Evaluation of three lidar scanning strategies for turbulence measurements

DOE PAGES

Newman, Jennifer F.; Klein, Petra M.; Wharton, Sonia; ...

2016-05-03

Several errors occur when a traditional Doppler beam swinging (DBS) or velocity–azimuth display (VAD) strategy is used to measure turbulence with a lidar. To mitigate some of these errors, a scanning strategy was recently developed which employs six beam positions to independently estimate the u, v, and w velocity variances and covariances. In order to assess the ability of these different scanning techniques to measure turbulence, a Halo scanning lidar, WindCube v2 pulsed lidar, and ZephIR continuous wave lidar were deployed at field sites in Oklahoma and Colorado with collocated sonic anemometers.Results indicate that the six-beam strategy mitigates some of the errors caused bymore » VAD and DBS scans, but the strategy is strongly affected by errors in the variance measured at the different beam positions. The ZephIR and WindCube lidars overestimated horizontal variance values by over 60 % under unstable conditions as a result of variance contamination, where additional variance components contaminate the true value of the variance. A correction method was developed for the WindCube lidar that uses variance calculated from the vertical beam position to reduce variance contamination in the u and v variance components. The correction method reduced WindCube variance estimates by over 20 % at both the Oklahoma and Colorado sites under unstable conditions, when variance contamination is largest. This correction method can be easily applied to other lidars that contain a vertical beam position and is a promising method for accurately estimating turbulence with commercially available lidars.« less

Evaluation of three lidar scanning strategies for turbulence measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Newman, Jennifer F.; Klein, Petra M.; Wharton, Sonia

Several errors occur when a traditional Doppler beam swinging (DBS) or velocity–azimuth display (VAD) strategy is used to measure turbulence with a lidar. To mitigate some of these errors, a scanning strategy was recently developed which employs six beam positions to independently estimate the u, v, and w velocity variances and covariances. In order to assess the ability of these different scanning techniques to measure turbulence, a Halo scanning lidar, WindCube v2 pulsed lidar, and ZephIR continuous wave lidar were deployed at field sites in Oklahoma and Colorado with collocated sonic anemometers.Results indicate that the six-beam strategy mitigates some of the errors caused bymore » VAD and DBS scans, but the strategy is strongly affected by errors in the variance measured at the different beam positions. The ZephIR and WindCube lidars overestimated horizontal variance values by over 60 % under unstable conditions as a result of variance contamination, where additional variance components contaminate the true value of the variance. A correction method was developed for the WindCube lidar that uses variance calculated from the vertical beam position to reduce variance contamination in the u and v variance components. The correction method reduced WindCube variance estimates by over 20 % at both the Oklahoma and Colorado sites under unstable conditions, when variance contamination is largest. This correction method can be easily applied to other lidars that contain a vertical beam position and is a promising method for accurately estimating turbulence with commercially available lidars.« less

Trajectory measurements and correlations in the final focus beam line at the KEK Accelerator Test Facility

NASA Astrophysics Data System (ADS)

Renier, Y.; Bambade, P.; Tauchi, T.; White, G. R.; Boogert, S.

2013-06-01

The Accelerator Test Facility 2 (ATF2) commissioning group aims to demonstrate the feasibility of the beam delivery system of the next linear colliders (ILC and CLIC) as well as to define and to test the tuning methods. As the design vertical beam sizes of the linear colliders are about few nanometers, the stability of the trajectory as well as the control of the aberrations are very critical. ATF2 commissioning started in December 2008, and thanks to submicron resolution beam position monitors (BPMs), it has been possible to measure the beam position fluctuation along the final focus of ATF2 during the 2009 runs. The optics was not the nominal one yet, with a lower focusing to make the tuning easier. In this paper, a method to measure the noise of each BPM every pulse, in a model-independent way, will be presented. A method to reconstruct the trajectory’s fluctuations is developed which uses the previously determined BPM resolution. As this reconstruction provides a measurement of the beam energy fluctuations, it was also possible to measure the horizontal and vertical dispersion function at each BPMs parasitically. The spatial and angular dispersions can be fitted from these measurements with uncertainties comparable with usual measurements.

Observation of electron cloud instabilities and emittance dilution at the Cornell electron-positron Storage ring Test Accelerator

DOE PAGES

Holtzapple, R. L.; Billing, M. G.; Campbell, R. C.; ...

2016-04-11

Electron cloud related emittance dilution and instabilities of bunch trains limit the performance of high intensity circular colliders. One of the key goals of the Cornell electron-positron storage ring Test Accelerator (CesrTA) research program is to improve our understanding of how the electron cloud alters the dynamics of bunches within the train. Single bunch beam diagnostics have been developed to measure the beam spectra, vertical beam size, two important dynamical effects of beams interacting with the electron cloud, for bunch trains on a turn-by-turn basis. Experiments have been performed at CesrTA to probe the interaction of the electron cloud withmore » stored positron bunch trains. The purpose of these experiments was to characterize the dependence of beam-electron cloud interactions on the machine parameters such as bunch spacing, vertical chromaticity, and bunch current. The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 1) a gated beam position monitor (BPM) and spectrum analyzer to measure the bunch-by-bunch frequency spectrum of the bunch trains, 2) an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. In this study we report on the observations from these experiments and analyze the effects of the electron cloud on the stability of bunches in a train under many different operational conditions.« less

Observation of Electron Cloud Instabilities and Emittance Dilution at the Cornell Electron-Positron Storage Ring Test Accelerator

NASA Astrophysics Data System (ADS)

Holtzapple, R. L.; Billing, M. G.; Campbell, R. C.; Dugan, G. F.; Flanagan, J.; McArdle, K. E.; Miller, M. I.; Palmer, M. A.; Ramirez, G. A.; Sonnad, K. G.; Totten, M. M.; Tucker, S. L.; Williams, H. A.

2016-04-01

Electron cloud related emittance dilution and instabilities of bunch trains limit the performance of high intensity circular colliders. One of the key goals of the Cornell electron-positron storage ring Test Accelerator (CesrTA) research program is to improve our understanding of how the electron cloud alters the dynamics of bunches within the train. Single bunch beam diagnotics have been developed to measure the beam spectra, vertical beam size, two important dynamical effects of beams interacting with the electron cloud, for bunch trains on a turn-by-turn basis. Experiments have been performed at CesrTA to probe the interaction of the electron cloud with stored positron bunch trains. The purpose of these experiments was to characterize the dependence of beam-electron cloud interactions on the machine parameters such as bunch spacing, vertical chromaticity, and bunch current. The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 1) a gated beam position monitor (BPM) and spectrum analyzer to measure the bunch-by-bunch frequency spectrum of the bunch trains; 2) an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. In this paper we report on the observations from these experiments and analyze the effects of the electron cloud on the stability of bunches in a train under many different operational conditions.

Photon beam position monitor

DOEpatents

Kuzay, T.M.; Shu, D.

1995-02-07

A photon beam position monitor is disclosed for use in the front end of a beamline of a high heat flux and high energy photon source such as a synchrotron radiation storage ring detects and measures the position and, when a pair of such monitors are used in tandem, the slope of a photon beam emanating from an insertion device such as a wiggler or an undulator inserted in the straight sections of the ring. The photon beam position monitor includes a plurality of spaced blades for precisely locating the photon beam, with each blade comprised of chemical vapor deposition (CVD) diamond with an outer metal coating of a photon sensitive metal such as tungsten, molybdenum, etc., which combination emits electrons when a high energy photon beam is incident upon the blade. Two such monitors are contemplated for use in the front end of the beamline, with the two monitors having vertically and horizontally offset detector blades to avoid blade ''shadowing''. Provision is made for aligning the detector blades with the photon beam and limiting detector blade temperature during operation. 18 figs.

VERTICAL BEAM SIZE CONTROL IN TLS AND TPS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

KUO, C.C.; CHEN, J.R.; CHOU, P.J.

2006-06-26

Vertical beam size control is an important issue in the light source operations. The horizontal-vertical betatron coupling and vertical dispersion were measured and corrected to small values in the TLS 1.5 GeV storage ring. Estimated beam sizes are compared with the measured values. By employing an effective transverse damping system, the vertical beam blow-up due to transverse coherent instabilities, such as the fast-ion beam instability, was suppressed. As a result, the light source is very stable. In NSRRC we are designing an ultra low emittance 3-GeV storage ring and its designed vertical beam size could be as small as amore » few microns. The ground and mechanic vibration effects, and coherent instabilities could spoil the expected photon brightness due to blow-up of the vertical beam size if not well taken care of. The contributions of these effects to vertical beam size increase will be evaluated and the counter measures to minimize them will be proposed and reported in this paper.« less

Formation of a uniform ion beam using octupole magnets for BioLEIR facility at CERN

NASA Astrophysics Data System (ADS)

Amin, T.; Barlow, R.; Ghithan, S.; Roy, G.; Schuh, S.

2018-04-01

The possibility to transform the Low Energy Ion Ring (LEIR) accelerator at CERN into a multidisciplinary, biomedical research facility (BioLEIR) was investigated based on a request from the biomedical community. BioLEIR aims to provide a unique facility with a range of fully stripped ion beams (e.g. He, Li, Be, B, C, N, O) and energies suitable for multidisciplinary biomedical, clinically-oriented research. Two horizontal and one vertical beam transport lines have been designed for transporting the extracted beam from LEIR to three experimental end-stations. The vertical beamline was designed for a maximum energy of 75 MeV/u, while the two horizontal beamlines shall deliver up to a maximum energy of 440 MeV/u. A pencil beam of 4.3 mm FWHM (Full Width Half Maximum) as well as a homogeneous broad beam of 40 × 40 mm2, with a beam homogeneity better than ±4%, are available at the first horizontal (H1) irradiation point, while only a pencil beam is available at the second horizontal (H2) and vertical (V) irradiation points. The H1 irradiation point shall be used to conduct systematic studies of the radiation effect from different ion species on cell-lines. The H1 beamline was designed to utilize two octupole magnets which transform the Gaussian beam distribution at the target location into an approximately uniformly distributed rectangular beam. In this paper, we report on the multi-particle tracking calculations performed using MAD-X software suite for the H1 beam optics to arrive at a homogeneous broad beam on target using nonlinear focusing techniques, and on those to create a Gaussian pencil beam on target by adjusting quadrupoles strengths and positions.

Beam Stability R&D for the APS MBA Upgrade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sereno, Nicholas S.; Arnold, Ned D.; Bui, Hanh D.

2015-01-01

Beam diagnostics required for the APS Multi-bend acromat (MBA) are driven by ambitious beam stability requirements. The major AC stability challenge is to correct rms beam motion to 10% the rms beam size at the insertion device source points from0.01 to 1000 Hz. The vertical plane represents the biggest challenge forAC stability, which is required to be 400 nm rms for a 4-micron vertical beam size. In addition to AC stability, long-term drift over a period of seven days is required to be 1 micron or less. Major diagnostics R&D components include improved rf beam position processing using commercially availablemore » FPGA-based BPM processors, new X-ray beam position monitors based on hard X-ray fluorescence from copper and Compton scattering off diamond, mechanical motion sensing to detect and correct long-term vacuum chamber drift, a new feedback system featuring a tenfold increase in sampling rate, and a several-fold increase in the number of fast correctors and BPMs in the feedback algorithm. Feedback system development represents a major effort, and we are pursuing development of a novel algorithm that integrates orbit correction for both slow and fast correctors down to DC simultaneously. Finally, a new data acquisition system (DAQ) is being developed to simultaneously acquire streaming data from all diagnostics as well as the feedback processors for commissioning and fault diagnosis. Results of studies and the design effort are reported.« less

High yield of self-catalyzed GaAs nanowire arrays grown on silicon via gallium droplet positioning.

PubMed

Plissard, S; Larrieu, G; Wallart, X; Caroff, P

2011-07-08

We report and detail a method to achieve growth of vertical self-catalyzed GaAs nanowires directly on Si(111) with a near-perfect vertical yield, using electron-beam-defined arrays of holes in a dielectric layer and molecular beam epitaxy. In our conditions, GaAs nanowires are grown along a vapor-liquid-solid mechanism, using in situ self-forming Ga droplets. The focus of this paper is to understand the role of the substrate preparation and of the pre-growth conditioning. Without changing temperature or the V/III ratio, the yield of vertical nanowires is increased incrementally up to 95%. The possibility to achieve very dense arrays, with center-to-center inter-wire distances less than 100 nm, is demonstrated.

Optical levitation of a non-spherical particle in a loosely focused Gaussian beam.

PubMed

Chang, Cheong Bong; Huang, Wei-Xi; Lee, Kyung Heon; Sung, Hyung Jin

2012-10-08

The optical force on a non-spherical particle subjected to a loosely focused laser beam was calculated using the dynamic ray tracing method. Ellipsoidal particles with different aspect ratios, inclination angles, and positions were modeled, and the effects of these parameters on the optical force were examined. The vertical component of the optical force parallel to the laser beam axis decreased as the aspect ratio decreased, whereas the ellipsoid with a small aspect ratio and a large inclination angle experienced a large vertical optical force. The ellipsoids were pulled toward or repelled away from the laser beam axis, depending on the inclination angle, and they experienced a torque near the focal point. The behavior of the ellipsoids in a viscous fluid was examined by analyzing a dynamic simulation based on the penalty immersed boundary method. As the ellipsoids levitated along the direction of the laser beam propagation, they moved horizontally with rotation. Except for the ellipsoid with a small aspect ratio and a zero inclination angle near the focal point, the ellipsoids rotated until the major axis aligned with the laser beam axis.

The parameters effect on the structural performance of damaged steel box beam using Taguchi method

NASA Astrophysics Data System (ADS)

El-taly, Boshra A.; Abd El Hameed, Mohamed F.

2018-03-01

In the current study, the influence of notch or opening parameters and the positions of the applied load on the structural performance of steel box beams up to failure was investigated using Finite Element analysis program, ANSYS. The Taguchi-based design of experiments technique was used to plan the current study. The plan included 12 box steel beams; three intact beams, and nine damaged beams (with opening) in the beams web. The numerical studies were conducted under varying the spacing between the two concentrated point loads (location of applied loads), the notch (opening) position, and the ratio between depth and width of the notch with a constant notch area. According to Taguchi analysis, factor X (location of the applied loads) was found the highest contributing parameters for the variation of the ultimate load, vertical deformation, shear stresses, and the compressive normal stresses.

Fast global orbit feedback system in PLS-II

NASA Astrophysics Data System (ADS)

Lee, J.; Kim, C.; Kim, J. M.; Kim, K. R.; Lee, E. H.; Lee, J. W.; Lee, T. Y.; Park, C. D.; Shin, S.; Yoon, J. C.; Cho, W. S.; Park, G. S.; Kim, S. C.

2016-12-01

The transverse position of the electron beam in the Pohang Light Source-II is stabilized by the global orbit feedback system. A slow orbit feedback system has been operating at 2 Hz, and a fast orbit feedback (FOFB) system at 813 Hz was installed recently. This FOFB system consists of 96 electron-beam-position monitors, 48 horizontal fast correctors, 48 vertical fast correctors and Versa Module Europa bus control system. We present the design and implementation of the FOFB system and its test result. Simulation analysis is presented and future improvements are suggested.

Mini-beam collimator enables microcrystallography experiments on standard beamlines

PubMed Central

Fischetti, Robert F.; Xu, Shenglan; Yoder, Derek W.; Becker, Michael; Nagarajan, Venugopalan; Sanishvili, Ruslan; Hilgart, Mark C.; Stepanov, Sergey; Makarov, Oleg; Smith, Janet L.

2009-01-01

The high-brilliance X-ray beams from undulator sources at third-generation synchrotron facilities are excellent tools for solving crystal structures of important and challenging biological macromolecules and complexes. However, many of the most important structural targets yield crystals that are too small or too inhomogeneous for a ‘standard’ beam from an undulator source, ∼25–50 µm (FWHM) in the vertical and 50–100 µm in the horizontal direction. Although many synchrotron facilities have microfocus beamlines for other applications, this capability for macromolecular crystallography was pioneered at ID-13 of the ESRF. The National Institute of General Medical Sciences and National Cancer Institute Collaborative Access Team (GM/CA-CAT) dual canted undulator beamlines at the APS deliver high-intensity focused beams with a minimum focal size of 20 µm × 65 µm at the sample position. To meet growing user demand for beams to study samples of 10 µm or less, a ‘mini-beam’ apparatus was developed that conditions the focused beam to either 5 µm or 10 µm (FWHM) diameter with high intensity. The mini-beam has a symmetric Gaussian shape in both the horizontal and vertical directions, and reduces the vertical divergence of the focused beam by 25%. Significant reduction in background was achieved by implementation of both forward- and back-scatter guards. A unique triple-collimator apparatus, which has been in routine use on both undulator beamlines since February 2008, allows users to rapidly interchange the focused beam and conditioned mini-beams of two sizes with a single mouse click. The device and the beam are stable over many hours of routine operation. The rapid-exchange capability has greatly facilitated sample screening and resulted in several structures that could not have been obtained with the larger focused beam. PMID:19240333

Submacropulse electron-beam dynamics correlated with higher-order modes in Tesla-type superconducting rf cavities

NASA Astrophysics Data System (ADS)

Lumpkin, A. H.; Thurman-Keup, R.; Edstrom, D.; Ruan, J.; Eddy, N.; Prieto, P.; Napoly, O.; Carlsten, B. E.; Bishofberger, K.

2018-06-01

We report the direct observations of submacropulse beam centroid oscillations correlated with higher order modes (HOMs) which were generated by off-axis electron beam steering in TESLA-type superconducting rf cavities. The experiments were performed at the Fermilab Accelerator Science and Technology (FAST) facility using its unique configuration of a photocathode rf gun injecting beam into two separated nine-cell cavities in series with corrector magnets and beam position monitors (BPMs) located before, between, and after them. Oscillations of ˜100 kHz in the vertical plane and ˜380 kHz in the horizontal plane with up to 600 -μ m amplitudes were observed in a 3-MHz micropulse repetition rate beam with charges of 100, 300, 500, and 1000 pC /b . However, the effects were much reduced at 100 pC /b . The measurements were based on HOM detector circuitry targeting the first and second dipole passbands, rf BPM bunch-by-bunch array data, imaging cameras, and a framing camera. Calculations reproduced the oscillation frequencies of the phenomena in the vertical case. In principle, these fundamental results may be scaled to cryomodule configurations of major accelerator facilities.

Submacropulse electron-beam dynamics correlated with higher-order modes in Tesla-type superconducting rf cavities

DOE PAGES

Lumpkin, A. H.; Thurman-Keup, R.; Edstrom, D.; ...

2018-06-04

Here, we report the direct observations of submacropulse beam centroid oscillations correlated with higher order modes (HOMs) which were generated by off-axis electron beam steering in TESLA-type superconducting rf cavities. The experiments were performed at the Fermilab Accelerator Science and Technology (FAST) facility using its unique configuration of a photocathode rf gun injecting beam into two separated nine-cell cavities in series with corrector magnets and beam position monitors (BPMs) located before, between, and after them. Oscillations of ~100 kHz in the vertical plane and ~380 kHz in the horizontal plane with up to 600-μm amplitudes were observed in a 3-MHzmore » micropulse repetition rate beam with charges of 100, 300, 500, and 1000 pC/b. However, the effects were much reduced at 100 pC/b. The measurements were based on HOM detector circuitry targeting the first and second dipole passbands, rf BPM bunch-by-bunch array data, imaging cameras, and a framing camera. Calculations reproduced the oscillation frequencies of the phenomena in the vertical case. In principle, these fundamental results may be scaled to cryomodule configurations of major accelerator facilities.« less

Experimental Test of Data Analysis Methods from Staggered Pair X-ray Beam Position Monitors at Bending Magnet Beamlines

NASA Astrophysics Data System (ADS)

Buth, G.; Huttel, E.; Mangold, S.; Steininger, R.; Batchelor, D.; Doyle, S.; Simon, R.

2013-03-01

Different methods have been proposed to calculate the vertical position of the photon beam centroid from the four blade currents of staggered pair X-ray beam position monitors (XBPMs) at bending magnet beamlines since they emerged about 15 years ago. The original difference-over-sum method introduced by Peatman and Holldack is still widely used, even though it has been proven to be rather inaccurate at large beam displacements. By systematically generating bumps in the electron orbit of the ANKA storage ring and comparing synchronized data from electron BPMs and XBPM blade currents, we have been able to show that the log-ratio method by S. F. Lin, B.G. Sun et al. is superior (meaning the characteristic being closer to linear) to the ratio method, which in turn is superior to the difference over sum method. These findings are supported by simulations of the XBPM response to changes of the beam centroid. The heuristic basis for each of the methods is investigated. The implications on using XBPM readings for orbit correction are discussed

Long range laser traversing system

NASA Technical Reports Server (NTRS)

Caudill, L. O. (Inventor)

1974-01-01

The relative azimuth bearing between first and second spaced terrestrial points which may be obscured from each other by intervening terrain is measured by placing at one of the points a laser source for projecting a collimated beam upwardly in the vertical plane. The collimated laser beam is detected at the second point by positioning the optical axis of a receiving instrument for the laser beam in such a manner that the beam intercepts the optical axis. In response to the optical axis intercepting the beam, the beam is deflected into two different ray paths by a beam splitter having an apex located on the optical axis. The energy in the ray paths is detected by separate photoresponsive elements that drive logic networks for proving indications of: (1) the optical axis intercepting the beam; (2) the beam being on the left of the optical axis and (3) the beam being on the right side of the optical axis.

Fabrication of precision high quality facets on molecular beam epitaxy material

DOEpatents

Petersen, Holly E.; Goward, William D.; Dijaili, Sol P.

2001-01-01

Fabricating mirrored vertical surfaces on semiconductor layered material grown by molecular beam epitaxy (MBE). Low energy chemically assisted ion beam etching (CAIBE) is employed to prepare mirrored vertical surfaces on MBE-grown III-V materials under unusually low concentrations of oxygen in evacuated etching atmospheres of chlorine and xenon ion beams. UV-stabilized smooth-surfaced photoresist materials contribute to highly vertical, high quality mirrored surfaces during the etching.

PBF Reactor Building (PER620). Camera faces south toward verticallift door, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

PBF Reactor Building (PER-620). Camera faces south toward vertical-lift door, which is closed. Note crane and its trolley positioned near door; its rails along side walls. Reactor vessel and lifting beams are positioned above reactor pit. Photographer: John Capek. Date: January 9, 1970. INEEL negative no. 70-132 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

Beam based alignment and its relevance in Indus-2.

PubMed

Jena, Saroj Kumar; Husain, Riyasat; Gandhi, M L; Agrawal, R K; Yadav, S; Ghodke, A D

2015-09-01

Initially in the Indus-2 storage ring, the closed orbit distortion (COD) could be best corrected to 1.3 mm rms in the horizontal and 0.43 mm rms in the vertical plane. The strength of the corrector magnets required high values for COD correction. This revealed that offsets in COD readout by the beam position monitors (BPMs) played a role in not achieving a rms COD lower than the above value. Thus, the offset between the electrical center of BPMs and the magnetic center of the nearest quadrupole magnet could be estimated using the beam based alignment (BBA) method. It prefers that the quadrupole magnet is able to be controlled individually and active shunt power supply (ASPS) system was designed for this purpose that works efficiently. This paper describes the methodology of BBA, topology of ASPS and its performance, and COD minimization using the measured BPM offsets. After BBA, the COD could be reduced to 0.45 mm rms and 0.2 mm rms in horizontal and vertical planes, respectively.

Beam based alignment and its relevance in Indus-2

NASA Astrophysics Data System (ADS)

Jena, Saroj Kumar; Husain, Riyasat; Gandhi, M. L.; Agrawal, R. K.; Yadav, S.; Ghodke, A. D.

2015-09-01

Initially in the Indus-2 storage ring, the closed orbit distortion (COD) could be best corrected to 1.3 mm rms in the horizontal and 0.43 mm rms in the vertical plane. The strength of the corrector magnets required high values for COD correction. This revealed that offsets in COD readout by the beam position monitors (BPMs) played a role in not achieving a rms COD lower than the above value. Thus, the offset between the electrical center of BPMs and the magnetic center of the nearest quadrupole magnet could be estimated using the beam based alignment (BBA) method. It prefers that the quadrupole magnet is able to be controlled individually and active shunt power supply (ASPS) system was designed for this purpose that works efficiently. This paper describes the methodology of BBA, topology of ASPS and its performance, and COD minimization using the measured BPM offsets. After BBA, the COD could be reduced to 0.45 mm rms and 0.2 mm rms in horizontal and vertical planes, respectively.

New Beam Scanning Device for Active Beam Delivery System (BDS) in Proton Therapy

NASA Astrophysics Data System (ADS)

Variale, V.; Mastromarco, M.; Colamaria, F.; Colella, D.

A new Beam Delivery System (BDS) has been studied in the framework of a new proton therapy project, called AMIDERHA. It is characterized by an active scanning system for target irradiation with a pencil beam. The project is based on the use of a Linac with variable final energy and the Robotized Patient Positioning System instead of the traditional gantry. As a consequence, in the active BDS of AMIDERHA a pencil beam scanning system with a relatively long Source to Axis Distance (SAD) can be used. In this contribution, the idea of using a unique new device capable of both horizontal and vertical beam scansion for the AMIDERHA active BDS will be presented and discussed. Furthermore, a preliminary design of that device will be shown, together with the results of simulations.

High intensity proton injector for facility of antiproton and ion research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berezov, R., E-mail: r.berezov@gsi.de; Brodhage, R.; Fils, J.

The high current ion source with the low energy beam transport (LEBT) will serve as injector into the proton LINAC to provide primary proton beam for the production of antiprotons. The pulsed ion source developed and built in CEA/Saclay operates with a frequency of 2.45 GHz based on ECR plasma production with two coils with 87.5 mT magnetic field necessary for the electron cyclotron resonance. The compact LEBT consists of two solenoids with a maximum magnetic field of 500 mT including two integrated magnetic steerers to adjust the horizontal and vertical beam positions. The total length of the compact LEBTmore » is 2.3 m and was made as short as possible to reduced emittance growth along the beam line. To measure ion beam intensity behind the pentode extraction system, between solenoids and at the end of the beam line, two current transformers and a Faraday cup are installed. To get information about the beam quality and position, the diagnostic chamber with different equipment will be installed between the two solenoids. This article reports the current status of the proton injector for the facility of antiproton and ion research.« less

Anti-terrorist vehicle crash impact energy absorbing barrier

DOEpatents

Swahlan, David J.

1989-01-01

An anti-terrorist vehicle crash barrier includes side support structures, crushable energy absorbing aluminum honeycomb modules, and an elongated impact-resistant beam extending between, and at its opposite ends through vertical guideways defined by, the side support structures. An actuating mechanism supports the beam at its opposite ends for movement between a lowered barrier-withdrawn position in which a traffic-supporting side of the beam is aligned with a traffic-bearing surface permitting vehicular traffic between the side support structures and over the beam, and a raised barrier-imposed position in which the beam is aligned with horizontal guideways defined in the side support structures above the traffic-bearing surface, providing an obstruction to vehicular traffic between the side support structures. The beam is movable rearwardly in the horizontal guideways with its opposite ends disposed transversely therethrough upon being impacted at its forward side by an incoming vehicle. The crushable modules are replaceably disposed in the horizontal guideways between aft ends thereof and the beam. The beam, replaceable modules, side support structures and actuating mechanism are separate and detached from one another such that the beam and replaceable modules are capable of coacting to disable and stop an incoming vehicle without causing structural damage to the side support structures and actuating mechanism.

Creation of vector beams from a polarization diffraction grating using a programmable liquid crystal spatial light modulator and a q-plate

NASA Astrophysics Data System (ADS)

Badham, Katherine Emily

This thesis presents the ability of complete polarization control of light to create a polarization diffraction grating (PDG). This system has the ability to create diffracted light with each order having a separate high-order polarization state in one location on the optical axis. First, an external Excel program is used to create a grating phase profile from userspecified target diffraction orders. High-order vector beams in this PDG are created using a combination of two devices---a liquid crystal spatial light modulator (LC-SLM) manufactured by Seiko Epson, and a tunable q -plate from Citizen Holdings Co. The transmissive SLM is positioned in an optical setup with a reflective architecture allowing control over both the horizontal and vertical components of the laser beam. The SLM has its LC director oriented vertically only affecting the vertically polarized state, however, the optical setup allows modulation of both vertical and horizontal components by the use of a quarter-wave plate (QWP) and a mirror to rotate the polarizations 90 degrees. Each half of the SLM is encoded with an anisotropic phase-only diffraction grating which are superimposed to create a select number of orders with the desired polarization states and equally distributed intensity. The technique of polarimetry is used to confirm the polarization state of each diffraction order. The q-plate is an inhomogeneous birefringent waveplate which has the ability to convert zero-order vector beams into first-order vector beams. The physical placement of this device into the system converts the orders with zero-order polarization states to first-order polarization states. The light vector patterns of each diffraction order confirm which first-order polarization state of is produced. A specially made PDG sextuplicator is encoded onto the SLM to generate six diffraction orders with separate states of polarization.

SPICE-NIRS Microbeam: a focused vertical system for proton irradiation of a single cell for radiobiological research

PubMed Central

Konishi, Teruaki; Oikawa, Masakazu; Suya, Noriyoshi; Ishikawa, Takahiro; Maeda, Takeshi; Kobayashi, Alisa; Shiomi, Naoko; Kodama, Kumiko; Hamano, Tsuyoshi; Homma-Takeda, Shino; Isono, Mayu; Hieda, Kotaro; Uchihori, Yukio; Shirakawa, Yoshiyuki

2013-01-01

The Single Particle Irradiation system to Cell (SPICE) facility at the National Institute of Radiological Sciences (NIRS) is a focused vertical microbeam system designed to irradiate the nuclei of adhesive mammalian cells with a defined number of 3.4 MeV protons. The approximately 2-μm diameter proton beam is focused with a magnetic quadrupole triplet lens and traverses the cells contained in dishes from bottom to top. All procedures for irradiation, such as cell image capturing, cell recognition and position calculation, are automated. The most distinctive characteristic of the system is its stability and high throughput; i.e. 3000 cells in a 5 mm × 5 mm area in a single dish can be routinely irradiated by the 2-μm beam within 15 min (the maximum irradiation speed is 400 cells/min). The number of protons can be set as low as one, at a precision measured by CR-39 detectors to be 99.0%. A variety of targeting modes such as fractional population targeting mode, multi-position targeting mode for nucleus irradiation and cytoplasm targeting mode are available. As an example of multi-position targeting irradiation of mammalian cells, five fluorescent spots in a cell nucleus were demonstrated using the γ-H2AX immune-staining technique. The SPICE performance modes described in this paper are in routine use. SPICE is a joint-use research facility of NIRS and its beam times are distributed for collaborative research. PMID:23287773

A method for simultaneous linear optics and coupling correction for storage rings with turn-by-turn beam position monitor data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xi; Huang, Xiaobiao

2016-05-13

Here, we propose a method to simultaneously correct linear optics errors and linear coupling for storage rings using turn-by-turn (TbT) beam position monitor (BPM) data. The independent component analysis (ICA) method is used to isolate the betatron normal modes from the measured TbT BPM data. The betatron amplitudes and phase advances of the projections of the normal modes on the horizontal and vertical planes are then extracted, which, combined with dispersion measurement, are used to fit the lattice model. The fitting results are used for lattice correction. Finally, the method has been successfully demonstrated on the NSLS-II storage ring.

A method for simultaneous linear optics and coupling correction for storage rings with turn-by-turn beam position monitor data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xi; Huang, Xiaobiao

2016-08-01

We propose a method to simultaneously correct linear optics errors and linear coupling for storage rings using turn-by-turn (TbT) beam position monitor (BPM) data. The independent component analysis (ICA) method is used to isolate the betatron normal modes from the measured TbT BPM data. The betatron amplitudes and phase advances of the projections of the normal modes on the horizontal and vertical planes are then extracted, which, combined with dispersion measurement, are used to fit the lattice model. Furthermore, the fitting results are used for lattice correction. Our method has been successfully demonstrated on the NSLS-II storage ring.

A method for simultaneous linear optics and coupling correction for storage rings with turn-by-turn beam position monitor data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xi; Huang, Xiaobiao

2016-08-01

We propose a method to simultaneously correct linear optics errors and linear coupling for storage rings using turn-by-turn (TbT) beam position monitor (BPM) data. The independent component analysis (ICA) method is used to isolate the betatron normal modes from the measured TbT BPM data. The betatron amplitudes and phase advances of the projections of the normal modes on the horizontal and vertical planes are then extracted, which, combined with dispersion measurement, are used to fit the lattice model. The fitting results are used for lattice correction. The method has been successfully demonstrated on the NSLS-II storage ring.

Deflection-Compensating Beam for use inside a Cylinder

NASA Technical Reports Server (NTRS)

Goodman, Dwight; Myers, Neill; Herren, Kenneth

2008-01-01

A design concept for a beam for a specific application permits variations and options for satisfying competing requirements to minimize certain deflections under load and to minimize the weight of the beam. In the specific application, the beam is required to serve as a motion-controlled structure for supporting a mirror for optical testing in the lower third portion of a horizontal, cylindrical vacuum chamber. The cylindrical shape of the chamber is fortuitous in that it can be (and is) utilized as an essential element of the deflection-minimizing design concept. The beam is, more precisely, a table-like structure comprising a nominally flat, horizontal portion with vertical legs at its ends. The weights of the beam and whatever components it supports are reacted by the contact forces between the lower ends of the legs and the inner cylindrical chamber wall. Whereas the bending moments arising from the weights contribute to a beam deflection that is concave with its lowest point at midlength, the bending moments generated by the contact forces acting on the legs contribute to a beam deflection that is convex with its highest point at midlength. In addition, the bending of the legs in response to the weights causes the lower ends of the legs to slide downward on the cylindrical wall. By taking the standard beam-deflection equations, combining them with the geometric relationships among the legs and the horizontal portion of the beam, and treating the sliding as a component of deflection, it is possible to write an equation for the net vertical deflection as a function of the load and of position along the beam. A summary of major conclusions drawn from the equation characterization is included.

Beam steering via resonance detuning in coherently coupled vertical cavity laser arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Matthew T., E-mail: matthew.johnson.9@us.af.mil; Siriani, Dominic F.; Peun Tan, Meng

2013-11-11

Coherently coupled vertical-cavity surface-emitting laser arrays offer unique advantages for nonmechanical beam steering applications. We have applied dynamic coupled mode theory to show that the observed temporal phase shift between vertical-cavity surface-emitting array elements is caused by the detuning of their resonant wavelengths. Hence, a complete theoretical connection between the differential current injection into array elements and the beam steering direction has been established. It is found to be a fundamentally unique beam-steering mechanism with distinct advantages in efficiency, compactness, speed, and phase-sensitivity to current.

Extreme-UV scanning wafer and reticle stages

DOEpatents

Williams, Mark E.

2002-01-01

A stage for precise positioning of a chuck in three orthogonal linear axes and in three orthogonal rotation axes that includes first and second subassemblies. The a first subassembly includes (i) a monolithic mirror that supports the chuck wherein the monolithic mirror has at least two polished orthogonal faces for interferometric determination of the X, Y, and .THETA.z positions; (ii) a plurality of electromagnetic actuators that control fine positioning in all six axes and coarse positioning in one axis; (iii) a position sensor for measuring the vertical Z position of the monolithic mirror; and (iv) a Lorentz actuator, that includes magnet array, for effecting motion in the Y axis. The a second subassembly comprising a stepping axis beam over which the first subassembly is suspended, wherein the stepping axis beam includes a drive coil array for the Lorentz actuator. T the stage can also include a cable stage subassembly that is positioned a fixed distance away from the monolithic mirror and/or a mechanical zero reference for the first subassembly.

The influence of air-filled structures on wave propagation and beam formation of a pygmy sperm whale (Kogia breviceps) in horizontal and vertical planes.

PubMed

Song, Zhongchang; Zhang, Yu; Thornton, Steven W; Li, Songhai; Dong, Jianchen

2017-10-01

The wave propagation, sound field, and transmission beam pattern of a pygmy sperm whale (Kogia breviceps) were investigated in both the horizontal and vertical planes. Results suggested that the signals obtained at both planes were similarly characterized with a high peak frequency and a relatively narrow bandwidth, close to the ones recorded from live animals. The sound beam measured outside the head in the vertical plane was narrower than that of the horizontal one. Cases with different combinations of air-filled structures in both planes were used to study the respective roles in controlling wave propagation and beam formation. The wave propagations and beam patterns in the horizontal and vertical planes elucidated the important reflection effect of the spermaceti and vocal chambers on sound waves, which was highly significant in forming intensive forward sound beams. The air-filled structures, the forehead soft tissues and skull structures formed wave guides in these two planes for emitted sounds to propagate forward.

Numerical analysis of the beam position monitor pickup for the Iranian light source facility

NASA Astrophysics Data System (ADS)

Shafiee, M.; Feghhi, S. A. H.; Rahighi, J.

2017-03-01

In this paper, we describe the design of a button type Beam Position Monitor (BPM) for the low emittance storage ring of the Iranian Light Source Facility (ILSF). First, we calculate sensitivities, induced power and intrinsic resolution based on solving Laplace equation numerically by finite element method (FEM), in order to find the potential at each point of BPM's electrode surface. After the optimization of the designed BPM, trapped high order modes (HOM), wakefield and thermal loss effects are calculated. Finally, after fabrication of BPM, it is experimentally tested by using a test-stand. The results depict that the designed BPM has a linear response in the area of 2×4 mm2 inside the beam pipe and the sensitivity of 0.080 and 0.087 mm-1 in horizontal and vertical directions. Experimental results also depict that they are in a good agreement with numerical analysis.

Status of the ATF Damping Ring BPM Upgrade Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Briegel, C.; /Fermilab; Eddy, N.

2011-12-01

A substantial upgrade of the beam position monitors (BPM) at the ATF (Accelerator Test Facility) damping ring is currently in progress. Implementing digital read-out signal processing techniques in line with an optimized, low-noise analog downconverter, a resolution well below 1 mum could be demonstrated at 20 (of 96) upgraded BPM stations. The narrowband, high resolution BPM mode permits investigation of all types of non-linearities, imperfections and other obstacles in the machine which may limit the very low target aimed vertical beam emittance of < 2 pm. The technical status of the project, first beam measurements and an outlook to it'smore » finalization are presented.« less

Beam based alignment and its relevance in Indus-2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jena, Saroj Kumar; Husain, Riyasat; Gandhi, M. L.

2015-09-15

Initially in the Indus-2 storage ring, the closed orbit distortion (COD) could be best corrected to 1.3 mm rms in the horizontal and 0.43 mm rms in the vertical plane. The strength of the corrector magnets required high values for COD correction. This revealed that offsets in COD readout by the beam position monitors (BPMs) played a role in not achieving a rms COD lower than the above value. Thus, the offset between the electrical center of BPMs and the magnetic center of the nearest quadrupole magnet could be estimated using the beam based alignment (BBA) method. It prefers thatmore » the quadrupole magnet is able to be controlled individually and active shunt power supply (ASPS) system was designed for this purpose that works efficiently. This paper describes the methodology of BBA, topology of ASPS and its performance, and COD minimization using the measured BPM offsets. After BBA, the COD could be reduced to 0.45 mm rms and 0.2 mm rms in horizontal and vertical planes, respectively.« less

Evaluation of the relationship between mandibular third molar and mandibular canal by different algorithms of cone-beam computed tomography.

PubMed

Mehdizadeh, Mojdeh; Ahmadi, Navid; Jamshidi, Mahsa

2014-11-01

Exact location of the inferior alveolar nerve (IAN) bundle is very important. The aim of this study is to evaluate the relationship between the mandibular third molar and the mandibular canal by cone-beam computed tomography. This was a cross-sectional study with convenience sampling. 94 mandibular CBCTs performed with CSANEX 3D machine (Soredex, Finland) and 3D system chosen. Vertical and horizontal relationship between the mandibular canal and the third molar depicted by 3D, panoramic reformat view of CBCT and cross-sectional view. Cross-sectional view was our gold standard and other view evaluated by it. There were significant differences between the vertical and horizontal relation of nerve and tooth in all views (p < 0.001). The results showed differences in the position of the inferior alveolar nerve with different views of CBCT, so CBCT images are not quite reliable and have possibility of error.

Flow tilt angles near forest edges - Part 2: Lidar anemometry

NASA Astrophysics Data System (ADS)

Dellwik, E.; Mann, J.; Bingöl, F.

2010-05-01

A novel way of estimating near-surface mean flow tilt angles from ground based Doppler lidar measurements is presented. The results are compared with traditional mast based in-situ sonic anemometry. The tilt angle assessed with the lidar is based on 10 or 30 min mean values of the velocity field from a conically scanning lidar. In this mode of measurement, the lidar beam is rotated in a circle by a prism with a fixed angle to the vertical at varying focus distances. By fitting a trigonometric function to the scans, the mean vertical velocity can be estimated. Lidar measurements from (1) a fetch-limited beech forest site taken at 48-175 m a.g.l. (above ground level), (2) a reference site in flat agricultural terrain and (3) a second reference site in complex terrain are presented. The method to derive flow tilt angles and mean vertical velocities from lidar has several advantages compared to sonic anemometry; there is no flow distortion caused by the instrument itself, there are no temperature effects and the instrument misalignment can be corrected for by assuming zero tilt angle at high altitudes. Contrary to mast-based instruments, the lidar measures the wind field with the exact same alignment error at a multitude of heights. Disadvantages with estimating vertical velocities from a lidar compared to mast-based measurements are potentially slightly increased levels of statistical errors due to limited sampling time, because the sampling is disjunct, and a requirement for homogeneous flow. The estimated mean vertical velocity is biased if the flow over the scanned circle is not homogeneous. It is demonstrated that the error on the mean vertical velocity due to flow inhomogeneity can be approximated by a function of the angle of the lidar beam to the vertical and the vertical gradient of the mean vertical velocity, whereas the error due to flow inhomogeneity on the horizontal mean wind speed is independent of the lidar beam angle. For the presented measurements over forest, it is evaluated that the systematic error due to the inhomogeneity of the flow is less than 0.2°. The results of the vertical conical scans were promising, and yielded positive flow angles for a sector where the forest is fetch-limited. However, more data and analysis are needed for a complete evaluation of the lidar technique.

Accuracy of the vertical tube shift method in identifying the relationship between the third molars and the mandibular canal.

PubMed

de-Azevedo-Vaz, Sergio Lins; Oenning, Anne Caroline Costa; Felizardo, Marcela Graciano; Haiter-Neto, Francisco; de Freitas, Deborah Queiroz

2015-04-01

The objective of this study is to assess the accuracy of the vertical tube shift method in identifying the relationship between the mandibular canal (MC) and third molars. Two examiners assessed image sets of 173 lower third molar roots (55 patients) using forced consensus. The image sets comprised two methods: PERI, two periapical radiographs (taken at 0° and -30°), and PAN, a panoramic radiograph (vertical angulation of -8°) and a periapical radiograph taken at a vertical angulation of -30°. Cone beam computed tomography (CBCT) was the reference standard in the study. The responses were recorded for position (buccal, in-line with apex and lingual) and contact (present or absent). The McNemar-Bowker and McNemar tests were used to determine if the PERI and PAN methods would disagree with the reference standard (α = 5 %). The PERI and PAN methods disagreed with the reference standard for both position and contact (p < 0.05). The vertical tube shift method was not accurate in determining the relationship between lower third molars and the MC. The vertical tube shift is not a reliable method for predicting the relationship between lower third molars and the MC.

A pepper-pot emittance meter for low-energy heavy-ion beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kremers, H. R.; Beijers, J. P. M.; Brandenburg, S.

2013-02-15

A novel emittance meter has been developed to measure the four-dimensional, transverse phase-space distribution of a low-energy ion beam using the pepper-pot technique. A characteristic feature of this instrument is that the pepper-pot plate, which has a linear array of holes in the vertical direction, is scanned horizontally through the ion beam. This has the advantage that the emittance can also be measured at locations along the beam line where the beam has a large horizontal divergence. A set of multi-channel plates, scintillation screen, and ccd camera is used as a position-sensitive ion detector allowing a large range of beammore » intensities that can be handled. This paper describes the design, construction, and operation of the instrument as well as the data analysis used to reconstruct the four-dimensional phase-space distribution of an ion beam. Measurements on a 15 keV He{sup +} beam are used as an example.« less

The effect of vertical bracket positioning on torque and the resultant stress in the periodontal ligament--a finite element study.

PubMed

Sardarian, Ahmadreza; Danaei, Shahla Momeni; Shahidi, Shoaleh; Boushehri, Sahar Ghodsi; Geramy, Allahyar

2014-01-01

The ideal built-in tip and torque values of the straight wire appliance reduce the need for wire bending and hence reduce chair time. The vertical position of the bracket on the tooth surface can alter the torque exerted on the tooth. This is a result of the altered surface curvature observed at each vertical position. To further clarify the role of vertical bracket positioning on the applied torque and the resultant stresses in the periodontal ligament (PDL), we designed a mandibular first premolar using finite element modeling. Cone beam computed tomography of 52 patients (83 lower first premolars) was selected to be included in the study. Curvature was measured for points along the labial surface with increasing distances (0.5 mm increments) from the cusp tip by calculating the angle between tangents drawn from these points and the axis joining the cusp tip and the root apex. The mean values for each distance were calculated, and a finite element model was designed incorporating these mean values. The resultant stress and hydrostatic pressure in the PDL were calculated using finite element analysis. The labial surface of the mandibular first premolar demonstrated a 26.39° change from 2.5 to 6 mm from the cusp tip. The maximum Von-Mises stress and hydrostatic pressure in the PDL were observed at the root apex for all of the bracket positions, and these values demonstrated, respectively, a change of up to 0.059 and 0.186 MPa between two successive points. It can be concluded that the variation in the vertical position of the bracket can have an important effect on the torque and subsequently on the stresses and pressures in the PDL.

Estimation of the peak entrance surface air kerma for patients undergoing computed tomography-guided procedures.

PubMed

Avilés Lucas, P; Dance, D R; Castellano, I A; Vañó, E

2005-01-01

The purpose of this work was to develop a method for estimating the patient peak entrance surface air kerma from measurements using a pencil ionisation chamber on dosimetry phantoms exposed in a computed tomography (CT) scanner. The method described is especially relevant for CT fluoroscopy and CT perfusion procedures where the peak entrance surface air kerma is the risk-related quantity of primary concern. Pencil ionisation chamber measurements include scattered radiation, which is outside the primary radiation field, and that must be subtracted in order to derive the peak entrance surface air kerma. A Monte Carlo computer model has therefore been used to calculate correction factors, which may be applied to measurements of the CT dose index obtained using a pencil ionisation chamber in order to estimate the peak entrance surface air kerma. The calculations were made for beam widths of 5, 7, 10 and 20 mm, for seven positions of the phantom, and for the geometry of a GE HiSpeed CT/i scanner. The program was validated by comparing measurements and calculations of CTDI for various vertical positions of the phantom and by directly estimating the peak ESAK using the program. Both validations showed agreement within statistical uncertainties (standard deviation of 2.3% or less). For the GE machine, the correction factors vary by approximately 10% with slice width for a fixed phantom position, being largest for the 20 mm beam width, and at that beam width range from 0.87 when the phantom surface is at the isocentre to 1.23 when it is displaced vertically by 24 cm.

16. DETAIL OF FLOOR BEAMS & VERTICAL PIER MEMBERS WITH ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

16. DETAIL OF FLOOR BEAMS & VERTICAL PIER MEMBERS WITH CROSS HATCH PATTERN INDICATING PREVIOUS USAGE OF MATERIALS, VIEW NORTH - Cottrell Road Bridge, Spanning CSX Transportation tracks, Vassar, Tuscola County, MI

Ultra-low-frequency vertical vibration isolator based on a two-stage beam structure for absolute gravimetry.

PubMed

Wang, G; Wu, K; Hu, H; Li, G; Wang, L J

2016-10-01

To reduce seismic and environmental vibration noise, ultra-low-frequency vertical vibration isolation systems play an important role in absolute gravimetry. For this purpose, an isolator based on a two-stage beam structure is proposed and demonstrated. The isolator has a simpler and more robust structure than the present ultra-low-frequency vertical active vibration isolators. In the system, two beams are connected to a frame using flexural pivots. The upper beam is suspended from the frame with a normal hex spring and the lower beam is suspended from the upper one using a zero-length spring. The pivot of the upper beam is not vertically above the pivot of the lower beam. With this special design, the attachment points of the zero-length spring to the beams can be moved to adjust the effective stiffness. A photoelectric detector is used to detect the angle between the two beams, and a voice coil actuator attached to the upper beam is controlled by a feedback circuit to keep the angle at a fixed value. The system can achieve a natural period of 100 s by carefully moving the attachment points of the zero-length spring to the beams and tuning the feedback parameters. The system has been used as an inertial reference in the T-1 absolute gravimeter. The experiment results demonstrate that the system has significant vibration isolation performance that holds promise in applications such as absolute gravimeters.

Ultra-low-frequency vertical vibration isolator based on a two-stage beam structure for absolute gravimetry

NASA Astrophysics Data System (ADS)

Wang, G.; Wu, K.; Hu, H.; Li, G.; Wang, L. J.

2016-10-01

To reduce seismic and environmental vibration noise, ultra-low-frequency vertical vibration isolation systems play an important role in absolute gravimetry. For this purpose, an isolator based on a two-stage beam structure is proposed and demonstrated. The isolator has a simpler and more robust structure than the present ultra-low-frequency vertical active vibration isolators. In the system, two beams are connected to a frame using flexural pivots. The upper beam is suspended from the frame with a normal hex spring and the lower beam is suspended from the upper one using a zero-length spring. The pivot of the upper beam is not vertically above the pivot of the lower beam. With this special design, the attachment points of the zero-length spring to the beams can be moved to adjust the effective stiffness. A photoelectric detector is used to detect the angle between the two beams, and a voice coil actuator attached to the upper beam is controlled by a feedback circuit to keep the angle at a fixed value. The system can achieve a natural period of 100 s by carefully moving the attachment points of the zero-length spring to the beams and tuning the feedback parameters. The system has been used as an inertial reference in the T-1 absolute gravimeter. The experiment results demonstrate that the system has significant vibration isolation performance that holds promise in applications such as absolute gravimeters.

Direct Observation of Ultralow Vertical Emittance using a Vertical Undulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wootton, Kent

2015-09-17

In recent work, the first quantitative measurements of electron beam vertical emittance using a vertical undulator were presented, with particular emphasis given to ultralow vertical emittances [K. P. Wootton, et al., Phys. Rev. ST Accel. Beams, 17, 112802 (2014)]. Using this apparatus, a geometric vertical emittance of 0.9 ± 0.3 pm rad has been observed. A critical analysis is given of measurement approaches that were attempted, with particular emphasis on systematic and statistical uncertainties. The method used is explained, compared to other techniques and the applicability of these results to other scenarios discussed.

Operation of the CESR-TA vertical beam size monitor at Eb = 4 GeV

NASA Astrophysics Data System (ADS)

Alexander, J. P.; Conolly, C.; Edwards, E.; Flanagan, J. W.; Fontes, E.; Heltsley, B. K.; Lyndaker, A.; Peterson, D. P.; Rider, N. T.; Rubin, D. L.; Seeley, R.; Shanks, J.

2015-10-01

We describe operation of the CESR-TA vertical beam size monitor (xBSM) with e± beams with Eb=4 GeV. The xBSM measures vertical beam size by imaging synchrotron radiation x-rays through an optical element onto a detector array of 32 InGaAs photodiodes with 50 μm pitch. The device has previously been successfully used to measure vertical beam sizes of 10-100 μm on a bunch-by-bunch, turn-by-turn basis at e± beam energies of ~2 GeV and source magnetic fields below 2.8 kG, for which the detector required calibration for incident x-rays of 1-5 keV. At Eb = 4.0 GeV and B=4.5 kG, however, the incident synchrotron radiation spectrum extends to ~20 keV, requiring calibration of detector response in that regime. Such a calibration is described and then used to analyze data taken with several different thicknesses of filters in front of the detector. We obtain a relative precision of better than 4% on beam size measurement from 15 to 100 μm over several different ranges of x-ray energy, including both 1-12 keV and 6-17 keV. The response of an identical detector, but tilted vertically by 60° in order to increase magnification without a longer beamline, is measured and shown to improve x-ray detection above 4 keV without compromising sensitivity to beam size. We also investigate operation of a coded aperture using gold masking backed by synthetic diamond.

ONLINE MINIMIZATION OF VERTICAL BEAM SIZES AT APS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Yipeng

In this paper, online minimization of vertical beam sizes along the APS (Advanced Photon Source) storage ring is presented. A genetic algorithm (GA) was developed and employed for the online optimization in the APS storage ring. A total of 59 families of skew quadrupole magnets were employed as knobs to adjust the coupling and the vertical dispersion in the APS storage ring. Starting from initially zero current skew quadrupoles, small vertical beam sizes along the APS storage ring were achieved in a short optimization time of one hour. The optimization results from this method are briefly compared with the onemore » from LOCO (Linear Optics from Closed Orbits) response matrix correction.« less

Launch and capture of a single particle in a pulse-laser-assisted dual-beam fiber-optic trap

NASA Astrophysics Data System (ADS)

Fu, Zhenhai; She, Xuan; Li, Nan; Hu, Huizhu

2018-06-01

The rapid loading and manipulation of microspheres in optical trap is important for its applications in optomechanics and precision force sensing. We investigate the microsphere behavior under coaction of a dual-beam fiber-optic trap and a pulse laser beam, which reveals a launched microsphere can be effectively captured in a spatial region. A suitable order of pulse duration for launch is derived according to the calculated detachment energy threshold of pulse laser. Furthermore, we illustrate the effect of structural parameters on the launching process, including the spot size of pulse laser, the vertical displacement of beam waist and the initial position of microsphere. Our result will be instructive in the optimal design of the pulse-laser-assisted optical tweezers for controllable loading mechanism of optical trap.

