with ITBS in order to recommend treatment strategies to deal with this injury. Three-dimensional kinematics of barefoot running was used in the biomechanical setup. Both groups were matched with respect to gender, height and weight. After determining drop outs, the final population comprised 36 subjects (26 male and 10 female): 18 CO and 18 ITBS (13 male and five female, each). Kinematic evaluations indicate less hip adduction and frontal range of motion at the hip joint in runners with ITBS. Furthermore, maximum hip flexion velocity and maximum knee flexion velocity were lower in runners with ITBS. Lack of joint coordination, expressed as earlier hip flexion and a tendency toward earlier knee flexion, was found to be another discriminating variable in subjects with ITBS compared with CO subjects. We assume that an increase in range of motion at the hip joint, stretching of the hip abductors, as well as stretching the hamstrings, calf muscles and hip flexors will help treat ITBS. © 2009 John Wiley & Sons A/S.

  13. Emission bands of phosphorus and calculation of band structure of rare earth phosphides

    International Nuclear Information System (INIS)

    Al'perovich, G.I.; Gusatinskij, A.N.; Geguzin, I.I.; Blokhin, M.A.; Torbov, V.I.; Chukalin, V.I.; AN SSSR, Moscow. Inst. Novykh Khimicheskikh Problem)

    1977-01-01

    The method of x-ray emission spectroscopy has been used to investigate the electronic structure of monophosphides of rare-earth metals (REM). The fluorescence K bands of phosphorus have been obtained in LaP, PrP, SmP, GdP, TbP, DyP, HoP, ErP, TmP, YbP, and LuP and also the Lsub(2,3) bands of phosphorus in ErP, TmP, YbP, and LuP. Using the Green function technique involving the muffin-tin potential, the energy spectrum for ErP has been calculated in the single-electron approximation. The hystogram of electronic state distribution N(E) is compared with the experimental K and Lsub(2,3) bands of phosphorus in ErP. The agreement between the main details of N(E) and that of x-ray spectra allows to state that the model used provides a good description of the electron density distribution in crystals of REM monophosphides. In accordance with the character of the N(E) distribution the compounds under study are classified as semimetals or semiconductors with a very narrow forbidden band

  14. Impurity band effects on transport and thermoelectric properties of Fe2 -xNixVAl

    Science.gov (United States)

    Knapp, I.; Budinska, B.; Milosavljevic, D.; Heinrich, P.; Khmelevskyi, S.; Moser, R.; Podloucky, R.; Prenninger, P.; Bauer, E.

    2017-07-01

    Full Heusler alloys of the series Fe2 -xNixVAl ,0 ≤x ≤0.2 , were prepared and characterized, and their physical properties, relevant to the thermoelectric performance of such materials, were studied in a wide temperature range. The starting material Fe2VAl is characterized by a pseudogap of the electronic density of states near the Fermi energy, with a gap width of the order of 1 eV. Density functional theory calculations were performed by application of two approaches. In the framework of the local-spin-density approximation and coherent potential approximation, the electronic densities of states of substitutional alloys were calculated, revealing that with increasing Ni content the Fermi energy moves toward the conduction band, and consequently, the nature of electronic transport changes from p type to n type. It appears that Ni, due to its extra electrons, provides a narrow impurity band near the Fermi level. These states can be made responsible for the experimentally observed evolution of transport properties. Furthermore, the Vienna ab initio Simulation package (vasp) was utilized for deriving electronic, structural, and vibrational properties of ordered Fe2VAl and Fe1.75Ni0.25VAl . In particular, it is found that due to Ni substitution there is a general shift to lower phonon frequencies by about 2 THz as compared to the undoped case. Associated to these modifications, the electrical resistivity, ρ (T ) , changes from a semiconducting-like behavior to a nonsimple metallic behavior, while the Seebeck coefficient reaches values of the order of -80 μ V /K around room temperature for the sample x =0.2 . The increase of the Ni content, in addition, goes along with a substantial reduction of the lattice part of the thermal conductivity. This change is analyzed in detail in terms of a disorder parameter Γ , characterizing the derangement of the crystalline lattice due to the substitution of Fe by Ni. Ab initio calculations of the phonon dynamics carried out

  15. Numerical investigation of transient beam loading compensation in JLC X-band main linac

    International Nuclear Information System (INIS)

    Syrachev, I.V.; Higo, T.

    1996-06-01

    In the present paper, two methods, 'staggered timing' and 'RF modulation', were studied for the transient beam loading compensation in the JLC X-band main linac. The inter bunch energy spread was found to be easily reduced down to less than ±0.06% with 10 sets of injection timings along the linac in the former case while with a simple linear ramping of the input RF voltage in the latter case. For both cases the energy transfer efficiencies from the power source to the beam were exactly the same. The tolerance of the beam intensity jitter was found to be ±1% for the multibunch energy spread of ±0.1%. (author)

  16. STATUS OF X-BAND STANDING WAVE STRUCTURE STUDIES AT SLAC

    International Nuclear Information System (INIS)

    Dolgashev, Valery A.

    2003-01-01

    The linacs proposed for the Next Linear Collider (NLC) and Japanese Linear Collider (JLC) would contain several thousand X-Band accelerator structures that would operate at a loaded gradient of 50 MV/m. An extensive experimental and theoretical program is underway at SLAC, FNAL and KEK to develop structures that reliably operate at this gradient. The development of standing wave structures is a part of this program. The properties of standing wave structures allow them to operate at the loaded gradient in contrast to traveling wave structures that need conditioning to the unloaded gradient (65 MV/m for NLC/JLC). The gradients in the standing structures tested thus far have been limited by input coupler breakdowns. The behavior of these breakdowns is consistent with a model of pulsed heating due to high magnetic fields. New input couplers have been designed to reduce maximum magnetic fields. This paper discusses design considerations related to high power performance, wakefield suppression and results of high power tests of prototype standing wave structures

  17. Band gap determination of thin praseodymium oxide layers on aluminium oxynitride films

    Energy Technology Data Exchange (ETDEWEB)

    Bergholz, Matthias; Schmeisser, Dieter [Brandenburgische Technische Universitaet, Cottbus (Germany). Angewandte Physik - Sensorik

    2008-07-01

    High-k dielectrics are important as never before in semiconductor industry. We investigate Pr{sub 2}O{sub 3} as one representative of this group on silicon and silicon-aluminium oxynitride substrates. In earlier work we observed the positive influence of this AlO{sub x}N{sub y} intermediate layer on the electrical properties of the Pr{sub 2}O{sub 3} layer. Now we present in-situ EELS, XPS and UPS measurements of gradually grown thin Pr{sub 2}O{sub 3} on AlO{sub x}N{sub y}. From these measurements we determine the band structure and find a very fast change of the band gap for the first few A, coupled with n-type behaviour for the Pr{sub 2}O{sub 3} film. These results are compared with RIXS measurements of a 5 nm Pr{sub 2}O{sub 3} on a 1 nm thick AlO{sub x}N{sub y} layer.

  18. New developed cylindrical TM010 mode EPR cavity for X-band in vivo tooth dosimetry.

    Directory of Open Access Journals (Sweden)

    Guo Junwang

    Full Text Available EPR tooth in vivo dosimetry is an attractive approach for initial triage after unexpected nuclear events. An X-band cylindrical TM010 mode resonant cavity was developed for in vivo tooth dosimetry and used in EPR applications for the first time. The cavity had a trapezoidal measuring aperture at the exact position of the cavity's cylindrical wall where strong microwave magnetic field H1 concentrated and weak microwave electric field E1 distributed. Theoretical calculations and simulations were used to design and optimize the cavity parameters. The cavity features were evaluated by measuring DPPH sample, intact incisor samples embed in a gum model and the rhesus monkey teeth. The results showed that the cavity worked at designed frequency and had the ability to make EPR spectroscopy in relative high sensitivity. Sufficient modulation amplitude and microwave power could be applied into the aperture. Radiation induced EPR signal could be observed remarkably from 1 Gy irradiated intact incisor within only 30 seconds, which was among the best in scan time and detection limit. The in vivo spectroscopy was also realized by acquiring the radiation induced EPR signal from teeth of rhesus monkey whose teeth was irradiated by dose of 2 Gy. The results suggested that the cavity was sensitive to meet the demand to assess doses of significant level in short time. This cavity provided a very potential option for the development of X-band in vivo dosimetry.

  19. Bandgap engineering of the Lu{sub x}Y{sub 1−x}PO{sub 4} mixed crystals

    Energy Technology Data Exchange (ETDEWEB)

    Levushkina, V.S., E-mail: viktoriia.levushkina@ut.ee [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Physics Faculty, Moscow State University, Leninskiye Gory 1-2, 11991 Moscow (Russian Federation); Spassky, D.A. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Skobeltsyn Institute of Nuclear Physics, Moscow State University, Leninskiye Gory 1-2, 11991 Moscow (Russian Federation); Aleksanyan, E.M. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); A. Alikhanyan National Science Laboratory, Yerevan Physics Institute, Alikhanyan Yeghbayrneri St. 2, 0036 Yerevan (Armenia); Brik, M.G. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); College of Sciences, Chongqing University of Posts and Telecommunications, 400065 Chongqing (China); Institute of Physics, Jan Dlugosz University, Armii Krajowej 13/15, PL-42200 Czestochowa (Poland); Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Tretyakova, M.S.; Zadneprovski, B.I. [Central Research and Development Institute of Chemistry and Mechanics, Nagatinskaya St. 16a, 115487 Moscow (Russian Federation); Belsky, A.N. [Institute of Light and Matter, CNRS, University Lyon1, 69622 Villeurbanne (France)

    2016-03-15

    Bandgap modification of the Lu{sub x}Y{sub 1−x}PO{sub 4} mixed crystals has been studied by thermostimulated luminescence (TSL) and ab-initio calculation methods. Doping of Lu{sub x}Y{sub 1−x}PO{sub 4} with Ce{sup 3+} allowed to follow up the changes of electron traps depth, caused by the modification of the bottom of conduction band. The observed gradual shift of the most intensive TSL peaks to higher temperatures with increase of x value was connected with the high-energy shift of the conduction band bottom. According to the band structure calculations the bottom of the conduction band is formed by the 5d and 4d states of Lu and Y, respectively. Therefore, substitution of one cation by another is responsible for the observed variation of the electronic and optical properties. Doping with Eu{sup 3+} was used to study the modification of the hole traps and the top of the valence band in Lu{sub x}Y{sub 1−x}PO{sub 4}. The independence of the TSL peaks position on x value in Lu{sub x}Y{sub 1−x}PO{sub 4}:Eu{sup 3+} allows to conclude that the top of the valence band is negligibly affected by the cation substitution. According to the band structure calculations the top of the valence band is formed by the O 2p electronic states, which are not affected by the cation substitution. The resulting increase of the bandgap with x value is confirmed by the data of ab-initio calculations. - Highlights: • Band structure modification with x in Lu{sub x}Y{sub 1−x}PO{sub 4}:RE{sup 3+} (RE=Ce, Eu) is studied. • Depth of electron traps is affected by the bandgap modification. • Increase of bandgap with x is due to the shift of conduction band bottom.

  20. Slope Superficial Displacement Monitoring by Small Baseline SAR Interferometry Using Data from L-band ALOS PALSAR and X-band TerraSAR: A Case Study of Hong Kong, China

    Directory of Open Access Journals (Sweden)

    Fulong Chen

    2014-02-01

    Full Text Available Owing to the development of spaceborne synthetic aperture radar (SAR platforms, and in particular the increase in the availability of multi-source (multi-band and multi-resolution data, it is now feasible to design a surface displacement monitoring application using multi-temporal SAR interferometry (MT-InSAR. Landslides have high socio-economic impacts in many countries because of potential geo-hazards and heavy casualties. In this study, taking into account the merits of ALOS PALSAR (L-band, good coherence preservation and TerraSAR (X-band, high resolution and short revisit times data, we applied an improved small baseline InSAR (SB-InSAR with 3-D phase unwrapping approach, to monitor slope superficial displacement in Hong Kong, China, a mountainous subtropical zone city influenced by over-urbanization and heavy monsoonal rains. Results revealed that the synergistic use of PALSAR and TerraSAR data produces different outcomes in relation to data reliability and spatial-temporal resolution, and hence could be of significant value for a comprehensive understanding and monitoring of unstable slopes.

  1. Numerical calculation of acoustic radiation from band-vibrating structures via FEM/FAQP method

    Directory of Open Access Journals (Sweden)

    GAO Honglin

    2017-08-01

    Full Text Available The Finite Element Method (FEM combined with the Frequency Averaged Quadratic Pressure method (FAQP are used to calculate the acoustic radiation of structures excited in the frequency band. The surface particle velocity of stiffened cylindrical shells under frequency band excitation is calculated using finite element software, the normal vibration velocity is converted from the surface particle velocity to calculate the average energy source (frequency averaged across intensity, frequency averaged across pressure and frequency averaged across velocity, and the FAQP method is used to calculate the average sound pressure level within the bandwidth. The average sound pressure levels are then compared with the bandwidth using finite element and boundary element software, and the results show that FEM combined with FAQP is more suitable for high frequencies and can be used to calculate the average sound pressure level in the 1/3 octave band with good stability, presenting an alternative to applying frequency-by-frequency calculation and the average frequency process. The FEM/FAQP method can be used as a prediction method for calculating acoustic radiation while taking the randomness of vibration at medium and high frequencies into consideration.

  2. Clustering of germanium atoms in silica glass responsible for the 3.1 eV emission band studied by optical absorption and X-ray absorption fine structure analysis

    International Nuclear Information System (INIS)

    Yoshida, Tomoko; Muto, Shunsuke; Yuliati, Leny; Yoshida, Hisao; Inada, Yasuhiro

    2009-01-01

    Correlation between the 3.1 eV emission band and local atomic configuration was systematically examined for Ge + implanted silica glass by UV-vis optical absorption spectroscopy and X-ray absorption fine structure (XAFS) analysis. The 2.7 eV emission band, commonly observed in defective silica, was replaced by the sharp and intense 3.1 eV emission band for the Ge + fluence > 2 x 10 16 cm -2 , in which UV-vis absorption spectra suggested clustering of Ge atoms with the size ∼1 nm. XAFS spectroscopy indicated that the Ge atoms were under coordinated with oxygen atoms nearly at a neutral valence state on average. The present results are consistent with the previous ESR study but imply that the small Ge clusters rather than the O=Ge: complexes (point defects) are responsible for the 3.1 eV emission band.

  3. A simple solution-phase approach to synthesize high quality ternary AgInSe2 and band gap tunable quaternary AgIn(S1-xSe x)2 nanocrystals

    KAUST Repository

    Bai, Tianyu

    2014-01-01

    A facile solution-phase route for the preparation of AgInSe2 nanocrystals was developed by using silver nitrate, indium stearate, and oleylamine-selenium (OAm-Se) as precursors. The evolution process of the AgInSe2 nanocrystals is discussed in detail and different reaction conditions all have a great impact on the growth and morphology of the nanocrystals. Alloyed AgIn(S1-xSex)2 nanocrystals with controlled composition across the entire range (0 ≤ x ≤ 1) was also successfully prepared by modulating the S/Se reactant mole ratio. X-ray diffraction (XRD), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) were used to confirm that the alloyed AgIn(S1-xSex)2 nanocrystals are homogeneous. The UV-vis absorption spectra revealed that the band gap energies of the alloyed AgIn(S1-xSex)2 nanocrystals could be continuously tuned by increasing the Se content. © The Royal Society of Chemistry 2014.

  4. Optoelectronic Properties of X-Doped (X = O, S, Te) Photovoltaic CSe with Puckered Structure.

    Science.gov (United States)

    Zhang, Qiang; Xin, Tianyuan; Lu, Xiaoke; Wang, Yuexia

    2018-03-16

    We exploited novel two-dimensional (2D) carbon selenide (CSe) with a structure analogous to phosphorene, and probed its electronics and optoelectronics. Calculating phonon spectra using the density functional perturbation theory (DFPT) method indicated that 2D CSe possesses dynamic stability, which made it possible to tune and equip CSe with outstanding properties by way of X-doping (X = O, S, Te), i.e., X substituting Se atoms. Then systematic investigation on the structural, electronic, and optical properties of pristine and X-doped monolayer CSe was carried out using the density functional theory (DFT) method. It was found that the bonding feature of C-X is intimately associated with the electronegativity and radius of the doping atoms, which leads to diverse electronic and optical properties for doping different group VI elements. All the systems possess direct gaps, except for O-doping. Substituting O for Se atoms in monolayer CSe brings about a transition from a direct Γ-Γ band gap to an indirect Γ-Y band gap. Moreover, the value of the band gap decreases with increased doping concentration and radius of doping atoms. A red shift in absorption spectra occurs toward the visible range of radiation after doping, and the red-shift phenomenon becomes more obvious with increased radius and concentration of doping atoms. The results can be useful for filtering doping atoms according to their radius or electronegativity in order to tailor optical spectra efficiently.

  5. Optoelectronic Properties of X-Doped (X = O, S, Te Photovoltaic CSe with Puckered Structure

    Directory of Open Access Journals (Sweden)

    Qiang Zhang

    2018-03-01

    Full Text Available We exploited novel two-dimensional (2D carbon selenide (CSe with a structure analogous to phosphorene, and probed its electronics and optoelectronics. Calculating phonon spectra using the density functional perturbation theory (DFPT method indicated that 2D CSe possesses dynamic stability, which made it possible to tune and equip CSe with outstanding properties by way of X-doping (X = O, S, Te, i.e., X substituting Se atoms. Then systematic investigation on the structural, electronic, and optical properties of pristine and X-doped monolayer CSe was carried out using the density functional theory (DFT method. It was found that the bonding feature of C-X is intimately associated with the electronegativity and radius of the doping atoms, which leads to diverse electronic and optical properties for doping different group VI elements. All the systems possess direct gaps, except for O-doping. Substituting O for Se atoms in monolayer CSe brings about a transition from a direct Γ-Γ band gap to an indirect Γ-Y band gap. Moreover, the value of the band gap decreases with increased doping concentration and radius of doping atoms. A red shift in absorption spectra occurs toward the visible range of radiation after doping, and the red-shift phenomenon becomes more obvious with increased radius and concentration of doping atoms. The results can be useful for filtering doping atoms according to their radius or electronegativity in order to tailor optical spectra efficiently.

  6. Band alignment of atomic layer deposited MgO/Zn0.8Al0.2O heterointerface determined by charge corrected X-ray photoelectron spectroscopy

    Science.gov (United States)

    Yan, Baojun; Liu, Shulin; Yang, Yuzhen; Heng, Yuekun

    2016-05-01

    Pure magnesium (MgO) and zinc oxide doped with aluminum oxide (Zn0.8Al0.2O) were prepared via atomic layer deposition. We have studied the structure and band gap of bulk Zn0.8Al0.2O material by X-ray diffractometer (XRD) and Tauc method, and the band offsets and alignment of atomic layer deposited MgO/Zn0.8Al0.2O heterointerface were investigated systematically using X-ray photoelectron spectroscopy (XPS) in this study. Different methodologies, such as neutralizing electron gun, the use of C 1s peak recalibration and zero charging method, were applied to recover the actual position of the core levels in insulator materials which were easily influenced by differential charging phenomena. Schematic band alignment diagram, valence band offset (ΔEV) and conduction band offset (ΔEC) for the interface of the MgO/Zn0.8Al0.2O heterostructure have been constructed. An accurate value of ΔEV = 0.72 ± 0.11 eV was obtained from various combinations of core levels of heterojunction with varied MgO thickness. Given the experimental band gaps of 7.83 eV for MgO and 5.29 eV for Zn0.8Al0.2O, a type-II heterojunction with a ΔEC of 3.26 ± 0.11 eV was found. Band offsets and alignment studies of these heterojunctions are important for gaining deep consideration to the design of various optoelectronic devices based on such heterointerface.

  7. Design of a Miniaturized X-Band Diplexer Based on Novel One-Third-Mode Substrate Integrated Resonator Filters

    Science.gov (United States)

    Zhang, Hao; Kang, Wei; Wu, Wen

    2017-12-01

    In this paper, a miniaturized diplexer designed with two novel one-third-mode substrate integrated resonator (OTMSIR) filters has been presented. The one-third triangular resonator cavity with two transmission zeros (TZs) and two transmission poles is investigated. TZs are implemented by taking cross couplings of lower order modes in this design. The diplexer is then obtained by integrating two different sizes of OTMSIR filters with a common T-junction structure. A X-band diplexer operating at 10 GHz and 11.5 GHz is designed on a substrate with a dielectric constant of 3.55 to verify the above design concept. This novel structure features more compact size, better transmission performance, higher out of band rejection and easier integration compared with other circuits. A good agreement is obtained between the simulations and the measured results.

  8. Electronic structure of ZrX2 (X = Se, Te)

    Science.gov (United States)

    Shkvarin, A. S.; Merentsov, A. I.; Shkvarina, E. G.; Yarmoshenko, Yu. M.; Píš, I.; Nappini, S.; Titov, A. N.

    2018-03-01

    The electronic structure of the ZrX2 (X = Se, Te) compounds has been studied using photoelectron, resonant photoelectron and X-ray absorption spectroscopy, theoretical calculations of the X-ray absorption spectra, and density of electronic states. It was found that the absorption spectra and valence band spectra are influenced by the chalcogen type. The results of the multiplet calculation of the Zr4+ atom show that the change in the splitting in the crystal field, which is described by the 10Dq parameter, is due to the change in the ratio of covalent and ionic contributions to the chemical bond. The resonance band near the Fermi level in the valence band spectra is observed for ZrTe2 in the Zr 3p-4d resonant excitation mode. The extent of photon energy indicates the charge localization on the Zr atom. Similar resonance band for ZrSe2 is absent; it indicates the presence of a gap at the Fermi level.

  9. Towards from indirect to direct band gap and optical properties of XYP{sub 2} (X=Zn, Cd; Y=Si, Ge, Sn)

    Energy Technology Data Exchange (ETDEWEB)

    Ullah, Sibghat [Department of Physics, Hazara University Mansehra, KPK (Pakistan); Murtaza, G., E-mail: murtaza@icp.edu.pk [Materials Modeling Lab, Department of Physics, Islamia College, Peshawar (Pakistan); Khenata, R. [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 Mascara (Algeria); Reshak, A.H. [New Technologies—Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Hayat, S.S. [Department of Physics, Hazara University Mansehra, KPK (Pakistan); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)

    2014-05-15

    First principle calculations are performed to predict the electronic and optical properties of XYP{sub 2} (X=Zn, Cd; Y=Si, Ge, Sn) compounds. The calculations show an excellent agreement with the available experimental results as compared to previous calculations. The band gap value decreases by changing the cations X from Zn to Cd as well as Y from Si to Ge to Sn in XYP{sub 2}. The d-states of the Zn and Cd contribute majorly in the density of states. Bonding nature in these compounds is analyzed from the electron density plots. Optical response of these compounds is noted from the complex refractive index and reflectivity spectra. The wide direct band gap and the high reflectivity in the visible and ultraviolet regions for these compounds make them potential candidates for optoelectronic and photonic applications.

  10. Using velocity dispersion to estimate halo mass: Is the Local Group in tension with ΛCDM?

    Science.gov (United States)

    Elahi, Pascal J.; Power, Chris; Lagos, Claudia del P.; Poulton, Rhys; Robotham, Aaron S. G.