Measurement of ultra-low ion energy of decelerated ion beam using a deflecting electric field

NASA Astrophysics Data System (ADS)

Thopan, P.; Suwannakachorn, D.; Tippawan, U.; Yu, L. D.

2015-12-01

In investigation on ultra-low-energy ion bombardment effect on DNA, an ion beam deceleration lens was developed for high-quality ultra-low-energy ion beam. Measurement of the ion energy after deceleration was necessary to confirm the ion beam really decelerated as theoretically predicted. In contrast to conventional methods, this work used a simple deflecting electrostatic field after the deceleration lens to bend the ion beam. The beam bending distance depended on the ion energy and was described and simulated. A system for the measurement of the ion beam energy was constructed. It consisted of a pair of parallel electrode plates to generate the deflecting electrical field, a copper rod measurement piece to detect ion beam current, a vernier caliper to mark the beam position, a stepping motor to translate the measurement rod, and a webcam-camera to read the beam bending distance. The entire system was installed after the ion-beam deceleration lens inside the large chamber of the bioengineering vertical ion beam line. Moving the measurement rod across the decelerated ion beam enabled to obtain beam profiles, from which the beam bending distance could be known and the ion beam energy could be calculated. The measurement results were in good agreement with theoretical and simulated results.

Comparison of turbulence estimation for four- and five-beam ADCP configurations

NASA Astrophysics Data System (ADS)

Togneri, Michael; Masters, Ian; Jones, Dale

2017-04-01

Turbulence is a vital consideration for tidal power generation, as the resulting fluctuating loads greatly impact the fatigue life of tidal turbines and their components. Acoustic Doppler current profilers (ADCPs) are one of the most common tools for measurement of currents in tidal power applications, and although most often used for assessment of mean current properties they are also capable of measuring turbulence parameters. Conventional ADCPs use four diverging beams in a so-called 'Janus' configuration, but more recent models employ an additional vertical beam. In this paper we explore the improvements to turbulence measurements that are made possible by the addition of the fifth beam, with a focus on estimation of turbulent kinetic energy (TKE) density. The standard approach for estimating TKE density from ADCP measurements is the variance method. As each of the diverging beams measures a single velocity component at spatially-separated points, it is not possible to find the TKE density by a straightforward combination of beam measurements. Instead, we must assume that the statistical properties of the turbulence are uniform across the spatial extent of the beams; it is then possible to express the TKE density as a linear combination of the velocity variance as measured by each beam. In the four-beam configuration, an additional assumption regarding the magnitude of the turbulent anisotropy: a parameter ξ is introduced that characterises the proportion of TKE in the vertical fluctuations. With the five-beam configuration, direct measurements of the vertical component are available and this assumption is no longer required. In this paper, turbulence measurements from a five-beam ADCP deployed off the coast of Anglesey in 2014 are analysed. We compare turbulence estimates using all five beams to estimates obtained using only the conventional four-beam setup by discarding the vertical beam data. This allows us to quantify the error in the standard value of ξ. We find that it is on average within 3.4% of the real value, although there are times for which it is much greater. We also discuss the Doppler noise correction in the five-beam case, which is more complex than the four-beam case due to the different noise properties of the vertical beam.

Accuracy of off-line bioluminescence imaging to localize targets in preclinical radiation research.

PubMed

Tuli, Richard; Armour, Michael; Surmak, Andrew; Reyes, Juvenal; Iordachita, Iulian; Patterson, Michael; Wong, John

2013-04-01

In this study, we investigated the accuracy of using off-line bioluminescence imaging (BLI) and tomography (BLT) to guide irradiation of small soft tissue targets on a small animal radiation research platform (SARRP) with on-board cone beam CT (CBCT) capability. A small glass bulb containing BL cells was implanted as a BL source in the abdomen of 11 mouse carcasses. Bioluminescence imaging and tomography were acquired for each carcass. Six carcasses were setup visually without immobilization and 5 were restrained in position with tape. All carcasses were setup in treatment position on the SARRP where the centroid position of the bulb on CBCT was taken as "truth". In the 2D visual setup, the carcass was setup by aligning the point of brightest luminescence with the vertical beam axis. In the CBCT assisted setup, the pose of the carcass on CBCT was aligned with that on the 2D BL image for setup. For both 2D setup methods, the offset of the bulb centroid on CBCT from the vertical beam axis was measured. In the BLT-CBCT fusion method, the 3D torso on BLT and CBCT was registered and the 3D offset of the respective source centroids was calculated. The setup results were independent of the carcass being immobilized or not due to the onset of rigor mortis. The 2D offset of the perceived BL source position from the CBCT bulb position was 2.3 mm ± 1.3 mm. The 3D offset between BLT and CBCT was 1.5 mm ± 0.9 mm. Given the rigidity of the carcasses, the setup results represent the best that can be achieved with off-line 2D BLI and 3D BLT. The setup uncertainty would require the use of undesirably large margin of 4-5 mm. The results compel the implementation of on-board BLT capability on the SARRP to eliminate setup error and to improve BLT accuracy.

Accuracy of Off-Line Bioluminescence Imaging to Localize Targets in Preclinical Radiation Research

PubMed Central

Tuli, Richard; Armour, Michael; Surmak, Andrew; Reyes, Juvenal; Iordachita, Iulian; Patterson, Michael; Wong, John

2013-01-01

In this study, we investigated the accuracy of using off-line bioluminescence imaging (BLI) and tomography (BLT) to guide irradiation of small soft tissue targets on a small animal radiation research platform (SARRP) with on-board cone beam CT (CBCT) capability. A small glass bulb containing BL cells was implanted as a BL source in the abdomen of 11 mouse carcasses. Bioluminescence imaging and tomography were acquired for each carcass. Six carcasses were setup visually without immobilization and 5 were restrained in position with tape. All carcasses were setup in treatment position on the SARRP where the centroid position of the bulb on CBCT was taken as “truth”. In the 2D visual setup, the carcass was setup by aligning the point of brightest luminescence with the vertical beam axis. In the CBCT assisted setup, the pose of the carcass on CBCT was aligned with that on the 2D BL image for setup. For both 2D setup methods, the offset of the bulb centroid on CBCT from the vertical beam axis was measured. In the BLT-CBCT fusion method, the 3D torso on BLT and CBCT was registered and the 3D offset of the respective source centroids was calculated. The setup results were independent of the carcass being immobilized or not due to the onset of rigor mortis. The 2D offset of the perceived BL source position from the CBCT bulb position was 2.3 mm ± 1.3 mm. The 3D offset between BLT and CBCT was 1.5 mm ± 0.9 mm. Given the rigidity of the carcasses, the setup results represent the best that can be achieved with off-line 2D BLI and 3D BLT. The setup uncertainty would require the use of undesirably large margin of 4–5 mm. The results compel the implementation of on-board BLT capability on the SARRP to eliminate setup error and to improve BLT accuracy. PMID:23578189

RHIC BPM SYSTEM MODIFICATIONS AND PERFORMANCE.

DOE Office of Scientific and Technical Information (OSTI.GOV)

SATOGATA, T.; CALAGA, R.; CAMERON, P.

2005-05-16

The RHIC beam position monitor (BPM) system provides independent average orbit and turn-by-turn (TBT) position measurements. In each ring, there are 162 measurement locations per plane (horizontal and vertical) for a total of 648 BPM planes in the RHIC machine. During 2003 and 2004 shutdowns, BPM processing electronics were moved from the RHIC tunnel to controls alcoves to reduce radiation impact, and the analog signal paths of several dozen modules were modified to eliminate gain-switching relays and improve signal stability. This paper presents results of improved system performance, including stability for interaction region beam-based alignment efforts. We also summarize performancemore » of recently-added DSP profile scan capability, and improved million-turn TBT acquisition channels for 10 Hz triplet vibration, nonlinear dynamics, and echo studies.« less

Mechanical design control and implementation of a new movable intensity profile beamline monitor for the TRIUMF parity experiment 497

NASA Astrophysics Data System (ADS)

Ries, Thomas C.

1995-05-01

Two new movable beam intensity profile monitors have been installed into the TRIUMF Parity Experiment 497 Beamlines. Each unit serves two functions. Firstly, the beam median position, in a plane normal to the beam, is detected by split plate Secondary Emission Monitors. This information is used to lock the beam into the position of the movable monitor to within a few μm's via high band width ferrite core steering magnets operating in tandem in a closed loop servo feedback control system. Secondly, the beam profile and intensity is detected via a multi-wire secondary emission non-movable monitor, where the data provides high precision values regarding centroidal positions and profiles. The centroid position of the beam is statistically determined to an accuracy of ±10 μm from a data record length of 1 second. The design of each device adheres to strict standards of mechanically rigid construction. The split plate SEM accuracy and repeatability is better than 15 μm with an absolute resolution limit of 0.4 μm. Maximum travel is 2 inches in the vertical plane. Since the device is mechanically modular and both degrees of freedom are combined into a single mechanical unit, fast and easy handling is possible for maintenance in radioactive areas. The actuators are dc servo motors with tachometers driven by linear servo power amplifiers. These amplifiers are used in lieu of pulse width modulated amps to eliminate noise produced by the switching circuits. Position sensing is done by variable reluctance type absolute rotary encoders providing 16 bit resolution over the full range of travel. Positioning is done manually using a self centring potentiometer on the control panel that provides a ± velocity command signal to the power amplifiers. This configuration ensures good controllability over a very large range of positioning speeds hence making 0.4 μm incremental positioning possible, as well as, fast relocations over large relative distances. The precision movement and jitter was measured in the laboratory. Examples will be given of the monitor use with beam.

Single Pass Stripline Beam Position Monitor Design, Fabrication and Commissioning

NASA Astrophysics Data System (ADS)

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

2012-10-01

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

Cavity Solitons in Vertical Cavity Surface Emitting Lasers and their Applications

NASA Astrophysics Data System (ADS)

Giudici, Massimo; Pedaci, Francesco; Caboche, Emilie; Genevet, Patrice; Barland, Stephane; Tredicce, Jorge; Tissoni, Giovanna; Lugiato, Luigi

Cavity solitons (CS) are single peak localized structures which form over a homogeneous background in the section of broad-area non linear resonator driven by a coherent holding beam. They can be switched on and off by shining a writing/ erasing local laser pulse into the optical cavity. Moreover, when a phase or amplitude gradient is introduced in the holding beam, CS are set in motion along the gradient with a speed that depends on gradient strength. The ability to address CS and to control their location as well as their motion makes them interesting for alloptical processing units. In this chapter we report on several functionalities of CS that have been experimentally implemented in a Vertical Cavity Surface Emitting Laser (VCSEL) biased below threshold. We show that CS positions in the transverse section of the resonator can be reconfigured according to a phase landscape introduced in the holding beam. CS drifting propelled by a phase gradient in the holding beam can be used for realizing an all-optical delay line. Information bits are written in form of CS at a point of the device and a time delayed version of the written information can be read elsewhere along the gradient direction. CS existence and functionalities are deeply affected by presence of device defects generated during the fabrication process and randomly distributed through the device section. The sensitivity of CS to parameters gradients can be used to probe these defects, otherwise not detectable, and mapping their positions. Finally, a periodic flow of moving CS can be obtained by the interplay between a device defect and an external parameter gradient. This suggests the possibility of engineering a CS source directly onto the device.

Comparative study between REAP 200 and FEP171 CAR with 50-kV raster e-beam system for sub-100-nm technology

NASA Astrophysics Data System (ADS)

Baik, Ki-Ho; Lem, Homer Y.; Dean, Robert L.; Osborne, Stephen; Mueller, Mark; Abboud, Frank E.

2003-08-01

In this paper, a process established with a positive-tone chemically amplified resist (CAR) from TOK REAP200 and Fujifilm Arch FEP171 and 50kV MEBES system is discussed. This TOK resist is developed for raster scan 50 kV e-beam systems. It has high contrast, good coating characteristics, good dry etch selectivity, and high environmental stability. In the mask industries, the most popular positive tone CAR is FEP171, which is a high activation energy type CAR. REAP (Raster E-beam Advanced Process) 200 is low activation energy type and new acetal protecting polymer. In this study, we compared to these different type resists in terms of contrast, PAB and PEB latitude, resist profile, footing, T-topping, PED stability, LER, Global CDU (Critical Dimension Uniformity) and resolution. The REAP200 Resist obtained 75nm isolated lines and spaces, 90nm dense patterns with vertical profile, and a good stability of delay time.

Lattice modeling and application of independent component analysis to high power, long bunch beams in the Los Alamos Proton Storage Ring

NASA Astrophysics Data System (ADS)

Kolski, Jeffrey

The linear lattice properties of the Proton Storage Ring (PSR) at the Los Alamos Neutron Science Center (LANSCE) in Los Alamos, NM were measured and applied to determine a better linear accelerator model. We found that the initial model was deficient in predicting the vertical focusing strength. The additional vertical focusing was located through fundamental understanding of experiment and statistically rigorous analysis. An improved model was constructed and compared against the initial model and measurement at operation set points and set points far away from nominal and was shown to indeed be an enhanced model. Independent component analysis (ICA) is a tool for data mining in many fields of science. Traditionally, ICA is applied to turn-by-turn beam position data as a means to measure the lattice functions of the real machine. Due to the diagnostic setup for the PSR, this method is not applicable. A new application method for ICA is derived, ICA applied along the length of the bunch. The ICA modes represent motions within the beam pulse. Several of the dominate ICA modes are experimentally identified.

Optical bandgap modelling from the structural arrangement of carbon nanotubes.

PubMed

Butler, Timothy P; Rashid, Ijaz; Montelongo, Yunuen; Amaratunga, Gehan A J; Butt, Haider

2018-06-14

The optical bandgap properties of vertically-aligned carbon nanotube (VACNT) arrays were probed through their interaction with white light, with the light reflected from the rotating arrays measured with a spectrometer. The precise deterministic control over the structure of vertically-aligned carbon nanotube arrays through electron beam lithography and well-controlled growth conditions brings with it the ability to produce exotic photonic crystals over a relatively large area. The characterisation of the behaviour of these materials in the presence of light is a necessary first step toward application. Relatively large area array structures of high-quality VACNTs were fabricated in square, hexagonal, circular and pseudorandom patterned arrays with length scales on the order of those of visible light for the purpose of investigating how they may be used to manipulate an impinging light beam. In order to investigate the optical properties of these arrays a set of measurement apparatus was designed which allowed the accurate measurement of their optical bandgap characteristics. The patterned samples were rotated under the illuminating white light beam, revealing interesting optical bandgap results caused by the changing patterns and relative positions of the scattering elements (VACNTs).

Reactor hold-down arrangement

DOEpatents

McCugh, Ralph

1976-05-25

A nuclear reactor contains an assembly of moderator blocks, laid end-to-end, one on top of another, and alongside one another, which blocks are restrained by vertical beams at each side of the assembly, fixed horizontal beams surrounding the assembly at the top and bottom and springs connecting the fixed horizontal beams and the ends of the vertical beams in such a way as to permit relatively high expansion midway of the height of the assembly while restricting expansion near the top of the assembly.

A NOTE ON THE RELATIVE PHOTOSENSORY EFFECT OF POLARIZED LIGHT

PubMed Central

Crozier, W. J.; Mangelsdorf, A. F.

1924-01-01

Experiments were made to compare the stimulating effectiveness of vertically and horizontally polarized lights and non-polarized lights of equal intensity upon phototropic movements of the beetle Tetraopes tetraopthalmus; and to compare the effectiveness of two light beams polarized at right angles to one another upon phototropic orientation of the land isopod Cylisticus convexus. Tetraopes is positively, and Cylisticus, negatively phototropic. Tests were also made of the intensities of horizontally and of vertically polarized light required to inhibit stereotropism in larvæ of Tenebrio. Under the conditions of the tests, no certain qualitative effect connected with polarization could be detected. PMID:19872110

Pink-Beam, Highly-Accurate Compact Water Cooled Slits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lyndaker, Aaron; Deyhim, Alex; Jayne, Richard

2007-01-19

Advanced Design Consulting, Inc. (ADC) has designed accurate compact slits for applications where high precision is required. The system consists of vertical and horizontal slit mechanisms, a vacuum vessel which houses them, water cooling lines with vacuum guards connected to the individual blades, stepper motors with linear encoders, limit (home position) switches and electrical connections including internal wiring for a drain current measurement system. The total slit size is adjustable from 0 to 15 mm both vertically and horizontally. Each of the four blades are individually controlled and motorized. In this paper, a summary of the design and Finite Elementmore » Analysis of the system are presented.« less

Determination of beam-position dependent transfer functions of LCR-G gravimeters by means of moving mass calibration device in the Mátyáshegy Gravity and Geodynamical Observatory, Budapest

NASA Astrophysics Data System (ADS)

Koppán, András; Kis, Márta; Merényi, László; Papp, Gábor; Benedek, Judit; Meurers, Bruno

2017-04-01

In this presentation authors propose a method for the determination of transfer characteristics and fine calibration of LCR relative gravimeters used for earth-tide recordings, by means of the moving-mass gravimeter calibration device of Budapest-Mátyáshegy Gravity and Geodynamical Observatory. Beam-position dependent transfer functions of four relative LCR G type gravimeters were determined and compared. In order to make these instruments applicable for observatory tidal recordings, there is a need for examining the unique characteristics of equipments and adequately correcting these inherent distorting effects. Thus, the sensitivity for the tilting, temporal changes of scale factors and beam-position dependent transfer characteristics are necessary to be determined for observatory use of these instruments. During the calibration a cylindrical ring of 3200 kg mass is vertically moving around the equipment, generating gravity variations. The effect of the moving mass can be precisely calculated from the known mass and geometrical parameters. The maximum theoretical gravity variation produced by the vertical movement of the mass is ab. 110 microGal, so it provides excellent possibility for the fine calibration of gravimeters in the tidal range. Magnetic experiments were also carried out on the pillar of the calibration device as well, in order to analyse the magnetic effect of the moving stainless steel-mass. According to the magnetic measurements, a correction for the magnetic effect was applied on the measured gravimetric data series. The calibration process is aided by intelligent controller electronics. A PLC-based system has been developed to allow easy control of the movement of the calibrating mass and to measure the mass position. It enables also programmed steps of movements (waiting positions and waiting times) for refined gravity changes. All parameters (position of the mass, CPI data, X/Y leveling positions) are recorded with 1/sec. sampling rate. The system can be controlled remotely through the internet. Authors wish to express their thanks to OTKA (Hungarian Scientific Research Fund) for their support (OTKA-K101603, OTKA K109060).

Emittance and lifetime measurement with damping wigglers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, G. M.; Shaftan, T., E-mail: shaftan@bnl.gov; Cheng, W. X.

National Synchrotron Light Source II (NSLS-II) is a new third-generation storage ring light source at Brookhaven National Laboratory. The storage ring design calls for small horizontal emittance (<1 nm-rad) and diffraction-limited vertical emittance at 12 keV (8 pm-rad). Achieving low value of the beam size will enable novel user experiments with nm-range spatial and meV-energy resolution. The high-brightness NSLS-II lattice has been realized by implementing 30-cell double bend achromatic cells producing the horizontal emittance of 2 nm rad and then halving it further by using several Damping Wigglers (DWs). This paper is focused on characterization of the DW effects inmore » the storage ring performance, namely, on reduction of the beam emittance, and corresponding changes in the energy spread and beam lifetime. The relevant beam parameters have been measured by the X-ray pinhole camera, beam position monitors, beam filling pattern monitor, and current transformers. In this paper, we compare the measured results of the beam performance with analytic estimates for the complement of the 3 DWs installed at the NSLS-II.« less

Ion related problems for the XLS ring

NASA Astrophysics Data System (ADS)

Bozoki, Eva S.; Halama, Henry

1991-10-01

The electron beam in a storage ring collides with the residual gas in the vacuum chamber. As a consequence, low velocity positive ions are produced and trapped in the potential well of the electron beam. They perform stable or unstable oscillations around the beam under the repetitive Coulomb force of the bunches. If not cleared, the captured ions can lead to partial or total neutralization of the beam, causing both a decrease of lifetime and a change in the vertical tunes as well as an increase in the tune spread. It can also cause coherent and incoherent transverse instabilities. An electrostatic clearing electrodes system was designed to keep the neutralization below a desired limit. The location and the geometry of the clearing electrodes as well as the applied clearing voltage is based on the study of the ion production rate, longitudinal velocity of ions in field-free regions and in the dipoles, beam self-electric field, beam potential, critical mass for ion capture in the bunched beam and the bounce frequencies of the ions, tune shift and pressure rise due to trapped ions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ody, A.; Musumeci, P.; Maxson, J.

In this study we discuss the application of the flat beam transform to generate beams suitable for injection into slab-symmetric dielectric laser-driven accelerators (DLAs). A study of the focusing requirements to keep the particles within the tight apertures characterizing these accelerators shows the benefits of employing ultralow beam emittances. The slab geometry of the many dielectric accelerating structures strongly favors the use of flat beams with large ratio between vertical and horizontal emittances. We employ particle tracking simulations to study the application of the flat beam transform for two injector designs, a DC non relativistic photogun and a 1.6 cellmore » S-band RF photoinjector, obtaining in both cases emittance ratios between the horizontal and vertical plane in excess of 100 in agreement with simple analytical estimates. The 4 MeV RF photoinjector study-case can be directly applied to the UCLA Pegasus beamline and shows normalized emittances down to < 3 nm in the vertical dimension for beam charges up to 20 fC, enabling a two-stage DLA experiment.« less

Emittance matching of a slow extracted beam for a rotating gantry

NASA Astrophysics Data System (ADS)

Fujimoto, T.; Iwata, Y.; Matsuba, S.; Fujita, T.; Sato, S.; Shirai, T.; Noda, K.

2017-09-01

The introduction of a heavy-ion rotating gantry is in progress at the Heavy Ion Medical Accelerator in Chiba (HIMAC) for realizing high-precision cancer therapy using heavy ions. A scanning irradiation method will be applied to this gantry course with 48-430 MeV/u beam energy. In the rotating gantry, the horizontal and vertical beam parameters are coupled by its rotation. To maintain a circular spot shape at the isocenter irrespective of the gantry angle, achieving symmetric phase space distribution of the horizontal and vertical beam at the entrance of the rotating gantry is necessary. Therefore, compensating the horizontal and vertical emittance is necessary. We consider using a thin scatterer method to compensate the emittance. After considering the optical design for emittance matching, the scatterer device is located in the high-energy beam transport line. In the beam commissioning, we confirm that the symmetrical spot shape is obtained at the isocenter without depending on the gantry angle.

Characterization of the Shielded Neutron Source at Triangle Universities Nuclear Laboratory

NASA Astrophysics Data System (ADS)

Hobson, Chad; Finch, Sean; Howell, Calvin; Malone, Ron; Tornow, Wernew

2016-09-01

In 2015, Triangle Universities Nuclear Laboratory rebuilt its shielded neutron source (SNS) with the goal of improving neutron beam collimation and reducing neutron and gamma-ray backgrounds. Neutrons are produced via the 2H(d,n)3He reaction and then collimated by heavy shielding to form a beam. The SNS has the ability to produce both a rectangular and circular neutron beam through use of two collimators with different beam apertures. Our work characterized both the neutron beam profiles as well as the neutron and gamma-ray backgrounds at various locations around the SNS. This characterization was performed to provide researchers who use the SNS with beam parameters necessary to plan and conduct an experiment. Vertical and horizontal beam profiles were measured at two different distances from the neutron production cell by scanning a small plastic scintillator across the face of the beam at various energies for each collimator. Background neutron and gamma-ray intensities were measured using time-of-flight techniques at 10 MeV and 16 MeV with the rectangular collimator. We present results on the position and size of neutron beam as well as on the structure and magnitude of the backgrounds.

Flat electron beam sources for DLA accelerators

DOE PAGES

Ody, A.; Musumeci, P.; Maxson, J.; ...

2016-10-26

In this study we discuss the application of the flat beam transform to generate beams suitable for injection into slab-symmetric dielectric laser-driven accelerators (DLAs). A study of the focusing requirements to keep the particles within the tight apertures characterizing these accelerators shows the benefits of employing ultralow beam emittances. The slab geometry of the many dielectric accelerating structures strongly favors the use of flat beams with large ratio between vertical and horizontal emittances. We employ particle tracking simulations to study the application of the flat beam transform for two injector designs, a DC non relativistic photogun and a 1.6 cellmore » S-band RF photoinjector, obtaining in both cases emittance ratios between the horizontal and vertical plane in excess of 100 in agreement with simple analytical estimates. The 4 MeV RF photoinjector study-case can be directly applied to the UCLA Pegasus beamline and shows normalized emittances down to < 3 nm in the vertical dimension for beam charges up to 20 fC, enabling a two-stage DLA experiment.« less

Observations of vertical velocities in the tropical upper troposphere and lower stratosphere using the Arecibo 430-MHz radar

NASA Technical Reports Server (NTRS)

Cornish, C. R.

1988-01-01

The first clear-air observations of vertical velocities in the tropical upper troposphere and lower stratosphere (8-22 km) using the Arecibo 430-MHz radar are presented. Oscillations in the vertical velocity near the Brunt-Vaisala period are observed in the lower stratosphere during the 12-hour observation period. Frequency power spectra from the vertical velocity time series show a slope between -0.5 and -1.0. Vertical wave number spectra computed from the height profiles of vertical velocities have slopes between -1.0 and -1.5. These observed slopes do not agree well with the slopes of +1/3 and -2.5 for frequency and vertical wave number spectra, respectively, predicted by a universal gravity-wave spectrum model. The spectral power of wave number spectra of a radial beam directed 15 deg off-zenith is enhanced by an order of magnitude over the spectral power levels of the vertical beam. This enhancement suggests that other geophysical processes besides gravity waves are present in the horizontal flow. The steepening of the wave number spectrum of the off-vertical beam in the lower stratosphere to near -2.0 is attributed to a quasi-inertial period wave, which was present in the horizontal flow during the observation period.

Measurement of Systematic Error Effects for a Sensitive Storage Ring EDM Polarimeter

NASA Astrophysics Data System (ADS)

Imig, Astrid; Stephenson, Edward

2009-10-01

The Storage Ring EDM Collaboration was using the Cooler Synchrotron (COSY) and the EDDA detector at the Forschungszentrum J"ulich to explore systematic errors in very sensitive storage-ring polarization measurements. Polarized deuterons of 235 MeV were used. The analyzer target was a block of 17 mm thick carbon placed close to the beam so that white noise applied to upstream electrostatic plates increases the vertical phase space of the beam, allowing deuterons to strike the front face of the block. For a detector acceptance that covers laboratory angles larger than 9 ^o, the efficiency for particles to scatter into the polarimeter detectors was about 0.1% (all directions) and the vector analyzing power was about 0.2. Measurements were made of the sensitivity of the polarization measurement to beam position and angle. Both vector and tensor asymmetries were measured using beams with both vector and tensor polarization. Effects were seen that depend upon both the beam geometry and the data rate in the detectors.

5-Beam ADCP Deployment Strategy Considerations

NASA Astrophysics Data System (ADS)

Moore, T.; Savidge, D. K.; Gargett, A.

2016-02-01

With the increasing availability of 5 beam ADCPs and expanding opportunities for their deployment within both observatory and dedicated process study settings, refinements in deployment strategies are needed.Measuring vertical velocities directly with a vertically oriented acoustic beam requires that the instrument be stably mounted and leveled within fractions of a degree. Leveled shallow water deployments to date have utilized divers to jet pipes into the sand for stability, manually mount the instruments on the pipes, and level them. Leveling has been guided by the deployed instrument's pitch and roll output, available in real-time because of the observatory settings in which the deployments occurred. To expand the range of feasible deployments to deeper, perhaps non-real-time capable settings, alternatives to diver deployment and leveling must be considered. To determine stability requirements, mooring motion (heading, pitch and roll) has been sampled at 1Hz by gimballed ADCPs at a range of instrument deployment depths, and in shrouded and unshrouded cages. Conditions under which ADCP cages resting on the bottom experience significant shifts in tilt, roll or heading are assessed using co-located wind and wave measurements. The accuracy of estimating vertical velocities using all five beams relative to a well leveled vertical single beam is assessed from archived high frequency five beam data, to explore whether easing the leveling requirement is feasible.

Ultra-Low Threshold Vertical-Cavity Surface-Emitting Lasers for USAF Applications

DTIC Science & Technology

2005-01-01

molecular beam epitaxy , semiconductors, finite element method, modeling and simulation, oxidation furnace 16. SECURITY CLASSIFICATION OF: 19a. NAME OF...Patterson Air Force Base). Device material growth was accomplished by means of molecular beam epitaxy (MBE) using a Varian GENII MBE system owned by the...grown by molecular beam epitaxy on a GaAs substrate. Vertical posts, with square and circular cross sections ranging in size from 5 to 40 microns

Design and Development of Emittance Measurement Device by Using the Pepper-pot Technique

NASA Astrophysics Data System (ADS)

Pakluea, S.; Rimjaem, S.

2017-09-01

Transverse emittance of a charged particle beam is one of the most important properties that reveals the quality of the beam. It is related to charge density, transvers size and angular displacement of the beam in transverse phase space. There are several techniques to measure the transverse emittance value. One of practical methods is the pepper-pot technique, which can measure both horizontal and vertical emittance value in a single measurement. This research concentrates on development of a pepper-pot device to measure the transverse emittance of electron beam produced from an accelerator injector system, which consists of a thermionic cathode RF electron gun and an alpha magnet, at the Plasma and Beam Physics Research Facility, Chiang Mai University. Simulation of beam dynamics was conducted with programs PARMELA, ELEGANT and self-developed codes using C and MATLAB. The geometry, dimensions and location of the pepper-pot as well as its corresponding screen station position were included in the simulation. The result from this study will be used to design and develop a practical pepper-pot experimental station.

Accuracy of a cone beam computed tomography-guided surgical stent for orthodontic mini-implant placement.

PubMed

Yu, Jae-Jung; Kim, Gyu-Tae; Choi, Yong-Suk; Hwang, Eui-Hwan; Paek, Janghyun; Kim, Seong-Hun; Huang, John C

2012-03-01

To validate the accuracy of a cone-beam computed tomography (CBCT)-guided surgical stent for orthodontic mini-implant (OMI) placement by quantitatively evaluating the difference between CBCT-prescribed and actual position of mini-implants in preoperative and postoperative CBCT images. A surgical stent was fabricated using Teflon-Perfluoroalkoxy, which has appropriate biological x-ray attenuation properties. Polyvinylsiloxane impression material was used to secure the custom-made surgical stent onto swine mandibles. CBCT scanning was done with the stent in place to virtually plan mini-implants using a three-dimensional (3D) software program. An appropriate insertion point was determined using 3D reconstruction data, and the vertical and horizontal angulations were determined using four prescribed angles. A custom-designed surveyor was used to drill a guide hole within the surgical stent as prescribed on the CBCT images for insertion of 32 OMIs. The mandibles with a surgical stent in place were rescanned with CBCT to measure the deviations between the virtual planning data and surgical results. The difference between the prescribed and actual vertical angle was 1.01 ± 7.25, and the horizontal difference was 1.16 ± 6.08. The correlation coefficient confirms that there was no intrarater variability in either the horizontal (R  =  .97) or vertical (R  =  .74) vectors. The surgical stent in this study guides mini-implants to the prescribed position as planned in CBCT. Since the statistical difference was not significant, the surgical stent can be considered to be an accurate guide tool for mini-implant placement in clinical use.

White Beam Slits and Pink Beam Slits for the Hard X-ray Nanoprobe Beamline at the Advanced Photon Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benson, C.; Jaski, Y.; Powers, T.

2007-01-19

A new type of slit has been designed for use in the hard x-ray nanoprobe beamline at the Advanced Photon Source (APS). The design incorporates monolithic GlidCop slit bodies mounted to commercially available x-y drive systems. Long, tapered apertures with adjacent water-cooling channels intercept the x-ray beam, removing the high heat load produced by two collinear APS undulators. The apertures are L-shaped and provide both horizontal and vertical slits. The beam-defining edges, positioned at the end of the tapered surfaces, consist of two sets of tungsten blades. These blades produce an exit beam with sharp corners and assure a cleanmore » cut-off for the white beam edges. The slit assembly is designed to allow overlap of the slit edges to stop the beam.The white beam slit design accommodates 3100 W of total power with a peak power density of 763 W/mm2. The pink beam slit design accommodates 400 W of total power with a peak power density of 180 W/mm2. Detailed thermal analyses were performed to verify the slits' accuracy under full beam loading. The new concept allows beamline operations to 180 mA with a simplified design approach.« less

White beam slits and pink beam slits for the hard x-ray nanoprobe beamline at the Advanced Photon Source.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benson, C.; Jaski, Y.; Maser, J.

2007-01-01

A new type of slit has been designed for use in the hard x-ray nanoprobe beamline at the Advanced Photon Source (APS). The design incorporates monolithic GlidCop slit bodies mounted to commercially available x-y drive systems. Long, tapered apertures with adjacent water-cooling channels intercept the x-ray beam, removing the high heat load produced by two collinear APS undulators. The apertures are L-shaped and provide both horizontal and vertical slits. The beam-defining edges, positioned at the end of the tapered surfaces, consist of two sets of tungsten blades. These blades produce an exit beam with sharp corners and assure a cleanmore » cut-off for the white beam edges. The slit assembly is designed to allow overlap of the slit edges to stop the beam. The white beam slit design accommodates 3100 W of total power with a peak power density of 763 W/mm2. The pink beam slit design accommodates 400 W of total power with a peak power density of 180 W/mm2. Detailed thermal analyses were performed to verify the slits accuracy under full beam loading. The new concept allows beamline operations to 180 mA with a simplified design approach.« less

Energy harvesting from controlled buckling of piezoelectric beams

NASA Astrophysics Data System (ADS)

Ansari, M. H.; Karami, M. Amin

2015-11-01

A piezoelectric vibration energy harvester is presented that can generate electricity from the weight of passing cars or crowds. The energy harvester consists of a piezoelectric beam, which buckles when the device is stepped on. The energy harvester can have a horizontal or vertical configuration. In the vertical (direct) configuration, the piezoelectric beam is vertical and directly sustains the weight of the vehicles or people. In the horizontal (indirect) configuration, the vertical weight is transferred to a horizontal axial force through a scissor-like mechanism. Buckling of the beam results in significant stresses and, thus, large power production. However, if the beam’s buckling is not controlled, the beam will fracture. To prevent this, the axial deformation is constrained to limit the deformations of the beam. In this paper, the energy harvester is analytically modeled. The considered piezoelectric beam is a general non-uniform beam. The natural frequencies, mode shapes, and the critical buckling force corresponding to each mode shape are calculated. The electro-mechanical coupling and the geometric nonlinearities are included in the model. The design criteria for the device are discussed. It is demonstrated that a device, realized with commonly used piezoelectric patches, can generate tens of milliwatts of power from passing car traffic. The proposed device could also be implemented in the sidewalks or integrated in shoe soles for energy generation. One of the key features of the device is its frequency up-conversion characteristics. The piezoelectric beam undergoes free vibrations each time the weight is applied to or removed from the energy harvester. The frequency of the free vibrations is orders of magnitude larger than the frequency of the load. The device is, thus, both efficient and insensitive to the frequency of the force excitations.

Wind measurement system

NASA Technical Reports Server (NTRS)

Cliff, W. C.; Huffaker, R. M.; Dahm, W. K.; Thomson, J. A. L.; Lawrence, T. R.; Krause, M. C.; Wilson, D. J. (Inventor)

1976-01-01

A system for remotely measuring vertical and horizontal winds present in discrete volumes of air at selected locations above the ground is described. A laser beam is optically focused in range by a telescope, and the output beam is conically scanned at an angle about a vertical axis. The backscatter, or reflected light, from the ambient particulates in a volume of air, the focal volume, is detected for shifts in wavelength, and from these, horizontal and vertical wind components are computed.

Vertical facial height and its correlation with facial width and depth: Three dimensional cone beam computed tomography evaluation based on dry skulls.

PubMed

Wang, Ming Feng; Otsuka, Takero; Akimoto, Susumu; Sato, Sadao

2013-01-01

The aim of the present study was to evaluate how vertical facial height correlates with mandibular plane angle, facial width and depth from a three dimensional (3D) viewing angle. In this study 3D cephalometric landmarks were identified and measurements from 43 randomly selected cone beam computed tomography (CBCT) images of dry skulls from the Weisbach collection of Vienna Natural History Museum were analyzed. Pearson correlation coefficients of facial height measurements and mandibular plane angle and the correlation coefficients of height-width and height-depth were calculated, respectively. The mandibular plane angle (MP-SN) significantly correlated with ramus height (Co-Go) and posterior facial height (PFH) but not with anterior lower face height (ALFH) or anterior total face height (ATFH). The ALFH and ATFH showed significant correlation with anterior cranial base length (S-N), whereas PFH showed significant correlation with the mandible (S-B) and maxilla (S-A) anteroposterior position. High or low mandibular plane angle might not necessarily be accompanied by long or short anterior face height, respectively. The PFH rather than AFH is assumed to play a key role in the vertical facial type whereas AFH seems to undergo relatively intrinsic growth.

Angle Control on the Optima HE/XE Ion Implanter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bell, Edward; Satoh, Shu

2008-11-03

The Optima HE/XE is the latest generation of high energy ion implanter from Axcelis, combining proven RF linear accelerator technology with new single wafer processing. The architecture of the implanter is designed to provide a parallel beam at the wafer plane over the full range of implant energies and beam currents. One of the advantages of this system is the ability to control both the horizontal and vertical implant angles for each implant. Included in the design is the ability to perform in situ measurements of the horizontal and vertical angles of the beam in real time. The method ofmore » the horizontal and vertical angle measurements is described in this paper.« less

Angle Performance on Optima XE

DOE Office of Scientific and Technical Information (OSTI.GOV)

David, Jonathan; Satoh, Shu

2011-01-07

Angle control on high energy implanters is important due to shrinking device dimensions, and sensitivity to channeling at high beam energies. On Optima XE, beam-to-wafer angles are controlled in both the horizontal and vertical directions. In the horizontal direction, the beam angle is measured through a series of narrow slits, and any angle adjustment is made by steering the beam with the corrector magnet. In the vertical direction, the beam angle is measured through a high aspect ratio mask, and any angle adjustment is made by slightly tilting the wafer platen during implant.Using a sensitive channeling condition, we were ablemore » to quantify the angle repeatability of Optima XE. By quantifying the sheet resistance sensitivity to both horizontal and vertical angle variation, the total angle variation was calculated as 0.04 deg. (1{sigma}). Implants were run over a five week period, with all of the wafers selected from a single boule, in order to control for any crystal cut variation.« less

Vertical and pitching resonance of train cars moving over a series of simple beams

NASA Astrophysics Data System (ADS)

Yang, Y. B.; Yau, J. D.

2015-02-01

The resonant response, including both vertical and pitching motions, of an undamped sprung mass unit moving over a series of simple beams is studied by a semi-analytical approach. For a sprung mass that is very small compared with the beam, we first simplify the sprung mass as a constant moving force and obtain the response of the beam in closed form. With this, we then solve for the response of the sprung mass passing over a series of simple beams, and validate the solution by an independent finite element analysis. To evaluate the pitching resonance, we consider the cases of a two-axle model and a coach model traveling over rough rails supported by a series of simple beams. The resonance of a train car is characterized by the fact that its response continues to build up, as it travels over more and more beams. For train cars with long axle intervals, the vertical acceleration induced by pitching resonance dominates the peak response of the train traveling over a series of simple beams. The present semi-analytical study allows us to grasp the key parameters involved in the primary/sub-resonant responses. Other phenomena of resonance are also discussed in the exemplar study.

Low profile, high load vertical rolling positioning stage

DOEpatents

Shu, Deming; Barraza, Juan

1996-01-01

A stage or support platform assembly for use in a synchrotron accurately positions equipment to be used in the beam line of the synchrotron. The support platform assembly includes an outer housing in which is disposed a lifting mechanism having a lifting platform or stage at its upper extremity on which the equipment is mounted. A worm gear assembly is located in the housing and is adapted to raise and lower a lifting shaft that is fixed to the lifting platform by an anti-binding connection. The lifting platform is moved vertically as the lifting shaft is moved vertically. The anti-binding connection prevents the shaft from rotating with respect to the platform, but does permit slight canting of the shaft with respect to the lifting platform so as to eliminate binding and wear due to possible tolerance mismatches. In order to ensure that the lifting mechanism does not move in a horizontal direction as it is moved vertically, at least three linear roller bearing assemblies are arranged around the outer-periphery of the lifting mechanism. One of the linear roller bearing assemblies can be adjusted so that the roller bearings apply a loading force against the lifting mechanism. Alternatively, a cam mechanism can be used to provide such a loading force.

Surface Relief of Mapping

NASA Astrophysics Data System (ADS)

Costa, Manuel F.; Almeida, Jose B.

1989-02-01

We will describe in this communication a noncont act method of measuring surface profile, it does not require any surface preparation, and it can be used with a very large range of surfaces from highly reflecting to non reflecting ones and as complex as textile surfaces. This method is reasonably immune to dispersion and diffraction, which usually make very difficult the application of non contact profilometry methods to a wide range of materials and situations, namely on quality control systems in industrial production lines. The method is based on the horizontal shift of the bright spot on a horizontal surface when this is illuminated with an oblique beam and moved vertically. in order to make the profilometry the sample is swept by an oblique light beam and the bright spot position is compared with a reference position. The bright spot must be as small as possible, particularly in very irregular surfaces; so the light beam diameter must be as small as possible and the incidence angle must not be too small. The sensivity of a system based on this method will be given, mostly, by the reception optical system.

Laser probe for measuring 2-D wave slope spectra of ocean capillary waves

NASA Technical Reports Server (NTRS)

Palm, C. S.; Anderson, R. C.; Reece, A. M.

1977-01-01

A laser-optical instrument for use in determining the two-dimensional wave-slope spectrum of ocean capillary waves is described. The instrument measures up to a 35-deg tip angle of the surface normal by measuring the position of a refracted laser beam directed vertically upward through a water surface. A telescope, a continuous two-dimensional Schottky barrier photodiode, and a pair of analog dividers render the signals independent of water height and insensitive to laser-beam intensity fluctuations. Calibration is performed entirely in the laboratory before field use. Sample records and wave-slope spectra are shown for one-dimensional wave-tank tests and for two-dimensional ocean tests. These are presented along with comparison spectra for calm and choppy water conditions. A mechanical wave follower was used to adjust the instrument position in the presence of large ocean swell and tides.

Experimental Investigation and Computer Modeling of Optical Switching in Distributed Bragg Reflector and Vertical Cavity Surface Emitting Laser Structures.

DTIC Science & Technology

1995-12-01

of a Molecular Beam Epitaxy (MBE) system prior to growing a Vertical Cavity Surface Emitting Laser ( VCSEL ). VCSEL bistability is discussed later in...addition, optical bistability 1 in the reflectivity of a DBR, as well as in the lasing power, wavelength, and beam divergence of a lasing VCSEL are...Spectral Reflectivity of AlGaAs/AlAs VCSEL Top DBR Mirror Cavity Bottom DBR Mirror Substrate Output Beam Resonance Pump Minimum Stop Band Figure 2. VCSEL

TH-AB-209-04: 3D Light Sheet Luminescence Imaging with Cherenkov Radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruza, P; Lin, H; Jarvis, L

Purpose: To recover a three-dimensional density distribution of luminescent molecular probes located several centimeters deep within a highly scattering tissue. Methods: We developed a novel sheet beam Cherenkov-excited luminescence scanned imaging (CELSI) methodology. The sample was irradiated by a horizontally oriented, vertically scanned 6 MV X-ray sheet beam (200mm × 5mm, 0.2mm vertical step) from a radiotherapy linear accelerator. The resulting Cherenkov light emission – and thus luminescent probe excitation – occurred exclusively along the irradiation plane due to a short diffusion path of secondary particles and Cherenkov photons. Cherenkov-excited luminescence was detected orthogonally to the sheet beam by gated,more » intensified charge coupled device camera. Analogously to light sheet microscopy, a series of luminescence images was taken for varied axial positions (depths) of the Cherenkov light sheet in sample. Knowledge of the excitation plane position allowed a 3D image stack deconvolution and depth-variant attenuation correction. The 3D image post-processing yielded a true spatial density distribution of luminescent molecules in highly scattering tissue. Results: We recovered a three-dimensional shape and position of 400 µL lesion-mimicking phantom tubes containing 25 µM solution of PtG4 molecular probe from 3 centimeter deep tissue-like media. The high sensitivity of CELSI also allowed resolving 100 micron capillaries of test solution. Functional information of partial oxygen pressure at the site of PtG4 molecular probe was recovered from luminescence lifetime CELSI. Finally, in-vivo sheet beam CELSI localized milimeter-sized PtG4-labelled tumor phantoms in multiple biological objects (hairless mice) from single scan. Conclusion: Presented sheet beam CELSI technique greatly extended the useful depth range of luminescence molecular imaging. More importantly, the light sheet microscopy approach was successfully adapted to CELSI, providing means to recover a completely attenuation-corrected 3D image of luminescent probe distribution. Gated CELSI acquisition yielded functional information of a spatially resolved oxygen concentration map of deep lying targets. This work was supported by NIH research grant R01CA109558 and R21EB017559, as well as by Pilot Grant Funds from the Norris Cotton Cancer Center.« less

Quantitative RHEED Studies of MBE Growth of 3-5 Compounds

DTIC Science & Technology

1991-06-03

Vertical - Cavity Surface - Emitting Laser Using Molecular Beam Epitaxial ...Growth of Vertical Cavity Surface - emitting Lasers Our work under this ARO contract on the control of MBE growth has enhanced our ability to grow...pattern about the surface structure of nearly perfect crystals prepared by Molecular Beam Epitaxy ( MBE ) and to use these techniques

Lithography with MeV Energy Ions for Biomedical Applications: Accelerator Considerations

NASA Astrophysics Data System (ADS)

Sangyuenyongpipat, S.; Whitlow, H. J.; Nakagawa, S. T.; Yoshida, E.

2009-03-01

MeV ion beam lithographies are very powerful techniques for 3D direct writing in positive or negtive photoresist materials. Nanometer-scale rough structures, or clear areas with straight vertical sidewalls as thin as a few 10's of nm in a resist of a few nm to 100 μm thickness can be made. These capabilities are particularly useful for lithography in cellular- and sub-cellular level biomedical research and technology applications. It can be used for tailor making special structures such as optical waveguides, biosensors, DNA sorters, spotting plates, systems for DNA, protein and cell separation, special cell-growth substrates and microfluidic lab-on-a-chip devices. Furthermore MeV ion beam lithography can be used for rapid prototyping, and also making master stamps and moulds for mass production by hot embossing and nanoimprint lithography. The accelerator requirements for three different high energy ion beam lithography techniques are overviewed. We consider the special requirements placed on the accelerator and how this is achieved for a commercial proton beam writing tool.

ACCELERATORS: Beam based alignment of the SSRF storage ring

NASA Astrophysics Data System (ADS)

Zhang, Man-Zhou; Li, Hao-Hu; Jiang, Bo-Cheng; Liu, Gui-Min; Li, De-Ming

2009-04-01

There are 140 beam position monitors (BPMs) in the Shanghai Synchrotron Radiation Facility (SSRF) storage ring used for measuring the closed orbit. As the BPM pickup electrodes are assembled directly on the vacuum chamber, it is important to calibrate the electrical center offset of the BPM to an adjacent quadrupole magnetic center. A beam based alignment (BBA) method which varies individual quadrupole magnet strength and observes its effects on the orbit is used to measure the BPM offsets in both the horizontal and vertical planes. It is a completely automated technique with various data processing methods. There are several parameters such as the strength change of the correctors and the quadrupoles which should be chosen carefully in real measurement. After several rounds of BBA measurement and closed orbit correction, these offsets are set to an accuracy better than 10 μm. In this paper we present the method of beam based calibration of BPMs, the experimental results of the SSRF storage ring, and the error analysis.

Ion shaking in the 200 MeV XLS-ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bozoki, E.; Kramer, S.L.

1992-12-31

It has been shown that ions, trapped inside the beam`s potential, can be removed by the clearing electrodes when the amplitude of the ion oscillation is increased by vertically shaking the ions. We will report on a similar experiment in the 200 Mev XLS ring. The design of the ion clearing system for the ring and the first results obtained, were already reported. In the present series of experiments, RF voltage was applied on a pair of vertical strip-lines. The frequency was scanned in the range of the ion (from H{sub 2} to CO{sub 2}) bounce frequencies in the ringmore » (1--10 MHz). The response of the beam size, vertical betatron tune and lifetime was studied.« less

Topographic analysis of maxillary premolars and molars and maxillary sinus using cone beam computed tomography.

PubMed

Yoshimine, Shin-Ichiro; Nishihara, Kazuhide; Nozoe, Etsuro; Yoshimine, Masako; Nakamura, Norifumi

2012-12-01

This study evaluated the anatomical characteristics of the maxillary premolars and molars and the maxillary sinus using cone beam computed tomography (CBCT) for dental implant treatment. Ten linear items and 1 angular item on 30 sites in 30 patients were measured on 3-dimensional computed tomography images using CBCT. The vertical relationship between the maxillary sinus and the maxillary molars was classified into 5 categories. The horizontal thickness of the buccal alveolar bone was thinnest on the maxillary first premolars, and the horizontal thickness of the palatal alveolar bone was thickest on the maxillary second molars. Type II was most common on the maxillary first molars. The internal angle at the maxillary premolars was significantly greater than that at the maxillary molars. The internal angle and vertical distance between the apex of the roots and the maxillary sinus floor showed a positive correlation on the maxillary first premolars (P = 0.003). For the selection of an appropriate approach on dental implant treatment, the evaluation of maxillary premolars and molars using of CBCT can be recommended.

The echolocation transmission beam of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis).

PubMed

Fang, Liang; Wu, Yuping; Wang, Kexiong; Pine, Matthew K; Wang, Ding; Li, Songhai

2017-08-01

While the transmission beam of odontocetes has been described in a number of studies, the majority of them that have measured the transmission beam in two dimensions were focused on captive animals. Within the current study, a dedicated cross hydrophone array with nine elements was used to investigate the echolocation transmission beam of free-ranging Indo-Pacific humpback dolphins. A total of 265 on-axis clicks were analyzed, from which the apparent peak to peak source levels ranged between 168 to 207 dB (mean 184.5 dB ± 6.6 dB). The 3-dB beam width along the horizontal and vertical plane was 9.6° and 7.4°, respectively. Measured separately, the directivity index of the horizontal and vertical plane was 12.6 and 13.5 dB, respectively, and the overall directivity index (both planes combined) was 29.5 dB. The beam shape was slightly asymmetrical along the horizontal and vertical axis. Compared to other species, the characteristics of the transmitting beam of Indo-Pacific humpback dolphins were relatively close to the bottlenose dolphin (Tursiops truncatus), likely due to the similarity in the peak frequency and waveform of echolocation clicks and comparable body sizes of the two species.

Integrated Lloyd's mirror on planar waveguide facet as a spectrometer.

PubMed

Morand, Alain; Benech, Pierre; Gri, Martine

2017-12-10

A low-cost and simple Fourier transform spectrometer based on the Lloyd's mirror configuration is proposed in order to have a very stable interferogram. A planar waveguide coupled to a fiber injection is used to spatially disperse the optical beam. A second beam superposed to the previous one is obtained by a total reflection of the incident beam on a vertical glass face integrated in the chip by dicing with a specific circular precision saw. The interferogram at the waveguide output is imaged on a near-infrared camera with an objective lens. The contrast and the fringe period are thus dependent on the type and the fiber position and can be optimized to the pixel size and the length of the camera. Spectral resolution close to λ/Δλ=80 is reached with a camera with 320 pixels of 25 μm width in a wavelength range from O to L bands.

SU-D-BRB-02: Investigations of Secondary Ion Distributions in Carbon Ion Therapy Using the Timepix Detector.

PubMed

Gwosch, K; Hartmann, B; Jakubek, J; Granja, C; Soukup, P; Jaekel, O; Martisikova, M

2012-06-01

Due to the high conformity of carbon ion therapy, unpredictable changes in the patient's geometry or deviations from the planned beam properties can result in changes of the dose distribution. PET has been used successfully to monitor the actual dose distribution in the patient. However, it suffers from biological washout processes and low detection efficiency. The purpose of this contribution is to investigate the potential of beam monitoring by detection of prompt secondary ions emerging from a homogeneous phantom, simulating a patient's head. Measurements were performed at the Heidelberg Ion-Beam Therapy Center (Germany) using a carbon ion pencil beam irradiated on a cylindrical PMMA phantom (16cm diameter). For registration of the secondary ions, the Timepix detector was used. This pixelated silicon detector allows position-resolved measurements of individual ions (256×256 pixels, 55μm pitch). To track the secondary ions we used several parallel detectors (3D voxel detector). For monitoring of the beam in the phantom, we analyzed the directional distribution of the registered ions. This distribution shows a clear dependence on the initial beam energy, width and position. Detectable were range differences of 1.7mm, as well as vertical and horizontal shifts of the beam position by 1mm. To estimate the clinical potential of this method, we measured the yield of secondary ions emerging from the phantom for a beam energy of 226MeV/u. The differential distribution of secondary ions as a function of the angle from the beam axis for angles between 0 and 90° will be presented. In this setup the total yield in the forward hemisphere was found to be in the order of 10 -1 secondary ions per primary carbon ion. The presented measurements show that tracking of secondary ions provides a promising method for non-invasive monitoring of ion beam parameters for clinical relevant carbon ion fluences. Research with the pixel detectors was carried out in frame of the Medipix Collaboration. © 2012 American Association of Physicists in Medicine.