    2018-06-01

    Satellite galaxies are commonly used as tracers to measure the line-of-sight (LOS)velocity dispersion (σLOS) of the dark matter halo associated with their central galaxy, and thereby to estimate the halo's mass. Recent observational dispersion estimates of the Local Group, including the Milky Way and M31, suggest σ ˜50 km s-1, which is surprisingly low when compared to the theoretical expectation of σ ˜100 km s-1 for systems of their mass. Does this pose a problem for Lambda cold dark matter (ΛCDM)? We explore this tension using the SURFS suite of N-body simulations, containing over 10000 (sub)haloes with well tracked orbits. We test how well a central galaxy's host halo velocity dispersion can be recovered by sampling σLOS of subhaloes and surrounding haloes. Our results demonstrate that σLOS is biased mass proxy. We define an optimal window in vLOS and projected distance (Dp) - 0.5 ≲ Dp/Rvir ≲ 1.0 and vLOS ≲ 0.5Vesc, where Rvir is the virial radius and Vesc is the escape velocity - such that the scatter in LOS to halo dispersion is minimized - σLOS = (0.5 ± 0.1)σv, H. We argue that this window should be used to measure LOS dispersions as a proxy for mass, as it minimises scatter in the σLOS-Mvir relation. This bias also naturally explains the results from McConnachie (2012), who used similar cuts when estimating σLOS, LG, producing a bias of σLG = (0.44 ± 0.14)σv, H. We conclude that the Local Group's velocity dispersion does not pose a problem for ΛCDM and has a mass of log M_{LG, vir}/M_{⊙}=12.0^{+0.8}_{-2.0}.

  11. A compact broadband high efficient X-band 9-watt PHEMT MMIC high-power amplifier for phased array radar applications

    NARCIS (Netherlands)

    Hek, A.P. de; Hunneman, P.A.H.; Demmler, M.; Hulsmann, A.

    1999-01-01

    ln this paper the development and measurement results of a compact broadband 9-Watt high efficient X-band high-power amplifier are discussed. The described amplifier has the following state-of-the art performance: an average ouput power of 9 Watt, a gain of 20 dB and an average Power Added

  12. single crystal growth, x-ray structure analysis, optical band gap

    African Journals Online (AJOL)

    2015-09-01

    Sep 1, 2015 ... Hg...Hgand Cl...Cl interactions are stabilizing the structures in 3D pattern. UV-vis absorption spectra illustrate the change in opticalband gap from 3.01eVto 3.42eV on replacing the metal halide group.Raman and Hyper-Raman tensors calculations were performed based on single crystal X-ray data and the ...

  13. Parametric interactions in high-Tc superconducting step edge junctions at X-band. [Y-Ba-Cu-O

    Energy Technology Data Exchange (ETDEWEB)

    Kain, A.Z. (TRW Space and Tech. Group, Redondo Beach, CA (United States)); Fetterman, H.R. (Electrical Engineering Dept., Univ. of California at Los Angeles (United States))

    1993-04-20

    We have fabricated and tested both single junctions and series arrays of YBCO step edge junctions for four photon parametric effects at X band as a first step in developing a parametric amplifier at 60 GHz. The series array of 25 junctions at 10.3 Ghz shows a 10 dB increase in reflected signal power as the pump power is increased, while the single junction at 12.2 GHz indicates a 2 dB change. The reflected power at the characteristic idler frequency of 2[omega][sub p]-[omega][sub s] is evidence of true Josephson junction parametric interaction. We are currently investigating the use of thallium based films at 60 GHz which offer a broader range of operating temperatures than does YBCO. Our design for a parametric amplifier at V band is a combination of microstrip based series arrays of junctions and an antipodal finline transition. (orig.)

  14. General analysis of group velocity effects in collinear optical parametric amplifiers and generators.

    Science.gov (United States)

    Arisholm, Gunnar

    2007-05-14

    Group velocity mismatch (GVM) is a major concern in the design of optical parametric amplifiers (OPAs) and generators (OPGs) for pulses shorter than a few picoseconds. By simplifying the coupled propagation equations and exploiting their scaling properties, the number of free parameters for a collinear OPA is reduced to a level where the parameter space can be studied systematically by simulations. The resulting set of figures show the combinations of material parameters and pulse lengths for which high performance can be achieved, and they can serve as a basis for a design.

  15. Effects of spontaneously generated coherence on the group velocity in a V system

    International Nuclear Information System (INIS)

    Bai Yanfeng; Guo Hong; Han, Dingan; Sun Hui

    2005-01-01

    We show how the application of an incoherent pumping can produce a variety of effects on the propagation of a weak electromagnetic pulse in a V system with spontaneously generated coherence (SGC). There exists an incoherent pumping rate which makes the group velocity reach the extremum near the region of two-photon resonant excitation. The existence of SGC is just the cause for the occurrence of the extremum, and it may also be regarded as a knob which can be used to manipulate light propagation from subluminal to superluminal

  16. Band alignment of atomic layer deposited MgO/Zn{sub 0.8}Al{sub 0.2}O heterointerface determined by charge corrected X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Baojun, E-mail: yanbj@ihep.ac.cn [State Key Laboratory of Particle Detection and Electronics, Institute of High Energy Physics of Chinese Academy of Sciences, Beijing P. O. Box 100049 (China); Liu, Shulin [State Key Laboratory of Particle Detection and Electronics, Institute of High Energy Physics of Chinese Academy of Sciences, Beijing P. O. Box 100049 (China); Yang, Yuzhen [State Key Laboratory of Particle Detection and Electronics, Institute of High Energy Physics of Chinese Academy of Sciences, Beijing P. O. Box 100049 (China); Department of Physics, Nanjing University, Nanjing P. O. Box 210093 (China); Heng, Yuekun [State Key Laboratory of Particle Detection and Electronics, Institute of High Energy Physics of Chinese Academy of Sciences, Beijing P. O. Box 100049 (China)

    2016-05-15

    Highlights: • Band alignment of MgO/Zn{sub 0.8}Al{sub 0.2}O heterojunction were investigated systematically using charge corrected X-ray photoelectron spectroscopy. • Differential charging phenomenon is observed in determination VBOs of insulator/semiconductor heterojunction. • Valence and conduction band offsets have been determined to be 0.72 ± 0.11 eV and 3.26 ± 0.11 eV, respectively, with a type-II band line-up. - Abstract: Pure magnesium (MgO) and zinc oxide doped with aluminum oxide (Zn{sub 0.8}Al{sub 0.2}O) were prepared via atomic layer deposition. We have studied the structure and band gap of bulk Zn{sub 0.8}Al{sub 0.2}O material by X-ray diffractometer (XRD) and Tauc method, and the band offsets and alignment of atomic layer deposited MgO/Zn{sub 0.8}Al{sub 0.2}O heterointerface were investigated systematically using X-ray photoelectron spectroscopy (XPS) in this study. Different methodologies, such as neutralizing electron gun, the use of C 1s peak recalibration and zero charging method, were applied to recover the actual position of the core levels in insulator materials which were easily influenced by differential charging phenomena. Schematic band alignment diagram, valence band offset (ΔE{sub V}) and conduction band offset (ΔE{sub C}) for the interface of the MgO/Zn{sub 0.8}Al{sub 0.2}O heterostructure have been constructed. An accurate value of ΔE{sub V} = 0.72 ± 0.11 eV was obtained from various combinations of core levels of heterojunction with varied MgO thickness. Given the experimental band gaps of 7.83 eV for MgO and 5.29 eV for Zn{sub 0.8}Al{sub 0.2}O, a type-II heterojunction with a ΔE{sub C} of 3.26 ± 0.11 eV was found. Band offsets and alignment studies of these heterojunctions are important for gaining deep consideration to the design of various optoelectronic devices based on such heterointerface.

  17. Slip-band formation and dislocation kinetics in the stage I deformation of neutron-irradiated copper single crystals

    International Nuclear Information System (INIS)

    Kitajima, Sadakichi; Shinohara, Kazutoshi; Kutsuwada, Masanori

    1995-01-01

    The velocity of edge and screw dislocations moving in primary slip bands and the formation rate of primary slip bands were measured in stage I deformation of neutron-irradiated copper single crystals at different strain rates at room temperature using micro-cinematography and optical micrography. The average velocity of edge dislocations was larger at least by one order than that of screw ones, and that of screw dislocations did not depend so strongly on strain rate. The formation rate of primary slip bands was proportional to strain rate. From these results, it is concluded that (1) jogs produced on moving dislocations by cutting dislocation loops result in the difference in velocity between edge and screw dislocations and (2) the change in the density of mobile dislocations as well as velocity of dislocations is responsible for the change of plastic strain rate of a crystal. (author)

  18. X-band accelerator structures: On going R&D at the INFN

    Energy Technology Data Exchange (ETDEWEB)

    Gatti, G. [INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, Frascati, 00044 Roma (Italy); Marcelli, A. [INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, Frascati, 00044 Roma (Italy); RICMASS, Rome International Center for Materials Science Superstripes, Via dei Sabelli 119A, 00185 Rome (Italy); Spataro, B. [INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, Frascati, 00044 Roma (Italy); Dolgashev, V.; Lewandowski, J.; Tantawi, S.G.; Yeremian, A.D. [SLAC-National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Higashi, Y. [Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495 (Japan); Rosenzweig, J. [UCLA-Department of Physics and Astronomy, 405 Hilgard Ave., Los Angeles, CA 90095 (United States); Sarti, S. [University of Rome Sapienza, Dipartimento di Fisica, P.le A. Moro 5, 00185 Rome (Italy); Caliendo, C. [Istituto di Acustica e Sensoristica, Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Castorina, G. [INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, Frascati, 00044 Roma (Italy); University of Catania, Dipartimento di Ingegneria Elettrica, Elettronica e Informatica, 95126 Catania (Italy); Cibin, G. [Diamond Light Source, Chilton, Didcot, Oxon OX110DE (United Kingdom); Carfora, L. [INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, Frascati, 00044 Roma (Italy); Leonardi, O. [INFN, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Rigato, V. [INFN, Laboratori Nazionali di Legnaro, Legnaro, Padova (Italy); Campostrini, M. [INFN, Laboratori Nazionali di Legnaro, Legnaro, Padova (Italy); Department of Industrial Engineering, University of Trento, via Sommarive, 9, 38123 Trento (Italy)

    2016-09-01

    The next generation of accelerators, from the compact to the large infrastructure dedicated to high energy physics, is highly demanding in terms of accelerating gradients. To upgrade performances of X band linacs at 11.424 GHz many resources are devoted to achieve high accelerating gradients and at the same time to obtain a high reliability. In the framework of a three-year funded project by the Vth Committee of the INFN to the Laboratori Nazionali di Frascati (LNF) and to the Laboratori Nazionali di Legnaro (LNL). Within a broad international collaboration the LNF has been involved in the design, manufacture and test of compact high power standing wave (SW) sections operating at high frequency while LNL is actively involved in the development of new materials and multilayers using PVD (Physical Vapor Deposition) methods. We will report about the status of the accelerating device and of the different ongoing R&D activities and characterization procedures such as tests of different materials and metallic coatings.

  19. HIGH POWER TESTS OF A MULTIMODE X-BAND RF DISTRIBUTION SYSTEMS

    International Nuclear Information System (INIS)

    Tantawi, S

    2004-01-01

    We present a multimode X-band rf pulse compression system suitable for the Next Linear Collider (NLC). The NLC main linacs operate at 11.424 GHz. A single NLC rf unit is required which produce 400 ns pulses with 600 MW of peak power. Each rf unit should power approximately 5 meters of accelerator structures. These rf units consist of two 75 MW klystrons and a dual-moded resonant delay line pulse compression system [1] that produce a flat output pulse. The pulse compression system components are all over moded and most components are design to operate with two modes at the same time. This approach allows increasing the power handling capabilities of the system while maintain a compact inexpensive system. We detail the design of this system and present experimental cold test results. The high power testing of the system is verified using four 50-MW solenoid focused klystrons. These Klystrons should be able to push the system beyond NLC requirements

  20. Multifractal analysis of different hydrological products of X-band radar

    Science.gov (United States)

    Skouri-Plakali, Ilektra; Da Silva Rocha Paz, Igor; Ichiba, Abdellah; Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel

    2017-04-01

    Rainfall is widely considered as the hydrological process that triggers all the others. Its accurate measurements are crucial especially when they are used afterwards for the hydrological modeling of urban and peri-urban catchments for decision-making. Rainfall is a complex process and is scale dependent in space and time. Hence a high spatial and temporal resolution of the data is more appropriate for urban modeling. Therefore, a great interest of high-resolution measurements of precipitation in space and time is manifested. Radar technologies have not stopped evolving since their first appearance about the mid-twentieth. Indeed, the turning point work by Marshall-Palmer (1948) has established the Z - R power-law relation that has been widely used, with major scientific efforts being devoted to find "the best choice" of the two associated parameters. Nowadays X-band radars, being provided with dual-polarization and Doppler means, offer more accurate data of higher resolution. The fact that drops are oblate induces a differential phase shift between the two polarizations. The quantity most commonly used for the rainfall rate computation is actually the specific differential phase shift, which is the gradient of the differential phase shift along the radial beam direction. It is even stronger correlated to the rain rate R than reflectivity Z. Hence the rain rate can be computed with a different power-law relation, which again depends on only two parameters. Furthermore, an attenuation correction is needed to adjust the loss of radar energy due to the absorption and scattering as it passes through the atmosphere. Due to natural variations of reflectivity with altitude, vertical profile of reflectivity should be corrected as well. There are some other typical radar data filtering procedures, all resulting in various hydrological products. In this work, we use the Universal Multifractal framework to analyze and to inter-compare different products of X-band radar

  1. Simultaneous microwave photonic and phononic band gaps in piezoelectric–piezomagnetic superlattices with three types of domains in a unit cell

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Zheng-hua [Xiangnan University-Gospell Joint Laboratory of Microwave Communication Technology, Xiangnan University, Chenzhou 423000 (China); Jiang, Zheng-Sheng [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Chen, Tao [Laboratory of Quantum Information and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Lei, Da-Jun [Xiangnan University-Gospell Joint Laboratory of Microwave Communication Technology, Xiangnan University, Chenzhou 423000 (China); Yan, Wen-Yan, E-mail: yanwenyan88@126.com [School of Software and Communication Engineering, Xiangnan University, Chenzhou 423000 (China); Qiu, Feng; Huang, Jian-Quan; Deng, Hai-Ming; Yao, Min [Xiangnan University-Gospell Joint Laboratory of Microwave Communication Technology, Xiangnan University, Chenzhou 423000 (China)

    2016-04-29

    A novel phoxonic crystal using the piezoelectric (PMN-PT) and piezomagnetic (CoFe{sub 2}O{sub 4}) superlattices with three types of domains in a unit cell (PPSUC) is present, in which dual microwave photonic and phononic band gaps can be obtained simultaneously. Two categories of phononic band gaps, originating from both the Bragg scattering of acoustic waves in periodic structures at the Brillouin zone boundary and the electromagnetic wave-lattice vibration couplings near the Brillouin zone center, can be observed in the phononic band structures. The general characteristics of the microwave photonic band structures are similar to those of pure piezoelectric or piezomagnetic superlattices, with the major discrepancy being the appearance of nearly dispersionless branches within the microwave photonic band gaps, which show an extremely large group velocity delay. Thus, the properties may also be applied to compact acoustic-microwave devices. - Highlights: • Dual microwave photonic and phononic band gaps can coexist in the PPSUC. • Two categories of phononic band gaps with different mechanism can be obtained. • Nearly dispersionless branches appear in the microwave photonic band gaps.

  2. 1D-Var multilayer assimilation of X-band SAR data into a detailed snowpack model

    Science.gov (United States)

    Phan, X. V.; Ferro-Famil, L.; Gay, M.; Durand, Y.; Dumont, M.; Morin, S.; Allain, S.; D'Urso, G.; Girard, A.

    2014-10-01

    The structure and physical properties of a snowpack and their temporal evolution may be simulated using meteorological data and a snow metamorphism model. Such an approach may meet limitations related to potential divergences and accumulated errors, to a limited spatial resolution, to wind or topography-induced local modulations of the physical properties of a snow cover, etc. Exogenous data are then required in order to constrain the simulator and improve its performance over time. Synthetic-aperture radars (SARs) and, in particular, recent sensors provide reflectivity maps of snow-covered environments with high temporal and spatial resolutions. The radiometric properties of a snowpack measured at sufficiently high carrier frequencies are known to be tightly related to some of its main physical parameters, like its depth, snow grain size and density. SAR acquisitions may then be used, together with an electromagnetic backscattering model (EBM) able to simulate the reflectivity of a snowpack from a set of physical descriptors, in order to constrain a physical snowpack model. In this study, we introduce a variational data assimilation scheme coupling TerraSAR-X radiometric data into the snowpack evolution model Crocus. The physical properties of a snowpack, such as snow density and optical diameter of each layer, are simulated by Crocus, fed by the local reanalysis of meteorological data (SAFRAN) at a French Alpine location. These snowpack properties are used as inputs of an EBM based on dense media radiative transfer (DMRT) theory, which simulates the total backscattering coefficient of a dry snow medium at X and higher frequency bands. After evaluating the sensitivity of the EBM to snowpack parameters, a 1D-Var data assimilation scheme is implemented in order to minimize the discrepancies between EBM simulations and observations obtained from TerraSAR-X acquisitions by modifying the physical parameters of the Crocus-simulated snowpack. The algorithm then re

  3. Einstein X-ray observations of Herbig Ae/Be stars

    Science.gov (United States)

    Damiani, F.; Micela, G.; Sciortino, S.; Harnden, F. R., Jr.

    1994-01-01

    We have investigated the X-ray emission from Herbig Ae/Be stars, using the full set of Einstein Imaging Proportional Counter (IPC) observations. Of a total of 31 observed Herbig stars, 11 are confidently identified with X-ray sources, with four additonal dubious identifications. We have used maximum likelihood luminosity functions to study the distribution of X-ray luminosity, and we find that Be stars are significantly brighter in X-rays than Ae stars and that their X-ray luminosity is independent of projected rotational velocity v sin i. The X-ray emission is instead correlated with stellar bolometric luminosity and with effective temperature, and also with the kinetic luminosity of the stellar wind. These results seem to exclude a solar-like origin for the X-ray emission, a possibility suggested by the most recent models of Herbig stars' structure, and suggest an analogy with the X-ray emission of O (and early B) stars. We also observe correlations between X-ray luminosity and the emission at 2.2 microns (K band) and 25 microns, which strengthen the case for X-ray emission of Herbig stars originating in their circumstellar envelopes.

  4. Narrow-band tunable terahertz emission from ferrimagnetic Mn{sub 3-x}Ga thin films

    Energy Technology Data Exchange (ETDEWEB)

    Awari, N. [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden (Germany); University of Groningen, 9747 AG Groningen (Netherlands); Kovalev, S., E-mail: s.kovalev@hzdr.de, E-mail: c.fowley@hzdr.de, E-mail: rodek@tcd.ie; Fowley, C., E-mail: s.kovalev@hzdr.de, E-mail: c.fowley@hzdr.de, E-mail: rodek@tcd.ie; Green, B.; Yildirim, O.; Lindner, J.; Fassbender, J.; Deac, A. M.; Gensch, M. [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden (Germany); Rode, K., E-mail: s.kovalev@hzdr.de, E-mail: c.fowley@hzdr.de, E-mail: rodek@tcd.ie; Lau, Y.-C.; Betto, D.; Thiyagarajah, N.; Coey, J. M. D. [CRANN, AMBER and School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Gallardo, R. A. [Departamento de Física, Universidad Técnica Federico Santa María, Avenida España 1680, 2390123 Valparíso (Chile)

    2016-07-18

    Narrow-band terahertz emission from coherently excited spin precession in metallic ferrimagnetic Mn{sub 3-x}Ga Heusler alloy nanofilms has been observed. The efficiency of the emission, per nanometer film thickness, is comparable or higher than that of classical laser-driven terahertz sources based on optical rectification. The center frequency of the emission from the films can be tuned precisely via the film composition in the range of 0.20–0.35 THz, making this type of metallic film a candidate for efficient on-chip terahertz emitters. Terahertz emission spectroscopy is furthermore shown to be a sensitive probe of magnetic properties of ultra-thin films.

  5. 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.

  6. Simple calculation of hybridization effects in UTX and U2T2X compounds

    International Nuclear Information System (INIS)

    Prokes, K.; Brueck, E.; Nakotte, H.; De Chatel, P.F.; De Boer, F.R.

    1995-01-01

    The band widths of several UTX and U 2 T 2 X compounds (T: transition metal, X: p-metal) are evaluated by means of a tight-binding method. The magnetism in both groups of compounds is governed by the hybridization between U f-states and transition-metal d-states. Comparing the sum of all hybridization effects, we find approximately the same hybridization effects in both groups of compounds. We also observe a decrease of the band width with increasing atomic number Z within a transition-metal series. By comparing the band width with the theoretical critical energies for the f 3 and f 2 configurations, it is in some cases possible to predict whether the ground state is magnetically ordered or not. ((orig.))

  7. Lagrangian velocity correlations in homogeneous isotropic turbulence

    International Nuclear Information System (INIS)

    Gotoh, T.; Rogallo, R.S.; Herring, J.R.; Kraichnan, R.H.

    1993-01-01

    The Lagrangian velocity autocorrelation and the time correlations for individual wave-number bands are computed by direct numerical simulation (DNS) using the passive vector method (PVM), and the accuracy of the method is studied. It is found that the PVM is accurate when K max /k d ≥2 where K max is the maximum wave number carried in the simulation and k d is the Kolmogorov wave number. The Eulerian and Lagrangian time correlations for various wave-number bands are compared. At moderate to high wave number the Eulerian time correlation decays faster than the Lagrangian, and the effect of sweep on the former is observed. The time scale of the Eulerian correlation is found to be (kU 0 ) -1 while that of the Lagrangian is [∫ 0 k p 2 E(p)dp] -1/2 . The Lagrangian velocity autocorrelation in a frozen turbulent field is computed using the DIA, ALHDIA, and LRA theories and is compared with DNS measurements. The Markovianized Lagrangian renormalized approximation (MLRA) is compared with the DNS, and good agreement is found for one-time quantities in decaying turbulence at low Reynolds numbers and for the Lagrangian velocity autocorrelation in stationary turbulence at moderate Reynolds number. The effect of non-Gaussianity on the Lagrangian correlation predicted by the theories is also discussed

  8. MASS CALIBRATION AND COSMOLOGICAL ANALYSIS OF THE SPT-SZ GALAXY CLUSTER SAMPLE USING VELOCITY DISPERSION σ v AND X-RAY Y X MEASUREMENTS

    International Nuclear Information System (INIS)

    Bocquet, S.; Saro, A.; Mohr, J. J.; Bazin, G.; Chiu, I.; Desai, S.; Aird, K. A.; Ashby, M. L. N.; Bayliss, M.; Bautz, M.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T.; Brodwin, M.; Cho, H. M.; Clocchiatti, A.; De Haan, T.