Anthropometry and Range of Motion of the Encumbered Soldier

DTIC Science & Technology

2017-03-01

this location and positions the anthropometer blade just behind the landmark to obtain the vertical measurement. The measurer is careful not to...evenly on both feet. The measurer stands in front of the TP and lines up the blades of the beam caliper at the level of Chest Point Anterior. The...to maintain contact between the tape and the skin. The tape measure spans the hollows between the shoulder blades and chest. The measurement is

First Experiments with the Polarized Internal Gas Target (PIT) at ANKE/COSY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engels, R.; Lorentz, B.; Prasuhn, D.

2009-08-04

For future few-nucleon interaction studies with polarized beams and targets at COSY-Juelich, a polarized internal storage-cell gas target was implemented at the magnet spectrometer ANKE. First commissioning of the polarized Atomic Beam Source (ABS) at ANKE was carried out and some improvements of the system have been done. Storage-cell tests to determine the COSY beam dimensions have been performed. Electron cooling combined with stacking and stochastic cooling have been studied. Experiments with N{sub 2} gas in the storage cell to simulate the background produced by beam interaction with the aluminum cell walls were performed to investigate the beam heating bymore » the target gas. The analysis of the d-vectorp-vector->dp and d-vectorp-vector->(dp{sub sp})pi{sup 0} reactions showed that events from different positions of the extended target can be clearly identified in the ANKE detector system. The polarization of the atomic beam of the ABS, positioned close to the strong dipole magnet D2 of ANKE, was tuned with a Lamb-shift polarimeter (LSP) beneath the target chamber. With use of the known analyzing powers of the quasi-free np->dpi{sup 0} reaction, the polarization in the storage cell was measured to be Q{sub y} = 0.79+-0.07 in the vertical stray field of the D2 magnet acting as a holding field. The target thickness achieved was 2x10{sup 13} atoms/cm{sup 2} for one hyperfine state populated in the ABS beam only. With a COSY beam intensity of 6x10{sup 9} stored polarized deuterons in the ring, the luminosity for double polarized experiments was 1x10{sup 29} cm{sup -2} s{sup -1}.« less

New x-ray parallel beam facility XPBF 2.0 for the characterization of silicon pore optics

NASA Astrophysics Data System (ADS)

Krumrey, Michael; Müller, Peter; Cibik, Levent; Collon, Max; Barrière, Nicolas; Vacanti, Giuseppe; Bavdaz, Marcos; Wille, Eric

2016-07-01

A new X-ray parallel beam facility (XPBF 2.0) has been installed in the laboratory of the Physikalisch-Technische Bundesanstalt at the synchrotron radiation facility BESSY II in Berlin to characterize silicon pore optics (SPOs) for the future X-ray observatory ATHENA. As the existing XPBF which is operated since 2005, the new beamline provides a pencil beam of very low divergence, a vacuum chamber with a hexapod system for accurate positioning of the SPO to be investigated, and a vertically movable CCD-based camera system to register the direct and the reflected beam. In contrast to the existing beamline, a multilayer-coated toroidal mirror is used for beam monochromatization at 1.6 keV and collimation, enabling the use of beam sizes between about 100 μm and at least 5 mm. Thus the quality of individual pores as well as the focusing properties of large groups of pores can be investigated. The new beamline also features increased travel ranges for the hexapod to cope with larger SPOs and a sample to detector distance of 12 m corresponding to the envisaged focal length of ATHENA.

Bulk vertical micromachining of single-crystal sapphire using inductively coupled plasma etching for x-ray resonant cavities

NASA Astrophysics Data System (ADS)

Chen, P.-C.; Lin, P.-T.; Mikolas, D. G.; Tsai, Y.-W.; Wang, Y.-L.; Fu, C.-C.; Chang, S.-L.

2015-01-01

To provide coherent x-ray sources for probing the dynamic structures of solid or liquid biological substances on the picosecond timescale, a high-aspect-ratio x-ray resonator cavity etched from a single crystal substrate with a nearly vertical sidewall structure is required. Although high-aspect-ratio resonator cavities have been produced in silicon, they suffer from unwanted multiple beam effects. However, this problem can be avoided by using the reduced symmetry of single-crystal sapphire in which x-ray cavities may produce a highly monochromatic transmitted x-ray beam. In this study, we performed nominal 100 µm deep etching and vertical sidewall profiles in single crystal sapphire using inductively coupled plasma (ICP) etching. The large depth is required to intercept a useful fraction of a stopped-down x-ray beam, as well as for beam clearance. An electroplated Ni hard mask was patterned using KMPR 1050 photoresist and contact lithography. The quality and performance of the x-ray cavity depended upon the uniformity of the cavity gap and therefore verticality of the fabricated vertical sidewall. To our knowledge, this is the first report of such deep, vertical etching of single-crystal sapphire. A gas mixture of Cl2/BCl3/Ar was used to etch the sapphire with process variables including BCl3 flow ratio and bias power. By etching for 540 min under optimal conditions, we obtained an x-ray resonant cavity with a depth of 95 µm, width of ~30 µm, gap of ~115 µm and sidewall profile internal angle of 89.5°. The results show that the etching parameters affected the quality of the vertical sidewall, which is essential for good x-ray resonant cavities.

Comparison of Online 6 Degree-of-Freedom Image Registration of Varian TrueBeam Cone-Beam CT and BrainLab ExacTrac X-Ray for Intracranial Radiosurgery.

PubMed

Li, Jun; Shi, Wenyin; Andrews, David; Werner-Wasik, Maria; Lu, Bo; Yu, Yan; Dicker, Adam; Liu, Haisong

2017-06-01

The study was aimed to compare online 6 degree-of-freedom image registrations of TrueBeam cone-beam computed tomography and BrainLab ExacTrac X-ray imaging systems for intracranial radiosurgery. Phantom and patient studies were performed on a Varian TrueBeam STx linear accelerator (version 2.5), which is integrated with a BrainLab ExacTrac imaging system (version 6.1.1). The phantom study was based on a Rando head phantom and was designed to evaluate isocenter location dependence of the image registrations. Ten isocenters at various locations representing clinical treatment sites were selected in the phantom. Cone-beam computed tomography and ExacTrac X-ray images were taken when the phantom was located at each isocenter. The patient study included 34 patients. Cone-beam computed tomography and ExacTrac X-ray images were taken at each patient's treatment position. The 6 degree-of-freedom image registrations were performed on cone-beam computed tomography and ExacTrac, and residual errors calculated from cone-beam computed tomography and ExacTrac were compared. In the phantom study, the average residual error differences (absolute values) between cone-beam computed tomography and ExacTrac image registrations were 0.17 ± 0.11 mm, 0.36 ± 0.20 mm, and 0.25 ± 0.11 mm in the vertical, longitudinal, and lateral directions, respectively. The average residual error differences in the rotation, roll, and pitch were 0.34° ± 0.08°, 0.13° ± 0.09°, and 0.12° ± 0.10°, respectively. In the patient study, the average residual error differences in the vertical, longitudinal, and lateral directions were 0.20 ± 0.16 mm, 0.30 ± 0.18 mm, 0.21 ± 0.18 mm, respectively. The average residual error differences in the rotation, roll, and pitch were 0.40°± 0.16°, 0.17° ± 0.13°, and 0.20° ± 0.14°, respectively. Overall, the average residual error differences were <0.4 mm in the translational directions and <0.5° in the rotational directions. ExacTrac X-ray image registration is comparable to TrueBeam cone-beam computed tomography image registration in intracranial treatments.

Vertical-cavity surface-emitting lasers - Design, growth, fabrication, characterization

NASA Astrophysics Data System (ADS)

Jewell, Jack L.; Lee, Y. H.; Harbison, J. P.; Scherer, A.; Florez, L. T.

1991-06-01

The authors have designed, fabricated, and tested vertical-cavity surface-emitting lasers (VCSEL) with diameters ranging from 0.5 microns to above 50 microns. Design issues, molecular beam epitaxial growth, fabrication, and lasing characteristics are discussed. The topics considered in fabrication of VCSELs are microlaser geometries; ion implementation and masks; ion beam etching; packaging and arrays; and ultrasmall devices.

SPEAR — ToF neutron reflectometer at the Los Alamos Neutron Science Center

NASA Astrophysics Data System (ADS)

Dubey, M.; Jablin, M. S.; Wang, P.; Mocko, M.; Majewski, J.

2011-11-01

This article discusses the Surface ProfilE Analysis Reflectometer (SPEAR), a vertical scattering geometry time-of-flight reflectometer, at the Los Alamos National Laboratory Lujan Neutron Scattering Center. SPEAR occupies flight path 9 and receives spallation neutrons from a polychromatic, pulsed (20Hz) source that pass through a liquid-hydrogen moderator at 20K coupled with a Be filter to shift their energy spectrum. The spallation neutrons are generated by bombarding a tungsten target with 800MeV protons obtained from an accelerator. The process produces an integrated neutron flux of ˜ 3.4×106 cm-2 s-1 at a proton current of 100 μA. SPEAR employs choppers and frame overlap mirrors to obtain a neutron wavelength range of 4.5-16 Å. SPEAR uses a single 200mm long 3He linear position-sensitive detector with ˜ 2 mm FWHM resolution for simultaneous studies of both specular and off-specular scattering. SPEAR's moderated neutrons are collimated into a beam which impinges from above upon a level sample with an average angle of 0.9° to the horizontal, to facilitate air-liquid interface studies. In the vertical direction, the beam converges at the sample position. The neutrons can be further collimated to the desired divergence by finely slitting the beam using a set of two 10B4C slit packages. The instrument is ideally suited to study organic and inorganic thin films with total thicknesses between 5 and 3000 Å in a variety of environments. Specifically designed sample chambers available at the instrument provide the opportunity to study biological systems at the solid-liquid interface. SPEAR's unique experimental capabilities are demonstrated by specific examples in this article. Finally, an outlook for SPEAR and perspectives on future instrumentation are discussed.

Experiments to trap dust particles by a wire simulating an electron beam

NASA Astrophysics Data System (ADS)

Saeki, Hiroshi; Momose, Takashi; Ishimaru, Hajime

1991-11-01

Motion of trapped dust particles has been previously analyzed using high-energy bremsstrahlung data obtained during dust trapping in the TRISTAN accumulation ring. Because it is difficult to observe the actual motions of dust particles trapped in an electron beam due to the strong synchrotron light background, we carried out experiments to trap sample dust particles with a Cu wire simulating an electron beam. A negative potential was slowly applied to the wire using a high voltage dc power supply. Motions of dust particles trapped by the wire were recorded with a video camera system. In an experiment using a Cu wire (1.5 mm in diameter) with no magnetic field, the charged dust particle made vertical oscillation about the wire. In another experiment using the same wire but with a vertical magnetic field (0.135 T) simulating a bending magnetic field, both vertical and horizontal oscillating motions perpendicular to the wire were observed. Furthermore, it was found that the dust particle moved in the longitudinal direction of the wire in the bending magnetic field. Therefore, it is expected that charged dust particles trapped by the electric field of the electron beam oscillate vertically where there is no magnetic field in the TRISTAN accumulation ring. It is also expected that trapped dust particles where there is a bending magnetic field oscillate horizontally and vertically as the particle drifts in a longitudinal direction along the ring.

Use of cone beam computed tomography to assess significant imaging findings related to mandibular third molar impaction.

PubMed

Matzen, Louise Hauge; Schropp, Lars; Spin-Neto, Rubens; Wenzel, Ann

2017-11-01

The aim of the study was to identify risk factors for pathoses related to mandibular third molars observed in cone beam computed tomography. Cone beam computed tomography volumes of 410 mandibular third molars were assessed by 3 observers, according to the angulation and position of the third molar in relation to the second molar. In addition, pathoses (marginal bone loss, resorption of the second molar, increased follicular space and lingual bone perforation) were assessed. Logistic regression analyses were used to test whether the angulation and position of the third molar were risk factors for pathoses. On average, 41% of second molars had resorption; mesioangulated (odds ratio [OR] 11-107; P < .001) and horizontally positioned (OR 13-120; P < .001) third molars located cervically at the second molar (OR 2-3; P < .027) significantly increased the risk. On average, 49% of second molars had marginal bone loss; mesioangulated (OR 16-85; P < .001) and horizontally positioned (OR 61-573; P < .001) third molars increased the risk. For the third molar, an increased follicular space was seen in 25% of cases; distal (OR 5-9; P < .001) and vertical positions (OR 5; P < .002) increased the risk. Lingual bone perforation was not related to a specific angulation. Specific angulations of the mandibular third molar are risk factors for marginal bone loss and resorption of the second molar. Copyright © 2017 Elsevier Inc. All rights reserved.

Planar microlens with front-face angle: design, fabrication, and characterization

NASA Astrophysics Data System (ADS)

Al Hafiz, Md. Abdullah; Michael, Aron; Kwok, Chee-Yee

2016-07-01

This paper studies the effect of microlens front-face angle on the performance of an optical system consisting of a planar-graded refractive index (GRIN) lens pair facing each other separated by a free-space region. The planar silica microlens pairs are designed to facilitate low-loss optical signal propagation in the free-space region between the opposing optical waveguides. The planar lens is fabricated from a 38-μm-thick fluorine-doped silica layer on a silicon substrate. It has a parabolic refractive index profile in the vertical direction, which is achieved by controlled fluorine incorporation in the silica film to collimate the optical beam in the vertical direction. Horizontal beam collimation is achieved by incorporating a horizontal curvature at the front face of the lens defined by deep oxide etch. A generalized 3×3 ABCDGH transformation matrix method has been derived to compute the coupling efficiency of such microlens pairs to take front-face angles that may be present due to fabrication variations or limitations and possible input/output optical fiber offset/tilt into considerations. Pairs of such planar GRIN lens with various free-space propagation distances between them ranging from 75 to 2500 μm and with front-face angles of 1.5 deg, 2 deg, and 4 deg have been fabricated and characterized. Beam propagation method simulations have been carried out to substantiate the theoretical and experimental results. The results indicate that the optical loss is reasonably low up to 1.5 deg of front-face angles and increases significantly with further increase in the front-face angle. Analysis shows that for a given system with specific microlens front-face angle, the optical loss can be significantly reduced by properly compensating the vertical position of the input and output fibers.

The accuracy of image-guided navigation for maxillary positioning in bimaxillary surgery.

PubMed

Sun, Yi; Luebbers, Heinz-Theo; Agbaje, Jimoh Olubanwo; Lambrichts, Ivo; Politis, Constantinus

2014-05-01

The aim of our study was to evaluate the accuracy of image-guided maxillary positioning in sagittal, vertical, and mediolateral direction. Between May 2011 and July 2012, 17 patients (11 males, 6 females) underwent bimaxillary surgery with the use of intraoperative surgical navigation. During Le Fort I osteotomy, the Kolibri navigation system was used to measure movement of the maxilla at the edge of the upper central upper incisor in sagittal (buccal surface), vertical (incisor edge), and mediolateral (dental midline) direction. Six weeks after surgery, a postoperative CBCT scan was taken and registered to the preoperative cone-beam computed tomography scan to identify the actual surgical movement of the maxilla. Student 2-tailed paired t test was used to evaluate differences between the measured result from navigation system and actual surgical movement of the maxilla, which were 0.44 ± 0.35 mm (P = 0.82) in the sagittal, 0.50 ± 0.35 mm (P = 0.85) in the vertical, and 0.56 ± 0.36 mm (P = 0.81) in the mediolateral direction. Our finding demonstrates that intraoperative computer navigation is a promising tool for measuring the surgical change of the maxilla in bimaxillary surgery.

Improved power and efficiency for tapered lasers with optimized photonic crystal structures

NASA Astrophysics Data System (ADS)

Ma, Xiaolong; Qu, Hongwei; Zhao, Shaoyu; Zhou, Xuyan; Lin, Yuzhe; Zheng, Wanhua

2017-10-01

High power and high beam quality laser sources are required in numerous applications such as nonlinear frequency conversion, optical pumping of solid-state and fiber lasers, material processing and others. Tapered lasers can provide a high output power while keeping a high beam quality. However, the conventional tapered lasers suffer from a large vertical beam divergence. We have demonstrated 2-mm long tapered lasers with photonic crystal structures. A high beam quality and a narrow vertical divergence are achieved. In this paper, we optimized the photonic crystal structure and fabricated a 4-mm long tapered laser to further increase the output power and the wall-plug efficiency. Compared with our precious wafer, the optimized structure has a lower doping level to reduce the internal loss. The period of the photonic crystal structure and the thickness of the upper cladding are also reduced. The device has a 1-mm long ridge-waveguide section and a 3-mm long tapered section. The taper angle is 4°. An output power of 7.3 W is achieved with a peak wall-plug efficiency of 46% in continuous-wave mode. The threshold current is around 500 mA and the slope efficiency is 0.93 W/A. In pulsed mode, the output power is 15.6 W and the maximum wall-plug efficiency is 48.1%. The far-field divergence with full width at half maximum is 6.3° for the lateral direction at 3 A. The vertical far-field beam divergence is around 11° at different injection levels. High beam qualities are demonstrated by beam quality factor M2 of 1.52 for the lateral direction and 1.54 for the vertical direction.

Ultrafast Beam Switching Using Coupled VCSELs

NASA Technical Reports Server (NTRS)

Ning, Cun-Zheng; Goorjian, Peter

2001-01-01

We propose a new approach to performing ultrafast beam switching using two coupled Vertical-Cavity Surface-Emitting Lasers (VCSELs). The strategy is demonstrated by numerical simulation, showing a beam switching of 10 deg at 42 GHz.

980 nm tapered lasers with photonic crystal structure for low vertical divergence

NASA Astrophysics Data System (ADS)

Ma, Xiaolong; Qu, Hongwei; Zhao, Pengchao; Liu, Yun; Zheng, Wanhua

2016-10-01

High power tapered lasers with nearly diffraction-limited beam quality have attracted much attention in numerous applications such as nonlinear frequency conversion, optical pumping of solid-state and fiber lasers, medical treatment and others. However, the large vertical divergence of conventional tapered lasers is a disadvantage, which makes beam shaping difficult and expensive in applications. Diode lasers with photonic crystal structure can achieve a large mode size and a narrow vertical divergence. In this paper, we present tapered lasers with photonic crystal structure emitting at 980 nm. The epitaxial layer is grown using metal organic chemical vapor deposition. The device has a total cavity length of 2 mm, which consists of a 400-um long ridge-waveguide section and a 1600-um long tapered section. The taper angle is 4°. An output power of 3.3 W is achieved with a peak conversion efficiency of 35% in pulsed mode. The threshold current is 240 mA and the slope efficiency is 0.78 W/A. In continuous wave mode, the output power is 2.87 W, which is limited by a suddenly failure resulting from catastrophic optical mirror damage. The far field divergences with full width at half maximum are 12.3° in the vertical direction and 2.9° in the lateral direction at 0.5 A. At high injection level the vertical divergence doesn't exceed 16°. Beam quality factor M2 is measured based on second moment definition in CW mode. High beam quality is demonstrated by M2 value of less than 2 in both vertical and lateral directions.

APPARATUS FOR VACUUM DEPOSITION OF METALS

DOEpatents

Milleron, N.

1962-03-13

An apparatus and a method are described for continuous vacuum deposition of metals for metallic coatings, for ultra-high vacuum work, for purification of metals, for maintaining high-density electron currents, and for other uses. The apparatus comprises an externally cooled feeder tube extending into a container and adapted to feed metal wire or strip so that it emerges in a generally vertical position therein. The tube also provides shielding from the heat produced by an electron beam therein focused to impinge from a vertical direction upon the tip of the emerging wire. By proper control of the wire feed, coolant feed, and electron beam intensity, a molten ball of metal forms upon the emerging tip and remains self-supported thereon by the interaction of various forces. The metal is vaporized and travels in a line of sight direction, while additional wire is fed from the tube, so that the size of the molten ball remains constant. In the preferred embodiments, the wire is selected from a number of gettering metals and is degassed by electrical resistance in an adjacent chamber which is also partially evacuated. The wire is then fed through the feed tube into the electron beam and vaporizes and adsorbs gases to provide pumping action while being continuously deposited upon surfaces within the chamber. Ion pump electrodes may also be provided within line of sight of the vaporizing metal source to enhance the pumping action. (AEC)

Assessment of morphological and anatomical characteristics of mental foramen using cone beam computed tomography.

PubMed

Goyushov, Samir; Tözüm, Melek Didem; Tözüm, Tolga Fikret

2018-05-25

To determine the shape, position, vertical height, surrounding bone characteristics, and opening angle of mental foramen (MF) using dental cone beam computed tomography (CBCT). A retrospective study was performed on 663 patients. CBCT records analyzed for the shape, position, and surrounding bone measurements of the MF using Simplant 3D software (Hasselt, Belgium). Opening angle of MF was also assessed. Kruskal-Wallis and Mann-Whitney U tests were employed to test significant differences between parameters, genders and ages. All mental foramina were visualized. Regarding location, 49.2% of the MFs were located between first and second premolars, 7.7 distal and 39.7% coincident to the apex of the mandibular second premolar. The mean MF opening angle was 45.4° on the right side, and 45.9° on the left. There were no statistically differences between gender groups with regard to the opening angle degrees. This study may provide useful information about variations in the position, shape and size, angle of mental foramen, which may help the practitioners to perform safer mental nerve blocks and surgical procedures.

Three-dimensional analysis of maxillary stability after Le Fort I osteotomy using hydroxyapatite/poly-L-lactide plate.

PubMed

Park, Jung-Hyun; Kim, Minkyu; Kim, Sang Yoon; Jung, Hwi-Dong; Jung, Young-Soo

2016-04-01

To evaluate three-dimensional change in maxillary position using biodegradable plates. A total of 53 patients who underwent orthognathic surgery using biodegradable plates were analyzed retrospectively. The position of maxilla was measured three-dimensionally using cone beam computed tomography data at preoperative (T0), 1-month postoperative (T1), and 1-year postoperative (T2) time points. Changes in the maxilla 1 year after the operation (T2-T1) were analyzed to demonstrate postoperative stability. The correlation between postoperative relapse (T2-T1) and surgical movement (T1-T0) of the maxilla was investigated. At 1-year postoperatively, no significant changes in maxillary position were noted in the antero-posterior and transverse dimensions. The anterior maxillary position in the vertical dimension also showed no significant changes, but the posterior maxillary position (posterior nasal spine, greater palatine foramen) showed a 0- to 2.98-mm relapse at 1-year postoperatively. The posterior maxilla tended to relapse inferiorly when the amount of surgical upward movement was greater than 3-3.5 mm and to relapse superiorly when the amount of surgical upward movement was less than 3-3.5 mm. For all patients, no postoperative complications in the osteofixated maxilla were observed during the follow-up period. Maxilla fixed with biodegradable plates was stable in the antero-posterior and transverse and the vertical (anterior maxilla) dimensions. Posterior maxillary vertical relapse was clinically acceptable, but relapse patterns that relate to the amount of surgical upward movement should be considered for surgical treatment planning. Copyright © 2016. Published by Elsevier Ltd.

Synchrotron radiation external beam rotational radiotherapy of breast cancer: proof of principle.

PubMed

Di Lillo, Francesca; Mettivier, Giovanni; Castriconi, Roberta; Sarno, Antonio; Stevenson, Andrew W; Hall, Chris J; Häusermann, Daniel; Russo, Paolo

2018-05-01

The principle of rotational summation of the absorbed dose for breast cancer treatment with orthovoltage X-ray beams was proposed by J. Boone in 2012. Here, use of X-ray synchrotron radiation for image guided external beam rotational radiotherapy treatment of breast cancer is proposed. Tumor irradiation occurs with the patient in the prone position hosted on a rotating bed, with her breast hanging from a hole in the bed, which rotates around a vertical axis passing through the tumor site. Horizontal collimation of the X-ray beam provides for whole breast or partial breast irradiation, while vertical translation of the bed and successive rotations allow for irradiation of the full tumor volume, with dose rates which permit also hypofractionated treatments. In this work, which follows a previous preliminary report, results are shown of a full series of measurements on polyethylene and acrylic cylindrical phantoms carried out at the Australian Synchrotron, confirmed by Geant4 Monte Carlo simulations, intended to demonstrate the proof of principle of the technique. Dose measurements were carried out with calibrated ion chambers, radiochromic films and thermoluminescence dosimeters. The photon energy investigated was 60 keV. Image guidance may occur with the transmitted beam for contrast-enhanced breast computed tomography. For a horizontal beam collimation of 1.5 cm and rotation around the central axis of a 14 cm-diameter polyethylene phantom, a periphery-to-center dose ratio of 14% was measured. The simulations showed that under the same conditions the dose ratio decreases with increasing photon energy down to 10% at 175 keV. These values are comparable with those achievable with conventional megavoltage radiotherapy of breast cancer with a medical linear accelerator. Dose painting was demonstrated with two off-center `cancer foci' with 1.3 Gy and 0.6 Gy target doses. The use of a radiosensitizing agent for dose enhancement is foreseen.

Solving nonlinear equilibrium equations of deformable systems by method of embedded polygons

NASA Astrophysics Data System (ADS)

Razdolsky, A. G.

2017-09-01

Solving of nonlinear algebraic equations is an obligatory stage of studying the equilibrium paths of nonlinear deformable systems. The iterative method for solving a system of nonlinear algebraic equations stated in an explicit or implicit form is developed in the present work. The method consists of constructing a sequence of polygons in Euclidean space that converge into a single point that displays the solution of the system. Polygon vertices are determined on the assumption that individual equations of the system are independent from each other and each of them is a function of only one variable. Initial positions of vertices for each subsequent polygon are specified at the midpoints of certain straight segments determined at the previous iteration. The present algorithm is applied for analytical investigation of the behavior of biaxially compressed nonlinear-elastic beam-column with an open thin-walled cross-section. Numerical examples are made for the I-beam-column on the assumption that its material follows a bilinear stress-strain diagram. A computer program based on the shooting method is developed for solving the problem. The method is reduced to numerical integration of a system of differential equations and to the solution of a system of nonlinear algebraic equations between the boundary values of displacements at the ends of the beam-column. A stress distribution at the beam-column cross-sections is determined by subdividing the cross-section area into many small cells. The equilibrium path for the twisting angle and the lateral displacements tend to the stationary point when the load is increased. Configuration of the path curves reveals that the ultimate load is reached shortly once the maximal normal stresses at the beam-column fall outside the limit of the elastic region. The beam-column has a unique equilibrium state for each value of the load, that is, there are no equilibrium states once the maximum load is reached.

Vertical dynamic deflection measurement in concrete beams with the Microsoft Kinect.

PubMed

Qi, Xiaojuan; Lichti, Derek; El-Badry, Mamdouh; Chow, Jacky; Ang, Kathleen

2014-02-19

The Microsoft Kinect is arguably the most popular RGB-D camera currently on the market, partially due to its low cost. It offers many advantages for the measurement of dynamic phenomena since it can directly measure three-dimensional coordinates of objects at video frame rate using a single sensor. This paper presents the results of an investigation into the development of a Microsoft Kinect-based system for measuring the deflection of reinforced concrete beams subjected to cyclic loads. New segmentation methods for object extraction from the Kinect's depth imagery and vertical displacement reconstruction algorithms have been developed and implemented to reconstruct the time-dependent displacement of concrete beams tested in laboratory conditions. The results demonstrate that the amplitude and frequency of the vertical displacements can be reconstructed with submillimetre and milliHz-level precision and accuracy, respectively.

Vertical Dynamic Deflection Measurement in Concrete Beams with the Microsoft Kinect

PubMed Central

Qi, Xiaojuan; Lichti, Derek; El-Badry, Mamdouh; Chow, Jacky; Ang, Kathleen

2014-01-01

The Microsoft Kinect is arguably the most popular RGB-D camera currently on the market, partially due to its low cost. It offers many advantages for the measurement of dynamic phenomena since it can directly measure three-dimensional coordinates of objects at video frame rate using a single sensor. This paper presents the results of an investigation into the development of a Microsoft Kinect-based system for measuring the deflection of reinforced concrete beams subjected to cyclic loads. New segmentation methods for object extraction from the Kinect's depth imagery and vertical displacement reconstruction algorithms have been developed and implemented to reconstruct the time-dependent displacement of concrete beams tested in laboratory conditions. The results demonstrate that the amplitude and frequency of the vertical displacements can be reconstructed with submillimetre and milliHz-level precision and accuracy, respectively. PMID:24556668

Monolithic integration of multiple wavelength vertical-cavity surface-emitting lasers by mask molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Saito, Hideaki; Ogura, Ichiro; Sugimoto, Yoshimasa; Kasahara, Kenichi

1995-05-01

The monolithic incorporation and performance of vertical-cavity surface-emitting lasers (VCSELs) emitting at two distinct wavelengths, which were suited for application to wavelength division multiplexing (WDM) systems were reported. The monolithic integration of two-wavelength VCSEL arrays was achieved by using mask molecular beam epitaxy. This method can generate arrays that have the desired integration area size and wavelength separation.

Knowledge and application of correct car seat head restraint usage among chiropractic college interns: a cross-sectional study.

PubMed

Taylor, John Am; Burke, Jeanmarie; Gavencak, John; Panwar, Pervinder

2005-03-01

Cervical spine injuries sustained in rear-end crashes cost at least $7 billion in insurance claims annually in the United States alone. When positioned correctly, head restraint systems have been proven effective in reducing the risk of whiplash associated disorders. Chiropractors should be knowledgeable about the correct use of head restraint systems to educate their patients and thereby prevent or minimize such injuries. The primary objective of this study was to determine the prevalence of correct positioning of car seat head restraints among the interns at our institution. The secondary objective was to determine the same chiropractic interns' knowledge of the correct positioning of car seat head restraints. It was hypothesized that 100 percent of interns would have their head restraint correctly positioned within an acceptable range and that all interns would possess the knowledge to instruct patients in the correct positioning of head restraints. Cross-sectional study of a convenient sample of 30 chiropractic interns from one institution. Interns driving into the parking lot of our health center were asked to volunteer to have measurements taken and to complete a survey. Vertical and horizontal positions of the head restraint were measured using a beam compass. A survey was administered to determine knowledge of correct head restraint position. The results were recorded, entered into a spreadsheet, and analyzed. 13.3 percent of subjects knew the recommended vertical distance and only 20 percent of subjects knew the recommended horizontal distance. Chi Square analyses substantiated that the majority of subjects were unaware of guidelines set forth by the National Highway Traffic Safety Administration (NHTSA) for the correct positioning of the head restraint (chi(2) (vertical) = 16.13, chi(2) (horizontal) = 10.80, p <.05). Only 6.7 percent of the subjects positioned their head restraint at the vertical distance of 6 cm or less (p <.05). However, 60 percent of the subjects positioned their head restraint at the recommended horizontal distance of 7 cm or less, but this was no different than could be expected by chance alone (p >.05). Interestingly, the 13.3 percent of the subjects who were aware of the vertical plane recommendations did not correctly position their own head restraint in the vertical plane. Similarly, only half of the subjects who were aware of the horizontal plane recommendations correctly positioned their head restraint in the horizontal plane. The data suggest that chance alone could account for the correct positioning of the head restraint in our subjects. The results of this cross-sectional study raise concerns about chiropractic intern knowledge and application of correct head restraint positioning. The importance of chiropractors informing patients of the correct head restraint position should be emphasized in chiropractic education to help minimize or prevent injury in patients involved in motor vehicle collisions.

Echolocation signals and transmission beam pattern of a false killer whale (Pseudorca crassidens).

PubMed

Au, W W; Pawloski, J L; Nachtigall, P E; Blonz, M; Gisner, R C

1995-07-01

The echolocation transmission beam pattern of a false killer whale (Pseudorca crassidens) was measured in the vertical and horizontal planes. A vertical array of seven broadband miniature hydrophones was used to measure the beam pattern in the vertical plane and a horizontal array of the same hydrophones was used in the horizontal plane. The measurements were performed in the open waters of Kaneohe Bay, Oahu, Hawaii, while the whale performed a target discrimination task. Four types of signals, characterized by their frequency spectra, were measured. Type-1 signals had a single low-frequency peak at 40 +/- 9 kHz and a low-amplitude shoulder at high frequencies. Type-2 signals had a bimodal frequency characteristic with a primary peak at 46 +/- 7 kHz and a secondary peak at 88 +/- 13 kHz. Type-3 signals were also bimodal but with a primary peak at 100 +/- 7 kHz and a secondary peak at 49 +/- 9 kHz. Type-4 signals had a single high-frequency peak at 104 +/- 7 kHz. The center frequency of the signals were found to be linearly correlated to the peak-to-peak source level, increasing with increasing source level. The major axis of the vertical beam was directed slightly downward between 0 and -5 degrees, in contrast to the +5 to 10 degrees for Tursiops and Delphinapterus. The beam in the horizontal plane was directed forward between 0 degrees and -5 degrees.(ABSTRACT TRUNCATED AT 250 WORDS)

Forced Vibrations of a Cantilever Beam

ERIC Educational Resources Information Center

Repetto, C. E.; Roatta, A.; Welti, R. J.

2012-01-01

The theoretical and experimental solutions for vibrations of a vertical-oriented, prismatic, thin cantilever beam are studied. The beam orientation is "downwards", i.e. the clamped end is above the free end, and it is subjected to a transverse movement at a selected frequency. Both the behaviour of the device driver and the beam's weak-damping…

Reassessment of the Necessity of the Proton Gantry: Analysis of Beam Orientations From 4332 Treatments at the Massachusetts General Hospital Proton Center Over the Past 10 Years

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Susu, E-mail: syan5@mgh.harvard.edu; Lu, Hsiao-Ming; Flanz, Jay

2016-05-01

Purpose: To retrospectively analyze the beam approaches used in gantry-based proton treatments, and to reassess the practical advantages of the gantry, compared with beam approaches that are achievable without a gantry, in the context of present-day technology. Methods and Materials: We reviewed the proton therapy plans of 4332 patients treated on gantries at our hospital, delivered by the double scattering technique (n=4228) and, more recently, pencil beam scanning (PBS) (n=104). Beam approaches, relative to the patient frame, were analyzed individually to identify cases that could be treated without a gantry. Three treatment configurations were considered, with the patient in lying position,more » sitting position, or both. The FIXED geometry includes a fixed horizontal portal. The BEND geometry enables a limited vertical inflection of the beam by up to 20°. The MOVE geometry allows for flexibility of the patient head and body setup. Results: The percentage of patients with head and neck tumors that could be treated without a gantry using double scattering was 44% in FIXED, 70% in 20° BEND, and 100% in 90° MOVE. For torso regions, 99% of patients could be treated in 20° BEND. Of 104 PBS treatments, all but 1 could be reproduced with FIXED geometry. The only exception would require a 10° BEND capability. Note here that the PBS treatments were applied to select anatomic sites, including only 2 patients with skull-base tumors. Conclusions: The majority of practical beam approaches can be realized with gantry-less delivery, aided by limited beam bending and patient movements. Practical limitations of the MOVE geometry, and treatments requiring a combination of lying and sitting positions, may lower the percentage of head and neck patients who could be treated without a gantry. Further investigation into planning, immobilization, and imaging is needed to remove the practical limitations and to facilitate proton treatment without a gantry.« less

Angular Alignment Testing of Laser Mirror Mounts Under Temperature Cycling

NASA Technical Reports Server (NTRS)

Bullock, K. T.; DeYoung, R. J.; Sandford, S. P.

1997-01-01

A number of commercial and custom-built laser mirror mounts were tested for angular alignment sensitivity during temperature cycling from room temperature (20 C) to 40 C. A Nd:YAG laser beam was reflected off a mirror that was held by the mount under test and was directed to a position-sensitive detector. Horizontal and vertical movement of the reflected beam was recorded, and the angular movement, as a function of temperature (coefficient of thermal tilt (CTT)) was calculated from these data. In addition, the amount of hysteresis in the movement after cycling from room temperature to 40 C and back was determined. All commercial mounts showed greater angular movement than the simpler National Aeronautics and Space Administration Lidar Atmospheric Sensing Experiment (NASA LASE) custom mirror mounts.

Reduction of Non-uniform Beam Filling Effects by Vertical Decorrelation: Theory and Simulations

NASA Technical Reports Server (NTRS)

Short, David; Nakagawa, Katsuhiro; Iguchi, Toshio

2013-01-01

Algorithms for estimating precipitation rates from spaceborne radar observations of apparent radar reflectivity depend on attenuation correction procedures. The algorithm suite for the Ku-band precipitation radar aboard the Tropical Rainfall Measuring Mission satellite is one such example. The well-known problem of nonuniform beam filling is a source of error in the estimates, especially in regions where intense deep convection occurs. The error is caused by unresolved horizontal variability in precipitation characteristics such as specific attenuation, rain rate, and effective reflectivity factor. This paper proposes the use of vertical decorrelation for correcting the nonuniform beam filling error developed under the assumption of a perfect vertical correlation. Empirical tests conducted using ground-based radar observations in the current simulation study show that decorrelation effects are evident in tilted convective cells. However, the problem of obtaining reasonable estimates of a governing parameter from the satellite data remains unresolved.

Grating angle magnification enhanced angular sensor and scanner

NASA Technical Reports Server (NTRS)

Sun, Ke-Xun (Inventor); Byer, Robert L. (Inventor)

2009-01-01

An angular magnification effect of diffraction is exploited to provide improved sensing and scanning. This effect is most pronounced for a normal or near-normal incidence angle in combination with a grazing diffraction angle, so such configurations are preferred. Angular sensitivity can be further enhanced because the width of the diffracted beam can be substantially less than the width of the incident beam. Normal incidence configurations with two symmetric diffracted beams are preferred, since rotation and vertical displacement can be readily distinguished. Increased sensitivity to vertical displacement can be provided by incorporating an interferometer into the measurement system. Quad cell detectors can be employed to provide sensitivity to rotation about the grating surface normal. A 2-D grating can be employed to provide sensitivity to angular displacements in two different planes (e.g., pitch and yaw). Combined systems can provide sensitivity to vertical displacement and to all three angular degrees of freedom.

Synchrotron oscillation effects on an rf-solenoid spin resonance

NASA Astrophysics Data System (ADS)

Benati, P.; Chiladze, D.; Dietrich, J.; Gaisser, M.; Gebel, R.; Guidoboni, G.; Hejny, V.; Kacharava, A.; Kamerdzhiev, V.; Kulessa, P.; Lehrach, A.; Lenisa, P.; Lorentz, B.; Maier, R.; Mchedlishvili, D.; Morse, W. M.; Öllers, D.; Pesce, A.; Polyanskiy, A.; Prasuhn, D.; Rathmann, F.; Semertzidis, Y. K.; Stephenson, E. J.; Stockhorst, H.; Ströher, H.; Talman, R.; Valdau, Yu.; Weidemann, Ch.; Wüstner, P.

2012-12-01

New measurements are reported for the time dependence of the vertical polarization of a 0.97GeV/c deuteron beam circulating in a storage ring and perturbed by an rf solenoid. The storage ring is the cooler synchrotron (COSY) located at the Forschungszentrum Jülich. The beam polarization was measured continuously using a 1.5 cm thick carbon target located at the edge of the circulating deuteron beam and the scintillators of the EDDA detector. An rf solenoid mounted on the ring was used to generate fields at and near the frequency of the 1-Gγ spin resonance. Measurements were made of the vertical beam polarization as a function of time with the operation of the rf solenoid in either fixed or continuously variable frequency mode. Using rf-solenoid strengths as large as 2.66×10-5revolutions/turn, slow oscillations (˜1Hz) were observed in the vertical beam polarization. When the circulating beam was continuously electron cooled, these oscillations completely reversed the polarization and showed no sign of diminishing in amplitude. But for the uncooled beam, the oscillation amplitude was damped to nearly zero within a few seconds. A simple spin-tracking model without the details of the COSY ring lattice was successful in reproducing these oscillations and demonstrating the sensitivity of the damping to the magnitude of the synchrotron motion of the beam particles. The model demonstrates that the characteristic features of measurements made in the presence of large synchrotron oscillations are distinct from the features of such measurements when made off resonance. These data were collected in preparation for a study of the spin coherence time, a beam property that needs to become long to enable a search for an electric dipole moment using a storage ring.

Ion related problems for the XLS ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bozoki, E.; Halama, H.

1989-07-11

The electron beam in the XLS will collide with the residual gas in the vacuum chamber. The positive ions will be trapped in the potential well of the electron beam. They will perform stable or unstable oscillations around the beam under the repetitive Coulomb force of the bunches. If not cleared, the captured ions will lead to partial or total neutralization of the beam, causing both, a decrease of life-time and a change in the vertical tunes as well as an increase in the tune-spread. They can also cause coherent transverse instabilities. The degree of neutralization {theta} that one canmore » tolerate, is primarily determined by the allowable tune shift, which of the XLS is between 1 and 5 10{sup {minus}3}. Electrostatic clearing electrodes will be used to keep the neutralization below the desired limit. In order to determine their location and the necessary clearing-rate and voltage, we examine the ion production rate, longitudinal velocity of ions in field-free regions and in the dipoles to see what distance the ions can travel without clearing before the neutralization of the beam reaches the prescribed limit, beam potential to see the locations of the potential wells, voltage requirements for ion clearing, critical mass for ion capture in the bunched beam, tune shift caused by neutralization of the beam, pressure rise due to the trapped ions and power dissipation due to beam image current. 13 refs., 3 figs., 4 tabs.« less

Non-mechanical optical path switching and its application to dual beam spectroscopy including gas filter correlation radiometry

NASA Technical Reports Server (NTRS)

Sachse, Glen W. (Inventor); Wang, Liang-Guo (Inventor)

1992-01-01

A non-mechanical optical switch is developed for alternately switching a monochromatic or quasi-monochromatic light beam along two optical paths. A polarizer polarizes light into a single, e.g., vertical component which is then rapidly modulated into vertical and horizontal components by a polarization modulator. A polarization beam splitter then reflects one of these components along one path and transmits the other along the second path. In the specific application of gas filter correlation radiometry, one path is directed through a vacuum cell and one path is directed through a gas correlation cell containing a desired gas. Reflecting mirrors cause these two paths to intersect at a second polarization beam splitter which reflects one component and transmits the other to recombine them into a polarization modulated beam which can be detected by an appropriate single sensor.

Investigations of Optical Properties of Active Regions in Vertical Cavity Surface Emitting Lasers Grown by MBE

DTIC Science & Technology

2002-06-03

Molecular beam epitaxy ; Planar microcavities; Vertical cavity surface emitting lasers 1... Vertical Cavity Surface Emitting Lasers Grown by MBE DISTRIBUTION: Approved for public release, distribution unlimited This paper is part of the...S-581 83 Linkiping, Sweden Abstract The design of the vertical cavity surface emitting lasers ( VCSELs ) needs proper tuning of many

Highly Directional Sonar Beam of Narwhals (Monodon monoceros) Measured with a Vertical 16 Hydrophone Array.

PubMed

Koblitz, Jens C; Stilz, Peter; Rasmussen, Marianne H; Laidre, Kristin L

2016-01-01

Recordings of narwhal (Monodon monoceros) echolocation signals were made using a linear 16 hydrophone array in the pack ice of Baffin Bay, West Greenland in 2013 at eleven sites. An average -3 dB beam width of 5.0° makes the narwhal click the most directional biosonar signal reported for any species to date. The beam shows a dorsal-ventral asymmetry with a narrower beam above the beam axis. This may be an evolutionary advantage for toothed whales to reduce echoes from the water surface or sea ice surface. Source level measurements show narwhal click intensities of up to 222 dB pp re 1 μPa, with a mean apparent source level of 215 dB pp re 1 μPa. During ascents and descents the narwhals perform scanning in the vertical plane with their sonar beam. This study provides valuable information for reference sonar parameters of narwhals and for the use of acoustic monitoring in the Arctic.

Highly Directional Sonar Beam of Narwhals (Monodon monoceros) Measured with a Vertical 16 Hydrophone Array

PubMed Central

Koblitz, Jens C.; Stilz, Peter; Rasmussen, Marianne H.; Laidre, Kristin L.

2016-01-01

Recordings of narwhal (Monodon monoceros) echolocation signals were made using a linear 16 hydrophone array in the pack ice of Baffin Bay, West Greenland in 2013 at eleven sites. An average -3 dB beam width of 5.0° makes the narwhal click the most directional biosonar signal reported for any species to date. The beam shows a dorsal-ventral asymmetry with a narrower beam above the beam axis. This may be an evolutionary advantage for toothed whales to reduce echoes from the water surface or sea ice surface. Source level measurements show narwhal click intensities of up to 222 dB pp re 1 μPa, with a mean apparent source level of 215 dB pp re 1 μPa. During ascents and descents the narwhals perform scanning in the vertical plane with their sonar beam. This study provides valuable information for reference sonar parameters of narwhals and for the use of acoustic monitoring in the Arctic. PMID:27828956

SEQUOIA: A Newly Operating Chopper Spectrometer at the SNS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kolesnikov, Alexander I; Sherline, Todd E; Clancy, James P

2010-01-01

A fine resolution chopper spectrometer (SEQUOIA) recently received first neutrons at the SNS. The commissioning phase of the instrument is underway. SEQUOIA is designed to utilize neutrons of an incident energy (Ei) between 10-2000 meV. A monochromatic beam is provided on a sample, 20 m from the decoupled ambient temperature H2O moderator, by filtering the white beam with a Fermi chopper located 18 m from the source. After interacting with the sample, neutrons are detected by an array of 3He linear position sensitive tubes located on a vertical cylinder with a radius of 5.5 m. This contribution presents current resultsmore » from the commissioning experiments and compares SEQUOIA s actual and predicted performance. These commissioning experiments include characterization of the beam by monitors, determination of the chopper phase offsets, and runs with V and C4H2I2S. The predicted performance is provided by analytical calculations and Monte Carlo simulations.« less

Combined VIS-IR spectrometer with vertical probe beam

NASA Astrophysics Data System (ADS)

Protopopov, V.

2017-12-01

A prototype of a combined visible-infrared spectrometer with a vertical probe beam is designed and tested. The combined spectral range is 0.4-20 μ with spatial resolution 1 mm. Basic features include the ability to measure both visibly transparent and opaque substances, as well as buried structures, such as in semiconductor industry; horizontal orientation of a sample, including semiconductor wafers; and reflection mode of operation, delivering twice the sensitivity compared to the transmission mode.

Recent Vertical External Cavity Surface Emitting Lasers (VECSELs) Developments for Sensor Applications (POSTPRINT)

DTIC Science & Technology

2013-02-01

edge-emitting strained InxGa1−xSb/AlyGa1−ySb quantum well struc- tures using solid-source molecular beam epitaxy (MBE) with varying barrier heights...intersubband quantum wells. The most common high-power edge-emitting semiconductor lasers suffter from poor beam quality, due primarily to the linewidth...reduces the power scalability of semiconductor lasers. In vertical cavity surface emitting lasers ( VCSELs ), light propagates parallel to the growth

Effects of correlations between particle longitudinal positions and transverse plane on bunch length measurement: a case study on GBS electron LINAC at ELI-NP

NASA Astrophysics Data System (ADS)

Sabato, L.; Arpaia, P.; Cianchi, A.; Liccardo, A.; Mostacci, A.; Palumbo, L.; Variola, A.

2018-02-01

In high-brightness LINear ACcelerators (LINACs), electron bunch length can be measured indirectly by a radio frequency deflector (RFD). In this paper, the accuracy loss arising from non-negligible correlations between particle longitudinal positions and the transverse plane (in particular the vertical one) at RFD entrance is analytically assessed. Theoretical predictions are compared with simulation results, obtained by means of ELEctron Generation ANd Tracking (ELEGANT) code, in the case study of the gamma beam system (GBS) at the extreme light infrastructure—nuclear physics (ELI-NP). In particular, the relative error affecting the bunch length measurement, for bunches characterized by both energy chirp and fixed correlation coefficients between longitudinal particle positions and the vertical plane, is reported. Moreover, the relative error versus the correlation coefficients is shown for fixed RFD phase 0 rad and π rad. The relationship between relative error and correlations factors can help the decision of using the bunch length measurement technique with one or two vertical spot size measurements in order to cancel the correlations contribution. In the case of the GBS electron LINAC, the misalignment of one of the quadrupoles before the RFD between  -2 mm and 2 mm leads to a relative error less than 5%. The misalignment of the first C-band accelerating section between  -2 mm and 2 mm could lead to a relative error up to 10%.

Coupling Correction and Beam Dynamics at Ultralow Vertical Emittance in the ALS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steier, Christoph; Robin, D.; Wolski, A.

2008-03-17

For synchrotron light sources and for damping rings of linear colliders it is important to be able to minimize the vertical emittance and to correct the spurious vertical dispersion. This allows one to maximize the brightness and/or the luminosity. A commonly used tool to measure the skew error distribution is the analysis of orbit response matrices using codes like LOCO. Using the new Matlab version of LOCO and 18 newly installed power supplies for individual skew quadrupoles at the ALS the emittance ratio could be reduced below 0.1% at 1.9 GeV yielding a vertical emittance of about 5 pm. Atmore » those very low emittances, additional effects like intra beam scattering become more important, potentially limiting the minimum emittance for machine like the damping rings of linear colliders.« less

Ion shaking in the 200 MeV XLS-ring

NASA Astrophysics Data System (ADS)

Bozoki, E.; Kramer, S. L.

1992-03-01

It has been shown that ions, trapped inside the beam's potential, can be removed by the clearing electrodes when the amplitude of the ion oscillation is increased by vertically shaking the ions. We will report on a similar experiment in the 200 MeV XLS ring. The design of the ion clearing system for the ring and the first results obtained were already reported. In the present series of experiments, RF voltage was applied on a pair of vertical strip-lines. The frequency was scanned in the range of the ion (from H2 to CO2) bounce frequencies in the ring (1-10 MHz). The response of the beam size, vertical betatron tune, and lifetime was studied.

Effect of forming stresses on the strength of curved laminated beams of loblolly pine

Treesearch

George E. Woodson; Frederick F. Wangaard

1969-01-01

Curvature-stress factors reflecting the effect of forming stresses in producing curved beams of thin vertical-grain laminations of clear wood have been determined for loblolly pine. Strength retention of curved beams decreases with increasing severity of curvature but not to the degree suggested by the Wilson equation commonly used in design. Curved beams loaded on the...

Bipolar Cascade Vertical-Cavity Surface-Emitting Lasers for RF Photonic Link Applications

DTIC Science & Technology

2007-09-01

6 IV Current versus Voltage . . . . . . . . . . . . . . . . . . . . . 7 MBE Molecular Beam Epitaxy ...of carrying maximum photocur- rent. Numerous material parameters have been studied. Growth parameters for molecular beam epitaxy (MBE), metal-organic...12 MOCVD Metal-Organic Chemical Vapor Deposition . . . . . . . . . . 12 CBE Chemical Beam Epitaxy . . . . . . . . . . . . . . . . . . . . 12 LPE

Improved double-pass michelson interferometer

NASA Technical Reports Server (NTRS)

Schindler, R. A.

1978-01-01

Interferometer design separates beams by offsetting centerlines of cat's-eye retroreflectors vertically rather than horizontally. Since beam splitter is insensitive to minimum-thickness condition in this geometry, relatively-low-cost, optically flat plate can be used.

12. VIEW OF FLOOR BEAMS, GUSSET PLATES, RIVET CONNECTIONS, LACED ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. VIEW OF FLOOR BEAMS, GUSSET PLATES, RIVET CONNECTIONS, LACED VERTICALS AND LATTICE RAILING, LOOKING NORTHWEST - Attica Bridge, Spanning Deer Creek on County Road 500 East, Young America, Cass County, IN

Beam pointing direction changes in a misaligned Porro prism resonator

NASA Astrophysics Data System (ADS)

Lee, Jyh-Fa; Leung, Chung-Yee

1988-07-01

The relative change of the beam pointing direction for a misaligned Porro prism resonator has been analyzed, using an oscillation axis concept for the Porro prism resonator to find the beam direction. Expressions for the beam tilting angles are presented which show that the angular misalignment in the horizontal direction will result in beam tilting in both the horizontal and vertical directions. Good agreement between experimental and theoretical results is found.