    2015-01-01

    We present a velocity-dispersion-based mass calibration of the South Pole Telescope Sunyaev-Zel'dovich effect survey (SPT-SZ) galaxy cluster sample. Using a homogeneously selected sample of 100 cluster candidates from 720 deg 2 of the survey along with 63 velocity dispersion (σ v ) and 16 X-ray Y X measurements of sample clusters, we simultaneously calibrate the mass-observable relation and constrain cosmological parameters. Our method accounts for cluster selection, cosmological sensitivity, and uncertainties in the mass calibrators. The calibrations using σ v and Y X are consistent at the 0.6σ level, with the σ v calibration preferring ∼16% higher masses. We use the full SPT CL data set (SZ clusters+σ v +Y X ) to measure σ 8 (Ω m /0.27) 0.3 = 0.809 ± 0.036 within a flat ΛCDM model. The SPT cluster abundance is lower than preferred by either the WMAP9 or Planck+WMAP9 polarization (WP) data, but assuming that the sum of the neutrino masses is ∑m ν = 0.06 eV, we find the data sets to be consistent at the 1.0σ level for WMAP9 and 1.5σ for Planck+WP. Allowing for larger ∑m ν further reconciles the results. When we combine the SPT CL and Planck+WP data sets with information from baryon acoustic oscillations and Type Ia supernovae, the preferred cluster masses are 1.9σ higher than the Y X calibration and 0.8σ higher than the σ v calibration. Given the scale of these shifts (∼44% and ∼23% in mass, respectively), we execute a goodness-of-fit test; it reveals no tension, indicating that the best-fit model provides an adequate description of the data. Using the multi-probe data set, we measure Ω m = 0.299 ± 0.009 and σ 8 = 0.829 ± 0.011. Within a νCDM model we find ∑m ν = 0.148 ± 0.081 eV. We present a consistency test of the cosmic growth rate using SPT clusters. Allowing both the growth index γ and the dark energy equation-of-state parameter w to vary, we find γ = 0.73 ± 0.28 and w = –1.007 ± 0.065, demonstrating that the

  9. Electronic, magnetic and thermal properties of Co{sub 2}Cr{sub x}Fe{sub 1−x}X (X=Al, Si) Heusler alloys: First-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Guezlane, M. [Department of Physics, Faculty of Science, University of Batna, 05000 Batna (Algeria); Baaziz, H., E-mail: baaziz_hakim@yahoo.fr [Physics Department, Faculty of Science, University of M' sila, 28000 M' sila (Algeria); El Haj Hassan, F., E-mail: hassan.f@ul.edu.lb [Université Libanaise, Faculté des Sciences (I), Laboratoire de Physique et d’Electronique (LPE), Elhadath, Beirut (Lebanon); Charifi, Z. [Physics Department, Faculty of Science, University of M' sila, 28000 M' sila (Algeria); Djaballah, Y. [Laboratoire d’étude Physico-Chimique des Matériaux, Département de Physique, Faculté des Sciences, Université de Batna, Rue Chahid Boukhlouf, 05000 Batna (Algeria)

    2016-09-15

    Density functional theory (DFT) based on the full-potential linearized augmented plane wave (FP-LAPW) method is used to investigate the structural, electronic, magnetic and thermal properties of Co{sub 2}Cr{sub x}Fe{sub 1−x}X (X=Al, Si) full Heusler alloys, with L2{sub 1} structure. The structural properties and spin magnetic moments are investigated by the generalized gradient approximations (GGA) minimizing the total energy. For band structure calculations, GGA, the Engel–Vosko generalized gradient approximation (EVGGA) and modified Becke–Johnson (mBJ) schemes are used. Results of density of states (DOS) and band structures show that these alloys are half-metallic ferromagnets (HMFS). A regular-solution model has been used to investigate the thermodynamic stability of the compounds Co{sub 2}Cr{sub x}Fe{sub 1−x}X that indicates a phase miscibility gap. The thermal effects using the quasi-harmonic Debye model are investigated within the lattice vibrations. The temperature and pressure effects on the heat capacities, Debye temperatures and entropy are determined from the non-equilibrium Gibbs functions. - Highlights: • We present electronic, magnetic and thermal properties of Co{sub 2}Cr{sub x}Fe{sub 1−x}X (X=Al, Si) Heusler alloys. • The calculated phase diagram indicates a significant phase miscibility gap. • The computed band structures of ternary compounds using GGA, EVGGA and mBJ schemes indicate an indirect band gap (Γ-X) for the ternary compounds Co{sub 2}FeAl, Co{sub 2}CrAl, Co{sub 2}FeSi and Co{sub 2}CrSi while both alloys have a direct band gap. • The quasi-harmonic Debye model is successfully applied to determine the thermal properties.

  10. Band offsets of novel CoTiO{sub 3}/Ag{sub 3}VO{sub 4} heterojunction measured by X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wangkawong, Kanlayawat [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Tantraviwat, Doldet [Thai Microelectronics Center (TMEC), National Electronics and Computer Technology Center (NECTEC), Chachoengsao 24000 (Thailand); Phanichphant, Sukon [Materials Science Research Centre, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Inceesungvorn, Burapat, E-mail: binceesungvorn@gmail.com [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2015-01-01

    Highlights: • Band lineup of novel CoTiO{sub 3}/Ag{sub 3}VO{sub 4} composite is determined by semidirect XPS method. • The composite forms a type-II staggered heterojunction. • Valence and conduction-band offsets are 0.2 ± 0.3 and −0.6 ± 0.3 eV, respectively. • Band lineup determination is needed for understanding charge transfer at interfaces. - Abstract: The energy band diagram and band offsets of the novel CoTiO{sub 3}/Ag{sub 3}VO{sub 4} heterojunction photocatalyst are investigated by X-ray photoelectron spectroscopy for the first time. Excluding the strain effect, the valence-band and conduction-band offsets are determined to be 0.2 ± 0.3 eV and −0.6 ± 0.3 eV, respectively. The CoTiO{sub 3}/Ag{sub 3}VO{sub 4} composite forms a type-II heterojunction, for which the photogenerated charge carriers could be effectively separated. The results suggest that determination of the energy band structure is crucial for understanding the photogenerated charge transfer mechanism at the interfaces, hence the corresponding photocatalytic activity and would also be beneficial to the design of new and efficient heterostructure-based photocatalysts.

  11. Characterization of Melanin Radicals in Paraffin-embedded Malignant Melanoma and Nevus Pigmentosus Using X-band EPR and EPR Imaging.

    Science.gov (United States)

    Nakagawa, Kouichi; Minakawa, Satoko; Sawamura, Daisuke; Hara, Hideyuki

    2017-01-01

    Continuous wave electron paramagnetic resonance (CW EPR) and X-band (9 GHz) EPR imaging (EPRI) were used to nondestructively investigate the possible differentiation between malignant melanoma (MM) and nevus pigmentosus (NP) melanin radicals in paraffin-embedded specimens. The EPR spectra of both samples were analyzed using linewidth, spectral pattern, and X-band EPRI. The CW-EPR spectra of the MM showed an additional signal overlap. Eumelanin- and pheomelanin-related radicals were observed in the MM specimens. The EPR results revealed that the peak-to-peak linewidths (ΔH pp ) of paraffin-embedded MM and NP samples were 0.65 ± 0.01 and 0.69 ± 0.01 mT, respectively. The g-value was 2.005 for both samples. Moreover, the two-dimensional (2D) EPRI of the MM showed different signal intensities at the different tumor stages, unlike the NP, which displayed fewer variations in signal intensity. Thus, the present results suggest that EPR and 2D EPRI can be useful for characterization of the two melanin radicals in the MM and for determination of their size and concentration.

  12. Treatment of Patellar Lower Pole Fracture with Modified Titanium Cable Tension Band Plus Patellar Tibial Tunnel Steel "8" Reduction Band.

    Science.gov (United States)

    Li, Jiaming; Wang, Decheng; He, Zhiliang; Shi, Hao

    2018-01-08

    To determine the efficacy of modified titanium tension band plus patellar tendon tunnel steel 8 "reduction band" versus titanium cable tension band fixation for the treatment of patellar lower pole fracture. 58 patients with lower patella fracture were enrolled in this study, including 30 patients treated with modified titanium cable tension band plus patellar tibial tunnel wire "8" tension band internal fixation (modified group), and 28 patients with titanium cable tension band fixation. All patients were followed up for 9∼15 months with an average of 11.6 months. Knee flexion was significantly improved in the modified group than in the titanium cable tension band group (111.33 ± 13 degrees versus 98.21 ± 21.70 degrees, P = 0.004). The fracture healing time showed no significant difference. At the end of the follow-up, the improvement excellent rate was 93.33% in the modified group, and 82.14% in the titanium cable tension band group. Titanium cable tension band internal fixation loosening was found in 2 cases, including 1 case of treatment by two surgeries without loose internal fixation. The modified titanium cable tension band with "8" tension band fixation showed better efficacy for lower patella fractures than titanium cable tension band fixation.

  13. Design of 6 MeV X-band electron linac for dual-head gantry radiotherapy system

    Science.gov (United States)

    Shin, Seung-wook; Lee, Seung-Hyun; Lee, Jong-Chul; Kim, Huisu; Ha, Donghyup; Ghergherehchi, Mitra; Chai, Jongseo; Lee, Byung-no; Chae, Moonsik

    2017-12-01

    A compact 6 MeV electron linac is being developed at Sungkyunkwan University, in collaboration with the Korea atomic energy research institute (KAERI). The linac will be used as an X-ray source for a dual-head gantry radiotherapy system. X-band technology has been employed to satisfy the size requirement of the dual-head gantry radiotherapy machine. Among the several options available, we selected a pi/2-mode, standing-wave, side-coupled cavity. This choice of radiofrequency (RF) cavity design is intended to enhance the shunt impedance of each cavity in the linac. An optimum structure of the RF cavity with a high-performance design was determined by applying a genetic algorithm during the optimization procedure. This paper describes the detailed design process for a single normal RF cavity and the entire structure, including the RF power coupler and coupling cavity, as well as the beam dynamics results.

  14. Operational Bright-Band Snow Level Detection Using Doppler Radar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A method to detect the bright-band snow level from radar reflectivity and Doppler vertical velocity data collection with an atmospheric profiling Doppler radar. The...

  15. Probing the graphite band structure with resonant soft-x-ray fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Carlisle, J.A.; Shirley, E.L.; Hudson, E.A. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Soft x-ray fluorescence (SXF) spectroscopy using synchrotron radiation offers several advantages over surface sensitive spectroscopies for probing the electronic structure of complex multi-elemental materials. Due to the long mean free path of photons in solids ({approximately}1000 {angstrom}), SXF is a bulk-sensitive probe. Also, since core levels are involved in absorption and emission, SXF is both element- and angular-momentum-selective. SXF measures the local partial density of states (DOS) projected onto each constituent element of the material. The chief limitation of SXF has been the low fluorescence yield for photon emission, particularly for light elements. However, third generation light sources, such as the Advanced Light Source (ALS), offer the high brightness that makes high-resolution SXF experiments practical. In the following the authors utilize this high brightness to demonstrate the capability of SXF to probe the band structure of a polycrystalline sample. In SXF, a valence emission spectrum results from transitions from valence band states to the core hole produced by the incident photons. In the non-resonant energy regime, the excitation energy is far above the core binding energy, and the absorption and emission events are uncoupled. The fluorescence spectrum resembles emission spectra acquired using energetic electrons, and is insensitive to the incident photon`s energy. In the resonant excitation energy regime, core electrons are excited by photons to unoccupied states just above the Fermi level (EF). The absorption and emission events are coupled, and this coupling manifests itself in several ways, depending in part on the localization of the empty electronic states in the material. Here the authors report spectral measurements from highly oriented pyrolytic graphite.

  16. Constructing anisotropic single-Dirac-cones in Bi(1-x)Sb(x) thin films.

    Science.gov (United States)

    Tang, Shuang; Dresselhaus, Mildred S

    2012-04-11

    The electronic band structures of Bi(1-x)Sb(x) thin films can be varied as a function of temperature, pressure, stoichiometry, film thickness, and growth orientation. We here show how different anisotropic single-Dirac-cones can be constructed in a Bi(1-x)Sb(x) thin film for different applications or research purposes. For predicting anisotropic single-Dirac-cones, we have developed an iterative-two-dimensional-two-band model to get a consistent inverse-effective-mass-tensor and band gap, which can be used in a general two-dimensional system that has a nonparabolic dispersion relation as in the Bi(1-x)Sb(x) thin film system. © 2012 American Chemical Society

  17. Higher‐order mode absorption measurement of X-band choke-mode cavities in a radial line structure

    International Nuclear Information System (INIS)

    Zha, Hao; Shi, Jiaru; Wu, Xiaowei; Chen, Huaibi

    2016-01-01

    An experiment is presented to study the higher-order mode (HOM) suppression of X-band choke-mode structures with a vector network analyzer (VNA). Specific radial line disks were built to test the reflection from the corresponding damping load and different choke geometries. The mismatch between the radial lines and the VNA was calibrated through a special multi-short-load calibration method. The measured reflections of different choke geometries showed good agreement with the theoretical calculations and verified the HOM absorption feature of each geometric design.

  18. Higher‐order mode absorption measurement of X-band choke-mode cavities in a radial line structure

    Energy Technology Data Exchange (ETDEWEB)

    Zha, Hao [Department of Engineering Physics, Tsinghua University, Beijing CN-100086 (China); Key Laboratory of Particle and Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China); The European Organization for Nuclear Research, Geneva CH-1211 (Switzerland); Shi, Jiaru, E-mail: shij@mail.tsinghua.edu.cn [Department of Engineering Physics, Tsinghua University, Beijing CN-100086 (China); Key Laboratory of Particle and Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China); The European Organization for Nuclear Research, Geneva CH-1211 (Switzerland); Wu, Xiaowei; Chen, Huaibi [Department of Engineering Physics, Tsinghua University, Beijing CN-100086 (China); Key Laboratory of Particle and Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China)

    2016-04-01

    An experiment is presented to study the higher-order mode (HOM) suppression of X-band choke-mode structures with a vector network analyzer (VNA). Specific radial line disks were built to test the reflection from the corresponding damping load and different choke geometries. The mismatch between the radial lines and the VNA was calibrated through a special multi-short-load calibration method. The measured reflections of different choke geometries showed good agreement with the theoretical calculations and verified the HOM absorption feature of each geometric design.