A Tactile Sensor Using Piezoresistive Beams for Detection of the Coefficient of Static Friction

PubMed Central

Okatani, Taiyu; Takahashi, Hidetoshi; Noda, Kentaro; Takahata, Tomoyuki; Matsumoto, Kiyoshi; Shimoyama, Isao

2016-01-01

This paper reports on a tactile sensor using piezoresistive beams for detection of the coefficient of static friction merely by pressing the sensor against an object. The sensor chip is composed of three pairs of piezoresistive beams arranged in parallel and embedded in an elastomer; this sensor is able to measure the vertical and lateral strains of the elastomer. The coefficient of static friction is estimated from the ratio of the fractional resistance changes corresponding to the sensing elements of vertical and lateral strains when the sensor is in contact with an object surface. We applied a normal force on the sensor surface through objects with coefficients of static friction ranging from 0.2 to 1.1. The fractional resistance changes corresponding to vertical and lateral strains were proportional to the applied force. Furthermore, the relationship between these responses changed according to the coefficients of static friction. The experimental result indicated the proposed sensor could determine the coefficient of static friction before a global slip occurs. PMID:27213374

A specialized bioengineering ion beam line

NASA Astrophysics Data System (ADS)

Yu, L. D.; Sangyuenyongpipat, S.; Sriprom, C.; Thongleurm, C.; Suwanksum, R.; Tondee, N.; Prakrajang, K.; Vilaithong, T.; Brown, I. G.; Wiedemann, H.

2007-04-01

A specialized bioengineering ion beam line has recently been completed at Chiang Mai University to meet rapidly growing needs of research and application development in low-energy ion beam biotechnology. This beam line possesses special features: vertical main beam line, low-energy (30 keV) ion beams, double swerve of the beam, a fast pumped target chamber, and an in-situ atomic force microscope (AFM) system chamber. The whole beam line is situated in a bioclean environment, occupying two stories. The quality of the ion beam has been studied. It has proved that this beam line has significantly contributed to our research work on low-energy ion beam biotechnology.

15. Detail view of connection between vertical posts and deck ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

15. Detail view of connection between vertical posts and deck beam. Jack Boucher, photographer, 1983 - Neshanic Station Lenticular Truss Bridge, State Route 567, spanning South Branch of Raritan River, Neshanic Station, Somerset County, NJ

High power tapered lasers with optimized photonic crystal structure for low divergence and high efficiency

NASA Astrophysics Data System (ADS)

Ma, Xiaolong; Qu, Hongwei; Qi, Aiyi; Zhou, Xuyan; Ma, Pijie; Liu, Anjin; Zheng, Wanhua

2018-04-01

High power tapered lasers are designed and fabricated. A one-dimensional photonic crystal structure in the vertical direction is adopted to narrow the far field divergence. The thickness of the defect layer and the photonic crystal layers are optimized by analyzing the optical field theoretically. For tapered lasers, the continuous-wave power is 7.3 W and the pulsed power is 17 W. A maximum wall-plug efficiency of 46% under continuous-wave operation and 49.3% in pulsed mode are obtained. The beam divergences are around 11° and 6° for the vertical and lateral directions, respectively. High beam qualities are also obtained with a vertical M2 value of 1.78 and a lateral M2 value of 1.62. As the current increases, the lateral M2 value increases gradually while the vertical M2 value remains around 2.

Radar - ARL Wind Profilerwith RASS, Boardman - Raw Data

DOE Data Explorer

Gottas, Daniel

2017-10-23

**Winds** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

Radar - ANL Wind Profiler with RASS, Yakima - Raw Data

DOE Data Explorer

Gottas, Daniel

2017-10-23

**Winds** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

Radar - ESRL Wind Profiler with RASS, Condon - Raw Data

DOE Data Explorer

Gottas, Daniel

2017-10-23

**Winds** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

Radar - ANL Wind Profiler with RASS, Walla Walla - Raw Data

DOE Data Explorer

Gottas, Daniel

2017-10-23

**Winds** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

Radar - ESRL Wind Profiler with RASS, Prineville - Raw Data

DOE Data Explorer

Gottas, Daniel

2017-10-23

**Winds** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

Radar - ESRL Wind Profiler with RASS, Troutdale - Raw Data

DOE Data Explorer

Gottas, Daniel

2017-10-23

**Winds** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

Radar - ANL Wind Profiler with RASS, Goldendale - Raw Data

DOE Data Explorer

Gottas, Daniel

2017-10-23

**Winds** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

Radar - ESRL Wind Profiler with RASS, Wasco Airport - Raw Data

DOE Data Explorer

Gottas, Daniel

2017-10-23

**Winds** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

Thermal deformation of cryogenically cooled silicon crystals under intense X-ray beams: measurement and finite-element predictions of the surface shape

PubMed Central

Zhang, Lin; Sánchez del Río, Manuel; Monaco, Giulio; Detlefs, Carsten; Roth, Thomas; Chumakov, Aleksandr I.; Glatzel, Pieter

2013-01-01

X-ray crystal monochromators exposed to white-beam X-rays in third-generation synchrotron light sources are subject to thermal deformations that must be minimized using an adequate cooling system. A new approach was used to measure the crystal shape profile and slope of several cryogenically cooled (liquid nitrogen) silicon monochromators as a function of beam power in situ and under heat load. The method utilizes multiple angular scans across the Bragg peak (rocking curve) at various vertical positions of a narrow-gap slit downstream from the monochromator. When increasing the beam power, the surface of the liquid-nitrogen-cooled silicon crystal deforms from a concave shape at low heat load to a convex shape at high heat load, passing through an approximately flat shape at intermediate heat load. Finite-element analysis is used to calculate the crystal thermal deformations. The simulated crystal profiles and slopes are in excellent agreement with experiments. The parameters used in simulations, such as material properties, absorbed power distribution on the crystal and cooling boundary conditions, are described in detail as they are fundamental for obtaining accurate results. PMID:23765298

The solar ultraviolet B radiation protection provided by shading devices with regard to its diffuse component.

PubMed

Kudish, Avraham I; Harari, Marco; Evseev, Efim G

2011-10-01

The composition of the incident solar global ultraviolet B (UVB) radiation with regard to its beam and diffuse radiation fractions is highly relevant with regard to outdoor sun protection. This is especially true with respect to sun protection during leisure-time outdoor sun exposure at the shore and pools, where people tend to escape the sun under shade trees or different types of shading devices, e.g., umbrellas, overhangs, etc., believing they offer protection from the erythemal solar radiation. The degree of sun protection offered by such devices is directly related to the composition of the solar global UVB radiation, i.e., its beam and diffuse fractions. The composition of the incident solar global UVB radiation can be determined by measuring the global UVB (using Solar Light Co. Inc., Model 501A UV-Biometer) and either of its components. The beam component of the UVB radiation was determined by measuring the normal incidence beam radiation using a prototype, tracking instrument consisting of a Solar Light Co. Inc. Model 501A UV-Biometer mounted on an Eppley Solar Tracker Model St-1. The horizontal beam component of the global UVB radiation was calculated from the measured normal incidence using a simple geometric correlation and the diffuse component is determined as the difference between global and horizontal beam radiations. Horizontal and vertical surfaces positioned under a horizontal overhang/sunshade or an umbrella are not fully protected from exposure to solar global UVB radiation. They can receive a significant fraction of the UVB radiation, depending on their location beneath the shading device, the umbrella radius and the albedo (reflectance) of the surrounding ground surface in the case of a vertical surface. Shading devices such as an umbrella or horizontal overhang/shade provide relief from the solar global radiation and do block the solar global UVB radiation to some extent; nevertheless, a significant fraction of the solar global UVB radiation does penetrate this supposedly 'protective or comfort zone'. As a result, it is imperative to either apply sunscreen or cover up the exposed body surfaces even when under such shading devices. © 2011 John Wiley & Sons A/S.

Momentum Flux Determination Using the Multi-beam Poker Flat Incoherent Scatter Radar

NASA Technical Reports Server (NTRS)

Nicolls, M. J.; Fritts, D. C.; Janches, Diego; Heinselman, C. J.

2012-01-01

In this paper, we develop an estimator for the vertical flux of horizontal momentum with arbitrary beam pointing, applicable to the case of arbitrary but fixed beam pointing with systems such as the Poker Flat Incoherent Scatter Radar (PFISR). This method uses information from all available beams to resolve the variances of the wind field in addition to the vertical flux of both meridional and zonal momentum, targeted for high-frequency wave motions. The estimator utilises the full covariance of the distributed measurements, which provides a significant reduction in errors over the direct extension of previously developed techniques and allows for the calculation of an error covariance matrix of the estimated quantities. We find that for the PFISR experiment, we can construct an unbiased and robust estimator of the momentum flux if sufficient and proper beam orientations are chosen, which can in the future be optimized for the expected frequency distribution of momentum-containing scales. However, there is a potential trade-off between biases and standard errors introduced with the new approach, which must be taken into account when assessing the momentum fluxes. We apply the estimator to PFISR measurements on 23 April 2008 and 21 December 2007, from 60-85 km altitude, and show expected results as compared to mean winds and in relation to the measured vertical velocity variances.

Optical Phased Array Antennas using Coupled Vertical Cavity Surface Emitting Lasers

NASA Technical Reports Server (NTRS)

Mueller, Carl H.; Rojas, Roberto A.; Nessel, James A.; Miranda, Felix A.

2007-01-01

High data rate communication links are needed to meet the needs of NASA as well as other organizations to develop space-based optical communication systems. These systems must be robust to high radiation environments, reliable, and operate over a wide temperature range. Highly desirable features include beam steering capability, reconfigurability, low power consumption, and small aperture size. Optical communication links, using coupled vertical cavity surface emitting laser radiating elements are promising candidates for the transmit portion of these communication links. In this talk we describe a mission scenario, and how the antenna requirements are derived from the mission needs. We describe a potential architecture for this type of antenna, and outline the advantages and drawbacks of this approach relative to competing technologies. The technology we are proposing used coupled arrays of 1550 nm vertical cavity surface emitting lasers for transmission. The feasibility of coupling these arrays together, to form coherent high-power beams that can be modulated at data rates exceeding 1 Gbps, will be explored. We will propose an architecture that enables electronic beam steering, thus mitigating the need for ancillary acquisition, tracking and beam pointing equipment such as needed for current optical communicatin systems. The beam-steering capability we are proposing also opens the possibility of using this technology for inter-satellite communicatin links, and satellite-to-surface links.

Vacuum compatible sample positioning device for matrix assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aizikov, Konstantin; Lin, Tzu-Yung; Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts 02215

The high mass accuracy and resolving power of Fourier transform ion cyclotron resonance mass spectrometers (FT-ICR MS) make them ideal mass detectors for mass spectrometry imaging (MSI), promising to provide unmatched molecular resolution capabilities. The intrinsic low tolerance of FT-ICR MS to RF interference, however, along with typically vertical positioning of the sample, and MSI acquisition speed requirements present numerous engineering challenges in creating robotics capable of achieving the spatial resolution to match. This work discusses a two-dimensional positioning stage designed to address these issues. The stage is capable of operating in {approx}1 x 10{sup -8} mbar vacuum. The rangemore » of motion is set to 100 mm x 100 mm to accommodate large samples, while the positioning accuracy is demonstrated to be less than 0.4 micron in both directions under vertical load over the entire range. This device was integrated into three different matrix assisted laser desorption/ionization (MALDI) FT-ICR instruments and showed no detectable RF noise. The ''oversampling'' MALDI-MSI experiments, under which the sample is completely ablated at each position, followed by the target movement of the distance smaller than the laser beam, conducted on the custom-built 7T FT-ICR MS demonstrate the stability and positional accuracy of the stage robotics which delivers high spatial resolution mass spectral images at a fraction of the laser spot diameter.« less

Ion shaking in the 200 MeV XLS-ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bozoki, E.; Kramer, S.L.

1992-01-01

It has been shown that ions, trapped inside the beam's potential, can be removed by the clearing electrodes when the amplitude of the ion oscillation is increased by vertically shaking the ions. We will report on a similar experiment in the 200 Mev XLS ring. The design of the ion clearing system for the ring and the first results obtained, were already reported. In the present series of experiments, RF voltage was applied on a pair of vertical strip-lines. The frequency was scanned in the range of the ion (from H[sub 2] to CO[sub 2]) bounce frequencies in the ringmore » (1--10 MHz). The response of the beam size, vertical betatron tune and lifetime was studied.« less

First neutron spectroscopy measurements with a pixelated diamond detector at JET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muraro, A., E-mail: muraro@ifp.cnr.it; Giacomelli, L.; Grosso, G.

2016-11-15

A prototype Single crystal Diamond Detector (SDD) was installed at the Joint European Torus (JET) in 2013 along an oblique line of sight and demonstrated the possibility to carry out neutron spectroscopy measurements with good energy resolution and detector stability in discharges heated by neutral beam injection and radio-frequency waves. Starting from these positive results, within the Vertical Neutron Spectrometer project of the Joint European Torus, we have developed a pixelated instrument consisting of a matrix of 12 independent SDDs, called the Diamond Vertical Neutron Spectrometer (DVNS), which boosts the detection efficiency of a single SDD by an order ofmore » magnitude. In this paper we describe the main features of the DVNS, including the detector design, energy resolution, and data acquisition system for on-line processing. Preliminary spectroscopy measurements of 2.5 MeV neutrons from the present deuterium plasma at JET are finally presented.« less

First neutron spectroscopy measurements with a pixelated diamond detector at JET.

PubMed

Muraro, A; Giacomelli, L; Nocente, M; Rebai, M; Rigamonti, D; Belli, F; Calvani, P; Figueiredo, J; Girolami, M; Gorini, G; Grosso, G; Murari, A; Popovichev, S; Trucchi, D M; Tardocchi, M

2016-11-01

A prototype Single crystal Diamond Detector (SDD) was installed at the Joint European Torus (JET) in 2013 along an oblique line of sight and demonstrated the possibility to carry out neutron spectroscopy measurements with good energy resolution and detector stability in discharges heated by neutral beam injection and radio-frequency waves. Starting from these positive results, within the Vertical Neutron Spectrometer project of the Joint European Torus, we have developed a pixelated instrument consisting of a matrix of 12 independent SDDs, called the Diamond Vertical Neutron Spectrometer (DVNS), which boosts the detection efficiency of a single SDD by an order of magnitude. In this paper we describe the main features of the DVNS, including the detector design, energy resolution, and data acquisition system for on-line processing. Preliminary spectroscopy measurements of 2.5 MeV neutrons from the present deuterium plasma at JET are finally presented.

Geometric phase due to orbit-orbit interaction: rotating LP11 modes in a two-mode fiber

NASA Astrophysics Data System (ADS)

Pradeep Chakravarthy, T.; Naik, Dinesh N.; Viswanathan, Nirmal K.

2017-10-01

Accumulation of geometric phase due to non-coplanar propagation of higher-order modes in an optical fiber is experimentally demonstrated. Vertically-polarized LP11 fiber mode, excited in a horizontally-held, torsion-free, step-index, two-mode optical fiber, rotates due to asymmetry in the propagating k-vectors, arising due to off-centered beam location at the fiber input. Perceiving the process as due to rotation of the fiber about the off-axis launch position, the orbital Berry phase accumulation upon scanning the launch position in a closed-loop around the fiber axis manifests as rotational Doppler effect, a consequence of orbit-orbit interaction. The anticipated phase accumulation as a function of the input launch position, observed through interferometry is connected to the mode rotation angle, quantified using the autocorrelation method.

Flow tilt angle measurements using lidar anemometry

NASA Astrophysics Data System (ADS)

Dellwik, Ebba; Mann, Jakob

2010-05-01

A new way of estimating near-surface mean flow tilt angles from ground based Doppler lidar measurements is presented. The results are compared with traditional mast based in-situ sonic anemometry. The tilt angle assessed with the lidar is based on 10 or 30 minute mean values of the velocity field from a conically scanning lidar. In this mode of measurement, the lidar beam is rotated in a circle by a prism with a fixed angle to the vertical at varying focus distances. By fitting a trigonometric function to the scans, the mean vertical velocity can be estimated. Lidar measurements from (1) a fetch-limited beech forest site taken at 48-175m above ground level, (2) a reference site in flat agricultural terrain and (3) a second reference site in very complex terrain are presented. The method to derive flow tilt angles and mean vertical velocities from lidar has several advantages compared to sonic anemometry; there is no flow distortion caused by the instrument itself, there are no temperature effects and the instrument misalignment can be corrected for by comparing tilt estimates at various heights. Contrary to mast-based instruments, the lidar measures the wind field with the exact same alignment error at a multitude of heights. Disadvantages with estimating vertical velocities from a lidar compared to mast-based measurements are slightly increased levels of statistical errors due to limited sampling time, because the sampling is disjunct and a requirement for homogeneous flow. The estimated mean vertical velocity is biased if the flow over the scanned circle is not homogeneous. However, the error on the mean vertical velocity due to flow inhomogeneity can be approximated by a function of the angle of the lidar beam to the vertical, the measurement height and the vertical gradient of the mean vertical velocity, whereas the error due to flow inhomogeneity on the horizontal mean wind speed is independent of the lidar beam angle. For the presented measurements over forest, it is evaluated that the systematic error due to the inhomogeneity of the flow is less than 0.2 degrees. Other possibilities for utilizing lidars for flow tilt angle and mean vertical velocities are discussed.

Effect of electron beam cooling on transversal and longitudinal emittance of an external proton beam

NASA Astrophysics Data System (ADS)

Kilian, K.; Machner, H.; Magiera, A.; Prasuhn, D.; von Rossen, P.; Siudak, R.; Stein, H. J.; Stockhorst, H.

2018-02-01

Benefits of electron cooling to the quality of extracted ion beams from storage rings are discussed. The transversal emittances of an external proton beam with and without electron cooling at injection energy are measured with the GEM detector assembly. While the horizontal emittance remains the vertical emittance shrinks by the cooling process. The longitudinal momentum variance is also reduced by cooling.

Current status of the IOTA interferometer

NASA Astrophysics Data System (ADS)

Carleton, Nathaniel P.; Traub, Wesley A.; Lacasse, Marc G.; Nisenson, Peter; Pearlman, Michael R.; Reasenberg, Robert D.; Xu, Xinqi; Coldwell, Charles M.; Panasyuk, Alexander; Benson, James A.; Papaliolios, Costas; Predmore, Read; Schloerb, F. P.; Dyck, H. M.; Gibson, David M.

1994-06-01

The first two telescopes of the Infrared-Optical Telescope Array (IOTA) project are now in place and yielding data at the Smithsonian Institution's F. L. Whipple Observatory on Mt. Hopkins, near Tucson, Arizona. The IOTA collectors are 45 cm in diameter, and may be moved to various stations in an L-shaped configuration with a maximum baseline of 38 m. A third collector will be added as soon as funding permits. Each light-collector assembly consists of a siderostat feeding a stationary afocal Cassegrain telescope that produces a 10-X reduced parallel beam, which is in turn directed vertically downward by a piezo-driven active mirror that stabilizes the ultimate image position. The reduced beams enter an evacuated envelope and proceed to the corner of the array, where they are turned back along one arm for path compensation. The delay line, in one beam, consists of two parts: one dihedral reflector positioned in a slew-and-clamp mode to give the major part of the desired delay; and a second dihedral mounted on an air-bearing carriage to provide the variable delay that is needed. After delay, the beams exit from the vacuum and are directed by dichroic mirrors into the infrared beam-combination and detection system. The visible light passes on to another area, to the image-tracker detectors and the visible-light combination and detection system. The beams are combined in pupil-plane mode on beam splitters. The combined IR beams are conveyed to two cooled single-element InSb detectors. The combined visible-light beams are focussed by lenslet arrays onto multimode optical fibers that lead to the slit of a specially-designed prism spectrometer. For the visible mode, the delay line is run at several wavelengths on one side of the zero- path point, so that several cycles of interference occur across the spectrum. First results were obtained with the IR system, giving visibilities for several K and M stars, using 2.2 micrometers radiation on a N-S baseline of 21.2 m. From these measurements we obtained preliminary estimates of effective stellar diameters in the K band.

SU-F-J-125: Effects of Couch Position Variability On Dosimetric Accuracy with An MRI-Guided Co-60 Radiation Therapy Machine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chow, P; Thomas, D; Agazaryan, N

2016-06-15

Purpose: Magnetic resonance imaging (MRI) guidance in radiation therapy brings real-time imaging and adaptive planning into the treatment vault where it can account for interfraction and intrafraction movement of soft tissue. The only commercially-available MRI-guided radiation therapy device is a three-head 60Co and MRI system with an integrated treatment planning system (TPS). An up to 20% attenuation of the beam by the couch is well modeled in the TPS. However, variations in the patient’s day-to-day position introduce discrepancies in the actual couch position relative its location as modeled in the treatment plan. For this reason, our institution avoids plans withmore » beams that pass through or near the couch edges. This study looks at plans without restriction on beam angles and investigates the effects of couch shift by simulating shifts of the couch relative to the patient, in order to determine whether couch edge avoidance restrictions can be lifted. Methods: A total of 27 plans from 23 patients were investigated. Couch shifts of 1 and 2 cm were introduced in combinations of lateral and vertical direction to simulate variations in patient positioning on the couch giving 16 shifted plans per reference plan. The shift values of 1 and 2 cm were based on shifts recorded in 320 treatment fractions. Results: Measured couch attenuation versus TPS modeled agreed within 2.1%. Planning Target Volume (PTV) D95 changed less than 1% for 1 and 2 cm couch shifts in only the x-direction and less than 3% for all directions. Conclusion: The dosimetry of all plans with shifts up to ±2 cm was within reasonable clinical tolerances. Robustness of a plan to couch shifts can be tested in the TPS. Inclusion of beams traversing the couch edges should be considered if an improvement in plan quality or delivery time can be achieved.« less

SU-G-TeP1-13: Reclined Total Skin Electron Treatment Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathew, D; Gerbi, B

Purpose: The purpose is to describe a new reclined technique for treatment of weakened patients that require total skin electron irradiation. Methods: This technique is a modification of a previously published reclined technique differing in that all six patient positions are treated with the gantry angled 60° from vertically down. The patient is located at a treatment distance of 330 cm SSD along the CA of the beam. The 3/8′ thick Lexan beam spoiler is placed 25 cm from the most proximal surface of the patient for all patient treatment positions. To produce a flat, uniform field of ∼190 cmmore » length, the patient was moved longitudinally by an experimentally determined distance. Kodak EDR2 and EBT3 Radiochromic film were placed around the periphery of the phantom, and OSLs were placed every 30° around the phantom periphery to determine output and surface dose uniformity. A piece of Kodak EDR2 was sandwiched between the two slabs of the 30 cm diameter phantom to determine beam penetration. Results: Field uniformity shifting the patient ±75 cm was ±5% over a treatment span of 190 cm. The dose variation around the periphery of the 30 cm diameter phantom varied by <±5% with the maximum values observed at the 0°-300°, 60° locations with the minimum values at the 30°-330°, 60° locations. Results obtained using Kodak EDR2, EBT3 Radiochromic film, and OSLs agreed to within ±5%. Conclusion: This technique provides a very efficient and convenient means by which to treat the entire skin surface of patients incapable of standing for treatment. It provides a treatment field that is both large and uniform enough for adults along with a convenient way to treat four of the six patient treatment positions. The beam spoiler lies to the side of the patient allowing easy access for patient positioning.« less

IV-VI compound midinfrared high-reflectivity mirrors and vertical-cavity surface-emitting lasers grown by molecular-beam epitaxy

NASA Astrophysics Data System (ADS)

Shi, Z.; Xu, G.; McCann, P. J.; Fang, X. M.; Dai, N.; Felix, C. L.; Bewley, W. W.; Vurgaftman, I.; Meyer, J. R.

2000-06-01

Midinfrared broadband high-reflectivity Pb1-xSrxSe/BaF2 distributed Bragg reflectors and vertical-cavity surface-emitting lasers (VCSELs) with PbSe as the active material were grown by molecular-beam epitaxy. Because of an extremely high index contrast, mirrors with only three quarter-wave layer pairs had reflectivities exceeding 99%. For pulsed optical pumping, a lead salt VCSEL emitting at the cavity wavelength of 4.5-4.6 μm operated nearly to room temperature (289 K).

High Resolution BPM Upgrade for the ATF Damping Ring at KEK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eddy, N.; Briegel, C.; Fellenz, B.

2011-08-17

A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and digital down-conversion techniques, digital signal processing, and also implements a new automatic gain error correction schema. The technical concept and realization as well as results of beam studies are presented. The next generation of linear colliders require ultra-low vertical emittance of <2 pm-rad. The damping ring at the KEK Accelerator Test Facilitymore » (ATF) is designed to demonstrate this mission critical goal. A high resolution beam position monitor (BPM) system for the damping ring is one of the key tools for realizing this goal. The BPM system needs to provide two distnict measurements. First, a very high resolution ({approx}100-200nm) closed-orbit measurement which is averaged over many turns and realized with narrowband filter techniques - 'narrowband mode'. This is needed to monitor and steer the beam along an optimum orbit and to facilitate beam-based alignment to minimize non-linear field effects. Second, is the ability to make turn by turn (TBT) measurements to support optics studies and corrections necessary to achieve the design performance. As the TBT measurement necessitates a wider bandwidth, it is often referred to as 'wideband mode'. The BPM upgrade was initiated as a KEK/SLAC/FNAL collaboration in the frame of the Global Design Initiative of the International Linear Collider. The project was realized and completed using Japan-US funds with Fermilab as the core partner.« less

Vertical beam size measurement in the CESR-TA e+e- storage ring using x-rays from synchrotron radiation

NASA Astrophysics Data System (ADS)

Alexander, J. P.; Chatterjee, A.; Conolly, C.; Edwards, E.; Ehrlichman, M. P.; Fontes, E.; Heltsley, B. K.; Hopkins, W.; Lyndaker, A.; Peterson, D. P.; Rider, N. T.; Rubin, D. L.; Savino, J.; Seeley, R.; Shanks, J.; Flanagan, J. W.

2014-06-01

We describe the construction and operation of an X-ray beam size monitor (xBSM), a device measuring e+ and e- beam sizes in the CESR-TA storage ring using synchrotron radiation. The device can measure vertical beam sizes of 10-100μm on a turn-by-turn, bunch-by-bunch basis at e± beam energies of ~2GeV. At such beam energies the xBSM images X-rays of ɛ≈1-10keV (λ≈0.1-1nm) that emerge from a hard-bend magnet through a single- or multiple-slit (coded aperture) optical element onto an array of 32 InGaAs photodiodes with 50μm pitch. Beamlines and detectors are entirely in-vacuum, enabling single-shot beam size measurement down to below 0.1 mA (2.5×109 particles) per bunch and inter-bunch spacing of as little as 4 ns. At Eb=2.1GeV, systematic precision of ~1μm is achieved for a beam size of ~12μm; this is expected to scale as ∝1/σb and ∝1/Eb. Achieving this precision requires comprehensive alignment and calibration of the detector, optical elements, and X-ray beam. Data from the xBSM have been used to extract characteristics of beam oscillations on long and short timescales, and to make detailed studies of low-emittance tuning, intra-beam scattering, electron cloud effects, and multi-bunch instabilities.

Changes in zooplankton habitat, behavior, and acoustic scattering characteristics across glider-resolved fronts in the Southern California Current System

NASA Astrophysics Data System (ADS)

Powell, Jesse R.; Ohman, Mark D.

2015-05-01

We report cross-frontal changes in the characteristics of plankton proxy variables measured by autonomous Spray ocean gliders operating within the Southern California Current System (SCCS). A comparison of conditions across the 154 positive frontal gradients (i.e., where density of the surface layer decreased in the offshore direction) identified from six years of continuous measurements showed that waters on the denser side of the fronts typically showed higher Chl-a fluorescence, shallower euphotic zones, and higher acoustic backscatter than waters on the less dense side. Transitions between these regions were relatively abrupt. For positive fronts the amplitude of Diel Vertical Migration (DVM), inferred from a 3-beam 750 kHz acoustic Doppler profiler, increased offshore of fronts and covaried with optical transparency of the water column. Average interbeam variability in acoustic backscatter also changed across many positive fronts within 3 depth strata (0-150 m, 150-400 m, and 400-500 m), revealing a front-related change in the acoustic scattering characteristics of the assemblages. The extent of vertical stratification of distinct scattering assemblages was also more pronounced offshore of positive fronts. Depth-stratified zooplankton samples collected by Mocness nets corroborated the autonomous measurements, showing copepod-dominated assemblages and decreased zooplankton body sizes offshore and euphausiid-dominated assemblages with larger median body sizes inshore of major frontal features.

Scattering rings in optically anisotropic porous silicon

NASA Astrophysics Data System (ADS)

Oton, C. J.; Gaburro, Z.; Ghulinyan, M.; Pancheri, L.; Bettotti, P.; Negro, L. Dal; Pavesi, L.

2002-12-01

We report the observation of strongly anisotropic scattering of laser light at oblique incidence on a (100)-oriented porous silicon layer. The scattered light forms cones tangent to the incident and reflected beams. The conical pattern is caused by scattering on the vertical walls of pores, which are straight along the layer thickness. The light cone defines structured light rings onto a screen normal to the cone axis. We explain the various structures by optical anisotropy of porous silicon. For the sample under analysis, we directly measure from the ring patterns a value of Δn/nord=8% of positive birefringence.

Spatial two-photon interference in a Hong-Ou-Mandel interferometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Heonoh; Kwon, Osung; Kim, Wonsik

2006-02-15

We report the observation of the cosine modulation in the coincidence rates from a Hong-Ou-Mandel (HOM) interferometer. Spatial interference fringes are seen by minute rotations of one mirror about the vertical axis, while the beam splitter is fixed in the center position. The results show that the maximum visibility of the fringe is 0.81, and the photon pairs separated by less than 1.52 mm in the source plane are measured to be indistinguishable. It turns out that it is possible to invert the HOM dips to peaks by the rotation of the mirror.

Method for laser-based two-dimensional navigation system in a structured environment

DOEpatents

Boultinghouse, Karlan D.; Schoeneman, J. Lee; Tise, Bertice L.

1989-01-01

A low power, narrow laser beam, generated by a laser carried by a mobile vehicle, is rotated about a vertical reference axis as the vehicle navigates within a structured environment. At least three stationary retroreflector elements are located at known positions, preferably at the periphery of the structured environment, with one of the elements having a distinctive retroreflection. The projected rotating beam traverses each retroreflector in succession, and the corresponding retroreflections are received at the vehicle and focussed on a photoelectric cell to generate corresponding electrical signals. The signal caused by the distinctive retroreflection serves as an angle-measurement datum. An angle encoder coupled to the apparatus rotating the projected laser beam provides the angular separation from this datum of the lines connecting the mobile reference axis to successive retroreflectors. This real-time angular data is utilized with the known locations of the retroreflectors to trigonometrically compute using three point resection, the exact real-time location of the mobile reference axis (hence the navigating vehicle) vis-a-vis the structured environment, e.g., in terms of two-dimensional Cartesian coordinates associated with the environment.

The Effects of Optical Feedback on Polarization of Vertical Cavity Surface Emitting Lasers

DTIC Science & Technology

1993-12-01

Beam Mode TEMN Dichroic Beam Splitters (2) Manufacturer CVI Maximum Reflectance 375 mrn, 950 un Maximum Transmission 830 rnm, 910 mn Design Angle 5... beam splitter (DBS). The DBS reflects the majority of the light at the VCSEL wavelength (and passes most of the pump wavelength). A normal beamsplitter...degrees Beam Splitters Manufacturer Melles Griot Reflectancetrransnittance -50/50 Filters (2) Manufacturer Ealing Center Wavelength 880 urn, 940 mun

Monte Carlo modeling of ultrasound probes for image guided radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bazalova-Carter, Magdalena, E-mail: bazalova@uvic.ca; Schlosser, Jeffrey; Chen, Josephine

2015-10-15

Purpose: To build Monte Carlo (MC) models of two ultrasound (US) probes and to quantify the effect of beam attenuation due to the US probes for radiation therapy delivered under real-time US image guidance. Methods: MC models of two Philips US probes, an X6-1 matrix-array transducer and a C5-2 curved-array transducer, were built based on their megavoltage (MV) CT images acquired in a Tomotherapy machine with a 3.5 MV beam in the EGSnrc, BEAMnrc, and DOSXYZnrc codes. Mass densities in the probes were assigned based on an electron density calibration phantom consisting of cylinders with mass densities between 0.2 andmore » 8.0 g/cm{sup 3}. Beam attenuation due to the US probes in horizontal (for both probes) and vertical (for the X6-1 probe) orientation was measured in a solid water phantom for 6 and 15 MV (15 × 15) cm{sup 2} beams with a 2D ionization chamber array and radiographic films at 5 cm depth. The MC models of the US probes were validated by comparison of the measured dose distributions and dose distributions predicted by MC. Attenuation of depth dose in the (15 × 15) cm{sup 2} beams and small circular beams due to the presence of the probes was assessed by means of MC simulations. Results: The 3.5 MV CT number to mass density calibration curve was found to be linear with R{sup 2} > 0.99. The maximum mass densities in the X6-1 and C5-2 probes were found to be 4.8 and 5.2 g/cm{sup 3}, respectively. Dose profile differences between MC simulations and measurements of less than 3% for US probes in horizontal orientation were found, with the exception of the penumbra region. The largest 6% dose difference was observed in dose profiles of the X6-1 probe placed in vertical orientation, which was attributed to inadequate modeling of the probe cable. Gamma analysis of the simulated and measured doses showed that over 96% of measurement points passed the 3%/3 mm criteria for both probes placed in horizontal orientation and for the X6-1 probe in vertical orientation. The X6-1 probe in vertical orientation caused the highest attenuation of the 6 and 15 MV beams, which at 10 cm depth accounted for 33% and 43% decrease compared to the respective (15 × 15) cm{sup 2} open fields. The C5-2 probe in horizontal orientation, on the other hand, caused a dose increase of 10% and 53% for the 6 and 15 MV beams, respectively, in the buildup region at 0.5 cm depth. For the X6-1 probe in vertical orientation, the dose at 5 cm depth for the 3-cm diameter 6 MV and 5-cm diameter 15 MV beams was attenuated compared to the corresponding open fields to a greater degree by 65% and 43%, respectively. Conclusions: MC models of two US probes used for real-time image guidance during radiotherapy have been built. Due to the high beam attenuation of the US probes, the authors generally recommend avoiding delivery of treatment beams that intersect the probe. However, the presented MC models can be effectively integrated into US-guided radiotherapy treatment planning in cases for which beam avoidance is not practical due to anatomy geometry.« less

Design study of beam transport lines for BioLEIR facility at CERN

NASA Astrophysics Data System (ADS)

Ghithan, S.; Roy, G.; Schuh, S.

2017-09-01

The biomedical community has asked CERN to investigate the possibility to transform the Low Energy Ion Ring (LEIR) accelerator into a multidisciplinary, biomedical research facility (BioLEIR) that could provide ample, high-quality beams of a range of light ions suitable for clinically oriented, fundamental research on cell cultures and for radiation instrumentation development. The present LEIR machine uses fast beam extraction to the next accelerator in the chain, eventually leading to the Large Hadron Collider (LHC) . To provide beam for a biomedical research facility, a new slow extraction system must be installed. Two horizontal and one vertical experimental beamlines were designed for transporting the extracted beam to three experimental end-stations. The vertical beamline (pencil beam) was designed for a maximum energy of 75 MeV/u for low-energy radiobiological research, while the two horizontal beamlines could deliver up to 440 MeV/u. One horizontal beamline shall be used preferentially for biomedical experiments and shall provide pencil beam and a homogeneous broad beam, covering an area of 5 × 5 cm2 with a beam homogeneity of ±5%. The second horizontal beamline will have pencil beam only and is intended for hardware developments in the fields of (micro-)dosimetry and detector development. The minimum full aperture of the beamlines is approximately 100 mm at all magnetic elements, to accommodate the expected beam envelopes. Seven dipoles and twenty quadrupoles are needed for a total of 65 m of beamlines to provide the specified beams. In this paper we present the optical design for the three beamlines.

Wire position system to consistently measure and record the location change of girders following ground changes

NASA Astrophysics Data System (ADS)

Choi, H. J.; Lee, S. B.; Lee, H. G.; Y Back, S.; Kim, S. H.; Kang, H. S.

2017-07-01

Several parts that comprise the large scientific device should be installed and operated at the accurate three-dimensional location coordinates (X, Y, and Z) where they should be subjected to survey and alignment. The location of the aligned parts should not be changed in order to ensure that the electron beam parameters (Energy 10 GeV, Charge 200 pC, and Bunch Length 60 fs, Emittance X/Y 0.481 μm/0.256 μm) of PAL-XFEL (X-ray Free Electron Laser of the Pohang Accelerator Laboratory) remain stable and can be operated without any problems. As time goes by, however, the ground goes through uplift and subsidence, which consequently deforms building floors. The deformation of the ground and buildings changes the location of several devices including magnets and RF accelerator tubes, which eventually leads to alignment errors (∆X, ∆Y, and ∆Z). Once alignment errors occur with regard to these parts, the electron beam deviates from its course and beam parameters change accordingly. PAL-XFEL has installed the Hydrostatic Leveling System (HLS) to measure and record the vertical change of buildings and ground consistently and systematically and the Wire Position System (WPS) to measure the two dimensional changes of girders. This paper is designed to introduce the operating principle and design concept of WPS and discuss the current situation regarding installation and operation.

Hyperbolic umbilic caustics from oblate water drops with tilted illumination: Observations

NASA Astrophysics Data System (ADS)

Jobe, Oli; Thiessen, David B.; Marston, Philip L.

2017-11-01

Various groups have reported observations of hyperbolic umbilic diffraction catastrophe patterns in the far-field scattering by oblate acoustically levitated drops with symmetric illumination. In observations of that type the drop's symmetry axis is vertical and the illuminating light beam (typically an expanded laser beam) travels horizontally. In the research summarized here, scattering patterns in the primary rainbow region and drop measurements were recorded with vertically tilted laser beam illumination having a grazing angle as large as 4 degrees. The findings from these observations may be summarized as follows: (a) It remains possible to adjust the drop aspect ratio (diameter/height) = D/H so as to produce a V-shaped hyperbolic umbilic focal section (HUFS) in the far-field scattering. (b) The shift in the required D/H was typically an increase of less than 1% and was quadratic in the tilt. (c) The apex of the V-shaped HUFS was shifted vertically by an amount proportional to the tilt with a coefficient close to unity. The levitated drops had negligible up-down asymmetry. Our method of investigation should be useful for other generalized rainbows with tilted illumination.

Study for online range monitoring with the interaction vertex imaging method.

PubMed

Finck, Ch; Karakaya, Y; Reithinger, V; Rescigno, R; Baudot, J; Constanzo, J; Juliani, D; Krimmer, J; Rinaldi, I; Rousseau, M; Testa, E; Vanstalle, M; Ray, C

2017-11-21

Ion beam therapy enables a highly accurate dose conformation delivery to the tumor due to the finite range of charged ions in matter (i.e. Bragg peak (BP)). Consequently, the dose profile is very sensitive to patients anatomical changes as well as minor mispositioning, and so it requires improved dose control techniques. Proton interaction vertex imaging (IVI) could offer an online range control in carbon ion therapy. In this paper, a statistical method was used to study the sensitivity of the IVI technique on experimental data obtained from the Heidelberg Ion-Beam Therapy Center. The vertices of secondary protons were reconstructed with pixelized silicon detectors. The statistical study used the [Formula: see text] test of the reconstructed vertex distributions for a given displacement of the BP position as a function of the impinging carbon ions. Different phantom configurations were used with or without bone equivalent tissue and air inserts. The inflection points in the fall-off region of the longitudinal vertex distribution were computed using different methods, while the relation with the BP position was established. In the present setup, the resolution of the BP position was about 4-5 mm in the homogeneous phantom under clinical conditions (10 6 incident carbon ions). Our results show that the IVI method could therefore monitor the BP position with a promising resolution in clinical conditions.

Study for online range monitoring with the interaction vertex imaging method

NASA Astrophysics Data System (ADS)

Finck, Ch; Karakaya, Y.; Reithinger, V.; Rescigno, R.; Baudot, J.; Constanzo, J.; Juliani, D.; Krimmer, J.; Rinaldi, I.; Rousseau, M.; Testa, E.; Vanstalle, M.; Ray, C.

2017-12-01

Ion beam therapy enables a highly accurate dose conformation delivery to the tumor due to the finite range of charged ions in matter (i.e. Bragg peak (BP)). Consequently, the dose profile is very sensitive to patients anatomical changes as well as minor mispositioning, and so it requires improved dose control techniques. Proton interaction vertex imaging (IVI) could offer an online range control in carbon ion therapy. In this paper, a statistical method was used to study the sensitivity of the IVI technique on experimental data obtained from the Heidelberg Ion-Beam Therapy Center. The vertices of secondary protons were reconstructed with pixelized silicon detectors. The statistical study used the χ2 test of the reconstructed vertex distributions for a given displacement of the BP position as a function of the impinging carbon ions. Different phantom configurations were used with or without bone equivalent tissue and air inserts. The inflection points in the fall-off region of the longitudinal vertex distribution were computed using different methods, while the relation with the BP position was established. In the present setup, the resolution of the BP position was about 4-5 mm in the homogeneous phantom under clinical conditions (106 incident carbon ions). Our results show that the IVI method could therefore monitor the BP position with a promising resolution in clinical conditions.

Ultrafast Laser Beam Switching and Pulse Train Generation by Using Coupled Vertical-Cavity, Surface-Emitting Lasers (VCSELS)

NASA Technical Reports Server (NTRS)

Goorjian, Peter M. (Inventor); Ning, Cun-Zheng (Inventor)

2005-01-01

Ultrafast directional beam switching is achieved using coupled VCSELs. This approach is demonstrated to achieve beam switching frequencies of 40 GHz and more and switching directions of about eight degrees. This switching scheme is likely to be useful for ultrafast optical networks at frequencies much higher than achievable with other approaches.

Wavelength-scale Microlasers based on VCSEL-Photonic Crystal Architecture

DTIC Science & Technology

2015-01-20

molecular beam epitaxy , MBE). We will also assume the triangular lattice of air...Abbreviations, and Acronyms InP: indium phosphide InGaAsP: indium gallium arsenide phosphide MBE: molecular beam epiitaxy VCSEL : vertical cavity...substrates and were grown by MBE. Electron beam lithography and reactive ion etching was used to deep‐etch the holes of the PhC‐ VCSELS ,

Electron beam controlled covalent attachment of small organic molecules to graphene

NASA Astrophysics Data System (ADS)

Markevich, Alexander; Kurasch, Simon; Lehtinen, Ossi; Reimer, Oliver; Feng, Xinliang; Müllen, Klaus; Turchanin, Andrey; Khlobystov, Andrei N.; Kaiser, Ute; Besley, Elena

2016-01-01

The electron beam induced functionalization of graphene through the formation of covalent bonds between free radicals of polyaromatic molecules and C&z.dbd;C bonds of pristine graphene surface has been explored using first principles calculations and high-resolution transmission electron microscopy. We show that the energetically strongest attachment of the radicals occurs along the armchair direction in graphene to carbon atoms residing in different graphene sub-lattices. The radicals tend to assume vertical position on graphene substrate irrespective of direction of the bonding and the initial configuration. The ``standing up'' molecules, covalently anchored to graphene, exhibit two types of oscillatory motion - bending and twisting - caused by the presence of acoustic phonons in graphene and dispersion attraction to the substrate. The theoretically derived mechanisms are confirmed by near atomic resolution imaging of individual perchlorocoronene (C24Cl12) molecules on graphene. Our results facilitate the understanding of controlled functionalization of graphene employing electron irradiation as well as mechanisms of attachment of impurities via the processing of graphene nanoelectronic devices by electron beam lithography.The electron beam induced functionalization of graphene through the formation of covalent bonds between free radicals of polyaromatic molecules and C&z.dbd;C bonds of pristine graphene surface has been explored using first principles calculations and high-resolution transmission electron microscopy. We show that the energetically strongest attachment of the radicals occurs along the armchair direction in graphene to carbon atoms residing in different graphene sub-lattices. The radicals tend to assume vertical position on graphene substrate irrespective of direction of the bonding and the initial configuration. The ``standing up'' molecules, covalently anchored to graphene, exhibit two types of oscillatory motion - bending and twisting - caused by the presence of acoustic phonons in graphene and dispersion attraction to the substrate. The theoretically derived mechanisms are confirmed by near atomic resolution imaging of individual perchlorocoronene (C24Cl12) molecules on graphene. Our results facilitate the understanding of controlled functionalization of graphene employing electron irradiation as well as mechanisms of attachment of impurities via the processing of graphene nanoelectronic devices by electron beam lithography. Electronic supplementary information (ESI) available: A table showing the calculated binding energies and magnetic moments for all studied molecular radicals; details of samples preparation and characterization; time series of TEM images showing transformations of a C24Cl12 molecule on graphene under electron irradiation. See DOI: 10.1039/c5nr07539d

Beam commissioning of a superconducting rotating-gantry for carbon-ion radiotherapy

NASA Astrophysics Data System (ADS)

Iwata, Y.; Fujimoto, T.; Matsuba, S.; Fujita, T.; Sato, S.; Furukawa, T.; Hara, Y.; Mizushima, K.; Saraya, Y.; Tansho, R.; Saotome, N.; Shirai, T.; Noda, K.

2016-10-01

A superconducting rotating-gantry for carbon-ion radiotherapy was developed. This isocentric gantry can transport carbon ions having kinetic energies of between E=430 and 48 MeV/u to an isocenter over an angle of ±180°, and is further capable of performing three-dimensional raster-scanning irradiation. Construction of the entire rotating-gantry system was completed by the end of September 2015. Prior to beam commissioning, phase-space distributions of extracted carbon beams from the synchrotron were deduced by using an empirical method. In this method, phase-space distributions at the extraction channel of the synchrotron were modeled with 8 parameters, and the best parameters were determined so as to minimize a difference between the calculated and measured beam profiles by using a simplex method. Based on the phase-space distributions, beam optics through the beam-transport lines as well as the rotating gantry were designed. Since horizontal and vertical beam emittances, as extracted slowly from the synchrotron, generally differ with each other, a horizontal-vertical beam coupling would occur when the gantry rotates. Thus, the size and shape of beam spots at the isocenter should vary depending on the gantry angle. To compensate for the difference in the emittances, we employed a method to utilize multiple Coulomb scattering of the beam particles by a thin scatterer. Having compensated for the emittances and designed beam optics through the rotating gantry, beam commissioning over various combinations of gantry angles and beam energies was performed. By finely tuning the superconducting quadrupoles of the rotating gantry, we could successfully obtain the designed beam quality, which satisfies the requirements of scanning irradiation.

Coupling control and optimization at the Canadian Light Source

NASA Astrophysics Data System (ADS)

Wurtz, W. A.

2018-06-01

We present a detailed study using the skew quadrupoles in the Canadian Light Source storage ring lattice to control the parameters of a coupled lattice. We calculate the six-dimensional beam envelop matrix and use it to produce a variety of objective functions for optimization using the Multi-Objective Particle Swarm Optimization (MOPSO) algorithm. MOPSO produces a number of skew quadrupole configurations that we apply to the storage ring. We use the X-ray synchrotron radiation diagnostic beamline to image the beam and we make measurements of the vertical dispersion and beam lifetime. We observe satisfactory agreement between the measurements and simulations. These methods can be used to adjust phase space coupling in a rational way and have applications to fine-tuning the vertical emittance and Touschek lifetime and measuring the gas scattering lifetime.

The calibration of an HF radar used for ionospheric research

NASA Astrophysics Data System (ADS)

From, W. R.; Whitehead, J. D.

1984-02-01

The HF radar on Bribie Island, Australia, uses crossed-fan beams produced by crossed linear transmitter and receiver arrays of 10 elements each to simulate a pencil beam. The beam points vertically when all the array elements are in phase, and is steerable by up to 20 deg off vertical at the central one of the three operating frequencies. Phase and gain changes within the transmitters and receivers are compensated for by an automatic system of adjustment. The 10 transmitting antennas are, as nearly as possible, physically identical as are the 10 receiving antennas. Antenna calibration using high flying aircraft or satellites is not possible. A method is described for using the ionospheric reflections to measure the polar diagram and also to correct for errors in the direction of pointing.

High yield growth of patterned vertically aligned carbon nanotubes using inkjet-printed catalyst.

PubMed

Beard, James D; Stringer, Jonathan; Ghita, Oana R; Smith, Patrick J

2013-10-09

This study reports on the fabrication of vertically aligned carbon nanotubes localized at specific sites on a growth substrate by deposition of a nanoparticle suspension using inkjet printing. Carbon nanotubes were grown with high yield as vertically aligned forests to a length of approximately 400 μm. The use of inkjet printing for catalyst fabrication considerably improves the production rate of vertically aligned patterned nanotube forests compared with conventional patterning techniques, for example, electron beam lithography or photolithography.

An embeddable optical strain gauge based on a buckled beam.

PubMed

Du, Yang; Chen, Yizheng; Zhu, Chen; Zhuang, Yiyang; Huang, Jie

2017-11-01

We report, for the first time, a low cost, compact, and novel mechanically designed extrinsic Fabry-Perot interferometer (EFPI)-based optical fiber sensor with a strain amplification mechanism for strain measurement. The fundamental design principle includes a buckled beam with a coated gold layer, mounted on two grips. A Fabry-Perot cavity is produced between the buckled beam and the endface of a single mode fiber (SMF). A ceramic ferrule is applied for supporting and orienting the SMF. The principal sensor elements are packaged and protected by two designed metal shells. The midpoint of the buckled beam will experience a deflection vertically when the beam is subjected to a horizontally/axially compressive displacement. It has been found that the vertical deflection of the beam at midpoint can be 6-17 times larger than the horizontal/axial displacement, which forms the basis of a strain amplification mechanism. The user-configurable buckling beam geometry-based strain amplification mechanism enables the strain sensor to achieve a wide range of strain measurement sensitivities. The designed EFPI was used to monitor shrinkage of a square brick of mortar. The strain was measured during the drying/curing stage. We envision that it could be a good strain sensor to be embedded in civil materials/structures under a harsh environment for a prolonged period of time.

An embeddable optical strain gauge based on a buckled beam

NASA Astrophysics Data System (ADS)

Du, Yang; Chen, Yizheng; Zhu, Chen; Zhuang, Yiyang; Huang, Jie

2017-11-01

We report, for the first time, a low cost, compact, and novel mechanically designed extrinsic Fabry-Perot interferometer (EFPI)-based optical fiber sensor with a strain amplification mechanism for strain measurement. The fundamental design principle includes a buckled beam with a coated gold layer, mounted on two grips. A Fabry-Perot cavity is produced between the buckled beam and the endface of a single mode fiber (SMF). A ceramic ferrule is applied for supporting and orienting the SMF. The principal sensor elements are packaged and protected by two designed metal shells. The midpoint of the buckled beam will experience a deflection vertically when the beam is subjected to a horizontally/axially compressive displacement. It has been found that the vertical deflection of the beam at midpoint can be 6-17 times larger than the horizontal/axial displacement, which forms the basis of a strain amplification mechanism. The user-configurable buckling beam geometry-based strain amplification mechanism enables the strain sensor to achieve a wide range of strain measurement sensitivities. The designed EFPI was used to monitor shrinkage of a square brick of mortar. The strain was measured during the drying/curing stage. We envision that it could be a good strain sensor to be embedded in civil materials/structures under a harsh environment for a prolonged period of time.

The larynx ruler to measure height and profile of vocal folds: a proof of concept.

PubMed

Desuter, Gauthier; Mertens, Benjamin; Delchambre, Alain; van Lith-Bijl, Julie; van Benthem, Peter Paul; Sjögren, Elisabeth

2017-01-01

Glottic leakage during phonation is a direct consequence of unilateral vocal fold (VF) paralysis. This air leakage can be in the horizontal plane and in the vertical plane. Presently, there is no easily applicable medical device allowing noninvasive, office-based measurement of the relative vertical position of the VFs. The larynx ruler (LR) is a laser-based measuring device that could meet the previously stated need, using a flexible endoscope. This study represents a proof of concept regarding the use of the LR in assessing VF relative positions in the vertical plane. One fresh male human cadaver larynx, free of neurologic and anatomic disease, was explored with the LR system through the operative channel of a flexible gastroenterology video-endoscope. The tip of the video-endoscope was located in the laryngeal vestibule. The right crico-arytenoid joint was posteriorly disarticulated. Tilting of the VF was obtained by pulling or pushing the arytenoid cartilage with a mosquito forceps fixed to the stump of the previously sectioned superior tip of the posterior crico-arytenoid muscle allowing anterior and posterior tilting of the arytenoid cartilage in order to induce an elevation or a depression of the VF process. Ten "push" and ten "pull" sessions were performed. The distance from the tip of the video-endoscope to each illuminated pixel of the laser beam was recorded. The level difference between the left and right VFs was measured for each recording. Data provided by the LR were consistently in accordance with the movements applied on the VFs. The accuracy of 0.2 mm of the LR is compatible with the envisioned applications for the human larynx. The LR system represents a feasible technique to evaluate respective vertical position of VFs in the human larynx. Technical limitations were identified that will require improvements before experimental use on human beings.

Design and Characterization of Optically Pumped Vertical Cavity Surface Emitting Lasers

DTIC Science & Technology

1992-12-01

technology to make VCSELs (e.g. Molecular Beam Epitaxy (MBE) and Metal-Organic Chemical Vapor Deposition (MOCVD)) motivated the research in this area over the...Resistances for Current Injected VCSELs 3-14 4.1. Equipment Configuration used for Output Beam Characterization . . . 4-1 4.2. Optical Pump Beam and Focusing...pursued over the past few years because VCSELs have ad- ditional inherent advantages. The VCSEL design exhibits better exit beam quality, is of smaller

Molecular beam epitaxy growth method for vertical-cavity surface-emitting laser resonators based on substrate thermal emission

NASA Astrophysics Data System (ADS)

Talghader, J. J.; Hadley, M. A.; Smith, J. S.

1995-12-01

A molecular beam epitaxy growth monitoring method is developed for distributed Bragg reflectors and vertical-cavity surface-emitting laser (VCSEL) resonators. The wavelength of the substrate thermal emission that corresponds to the optical cavity resonant wavelength is selected by a monochromator and monitored during growth. This method allows VCSEL cavities of arbitrary design wavelength to be grown with a single control program. This letter also presents a theoretical model for the technique which is based on transmission matrices and simple thermal emission properties. Demonstrated reproducibility of the method is well within 0.1%.

Experience with Round Beam Operation at The Advanced Photon Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, A.; Emery, L.; Sajaev, V.

2015-01-01

Very short Touschek lifetime becomes a common issue for next-generation ultra-low emittance storage ring light sources. In order to reach a longer beamlifetime, such amachine often requires operating with a vertical-to-horizontal emittance ratio close to an unity, i.e. a “round beam”. In tests at the APS storage ring, we determined how a round beam can be reached experimentally. Some general issues, such as beam injection, optics measurement and corrections, and orbit correction have been tested also. To demonstrate that a round beam was achieved, the beam size ratio is calibrated using beam lifetime measurement.

Optimized coupling of cold atoms into a fiber using a blue-detuned hollow-beam funnel

NASA Astrophysics Data System (ADS)

Poulin, Jerome; Light, Philip S.; Kashyap, Raman; Luiten, Andre N.

2011-11-01

We theoretically investigate the process of coupling cold atoms into the core of a hollow-core photonic-crystal optical fiber using a blue-detuned Laguerre-Gaussian beam. In contrast to the use of a red-detuned Gaussian beam to couple the atoms, the blue-detuned hollow beam can confine cold atoms to the darkest regions of the beam, thereby minimizing shifts in the internal states and making the guide highly robust to heating effects. This single optical beam is used as both a funnel and a guide to maximize the number of atoms into the fiber. In the proposed experiment, Rb atoms are loaded into a magneto-optical trap (MOT) above a vertically oriented optical fiber. We observe a gravito-optical trapping effect for atoms with high orbital momentum around the trap axis, which prevents atoms from coupling to the fiber: these atoms lack the kinetic energy to escape the potential and are thus trapped in the laser funnel indefinitely. We find that by reducing the dipolar force to the point at which the trapping effect just vanishes, it is possible to optimize the coupling of atoms into the fiber. Our simulations predict that by using a low-power (2.5 mW) and far-detuned (300 GHz) Laguerre-Gaussian beam with a 20-μm-radius core hollow fiber, it is possible to couple 11% of the atoms from a MOT 9 mm away from the fiber. When the MOT is positioned farther away, coupling efficiencies over 50% can be achieved with larger core fibers.

Cone-Beam Computed Tomography Evaluation of Horizontal and Vertical Dimensional Changes in Buccal Peri-Implant Alveolar Bone and Soft Tissue: A 1-Year Prospective Clinical Study.

PubMed

Kaminaka, Akihiro; Nakano, Tamaki; Ono, Shinji; Kato, Tokinori; Yatani, Hirofumi

2015-10-01

This study evaluated changes in the horizontal and vertical dimensions of the buccal alveolar bone and soft tissue over a 1-year period following implant prosthesis. Thirty-three participants with no history of guided bone regeneration or soft tissue augmentation underwent dental implant placement with different types of connections. The dimensions of the buccal alveolar bone and soft tissue were evaluated immediately and at 1 year after prosthesis from reconstructions of cross-sectional cone-beam computed tomography images. The vertical and horizontal loss of buccal bone and soft tissue around implants with conical connections were lower than around those with external or internal connections. Statistically significant negative correlations were observed between initial horizontal bone thickness and changes in vertical bone and soft tissue height (p < .05), and between initial horizontal soft tissue thickness and the change in vertical soft tissue height (p < .05). Implants with a conical connection preserve peri-implant alveolar bone and soft tissue more effectively than other connection types. Furthermore, the initial buccal alveolar bone and soft tissue thickness around the implant platform may influence their vertical dimensional changes at 1 year after implant prosthesis. © 2014 Wiley Periodicals, Inc.

Three-dimensional aspects of the shrinking phenomenon of ArF resist

NASA Astrophysics Data System (ADS)

Laufer, Ido; Eytan, Giora E.; Dror, Ophir

2002-07-01

Previous studies of the interaction of electron beams with different types of ArF resists have shown the undesired phenomenon of the resist shrinkage. The lateral component of this shrinkage has been detected and quantified easily by SEM CD measurements. However, the vertical extent of this phenomenon has to date remained unknown. In this work we present measurements of the changes in height and sidewall angles of an ArF line by using a new e-beam tilting ability of the Vera SEM 3D. The 3D measurement results show that the height of the line shrinks in similar proportions to the top and bottom CDs, with a difference in the magnitude. Due to higher penetration depth of the e-beam on the top of the line than on the sidewall, the vertical shrinkage reaches steady state more rapidly than the lateral shrinkage. We also found a slight reduction in sidewall angle, which is less than one degree even under high e-beam exposure.

Methods and apparatus for vertical coupling from dielectric waveguides

DOEpatents

Yaacobi, Ami; Cordova, Brad Gilbert

2014-06-17

A frequency-chirped nano-antenna provides efficient sub-wavelength vertical emission from a dielectric waveguide. In one example, this nano-antenna includes a set of plasmonic dipoles on the opposite side of a SiYV.sub.4 waveguide from a ground plane. The resulting structure, which is less than half a wavelength long, emits a broadband beam (e.g., >300 nm) that can be coupled into an optical fiber. In some embodiments, a diffractive optical element with unevenly shaped regions of high- and low-index dielectric material collimates the broadband beam for higher coupling efficiency. In some cases, a negative lens element between the nano-antenna and the diffractive optical element accelerates the emitted beam's divergence (and improves coupling efficiency), allowing for more compact packaging. Like the diffractive optical element, the negative lens element includes unevenly shaped regions of high- and low-index dielectric material that can be designed to compensate for aberrations in the beam emitted by the nano-antenna.

Minimization of transverse beam-emittance growth in the 90-degree bending section of the RAON rare-isotope accelerator

NASA Astrophysics Data System (ADS)

Oh, B. H.; Yoon, M.

2016-11-01

The major contribution of the transverse beam emittance growth (EG) in a RAON heavy-ion accelerator comes from the bending section, which consists of a charge-stripping section, a matching section, and a charge-selection section in sequence. In this paper, we describe our research to minimize the two-dimensional EG in the 90-degree bending section of the RAON currently being developed in Korea. The EG minimization was achieved with the help of multi-objective genetic algorithms and the simplex method. We utilized those algorithms to analyze the 90-degree bending section in a driver linac for the in-flight fragmentation system. Horizontal and vertical EGs were limited to below 10 % in the bending section by adjustment of the transverse beam optics upstream from the charge-stripping section, redesign of the charge-selection section, and optimization of the vertical beam optics at the entrance of a charge-selection section.

Resonances and vibrations in an elevator cable system due to boundary sway

NASA Astrophysics Data System (ADS)

Gaiko, Nick V.; van Horssen, Wim T.

2018-06-01

In this paper, an analytical method is presented to study an initial-boundary value problem describing the transverse displacements of a vertically moving beam under boundary excitation. The length of the beam is linearly varying in time, i.e., the axial, vertical velocity of the beam is assumed to be constant. The bending stiffness of the beam is assumed to be small. This problem may be regarded as a model describing the lateral vibrations of an elevator cable excited at its boundaries by the wind-induced building sway. Slow variation of the cable length leads to a singular perturbation problem which is expressed in slowly changing, time-dependent coefficients in the governing differential equation. By providing an interior layer analysis, infinitely many resonance manifolds are detected. Further, the initial-boundary value problem is studied in detail using a three-timescales perturbation method. The constructed formal approximations of the solutions are in agreement with the numerical results.

An alternative approach to extruding a vertically impacted lower third molar using an orthodontic miniscrew: A case report with cone-beam CT follow-up

PubMed Central

No-Cortes, Juliana; Cavalcanti, Marcelo Gusmão Paraíso; Arita, Emiko Saito

2014-01-01

One of the most common oral surgical procedures is the extraction of the lower third molar (LTM). Postoperative complications such as paresthesia due to inferior alveolar nerve (IAN) injury are commonly observed in cases of horizontal and vertical impaction. The present report discusses a case of a vertically impacted LTM associated with a dentigerous cyst. An intimate contact between the LTM roots and the mandibular canal was observed on a panoramic radiograph and confirmed with cone-beam computed tomographic (CBCT) cross-sectional cuts. An orthodontic miniscrew was then used to extrude the LTM prior to its surgical removal in order to avoid the risk of inferior alveolar nerve injury. CBCT imaging follow-up confirmed the success of the LTM orthodontic extrusion. PMID:24944969

An alternative approach to extruding a vertically impacted lower third molar using an orthodontic miniscrew: A case report with cone-beam CT follow-up.

PubMed

Cortes, Arthur Rodriguez Gonzalez; No-Cortes, Juliana; Cavalcanti, Marcelo Gusmão Paraíso; Arita, Emiko Saito

2014-06-01

One of the most common oral surgical procedures is the extraction of the lower third molar (LTM). Postoperative complications such as paresthesia due to inferior alveolar nerve (IAN) injury are commonly observed in cases of horizontal and vertical impaction. The present report discusses a case of a vertically impacted LTM associated with a dentigerous cyst. An intimate contact between the LTM roots and the mandibular canal was observed on a panoramic radiograph and confirmed with cone-beam computed tomographic (CBCT) cross-sectional cuts. An orthodontic miniscrew was then used to extrude the LTM prior to its surgical removal in order to avoid the risk of inferior alveolar nerve injury. CBCT imaging follow-up confirmed the success of the LTM orthodontic extrusion.

First Experiments with the Polarized Internal Gas Target (PIT) at ANKE/COSY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engels, R.; Lorentz, B.; Prasuhn, D.

2008-02-06

For future few-nucleon interaction studies with polarized beams and targets at COSY-Juelich, a polarized internal storage-cell gas target was implemented at the magnet spectrometer ANKE in summer 2005. First commissioning of the polarized Atomic Beam Source (ABS) at ANKE was carried out and some improvements of the system have been done. Storage-cell tests to determine the COSY beam dimensions have been performed. Electron cooling combined with stacking and stochastic cooling have been studied. Experiments with N{sub 2} gas in the storage cell to simulate the background produced by beam interaction with the aluminum cell walls were performed to investigate themore » beam heating by the target gas. The analysis of the d-vector p-vector {yields}dp and d-vector p-vector{yields}(dp{sub sp}){pi}{sup 0} reactions showed that events from the extended target can be clearly identified in the ANKE detector system.The polarization of the atomic beam of the ABS, positioned close to the strong dipole magnet D2 of ANKE, was tuned with a Lamb-shift polarimeter (LSP) beneath the target chamber. With use of the known analyzing powers of the quasi-free np{yields}d{pi}{sup 0} reaction, the polarization in the storage cell was measured to be Q{sub y} = 0.79{+-}0.07 in the vertical stray field of the D2 magnet acting as a holding field. The achieved target thickness was 2x10{sup 13} atoms/cm{sup 2} for one hyperfine state populated in the ABS beam only. With a COSY beam intensity of 6x10{sup 9} stored polarized deuterons in the ring, the luminosity for double polarized experiments was 1x10{sup 29} cm{sup -2} s{sup -1}.« less

All Ultra-High Vacuum In-Situ Growth & Processing Approaches to Realization of Semiconductor Nanostructure Arrays

DTIC Science & Technology

1997-05-15

Quantum Box/Dot, Strained Epitaxy , 3D islands, Patterned Substrates, Molecular Beam Epitaxy Focused Ion Beam , In-Situ Processing, Quantum Box Lasers...Grown on Planar and Patterned GaAs(100) Substrates by Molecular Beam Epitaxy ", J. Vac. Sei. Technol. B13, 642(1995) 5. A. Madhukar, P. Chen, Q. Xie...Formation and Vertical Self-Organization on GaAs(lOO) via Molecular Beam Epitaxy ", Paper presented at MRS Spring 󈨣 Meeting (Apr. 17-21, 1995, San

Data analysis of photon beam position at PLS-II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ko, J.; Shin, S., E-mail: tlssh@postech.ac.kr; Huang, Jung-Yun

In the third generation light source, photon beam position stability is critical issue on user experiment. Generally photon beam position monitors have been developed for the detection of the real photon beam position and the position is controlled by feedback system in order to keep the reference photon beam position. In the PLS-II, photon beam position stability for front end of particular beam line, in which photon beam position monitor is installed, has been obtained less than rms 1μm for user service period. Nevertheless, detail analysis for photon beam position data in order to demonstrate the performance of photon beammore » position monitor is necessary, since it can be suffers from various unknown noises. (for instance, a back ground contamination due to upstream or downstream dipole radiation, undulator gap dependence, etc.) In this paper, we will describe the start to end study for photon beam position stability and the Singular Value Decomposition (SVD) analysis to demonstrate the reliability on photon beam position data.« less

Analysis and control of the photon beam position at PLS-II

PubMed Central

Ko, J.; Kim, I.-Y.; Kim, C.; Kim, D.-T.; Huang, J.-Y.; Shin, S.

2016-01-01

At third-generation light sources, the photon beam position stability is a critical issue for user experiments. In general, photon beam position monitors are developed to detect the real photon beam position, and the position is controlled by a feedback system in order to maintain the reference photon beam position. At Pohang Light Source II, a photon beam position stability of less than 1 µm r.m.s. was achieved for a user service period in the beamline, where the photon beam position monitor is installed. Nevertheless, a detailed analysis of the photon beam position data was necessary in order to ensure the performance of the photon beam position monitor, since it can suffer from various unknown types of noise, such as background contamination due to upstream or downstream dipole radiation, and undulator gap dependence. This paper reports the results of a start-to-end study of the photon beam position stability and a singular value decomposition analysis to confirm the reliability of the photon beam position data. PMID:26917132

An Orbit And Dispersion Correction Scheme for the PEP II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, Y.; Donald, M.; Shoaee, H.

2011-09-01

To achieve optimum luminosity in a storage ring it is vital to control the residual vertical dispersion. In the original PEP storage ring, a scheme to control the residual dispersion function was implemented using the ring orbit as the controlling element. The 'best' orbit not necessarily giving the lowest vertical dispersion. A similar scheme has been implemented in both the on-line control code and in the simulation code LEGO. The method involves finding the response matrices (sensitivity of orbit/dispersion at each Beam-Position-Monitor (BPM) to each orbit corrector) and solving in a least squares sense for minimum orbit, dispersion function ormore » both. The optimum solution is usually a subset of the full least squares solution. A scheme of simultaneously correcting the orbits and dispersion has been implemented in the simulation code and on-line control system for PEP-II. The scheme is based on the eigenvector decomposition method. An important ingredient of the scheme is to choose the optimum eigenvectors that minimize the orbit, dispersion and corrector strength. Simulations indicate this to be a very effective way to control the vertical residual dispersion.« less

Finnish Meteorological Institute Doppler Lidar

DOE Data Explorer

Ewan OConnor

2015-03-27

This doppler lidar system provides co-polar and cross polar attenuated backscatter coefficients,signal strength, and doppler velocities in the cloud and in the boundary level, including uncertainties for all parameters. Using the doppler beam swinging DBS technique, and Vertical Azimuthal Display (VAD) this system also provides vertical profiles of horizontal winds.

7. Close view of the lower portion of vertical sign ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. Close view of the lower portion of vertical sign with the letters "A-G-O" after removal from theatre (Note: the steel I-beam was inserted and sheet metal side panels taken off to facilitate removal from theatre - Chicago Theater, 175 North State Street, Chicago, Cook County, IL

Dynamic characteristics of a novel damped outrigger system

NASA Astrophysics Data System (ADS)

Tan, Ping; Fang, Chuangjie; Zhou, Fulin

2014-06-01

This paper presents exact analytical solutions for a novel damped outrigger system, in which viscous dampers are vertically installed between perimeter columns and the core of a high-rise building. An improved analytical model is developed by modeling the effect of the damped outrigger as a general rotational spring acting on a Bernoulli-Euler beam. The equivalent rotational spring stiffness incorporating the combined effects of dampers and axial stiffness of perimeter columns is derived. The dynamic stiffness method (DSM) is applied to formulate the governing equation of the damped outrigger system. The accuracy and efficiency are verified in comparison with those obtained from compatibility equations and boundary equations. Parametric analysis of three non-dimensional factors is conducted to evaluate the influences of various factors, such as the stiffness ratio of the core to the beam, position of the damped outrigger, and the installed damping coefficient. Results show that the modal damping ratio is significantly influenced by the stiffness ratio of the core to the column, and is more sensitive to damping than the position of the damped outrigger. The proposed analytical model in combination with DSM can be extended to the study of structures with more outriggers.

A Low Temperature Scanning Force Microscope with a Vertical Cantilever and Interferometric Detection Scheme

NASA Astrophysics Data System (ADS)

Kim, Jeehoon; Williams, T. L.; Chu, Sang Lin; Korre, Hasan; Chalfin, Max; Hoffman, J. E.

2008-03-01

We have developed a fiber-optic interferometry system with a vertical cantilever for scanning force microscopy. A lens, mounted on a Pan-type walker, was used to collect the interference signal in the cavity between the cantilever and the single mode fiber. This vertical geometry has several advantages: (1) it is directly sensitive to lateral forces; (2) low spring constant vertical cantilevers may allow increased force sensitivity by solving the ``snap-in'' problem that occurs with soft horizontal cantilevers. We have sharpened vertical cantilevers by focused ion beam (FIB), achieving a tip radius of 20 nm. We will show test results of a magnetic force microscope (MFM) with this vertical cantilever system.

Navier-Stokes simulation of plume/Vertical Launching System interaction flowfields

NASA Astrophysics Data System (ADS)

York, B. J.; Sinha, N.; Dash, S. M.; Anderson, L.; Gominho, L.

1992-01-01

The application of Navier-Stokes methodology to the analysis of Vertical Launching System/missile exhaust plume interactions is discussed. The complex 3D flowfields related to the Vertical Launching System are computed utilizing the PARCH/RNP Navier-Stokes code. PARCH/RNP solves the fully-coupled system of fluid, two-equation turbulence (k-epsilon) and chemical species equations via the implicit, approximately factored, Beam-Warming algorithm utilizing a block-tridiagonal inversion procedure.

JSEP Fellowship

DTIC Science & Technology

1993-06-28

entitled "MBE Grown Microcavities for Optoelectronic Devices." In the dissertation work,1 the precision of molecular - beam epitaxy (MBE) is taken...Layers For Surface Normal Optoelectronic Devices," North American Conference on Molecular Beam Epitaxy , Ottawa, Canada, October 12-14, 1992, to be...8. C. Lei, T. J. Rogers, D. G. Deppe, and B. G. Streetman, "InGaAs-GaAs Quantum Well Vertical-Cavity Surface-Emitting Laser Using Molecular Beam

Beam line shielding calculations for an Electron Accelerator Mo-99 production facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mocko, Michal

2016-05-03

The purpose of this study is to evaluate the photon and neutron fields in and around the latest beam line design for the Mo-99 production facility. The radiation dose to the beam line components (quadrupoles, dipoles, beam stops and the linear accelerator) are calculated in the present report. The beam line design assumes placement of two cameras: infra red (IR) and optical transition radiation (OTR) for continuous monitoring of the beam spot on target during irradiation. The cameras will be placed off the beam axis offset in vertical direction. We explored typical shielding arrangements for the cameras and report themore » resulting neutron and photon dose fields.« less

Vertical laser beam propagation through the troposphere

NASA Technical Reports Server (NTRS)

Minott, P. O.; Bufton, J. L.; Schaefer, W. H.; Grolemund, D. A.

1974-01-01

The characteristics of the earth's atmosphere and its effects upon laser beams was investigated in a series of balloon borne, optical propagation experiments. These experiments were designed to simulate the space to ground laser link. An experiment to determine the amplitude fluctuation, commonly called scintillation, caused by the atmosphere was described.

Lasers for Training Devices.

ERIC Educational Resources Information Center

Fuller, C. A.

A breadboard model of a laser display system is described in detail and its operating procedure is outlined. The system consists of: a Model 52 argon krypton ion laser and power supply; an optical breadboard comprising a pocket cell light modulator, a galvonmeter beam deflector for vertical scanning, a unique multiple reflection beam steerer for…

Results of using the NSTX-U Plasma Control System for scenario development

NASA Astrophysics Data System (ADS)

Boyer, M. D.; Battaglia, D. J.; Gates, D. A.; Gerhardt, S.; Menard, J.; Mueller, D.; Myers, C. E.; Ferron, J.; Sabbagh, S.; NSTX-U Team

2016-10-01

To best use the new capabilities of NSTX-U (e.g., higher toroidal field and additional, more distributed heating and current drive sources) and to achieve the operational goals of the program, major upgrades to the Plasma Control System have been made. These include improvements to vertical control, real-time equilibrium reconstruction, and plasma boundary shape control and the addition of flexible algorithms for beam modulation and gas injection to control the upgraded actuators in real-time, enabling their use in algorithms for stored energy and profile control. Control system commissioning activities have so far focused on vertical position and shape control. The upgraded controllers have been used to explore the vertical stability limits in inner wall limited and diverted discharges, and control of X-point and strike point locations has been demonstrated and is routinely used. A method for controlling the mid-plane inner gap, a challenge for STs, has also been added to improve reproducible control of diverted discharges. A supervisory shutdown handling algorithm has also been commissioned to ramp the plasma down and safely turn off actuators after an event such as loss of vertical control. Use of the upgrades has contributed to achieving 1MA, 0.65T scenarios with greater than 1s pulse length. Work supported by U.S. D.O.E. Contract No. DE-AC02-09CH11466.

Development of Biological Acoustic Impedance Microscope and its Error Estimation

NASA Astrophysics Data System (ADS)

Hozumi, Naohiro; Nakano, Aiko; Terauchi, Satoshi; Nagao, Masayuki; Yoshida, Sachiko; Kobayashi, Kazuto; Yamamoto, Seiji; Saijo, Yoshifumi

This report deals with the scanning acoustic microscope for imaging cross sectional acoustic impedance of biological soft tissues. A focused acoustic beam was transmitted to the tissue object mounted on the "rear surface" of plastic substrate. A cerebellum tissue of rat and a reference material were observed at the same time under the same condition. As the incidence is not vertical, not only longitudinal wave but also transversal wave is generated in the substrate. The error in acoustic impedance assuming vertical incidence was estimated. It was proved that the error can precisely be compensated, if the beam pattern and acoustic parameters of coupling medium and substrate had been known.

A Forest of Sub-1.5-nm-wide Single-Walled Carbon Nanotubes over an Engineered Alumina Support

NASA Astrophysics Data System (ADS)

Yang, Ning; Li, Meng; Patscheider, Jörg; Youn, Seul Ki; Park, Hyung Gyu

2017-04-01

A precise control of the dimension of carbon nanotubes (CNTs) in their vertical array could enable many promising applications in various fields. Here, we demonstrate the growth of vertically aligned, single-walled CNTs (VA-SWCNTs) with diameters in the sub-1.5-nm range (0.98 ± 0.24 nm), by engineering a catalyst support layer of alumina via thermal annealing followed by ion beam treatment. We find out that the ion beam bombardment on the alumina allows the growth of ultra-narrow nanotubes, whereas the thermal annealing promotes the vertical alignment at the expense of enlarged diameters; in an optimal combination, these two effects can cooperate to produce the ultra-narrow VA-SWCNTs. According to micro- and spectroscopic characterizations, ion beam bombardment amorphizes the alumina surface to increase the porosity, defects, and oxygen-laden functional groups on it to inhibit Ostwald ripening of catalytic Fe nanoparticles effectively, while thermal annealing can densify bulk alumina to prevent subsurface diffusion of the catalyst particles. Our findings contribute to the current efforts of precise diameter control of VA-SWCNTs, essential for applications such as membranes and energy storage devices.

Convection currents in a water calorimeter.

PubMed

Schulz, R J; Weinhous, M S

1985-10-01

A flexible, temperature-regulated water calorimeter has been constructed containing two pairs of thermistor sensors at depths of 6.23 and 10.0 cm. It may be irradiated by vertical or horizontal beams, and operated at temperatures in the range from 3 to 40 degrees C. When irradiated at 30 degrees C with a vertically downward 19 MeV electron beam, the responses of the proximal and midline thermistors were in accordance with the depth-dose curve. When irradiated horizontally, the initial patterns of temperature rise were the same, but after about 30 s (4 Gy) the rate of temperature rise decreased at the proximal thermistors and increased at the midline thermistors. Shortly after irradiation, the temperature curve and increased at the midline thermistors. Shortly after irradiation, the temperature curve of the midline thermistors crossed that for the proximal thermistors, a pattern that suggested the presence of convection currents. To test this hypothesis, the calorimeter was operated at 4 degrees C. The temperature patterns for horizontal irradiation became the same as those obtained with vertical beams, thus demonstrating the production of convection currents in water at a temperature of 30 degrees C for temperature gradients as small as 10(-3) degrees C cm-1.

Mu2e-II Injection from PIP-II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neuffer, David

We discuss injection of 800 MeV proton beam from PIP-II into the production target for Mu2e-II, assuming a targeting and μ production scenario similar to mu2e. The incoming beam trajectory must be modified from the mu2e parameters to match the focusing fields. Adding a vertical deflection at injection enables the injected beam to reach the target. Other differences from the mu2e system must be considered, including changes in the target structure, the radiation shielding and beam dump/absorber. H- beam should be stripped to p+. Other variations are discussed.

Experimental evidence of ion-induced instabilities in the NSLS-II storage ring

DOE PAGES

Cheng, Weixing; Li, Yongjun; Podobedov, Boris

2017-03-12

Fast ion instability has been identified as one of the most prominent instabilities in the recently constructed NSLS-II storage ring at Brookhaven National Laboratory. At a relatively low beam current (~ 25 mA) multi-bunch fills, ion-induced instabilities have already been observed during the early stages of machine commissioning. At present user operation with 250 mA in ~1000 bunches, the fast ion still remains the dominant instability, even after months of vacuum conditioning at high current. Ion-induced dipole motions of the electron beam have been suppressed using the transverse bunch-by-bunch (BxB) feedback system. However other adverse effects of this instability, suchmore » as the vertical beam size increase along the bunch train cannot be cured by the feedback system. Therefore, to achieve the NSLS-II design current of 500 mA while maintaining a small vertical beam emittance, it is important to further understand the fast ion instability and develop mitigation techniques. This paper reports on a series of ion-instability observations at various fill patterns and beam currents using start-of-art NSLS-II diagnostic tools.« less

Experimental evidence of ion-induced instabilities in the NSLS-II storage ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Weixing; Li, Yongjun; Podobedov, Boris

Fast ion instability has been identified as one of the most prominent instabilities in the recently constructed NSLS-II storage ring at Brookhaven National Laboratory. At a relatively low beam current (~ 25 mA) multi-bunch fills, ion-induced instabilities have already been observed during the early stages of machine commissioning. At present user operation with 250 mA in ~1000 bunches, the fast ion still remains the dominant instability, even after months of vacuum conditioning at high current. Ion-induced dipole motions of the electron beam have been suppressed using the transverse bunch-by-bunch (BxB) feedback system. However other adverse effects of this instability, suchmore » as the vertical beam size increase along the bunch train cannot be cured by the feedback system. Therefore, to achieve the NSLS-II design current of 500 mA while maintaining a small vertical beam emittance, it is important to further understand the fast ion instability and develop mitigation techniques. This paper reports on a series of ion-instability observations at various fill patterns and beam currents using start-of-art NSLS-II diagnostic tools.« less

Laser-assisted simultaneous transfer and patterning of vertically aligned carbon nanotube arrays on polymer substrates for flexible devices.

PubMed

In, Jung Bin; Lee, Daeho; Fornasiero, Francesco; Noy, Aleksandr; Grigoropoulos, Costas P

2012-09-25

We demonstrate a laser-assisted dry transfer technique for assembling patterns of vertically aligned carbon nanotube arrays on a flexible polymeric substrate. A laser beam is applied to the interface of a nanotube array and a polycarbonate sheet in contact with one another. The absorbed laser heat promotes nanotube adhesion to the polymer in the irradiated regions and enables selective pattern transfer. A combination of the thermal transfer mechanism with rapid direct writing capability of focused laser beam irradiation allows us to achieve simultaneous material transfer and direct micropatterning in a single processing step. Furthermore, we demonstrate that malleability of the nanotube arrays transferred onto a flexible substrate enables post-transfer tailoring of electric conductance by collapsing the aligned nanotubes in different directions. This work suggests that the laser-assisted transfer technique provides an efficient route to using vertically aligned nanotubes as conductive elements in flexible device applications.

Airbreathing Laser Propulsion Experiments with 1 {mu}m Terawatt Pharos III Laser: Part 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Myrabo, L. N.; Lyons, P. W.; Jones, R. A.

This basic research study examines the physics of airbreathing laser propulsion at the extreme flux range of 1-2x10{sup 11} W/cm{sup 2}--within the air breakdown threshold for l {mu}m radiation--using the terawatt PHAROS III neodymium-glass pulsed laser. Six different experimental setups were tested using a 34 mm line focus with 66 {mu}m focal waist, positioned near the flat impulse surface. The first campaign investigated impulse generation with the beam oriented almost normal to the target surface, with energies ranging from 23 to 376 J, and pulses of 5 to 30 ns FWHM. Air breakdown/ plasma dynamics were diagnosed with GOI camerasmore » and color photography. Laser generated impulse was quantified with both vertical pendulums and piezoelectric pressure transducers using the standard performance metric, C{sub M}--the momentum coupling coefficient. Part 1 of this 2-part paper covers Campaign no. 1 results including laser plasma diagnostics, pressure gage and vertical pendulum data.« less

Observation of excess flux for negative cosmic ray penetrating particles in bubble chamber "SKAT" for momentum range (30GeV/c

NASA Astrophysics Data System (ADS)

Bazhutov, Yu. N.; Baranov, D. S.

2001-08-01

There are presented the first results of the new heavy stable cosmic ray particles search in the bubble chamber "SKAT" (450 x 160 x 90 cm3 ), which was exposed in the neutrino beam of Serpukhov Accelerator during 1976 - 1992 years and was viewed along the horizontal direction so as the magnet field direction (MDM > 150 GeV/c). From looking over 1,270 stills (1 roll for April 23, 1979) it was selected 757 tracks of cosmic ray particles with zenith angle θ < 45°, track length - L > 50 cm and momentum P>2.0GeV/c. From this events there were constructed momentum spectrums for both negative and positive vertical cosmic ray penetrating particles in the (2.0 - 126) GeV/c range and calculated their charge ratio. For positive particles the momentum spectrum has normal shape in all studied range the same as for negative particles but only for momentum range (2.0 - 32) GeV/c and charge ratio for this range is normal and the same as for cosmic muons. But for momentum P>32GeV/c it was observed negative particles excess flux (~10-5 cm-2 s-1 sr-1 ) with changed charge ratio - R = 0.62 +/0.18 (˜>3.5σ) for momentum range (32GeV/c3σ) and for momentum range (3.6GeV/c107 cm2 ṡsṡsr); 2) the installation place must be on the Earth surface or small underground (< 100 m.w.e.); 3) it is desirable to use track detector for event and particle charge viewing. One of the largest Bubble Chamber "SKAT" (BC), operated from 1976 to 1992 on the Serpukhov Accelerator neutrino beam had satisfied to all these demands. Its operation on the neutrino beam could provide a small background from Accelerator fo r our researches. Accumulated ~ 4 x 2,000,000 stills inside ~ 4 x 1660 rolls during this long period were conserved until now and were ready to analysis. The large Bubble Chamber (450 x 160 x 90 cm3 ) had been placed in greatest magnetic field (17 kG) horizontally directed so as coaxial to it view of 4 stereo photo chambers. So near vertical penetrating cosmic rays could be registered the same as near horizontal neutrino beam events. Full "SKAT" exposition is S-T ~ 4ṡ109 cm2 ṡsṡsr , that is rather more demanded one. It provides us for charge and momentum (MDM > 150 GeV/c) measurements. BC had been placed on the Earth surface, but had large magnetic iron screen (d ~ 2500 g/cm2 = 25m.w.e., Fig.1).

Improving emission uniformity and linearizing band dispersion in nanowire arrays using quasi-aperiodicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, P. Duke; Koleske, Daniel D.; Povinelli, Michelle L.

For this study, we experimentally investigate a new class of quasi-aperiodic structures for improving the emission pattern in nanowire arrays. Efficient normal emission, as well as lasing, can be obtained from III-nitride photonic crystal (PhC) nanowire arrays that utilize slow group velocity modes near the Γ-point in reciprocal space. However, due to symmetry considerations, the emitted far-field pattern of such modes are often ‘donut’-like. Many applications, including lighting for displays or lasers, require a more uniform beam profile in the far-field. Previous work has improved far-field beam uniformity of uncoupled modes by changing the shape of the emitting structure. However,more » in nanowire systems, the shape of nanowires cannot always be arbitrarily changed due to growth or etch considerations. Here, we investigate breaking symmetry by instead changing the position of emitters. Using a quasi-aperiodic geometry, which changes the emitter position within a photonic crystal supercell (2x2), we are able to linearize the photonic bandstructure near the Γ-point and greatly improve emitted far-field uniformity. We realize the III-nitride nanowires structures using a top-down fabrication procedure that produces nanowires with smooth, vertical sidewalls. Comparison of room-temperature micro-photoluminescence (µ-PL) measurements between periodic and quasi-aperiodic nanowire arrays reveal resonances in each structure, with the simple periodic structure producing a donut beam in the emitted far-field and the quasi-aperiodic structure producing a uniform Gaussian-like beam. We investigate the input pump power vs. output intensity in both systems and observe the simple periodic array exhibiting a non-linear relationship, indicative of lasing. We believe that the quasi-aperiodic approach studied here provides an alternate and promising strategy for shaping the emission pattern of nanoemitter systems.« less

Radar systems for the water resources mission. Volume 4: Appendices E-I

NASA Technical Reports Server (NTRS)

Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Hanson, B. C.; Komen, M. J.; Mcmillan, S. B.; Parashar, S. K.

1976-01-01

The use of a scanning antenna beam for a synthetic aperture system was examined. When the resolution required was modest, the radar did not use all the time the beam was passing a given point on the ground to build a synthetic aperture, so time was available to scan the beam to other positions and build several images at different ranges. The scanning synthetic-aperture radar (SCANSAR) could achieve swathwidths of well over 100 km with modest antenna size. Design considerations for a SCANSAR for hydrologic parameter observation are presented. Because of the high sensitivity to soil moisture at angles of incidence near vertical, a 7 to 22 deg swath was considered for that application. For snow and ice monitoring, a 22 to 37 deg scan was used. Frequencies from X-band to L-band were used in the design studies, but the proposed system operated in C-band at 4.75 GHz. It achieved an azimuth resolution of about 50 meters at all angles, with a range resolution varying from 150 meters at 7 deg to 31 meters at 37 deg. The antenna required an aperture of 3 x 4.16 meters, and the average transmitter power was under 2 watts.

Effect of high power CO2 and Yb:YAG laser radiation on the characteristics of TIG arc in atmospherical pressure argon and helium

NASA Astrophysics Data System (ADS)

Wu, Shikai; Xiao, Rongshi

2015-04-01

The effects of laser radiation on the characteristics of the DC tungsten inert gas (TIG) arc were investigated by applying a high power slab CO2 laser and a Yb:YAG disc laser. Experiment results reveal that the arc voltage-current curve shifts downwards, the arc column expands, and the arc temperature rises while the high power CO2 laser beam vertically interacts with the TIG arc in argon. With the increase of the laser power, the voltage-current curve of the arc shifts downwards more significantly, and the closer the laser beam impingement on the arc to the cathode, the more the decrease in arc voltage. Moreover, the arc column expansion and the arc temperature rise occur mainly in the region between the laser beam incident position and the anode. However, the arc characteristics hardly change in the cases of the CO2 laser-helium arc and YAG laser-arc interactions. The reason is that the inverse Bremsstrahlung absorption coefficients are greatly different due to the different electron densities of the argon and helium arcs and the different wave lengths of CO2 and YAG lasers.

Vertical dynamics of a single-span beam subjected to moving mass-suspended payload system with variable speeds

NASA Astrophysics Data System (ADS)

He, Wei

2018-03-01

This paper presents the vertical dynamics of a simply supported Euler-Bernoulli beam subjected to a moving mass-suspended payload system of variable velocities. A planar theoretical model of the moving mass-suspended payload system of variable speeds is developed based on several assumptions: the rope is massless and rigid, and its length keeps constant; the stiffness of the gantry beam is much greater than the supporting beam, and the gantry beam can be treated as a mass particle traveling along the supporting beam; the supporting beam is assumed as a simply supported Bernoulli-Euler beam. The model can be degenerated to consider two classical cases-the moving mass case and the moving payload case. The proposed model is verified using both numerical and experimental methods. To further investigate the effect of possible influential factors, numerical examples are conducted covering a range of parameters, such as variable speeds (acceleration or deceleration), mass ratios of the payload to the total moving load, and the pendulum lengths. The effect of beam flexibility on swing response of the payload is also investigated. It is shown that the effect of a variable speed is significant for the deflections of the beam. The accelerating movement tends to induce larger beam deflections, while the decelerating movement smaller ones. For accelerating or decelerating movements, the moving mass model may underestimate the deflections of the beam compared with the presented model; while for uniform motion, both the moving mass model and the moving mass-payload model lead to same beam responses. Furthermore, it is observed that the swing response of the payload is not sensitive to the stiffness of the beam for operational cases of a moving crane, thus a simple moving payload model can be employed in the swing control of the payload.

Near-surface energy transfers from internal tide beams to smaller vertical scale motions

NASA Astrophysics Data System (ADS)

Chou, S.; Staquet, C.; Carter, G. S.; Luther, D. S.

2016-02-01

Mechanical energy capable of causing diapycnal mixing in the ocean is transferred to the internal wave field when barotropic tides pass over underwater topography and generate internal tides. The resulting internal tide energy is confined in vertically limited structures, or beams. As internal tide beams (ITBs) propagate through regions of non-uniform stratification in the upper ocean, wave energy can be scattered through multiple reflections and refractions, be vertically trapped, or transferred to non-tidal frequencies through different nonlinear processes. Various observations have shown that ITBs are no longer detectable in horizontal kinetic energy beyond the first surface reflection. Importantly, this implies that some of the internal tide energy no longer propagates in to the abyssal ocean and consequently will not be available to maintain the density stratification. Using the NHM, a nonlinear and nonhydrostatic model based on the MITgcm, simulations of an ITB propagating up to the sea surface are examined in order to quantify the transformation of ITB energy to other motions. We compare and contrast the transformations enabled by idealized, smoothly-varying stratification with transformations enabled by realistic stratification containing a broad-band vertical wavenumber spectrum of variations. Preliminary two-dimensional results show that scattering due to small-scale structure in realistic stratification profiles from Hawaii can lead to energy being vertically trapped near the surface. Idealized simulations of "locally" generated internal solitary waves are analyzed in terms of energy flux transfers from the ITB to solitary waves, higher harmonics, and mean flow. The amount of internal tide energy which propagates back down after near-surface reflection of the ITB in different environments is quantified.

High Efficient THz Emission From Unbiased and Biased Semiconductor Nanowires Fabricated Using Electron Beam Lithography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balci, Soner; Czaplewski, David A.; Jung, Il Woong

Besides having perfect control on structural features, such as vertical alignment and uniform distribution by fabricating the wires via e-beam lithography and etching process, we also investigated the THz emission from these fabricated nanowires when they are applied DC bias voltage. To be able to apply a voltage bias, an interdigitated gold (Au) electrode was patterned on the high-quality InGaAs epilayer grown on InP substrate bymolecular beam epitaxy. Afterwards, perfect vertically aligned and uniformly distributed nanowires were fabricated in between the electrodes of this interdigitated pattern so that we could apply voltage bias to improve the THz emission. As amore » result, we achieved enhancement in the emitted THz radiation by ~four times, about 12 dB increase in power ratio at 0.25 THz with a DC biased electric field compared with unbiased NWs.« less

Energy harvesting by dynamic unstability and internal resonance for piezoelectric beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lan, Chunbo; Qin, Weiyang, E-mail: 353481781@qq.com; Deng, Wangzheng

We investigated the energy harvesting of a vertical beam with tip mass under vertical excitations. We applied dynamic unstability and internal resonance to improve the efficiency of harvesting. The experiments of harmonic excitation were carried out. Results show that for the beam there exist internal resonances in the dynamically unstable and the buckling bistable cases. The dynamic unstability is a determinant for strong internal resonance or mode coupling, which can be used to create a large output from piezoelectric patches. Then, the experiments of stochastic excitation were carried out. Results prove that the internal resonance or mode coupling can transfermore » the excitation energy to the low order modes, mainly the first and the second one. This can bring about a large output voltage. For a stochastic excitation, it is proved that there is an optimal weight of tip mass for realizing internal resonance and producing large outputs.« less

Optical levitation measurements with intensity-modulated light beams.

PubMed

Cai, W; Li, F; Sun, S; Wang, Y

1997-10-20

Illumination of an optically levitated particle with an intensity-modulated transverse beam induces a transverse vibration of a particle in an optical trap. Based on this, the trapping force of a trap can be measured. Using an intensity-modulated longitudinal levitating beam causes a particle to move vertically, allowing for the determination of some aerodynamic parameters of a particle in air. The principles and the experimental phenomena are described and the initial results are given.

Horizontal atmospheric turbulence, beam propagation, and modeling

NASA Astrophysics Data System (ADS)

Wilcox, Christopher C.; Santiago, Freddie; Martinez, Ty; Judd, K. Peter; Restaino, Sergio R.

2017-05-01

The turbulent effect from the Earth's atmosphere degrades the performance of an optical imaging system. Many studies have been conducted in the study of beam propagation in a turbulent medium. Horizontal beam propagation and correction presents many challenges when compared to vertical due to the far harsher turbulent conditions and increased complexity it induces. We investigate the collection of beam propagation data, analysis, and use for building a mathematical model of the horizontal turbulent path and the plans for an adaptive optical system to use this information to correct for horizontal path atmospheric turbulence.

Nano-stepper-driven optical shutter for applications in free-space micro-optics

NASA Astrophysics Data System (ADS)

Zawadzka, Justyna; Li, Lijie; Unamuno, Anartz; Uttamchandani, Deepak G.

2002-09-01

In this paper we report a simple design of a micro-optical shutter/attenuator. The standard MUMPS process was used to fabricate the device. A vertically erected, gold-coated, 200x300 mm side length micro-mirror was precisely placed between the end faces of two closely spaced optical fibers. The position of the micro-mirror with respect to the optical fiber end face was controlled by a nano-stepping motor array. Optical and mechanical tests were performed on the device. A 1.55 mm laser beam was sent along the optical fiber. When the micro-mirror was removed from the front of the fiber, the coupling efficiency between two fibers was -10 dBm. Once the micro-mirror was placed in the optical path the coupling efficiency dropped to -51.5 dBm. The best attenuation was obtained when the micro-mirror blocked the whole cross-section of the laser beam diameter. It is evident that the device can operate as a high precision fiber optic attenuator or shutter.

Discussion on the installation checking method of precast composite floor slab with lattice girders

NASA Astrophysics Data System (ADS)

Chen, Li; Jin, Xing; Wang, Yahui; Zhou, Hele; Gu, Jianing

2018-03-01

Based on the installation checking requirements of China’s current standards and the international norms for prefabricated structural precast components, it proposed an installation checking method for precast composite floor slab with lattice girders. By taking an equivalent composite beam consisted of a single lattice girder and the precast concrete slab as the checking object, compression instability stress of upper chords and yield stress of slab distribution reinforcement at the maximum positive moment, tensile yield stress of upper chords, slab normal section normal compression stress and shear instability stress of diagonal bars at the maximum negative moment were checked. And the bending stress and deflection of support beams, strength and compression stability bearing capacity of the vertical support, shear bearing capacity of the bolt and compression bearing capacity of steel tube wall at the bolt were checked at the same time. Every different checking object was given a specific load value and load combination. Application of installation checking method was given and testified by example.

Effects of energy chirp on bunch length measurement in linear accelerator beams

NASA Astrophysics Data System (ADS)

Sabato, L.; Arpaia, P.; Giribono, A.; Liccardo, A.; Mostacci, A.; Palumbo, L.; Vaccarezza, C.; Variola, A.

2017-08-01

The effects of assumptions about bunch properties on the accuracy of the measurement method of the bunch length based on radio frequency deflectors (RFDs) in electron linear accelerators (LINACs) are investigated. In particular, when the electron bunch at the RFD has a non-negligible energy chirp (i.e. a correlation between the longitudinal positions and energies of the particle), the measurement is affected by a deterministic intrinsic error, which is directly related to the RFD phase offset. A case study on this effect in the electron LINAC of a gamma beam source at the Extreme Light Infrastructure-Nuclear Physics (ELI-NP) is reported. The relative error is estimated by using an electron generation and tracking (ELEGANT) code to define the reference measurements of the bunch length. The relative error is proved to increase linearly with the RFD phase offset. In particular, for an offset of {{7}\\circ} , corresponding to a vertical centroid offset at a screen of about 1 mm, the relative error is 4.5%.

Influence of maxillary posterior discrepancy on upper molar vertical position and facial vertical dimensions in subjects with or without skeletal open bite

PubMed Central

Aliaga-Del Castillo, Aron; Pérez-Vargas, Luis Fernando; Flores-Mir, Carlos

2016-01-01

Summary Objectives: To determine the influence of maxillary posterior discrepancy on upper molar vertical position and dentofacial vertical dimensions in individuals with or without skeletal open bite (SOB). Materials and methods: Pre-treatment lateral cephalograms of 139 young adults were examined. The sample was divided into eight groups categorized according to their sagittal and vertical skeletal facial growth pattern and maxillary posterior discrepancy (present or absent). Upper molar vertical position, overbite, lower anterior facial height and facial height ratio were measured. Independent t-test was performed to determine differences between the groups considering maxillary posterior discrepancy. Principal component analysis and MANCOVA test were also used. Results: No statistically significant differences were found comparing the molar vertical position according to maxillary posterior discrepancy for the SOB Class I group or the group with adequate overbite. Significant differences were found in SOB Class II and Class III groups. In addition, an increased molar vertical position was found in the group without posterior discrepancy. Limitations: Some variables closely related with the individual’s intrinsic craniofacial development that could influence the evaluated vertical measurements were not considered. Conclusions and implications: Overall maxillary posterior discrepancy does not appear to have a clear impact on upper molar vertical position or facial vertical dimensions. Only the SOB Class III group without posterior discrepancy had a significant increased upper molar vertical position. PMID:26385786

Influence of maxillary posterior discrepancy on upper molar vertical position and facial vertical dimensions in subjects with or without skeletal open bite.

PubMed

Arriola-Guillén, Luis Ernesto; Aliaga-Del Castillo, Aron; Pérez-Vargas, Luis Fernando; Flores-Mir, Carlos

2016-06-01

To determine the influence of maxillary posterior discrepancy on upper molar vertical position and dentofacial vertical dimensions in individuals with or without skeletal open bite (SOB). Pre-treatment lateral cephalograms of 139 young adults were examined. The sample was divided into eight groups categorized according to their sagittal and vertical skeletal facial growth pattern and maxillary posterior discrepancy (present or absent). Upper molar vertical position, overbite, lower anterior facial height and facial height ratio were measured. Independent t-test was performed to determine differences between the groups considering maxillary posterior discrepancy. Principal component analysis and MANCOVA test were also used. No statistically significant differences were found comparing the molar vertical position according to maxillary posterior discrepancy for the SOB Class I group or the group with adequate overbite. Significant differences were found in SOB Class II and Class III groups. In addition, an increased molar vertical position was found in the group without posterior discrepancy. Some variables closely related with the individual's intrinsic craniofacial development that could influence the evaluated vertical measurements were not considered. Overall maxillary posterior discrepancy does not appear to have a clear impact on upper molar vertical position or facial vertical dimensions. Only the SOB Class III group without posterior discrepancy had a significant increased upper molar vertical position. © The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Airborne Polarized Lidar Detection of Scattering Layers in the Ocean

NASA Astrophysics Data System (ADS)

Vasilkov, Alexander P.; Goldin, Yury A.; Gureev, Boris A.; Hoge, Frank E.; Swift, Robert N.; Wright, C. Wayne

2001-08-01

A polarized lidar technique based on measurements of waveforms of the two orthogonal-polarized components of the backscattered light pulse is proposed to retrieve vertical profiles of the seawater scattering coefficient. The physical rationale for the polarized technique is that depolarization of backscattered light originating from a linearly polarized laser beam is caused largely by multiple small-angle scattering from particulate matter in seawater. The magnitude of the small-angle scattering is determined by the scattering coefficient. Therefore information on the vertical distribution of the scattering coefficient can be derived potentially from measurements of the timedepth dependence of depolarization in the backscattered laser pulse. The polarized technique was verified by field measurements conducted in the Middle Atlantic Bight of the western North Atlantic Ocean that were supported by in situ measurements of the beam attenuation coefficient. The airborne polarized lidar measured the timedepth dependence of the backscattered laser pulse in two orthogonal-polarized components. Vertical profiles of the scattering coefficient retrieved from the timedepth depolarization of the backscattered laser pulse were compared with measured profiles of the beam attenuation coefficient. The comparison showed that retrieved profiles of the scattering coefficient clearly reproduce the main features of the measured profiles of the beam attenuation coefficient. Underwater scattering layers were detected at depths of 2025 m in turbid coastal waters. The improvement in dynamic range afforded by the polarized lidar technique offers a strong potential benefit for airborne lidar bathymetric applications.

Combining split-beam and dual-frequency identification sonars to estimate abundance of anadromous fishes in the Roanoke River, North Carolina

USGS Publications Warehouse

Hughes, Jacob B.; Hightower, Joseph E.

2015-01-01

Riverine hydroacoustic techniques are an effective method for evaluating abundance of upstream migrating anadromous fishes. To use these methods in the Roanoke River, North Carolina, at a wide site with uneven bottom topography, we used a combination of split-beam sonar and dual-frequency identification sonar (DIDSON) deployments. We aimed a split-beam sonar horizontally to monitor midchannel and near-bottom zones continuously over the 3-month spring monitoring periods in 2010 and 2011. The DIDSON was rotated between seven cross-channel locations (using a vertical aim) and nearshore regions (using horizontal aims). Vertical deployment addressed blind spots in split-beam coverage along the bottom and provided reliable information about the cross-channel and vertical distributions of upstream migrants. Using a Bayesian framework, we modeled sonar counts within four cross-channel strata and apportioned counts by species using species proportions from boat electrofishing and gill netting. Modeled estimates (95% credible intervals [CIs]) of total upstream migrants in 2010 and 2011 were 2.5 million (95% CI, 2.4–2.6 million) and 3.6 million (95% CI, 3.4–3.9 million), respectively. Results indicated that upstream migrants are extremely shore- and bottom-oriented, suggesting nearshore DIDSON monitoring improved the accuracy and precision of our estimates. This monitoring protocol and model may be widely applicable to river systems regardless of their cross-sectional width or profile.

Vertically Free-Standing Ordered Pb(Zr0.52Ti0.48)O3 Nanocup Arrays by Template-Assisted Ion Beam Etching

NASA Astrophysics Data System (ADS)

Zhang, Xiaoyan; Tang, Dan; Huang, Kangrong; Hu, Die; Zhang, Fengyuan; Gao, Xingsen; Lu, Xubing; Zhou, Guofu; Zhang, Zhang; Liu, Junming

2016-04-01

In this report, vertically free-standing lead zirconate titanate Pb(Zr0.52Ti0.48)O3 (PZT) nanocup arrays with good ordering and high density (1.3 × 1010 cm-2) were demonstrated. By a template-assisted ion beam etching (IBE) strategy, the PZT formed in the pore-through anodic aluminum oxide (AAO) membrane on the Pt/Si substrate was with a cup-like nanostructure. The mean diameter and height of the PZT nanocups (NCs) was about 80 and 100 nm, respectively, and the wall thickness of NCs was about 20 nm with a hole depth of about 80 nm. Uppermost, the nanocup structure with low aspect ratio realized vertically free-standing arrays when losing the mechanical support from templates, avoiding the collapse or bundling when compared to the typical nanotube arrays. X-ray diffraction (XRD) and Raman spectrum revealed that the as-prepared PZT NCs were in a perovskite phase. By the vertical piezoresponse force microscopy (VPFM) measurements, the vertically free-standing ordered ferroelectric PZT NCs showed well-defined ring-like piezoresponse phase and hysteresis loops, which indicated that the high-density PZT nanocup arrays could have potential applications in ultra-high non-volatile ferroelectric memories (NV-FRAM) or other nanoelectronic devices.