  19. Development of a High Resolution X-Ray Imaging Crystal Spectrometer for Measurement of Ion-Temperature and Rotation-Velocity Profiles in Fusion Energy Research Plasmas

    International Nuclear Information System (INIS)

    Hill, K.W.; Bitter, M.L.; Broennimann, Ch.; Eikenberry, E.F.; Ince-Cushman, A.; Lee, S.G.; Rice, J.E.; Scott, S.; Barnsley, R.

    2008-01-01

    A new imaging high resolution x-ray crystal spectrometer (XCS) has been developed to measure continuous profiles of ion temperature and rotation velocity in fusion plasmas. Following proof-of-principle tests on the Alcator C-Mod tokamak and the NSTX spherical tokamak, and successful testing of a new silicon, pixilated detector with 1MHz count rate capability per pixel, an imaging XCS is being designed to measure full profiles of T i and ν φ on C-Mod. The imaging XCS design has also been adopted for ITER. Ion-temperature uncertainty and minimum measurable rotation velocity are calculated for the C-Mod spectrometer. The affects of x-ray and nuclear-radiation background on the measurement uncertainties are calculated to predict performance on ITER

  20. A semi-urban case study of small scale variability of rainfall and run-off, with C- and X-band radars and the fully distributed hydrological model Multi-Hydro

    Science.gov (United States)

    Alves de Souza, Bianca; da Silva Rocha Paz, Igor; Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel

    2016-04-01

    The complexity of urban hydrology results both from that of urban systems and the extreme rainfall variability. The latter can display strongly localised rain cells that can be extremely damaging when hitting vulnerable parts of urban systems. This paper investigates this complexity on a semi-urban sub-catchment - located in Massy (South of Paris, France) - of the Bievre river, which is known for its frequent flashfloods. Advanced geo-processing techniques were used to find the ideal pixel size for this 6.326km2 basin. C-band and X-band radar data are multifractally downscaled at various resolutions and input to the fully distributed hydrological model Multi-Hydro. The latter has been developed at Ecole des Ponts ParisTech. It integrates validated modules dealing with surface flow, saturated and unsaturated surface flow, and sewer flow. The C-band radar is located in Trappes, approx. 21km East of the catchment, is operated by Méteo-France and has a resolution of 1km x 1km x 5min. The X-band radar operated by Ecole des Ponts Paris Tech on its campus has a resolution of 125m x 125m x 3.4min. The performed multifractal downscaling enables both the generation of large ensemble realizations and easy change of resolution (e.g. down to 10 m in the present study). This in turn allows a detailed analysis of the impacts of small scale variability and the required resolution to obtain accurate simulations, therefore predictions. This will be shown on two rainy episodes over the chosen sub-catchment of the Bievre river.

  1. X - Band EPR Study on Poly(Li-2-Hydroxyethyl Methacrylate)-Co-Poly(4-Vinly Pyridine)

    International Nuclear Information System (INIS)

    Usta, A.

    2008-01-01

    Some copolymers have important properties that it is alter rapidly from a liquid to a solid state when an external electric field is applied. In this study, the polymer was synthesized by six ionomers with different molar masses. The polymer has been irradiated with 60 C o - γ rays at room temperature along three days. After irradiation, the material has been investigated by X-band Electron Spin Resonance (ESR) spectrometer at various conditions. A very intensity ESR peaks have been observed at temperature between 130-450K along with that displayed, this ESR peaks were changed with temperature and produced radical was stable

  2. ROSAT: X ray survey of compact groups

    NARCIS (Netherlands)

    van Gorkom, Jacqueline

    1993-01-01

    This is the final technical report on grant NAG5-1954, which was awarded under the NASA ROSAT Guest Investigator Program to Columbia University. This grant was awarded for a number of projects on two rather different topics: (1) an x-ray survey of compact groups of galaxies; and (2) the fate of gas

  3. Analysis of the swimming velocity of cadmium-stressed Daphnia magna

    International Nuclear Information System (INIS)

    Baillieul, M.; Blust, R.

    1999-01-01

    The swimming velocity of the waterflea Daphnia magna is dependent on its body size. Therefore, environmental factors like toxic stress that influence growth also influence swimming velocity. An experiment was set up to test whether exposure to cadmium would reduce only growth, with a concomitant decrease in velocity, or whether it would reduce velocity below the swimming velocity of similarly-sized control animals. Daphnids were exposed for 10 days to free cadmium ion concentrations ranging from 1x10 -8 to 1x10 -7 M Cd 2+ , and body size and swimming velocity were measured every 2 days. The results showed that cadmium decreased both growth and velocity, i.e. exposed daphnids swam slower than similarly-sized control daphnids. Swimming velocity provided no indication of successful acclimation in any cadmium treatment. Food consumption and assimilation were reduced by exposure to cadmium. This reduced food intake may have, at least partially, caused the decreased growth rates. However, since reduced food intake does not affect swimming velocity, the reduced swimming velocity must be attributed to toxic effects of cadmium, other than those on food intake. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  4. 3D Vector Velocity Estimation using a 2D Phased Array

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Jensen, Jørgen Arendt

    2011-01-01

    of using the TO method for estimation 3D velocity vectors, and the proposed decoupling is demonstrated. A 64x64 and a 32x32 elements transducer are emulated using Field II. Plug flow with a speed of 1 m/s in a small region is rotated in the XY -plane. A binary flow example with [vx,vy]=[1,0] and [0,1] m......A method to estimate the three dimensional (3D) velocity vector is presented is this paper. 3D velocity vector techniques are needed to measure the full velocity and characterize the complicated flow patterns in the human body. The Transverse Oscillation (TO) method introduces oscillations...... matrix transducer. For the 32x32 transducer, the mean and standard deviation for the speed are 0.94 0.11 m/s and for the angle bias -0.487.7. The simulation study clearly demonstrates, that the new method can be used to estimate the 3D velocity vector using a 2D phased matrix array, and that the velocity...

  5. 182Pt as a possible candidate for X(5) symmetry

    International Nuclear Information System (INIS)

    Petkov, P; Gladnsihki, K A; Dewald, A; Fransen, C; Hackstein, M; Jolie, J; Pissulla, Th; Rother, W; Zell, K O

    2012-01-01

    Recently, a new island of X(5) nuclei has been suggested around A=180 exemplified by some Osmium isotopes. To investigate the limits of its region, a Recoil-distance Doppler shift lifetime measurement has been performed for 182 Pt. For the data analysis, the Differential decay curve method has been applied in a newly developed version convenient for low recoil velocities and a non-negligible fraction of nuclei stopped already in the target. The level energies and the newly deduced transition quadrupole moments in the yrast band reveal the persistence of X(5) features in the investigated nucleus, but other spectroscopic data and IBM and GCM calculations indicate shape coexistence and a position of 182 Pt close but not at the critical point of the shape-transition.

  6. Electron velocity map imaging and theoretical study on CuXH (X = O and S) anions

    Science.gov (United States)

    Qin, Zhengbo; Wang, Hui; Ren, Yangdi; Zheng, Xianfeng; Cui, Zhifeng; Tang, Zichao

    2018-01-01

    Vibrationally resolved photoelectron spectra of CuOH- and CuSH- have been determined via velocity map imaging method to investigate the transitions of X1A‧ ← X2A‧ at 532 nm. Adiabatic detachment energies of CuOH- and CuSH- are assigned to 0.995(12) and 1.098(12) eV, respectively. Combined theoretical calculations with Franck-Condon simulations, it allows extracting the vibrational frequencies in neutral, which yields 629(32) cm-1 with Cusbnd O stretching mode and 387(24) cm-1 with Cusbnd S stretching mode for CuXH (X = O and S). Parallel transition properties of photoelectron angular distributions (PADs) for both species are correlated to the photodetachment of SOMO orbitals, which mainly involved in the Cu atom s orbital and partial s orbital in other atoms. Based on chemical bonding analyses (Wiberg, NAO, Mayer, NRT, and ELF), it is suggested that a trend is observed with a subtle variation of covalent component from weak covalent behavior between Cusbnd O in CuOH-1/0 to stronger covalent bonding between Cusbnd S in CuSH-1/0 (especially for non-ignorable covalent component in CuSH species) though ionic bonding dominates both in Cusbnd O and Cusbnd S bonds for the two systems.

  7. Application of Artificial Neural Networks to Ship Detection from X-Band Kompsat-5 Imagery

    Directory of Open Access Journals (Sweden)

    Jeong-In Hwang

    2017-09-01

    Full Text Available For ship detection, X-band synthetic aperture radar (SAR imagery provides very useful data, in that ship targets look much brighter than surrounding sea clutter due to the corner-reflection effect. However, there are many phenomena which bring out false detection in the SAR image, such as noise of background, ghost phenomena, side-lobe effects and so on. Therefore, when ship-detection algorithms are carried out, we should consider these effects and mitigate them to acquire a better result. In this paper, we propose an efficient method to detect ship targets from X-band Kompsat-5 SAR imagery using the artificial neural network (ANN. The method produces the ship-probability map using ANN, and then detects ships from the ship-probability map by using a threshold value. For the purpose of getting an improved ship detection, we strived to produce optimal input layers used for ANN. In order to reduce phenomena related to the false detections, the non-local (NL-means filter and median filter were utilized. The NL-means filter effectively reduced noise on SAR imagery without smoothing edges of the objects, and the median filter was used to remove ship targets in SAR imagery. Through the filtering approaches, we generated two input layers from a Kompsat-5 SAR image, and created a ship-probability map via ANN from the two input layers. When the threshold value of 0.67 was imposed on the ship-probability map, the result of ship detection from the ship-probability map was a 93.9% recall, 98.7% precision and 6.1% false alarm rate. Therefore, the proposed method was successfully applied to the ship detection from the Kompsat-5 SAR image.

  8. ACCURATE LABORATORY WAVELENGTHS OF THE e 3 Σ-(ν' = 5) - X 1 Σ+(ν'' = 0) BAND OF 12C16O

    International Nuclear Information System (INIS)

    Dickenson, G. D.; Nortje, A. C.; Steenkamp, C. M.; Rohwer, E. G.; Du Plessis, A.

    2010-01-01

    The forbidden singlet-triplet transitions of carbon monoxide (CO) are important in the interpretation of vacuum ultraviolet interstellar absorption spectra and in particular for the measurement of large CO column densities. Twenty rovibronic lines of the e 3 Σ - (ν' = 5) - X 1 Σ + (ν'' = 0) band of 12 C 16 O for which laboratory wavelengths were previously unavailable were identified in laser-induced fluorescence excitation spectra. Wavelengths were assigned to five rovibronic transitions to an average accuracy of 0.0028 A. A further 15 lines could not be fully resolved and average wavelengths were measured for these groups of closely spaced lines. A wavelength difference of 0.011 ± 0.0028 A between the measured wavelengths and the calculated wavelengths in the atlas of Eidelsberg and Rostas demonstrates the need for more experimental data on CO.

  9. Accurate Laboratory Wavelengths of the e 3 Σ-(ν' = 5) - X 1 Σ+(ν'' = 0) Band of 12C16O

    Science.gov (United States)

    Dickenson, G. D.; Nortje, A. C.; Steenkamp, C. M.; Rohwer, E. G.; Du Plessis, A.