Optical Characterization of IV-VI Mid-Infrared VCSEL

DTIC Science & Technology

2002-01-01

vertical cavity surface emitting laser ( VCSEL ). A power...il quantum well (QW) devices [5], there has little progress until recently in developing mid-IR vertical cavity surface emitting laser ( VCSEL ). This...structures and PbSrSe thin films were grown on Bat; (111) substrates by molecular beam epitaxy ( MBE ) and characterized by Fourier transform infi-ared

Kappa angles in different positions in patients with myopia during LASIK

PubMed Central

Qi, Hui; Jiang, Jing-Jing; Jiang, Yan-Ming; Wang, Li-Qiang; Huang, Yi-Fei

2016-01-01

AIM To investigate the difference in kappa angle between sitting and supine positions during laser-assisted in situ keratomileusis (LASIK). METHODS A retrospective study was performed on 395 eyes from 215 patients with myopia that received LASIK. Low, moderate, and high myopia groups were assigned according to diopters. The horizontal and vertical components of kappa angle in sitting position were measured before the operation, and in supine position during the operation. The data from the two positions were compared and the relationship between kappa angle and diopters were analyzed. RESULTS Two hundred and twenty-three eyes (56.5%) in sitting position and 343 eyes (86.8%) in supine position had positive kappa angles. There were no significant differences in horizontal and vertical components of kappa angle in the sitting position or horizontal components of kappa angle in the supine position between the three groups (P>0.05). A significant difference in the vertical components of kappa angle in the supine position was seen in the three groups (P<0.01). Differences in both horizontal and vertical components of kappa angles were significant between the sitting and supine positions. Positive correlations in both horizontal and vertical components of kappa angles (P<0.05) were found and vertical components of kappa angle in sitting and supine positions were negatively correlated with the degree of myopia (sitting position: r=-0.109; supine position: r=-0.172; P<0.05). CONCLUSION There is a correlation in horizontal and vertical components of kappa angle in sitting and supine positions. Positive correlations in both horizontal and vertical components of kappa angle in sitting and supine positions till the end of the results. This result still needs further observation. Clinicians should take into account different postures when excimer laser surgery needs to be performed. PMID:27162734

First results on the measurements of the proton beam polarization at internal target at Nuclotron1

NASA Astrophysics Data System (ADS)

Ladygin, V. P.; Gurchin, Yu V.; Isupov, A. Yu; Janek, M.; Khrenov, A. N.; Kurilkin, P. K.; Livanov, A. N.; Piyadin, S. M.; Reznikov, S. G.; Skhomenko, Ya T.; Terekhin, A. A.; Tishevsky, A. V.; Averyanov, A. V.; Bazylev, S. N.; Belov, A. S.; Butenko, A. V.; Chernykh, E. V.; Filatov, Yu N.; Fimushkin, V. V.; Krivenkov, D. O.; Kondratenko, A. M.; Kondratenko, M. A.; Kovalenko, A. D.; Slepnev, I. V.; Slepnev, V. M.; Shutov, A. V.; Sidorin, A. O.; Vnukov, I. E.; Volkov, V. S.

2017-12-01

The spin program at NICA using SPD and MPD requires high intensity polarized proton beam with high value of the beam polarization. First results on the measurements of the proton beam polarization performed at internal target at Nuclotron are reported. The polarization of the proton beam provided by new source of polarized ions has been measured at 500 MeV using quasielastic proton-proton scattering and DSS setup at internal target. The obtained value of the vertical polarization of ∼35% is consistent with the calculations taking into account the current magnetic optics of the Nuclotron injection line.

Characterisation of the muon beams for the Muon Ionisation Cooling Experiment

DOE PAGES

Adams, D.; Adey, D.; Alekou, A.; ...

2013-10-01

A novel single-particle technique to measure emittance has been developed and used to characterise seventeen different muon beams for the Muon Ionisation Cooling Experiment (MICE). The muon beams, whose mean momenta vary from 171 to 281 MeV/c, have emittances of approximately 1.2-2.3 π mm-rad horizontally and 0.6-1.0 π mm-rad vertically, a horizontal dispersion of 90-190 mm and momentum spreads of about 25 MeV/c. There is reasonable agreement between the measured parameters of the beams and the results of simulations. The beams are found to meet the requirements of MICE.

Compositional homogeneity and X-ray topographic analyses of CdTe xSe 1-x grown by the vertical Bridgman technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roy, U. N.; Bolotnikov, A. E.; Camarda, G. S.

2015-02-01

We grew CdTe xSe 1-x crystals with nominal Se concentrations of 5%, 7%, and 10% by the vertical Bridgman technique, and evaluated their compositional homogeneity and structural quality at the NSLS’ X-ray fluorescence and white beam X-ray topography beam lines. Both X-ray fluorescence and photoluminescence mapping revealed very high compositional homogeneity of the CdTe xSe 1-x crystals. Here, we noted that those crystals with higher concentrations of Se were more prone to twinning than those with a lower content. The crystals were fairly free from strains and contained low concentrations of sub-grain boundaries and their networks.

Ultra-High Aggregate Bandwidth Two-Dimensional Multiple-Wavelength Diode Laser Arrays

DTIC Science & Technology

1994-04-09

surface temperature across the wafer during the growth of the cavity spacer region using the fact that the molecular beam epitaxy (MBE) growth of GaAs...substrate surface temperature across the wafer during the growth of the cavity spacer region. Using the fact that, during an molecular beam epitaxy (MBE...K. Bacher and J.S. Harris, "Periodically Induced Mode Shift in Vertical Cavity Fabry Perot Etalons Grown by Molecular Beam Epitaxy ," to be presented

Effect of Metal Artifacts on Detection of Vertical Root Fractures Using Two Cone Beam Computed Tomography Systems.

PubMed

Safi, Yaser; Aghdasi, Mohammad Mehdi; Ezoddini-Ardakani, Fatemeh; Beiraghi, Samira; Vasegh, Zahra

2015-01-01

Vertical root fracture (VRF) is common in endodontically treated teeth. Conventional and digital radiographies have limitations for detection of VRFs. Cone-beam computed tomography (CBCT) offers greater detection accuracy of VRFs in comparison with conventional radiography. This study compared the effects of metal artifacts on detection of VRFs by using two CBCT systems. Eighty extracted premolars were selected and sectioned at the level of the cemento enamel junction (CEJ). After preparation, root canals were filled with gutta-percha. Subsequently, two thirds of the root fillings were removed for post space preparation and a custom-made post was cemented into each canal. The teeth were randomly divided into two groups (n=40). In the test group, root fracture was created with Instron universal testing machine. The control teeth remained intact. CBCT scans of all teeth were obtained with either New Tom VGI or Soredex Scanora 3D. Three observers analyzed the images for detection of VRF. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for VRF detection and percentage of probable cases were calculated for each imaging system and compared using non-parametric tests considering the non-normal distribution of data. The inter-observer reproducibility was calculated using the weighted kappa coefficient. There were no statistically significant differences in sensitivity, specificity, PPV and NPV between the two CBCT systems. The effect of metal artifacts on VRF detection was not significantly different between the two CBCT systems.

Intra-Beam Scattering, Impedance, and Instabilities in Ultimate Storage Rings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bane, Karl; /SLAC

We have investigated collective effects in an ultimate storage ring, i.e. one with diffraction limited emittances in both planes, using PEP-X as an example. In an ultimate ring intra-beam scattering (IBS) sets the limit of current that can be stored. In PEP-X, a 4.5 GeV ring running round beams at 200 mA in 3300 bunches, IBS doubles the emittances to 11.5 pm at the design current. The Touschek lifetime is 11 hours. Impedance driven collective effects tend not to be important since the beam current is relatively low. We have investigated collective effects in PEP-X, an ultimate storage ring, i.e.more » one with diffraction limited emittances (at one angstrom wavelength) in both planes. In an ultimate ring intra-beam scattering (IBS) sets the limit of current that can be stored. In PEP-X, IBS doubles the emittances to 11.5 pm at the design current of 200 mA, assuming round beams. The Touschek lifetime is quite large in PEP-X, 11.6 hours, and - near the operating point - increases with decreasing emittance. It is, however, a very sensitive function of momentum acceptance. In an ultimate ring like PEP-X impedance driven collective effects tend not to be important since the beam current is relatively low. Before ultimate PEP-X can be realized, the question of how to run a machine with round beams needs serious study. For example, in this report we assumed that the vertical emittance is coupling dominated. It may turn out that using vertical dispersion is a preferable way to generate round beams. The choice will affect IBS and the Touschek effect.« less

SU-F-T-83: Infant Total Skin Electron Therapy Using Five Fields Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saleh, H; Howlin, T; Massey, V

Purpose: We were presented with a 9 month old boy with Relapsed Acute Myeloid Leukemia (AML) involving the skin. The plan was to treat the entire skin using 6 MeV electrons with the infant under complete anesthesia. The purpose of this work is to commission the 6 MeV electron beam and to develop a technique that can be used to deliver total skin dose to infants with minimal patient immobilization. Methods: A baby mannequin phantom that mimics the child’s length was used to determine the best technique to treat the infant. The 76 cm long phantom was placed on themore » floor. The phantom was placed in four unique immobilization devices to simulate four different treatment positions (anterior, posterior, left lateral and right lateral). Radiochromic films were used to determine beam profile in both axial and radial directions, and percent depth dose (PDD). Absolute calibration of the machine output at 214 cm distance was measured using an Exradin A11 parallel-plate ion chamber. A 1.0 cm plexiglass scatter plate was inserted in the collimator. Mosfet dosimeters were used for dose verification for phantom and and patient. Results: At 214 cm source to surface distance (SSD) using gantry angle of + 20o from vertical beam flatness is + 10% in the radial direction over a region of 70 cm and + 4% in the axial direction over 60 cm. A five field arrangement was determined to optimally deliver the desired dose with > 90% uniformity. The fifth field was used to boost the head vertex. Conclusion: It is possible to treat sedated infants with total skin dose using five positions. Four positions were enough to cover the body and the fifth position boosts the vertex of the head. All fractions can be reproduced accurately daily because of the patient’s stable immobilization.« less

Beam position monitor

DOEpatents

Alkire, Randy W.; Rosenbaum, Gerold; Evans, Gwyndaf

2003-07-22

An apparatus for determining the position of an x-ray beam relative to a desired beam axis. Where the apparatus is positioned along the beam path so that a thin metal foil target intersects the x-ray beam generating fluorescent radiation. A PIN diode array is positioned so that a portion of the fluorescent radiation is intercepted by the array resulting in an a series of electrical signals from the PIN diodes making up the array. The signals are then analyzed and the position of the x-ray beam is determined relative to the desired beam path.

Linear Collider Test Facility: Twiss Parameter Analysis at the IP/Post-IP Location of the ATF2 Beam Line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolzon, Benoit; /Annecy, LAPP; Jeremie, Andrea

2012-07-02

At the first stage of the ATF2 beam tuning, vertical beam size is usually bigger than 3 {micro}m at the IP. Beam waist measurements using wire scanners and a laser wire are usually performed to check the initial matching of the beam through to the IP. These measurements are described in this paper for the optics currently used ({beta}{sub x} = 4cm and {beta}{sub y} = 1mm). Software implemented in the control room to automate these measurements with integrated analysis is also described. Measurements showed that {beta} functions and emittances were within errors of measurements when no rematching and couplingmore » corrections were done. However, it was observed that the waist in the horizontal (X) and vertical (Y) plane was abnormally shifted and simulations were performed to try to understand these shifts. They also showed that multiknobs are needed in the current optics to correct simultaneously {alpha}{sub x}, {alpha}{sub y} and the horizontal dispersion (D{sub x}). Such multiknobs were found and their linearity and orthogonality were successfully checked using MAD optics code. The software for these multiknobs was implemented in the control room and waist scan measurements using the {alpha}{sub y} knob were successfully performed.« less

Ultrafast Directional Beam Switching in Coupled VCSELs

NASA Technical Reports Server (NTRS)

Ning, Cun-Zheng; Goorjian, Peter

2001-01-01

We propose a new approach to performing ultrafast directional beam switching using two coupled Vertical-Cavity Surface-Emitting Lasers (VCSELs). The proposed strategy is demonstrated for two VCSELs of 5.6 microns in diameter placed about 1 micron apart from the edges, showing a switching speed of 42 GHz with a maximum far-field angle span of about 10 degrees.

Using virtual ridge augmentation and 3D printing to fabricate a titanium mesh positioning device: A novel technique letter.

PubMed

Al-Ardah, Aladdin; Alqahtani, Nasser; AlHelal, Abdulaziz; Goodacre, Brian; Swamidass, Rajesh; Garbacea, Antoanela; Lozada, Jaime

2018-05-02

This technique describes a novel approach for planning and augmenting a large bony defect using a titanium mesh (TiMe). A 3-dimensional (3D) surgical model was virtually created from a cone beam computed tomography (CBCT) and wax-pattern of the final prosthetic outcome. The required bone volume (horizontally and vertically) was digitally augmented and then 3D printed to create a bone model. The 3D model was then used to contour the TiMe in accordance with the digital augmentation. With the contoured / preformed TiMe on the 3D printed model a positioning jig was made to aid the placement of the TiMe as planned during surgery. Although this technique does not impact the final outcome of the augmentation procedure, it allows the clinician to virtually design the augmentation, preform and contour the TiMe, and create a positioning jig reducing surgical time and error.

Interferometric weak measurement of photon polarization

NASA Astrophysics Data System (ADS)

Iinuma, Masataka; Suzuki, Yutaro; Taguchi, Gen; Kadoya, Yutaka; Hofmann, Holger F.

2011-10-01

We realize a minimum back-action quantum non-demolition measurement of variable strength on photon polarization in the diagonal(PM) basis by two-mode path interference. This method uses the phase difference between the positive (P) and negative (M) superpositions in the interference between the horizontal (H) and vertical (V) polarized paths in the input beam. Although the interference can not occur when the H and V polarizations are distinguishable, a well-controlled amount of interference is induced by erasing the H and V information using a coherent rotation of polarization toward a common diagonal polarization. This method is particularly suitable for the realization of weak measurements, where the control of the back-action is essential.

Studies of the Coherent Half-Integer Resonance

NASA Astrophysics Data System (ADS)

Cousineau, Sarah; Holmes, Jeff; Galambos, John; Macek, Robert; Fedotov, Alexei; Wei, Jie

2002-12-01

We present studies of space-charge-induced beam profile broadening at high intensities in the Proton Storage Ring (PSR) at Los Alamos National Laboratory. Previous work has associated the observed broadening in the vertical direction with the coherent half integer resonance [1]. Here, we study the effect of the space charge environment on this resonance; specifically, we investigate the strength of the resonance versus beam intensity, longitudinal bunching factor, transverse lattice tune, and two different beam injection scenarios. For each case, detailed particle-in-cell simulations are combined with experimental results to elucidate the behavior and sensitivity of the beam resonance response.

BEAM DIAGNOSTICS USING BPM SIGNALS FROM INJECTED AND STORED BEAMS IN A STORAGE RING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, G.M.; Shaftan; T.

2011-03-28

Many modern light sources are operating in top-off injection mode or are being upgraded to top-off injection mode. The storage ring always has the stored beam and injected beam for top-off injection mode. So the BPM data is the mixture of both beam positions and the injected beam position cannot be measured directly. We propose to use dedicated wide band BPM electronics in the NSLS II storage ring to retrieve the injected beam trajectory with the singular value decomposition (SVD) method. The beam position monitor (BPM) has the capability to measure bunch-by-bunch beam position. Similar electronics can be used tomore » measure the bunch-by-bunch beam current which is necessary to get the injection beam position. The measurement precision of current needs to be evaluated since button BPM sum signal has position dependence. The injected beam trajectory can be measured and monitored all the time without dumping the stored beam. We can adjust and optimize the injected beam trajectory to maximize the injection efficiency. We can also measure the storage ring acceptance by mapping the injected beam trajectory.« less

Laser system for testing radiation imaging detector circuits

NASA Astrophysics Data System (ADS)

Zubrzycka, Weronika; Kasinski, Krzysztof

2015-09-01

Performance and functionality of radiation imaging detector circuits in charge and position measurement systems need to meet tight requirements. It is therefore necessary to thoroughly test sensors as well as read-out electronics. The major disadvantages of using radioactive sources or particle beams for testing are high financial expenses and limited accessibility. As an alternative short pulses of well-focused laser beam are often used for preliminary tests. There are number of laser-based devices available on the market, but very often their applicability in this field is limited. This paper describes concept, design and validation of laser system for testing silicon sensor based radiation imaging detector circuits. The emphasis is put on keeping overall costs low while achieving all required goals: mobility, flexible parameters, remote control and possibility of carrying out automated tests. The main part of the developed device is an optical pick-up unit (OPU) used in optical disc drives. The hardware includes FPGA-controlled circuits for laser positioning in 2 dimensions (horizontal and vertical), precision timing (frequency and number) and amplitude (diode current) of short ns-scale (3.2 ns) light pulses. The system is controlled via USB interface by a dedicated LabVIEW-based application enabling full manual or semi-automated test procedures.

A measurement of B0 meson properties using partially reconstructed B0 to D*- pi+ and B0 tp D*- lepton+ nu-lepton decays with the BABAR detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barrera, Barbara

The two B{sup 0} decay processes B{sup 0} {yields} D*{sup -} {pi}{sup +} and B{sup 0} {yields} D*{sup -} {ell}{sup +} {nu}{sub {ell}} have been studied by means of a partial reconstruction technique using a data sample collected with the BABAR detector at the PEP-II storage ring. To increase statistics, only the soft {pi}{sup -} from the decay D*{sup -} {yields} {pi}{sup -} D{sup 0} was used in association with either an oppositely-charged high-momentum pion or lepton. Events were then identified by exploiting the constraints from the simple kinematics of {Upsilon}(4S) decays. A clear signature is obtained in each case.more » The position of the B{sup 0} decay point was obtained from the reconstructed {pi}{sup +} ({ell}{sup +}){pi}{sup -} vertex. The position of the other {bar B}{sup 0} in the event was also determined. Taking advantage of the boost given to the {Upsilon}(4S) system by the asymmetric beam energies of PEP-II, the lifetime of the B{sup 0} meson has been measured from the separation distance between the two vertices along the beam direction.« less

Master dye laser oscillator including a specific grating assembly for use therein

DOEpatents

Davin, James M.

1992-01-01

A dye laser oscillator for producing a tuned dye beam is disclosed herein and includes, among other components, a beam output coupling assembly, a dye cell assembly, a beam expander assembly, an etalon assembly, and a grating assembly. Each of three assemblies is vertically supported from a horizontal base so as to be readily removable from the base without interference from or interfering with the other assemblies. The particular grating assembly disclosed is specifically designed for proper optical alignment with the intended path of the dye beam to be produced and for accurate pivotal movement relative to the beam path in order to function as a coarse tuning mechanism in the production of the ultimately tuned beam.

Master dye laser oscillator including a specific grating assembly for use therein

DOEpatents

Davin, J.M.

1992-09-01

A dye laser oscillator for producing a tuned dye beam is disclosed herein and includes, among other components, a beam output coupling assembly, a dye cell assembly, a beam expander assembly, an etalon assembly, and a grating assembly. Each of three assemblies is vertically supported from a horizontal base so as to be readily removable from the base without interference from or interfering with the other assemblies. The particular grating assembly disclosed is specifically designed for proper optical alignment with the intended path of the dye beam to be produced and for accurate pivotal movement relative to the beam path in order to function as a coarse tuning mechanism in the production of the ultimately tuned beam. 5 figs.

Generation of vector beams using a double-wedge depolarizer: Non-quantum entanglement

NASA Astrophysics Data System (ADS)

Samlan, C. T.; Viswanathan, Nirmal K.

2016-07-01

Propagation of horizontally polarized Gaussian beam through a double-wedge depolarizer generates vector beams with spatially varying state of polarization. Jones calculus is used to show that such beams are maximally nonseparable on the basis of even (Gaussian)-odd (Hermite-Gaussian) mode parity and horizontal-vertical polarization state. The maximum nonseparability in the two degrees of freedom of the vector beam at the double wedge depolarizer output is verified experimentally using a modified Sagnac interferometer and linear analyser projected interferograms to measure the concurrence 0.94±0.002 and violation of Clauser-Horne-Shimony-Holt form of Bell-like inequality 2.704±0.024. The investigation is carried out in the context of the use of vector beams for metrological applications.

Method and apparatus for measuring properties of particle beams using thermo-resistive material properties

DOEpatents

Degtiarenko, Pavel V.; Dotson, Danny Wayne

2007-10-09

A beam position detector for measuring the properties of a charged particle beam, including the beam's position, size, shape, and intensity. One or more absorbers are constructed of thermo-resistive material and positioned to intercept and absorb a portion of the incoming beam power, thereby causing local heating of each absorber. The local temperature increase distribution across the absorber, or the distribution between different absorbers, will depend on the intensity, size, and position of the beam. The absorbers are constructed of a material having a strong dependence of electrical resistivity on temperature. The beam position detector has no moving parts in the vicinity of the beam and is especially suited to beam areas having high ionizing radiation dose rates or poor beam quality, including beams dispersed in the transverse direction and in their time radio frequency structure.

SU-F-J-42: Comparison of Varian TrueBeam Cone-Beam CT and BrainLab ExacTrac X-Ray for Cranial Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, J; Shi, W; Andrews, D

2016-06-15

Purpose: To compare online image registrations of TrueBeam cone-beam CT (CBCT) and BrainLab ExacTrac x-ray imaging systems for cranial radiotherapy. Method: Phantom and patient studies were performed on a Varian TrueBeam STx linear accelerator (Version 2.5), which is integrated with a BrainLab ExacTrac imaging system (Version 6.1.1). The phantom study was based on a Rando head phantom, which was designed to evaluate isocenter-location dependence of the image registrations. Ten isocenters were selected at various locations in the phantom, which represented clinical treatment sites. CBCT and ExacTrac x-ray images were taken when the phantom was located at each isocenter. The patientmore » study included thirteen patients. CBCT and ExacTrac x-ray images were taken at each patient’s treatment position. Six-dimensional image registrations were performed on CBCT and ExacTrac, and residual errors calculated from CBCT and ExacTrac were compared. Results: In the phantom study, the average residual-error differences between CBCT and ExacTrac image registrations were: 0.16±0.10 mm, 0.35±0.20 mm, and 0.21±0.15 mm, in the vertical, longitudinal, and lateral directions, respectively. The average residual-error differences in the rotation, roll, and pitch were: 0.36±0.11 degree, 0.14±0.10 degree, and 0.12±0.10 degree, respectively. In the patient study, the average residual-error differences in the vertical, longitudinal, and lateral directions were: 0.13±0.13 mm, 0.37±0.21 mm, 0.22±0.17 mm, respectively. The average residual-error differences in the rotation, roll, and pitch were: 0.30±0.10 degree, 0.18±0.11 degree, and 0.22±0.13 degree, respectively. Larger residual-error differences (up to 0.79 mm) were observed in the longitudinal direction in the phantom and patient studies where isocenters were located in or close to frontal lobes, i.e., located superficially. Conclusion: Overall, the average residual-error differences were within 0.4 mm in the translational directions and were within 0.4 degree in the rotational directions.« less

Coherent combining of a 4 kW, eight-element fiber amplifier array.

PubMed

Yu, C X; Augst, S J; Redmond, S M; Goldizen, K C; Murphy, D V; Sanchez, A; Fan, T Y

2011-07-15

Commercial 0.5 kW Yb-doped fiber amplifiers have been characterized and found to be suitable for coherent beam combining. Eight such fiber amplifiers have been coherently combined in a tiled-aperture configuration with 78% combining efficiency and total output power of 4 kW. The power-in-the-bucket vertical beam quality of the combined output is 1.25 times diffraction limited at full power. The beam-combining performance is independent of output power. © 2011 Optical Society of America

Vertical Root Fracture Detection Using Limited-FOV Cone-Beam Computed Tomography

DTIC Science & Technology

2012-06-01

A thesis submitted to the Faculty of the Endodontics Graduate Program Naval Postgraduate Dental School Uniformed Services...Dental Program Navy Medicine Professional Development Center Terry D. Webb, DDS, MS CAPT, DC, USN Chairman, Endodontics Dept. Glen M. Imamura, S...Computed Tomography Geoffrey McMurray, DDS, MS ABSTRACT Introduction: Vertical root fractures (VRF) often occur in endodontically treated teeth

Effect of train carbody's parameters on vertical bending stiffness performance

NASA Astrophysics Data System (ADS)

Yang, Guangwu; Wang, Changke; Xiang, Futeng; Xiao, Shoune

2016-10-01

Finite element analysis(FEA) and modal test are main methods to give the first-order vertical bending vibration frequency of train carbody at present, but they are inefficiency and waste plenty of time. Based on Timoshenko beam theory, the bending deformation, moment of inertia and shear deformation are considered. Carbody is divided into some parts with the same length, and it's stiffness is calculated with series principle, it's cross section area, moment of inertia and shear shape coefficient is equivalent by segment length, and the fimal corrected first-order vertical bending vibration frequency analytical formula is deduced. There are 6 simple carbodies and 1 real carbody as examples to test the formula, all analysis frequencies are very close to their FEA frequencies, and especially for the real carbody, the error between analysis and experiment frequency is 0.75%. Based on the analytic formula, sensitivity analysis of the real carbody's design parameters is done, and some main parameters are found. The series principle of carbody stiffness is introduced into Timoshenko beam theory to deduce a formula, which can estimate the first-order vertical bending vibration frequency of carbody quickly without traditional FEA method and provide a reference to design engineers.

Double wedge prism based beam deflector for precise laser beam steering

NASA Astrophysics Data System (ADS)

Tyszka, Krzysztof; Dobosz, Marek; Bilaszewski, Tomasz

2018-02-01

Aiming to increase laser beam pointing stability required in interferometric measurements, we designed a laser beam deflector intended for active laser beam stabilization systems. The design is based on two wedge-prisms: the deflecting wedge driven by a tilting piezo-platform and the fixed wedge to compensate initial beam deflection. Our design allows linear beam steering, independently in the horizontal or vertical direction, with resolution of less than 1 μrad in a range of more than 100 μrad, and no initial deflection of the beam. Moreover, the ratio of the output beam deflection angle and the wedge tilt angle is less than 0.1; therefore, the noise influence is significantly reduced in comparison to standard mirror-based deflectors. The theoretical analyses support the designing process and can serve as a guide to wedge-prism selection. The experimental results are in agreement with theory and confirm the advantages of the presented double wedge system.

Experimental study: Underwater propagation of polarized flat top partially coherent laser beams with a varying degree of spatial coherence

NASA Astrophysics Data System (ADS)

Avramov-Zamurovic, S.; Nelson, C.

2018-10-01

We report on experiments where spatially partially coherent laser beams with flat top intensity profiles were propagated underwater. Two scenarios were explored: still water and mechanically moved entrained salt scatterers. Gaussian, fully spatially coherent beams, and Multi-Gaussian Schell model beams with varying degrees of spatial coherence were used in the experiments. The main objective of our study was the exploration of the scintillation performance of scalar beams, with both vertical and horizontal polarizations, and the comparison with electromagnetic beams that have a randomly varying polarization. The results from our investigation show up to a 50% scintillation index reduction for the case with electromagnetic beams. In addition, we observed that the fully coherent beam performance deteriorates significantly relative to the spatially partially coherent beams when the conditions become more complex, changing from still water conditions to the propagation through mechanically moved entrained salt scatterers.

A beam position monitor for the diagnostic line in MEBT2 of J-PARC linac

NASA Astrophysics Data System (ADS)

Miura, A.; Tamura, J.; Kawane, Y.

2017-07-01

In the linac of the Japan Proton Accelerator Research Complex (J-PARC), the neutral hydrogen (H0) beam from the negative hydrogen ion (H-) beam is one of key issues in mitigating beam losses. To diagnose H0 particles, we installed a set of beam-bump magnets to generate a chicane orbit of the H- beam. The beam position monitors (BPMs) in the beam line are used for orbit correction to maintain the beam displacement within 2.0 mm from the duct center. To measure the beam displacement under different drive currents of the beam-bump magnets, a new wide-range BPM was designed and manufactured to evaluate the horizontal beam position by using a correction function to compensate for non-linearity. We also employed the beam profile monitor (WSM: wire scanner monitor) to measure the H- beam profile, which helped us to compare the beam position measurements. In this paper, the design and the performance of the wide-range BPM are described. In addition, we present a comparison of the beam position measured by the BPM and the WSM.

Wind turbine generator with improved operating subassemblies

DOEpatents

Cheney, Jr., Marvin C.

1985-01-01

A wind turbine includes a yaw spring return assembly to return the nacelle from a position to which it has been rotated by yawing forces, thus preventing excessive twisting of the power cables and control cables. It also includes negative coning restrainers to limit the bending of the flexible arms of the rotor towards the tower, and stop means on the rotor shaft to orient the blades in a vertical position during periods when the unit is upwind when the wind commences. A pendulum pitch control mechanism is improved by orienting the pivot axis for the pendulum arm at an angle to the longitudinal axis of its support arm, and excessive creep is of the synthetic resin flexible beam support for the blades is prevented by a restraining cable which limits the extent of pivoting of the pendulum during normal operation but which will permit further pivoting under abnormal conditions to cause the rotor to stall.

Validation of PEP-II Resonantly Excited Turn-by-Turn BPM Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Yiton T.; Cai, Yunhai; Colocho, William.

2007-06-28

For optics measurement and modeling of the PEP-II electron (HER) and position (LER) storage rings, we have been doing well with MIA [1] which requires analyzing turn-by-turn Beam Position Monitor (BPM) data that are resonantly excited at the horizontal, vertical, and longitudinal tunes. However, in anticipation that certain BPM buttons and even pins in the PEP-II IR region would be missing for the run starting in January 2007, we had been developing a data validation process to reduce the effect due to the reduced BPM data accuracy on PEP-II optics measurement and modeling. Besides the routine process for ranking BPMmore » noise level through data correlation among BPMs with a singular-value decomposition (SVD), we could also check BPM data symplecticity by comparing the invariant ratios. Results from PEP-II measurement will be presented.« less

1.9 W continuous-wave single transverse mode emission from 1060 nm edge-emitting lasers with vertically extended lasing area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miah, M. J., E-mail: jarez.miah@tu-berlin.de; Posilovic, K.; Kalosha, V. P.

2014-10-13

High-brightness edge-emitting semiconductor lasers having a vertically extended waveguide structure emitting in the 1060 nm range are investigated. Ridge waveguide (RW) lasers with 9 μm stripe width and 2.64 mm cavity length yield highest to date single transverse mode output power for RW lasers in the 1060 nm range. The lasers provide 1.9 W single transverse mode optical power under continuous-wave (cw) operation with narrow beam divergences of 9° in lateral and 14° (full width at half maximum) in vertical direction. The beam quality factor M{sup 2} is less than 1.9 up to 1.9 W optical power. A maximum brightness of 72 MWcm{sup −2}sr{supmore » −1} is obtained. 100 μm wide and 3 mm long unpassivated broad area lasers provide more than 9 W optical power in cw operation.« less

Cylindrical surface profile and diameter measuring tool and method

NASA Technical Reports Server (NTRS)

Currie, James R. (Inventor); Kissel, Ralph R. (Inventor); Smith, Earnest C. (Inventor); Oliver, Charles E. (Inventor); Redmon, John W., Sr. (Inventor); Wallace, Charles C. (Inventor); Swanson, Charles P. (Inventor)

1987-01-01

A tool is shown having a cross beam assembly made of beams joined by a center box structure. The assembly is adapted to be mounted by brackets to the outer end of a cylindrical case. The center box structure has a vertical shaft rotatably mounted therein and extending beneath the assembly. Secured to the vertical shaft is a radius arm which is adapted to rotate with the shaft. On the longer end of the radius arm is a measuring tip which contacts the cylindrical surface to be measured and which provides an electric signal representing the radius of the cylindrical surface from the center of rotation of the radius arm. An electric servomotor rotates the vertical shaft and an electronic resolver provides an electric signal representing the angle of rotation of the shaft. The electric signals are provided to a computer station which has software for its computer to calculate and print out the continuous circumference profile of the cylindrical surface, and give its true diameter and the deviations from the ideal circle.

Distributed support modelling for vertical track dynamic analysis

NASA Astrophysics Data System (ADS)

Blanco, B.; Alonso, A.; Kari, L.; Gil-Negrete, N.; Giménez, J. G.

2018-04-01

The finite length nature of rail-pad supports is characterised by a Timoshenko beam element formulation over an elastic foundation, giving rise to the distributed support element. The new element is integrated into a vertical track model, which is solved in frequency and time domain. The developed formulation is obtained by solving the governing equations of a Timoshenko beam for this particular case. The interaction between sleeper and rail via the elastic connection is considered in an analytical, compact and efficient way. The modelling technique results in realistic amplitudes of the 'pinned-pinned' vibration mode and, additionally, it leads to a smooth evolution of the contact force temporal response and to reduced amplitudes of the rail vertical oscillation, as compared to the results from concentrated support models. Simulations are performed for both parametric and sinusoidal roughness excitation. The model of support proposed here is compared with a previous finite length model developed by other authors, coming to the conclusion that the proposed model gives accurate results at a reduced computational cost.

Transmission XMCD-PEEM imaging of an engineered vertical FEBID cobalt nanowire with a domain wall

NASA Astrophysics Data System (ADS)

Wartelle, A.; Pablo-Navarro, J.; Staňo, M.; Bochmann, S.; Pairis, S.; Rioult, M.; Thirion, C.; Belkhou, R.; de Teresa, J. M.; Magén, C.; Fruchart, O.

2018-01-01

Using focused electron-beam-induced deposition, we fabricate a vertical, platinum-coated cobalt nanowire with a controlled three-dimensional structure. The latter is engineered to feature bends along the height: these are used as pinning sites for domain walls, which are obtained at remanence after saturation of the nanostructure in a horizontally applied magnetic field. The presence of domain walls is investigated using x-ray magnetic circular dichroism (XMCD) coupled to photoemission electron microscopy (PEEM). The vertical geometry of our sample combined with the low incidence of the x-ray beam produce an extended wire shadow which we use to recover the wire’s magnetic configuration. In this transmission configuration, the whole sample volume is probed, thus circumventing the limitation of PEEM to surfaces. This article reports on the first study of magnetic nanostructures standing perpendicular to the substrate with XMCD-PEEM. The use of this technique in shadow mode enabled us to confirm the presence of a domain wall without direct imaging of the nanowire.

Characterisation of the properties of a negative hydrogen ion beam by several beam diagnostic techniques

NASA Astrophysics Data System (ADS)

Maurizio, R.; Fantz, U.; Bonomo, F.; Serianni, G.

2016-06-01

The beam properties of the BATMAN negative ion source, which is the prototype of one module of the source for the ITER neutral beam injection system, are characterised by means of three diagnostic techniques: beam emission spectroscopy (BES), the experimental calorimeter mini-STRIKE and a copper calorimeter. The main beam parameters—beam divergence, homogeneity and top-bottom asymmetries—are studied in different operational scenarios: with different magnetic filter field setups, source settings and with different gases (hydrogen or deuterium). Among all dependences, the influence of the magnetic field configuration on the beam and the evolution of the beam features during some conditioning days are investigated in detail. Data show that the stronger the filter field in the beam region, the higher the beam top-bottom asymmetry—likely a v× B effect. During the conditioning of the source, such vertical beam asymmetry increases as well, suggesting an inhomogeneous H -production at the first grid of the extraction system.

A versatile system for optical manipulation experiments

NASA Astrophysics Data System (ADS)

Hanstorp, Dag; Ivanov, Maksym; Alemán Hernández, Ademir F.; Enger, Jonas; Gallego, Ana M.; Isaksson, Oscar; Karlsson, Carl-Joar; Monroy Villa, Ricardo; Varghese, Alvin; Chang, Kelken

2017-08-01

In this paper a versatile experimental system for optical levitation is presented. Microscopic liquid droplets are produced on demand from piezo-electrically driven dispensers. The charge of the droplets is controlled by applying an electric field on the piezo-dispenser head. The dispenser releases droplets into a vertically focused laser beam. The size and position in 3 dimensions of trapped droplets are measured using two orthogonally placed high speed cameras. Alternatively, the vertical position is determined by imaging scattered light onto a position sensitive detector. The charge of a trapped droplets is determined by recording its motion when an electric field is applied, and the charge can be altered by exposing the droplet to a radioactive source or UV light. Further, spectroscopic information of the trapped droplet is obtained by imaging the droplet on the entrance slit of a spectrometer. Finally, the trapping cell can be evacuated, allowing investigations of droplet dynamics in vacuum. The system is utilized to study a variety of physical phenomena, and three pilot experiments are given in this paper. First, a system used to control and measure the charge of the droplet is presented. Second, it is demonstrated how particles can be made to rotate and spin by trapping them using optical vortices. Finally, the Raman spectra of trapped glycerol droplets are obtained and analyzed. The long term goal of this work is to create a system where interactions of droplets with the surrounding medium or with other droplets can be studied with full control of all physical variables.

A computer aided treatment event recognition system in radiation therapy.

PubMed

Xia, Junyi; Mart, Christopher; Bayouth, John

2014-01-01

To develop an automated system to safeguard radiation therapy treatments by analyzing electronic treatment records and reporting treatment events. CATERS (Computer Aided Treatment Event Recognition System) was developed to detect treatment events by retrieving and analyzing electronic treatment records. CATERS is designed to make the treatment monitoring process more efficient by automating the search of the electronic record for possible deviations from physician's intention, such as logical inconsistencies as well as aberrant treatment parameters (e.g., beam energy, dose, table position, prescription change, treatment overrides, etc). Over a 5 month period (July 2012-November 2012), physicists were assisted by the CATERS software in conducting normal weekly chart checks with the aims of (a) determining the relative frequency of particular events in the authors' clinic and (b) incorporating these checks into the CATERS. During this study period, 491 patients were treated at the University of Iowa Hospitals and Clinics for a total of 7692 fractions. All treatment records from the 5 month analysis period were evaluated using all the checks incorporated into CATERS after the training period. About 553 events were detected as being exceptions, although none of them had significant dosimetric impact on patient treatments. These events included every known event type that was discovered during the trial period. A frequency analysis of the events showed that the top three types of detected events were couch position override (3.2%), extra cone beam imaging (1.85%), and significant couch position deviation (1.31%). The significant couch deviation is defined as the number of treatments where couch vertical exceeded two times standard deviation of all couch verticals, or couch lateral/longitudinal exceeded three times standard deviation of all couch laterals and longitudinals. On average, the application takes about 1 s per patient when executed on either a desktop computer or a mobile device. CATERS offers an effective tool to detect and report treatment events. Automation and rapid processing enables electronic record interrogation daily, alerting the medical physicist of deviations potentially days prior to performing weekly check. The output of CATERS could also be utilized as an important input to failure mode and effects analysis.

Results from the First Beam-Induced Reconstructed Tracks in the LHCb Vertex Locator

NASA Astrophysics Data System (ADS)

Rodrigues, E.

2010-04-01

LHCb is a dedicated experiment at the LHC to study CP violation and rare b decays. The vertex locator (VELO) is a silicon strip detector designed to measure precisely the production and decay vertices of B-mesons. The detector is positioned at 8 mm of the LHC beams and will operate in an extremely harsh radiation environment. The VELO consists of two retractable detector halves with 21 silicon micro-strip tracking modules each. A module is composed of two n+-on-n 300 μm thick half disc sensors with R and Φ micro-strip geometry. The detectors are operated in vacuum and a bi-phase CO2 cooling system is used. The full system has been operated since June 2008 and its commissioning experience will be reported. During the LHC synchronization tests in August and September 2008, and June 2009 the LHCb detectors measured secondary particles produced by the interaction of the LHC primary beam on a beam dump. About 50,000 tracks were reconstructed in the VELO and they were used to derive the relative timing alignment between the sensors and for the first evaluation of the spatial alignment. Using this track sample the VELO has been aligned to an accuracy of 5 μm. A single hit resolution of 10 μm was obtained at the smallest pitch for tracks of perpendicular incidence. The design and the main components of the detector system are introduced. The commissioning of the detector is reported and the talk will focus on the results obtained using the first beam-induced reconstructed tracks.

Board-to-Board Free-Space Optical Interconnections Passing through Boards for a Bookshelf-Assembled Terabit-Per-Second-Class ATM Switch.

PubMed

Hirabayashi, K; Yamamoto, T; Matsuo, S; Hino, S

1998-05-10

We propose free-space optical interconnections for a bookshelf-assembled terabit-per-second-class ATM switch. Thousands of arrayed optical beams, each having a rate of a few gigabits per second, propagate vertically to printed circuit boards, passing through some boards, and are connected to arbitrary transmitters and receivers on boards by polarization controllers and prism arrays. We describe a preliminary experiment using a 1-mm-pitch 2 x 2 beam-collimator array that uses vertical-cavity surface-emitting laser diodes. These optical interconnections can be made quite stable in terms of mechanical shock and temperature fluctuation by the attachment of reinforcing frames to the boards and use of an autoalignment system.

A 4 Tesla Superconducting Magnet Developed for a 6 Circle Huber Diffractometer at the XMaS Beamline

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, P. B. J.; Brown, S. D.; Bouchenoire, L.

2007-01-19

We report here on the development and testing of a 4 Tesla cryogen free superconducting magnet designed to fit within the Euler cradle of a 6 circle Huber diffractometer, allowing scattering in both the vertical and horizontal planes. The geometry of this magnet allows the field to be applied in three orientations. The first being along the beam direction, the second with the field transverse to the beam direction a horizontal plane and finally the field can be applied vertically with respect to the beam. The magnet has a warm bore and an open geometry of 180 deg. , allowingmore » large access to reciprocal space. A variable temperature insert has been developed, which is capable of working down to a temperature of 1.7 K and operating over a wide range of angles whilst maintaining a temperature stability of a few mK. Initial ferromagnetic diffraction measurements have been carried out on single crystal Tb and Dy samples.« less

Vertically Free-Standing Ordered Pb(Zr0.52Ti0.48)O3 Nanocup Arrays by Template-Assisted Ion Beam Etching.

PubMed

Zhang, Xiaoyan; Tang, Dan; Huang, Kangrong; Hu, Die; Zhang, Fengyuan; Gao, Xingsen; Lu, Xubing; Zhou, Guofu; Zhang, Zhang; Liu, Junming

2016-12-01

In this report, vertically free-standing lead zirconate titanate Pb(Zr0.52Ti0.48)O3 (PZT) nanocup arrays with good ordering and high density (1.3 × 10(10) cm(-2)) were demonstrated. By a template-assisted ion beam etching (IBE) strategy, the PZT formed in the pore-through anodic aluminum oxide (AAO) membrane on the Pt/Si substrate was with a cup-like nanostructure. The mean diameter and height of the PZT nanocups (NCs) was about 80 and 100 nm, respectively, and the wall thickness of NCs was about 20 nm with a hole depth of about 80 nm. Uppermost, the nanocup structure with low aspect ratio realized vertically free-standing arrays when losing the mechanical support from templates, avoiding the collapse or bundling when compared to the typical nanotube arrays. X-ray diffraction (XRD) and Raman spectrum revealed that the as-prepared PZT NCs were in a perovskite phase. By the vertical piezoresponse force microscopy (VPFM) measurements, the vertically free-standing ordered ferroelectric PZT NCs showed well-defined ring-like piezoresponse phase and hysteresis loops, which indicated that the high-density PZT nanocup arrays could have potential applications in ultra-high non-volatile ferroelectric memories (NV-FRAM) or other nanoelectronic devices.

Hydroelastic slamming response in the evolution of a flip-through event during shallow-liquid sloshing

NASA Astrophysics Data System (ADS)

Lugni, C.; Bardazzi, A.; Faltinsen, O. M.; Graziani, G.

2014-03-01

The evolution of a flip-through event [6] upon a vertical, deformable wall during shallow-water sloshing in a 2D tank is analyzed, with specific focus on the role of hydroelasticity. An aluminium plate, whose dimensions are Froude-scaled in order to reproduce the first wet natural frequency associated with the typical structural panel of a Mark III containment system, is used. (Mark III Containment System is a membrane-type tank used in the Liquefied Natural Gas (LNG) carrier to contain the LNG. A typical structural panel is composed by two metallic membranes and two independent thermal insulation layers. The first membrane contains the LNG, the second one ensures redundancy in case of leakage.) Such a system is clamped to a fully rigid vertical wall of the tank at the vertical ends while being kept free on its lateral sides. Hence, in a 2D flow approximation the system can be suitably modelled, as a double-clamped Euler beam, with the Euler beam theory. The hydroelastic effects are assessed by cross-analyzing the experimental data based both on the images recorded by a fast camera, and on the strain measurements along the deformable panel and on the pressure measurements on the rigid wall below the elastic plate. The same experiments are also carried out by substituting the deformable plate with a fully stiff panel. The pressure transducers are mounted at the same positions of the strain gauges used for the deformable plate. The comparison between the results of rigid and elastic case allows to better define the role of hydroelasticity. The analysis has identified three different regimes characterizing the hydroelastic evolution: a quasi-static deformation of the beam (regime I) precedes a strongly hydroelastic behavior (regime II), for which the added mass effects are relevant; finally, the free-vibration phase (regime III) occurs. A hybrid method, combining numerical modelling and experimental data from the tests with fully rigid plate is proposed to examine the hydroelastic effects. Within this approach, the measurements provide the experimental loads acting on the rigid plate, while the numerical solution enables a more detailed analysis, by giving additional information not available from the experimental tests. More in detail, an Euler beam equation is used to model numerically the plate with the added-mass contribution estimated in time. In this way the resulting hybrid method accounts for the variation of the added mass associated with the instantaneous wetted length of the beam, estimated from the experimental images. Moreover, the forcing hydrodynamic load is prescribed by using the experimental pressure distribution measured in the rigid case. The experimental data for the elastic beam are compared with the numerical results of the hybrid model and with those of the standard methods used at the design stage. The comparison against the experimental data shows an overall satisfactory prediction of the hybrid model. The maximum peak pressure predicted by the standard methods agrees with the result of the hybrid model only when the added mass effect is considered. However, the standard methods are not able to properly estimate the temporal evolution of the plate deformation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cavieres, Andres; Al-Haddad, Tristan; Goodman, Joseph

A photovoltaic panel mounting clip comprising a base, central indexing tabs, flanges, lateral indexing tabs, and vertical indexing tabs. The mounting clip removably attaches one or more panels to a beam or the like structure, both mechanically and electrically. It provides secure locking of the panels in all directions, while providing guidance in all directions for accurate installation of the panels to the beam or the like structure.

Laser beam methane detector

NASA Technical Reports Server (NTRS)

Hinkley, E. D., Jr.

1981-01-01

Instrument uses infrared absorption to determine methane concentration in liquid natural gas vapor. Two sensors measure intensity of 3.39 mm laser beam after it passes through gas; absorption is proportional to concentration of methane. Instrument is used in modeling spread of LNG clouds and as leak detector on LNG carriers and installations. Unit includes wheels for mobility and is both vertically and horizontally operable.

Multi-beam laser altimeter

NASA Technical Reports Server (NTRS)

Bufton, Jack L.; Harding, David J.; Ramos-Izquierdo, Luis

1993-01-01

Laser altimetry provides a high-resolution, high-accuracy method for measurement of the elevation and horizontal variability of Earth-surface topography. The basis of the measurement is the timing of the round-trip propagation of short-duration pulses of laser radiation between a spacecraft and the Earth's surface. Vertical resolution of the altimetry measurement is determined primarily by laser pulsewidth, surface-induced spreading in time of the reflected pulse, and the timing precision of the altimeter electronics. With conventional gain-switched pulses from solid-state lasers and sub-nsec resolution electronics, sub-meter vertical range resolution is possible from orbital attitudes of several hundred kilometers. Horizontal resolution is a function of laser beam footprint size at the surface and the spacing between successive laser pulses. Laser divergence angle and altimeter platform height above the surface determine the laser footprint size at the surface, while laser pulse repetition-rate, laser transmitter beam configuration, and altimeter platform velocity determine the space between successive laser pulses. Multiple laser transitters in a singlaltimeter instrument provide across-track and along-track coverage that can be used to construct a range image of the Earth's surface. Other aspects of the multi-beam laser altimeter are discussed.

Ionospheric electron heating, optical emissions, and striations induced by powerful HF radio waves at high latitudes: Aspect angle dependence

NASA Astrophysics Data System (ADS)

Rietveld, M. T.; Kosch, M. J.; Blagoveshchenskaya, N. F.; Kornienko, V. A.; Leyser, T. B.; Yeoman, T. K.

2003-04-01

In recent years, large electron temperature increases of 300% (3000 K above background) caused by powerful HF-radio wave injection have been observed during nighttime using the EISCAT incoherent scatter radar near Tromsø in northern Norway. In a case study we examine the spatial structure of the modified region. The electron heating is accompanied by ion heating of about 100 degrees and magnetic field-aligned measurements show ion outflows increasing with height up to 300 m s-1 at 582 km. The electron density decreases by up to 20%. When the radar antenna was scanned between three elevations from near field-aligned to vertical, the strongest heating effects were always obtained in the field-aligned position. When the HF-pump beam was scanned between the same three positions, the heating was still almost always strongest in the field-aligned direction. Simultaneous images of the 630 nm O(1D) line in the radio-induced aurora showed that the enhancement caused by the HF radio waves also remained localized near the field-aligned position. Coherent HF radar backscatter also appeared strongest when the pump beam was pointed field-aligned. These results are similar to some Langmuir turbulence phenomena which also show a strong preference for excitation by HF rays launched in the field-aligned direction. The correlation of the position of largest temperature enhancement with the position of the radio-induced aurora suggests that a common mechanism, upper-hybrid wave turbulence, is responsible for both effects. Why the strongest heating effects occur for HF rays directed along the magnetic field is still unclear, but self-focusing on field-aligned striations is a candidate mechanism, and possibly ionospheric tilts may be important.

Commissioning of a proton gantry equipped with dual x-ray imagers and a robotic patient positioner, and evaluation of the accuracy of single-beam image registration for this system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Ning; Ghebremedhin, Abiel; Patyal, Baldev, E-mail: bpatyal@llu.eduss

Purpose: To check the accuracy of a gantry equipped with dual x-ray imagers and a robotic patient positioner for proton radiotherapy, and to evaluate the accuracy and feasibility of single-beam registration using the robotic positioner. Methods: One of the proton treatment rooms at their institution was upgraded to include a robotic patient positioner (couch) with 6 degrees of freedom and dual orthogonal kilovoltage x-ray imaging panels. The wander of the proton beam central axis, the wander of the beamline, and the orthogonal image panel crosswires from the gantry isocenter were measured for different gantry angles. The couch movement accuracy andmore » couch wander from the gantry isocenter were measured for couch loadings of 50–300 lb with couch rotations from 0° to ±90°. The combined accuracy of the gantry, couch, and imagers was checked using a custom-made 30 × 30 × 30 cm{sup 3} Styrofoam phantom with beekleys embedded in it. A treatment in this room can be set up and registered at a setup field location, then moved precisely to any other treatment location without requiring additional image registration. The accuracy of the single-beam registration strategy was checked for treatments containing multiple beams with different combinations of gantry angles, couch yaws, and beam locations. Results: The proton beam central axis wander from the gantry isocenter was within 0.5 mm with gantry rotations in both clockwise (CW) and counterclockwise (CCW) directions. The maximum wander of the beamline and orthogonal imager crosswire centers from the gantry isocenter were within 0.5 and 0.8 mm, respectively, with the gantry rotations in CW and CCW directions. Vertical and horizontal couch wanders from the gantry isocenter were within 0.4 and 1.3 mm, respectively, for couch yaw from 0° to ±90°. For a treatment with multiple beams with different gantry angles, couch yaws, and beam locations, the measured displacements of treatment beam locations from the one based on the initial setup beam registered at the gantry at 0°/180° and couch yaw at 0° were within 1.5 mm in three translations and 0.5° in three rotations for a 200 lb couch loading. Conclusions: Results demonstrate that the gantry equipped with a robotic patient positioner and dual imaging panels satisfies treatment requirements for proton radiotherapy. The combined accuracy of the gantry, couch, and imagers allows a patient to be registered at one setup position and then moved precisely to another treatment position by commanding the robotic patient positioner and delivering treatment without requiring additional image registration.« less

Multi-Beam Surface Lidar for Lunar and Planetary Mapping

NASA Technical Reports Server (NTRS)

Bufton, Jack L.; Garvin, James B.

1998-01-01

Surface lidar techniques are now being demonstrated in low Earth orbit with a single beam of pulsed laser radiation at 1064 nm that profiles the vertical structure of Earth surface landforms along the nadir track of a spacecraft. In addition, a profiling laser altimeter, called MOLA, is operating in elliptical Martian orbit and returning surface topography data. These instruments form the basis for suggesting an improved lidar instrument that employs multiple beams for extension of sensor capabilities toward the goal of true, 3-dimensional mapping of the Moon or other similar planetary surfaces. In general the lidar waveform acquired with digitization of a laser echo can be used for laser distance measurement (i.e. range-to-the-surface) by time-of-flight measurement and for surface slope and shape measurements by examining the detailed lidar waveform. This is particularly effective when the intended target is the lunar surface or another planetary body free of any atmosphere. The width of the distorted return pulse is a first order measure of the surface incidence angle, a combination of surface slope and laser beam pointing. Assuming an independent and absolute (with respect to inertial space) measurement of laser beam pointing on the spacecraft, it is possible to derive a surface slope with-respect-to the mean planetary surface or its equipotential gravity surface. Higher-order laser pulse distortions can be interpreted in terms of the vertical relief of the surface or reflectivity variations within the area of the laser beam footprint on the surface.

Image-guided radiotherapy using megavoltage cone-beam computed tomography for treatment of paraspinous tumors in the presence of orthopedic hardware

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hansen, Eric K.; Larson, David A.; Aubin, Michele

Purpose: This report describes a new image-guided radiotherapy (IGRT) technique using megavoltage cone-beam computed tomography (MV-CBCT) to treat paraspinous tumors in the presence of orthopedic hardware. Methods and Materials: A patient with a resected paraspinous high-grade sarcoma was treated to 59.4 Gy with an IMRT plan. Daily MV-CBCT imaging was used to ensure accurate positioning. The displacement between MV-CBCT and planning CT images were determined daily and applied remotely to the treatment couch. The dose-volume histograms of the original and a hypothetical IMRT plan (shifted by the average daily setup errors) were compared to estimate the impact on dosimetry. Results:more » The mean setup corrections in the lateral, longitudinal, and vertical directions were 3.6 mm (95% CI, 2.6-4.6 mm), 4.1 mm (95% CI, 3.2-5.0 mm), and 1.0 mm (95% CI, 0.6-1.3 mm), respectively. Without corrected positioning, the dose to 0.1 cc of the spinal cord increased by 9.4 Gy, and the doses to 95% of clinical target volumes 1 and 2 were reduced by 4 Gy and 4.8 Gy, respectively. Conclusions: Megavoltage-CBCT provides a new alternative image-guided radiotherapy approach for treatment of paraspinous tumors in the presence of orthopedic hardware by providing 3D anatomic information in the treatment position, with clear imaging of metallic objects and without compromising soft-tissue information.« less

Compact Spreader Schemes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Placidi, M.; Jung, J. -Y.; Ratti, A.

2014-07-25

This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibilitymore » when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.« less

Wavelength shift in vertical cavity laser arrays on a patterned substrate

NASA Astrophysics Data System (ADS)

Eng, L. E.; Bacher, K.; Yuen, W.; Larson, M.; Ding, G.; Harris, J. S., Jr.; Chang-Hasnain, C. J.

1995-03-01

The authors demonstrate a spatially chirped emission wavelength in vertical cavity surface emitting laser (VCSEL) arrays grown by molecular beam epitaxy. The wavelength shift is due to a lateral thickness variation in the Al(0.2)Ga(0.8)As cavity, which is induced by a substrate temperature profile during growth. A 20 nm shift in lasing wavelength is obtained in a VCSEL array.

InGaAsN/GaAs Heterostructures for Long-Wavelength Light-Emitting Devices

DTIC Science & Technology

2000-06-23

vertical cavity surface emitting lasers ( VCSELs ) on GaAs is expected to be possible by... molecular beam epitaxy using an RF plasma-source. Broad area and ridge waveguide laser structures based on such QWs exhibit performance that can...work with GaAs/AlAs DBR-mirrors is expected to lead to novel vertical cavity lasers for optical fiber communication systems. Acknowledgement

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

PubMed

Li, Zhaoyang; Kurita, Takashi; Miyanaga, Noriaki

2017-10-20

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

Cephalometric Evaluation of the Hyoid Bone Position in Lebanese Healthy Young Adults.

PubMed

Daraze, Antoine

2018-05-01

The objectives of this study are to assess hyoid sagittal and vertical position, and potential correlations with gender, skeletal class, and anthropometrics. Twenty-seven cephalometric linear, angular, and ratio measurements for the hyoid were recorded on lateral cephalograms obtained from 117 healthy young Lebanese adults. Anthropometric parameters including height, weight, body mass index (BMI), and neck circumference (NC) were measured. Statistically significant gender differences were demonstrated for 21 out of 27 parameters considered. All linear and two out of three angular measurements defining the vertical hyoid position were larger in males compared with females. Five linear, one angular, and two ratio measurements showed differences in the sagittal dimension. Skeletal classes did not influence the sagittal and vertical hyoid position. Anthropometric variables as height were strongly correlated to the vertical hyoid position, while weight correlated more sagittally. Cephalometric norms for hyoid position were established, sexual dimorphism and ethnic differences were demonstrated. Skeletal patterns did not influence the sagittal and vertical hyoid bone position. Anthropometric parameters, such as BMI correlated the least to both vertical and sagittal hyoid position measurements, while the impact of height and weight as separate entities made a paradigm shift providing accurate and strong correlation of the vertical hyoid position to the height, and the sagittal hyoid position to the weight of individuals. The cephalometric norms for the hyoid bone position in the Lebanese population established in the present study are of paramount clinical importance and should be considered in planning combined orthodontic and breathing disorders treatments.

Characteristics and performance of the first commercial multileaf collimator for a robotic radiosurgery system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fürweger, Christoph, E-mail: christoph.fuerweger@cyber-knife.net; Prins, Paulette; Coskan, Harun

Purpose: The “InCise™ multileaf-collimator (MLC)” is the first commercial MLC to be mounted on a robotic SRS/SBRT platform (CyberKnife). The authors assessed characteristics and performance of this novel device in a preclinical five months test period. Methods: Commissioning beam data were acquired with unshielded diodes. EBT3 radiochromic films were employed for measurement of transmission, leaf/bank position accuracy (garden fence) before and after exercising the MLC, for end-to-end testing and further characterization of the beam. The robot workspace with MLC was assessed analytically by transformation to an Euler geometry (“plane,” “gantry,” and “collimator” angles) and by measuring pointing accuracy at eachmore » node. Stability over time was evaluated in picket fence and adapted Winston–Lutz tests (AQA). Results: Beam penumbrae (80%–20%, with 100% = 2 × dose at inflection point for field sizes ≥ 50 × 50 mm{sup 2}) were 2.2–3.7 mm for square fields in reference condition (source-axis-distance 800 mm, depth 15 mm) and depended on field size and off-axis position. Transmission and leakage did not exceed 0.5%. Accessible clinical workspace with MLC covered non-coplanar gantry angles of [−113°; +112°] and collimator angles of [−100°; +107°], with an average robot pointing accuracy of 0.12 ± 0.09 mm. For vertical beams, garden fence tests exhibited an average leaf positioning error of ≤0.2 mm, which increased by 0.25 and 0.30 mm (banks X1 and X2) with leaves traveling parallel to gravity. After execution of a leaf motion stress routine, garden fence tests showed slightly increased jaggedness and allowed to identify one malfunctioning leaf motor. Total system accuracy with MLC was 0.38 ± 0.05 mm in nine end-to-end tests. Picket fence and AQA tests displayed stable results over the test period. Conclusions: The InCise™ MLC for CyberKnife showed high accuracy and adequate characteristics for SRS/SBRT applications. MLC performance after exercise demands specific quality assurance measures.« less

Characteristics and performance of the first commercial multileaf collimator for a robotic radiosurgery system.

PubMed

Fürweger, Christoph; Prins, Paulette; Coskan, Harun; Heijmen, Ben J M

2016-05-01

The "InCise™ multileaf-collimator (MLC)" is the first commercial MLC to be mounted on a robotic SRS/SBRT platform (CyberKnife). The authors assessed characteristics and performance of this novel device in a preclinical five months test period. Commissioning beam data were acquired with unshielded diodes. EBT3 radiochromic films were employed for measurement of transmission, leaf/bank position accuracy (garden fence) before and after exercising the MLC, for end-to-end testing and further characterization of the beam. The robot workspace with MLC was assessed analytically by transformation to an Euler geometry ("plane," "gantry," and "collimator" angles) and by measuring pointing accuracy at each node. Stability over time was evaluated in picket fence and adapted Winston-Lutz tests (AQA). Beam penumbrae (80%-20%, with 100% = 2 × dose at inflection point for field sizes ≥ 50 × 50 mm(2)) were 2.2-3.7 mm for square fields in reference condition (source-axis-distance 800 mm, depth 15 mm) and depended on field size and off-axis position. Transmission and leakage did not exceed 0.5%. Accessible clinical workspace with MLC covered non-coplanar gantry angles of [-113°; +112°] and collimator angles of [-100°; +107°], with an average robot pointing accuracy of 0.12 ± 0.09 mm. For vertical beams, garden fence tests exhibited an average leaf positioning error of ≤0.2 mm, which increased by 0.25 and 0.30 mm (banks X1 and X2) with leaves traveling parallel to gravity. After execution of a leaf motion stress routine, garden fence tests showed slightly increased jaggedness and allowed to identify one malfunctioning leaf motor. Total system accuracy with MLC was 0.38 ± 0.05 mm in nine end-to-end tests. Picket fence and AQA tests displayed stable results over the test period. The InCise™ MLC for CyberKnife showed high accuracy and adequate characteristics for SRS/SBRT applications. MLC performance after exercise demands specific quality assurance measures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riis, Hans L.; Zimmermann, Sune J.; Hjelm-Hansen, Mogens

Purpose: The delivery of high quality stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) treatments to the patient requires knowledge of the position of the isocenter to submillimeter accuracy. To meet the requirements the deviation between the radiation and mechanical isocenters must be less than 1 mm. The use of add-on micromultileaf collimators ({mu}MLCs) in SRS and SRT is an additional challenge to the anticipated high-level geometric and dosimetric accuracy of the treatment. The aim of this work was to quantify the gantry excursions during rotation with and without an add-on {mu}MLC attached to the gantry head. In addition, the shiftmore » in the position of the isocenter and its correlation to the kV beam center of the cone-beam CT system was included in the study. Methods: The quantification of the gantry rotational performance was done using a pointer supported by an in-house made rigid holder attached to the gantry head of the accelerator. The pointer positions were measured using a digital theodolite. To quantify the effect of an {mu}MLC of 50 kg, the measurements were repeated with the {mu}MLC attached to the gantry head. The displacement of the isocenter due to an add-on {mu}MLC of 50 kg was also investigated. In case of the pointer measurement the {mu}MLC was simulated by weights attached to the gantry head. A method of least squares was applied to determine the position and displacement of the mechanical isocenter. Additionally, the displacement of the radiation isocenter was measured using a ball-bearing phantom and the electronic portal image device system. These measurements were based on 8 MV photon beams irradiated onto the ball from the four cardinal angles and two opposed collimator angles. The measurements and analysis of the data were carried out automatically using software delivered by the manufacturer. Results: The displacement of the mechanical isocenter caused by a 50 kg heavy {mu}MLC was found to be (-0.01 {+-} 0.05, -0.10 {+-} 0.03, -0.26 {+-} 0.05) mm in lateral, longitudinal, and vertical direction, respectively. Similarly, the displacement of the radiation isocenter was found to be (0.00 {+-} 0.03, -0.08 {+-} 0.06, -0.32 {+-} 0.02) mm. Good agreement was found between the displacement of the two isocenters. A displacement of the kV cone-beam CT beam center due to the attached weight of 50 kg could not be detected. Conclusions: General characteristics of the gantry arm excursions and displacements caused by an add-on {mu}MLC have been reported. A 50 kg heavy add-on {mu}MLC results in a isocenter displacement downward of 0.26-0.32 mm. The authors recommend that the beam center of the kV cone-beam CT image system should be matched to the isocenter related to the weight of the {mu}MLC. Consequently, the imperfections in isocenter localizations are transferred to the conventional radiotherapy where the clinical consequences of uncertainties in the submillimeter regime are negligible.« less

Beam control of high-power broad-area photonic crystal lasers using ladderlike groove structure

NASA Astrophysics Data System (ADS)

Wang, Tao; Wang, Lijie; Shu, Shili; Tian, Sicong; Lu, Zefeng; Hou, Guanyu; Lu, Huanyu; Tong, Cunzhu; Wang, Lijun

2017-06-01

The high-power broad-area (BA) photonic bandgap crystal (PBC) diode laser is promising as a high-brightness laser source, however, it suffers from poor lateral beam quality owing to the intrinsic drawback of BA lasers. In this paper, a ladderlike groove structure (LLGS) was proposed to improve both the lateral beam quality and emission power of BA PBC lasers. An approximately 15.4% improvement in output power and 25.2% decrease in the lateral beam parameter product (BPP) were realized and the underlying mechanism was discussed. On the basis of the one-dimensional PBC epitaxial structure, a stable vertical far field was demonstrated.

The effect of different foot and hand set-up positions on backstroke start performance.

PubMed

de Jesus, Karla; de Jesus, Kelly; Abraldes, J Arturo; Mourão, Luis; Borgonovo-Santos, Márcio; Medeiros, Alexandre I A; Gonçalves, Pedro; Chainok, Phornpot; Fernandes, Ricardo J; Vaz, Mário A P; Vilas-Boas, João Paulo

2016-11-01

Foot and hand set-up position effects were analysed on backstroke start performance. Ten swimmers randomly completed 27 starts grouped in trials (n = 3) of each variation, changing foot (totally immersed, partially and totally emerged) and hand (lowest, highest horizontal and vertical) positioning. Fifteen cameras recorded kinematics, and four force plates collected hands and feet kinetics. Standardised mean difference and 95% confidence intervals were used. Variations with feet immersed have shown lower vertical centre of mass (CM) set-up position (0.16 m), vertical impulse exerted at the hands, horizontal and vertical impulse exerted at the feet (0.28, 0.41, 0.16 N/BW.s, respectively) than feet emerged with hands horizontal and vertically positioned. Most variations with feet partially emerged exhibited higher and lesser vertical impulse exerted at hands than feet immersed and emerged (e.g. vertical handgrip, 0.13, 0.15 N/BW.s, respectively). Variation with feet emerged and hands on the lowest horizontal handgrip depicted shorter horizontal (0.23, 0.26 m) and vertical CM positioning at flight (0.16, 0.15 m) than the highest horizontal and vertical handgrip, respectively. Start variations have not affected 15-m time. Variations with feet partially or totally emerged depicted advantages, but focusing on the entry and underwater biomechanics is relevant for a shorter start time.

Contrastive Analysis and Research on Negative Pressure Beam Tube System and Positive Pressure Beam Tube System for Mine Use

NASA Astrophysics Data System (ADS)

Wang, Xinyi; Shen, Jialong; Liu, Xinbo

2018-01-01

Against the technical defects of universally applicable beam tube monitoring system at present, such as air suction in the beam tube, line clogging, long sampling time, etc., the paper analyzes the current situation of the spontaneous combustion fire disaster forecast of mine in our country and these defects one by one. On this basis, the paper proposes a research thought that improving the positive pressure beam tube so as to substitute the negative pressure beam tube. Then, the paper introduces the beam tube monitoring system based on positive pressure technology through theoretical analysis and experiment. In the comparison with negative pressure beam tube, the paper concludes the advantage of the new system and draws the conclusion that the positive pressure beam tube is superior to the negative pressure beam tube system both in test result and test time. At last, the paper proposes prospect of the beam tube monitoring system based on positive pressure technology.

Improvements on the accuracy of beam bugs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Y.J.; Fessenden, T.

1998-08-17

At LLNL resistive wall monitors are used to measure the current and position used on ETA-II show a droop in signal due to a fast redistribution time constant of the signals. This paper presents the analysis and experimental test of the beam bugs used for beam current and position measurements in and after the fast kicker. It concludes with an outline of present and future changes that can be made to improve the accuracy of these beam bugs. of intense electron beams in electron induction linacs and beam transport lines. These, known locally as ''beam bugs'', have been used throughoutmore » linear induction accelerators as essential diagnostics of beam current and location. Recently, the development of a fast beam kicker has required improvement in the accuracy of measuring the position of beams. By picking off signals at more than the usual four positions around the monitor, beam position measurement error can be greatly reduced. A second significant source of error is the mechanical variation of the resistor around the bug.« less

Improvements on the accuracy of beam bugs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Y J; Fessenden, T

1998-09-02

At LLNL resistive wall monitors are used to measure the current and position used on ETA-II show a droop in signal due to a fast redistribution time constant of the signals. This paper presents the analysis and experimental test of the beam bugs used for beam current and position measurements in and after the fast kicker. It concludes with an outline of present and future changes that can be made to improve the accuracy of these beam bugs. of intense electron beams in electron induction linacs and beam transport lines. These, known locally as "beam bugs", have been used throughoutmore » linear induction accelerators as essential diagnostics of beam current and location. Recently, the development of a fast beam kicker has required improvement in the accuracy of measuring the position of beams. By picking off signals at more than the usual four positions around the monitor, beam position measurement error can be greatly reduced. A second significant source of error is the mechanical variation of the resistor around the bug.« less

Positive and negative ion beam merging system for neutral beam production

DOEpatents

Leung, Ka-Ngo; Reijonen, Jani

2005-12-13

The positive and negative ion beam merging system extracts positive and negative ions of the same species and of the same energy from two separate ion sources. The positive and negative ions from both sources pass through a bending magnetic field region between the pole faces of an electromagnet. Since the positive and negative ions come from mirror image positions on opposite sides of a beam axis, and the positive and negative ions are identical, the trajectories will be symmetrical and the positive and negative ion beams will merge into a single neutral beam as they leave the pole face of the electromagnet. The ion sources are preferably multicusp plasma ion sources. The ion sources may include a multi-aperture extraction system for increasing ion current from the sources.

If Frisch is true - impacts of varying beam width, resolution, frequency combinations and beam overlap when retrieving liquid water content profiles

NASA Astrophysics Data System (ADS)

Küchler, N.; Kneifel, S.; Kollias, P.; Loehnert, U.

2017-12-01

Cumulus and stratocumulus clouds strongly affect the Earth's radiation budget and are a major uncertainty source in weather and climate prediction models. To improve and evaluate models, a comprehensive understanding of cloud processes is necessary and references are needed. Therefore active and passive microwave remote sensing of clouds can be used to derive cloud properties such as liquid water path and liquid water content (LWC), which can serve as a reference for model evaluation. However, both the measurements and the assumptions when retrieving physical quantities from the measurements involve uncertainty sources. Frisch et al. (1998) combined radar and radiometer observations to derive LWC profiles. Assuming their assumptions are correct, there will be still uncertainties regarding the measurement setup. We investigate how varying beam width, temporal and vertical resolutions, frequency combinations, and beam overlap of and between the two instruments influence the retrieval of LWC profiles. Especially, we discuss the benefit of combining vertically, high resolved radar and radiometer measurements using the same antenna, i.e. having ideal beam overlap. Frisch, A. S., G. Feingold, C. W. Fairall, T. Uttal, and J. B. Snider, 1998: On cloud radar and microwave radiometer measurements of stratus cloud liquid water profiles. J. Geophys. Res.: Atmos., 103 (18), 23 195-23 197, doi:0148-0227/98/98JD-01827509.00.

FIRST BEAM TESTS OF THE APS MBA UPGRADE ORBIT FEEDBACK CONTROLLER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sereno, N. S.; Arnold, N.; Brill, A.

The new orbit feedback system required for the APS multi-bend acromat (MBA) ring must meet challenging beam stability requirements. The AC stability requirement is to correct rms beam motion to 10 % the rms beam size at the insertion device source points from 0.01 to 1000 Hz. The vertical plane represents the biggest challenge for AC stability which is required to be 400 nm rms for a 4 micron vertical beam size. In addition long term drift over a period of 7 days is required to be 1 micron or less at insertion de- vice BPMs and 2 microns formore » arc bpms. We present test re- sults of theMBA prototype orbit feedback controller (FBC) in the APS storage ring. In this test, four insertion device BPMs were configured to send data to the FBC for process- ing into four fast corrector setpoints. The configuration of four bpms and four fast correctors creates a 4-bump and the configuration of fast correctors is similar to what will be implemented in the MBA ring. We report on performance benefits of increasing the sampling rate by a factor of 15 to 22.6 kHz over the existing APS orbit feedback system, lim- itations due to existing storage ring hardware and extrapo- lation to theMBA orbit feedback design. FBC architecture, signal flow and processing design will also be discussed.« less

Mass spectrometer with electron source for reducing space charge effects in sample beam

DOEpatents

Houk, Robert S.; Praphairaksit, Narong

2003-10-14

A mass spectrometer includes an ion source which generates a beam including positive ions, a sampling interface which extracts a portion of the beam from the ion source to form a sample beam that travels along a path and has an excess of positive ions over at least part of the path, thereby causing space charge effects to occur in the sample beam due to the excess of positive ions in the sample beam, an electron source which adds electrons to the sample beam to reduce space charge repulsion between the positive ions in the sample beam, thereby reducing the space charge effects in the sample beam and producing a sample beam having reduced space charge effects, and a mass analyzer which analyzes the sample beam having reduced space charge effects.

Linear positioning laser calibration setup of CNC machine tools

NASA Astrophysics Data System (ADS)

Sui, Xiulin; Yang, Congjing

2002-10-01

The linear positioning laser calibration setup of CNC machine tools is capable of executing machine tool laser calibraiotn and backlash compensation. Using this setup, hole locations on CNC machien tools will be correct and machien tool geometry will be evaluated and adjusted. Machien tool laser calibration and backlash compensation is a simple and straightforward process. First the setup is to 'find' the stroke limits of the axis. Then the laser head is then brought into correct alignment. Second is to move the machine axis to the other extreme, the laser head is now aligned, using rotation and elevation adjustments. Finally the machine is moved to the start position and final alignment is verified. The stroke of the machine, and the machine compensation interval dictate the amount of data required for each axis. These factors determine the amount of time required for a through compensation of the linear positioning accuracy. The Laser Calibrator System monitors the material temperature and the air density; this takes into consideration machine thermal growth and laser beam frequency. This linear positioning laser calibration setup can be used on CNC machine tools, CNC lathes, horizontal centers and vertical machining centers.

Vibrational behavior of adaptive aircraft wing structures modelled as composite thin-walled beams

NASA Technical Reports Server (NTRS)

Song, O.; Librescu, L.; Rogers, C. A.

1992-01-01

The vibrational behavior of cantilevered aircraft wings modeled as thin-walled beams and incorporating piezoelectric effects is studied. Based on the converse piezoelectric effect, the system of piezoelectric actuators conveniently located on the wing yield the control of its associated vertical and lateral bending eigenfrequencies. The possibility revealed by this study enabling one to increase adaptively the eigenfrequencies of thin-walled cantilevered beams could play a significant role in the control of the dynamic response and flutter of wing and rotor blade structures.

Fabrication and characterization of tapered graphite/epoxy box beams

NASA Astrophysics Data System (ADS)

Yen, S.-C.; Gopal, P.; Dharani, L. R.

1993-04-01

Graphite/epoxy (T300/934) prepreg is used to fabricate tapered box beams with a taper angle of 2 deg between the top and bottom walls. The prepreg is cured on a segmented steel core using a hot-press. A screw arrangement is used to apply curing pressure in the horizontal direction, while the platens of the hot-press apply pressure in the vertical direction. The inplane bending stiffness of the beam is determined by 3-point bend test and is found to be in agreement with theory.

Photoluminescence Mapping and Angle-Resolved Photoluminescence of MBE-Grown InGaAs/GaAs RC LED and VCSEL Structures

DTIC Science & Technology

2002-06-03

resonant-cavity light-emitting diodes (RC LEDs) and vertical-cavity surface-emitting lasers ( VCSELs )] fabricated from molecular beam epitaxy (MBE)-grown...grown 8470-631. by molecular beam epitaxy (MBE) using a Riber 32P E-mail address: muszal@ite.waw.pl (0. Muszalski). reactor. Details of the growth can be... molecular beams hit the center of a rotating sion features of RC LED and VCSEL structures, as well sample. However, due to the transversal distribution of as

Development of 1300 nm GaAs-Based Microcavity Light-Emitting Diodes

DTIC Science & Technology

2001-06-01

vertical - cavity surface emitting lasers ( VCSEL ) and micro- cavity light- emitting diodes (MC-LED) for short-to-medium... epitaxial growth run [1 ]. Self-organized In(Ga)As quantum dot (QD) heterostructures grown by molecular beam epitaxy ( MBE ) are promising candidates as...successfully grown by molecular beam epitaxy on GaAs substrates without the need to rely on any in-situ calibration technique. Fabricated

First negative ion beam measurement by the Short-Time Retractable Instrumented Kalorimeter Experiment (STRIKE)

NASA Astrophysics Data System (ADS)

Serianni, G.; De Muri, M.; Muraro, A.; Veltri, P.; Bonomo, F.; Chitarin, G.; Pasqualotto, R.; Pavei, M.; Rizzolo, A.; Valente, M.; Franzen, P.; Ruf, B.; Schiesko, L.

2014-02-01

The Source for Production of Ion of Deuterium Extracted from Rf plasma (SPIDER) test facility is under construction in Padova to optimise the operation of the beam source of ITER neutral beam injectors. The SPIDER beam will be characterised by the instrumented calorimeter STRIKE, whose main components are one-directional carbon-fibre-carbon-composite tiles. A small-scale version of the entire system has been employed in the BAvarian Test MAchine for Negative ions (BATMAN) testbed by arranging two prototype tiles in the vertical direction. The paper presents a description of the mini-STRIKE system and of the data analysis procedures, as well as some results concerning the BATMAN beam under varying operating conditions.

First negative ion beam measurement by the Short-Time Retractable Instrumented Kalorimeter Experiment (STRIKE)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Serianni, G., E-mail: gianluigi.serianni@igi.cnr.it; De Muri, M.; Veltri, P.

2014-02-15

The Source for Production of Ion of Deuterium Extracted from Rf plasma (SPIDER) test facility is under construction in Padova to optimise the operation of the beam source of ITER neutral beam injectors. The SPIDER beam will be characterised by the instrumented calorimeter STRIKE, whose main components are one-directional carbon-fibre-carbon-composite tiles. A small-scale version of the entire system has been employed in the BAvarian Test MAchine for Negative ions (BATMAN) testbed by arranging two prototype tiles in the vertical direction. The paper presents a description of the mini-STRIKE system and of the data analysis procedures, as well as some resultsmore » concerning the BATMAN beam under varying operating conditions.« less

Radar - 449MHz - Forks, WA (FKS) - Raw Data

DOE Data Explorer

Gottas, Daniel

2018-06-25

**Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sounding system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60 m up to 3.5 km for the 449 MHz. **Moments and Spectra.** The raw spectra and moments data are available for all dwells along each beam and are stored in daily files. For each day, there are files labeled "header" and "data." These files are generated by the radar data acquisition system (LAP-XM) and are encoded in a proprietary binary format. Values of spectral density at each Doppler velocity (FFT point), as well as the radial velocity, signal-to-noise ratio, and spectra width for the selected signal peak are included in these files. Attached zip files, *449mhz-spectra-data-extraction.zip* and *449mhz-moment-data-extraction.zip*, include executables to unpack the spectra, (GetSpectra32.exe) and moments (GetMomSp32.exe), respectively. Documentation on usage and output file formats also are included in the zip files.

Radar - 449MHz - North Bend, OR (OTH) - Raw Data

DOE Data Explorer

Gottas, Daniel

2018-06-25

**Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sounding system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60 m up to 3.5 km for the 449 MHz. **Moments and Spectra.** The raw spectra and moments data are available for all dwells along each beam and are stored in daily files. For each day, there are files labeled "header" and "data." These files are generated by the radar data acquisition system (LAP-XM) and are encoded in a proprietary binary format. Values of spectral density at each Doppler velocity (FFT point), as well as the radial velocity, signal-to-noise ratio, and spectra width for the selected signal peak are included in these files. Attached zip files, *449mhz-spectra-data-extraction.zip* and *449mhz-moment-data-extraction.zip*, include executables to unpack the spectra, (GetSpectra32.exe) and moments (GetMomSp32.exe), respectively. Documentation on usage and output file formats also are included in the zip files.

Radar - 449MHz - North Bend, OR (OTH) - Reviewed Data

DOE Data Explorer

Gottas, Daniel

2018-06-25

**Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sounding system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60 m up to 3.5 km for the 449 MHz. **Moments and Spectra.** The raw spectra and moments data are available for all dwells along each beam and are stored in daily files. For each day, there are files labeled "header" and "data." These files are generated by the radar data acquisition system (LAP-XM) and are encoded in a proprietary binary format. Values of spectral density at each Doppler velocity (FFT point), as well as the radial velocity, signal-to-noise ratio, and spectra width for the selected signal peak are included in these files. Attached zip files, *449mhz-spectra-data-extraction.zip* and *449mhz-moment-data-extraction.zip*, include executables to unpack the spectra, (GetSpectra32.exe) and moments (GetMomSp32.exe), respectively. Documentation on usage and output file formats also are included in the zip files.

Radar - 449MHz - Forks, WA (FKS) - Reviewed Data

DOE Data Explorer

Gottas, Daniel

2018-06-25

**Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sounding system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60 m up to 3.5 km for the 449 MHz. **Moments and Spectra.** The raw spectra and moments data are available for all dwells along each beam and are stored in daily files. For each day, there are files labeled "header" and "data." These files are generated by the radar data acquisition system (LAP-XM) and are encoded in a proprietary binary format. Values of spectral density at each Doppler velocity (FFT point), as well as the radial velocity, signal-to-noise ratio, and spectra width for the selected signal peak are included in these files. Attached zip files, *449mhz-spectra-data-extraction.zip* and *449mhz-moment-data-extraction.zip*, include executables to unpack the spectra, (GetSpectra32.exe) and moments (GetMomSp32.exe), respectively. Documentation on usage and output file formats also are included in the zip files.

Radar - 449MHz - Astoria, OR (AST) - Reviewed Data

DOE Data Explorer

Gottas, Daniel

2018-06-25

**Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sounding system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60 m up to 3.5 km for the 449 MHz. **Moments and Spectra.** The raw spectra and moments data are available for all dwells along each beam and are stored in daily files. For each day, there are files labeled "header" and "data." These files are generated by the radar data acquisition system (LAP-XM) and are encoded in a proprietary binary format. Values of spectral density at each Doppler velocity (FFT point), as well as the radial velocity, signal-to-noise ratio, and spectra width for the selected signal peak are included in these files. Attached zip files, *449mhz-spectra-data-extraction.zip* and *449mhz-moment-data-extraction.zip*, include executables to unpack the spectra, (GetSpectra32.exe) and moments (GetMomSp32.exe), respectively. Documentation on usage and output file formats also are included in the zip files.

Radar - 449MHz - Astoria, OR (AST) - Raw Data

DOE Data Explorer

Gottas, Daniel

2018-06-25

**Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sounding system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60 m up to 3.5 km for the 449 MHz. **Moments and Spectra.** The raw spectra and moments data are available for all dwells along each beam and are stored in daily files. For each day, there are files labeled "header" and "data." These files are generated by the radar data acquisition system (LAP-XM) and are encoded in a proprietary binary format. Values of spectral density at each Doppler velocity (FFT point), as well as the radial velocity, signal-to-noise ratio, and spectra width for the selected signal peak are included in these files. Attached zip files, *449mhz-spectra-data-extraction.zip* and *449mhz-moment-data-extraction.zip*, include executables to unpack the spectra, (GetSpectra32.exe) and moments (GetMomSp32.exe), respectively. Documentation on usage and output file formats also are included in the zip files.

An X-ray beam position monitor based on the photoluminescence of helium gas

NASA Astrophysics Data System (ADS)

Revesz, Peter; White, Jeffrey A.

2005-03-01

A new method for white beam position monitoring for both bend magnet and wiggler synchrotron X-ray radiation has been developed. This method utilizes visible light luminescence generated as a result of ionization by the intense X-ray flux. In video beam position monitors (VBPMs), the luminescence of helium gas at atmospheric pressure is observed through a view port using a CCD camera next to the beam line. The beam position, profile, integrated intensity and FWHM are calculated from the distribution of luminescence intensity in each captured image by custom software. Misalignment of upstream apertures changes the image profile making VBPMs helpful for initial alignment of upstream beam line components. VBPMs can thus provide more information about the X-ray beam than most beam position monitors (BPMs). A beam position calibration procedure, employing a tilted plane-parallel glass plate placed in front of the camera lens, has also been developed. The accuracy of the VBPM system was measured during a bench-top experiment to be better than 1 μm. The He-luminescence-based VBPM system has been operative on three CHESS beam lines (F hard-bend and wiggler, A-line wiggler and G-line wiggler) for about a year. The beam positions are converted to analog voltages and used as feedback signals for beam stabilization. In our paper we discuss details of VBPM construction and describe further results of its performance.

Physical properties of meteoroids based on middle and upper atmosphere radar measurements

NASA Astrophysics Data System (ADS)

Gritsevich, M.; Kero, J.; Virtanen, J.; Szasz, C.; Nakamura, T.; Peltoniemi, J.; Koschny, D.

2014-07-01

We present a novel approach to reliably interpret the meteor head-echo scattering measurements detected by the 46.5 MHz MU radar system near Shigaraki, Japan. A meteor head echo is caused by radio waves scattered from the dense region of plasma surrounding and co-moving with a meteoroid during atmospheric flight. The signal Doppler shift and/or range rate of the target can therefore be used to determine meteoroid velocity. The data reduction steps include determining the exact trajectory of the meteoroids entering the observation volume of the antenna beam and calculating meteoroid mass and velocity as a function of time. The model is built using physically-based parametrization. The considered observation volume is narrow, elongated in the vertical direction, and its area of greatest sensitivity covers a circular area of about 10 km diameter at an altitude of 100 km above the radar. Over 100,000 meteor head echoes have been detected over past years of observations. Most of the events are faint with no alternative to be detected visually or with intensified video (ICCD) cameras. In this study we are focusing on objects which have entered the atmosphere with almost vertical trajectories, to ensure the observed segment of the trajectory to be as complete as possible, without loss of its beginning or end part due to beam-pattern-related loss of signal power. The analysis output parameters are range, altitude, radial velocity, meteoroid velocity, instantaneous target position, Radar Cross Section (RCS), meteor radiant, meteoroid ballistic and ablation coefficients, mass loss parameter and meteoroid mass, with possibility to derive other parameters.

Physical Properties of Meteoroids based on Middle and Upper Atmosphere Radar Measurements

NASA Astrophysics Data System (ADS)

Gritsevich, Maria; Nakamura, Takuji; Kero, Johan; Szasz, Csilla; Virtanen, Jenni; Peltoniemi, Jouni; Koschny, Detlef

We present a novel approach to reliably interpret the meteor head echo scattering measurements detected by the 46.5 MHz MU radar system near Shigaraki, Japan. A meteor head echo is caused by radio waves scattered from the dense region of plasma surrounding and co-moving with a meteoroid during atmospheric flight. The signal Doppler shift and/or range rate of the target can therefore be used to determine meteoroid velocity. The data reduction steps include determining the exact trajectory of the meteoroids entering the observation volume of the antenna beam and calculating meteoroid mass and velocity as a function of time. The model is built using physically based parameterization. The considered observation volume is narrow, elongated in the vertical direction, and its area of greatest sensitivity covers a circular area of about 10 km diameter at an altitude of 100 km above the radar. Over 100000 meteor head echoes have been detected over past years of observations. Most of the events are faint with no alternative to be detected visually or with intensified video (ICCD) cameras. In this study we are focusing on objects which have entered the atmosphere with almost vertical trajectories, to ensure the observed segment of the trajectory to be as complete as possible, without loss of its beginning or end part due to beam-pattern related loss of signal power. The analysis output parameters are range, altitude, radial velocity, meteoroid velocity, instantaneous target position, Radar Cross Section (RCS), meteor radiant, meteoroid ballistic and ablation coefficients, mass loss parameter and meteoroid mass, with possibility to derive other parameters.

Fabrication of Silicon Backshort Assembly for Waveguide-Coupled Superconducting Detectors

NASA Technical Reports Server (NTRS)

Crowe, E.; Bennett, C. L.; Chuss, D. T.; Denis, K. L.; Eimer, J.; Lourie, N.; Marriage, T.; Moseley, S. H.; Rostem, K.; Stevenson, T. R.;

Analysis of the light-water flooding of the HFBR thimble tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carew, J.F.; Aronson, A.L.; Cokinos, D.M.

The fuel elements surrounding the central vertical thimble tubes in the Brookhaven National Laboratory High-Flux Beam Reactor (HFBR) are highly undermoderated, and light-water flooding of these irradiation thimbles results in a positive core reactivity insertion. The light-water contamination of the D{sub 2}O thimble tube coolant is the result of a postulated double-ended guillotine break of a U tube in the experimental facilities heat exchanger during the HFBR light-water flooding (LWF) event. While this event has a low probability (1.3 x 10{sup {minus}4}/yr), the HFBR protection system must ensure adequate thermal margin during the power transient. This paper summarizes the analysismore » of the HFBR thimble-tube LWF event.« less

Atmospheric aerosol profiling with a bistatic imaging lidar system.

PubMed

Barnes, John E; Sharma, N C Parikh; Kaplan, Trevor B

2007-05-20

Atmospheric aerosols have been profiled using a simple, imaging, bistatic lidar system. A vertical laser beam is imaged onto a charge-coupled-device camera from the ground to the zenith with a wide-angle lens (CLidar). The altitudes are derived geometrically from the position of the camera and laser with submeter resolution near the ground. The system requires no overlap correction needed in monostatic lidar systems and needs a much smaller dynamic range. Nighttime measurements of both molecular and aerosol scattering were made at Mauna Loa Observatory. The CLidar aerosol total scatter compares very well with a nephelometer measuring at 10 m above the ground. The results build on earlier work that compared purely molecular scattered light to theory, and detail instrument improvements.

Development of X-ray CCD camera based X-ray micro-CT system

NASA Astrophysics Data System (ADS)

Sarkar, Partha S.; Ray, N. K.; Pal, Manoj K.; Baribaddala, Ravi; Agrawal, Ashish; Kashyap, Y.; Sinha, A.; Gadkari, S. C.

2017-02-01

Availability of microfocus X-ray sources and high resolution X-ray area detectors has made it possible for high resolution microtomography studies to be performed outside the purview of synchrotron. In this paper, we present the work towards the use of an external shutter on a high resolution microtomography system using X-ray CCD camera as a detector. During micro computed tomography experiments, the X-ray source is continuously ON and owing to the readout mechanism of the CCD detector electronics, the detector registers photons reaching it during the read-out period too. This introduces a shadow like pattern in the image known as smear whose direction is defined by the vertical shift register. To resolve this issue, the developed system has been incorporated with a synchronized shutter just in front of the X-ray source. This is positioned in the X-ray beam path during the image readout period and out of the beam path during the image acquisition period. This technique has resulted in improved data quality and hence the same is reflected in the reconstructed images.

Investigation of fabrication process for sub 20-nm dense pattern of non-chemically amplified electron beam resist based on acrylic polymers

NASA Astrophysics Data System (ADS)

Ochiai, Shunsuke; Takayama, Tomohiro; Kishimura, Yukiko; Asada, Hironori; Sonoda, Manae; Iwakuma, Minako; Hoshino, Ryoichi

2016-10-01

In this study, we examine exposure characteristics of a positive tone electron beam resist consisting of methyl α- chloroacrylate and α-methylstyrene by changing the development process conditions. 25/25 nm and 30/30 nm line-andspace (L/S) patterns (design value) are developed in amyl and heptyl acetates. The resist patterns developed at 0ºC for 120 s show the better shapes having the vertical sidewalls than those developed at 22 °C for 60 s. The dose margins of pattern formation for 0°C development become wider, although the sensitivities are lower. The effect of post exposure baking (PEB) on exposure characteristics is also investigated. Adding PEB process performed at 120°C for 2 min, the dose margin also becomes wider although the sensitivity is lower. 20/20 nm L/S patterns are fabricated by using PEB and/or 0°C development. Though the required exposure dose is larger, the resist pattern is improved by PEB and/or 0°C development. The formation of 35 nm pitch pattern is also presented.

Tunable bistable devices for harvesting energy from spinning wheels

NASA Astrophysics Data System (ADS)

Elhadidi, Mohamed; Helal, Mohammed; Nassar, Omar; Arafa, Mustafa; Zeyada, Yasser

2015-04-01

Bistable systems have recently been employed for vibration energy harvesting owing to their favorable dynamic characteristics and desirable response for wideband excitation. In this paper, we investigate the use of bistable harvesters to extract energy from spinning wheels. The proposed harvester consists of a piezoelectric cantilever beam that is mounted on a rigid spinning hub and carries a tip mass in the form of a permanent magnet. Magnetic repulsion forces from an opposite magnet cause the beam to possess two stable equilibrium positions. Inter-well lead-lag oscillations caused by rotation in a vertical plane provide a good source for energy extraction. The design offers frequency tuning, as the centrifugal forces strain the harvester, thereby increasing its natural frequency to cope with a variable rotational speed. This has applications in self-powered sensors mounted on spinning wheels, such as tire pressure monitoring sensors. An effort is made to select the design parameters to enable the harvester to exhibit favorable inter-well oscillations across a range of rotational speeds for enhanced energy harvesting. Findings of the present work are verified both numerically and experimentally.

Orbit Correction for the Newly Developed Polarization-Switching Undulator

NASA Astrophysics Data System (ADS)

Obina, Takashi; Honda, Tohru; Shioya, Tatsuro; Kobayashi, Yukinori; Tsuchiya, Kimichika; Yamamoto, Shigeru

2007-01-01

A new scheme of undulator magnet arrangements has been proposed and developed as a polarization-switching radiation source, and its test-stand was installed in the 2.5-GeV Photon Factory storage ring (PF ring) in order to investigate the effects on the beam orbit. The closed orbit distortion (COD) over 200 μm was produced in a vertical direction when we switched the polarization of the radiation from the test-stand. In a horizontal direction, the COD was less than 50μm. The results agreed well with the predictions from the magnetic-field measurement on the bench. In order to suppress the CODs and realize a stable operation of the ring with the polarization-switching, we developed an orbit correction system which consists of an encoder to detect motion of magnets, a pair of beam position monitors (BPMs), signal processing parts, and a pair of steering magnets. We succeeded in suppressing the CODs to the level below 3μm using the system even when we switch the polarization at a maximum frequency of 0.8 Hz.

SIMULATIONS OF BOOSTER INJECTION EFFICIENCY FOR THE APS-UPGRADE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calvey, J.; Borland, M.; Harkay, K.

2017-06-25

The APS-Upgrade will require the injector chain to provide high single bunch charge for swap-out injection. One possible limiting factor to achieving this is an observed reduction of injection efficiency into the booster synchrotron at high charge. We have simulated booster injection using the particle tracking code elegant, including a model for the booster impedance and beam loading in the RF cavities. The simulations point to two possible causes for reduced efficiency: energy oscillations leading to losses at high dispersion locations, and a vertical beam size blowup caused by ions in the Particle Accumulator Ring. We also show that themore » efficiency is much higher in an alternate booster lattice with smaller vertical beta function and zero dispersion in the straight sections.« less

830-nm Polarization Controlled Lasing of InGaAs Quantum Wire Vertical-Cavity Surface-Emitting Lasers Grown on (775)B GaAs Substrates by Molecular Beam Epitaxy

NASA Astrophysics Data System (ADS)

Higuchi, Yu; Osaki, Shinji; Sasahata, Yoshifumi; Kitada, Takahiro; Shimomura, Satoshi; Ogura, Mutsuo; Hiyamizu, Satoshi

2007-02-01

We report the first demonstration of room temperature (RT) current injection lasing of vertical-cavity surface-emitting lasers (VCSELs), with self-organized InGaAs/(GaAs)6(AlAs)1 quantum wires (QWRs) in their active region, grown on (775)B-oriented GaAs substrates by molecular beam epitaxy. A (775)B InGaAs QWR-VCSEL with an aperture diameter of 4 μm lased at a wavelength of 829.7 nm and a threshold current of 0.7 mA at RT. The light output was linearly polarized in the direction parallel to the QWRs due to optical anisotropy of the self-organized (775)B InGaAs QWRs.

SU-E-T-377: Inaccurate Positioning Might Introduce Significant MapCheck Calibration Error in Flatten Filter Free Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, S; Chao, C; Columbia University, NY, NY

2014-06-01

Purpose: This study investigates the calibration error of detector sensitivity for MapCheck due to inaccurate positioning of the device, which is not taken into account by the current commercial iterative calibration algorithm. We hypothesize the calibration is more vulnerable to the positioning error for the flatten filter free (FFF) beams than the conventional flatten filter flattened beams. Methods: MapCheck2 was calibrated with 10MV conventional and FFF beams, with careful alignment and with 1cm positioning error during calibration, respectively. Open fields of 37cmx37cm were delivered to gauge the impact of resultant calibration errors. The local calibration error was modeled as amore » detector independent multiplication factor, with which propagation error was estimated with positioning error from 1mm to 1cm. The calibrated sensitivities, without positioning error, were compared between the conventional and FFF beams to evaluate the dependence on the beam type. Results: The 1cm positioning error leads to 0.39% and 5.24% local calibration error in the conventional and FFF beams respectively. After propagating to the edges of MapCheck, the calibration errors become 6.5% and 57.7%, respectively. The propagation error increases almost linearly with respect to the positioning error. The difference of sensitivities between the conventional and FFF beams was small (0.11 ± 0.49%). Conclusion: The results demonstrate that the positioning error is not handled by the current commercial calibration algorithm of MapCheck. Particularly, the calibration errors for the FFF beams are ~9 times greater than those for the conventional beams with identical positioning error, and a small 1mm positioning error might lead to up to 8% calibration error. Since the sensitivities are only slightly dependent of the beam type and the conventional beam is less affected by the positioning error, it is advisable to cross-check the sensitivities between the conventional and FFF beams to detect potential calibration errors due to inaccurate positioning. This work was partially supported by a DOD Grant No.; DOD W81XWH1010862.« less

Beam position monitor for energy recovered linac beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powers, Thomas; Evtushenko, Pavel

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

Variation of Shrinkage Strain within the Depth of Concrete Beams.

PubMed

Jeong, Jong-Hyun; Park, Yeong-Seong; Lee, Yong-Hak

2015-11-16

The variation of shrinkage strain within beam depth was examined through four series of time-dependent laboratory experiments on unreinforced concrete beam specimens. Two types of beam specimens, horizontally cast and vertically cast, were tested; shrinkage variation was observed in the horizontally cast specimens. This indicated that the shrinkage variation within the beam depth was due to water bleeding and tamping during the placement of the fresh concrete. Shrinkage strains were measured within the beam depth by two types of strain gages, surface-attached and embedded. The shrinkage strain distribution within the beam depth showed a consistent tendency for the two types of gages. The test beams were cut into four sections after completion of the test, and the cutting planes were divided into four equal sub-areas to measure the aggregate concentration for each sub-area of the cutting plane. The aggregate concentration increased towards the bottom of the beam. The shrinkage strain distribution was estimated by Hobbs' equation, which accounts for the change of aggregate volume concentration.

Variation of Shrinkage Strain within the Depth of Concrete Beams

PubMed Central

Jeong, Jong-Hyun; Park, Yeong-Seong; Lee, Yong-Hak

2015-01-01

The variation of shrinkage strain within beam depth was examined through four series of time-dependent laboratory experiments on unreinforced concrete beam specimens. Two types of beam specimens, horizontally cast and vertically cast, were tested; shrinkage variation was observed in the horizontally cast specimens. This indicated that the shrinkage variation within the beam depth was due to water bleeding and tamping during the placement of the fresh concrete. Shrinkage strains were measured within the beam depth by two types of strain gages, surface-attached and embedded. The shrinkage strain distribution within the beam depth showed a consistent tendency for the two types of gages. The test beams were cut into four sections after completion of the test, and the cutting planes were divided into four equal sub-areas to measure the aggregate concentration for each sub-area of the cutting plane. The aggregate concentration increased towards the bottom of the beam. The shrinkage strain distribution was estimated by Hobbs’ equation, which accounts for the change of aggregate volume concentration. PMID:28793677

MBE growth and processing of III/V-nitride semiconductor thin film structures: Growth of gallium indium arsenic nitride and nano-machining with focused ion beam and electron beam

NASA Astrophysics Data System (ADS)

Park, Yeonjoon

The advanced semiconductor material InGaAsN was grown with nitrogen plasma assisted Molecular Beam Epitaxy (MBE). The InGaAsN layers were characterized with High Resolution X-ray Diffraction (HRXDF), Atomic Fore Microscope (AFM), X-ray Photoemission Spectroscopy (XPS) and Photo-Luminescence (PL). The reduction of the band gap energy was observed with the incorporation of nitrogen and the lattice matched condition to the GaAs substrate was achieved with the additional incorporation of indium. A detailed investigation was made for the growth mode changes from planar layer-by-layer growth to 3D faceted growth with a higher concentration of nitrogen. A new X-ray diffraction analysis was developed and applied to the MBE growth on GaAs(111)B, which is one of the facet planes of InGaAsN. As an effort to enhance the processing tools for advanced semiconductor materials, gas assisted Focused Ion Beam (FIB) vertical milling was performed on GaN. The FIB processed area shows an atomically flat surface, which is good enough for the fabrication of Double Bragg Reflector (DBR) mirrors for the Blue GaN Vertical Cavity Surface Emitting Laser (VCSEL) Diodes. An in-situ electron beam system was developed to combine the enhanced lithographic processing capability with the atomic layer growth capability by MBE. The electron beam system has a compensation capability against substrate vibration and thermal drift. In-situ electron beam lithography was performed with the low pressure assisting gas. The advanced processing and characterization methods developed in this thesis will assist the development of superior semiconductor materials for the future.

Slamming pressures on the bottom of a free-falling vertical wedge

NASA Astrophysics Data System (ADS)

Ikeda, C. M.; Judge, C. Q.

2013-11-01

High-speed planing boats are subjected to repeat impacts due to slamming, which can cause structural damage and injury to passengers. A first step in understanding and predicting the physics of a craft re-entering the water after becoming partially airborne is an experimental vertical drop test of a prismastic wedge (deadrise angle, β =20° beam, B = 300 mm; and length, L = 600 mm). The acrylic wedge was mounted to a rig allowing it to free-fall into a deep-water tank (5.2m × 5.2m × 4.2m deep) from heights 0 <= H <= 635 mm, measured from the keel to the free surface. The wedge was instrumented to record vertical position, acceleration, and pressure on the bottom surface. A pressure mapping system, capable of measuring several points over the area of the thin (0.1 mm) film sensor at sampling rates up to 20 kHz, is used and compared to surface-mounted pressure transducers (sampled at 10 kHz). A high speed camera (1000 fps, resolution of 1920 × 1200 pixels) is mounted above the wedge model to record the wetted surface as the wedge descended below the free surface. The pressure measurements taken with both conventional surface pressure transducers and the pressure mapping system agree within 10% of the peak pressure values (0.7 bar, typical). Supported by the Office of Naval Research.

Effect of gyro verticality error on lateral autoland tracking performance for an inertially smoothed control law

NASA Technical Reports Server (NTRS)

Thibodeaux, J. J.

1977-01-01

The results of a simulation study performed to determine the effects of gyro verticality error on lateral autoland tracking and landing performance are presented. A first order vertical gyro error model was used to generate the measurement of the roll attitude feedback signal normally supplied by an inertial navigation system. The lateral autoland law used was an inertially smoothed control design. The effect of initial angular gyro tilt errors (2 deg, 3 deg, 4 deg, and 5 deg), introduced prior to localizer capture, were investigated by use of a small perturbation aircraft simulation. These errors represent the deviations which could occur in the conventional attitude sensor as a result of the maneuver-induced spin-axis misalinement and drift. Results showed that for a 1.05 deg per minute erection rate and a 5 deg initial tilt error, ON COURSE autoland control logic was not satisfied. Failure to attain the ON COURSE mode precluded high control loop gains and localizer beam path integration and resulted in unacceptable beam standoff at touchdown.

Technical Note: Dosimetric effects of couch position variability on treatment plan quality with an MRI-guided Co-60 radiation therapy machine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chow, Phillip E., E-mail: pechow@mednet.ucla.edu

2016-08-15

Purpose: Magnetic resonance imaging (MRI) guidance in radiation therapy brings real-time imaging and adaptive planning into the treatment vault where it can account for interfraction and intrafraction movement of soft tissue. The only commercially available MRI-guided radiation therapy device is a three-head {sup 60}Co and MRI system with an integrated treatment planning system (TPS). Couch attenuation of the beam of up to 20% is well modeled in the TPS. Variations in the patient’s day-to-day position introduce discrepancies in the actual couch attenuation as modeled in the treatment plan. For this reason, the authors’ institution avoids plans with beams that passmore » through or near the couch edges. This study investigates the effects of differential beam attenuation by the couch due to couch shifts in order to determine whether couch edge avoidance restrictions can be lifted. Couch shifts were simulated using a Monte Carlo treatment planning system and ion chamber measurements performed for validation. Methods: A total of 27 plans from 23 patients were investigated. Couch shifts of 1 and 2 cm were introduced in combinations of lateral and vertical directions to simulate patient position variations giving 16 shifted plans per reference plan. The 1 and 2 cm shifts were based on shifts recorded in 320 treatment fractions. Results: Following TG176 recommendations for measurement methods, couch attenuation measurements agreed with TPS modeled attenuation to within 2.1%. Planning target volume D95 changed less than 1% for 1 and 2 cm couch shifts in only the x-direction and less than 3% for all directions. Conclusions: Dosimetry of all plans tested was robust to couch shifts up to ±2 cm. In general, couch shifts resulted in clinically insignificant dosimetric deviations. It is conceivable that in certain cases with large systematic couch shifts and plans that are particularly sensitive to shifts, dosimetric changes might rise to a clinically significant level.« less

Apparatus for precision focussing and positioning of a beam waist on a target

NASA Technical Reports Server (NTRS)

Lynch, Dana H. (Inventor); Gunter, William D. (Inventor); Mcalister, Kenneth W. (Inventor)

1991-01-01

The invention relates to optical focussing apparatus and, more particularly, to optical apparatus for focussing a highly collimated Gaussian beam which provides independent and fine control over the focus waist diameter, the focus position both along the beam axis and transverse to the beam, and the focus angle. A beam focussing and positioning apparatus provides focussing and positioning for the waist of a waisted beam at a desired location on a target such as an optical fiber. The apparatus includes a first lens, having a focal plane f sub 1, disposed in the path of an incoming beam and a second lens, having a focal plane f sub 2 and being spaced downstream from the first lens by a distance at least equal to f sub 1 + 10 f sub 2, which cooperates with the first lens to focus the waist of the beam on the target. A rotatable optical device, disposed upstream of the first lens, adjusts the angular orientation of the beam waist. The transverse position of the first lens relative to the axis of the beam is varied to control the transverse position of the beam waist relative to the target (a fiber optic as shown) while the relative axial positions of the lenses are varied to control the diameter of the beam waist and to control the axial position of the beam waist. Mechanical controllers C sub 1, C sub 2, C sub 3, C sub 4, and C sub 5 control the elements of the optical system. How seven adjustments can be made to correctly couple a laser beam into an optical fiber is illustrated. Prior art systems employing optical techniques to couple a laser beam into an optical fiber or other target simply do not provide the seven necessary adjustments. The closest known prior art, a Newport coupler, provides only two of the seven required adjustments.