    2010-05-01

    The forbidden singlet-triplet transitions of carbon monoxide (CO) are important in the interpretation of vacuum ultraviolet interstellar absorption spectra and in particular for the measurement of large CO column densities. Twenty rovibronic lines of the e 3Σ-(ν' = 5) - X 1Σ+(ν'' = 0) band of 12 C 16O for which laboratory wavelengths were previously unavailable were identified in laser-induced fluorescence excitation spectra. Wavelengths were assigned to five rovibronic transitions to an average accuracy of 0.0028 Å. A further 15 lines could not be fully resolved and average wavelengths were measured for these groups of closely spaced lines. A wavelength difference of 0.011 ± 0.0028 Å between the measured wavelengths and the calculated wavelengths in the atlas of Eidelsberg & Rostas demonstrates the need for more experimental data on CO.

  10. A Multi-Polarization Study on Ship Detection over X-Band Full-Resolution COSMO SkyMed SAR Data

    Science.gov (United States)

    Migliaccio, Maurizio; Nunziata, Ferdinando; Sorrentio, Antonio; Ferrara, Giuseppe

    2011-03-01

    Ship detection over marine Synthetic Aperture Radar (SAR) images is a key application for global monitoring for environment and security. In this paper, a physically-based filter which exploits a proper combination of GK parameters is conceived to unambiguously observe ships over sea surface in HV-polarized Single Look Complex (SLC) SAR data. Experiments accomplished over a meaningful set of X-band SLC CosmoSkyMed StripMap SAR data confirm the physical soundness of the proposed approach.

  11. Investigation of factors influencing the efficacy of electromagnetic shielding in X band frequency range

    Directory of Open Access Journals (Sweden)

    Vida Zaroushani

    2016-12-01

    Full Text Available Introduction: Due to the importance of engineering controls for prevention of microwave exposure, this study was conducted to design and constract a novel electromagnetic shielding and also to examine the factors influencing shielding efficacy in X band frequency range. Material and Method: This study used Resin Epoxy as matrix and nano-Nickel Oxide as filler to prepare the composite plates with three different thicknesses (2,4, and 6 mm and four different weight percentages (5,7,9 and 11. The fabricated composites characterized using X-ray diffraction and Field Emission Scanning Electron microscopy. Shielding effectiveness, percolation depth, and percolation threshold were measured using Vector Network Analyzers. Thermal Gravimetric Analysis was conducted to study the temperature influence on weight loss for fabricated composites. Result: A maximum shielding effectiveness value of 84.18% was obtained for the 11%-6mm composite at 8.01 GHz and the 7%-4mm composite exhibits a higher average of shielding effectiveness of 66.72% at X- band frequency range. The 4mm thickness was optimum and critical diameter for composite plates; and percolation depth was obtained greater than thickness of composites. However, increasing the nickel oxide content did not show noticeable effect on the shielding effectiveness. Thermal Gravimetric Analysis showed that the study shields were resistant to temperature up to 150 °C without experiencing weight loss. What is more, the results indicated that Nickel oxide Nano particles had desirable distribution and dispersion in epoxy matrix and percolation threshold was appeared in low content of nickel oxide nanoparticles. Conclusion: A novel electromagnetic shield using low thickness and few content of nanoparticle with noticeable efficacy was properly designed and constructed in the field of occupational health. In addition, this shield has low cost, easy to manufacture, resistance to wet/corrosion, and low weight. Epoxy

  12. Statistics of a mixed Eulerian-Lagrangian velocity increment in fully developed turbulence

    International Nuclear Information System (INIS)

    Friedrich, R; Kamps, O; Grauer, R; Homann, H

    2009-01-01

    We investigate the relationship between Eulerian and Lagrangian probability density functions obtained from numerical simulations of two-dimensional as well as three-dimensional turbulence. We show that in contrast to the structure functions of the Lagrangian velocity increment δ τ v(y)=u(x(y, τ), τ)- u(y, 0), where u(x, t) denotes the Eulerian velocity and x(y, t) the particle path initially starting at x(y, 0)=y, the structure functions of the velocity increment δ τ w(y)=u(x(y, τ), τ)- u(y, τ) exhibit a wide range of scaling behavior. Similar scaling indices are detected for the structure functions for particles diffusing in frozen turbulent fields. Furthermore, we discuss a connection to the scaling of Eulerian transversal structure functions.

  13. Analyzing shear band formation with high resolution X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Pagan, Darren C.; Obstalecki, Mark; Park, Jun-Sang; Miller, Matthew P.

    2018-04-01

    Localization of crystallographic slip into shear bands during uniaxial compression of a copper single crystal is studied using very far-field high-energy diffraction microscopy (vff-HEDM). Diffracted intensity was collected in-situ as the crystal deformed using a unique mobile detector stage that provided access to multiple diffraction peaks with high-angular resolution. From the diffraction data, single crystal orientation pole figures (SCPFs) were generated and are used to track the evolution of the distribution of lattice orientation that develops as slip localizes. To aid the identification of 'signatures' of shear band formation and analyze the SCPF data, a model of slip-driven lattice reorientation within shear bands is introduced. Confidence is built in conclusions drawn from the SCPF data about the character of internal slip localization through comparisons with strain fields on the sample surface measured simultaneously using digital image correlation. From the diffraction data, we find that the active slip direction and slip plane are not directly aligned with the orientation of the shear bands that formed. In fact, by extracting the underlying slip system activity from the SCPF data, we show that intersecting shear bands measured on the surface of the sample arise from slip primarily on the same underlying single slip system. These new vff-HEDM results raise significant questions on the use of surface measurements for slip system activity estimation. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  14. Local liquid velocity measurement of Trickle Bed Reactor using Digital Industrial X-ray Radiography

    Science.gov (United States)

    Mohd Salleh, Khairul Anuar

    Trickle Bed Reactors (TBRs) are fixed beds of particles in which both liquid and gas flow concurrently downward. They are widely used to produce not only fuels but also lubrication products. The measurement and the knowledge of local liquid velocities (VLL) in TBRs is less which is essential for advancing the understanding of its hydrodynamics and for validation computational fluid dynamics (CFD). Therefore, this work focused on developing a new, non-invasive, statistically reliable technique that can be used to measure local liquid velocity (VLL) in two-dimensions (2-D). This is performed by combining Digital Industrial X-ray Radiography (DIR) and Particle Tracking Velocimetry (PTV) techniques. This work also make possible the development of three-dimensional (3-D) VLL measurements that can be taken in TBRs. Measurements taken through both the combined and the novel technique, once validated, were found to be comparable to another technique (a two-point fiber optical probe) currently being developed at Missouri University of Science and Technology. The results from this study indicate that, for a gas-liquid-solid type bed, the measured VLL can have a maximum range that is between 35 and 51 times that of its superficial liquid velocity (VSL). Without the existence of gas, the measured VLL can have a maximum range that is between 4 and 4.7 times that of its VSL. At a higher V SL, the particle tracer was greatly distributed and became carried away by a high liquid flow rate. Neither the variance nor the range of measured VLL varied for any of the replications, confirming the reproducibility of the experimental measurements used, regardless of the VSL . The liquid's movement inside the pore was consistent with findings from previous studies that used various techniques.

  15. Commissioning of the First Klystron-Based X-Band Power Source at CERN

    CERN Document Server

    Kovermann, J; Curt, S; Doebert, S; Naon, M; McMonagle, G; Paju, E; Rey, S; Riddone, G; Schirm, K; Syratchev, I; Timeo, L; Wuensch, W; Hamdi, A; Peauger, FF; Eichner, J; Haase, A; Sprehn, D

    2012-01-01

    A new klystron based X-band rf power source operating at 11.994 GHz has been installed and started to be commissioned at CERN in collaboration with CEA Saclay and SLAC for CLIC accelerating structure tests. The system comprises a solid state high voltage modulator, an XL5 klystron developed by SLAC, a cavity based SLED type pulse compressor, the necessary low level rf system including rf diagnostics and interlocks and the surrounding vacuum, cooling and controls infrastructure. The system is designed to produce up to 50 MW rf pulses of 1500 ns pulse width and 50 Hz repetition rate. After pulse compression, up to 100 MW of rf power at 250 ns pulse width will be available in the structure test bunker. This paper describes in more detail this setup and the process of commissioning which is necessary to arrive at the design performance.

  16. Low-loss negative index metamaterials for X, Ku, and K microwave bands

    Directory of Open Access Journals (Sweden)

    David A. Lee

    2015-04-01

    Full Text Available Low-loss, negative-index of refraction metamaterials were designed and tested for X, Ku, and K microwave frequency bands. An S-shaped, split-ring resonator was used as a unit cell to design homogeneous slabs of negative-index metamaterials. Then, the slabs of metamaterials were cut unto prisms to measure experimentally the negative index of refraction of a plane electromagnetic wave. Theoretical simulations using High-Frequency Structural Simulator, a finite element equation solver, were in good agreement with experimental measurements. The negative index of refraction was retrieved from the angle- and frequency-dependence of the transmitted intensity of the microwave beam through the metamaterial prism and compared well to simulations; in addition, near-field electromagnetic intensity mapping was conducted with an infrared camera, and there was also a good match with the simulations for expected frequency ranges for the negative index of refraction.

  17. A Multiwavelength Study of Cygnus X-3

    Science.gov (United States)

    McCollough, M. L; Robinson, C. R.; Zhang, S. N.; Paciesas, W. S.; Harmon, B. A.; Hjellming, R. M.; Rupen, M.; Waltman, E. B.; Foster, R. S.; Ghigo, F. D.

    1997-01-01

    We present a global comparison of long term observations of the hard X-ray (20-100 keV), soft X-ray (1.5-12 keV), infrared (1-2 micron) and radio (2.25, 8.3 and 15 GHz) bands for the unusual X-ray binary Cygnus X-3. Data were obtained in the hard X-ray band from CGRO/BATSE, in the soft X-ray band from Rossi Xray Timing Explorer (RXTE)/ASM, in the radio band from the Green Bank Interferometer and Ryle Telescope and in the infrared band from various ground based observatories. Radio flares, quenched radio states and quiescent radio emission can all be associated with changes in the hard and soft X-ray intensity. The injection of plasma into the radio jet is directly related to changes in the hard and soft X-ray emission. The infrared observations are examined in the context of these findings.

  18. S-Wave's Velocities of the Lithosphere-Asthenosphere System in the Caribbean Region

    International Nuclear Information System (INIS)

    Gonzalez, O'Leary; Alvarez, Jose Leonardo; Moreno, Bladimir; Panza, Giuliano F.

    2010-06-01

    An overview of the S-wave velocity (Vs) structural model of the Caribbean is presented with a resolution of 2 o x2 o . As a result of the frequency time analysis (FTAN) of more than 400 trajectories epicenter-stations in this region, new tomographic maps of Rayleigh waves group velocity dispersion at periods ranging from 10 s to 40 s have been determined. For each 2 o x2 o cell, group velocity dispersion curves were determined and extended to 150 s adding data from a larger scale tomographic study (Vdovin et al., 1999). Using, as independent a priori information, the available geological and geophysical data of the region, each dispersion curve has been mapped, by non-linear inversion, into a set of Vs vs. depth models in the depth range from 0 km to 300 km. Due to the non-uniqueness of the solutions for each cell a Local Smoothness Optimization (LSO) has been applied to the whole region to identify a tridimensional model of Vs vs. depth in cells of 2 o x2 o , thus satisfying the Occam razor concept. Through these models some main features of the lithosphere and asthenosphere are evidenced, such as: the west directed subduction zone of the eastern Caribbean region with a clear mantle wedge between the Caribbean lithosphere and the subducted slab; the complex and asymmetric behavior of the crustal and lithospheric thickness in the Cayman ridge; the diffused presence of oceanic crust in the region; the presence of continental type crust in the South America, Central America and North America plates, as well as the bottom of the upper asthenosphere that gets shallower going from west to east. (author)

  19. Suicide rates in five-year age-bands after the age of 60 years

    DEFF Research Database (Denmark)

    Shah, Ajit; Bhat, Ravi; Zarate-Escudero, Sofia

    2016-01-01

    -79 years) and the oldest old (80+ years) age groups. METHODS: Data on the number of suicides (International Classification of Diseases - ICD-10 codes, X60-84) in each of the eight five-year age-bands between the age-bands 60-64 years and 95-99 years in both gender for as many years as possible from 2000...... were ascertained from three sources: colleagues with access to national data, national statisics office websites and email contact with the national statistics offices. The population size for the corresponding years and age-bands was estimated for each country using data provided by the United Nations......BACKGROUND: There is paucity of studies examining suicide rates in narrow five-year age-bands after the age of 60 years. This study examined suicide rates in eight five-year age-bands between the age of 60 and 99 years because this will allow more precise comparison between the young old (60...

  20. Corrosion and erosion monitoring in plates and pipes using constant group velocity Lamb wave inspection.

    Science.gov (United States)

    Nagy, Peter B; Simonetti, Francesco; Instanes, Geir

    2014-09-01

    Recent improvements in tomographic reconstruction techniques generated a renewed interest in short-range ultrasonic guided wave inspection for real-time monitoring of internal corrosion and erosion in pipes and other plate-like structures. Emerging evidence suggests that in most cases the fundamental asymmetric A0 mode holds a distinct advantage over the earlier market leader fundamental symmetric S0 mode. Most existing A0 mode inspections operate at relatively low inspection frequencies where the mode is highly dispersive therefore very sensitive to variations in wall thickness. This paper examines the potential advantages of increasing the inspection frequency to the so-called constant group velocity (CGV) point where the group velocity remains essentially constant over a wide range of wall thickness variation, but the phase velocity is still dispersive enough to allow accurate wall thickness assessment from phase angle measurements. This paper shows that in the CGV region the crucial issue of temperature correction becomes especially simple, which is particularly beneficial when higher-order helical modes are also exploited for tomography. One disadvantage of working at such relatively high inspection frequency is that, as the slower A0 mode becomes faster and less dispersive, the competing faster S0 mode becomes slower and more dispersive. At higher inspection frequencies these modes cannot be separated any longer based on their vibration polarization only, which is mostly tangential for the S0 mode while mostly normal for the A0 at low frequencies, as the two modes become more similar as the frequency increases. Therefore, we propose a novel method for suppressing the unwanted S0 mode based on the Poisson effect of the material by optimizing the angle of inclination of the equivalent transduction force of the Electromagnetic Acoustic Transducers (EMATs) used for generation and detection purposes. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. A Planar UWB Antenna with Switchable Single/Double Band-Rejection Characteristics

    Directory of Open Access Journals (Sweden)

    V. Sharbati

    2016-09-01

    Full Text Available In this Paper, a reconfigurable antenna with capability to operate in the ultrawideband (UWB mode from 2.85 to 14.4 GHz with switchable notch bands of 3.25–4.26 GHz, 5.1–5.9 GHz or 7.1-7.8 GHz, is presented. The proposed antenna has a simple configuration and compact size of 17 × 14 mm2. To make the band-notches, three methods (methods of slot antenna, parasitic patches and backplane structure are used. To achieve the reconfigurability, three PIN diode are placed on the proposed antenna. A PIN diode is inserted over the L-shaped parasitic element and the rectangular patch, another one is placed between the two parasitic elements on the ground plane, and other across the square ring-shaped slot, respectively. Antenna performance can be changed by adjusting the status of the PIN diodes that make the band-notches in applications bands (WLAN, WiMAX/C-band and X-band. Good group delay and monopole-like radiation pattern characteristics are achieved in the frequency band of interest. The antenna performance both by simulation and by experiment indicates that it is suitable and a good candidate for UWB applications.

  2. Population genetic study of 34 X-Chromosome markers in 5 main ethnic groups of China.

    Science.gov (United States)

    Zhang, Suhua; Bian, Yingnan; Li, Li; Sun, Kuan; Wang, Zheng; Zhao, Qi; Zha, Lagabaiyila; Cai, Jifeng; Gao, Yuzhen; Ji, Chaoneng; Li, Chengtao

    2015-12-04

    As a multi-ethnic country, China has some indigenous population groups which vary in culture and social customs, perhaps as a result of geographic isolation and different traditions. However, upon close interactions and intermarriage, admixture of different gene pools among these ethnic groups may occur. In order to gain more insight on the genetic background of X-Chromosome from these ethnic groups, a set of X-markers (18 X-STRs and 16 X-Indels) was genotyped in 5 main ethnic groups of China (HAN, HUI, Uygur, Mongolian, Tibetan). Twenty-three private alleles were detected in HAN, Uygur, Tibetan and Mongolian. Significant differences (p population differentiation of HUI and Uygur. However, the HAN, Tibetan and Mongolian ethnic groups were closely clustered. Eighteen X-Indels exhibited in general congruent phylogenetic signal and similar cluster among the 5 ethnic groups compared with 16 X-STRs. Aforementioned results proved the genetic polymorphism and potential of the 34 X-markers in the 5 ethnic groups.

  3. Calculation of band alignments and quantum confinement effects in zero- and one-dimensional pseudomorphic structures

    International Nuclear Information System (INIS)

    Yang, M.; Sturm, J.C.; Prevost, J.

    1997-01-01

    The strain field distributions and band lineups of zero-dimensional and one-dimensional strained pseudomorphic semiconductor particles inside a three-dimensional matrix of another semiconductor have been studied. The resulting strain in the particle and the matrix leads to band alignments considerably different from that in the conventional two-dimensional (2D) pseudomorphic growth case. The models are first applied to an ideal spherical and cylindrical Si 1-x Ge x particle in a large Si matrix. In contrast to the 2D case, the band alignments for both structures are predicted to be strongly type II, where the conduction-band edge and the valence-band edge of the Si matrix are both significantly lower than those in the Si 1-x Ge x inclusion, respectively. Band lineups and the lowest electron endash heavy-hole transition energies of a pseudomorphic V-groove Si 1-x Ge x quantum wire inside a large Si matrix have been calculated numerically for different size structures. The photoluminescence energies of a large Si 1-x Ge x V-groove structure on Si will be lower than those of conventional 2D strained Si 1-x Ge x for similar Ge contents. copyright 1997 The American Physical Society

  4. Touching points in the energy band structure of bilayer graphene superlattices

    International Nuclear Information System (INIS)

    Pham, C Huy; Nguyen, V Lien

    2014-01-01

    The energy band structure of the bilayer graphene superlattices with zero-averaged periodic δ-function potentials are studied within the four-band continuum model. Using the transfer matrix method, the study is mainly focused on examining the touching points between adjacent minibands. For the zero-energy touching points the dispersion relation derived shows a Dirac-like double-cone shape with the group velocity which is periodic in the potential strength P with the period of π and becomes anisotropic at relatively large P. From the finite-energy touching points we have identified those located at zero wave-number. It was shown that for these finite-energy touching points the dispersion is direction-dependent in the sense that it is linear or parabolic in the direction parallel or perpendicular to the superlattice direction, respectively. We have also calculated the density of states and the conductivity which demonstrates a manifestation of the touching points examined. (paper)

  5. Development of an automatic frequency control system for an X-band (=9300 MHz) RF electron linear accelerator

    Science.gov (United States)

    Cha, Sungsu; Kim, Yujong; Lee, Byung Cheol; Park, Hyung Dal; Lee, Seung Hyun; Buaphad, Pikad

    2017-05-01

    KAERI is developing a 6 MeV X-band radio frequency (RF) electron linear accelerator for medical purposes. The proposed X-band accelerator consists of an e-gun, an accelerating structure, two solenoid magnets, two steering magnets, a magnetron, a modulator, and an automatic frequency control (AFC) system. The accelerating structure of the component consists of oxygen-free high-conductivity copper (OFHC). Therefore, the ambient temperature changes the volume, and the resonance frequency of the accelerating structure also changes. If the RF frequency of a 9300 MHz magnetron and the resonance frequency of the accelerating structure do not match, it can degrade the performance. That is, it will decrease the output power, lower the beam current, decrease the X-ray dose rate, increase the reflection power, and result in unstable operation of the accelerator. Accelerator operation should be possible at any time during all four seasons. To prevent humans from being exposed to radiation when it is operated, the accelerator should also be operable through remote monitoring and remote control. Therefore, the AFC system is designed to meet these requirements; it is configured based on the concept of a phase-locked loop (PLL) model, which includes an RF section, an intermediate frequency (IF) [1-3] section, and a local oscillator (LO) section. Some resonance frequency controllers use a DC motor, chain, and potentiometer to store the position and tune the frequency [4,5]. Our AFC system uses a step motor to tune the RF frequency of the magnetron. The maximum tuning turn number of our magnetron frequency tuning shaft is ten. Since the RF frequency of our magnetron is 9300±25 MHz, it gives 5 MHz (∵±25 MHz/10 turns → 50 MHz/10 turns =5 MHz/turn) frequency tuning per turn. The rotation angle of our step motor is 0.72° per step and the total step number per one rotation is 360°/0.72°=500 steps. Therefore, the tuning range per step is 10 kHz/step (=5 MHz per turn/500 steps per

  6. Development of an automatic frequency control system for an X-band (=9300 MHz) RF electron linear accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Sungsu, E-mail: sscha@kaeri.re.kr [Nuclear Data Center, Korea Atomic Energy Research Institute (KAERI), Daejeon 34057 (Korea, Republic of); Kim, Yujong; Lee, Byung Cheol [Nuclear Data Center, Korea Atomic Energy Research Institute (KAERI), Daejeon 34057 (Korea, Republic of); Park, Hyung Dal [Radiation Technology eXcellence(RTX), Daejeon 34025 (Korea, Republic of); Lee, Seung Hyun [Department of Energy Science, Sungkyunkwan University(SKKU), Suwon 16419 (Korea, Republic of); Buaphad, Pikad [Nuclear Data Center, Korea Atomic Energy Research Institute (KAERI), Daejeon 34057 (Korea, Republic of); Radiation Technology eXcellence(RTX), Daejeon 34025 (Korea, Republic of); Accelerator and Nuclear Fusion Physical Engineering, University of Science and Technology(UST), Daejeon 34113 (Korea, Republic of)

    2017-05-21

    KAERI is developing a 6 MeV X-band radio frequency (RF) electron linear accelerator for medical purposes. The proposed X-band accelerator consists of an e-gun, an accelerating structure, two solenoid magnets, two steering magnets, a magnetron, a modulator, and an automatic frequency control (AFC) system. The accelerating structure of the component consists of oxygen-free high-conductivity copper (OFHC). Therefore, the ambient temperature changes the volume, and the resonance frequency of the accelerating structure also changes. If the RF frequency of a 9300 MHz magnetron and the resonance frequency of the accelerating structure do not match, it can degrade the performance. That is, it will decrease the output power, lower the beam current, decrease the X-ray dose rate, increase the reflection power, and result in unstable operation of the accelerator. Accelerator operation should be possible at any time during all four seasons. To prevent humans from being exposed to radiation when it is operated, the accelerator should also be operable through remote monitoring and remote control. Therefore, the AFC system is designed to meet these requirements; it is configured based on the concept of a phase-locked loop (PLL) model, which includes an RF section, an intermediate frequency (IF) [1-3] section, and a local oscillator (LO) section. Some resonance frequency controllers use a DC motor, chain, and potentiometer to store the position and tune the frequency [4,5]. Our AFC system uses a step motor to tune the RF frequency of the magnetron. The maximum tuning turn number of our magnetron frequency tuning shaft is ten. Since the RF frequency of our magnetron is 9300±25 MHz, it gives 5 MHz (∵±25 MHz/10 turns → 50 MHz/10 turns =5 MHz/turn) frequency tuning per turn. The rotation angle of our step motor is 0.72° per step and the total step number per one rotation is 360°/0.72°=500 steps. Therefore, the tuning range per step is 10 kHz/step (=5 MHz per turn/500 steps per

  7. Development of an automatic frequency control system for an X-band (=9300 MHz) RF electron linear accelerator

    International Nuclear Information System (INIS)

    Cha, Sungsu; Kim, Yujong; Lee, Byung Cheol; Park, Hyung Dal; Lee, Seung Hyun; Buaphad, Pikad

    2017-01-01

    KAERI is developing a 6 MeV X-band radio frequency (RF) electron linear accelerator for medical purposes. The proposed X-band accelerator consists of an e-gun, an accelerating structure, two solenoid magnets, two steering magnets, a magnetron, a modulator, and an automatic frequency control (AFC) system. The accelerating structure of the component consists of oxygen-free high-conductivity c