Mujarrah Canal Bridge, Ramadi, Iraq

DTIC Science & Technology

2009-07-14

eastern span (Span No. 1) of the structure. The detonation caused damage to the pier cap (the beam across the column top) of Bent No. 1 and post-tensioned...damage to the existing bridge, the temporary jacking and support of the existing structure, construction of the post-tensioned concrete beams and...placed directly onto the precast -concrete pans; and vertical offsets between the individual precast -concrete deck pans. Also, SIGIR identified

Measurement of inclusive muon pair production by 225-GeV/c. pi. /sup +/,. pi. /sup -/, and proton beams with a large acceptance spectrometers. [Cross sections, 225 GeV/c, tables

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brason, J G

1977-05-01

Inclusive muon pair production by 225 GeV/c ..pi../sup +/, ..pi../sup -/ and proton beams incident upon carbon and tin targets was measured over a large range of kinematic variables (2m/sub ..mu../ < m/sub ..mu mu.. < 1 GeV/c/sup 2/, 0 < x/sub F/ < 1, P/sub perpendicular to/ < 4 GeV/c and vertical bar cos theta* vertical bar < .3). The value of the invariant cross section E d/sup 4/sigma/dmdx/sub f/dp/sup 2//sub perpendicular to/ is presented as a function of these variables. The vector mesons rho, ..omega.., phi, J and psi' appear in the data along with apparently nonresonant ..mu..-pairs.more » By looking for additional muons accompanying J ..-->.. ..mu../sup +/..mu../sup -/ events, a 1.0% upper limit on production of pairs of charmed particles in association with the J is obtained. Aspects of the continuum muon pair data are compared to Drell-Yan model calculations. The ratio of ..mu..-pairs produced by ..pi../sup +/ beam particles to ..mu..-pairs produced by ..pi../sup -/ beam particles supports electromagnetic production at high mass.« less

Single-atom detection of isotopes

DOEpatents

Meyer, Fred W.

2002-01-01

A method for performing accelerator mass spectrometry, includes producing a beam of positive ions having different multiple charges from a multicharged ion source; selecting positive ions having a charge state of from +2 to +4 to define a portion of the beam of positive ions; and scattering at least a portion of the portion of the beam of positive ions off a surface of a target to directly convert a portion of the positive ions in the portion of the beam of positive ions to negative ions.

The New Dual-beam Spectropluviometer Concept

NASA Astrophysics Data System (ADS)

Delahaye, J. Y.; Barthes, L.; Golé, P.; Lavergnat, J.; Vinson, J. P.

A Dual Beam Spectropluviometer (DBS) measuring the equivalent diameter D, the vertical velocity V and the time T of arrival of particles is presented. Its main advan- tage over previous optical disdrometers is the extensive measurement range of atmo- spheric precipitations near ground. In particular, 0.15 mm diameter particles can be observed in quiet laboratory conditions and 0.2 mm is the smallest diameter observed in the outdoor turbulent air velocity field. The means for obtaining such results are (i) two uniform beams of rectangular cross-section 2 mm in height, 40 mm in width and 250 mm in length, with a 2 mm vertical gap, (ii) a dual 16-bit analog to digital converter, (iii) a dedicated program for extracting the 3 parameters in real time by computing the signal slopes and determining the correlation between both channels, (iii) various means for reducing splashing and vibration. Laboratory tests and typical rain measurements are shown. The DBS is particularly suited for extensive atmospheric and radio propagation research applications where the smallest drops were not correctly estimated in the distributions because of the lack of appropriate measurement devices.

Manifestations of geometric phases in a proton electric-dipole-moment experiment in an all-electric storage ring

NASA Astrophysics Data System (ADS)

Silenko, Alexander J.

2017-12-01

We consider a proton electric-dipole-moment experiment in an all-electric storage ring when the spin is frozen and local longitudinal and vertical electric fields alternate. In this experiment, the geometric (Berry) phases are very important. Due to the these phases, the spin rotates about the radial axis. The corresponding systematic error is rather important while it can be canceled with clockwise and counterclockwise beams. The geometric phases also lead to the spin rotation about the radial axis. This effect can be canceled with clockwise and counterclockwise beams as well. The sign of the azimuthal component of the angular velocity of the spin precession depends on the starting point where the spin orientation is perfect. The radial component of this quantity keeps its value and sign for each starting point. When the longitudinal and vertical electric fields are joined in the same sections without any alternation, the systematic error due to the geometric phases does not appear but another systematic effect of the spin rotation about the azimuthal axis takes place. It has opposite signs for clockwise and counterclockwise beams.

The EDOP radar system on the high-altitude NASA ER-2 aircraft

USGS Publications Warehouse

Heymsfield, G.M.; Bidwell, S.W.; Caylor, I.J.; Ameen, S.; Nicholson, S.; Boncyk, W.; Miller, L.; Vandemark, D.; Racette, P.E.; Dod, L.R.

1996-01-01

The NASA ER-2 high-altitude (20 km) aircraft that emulates a satellite view of precipitation systems carries a variety of passive and active (lidar) remote sensing instruments. A new Doppler weather radar system at X band (9.6 GHz) called the ER-2 Doppler radar (EDOP) has been developed and flown on the ER-2 aircraft. EDOP is a fully coherent Doppler weather radar with fixed nadir and forward pointing (33?? off nadir) beams that map out Doppler winds and reflectivities in the vertical plane along the aircraft motion vector. Doppler winds from the two beams can be used to derive vertical and along-track air motions. In addition, the forward beam provides linear depolarization measurements that are useful in discriminating microphysical characteristics of the precipitation. This paper deals with a general description of the EDOP instrument including the measurement concept, the system configuration and hardware, and recently obtained data examples from the instrument. The combined remote sensing package on the ER-2, along with EDOP, provides a unique platform for simulating spaceborne remote sensing of precipitation.

Effects of vertical positioning on gas exchange and lung volumes in acute respiratory distress syndrome.

PubMed

Richard, Jean-Christophe M; Maggiore, Salvatore Maurizio; Mancebo, Jordi; Lemaire, François; Jonson, Bjorn; Brochard, Laurent

2006-10-01

Supine position may contribute to the loss of aerated lung volume in patients with acute respiratory distress syndrome (ARDS). We hypothesized that verticalization increases lung volume and improves gas exchange by reducing the pressure surrounding lung bases. Prospective observational physiological study in a medical ICU. In 16 patients with ARDS we measured arterial blood gases, pressure-volume curves of the respiratory system recorded from positive-end expiratory pressure (PEEP), and changes in lung volume in supine and vertical positions (trunk elevated at 45 degrees and legs down at 45 degrees ). Vertical positioning increased PaO(2) significantly from 94+/-33 to 142+/-49 mmHg, with an increase higher than 40% in 11 responders. The volume at 20 cmH(2)O measured on the PV curve from PEEP increased using the vertical position only in responders (233+/-146 vs. -8+/-9 1ml in nonresponders); this change was correlated to oxygenation change (rho=0.55). End-expiratory lung volume variation from supine to vertical and 1 h later back to supine, measured in 12 patients showed a significant increase during the 1-h upright period in responders (n=7) but not in nonresponders (n=5; 215+/-220 vs. 10+/-22 ml), suggesting a time-dependent recruitment. Vertical positioning is a simple technique that may improve oxygenation and lung recruitment in ARDS patients.

Design and performance of coded aperture optical elements for the CESR-TA x-ray beam size monitor

NASA Astrophysics Data System (ADS)

Alexander, J. P.; Chatterjee, A.; Conolly, C.; Edwards, E.; Ehrlichman, M. P.; Flanagan, J. W.; Fontes, E.; Heltsley, B. K.; Lyndaker, A.; Peterson, D. P.; Rider, N. T.; Rubin, D. L.; Seeley, R.; Shanks, J.

2014-12-01

We describe the design and performance of optical elements for an x-ray beam size monitor (xBSM), a device measuring e+ and e- beam sizes in the CESR-TA storage ring. The device can measure vertical beam sizes of 10 - 100 μm on a turn-by-turn, bunch-by-bunch basis at e± beam energies of 2 - 5 GeV. x-rays produced by a hard-bend magnet pass through a single- or multiple-slit (coded aperture) optical element onto a detector. The coded aperture slit pattern and thickness of masking material forming that pattern can both be tuned for optimal resolving power. We describe several such optical elements and show how well predictions of simple models track measured performances.

Multimode laser beam analyzer instrument using electrically programmable optics.

PubMed

Marraccini, Philip J; Riza, Nabeel A

2011-12-01

Presented is a novel design of a multimode laser beam analyzer using a digital micromirror device (DMD) and an electronically controlled variable focus lens (ECVFL) that serve as the digital and analog agile optics, respectively. The proposed analyzer is a broadband laser characterization instrument that uses the agile optics to smartly direct light to the required point photodetectors to enable beam measurements of minimum beam waist size, minimum waist location, divergence, and the beam propagation parameter M(2). Experimental results successfully demonstrate these measurements for a 500 mW multimode test laser beam with a wavelength of 532 nm. The minimum beam waist, divergence, and M(2) experimental results for the test laser are found to be 257.61 μm, 2.103 mrad, 1.600 and 326.67 μm, 2.682 mrad, 2.587 for the vertical and horizontal directions, respectively. These measurements are compared to a traditional scan method and the results of the beam waist are found to be within error tolerance of the demonstrated instrument.

Optical mode engineering and high power density per facet length (>8.4 kW/cm) in tilted wave laser diodes

NASA Astrophysics Data System (ADS)

Ledentsov, N. N.; Shchukin, V. A.; Maximov, M. V.; Gordeev, N. Y.; Kaluzhniy, N. A.; Mintairov, S. A.; Payusov, A. S.; Shernyakov, Yu. M.

2016-03-01

Tilted Wave Lasers (TWLs) based on optically coupled thin active waveguide and thick passive waveguide offer an ultimate solution for thick-waveguide diode laser, preventing catastrophic optical mirror damage and thermal smile in laser bars, providing robust operation in external cavity modules thus enabling wavelength division multiplexing and further increase in brightness enabling direct applications of laser diodes in the mainstream material processing. We show that by proper engineering of the waveguide one can realize high performance laser diodes at different tilt angles of the vertical lobes. Two vertical lobes directed at various angles (namely, +/-27° or +/-9°) to the junction plane are experimentally realized by adjusting the compositions and the thicknesses of the active and the passive waveguide sections. The vertical far field of a TWL with the two +/-9° vertical beams allows above 95% of all the power to be concentrated within a vertical angle below 25°, the fact which is important for laser stack applications using conventional optical coupling schemes. The full width at half maximum of each beam of the value of 1.7° evidences diffraction- limited operation. The broad area (50 μm) TWL chips at the cavity length of 1.5 mm reveal a high differential efficiency ~90% and a current-source limited pulsed power >42W for as-cleaved TWL device. Thus the power per facet length in a laser bar in excess of 8.4 kW/cm can be realized. Further, an ultimate solution for the smallest tilt angle is that where the two vertical lobes merge forming a single lobe directed at the zero angle is proposed.

14 CFR 27.1393 - Minimum intensities in any vertical plane of forward and rear position lights.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Minimum intensities in any vertical plane of forward and rear position lights. 27.1393 Section 27.1393 Aeronautics and Space FEDERAL AVIATION... Equipment Lights § 27.1393 Minimum intensities in any vertical plane of forward and rear position lights...

14 CFR 29.1393 - Minimum intensities in any vertical plane of forward and rear position lights.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Minimum intensities in any vertical plane of forward and rear position lights. 29.1393 Section 29.1393 Aeronautics and Space FEDERAL AVIATION... Equipment Lights § 29.1393 Minimum intensities in any vertical plane of forward and rear position lights...

14 CFR 25.1393 - Minimum intensities in any vertical plane of forward and rear position lights.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Minimum intensities in any vertical plane of forward and rear position lights. 25.1393 Section 25.1393 Aeronautics and Space FEDERAL AVIATION... Equipment Lights § 25.1393 Minimum intensities in any vertical plane of forward and rear position lights...

33 CFR 84.03 - Vertical positioning and spacing of lights.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Vertical positioning and spacing... Vertical positioning and spacing of lights. (a) On a power-driven vessel of 20 meters or more in length the... is carried, then that light, at a height above the hull of not less than 5 meters, and, if the...

33 CFR 84.03 - Vertical positioning and spacing of lights.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Vertical positioning and spacing... Vertical positioning and spacing of lights. (a) On a power-driven vessel of 20 meters or more in length the... is carried, then that light, at a height above the hull of not less than 5 meters, and, if the...

33 CFR 84.03 - Vertical positioning and spacing of lights.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Vertical positioning and spacing... Vertical positioning and spacing of lights. (a) On a power-driven vessel of 20 meters or more in length the... is carried, then that light, at a height above the hull of not less than 5 meters, and, if the...

33 CFR 84.03 - Vertical positioning and spacing of lights.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Vertical positioning and spacing... Vertical positioning and spacing of lights. (a) On a power-driven vessel of 20 meters or more in length the... is carried, then that light, at a height above the hull of not less than 5 meters, and, if the...

GPS vertical axis performance enhancement for helicopter precision landing approach

NASA Technical Reports Server (NTRS)

Denaro, Robert P.; Beser, Jacques

1986-01-01

Several areas were investigated for improving vertical accuracy for a rotorcraft using the differential Global Positioning System (GPS) during a landing approach. Continuous deltaranging was studied and the potential improvement achieved by estimating acceleration was studied by comparing the performance on a constant acceleration turn and a rough landing profile of several filters: a position-velocity (PV) filter, a position-velocity-constant acceleration (PVAC) filter, and a position-velocity-turning acceleration (PVAT) filter. In overall statistics, the PVAC filter was found to be most efficient with the more complex PVAT performing equally well. Vertical performance was not significantly different among the filters. Satellite selection algorithms based on vertical errors only (vertical dilution of precision or VDOP) and even-weighted cross-track and vertical errors (XVDOP) were tested. The inclusion of an altimeter was studied by modifying the PVAC filter to include a baro bias estimate. Improved vertical accuracy during degraded DOP conditions resulted. Flight test results for raw differential results excluding filter effects indicated that the differential performance significantly improved overall navigation accuracy. A landing glidepath steering algorithm was devised which exploits the flexibility of GPS in determining precise relative position. A method for propagating the steering command over the GPS update interval was implemented.

Non-deterministic quantum CNOT gate with double encoding

NASA Astrophysics Data System (ADS)

Gueddana, Amor; Attia, Moez; Chatta, Rihab

2013-09-01

We define an Asymmetric Partially Polarizing Beam Splitter (APPBS) to be a linear optical component having different reflectivity (transmittance) coefficients, on the upper and the lower arms, for horizontally and vertically Polarized incident photons. Our CNOT model is composed by two APPBSs, one Half Wave Plate (HWP), two Polarizing Beam Splitters (PBSs), a Beam Splitter (BS) and a -phase rotator for specific wavelength. Control qubit operates with dual rail encoding while target qubit is based on polarization encoding. To perform CNOT operation in 4/27 of the cases, input and target incoming photons are injected with different wavelengths.

A variable partially polarizing beam splitter.

PubMed

Flórez, Jefferson; Carlson, Nathan J; Nacke, Codey H; Giner, Lambert; Lundeen, Jeff S

2018-02-01

We present designs for variably polarizing beam splitters. These are beam splitters allowing the complete and independent control of the horizontal and vertical polarization splitting ratios. They have quantum optics and quantum information applications, such as quantum logic gates for quantum computing and non-local measurements for quantum state estimation. At the heart of each design is an interferometer. We experimentally demonstrate one particular implementation, a displaced Sagnac interferometer configuration, that provides an inherent instability to air currents and vibrations. Furthermore, this design does not require any custom-made optics but only common components which can be easily found in an optics laboratory.

A variable partially polarizing beam splitter

NASA Astrophysics Data System (ADS)

Flórez, Jefferson; Carlson, Nathan J.; Nacke, Codey H.; Giner, Lambert; Lundeen, Jeff S.

2018-02-01

We present designs for variably polarizing beam splitters. These are beam splitters allowing the complete and independent control of the horizontal and vertical polarization splitting ratios. They have quantum optics and quantum information applications, such as quantum logic gates for quantum computing and non-local measurements for quantum state estimation. At the heart of each design is an interferometer. We experimentally demonstrate one particular implementation, a displaced Sagnac interferometer configuration, that provides an inherent instability to air currents and vibrations. Furthermore, this design does not require any custom-made optics but only common components which can be easily found in an optics laboratory.

Beam-based measurement of the center of the new STAR pipe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robert-Demolaize, G.

During the RHIC Shutdown preceding Run13 for polarized protons, various upgrades were brought to the STAR detector, one of which being the partial installation of the Forward GEM Tracker (FGT). This installation includes a new beam pipe at the center of the detector with an internal radius half the size of what the replaced pipe was, from 40 mm to 20 mm. The following reviews the results of a vertical aperture scans in the STAR interaction region performed at injection energy with both beams, and gives an estimate of the measured transverse offset of the new STAR pipe.

Existence of Torsional Solitons in a Beam Model of Suspension Bridge

NASA Astrophysics Data System (ADS)

Benci, Vieri; Fortunato, Donato; Gazzola, Filippo

2017-11-01

This paper studies the existence of solitons, namely stable solitary waves, in an idealized suspension bridge. The bridge is modeled as an unbounded degenerate plate, that is, a central beam with cross sections, and displays two degrees of freedom: the vertical displacement of the beam and the torsional angles of the cross sections. Under fairly general assumptions, we prove the existence of solitons. Under the additional assumption of large tension in the sustaining cables, we prove that these solitons have a nontrivial torsional component. This appears relevant for security since several suspension bridges collapsed due to torsional oscillations.

Communication using VCSEL laser array

NASA Technical Reports Server (NTRS)

Goorjian, Peter M. (Inventor)

2008-01-01

Ultrafast directional beam switching, using coupled vertical cavity surface emitting lasers (VCSELs) is combined with a light modulator to provide information transfer at bit rates of tens of GHz. This approach is demonstrated to achieve beam switching frequencies of 32-50 GHz in some embodiments and directional beam switching with angular differences of about eight degrees. This switching scheme is likely to be useful for ultrafast optical networks at frequencies much higher than achievable with other approaches. A Mach-Zehnder interferometer, a Fabry-Perot etalon, or a semiconductor-based electro-absorption transmission channel, among others, can be used as a light modulator.

Profiling of MOCVD- and MBE-grown VCSEL wafers for WDM sources

NASA Astrophysics Data System (ADS)

Sze, Theresa; Mahbobzadeh, A. M.; Cheng, Julian; Hersee, Stephen D.; Osinski, Marek; Brueck, Steven R. J.; Malloy, Kevin J.

1993-06-01

We compare vertical-cavity surface emitting lasers grown by molecular beam epitaxial methods to those grown by metal organic chemical vapor deposition methods as sources for wavelength-division multiplexing systems.

Sub-Pixel Accuracy Crack Width Determination on Concrete Beams in Load Tests by Triangle Mesh Geometry Analysis

NASA Astrophysics Data System (ADS)

Liebold, F.; Maas, H.-G.

2018-05-01

This paper deals with the determination of crack widths of concrete beams during load tests from monocular image sequences. The procedure starts in a reference image of the probe with suitable surface texture under zero load, where a large number of points is defined by an interest operator. Then a triangulated irregular network is established to connect the points. Image sequences are recorded during load tests with the load increasing continuously or stepwise, or at intermittently changing load. The vertices of the triangles are tracked through the consecutive images of the sequence with sub-pixel accuracy by least squares matching. All triangles are then analyzed for changes by principal strain calculation. For each triangle showing significant strain, a crack width is computed by a thorough geometric analysis of the relative movement of the vertices.

Room temperature lasing of GaAs quantum wire vertical-cavity surface-emitting lasers grown on (7 7 5) B GaAs substrates by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Higuchi, Y.; Osaki, S.; Kitada, T.; Shimomura, S.; Takasuka, Y.; Ogura, M.; Hiyamizu, S.

2006-06-01

Self-organized GaAs/(GaAs) 4(AlAs) 2 quantum wires (QWRs) grown on (7 7 5) B-oriented GaAs substrates by molecular beam epitaxy have been applied to an active region of vertical-cavity surface-emitting lasers (VCSELs). The (7 7 5) B GaAs QWR-VCSEL with an aperture diameter of 3 μm lased at a wavelength of 765 nm with a threshold current of 0.38 mA at room temperature. This is the first demonstration of laser operation of the QWR-VCSEL by current injection. The light output was linearly polarized in the direction parallel to the QWRs due to the optical anisotropy of the self-organized (7 7 5) B GaAs QWRs.

Off-line commissioning of EBIS and plans for its integration into ATLAS and CARIBU.

PubMed

Ostroumov, P N; Barcikowski, A; Dickerson, C A; Mustapha, B; Perry, A; Sharamentov, S I; Vondrasek, R C; Zinkann, G

2016-02-01

An Electron Beam Ion Source Charge Breeder (EBIS-CB) has been developed at Argonne to breed radioactive beams from the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne Tandem Linac Accelerator System (ATLAS). The EBIS-CB will replace the existing ECR charge breeder to increase the intensity and significantly improve the purity of reaccelerated radioactive ion beams. The CARIBU EBIS-CB has been successfully commissioned offline with an external singly charged cesium ion source. The performance of the EBIS fully meets the specifications to breed rare isotope beams delivered from CARIBU. The EBIS is being relocated and integrated into ATLAS and CARIBU. A long electrostatic beam transport system including two 180° bends in the vertical plane has been designed. The commissioning of the EBIS and the beam transport system in their permanent location will start at the end of this year.

Off-line commissioning of EBIS and plans for its integration into ATLAS and CARIBU

NASA Astrophysics Data System (ADS)

Ostroumov, P. N.; Barcikowski, A.; Dickerson, C. A.; Mustapha, B.; Perry, A.; Sharamentov, S. I.; Vondrasek, R. C.; Zinkann, G.

2016-02-01

An Electron Beam Ion Source Charge Breeder (EBIS-CB) has been developed at Argonne to breed radioactive beams from the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne Tandem Linac Accelerator System (ATLAS). The EBIS-CB will replace the existing ECR charge breeder to increase the intensity and significantly improve the purity of reaccelerated radioactive ion beams. The CARIBU EBIS-CB has been successfully commissioned offline with an external singly charged cesium ion source. The performance of the EBIS fully meets the specifications to breed rare isotope beams delivered from CARIBU. The EBIS is being relocated and integrated into ATLAS and CARIBU. A long electrostatic beam transport system including two 180° bends in the vertical plane has been designed. The commissioning of the EBIS and the beam transport system in their permanent location will start at the end of this year.

Transmission beam characteristics of a Risso's dolphin (Grampus griseus).

PubMed

Smith, Adam B; Kloepper, Laura N; Yang, Wei-Cheng; Huang, Wan-Hsiu; Jen, I-Fan; Rideout, Brendan P; Nachtigall, Paul E

2016-01-01

The echolocation system of the Risso's dolphin (Grampus griseus) remains poorly studied compared to other odontocete species. In this study, echolocation signals were recorded from a stationary Risso's dolphin with an array of 16 hydrophones and the two-dimensional beam shape was explored using frequency-dependent amplitude plots. Click source parameters were similar to those already described for this species. Centroid frequency of click signals increased with increasing sound pressure level, while the beamwidth decreased with increasing center frequency. Analysis revealed primarily single-lobed, and occasionally vertically dual-lobed, beam shapes. Overall beam directivity was found to be greater than that of the harbor porpoise, bottlenose dolphin, and a false killer whale. The relationship between frequency content, beam directivity, and head size for this Risso's dolphin deviated from the trend described for other species. These are the first reported measurements of echolocation beam shape and directivity in G. griseus.

High-resolution study of dynamical diffraction phenomena accompanying the Renninger (222/113) case of three-beam diffraction in silicon

PubMed Central

Kazimirov, A.; Kohn, V. G.

2010-01-01

X-ray optical schemes capable of producing a highly monochromatic beam with high angular collimation in both the vertical and horizontal planes have been evaluated and utilized to study high-resolution diffraction phenomena in the Renninger (222/113) case of three-beam diffraction in silicon. The effect of the total reflection of the incident beam into the nearly forbidden reflected beam was observed for the first time with the maximum 222 reflectivity at the 70% level. We have demonstrated that the width of the 222 reflection can be varied many times by tuning the azimuthal angle by only a few µrad in the vicinity of the three-beam diffraction region. This effect, predicted theoretically more than 20 years ago, is explained by the enhancement of the 222 scattering amplitude due to the virtual two-stage 000 113 222 process which depends on the azimuthal angle. PMID:20555185

Electron cloud buildup driving spontaneous vertical instabilities of stored beams in the Large Hadron Collider

NASA Astrophysics Data System (ADS)

Romano, Annalisa; Boine-Frankenheim, Oliver; Buffat, Xavier; Iadarola, Giovanni; Rumolo, Giovanni

2018-06-01

At the beginning of the 2016 run, an anomalous beam instability was systematically observed at the CERN Large Hadron Collider (LHC). Its main characteristic was that it spontaneously appeared after beams had been stored for several hours in collision at 6.5 TeV to provide data for the experiments, despite large chromaticity values and high strength of the Landau-damping octupole magnet. The instability exhibited several features characteristic of those induced by the electron cloud (EC). Indeed, when LHC operates with 25 ns bunch spacing, an EC builds up in a large fraction of the beam chambers, as revealed by several independent indicators. Numerical simulations have been carried out in order to investigate the role of the EC in the observed instabilities. It has been found that the beam intensity decay is unfavorable for the beam stability when LHC operates in a strong EC regime.

Effects associated with nanostructure fabrication using in situ liquid cell TEM technology

DOE PAGES

Chen, Xin; Zhou, Lihui; Wang, Ping; ...

2015-07-28

We studied silicon, carbon, and SiC x nanostructures fabricated using liquid-phase electron-beam-induced deposition technology in transmission electron microscopy systems. Nanodots obtained from fixed electron beam irradiation followed a universal size versus beam dose trend, with precursor concentrations from pure SiCl 4 to 0 % SiCl 4 in CH 2Cl 2, and electron beamintensity ranges of two orders of magnitude, showing good controllability of the deposition. Secondary electrons contributed to the determination of the lateral sizes of the nanostructures, while the primary beam appeared to have an effect in reducing the vertical growth rate. These results can be used to generatemore » donut-shaped nanostructures. Using a scanning electron beam, line structures with both branched and unbranched morphologies were also obtained. As a result, the liquid-phase electron-beam induced deposition technology is shown to be an effective tool for advanced nanostructured material generation.« less

Plane hydroelastic beam vibrations due to uniformly moving one axle vehicle

NASA Astrophysics Data System (ADS)

Fleischer, D.; Park, S.-K.

2004-06-01

The hydroelastic vibrations of a beam with rectangular cross-section is analyzed under the effect of an uniformly moving single axle vehicle using modal analysis and two-dimensional potential flow theory of the fluid neglecting the effect of surface waves aside the beam. For the special case of homogeneous beam resting on the surface of a water filled prismatic basin, the normal modes are determined considering surface waves in beam direction under the condition of compensating the volume of the enclosed fluid. The way to determine the vertical acceleration of the single axle vehicle is shown, which governs the response of the system. As analysis results the course of wheel load, the surface waves along the beam and the flow velocity distribution of the fluid is demonstrated for a continuous floating bridge under the passage of a rolling mass moving with uniform speed.

Meteorological effects on laser propagation for power transmission

NASA Technical Reports Server (NTRS)

Beverly, R. E., III

1982-01-01

An examination of possible laser operating parameters for power transmission to earth from solar power satellites is presented, with particular attention paid to assuring optimal delivery at midlatitudes. The degradation of beam efficiency due to molecular scattering, molecular absorption, aerosol scattering, and aerosol absorption during beam propagation through the atmosphere can be alleviated by judicious choice of wavelength windows, elevating the receptor sites, using a vertical propagation path, or by hole boring, i.e., vaporizing the aerosol particles in the beam path. Analyses are given for the beam propagation through fog, haze, clouds, and snow using various transitions. Only weapons-quality lasers are seen as being capable of boring through clouds and aerosols, employing a CW beam with superimposed pulses at high power densities. It is concluded that further short wavelength transmission experiments be performed to demonstrate transmission feasibility with the CW/pulsed mode of beam propagation.

Electron beam pumped semiconductor laser

NASA Technical Reports Server (NTRS)

Hug, William F. (Inventor); Reid, Ray D. (Inventor)

2009-01-01

Electron-beam-pumped semiconductor ultra-violet optical sources (ESUVOSs) are disclosed that use ballistic electron pumped wide bandgap semiconductor materials. The sources may produce incoherent radiation and take the form of electron-beam-pumped light emitting triodes (ELETs). The sources may produce coherent radiation and take the form of electron-beam-pumped laser triodes (ELTs). The ELTs may take the form of electron-beam-pumped vertical cavity surface emitting lasers (EVCSEL) or edge emitting electron-beam-pumped lasers (EEELs). The semiconductor medium may take the form of an aluminum gallium nitride alloy that has a mole fraction of aluminum selected to give a desired emission wavelength, diamond, or diamond-like carbon (DLC). The sources may be produced from discrete components that are assembled after their individual formation or they may be produced using batch MEMS-type or semiconductor-type processing techniques to build them up in a whole or partial monolithic manner, or combination thereof.

The application of laser triangulation method on the blind guidance

NASA Astrophysics Data System (ADS)

Wu, Jih-Huah; Wang, Jinn-Der; Fang, Wei; Shan, Yi-Chia; Ma, Shih-Hsin; Kao, Hai-Ko; Jiang, Joe-Air; Lee, Yun-Parn

2011-08-01

A new apparatus for blind-guide is proposed in this paper. Optical triangulation method was used to realize the system. The main components comprise a notebook computer, a camera and two laser modules. One laser module emits a light line beam on the vertical axis. Another laser module emits a light line beam on the tilt horizontal axis. The track of the light line beam on the ground or on the object is captured by the camera, and the image is sent to the notebook computer for calculation. The system can calculate the object width and the distance between the object and the blind in terms of the light line positions on the image. Based on the experiment, the distance between the test object and the blind can be measured with a standard deviation of less than 3% within the range of 60 to 150 cm. The test object width can be measured with a standard deviation of less than 1% within the range of 60 to 150 cm. For saving the power consumption, the laser modules are switched on/off with a trigger pulse. And for reducing the complex computation, the two laser modules are switched on alternately. Besides this, a band pass filter is used to filter out the signal except the specific laser light, which can increase the signal to noise ratio.

Ku-band multiple beam antenna

NASA Technical Reports Server (NTRS)

Chen, C. C.; Franklin, C. F.

1980-01-01

The frequency reuse capability is demonstrated for a Ku-band multiple beam antenna which provides contiguous low sidelobe spot beams for point-to-point communications between any two points within the continental United States (CONUS), or regional coverage beams for direct broadcast systems. A spot beam antenna in the 14/21 GHz band which provides contiguous overlapping beams covering CONUS and two discrete beams covering Hawaii and Alaska were designed, developed, and tested. Two reflector antennas are required for providing contiguous coverage of CONUS. Each is comprised of one offset parabolic reflector, one flat polarization diplexer, and two separate planar array feeds. This antenna system provides contiguous spot beam coverage of CONUS, utilizing 15 beams. Also designed, developed and demonstrated was a shaped contoured beam antenna system which provides contiguous four time zone coverage of CONUS from a single offset parabolic reflector incorporating one flat polarization diplexer and two separate planar array feeds. The beams which illuminate the eastern time zone and the mountain time zone are horizontally polarized, while the beams which illuminate the central time zone and the pacific time zone are vertically polarized. Frequency reuse is achieved by amplitude and polarization isolation.

mA beam acceleration efforts on 100 MeV H- cyclotron at CIAE

NASA Astrophysics Data System (ADS)

Zhang, Tianjue; An, Shizhong; Lv, Yinlong; Ge, Tao; Jia, Xianlu; Ji, Bin; Yin, Zhiguo; Pan, Gaofeng; Cao, Lei; Guan, Fengping; Yang, Jianjun; Li, Zhenguo; Zhao, Zhenlu; Wu, Longcheng; Zhang, He; Wang, Jingfeng; Zhang, Yiwang; Liu, Jingyuan; Li, Shiqiang; Lu, Xiaotong; Liu, Zhenwei; Li, Yaoqian; Guo, Juanjuan; Cao, Xuelong; Guan, Leilei; Wang, Fei; Wang, Yang; Yang, Guang; Zhang, Suping; Hou, Shigang; Wang, Feng

2017-09-01

Various technologies for high current compact H- cyclotron have been developed at CIAE since 1990s. A 375 μA proton beam was extracted from a 30 MeV compact H- cyclotron CYCIAE-30 at the end of 1994. A central region model cyclotron CYCIAE-CRM was developed for the design verification of a 100 MeV high current compact H- cyclotron CYCIAE-100. It is also a 10 MeV proton machine as a prototype for PET application. A 430 μA beam was achieved in 2009. The first beam was extracted from the CYCIAE-100 cyclotron on July 4, 2014, the operation stability has been improved and beam current has been increased gradually. A 1.1 mA proton beam was measured on the internal target in July 2016. The effort for an increasing of proton beam has continued till now. In this paper, the effort on several aspects for mA beam development will be presented, including the multi-cusp source, buncher, matching from the energy of the injected beam, vertical beam line and central region, beam loading of the RF system and instrumentation for beam diagnostics etc.

Nanopillar Photonic Crystal Lasers for Tb/s Transceivers on Silicon

DTIC Science & Technology

2015-07-09

dimensions of NWs can be adjusted by lithographically patterned nanoholes on dielectric mask. Some studies of SAE growth on Si using Ga droplets, i.e. Ga...inside the patterned nanoholes . In this study, the effects of seeding layer growth temperature on uniformity, vertical yield, and optical...thermal silicon dioxide (SiO2). Next, E-Beam resist ZEP520A was coated and nanoholes were patterned by E-Beam lithography (EBL). The designed diameter

15. Detail, lower chord connection point on downstream side, showing ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

15. Detail, lower chord connection point on downstream side, showing pinned connection of lower chord eye bars, laced vertical compression member, diagonal eye bar tension members, turnbuckled diagonal counters, and floor beam. Note also timber floor stringers supported by floor beam, and exposed ends of timber deck members visible at left above lower chord eye bar. View to northwest. - Dry Creek Bridge, Spanning Dry Creek at Cook Road, Ione, Amador County, CA

Shiqaq Hai Musalla Primary Healthcare Center, Kirkuk, Iraq: Sustainment Assessment

DTIC Science & Technology

2009-04-13

show any indicators of failure. The floors appeared even and level, and there were no apparent signs of settlement or displacement. During the...failure. The floors appeared even and level, and there were no apparent signs of settlement or displacement. With the exception of the walls tributary... settlement . The walls above the cantilever beams over the portico to the building had vertical cracks that aligned with the beam supports below

Improved Electro-Optical Switches

NASA Technical Reports Server (NTRS)

Nelson, Bruce N.; Cooper, Ronald F.

1994-01-01

Improved single-pole, double-throw electro-optical switches operate in switching times less than microsecond developed for applications as optical communication systems and networks of optical sensors. Contain no moving parts. In comparison with some prior electro-optical switches, these are simpler and operate with smaller optical losses. Beam of light switched from one output path to other by applying, to electro-optical crystal, voltage causing polarization of beam of light to change from vertical to horizontal.

Beam position reconstruction for the g2p experiment in Hall A at Jefferson lab

NASA Astrophysics Data System (ADS)

Zhu, Pengjia; Allada, Kalyan; Allison, Trent; Badman, Toby; Camsonne, Alexandre; Chen, Jian-ping; Cummings, Melissa; Gu, Chao; Huang, Min; Liu, Jie; Musson, John; Slifer, Karl; Sulkosky, Vincent; Ye, Yunxiu; Zhang, Jixie; Zielinski, Ryan

2016-02-01

Beam-line equipment was upgraded for experiment E08-027 (g2p) in Hall A at Jefferson Lab. Two beam position monitors (BPMs) were necessary to measure the beam position and angle at the target. A new BPM receiver was designed and built to handle the low beam currents (50-100 nA) used for this experiment. Two new super-harps were installed for calibrating the BPMs. In addition to the existing fast raster system, a slow raster system was installed. Before and during the experiment, these new devices were tested and debugged, and their performance was also evaluated. In order to achieve the required accuracy (1-2 mm in position and 1-2 mrad in angle at the target location), the data of the BPMs and harps were carefully analyzed, as well as reconstructing the beam position and angle event by event at the target location. The calculated beam position will be used in the data analysis to accurately determine the kinematics for each event.

Are the new starting block facilities beneficial for backstroke start performance?

PubMed

de Jesus, Karla; de Jesus, Kelly; Abraldes, J Arturo; Medeiros, Alexandre Igor Araripe; Fernandes, Ricardo J; Vilas-Boas, João Paulo

2016-01-01

We aimed to analyse the handgrip positioning and the wedge effects on the backstroke start performance and technique. Ten swimmers completed randomly eight 15 m backstroke starts (four with hands on highest horizontal and four on vertical handgrip) performed with and without wedge. One surface and one underwater camera recorded kinematic data. Standardised mean difference (SMD) and 95% confidence intervals (CI) were used. Handgrip positioning did not affect kinematics with and without wedge use. Handgrips horizontally positioned and feet over wedge displayed greater knee angular velocity than without it (SMD = -0.82; 95% CI: -1.56, -0.08). Hands vertically positioned and feet over wedge presented greater take-off angle (SMD = -0.81; 95% CI: -1.55, -0.07), centre of mass (CM) vertical positioning at first water contact (SMD = -0.97; 95% CI: -1.87, -0.07) and CM vertical velocity at CM immersion (SMD = 1.03; 95% CI: 0.08, 1.98) when comparing without wedge use. Swimmers extended the hip previous to the knee and ankle joints, except for the variant with hands vertically positioned without wedge (SMD = 0.75; 95% CI: -0.03, 1.53). Swimmers should preserve biomechanical advantages achieved during flight with variant with hands vertically positioned and wedge throughout entry and underwater phase.

Single crystal CVD diamond membranes as Position Sensitive X-ray Detector

NASA Astrophysics Data System (ADS)

Desjardins, K.; Menneglier, C.; Pomorski, M.

2017-12-01

Transparent X-ray Beam Position Monitor (XBPM) has been specifically developed for low energy X-ray beamlines (1.4 keV < E < 5 keV) allowing to transmit more than 80% of 2 keV energy beam. The detector is based on a free-standing single crystal CVD diamond membrane of 4 μm thickness with position-sensitive DLC (Diamond-Like Carbon) resistive electrodes in duo-lateral configuration. The measured X-ray beam induced current (XBIC) due to the interaction of X-rays with diamond membrane allows precise monitoring of the absolute beam flux and the beam position (by the reconstruction of its center-of-gravity) at beam transmissions reaching 95%. This detector has been installed at SOLEIL synchrotron on the SIRIUS beamline monochromator output and it has shown charge collection efficiency (CCE) reaching 100% with no lag-effects and excellent beam intensity sensitivity monitoring. X-ray beam mapping of the detector showed an XBIC response inhomogeneity of less than 10% across the membrane, corresponding mainly to the measured variation of the diamond plate thickness. The measured beam position resolution is at sub-micron level depending on the beam flux and the readout electronics bandwidth.

Radar - ESRL Wind Profiler with RASS, Wasco Airport - Derived Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCaffrey, Katherine

Profiles of turbulence dissipation rate for 15-minute intervals, time-stamped at the beginning of the 15-minute period, during the final 30 minutes of each hour. During that time, the 915-MHz wind profiling radar was in an optimized configuration with a vertically pointing beam only for measuring accurate spectral widths of vertical velocity. A bias-corrected dissipation rate also was profiled (described in McCaffrey et al. 2017). Hourly files contain two 15-minute profiles.

Implant treatment planning regarding augmentation procedures: panoramic radiographs vs. cone beam computed tomography images.

PubMed

Dagassan-Berndt, Dorothea C; Zitzmann, Nicola U; Walter, Clemens; Schulze, Ralf K W

2016-08-01

To evaluate the impact of cone beam computed tomography (CBCT) imaging on treatment planning regarding augmentation procedures for implant placement. Panoramic radiographs and CBCT images of 40 patients requesting single-tooth implants in 59 sites were retrospectively analyzed by six specialists in implantology, and treatment planning was performed. Therapeutic recommendations were compared with the surgical protocol performed initially. Bone height estimation from panoramic radiographs yielded to higher measures and greater variability compared to CBCT. The suggested treatment plan for lateral and vertical augmentation procedures based on CBCT or panoramic radiographs coincided for 55-72% of the cases. A trend to a more invasive augmentation procedure was seen when planning was based on CBCT. Panoramic radiography revealed 57-63% (lateral) vs. 67% (vertical augmentation) congruent plans in agreement with surgery. Among the dissenting sites, there was a trend toward less invasive planning for lateral augmentation with panoramic radiographs, while vertical augmentation requirements were more frequently more invasive when based on CBCT. Vertical augmentation requirements can be adequately determined from panoramic radiographs. In difficult cases with a deficient lateral alveolar bone, the augmentation schedule may better be evaluated from CBCT to avoid underestimation, which occurs more frequently when based on panoramic radiographs only. However, overall, radiographic interpretation and diagnostic thinking accuracy seem to be mainly depending on the opinion of observers. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Behaviour of Plate Anchorage in Plate-Reinforced Composite Coupling Beams

PubMed Central

Lam, W. Y.; Li, Lingzhi; Su, R. K. L.; Pam, H. J.

2013-01-01

As a new alternative design, plate-reinforced composite (PRC) coupling beam achieves enhanced strength and ductility by embedding a vertical steel plate into a conventionally reinforced concrete (RC) coupling beam. Based on a nonlinear finite element model developed in the authors' previous study, a parametric study presented in this paper has been carried out to investigate the influence of several key parameters on the overall performance of PRC coupling beams. The effects of steel plate geometry, span-to-depth ratio of beams, and steel reinforcement ratios at beam spans and in wall regions are quantified. It is found that the anchorage length of the steel plate is primarily controlled by the span-to-depth ratio of the beam. Based on the numerical results, a design curve is proposed for determining the anchorage length of the steel plate. The load-carrying capacity of short PRC coupling beams with high steel ratio is found to be controlled by the steel ratio of wall piers. The maximum shear stress of PRC coupling beams should be limited to 15 MPa. PMID:24288465

Long bunch trains measured using a prototype cavity beam position monitor for the Compact Linear Collider

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cullinan, F. J.; Boogert, S. T.; Farabolini, W.

2015-11-19

The Compact Linear Collider (CLIC) requires beam position monitors (BPMs) with 50 nm spatial resolution for alignment of the beam line elements in the main linac and beam delivery system. Furthermore, the BPMs must be able to make multiple independent measurements within a single 156 ns long bunch train. A prototype cavity BPM for CLIC has been manufactured and tested on the probe beam line at the 3rd CLIC Test Facility (CTF3) at CERN. The transverse beam position is determined from the electromagnetic resonant modes excited by the beam in the two cavities of the pickup, the position cavity and the referencemore » cavity. The mode that is measured in each cavity resonates at 15 GHz and has a loaded quality factor that is below 200. Analytical expressions for the amplitude, phase and total energy of signals from long trains of bunches have been derived and the main conclusions are discussed. The results of the beam tests are presented. The variable gain of the receiver electronics has been characterized using beam excited signals and the form of the signals for different beam pulse lengths with the 2/3 ns bunch spacing has been observed. The sensitivity of the reference cavity signal to charge and the horizontal position signal to beam offset have been measured and are compared with theoretical predictions based on laboratory measurements of the BPM pickup and the form of the resonant cavity modes as determined by numerical simulation. Lastly, the BPM was calibrated so that the beam position jitter at the BPM location could be measured. It is expected that the beam jitter scales linearly with the beam size and so the results are compared to predicted values for the latter.« less

Long bunch trains measured using a prototype cavity beam position monitor for the Compact Linear Collider

NASA Astrophysics Data System (ADS)

Cullinan, F. J.; Boogert, S. T.; Farabolini, W.; Lefevre, T.; Lunin, A.; Lyapin, A.; Søby, L.; Towler, J.; Wendt, M.

2015-11-01

The Compact Linear Collider (CLIC) requires beam position monitors (BPMs) with 50 nm spatial resolution for alignment of the beam line elements in the main linac and beam delivery system. Furthermore, the BPMs must be able to make multiple independent measurements within a single 156 ns long bunch train. A prototype cavity BPM for CLIC has been manufactured and tested on the probe beam line at the 3rd CLIC Test Facility (CTF3) at CERN. The transverse beam position is determined from the electromagnetic resonant modes excited by the beam in the two cavities of the pickup, the position cavity and the reference cavity. The mode that is measured in each cavity resonates at 15 GHz and has a loaded quality factor that is below 200. Analytical expressions for the amplitude, phase and total energy of signals from long trains of bunches have been derived and the main conclusions are discussed. The results of the beam tests are presented. The variable gain of the receiver electronics has been characterized using beam excited signals and the form of the signals for different beam pulse lengths with the 2 /3 ns bunch spacing has been observed. The sensitivity of the reference cavity signal to charge and the horizontal position signal to beam offset have been measured and are compared with theoretical predictions based on laboratory measurements of the BPM pickup and the form of the resonant cavity modes as determined by numerical simulation. Finally, the BPM was calibrated so that the beam position jitter at the BPM location could be measured. It is expected that the beam jitter scales linearly with the beam size and so the results are compared to predicted values for the latter.

The Storage Ring Proton EDM Experiment

NASA Astrophysics Data System (ADS)

Semertzidis, Yannis; Storage Ring Proton EDM Collaboration

2014-09-01

The storage ring pEDM experiment utilizes an all-electric storage ring to store ~1011 longitudinally polarized protons simultaneously in clock-wise and counter-clock-wise directions for 103 seconds. The radial E-field acts on the proton EDM for the duration of the storage time to precess its spin in the vertical plane. The ring lattice is optimized to reduce intra-beam scattering, increase the statistical sensitivity and reduce the systematic errors of the method. The main systematic error is a net radial B-field integrated around the ring causing an EDM-like vertical spin precession. The counter-rotating beams sense this integrated field and are vertically shifted by an amount, which depends on the strength of the vertical focusing in the ring, thus creating a radial B-field. Modulating the vertical focusing at 10 kHz makes possible the detection of this radial B-field by a SQUID-magnetometer (SQUID-based BPM). For a total number of n SQUID-based BPMs distributed around the ring the effectiveness of the method is limited to the N = n /2 harmonic of the background radial B-field due to the Nyquist sampling theorem limit. This limitation establishes the requirement to reduce the maximum radial B-field to 0.1-1 nT everywhere around the ring by layers of mu-metal and aluminum vacuum tube. The metho's sensitivity is 10-29 e .cm , more than three orders of magnitude better than the present neutron EDM experimental limit, making it sensitive to SUSY-like new physics mass scale up to 300 TeV.

Single-lobed frequency-dependent beam shape in an echolocating false killer whale (Pseudorca crassidens).

PubMed

Kloepper, Laura N; Nachtigall, Paul E; Quintos, Christopher; Vlachos, Stephanie A

2012-01-01

Recent studies indicate some odontocetes may produce echolocation beams with a dual-lobed vertical structure. The shape of the odontocete echolocation beam was further investigated in a false killer whale performing an echolocation discrimination task. Clicks were recorded with an array of 16 hydrophones and frequency-dependent amplitude plots were constructed to assess beam shape. The majority of the echolocation clicks were single-lobed in structure with most energy located between 20 and 80 kHz. These data indicate the false killer whale does not produce a dual-lobed structure, as has been shown in bottlenose dolphins, which may be a function of lowered frequencies in the emitted signal due to hearing loss. © 2012 Acoustical Society of America.

Display system employing acousto-optic tunable filter

NASA Technical Reports Server (NTRS)

Lambert, James L. (Inventor)

1995-01-01

An acousto-optic tunable filter (AOTF) is employed to generate a display by driving the AOTF with a RF electrical signal comprising modulated red, green, and blue video scan line signals and scanning the AOTF with a linearly polarized, pulsed light beam, resulting in encoding of color video columns (scan lines) of an input video image into vertical columns of the AOTF output beam. The AOTF is illuminated periodically as each acoustically-encoded scan line fills the cell aperture of the AOTF. A polarizing beam splitter removes the unused first order beam component of the AOTF output and, if desired, overlays a real world scene on the output plane. Resolutions as high as 30,000 lines are possible, providing holographic display capability.

Display system employing acousto-optic tunable filter

NASA Technical Reports Server (NTRS)

Lambert, James L. (Inventor)

1993-01-01

An acousto-optic tunable filter (AOTF) is employed to generate a display by driving the AOTF with a RF electrical signal comprising modulated red, green, and blue video scan line signals and scanning the AOTF with a linearly polarized, pulsed light beam, resulting in encoding of color video columns (scan lines) of an input video image into vertical columns of the AOTF output beam. The AOTF is illuminated periodically as each acoustically-encoded scan line fills the cell aperture of the AOTF. A polarizing beam splitter removes the unused first order beam component of the AOTF output and, if desired, overlays a real world scene on the output plane. Resolutions as high as 30,000 lines are possible, providing holographic display capability.

On Interactions of Oscillation Modes for a Weakly Non-Linear Undamped Elastic Beam with AN External Force

NASA Astrophysics Data System (ADS)

BOERTJENS, G. J.; VAN HORSSEN, W. T.

2000-08-01

In this paper an initial-boundary value problem for the vertical displacement of a weakly non-linear elastic beam with an harmonic excitation in the horizontal direction at the ends of the beam is studied. The initial-boundary value problem can be regarded as a simple model describing oscillations of flexible structures like suspension bridges or iced overhead transmission lines. Using a two-time-scales perturbation method an approximation of the solution of the initial-boundary value problem is constructed. Interactions between different oscillation modes of the beam are studied. It is shown that for certain external excitations, depending on the phase of an oscillation mode, the amplitude of specific oscillation modes changes.

Narrow linewidth operation of a spectral beam combined diode laser bar.

PubMed

Zhu, Zhanda; Jiang, Menghua; Cheng, Siqi; Hui, Yongling; Lei, Hong; Li, Qiang

2016-04-20

Our experiment is expected to provide an approach for realizing ultranarrow linewidth for a spectral beam combined diode laser bar. The beams of a diode laser bar are combined in a fast axis after a beam transformation system. With the help of relay optics and a transform lens with a long focal length of 1.5 m, the whole wavelength of a spectral combined laser bar can be narrowed down to 0.48 nm from more than 10 nm. We have achieved 56.7 W cw from a 19-element single bar with an M² of 1.4  (in horizontal direction)×11.6  (in vertical direction). These parameters are good evidence that all the beams from the diode laser bar are combined together to increase the brightness.

Simulations to study the static polarization limit for RHIC lattice

NASA Astrophysics Data System (ADS)

Duan, Zhe; Qin, Qing

2016-01-01

A study of spin dynamics based on simulations with the Polymorphic Tracking Code (PTC) is reported, exploring the dependence of the static polarization limit on various beam parameters and lattice settings for a practical RHIC lattice. It is shown that the behavior of the static polarization limit is dominantly affected by the vertical motion, while the effect of beam-beam interaction is small. In addition, the “nonresonant beam polarization” observed and studied in the lattice-independent model is also observed in this lattice-dependent model. Therefore, this simulation study gives insights of polarization evolution at fixed beam energies, that are not available in simple spin tracking. Supported by the U.S. Department of Energy (DE-AC02-98CH10886), Hundred-Talent Program (Chinese Academy of Sciences), and National Natural Science Foundation of China (11105164)

Resonant beam behavior studies in the Proton Storage Ring

NASA Astrophysics Data System (ADS)

Cousineau, S.; Holmes, J.; Galambos, J.; Fedotov, A.; Wei, J.; Macek, R.

2003-07-01

We present studies of space-charge-induced beam profile broadening at high intensities in the Proton Storage Ring (PSR) at Los Alamos National Laboratory. We investigate the profile broadening through detailed particle-in-cell simulations of several experiments and obtain results in good agreement with the measurements. We interpret these results within the framework of coherent resonance theory. With increasing intensity, our simulations show strong evidence for the presence of a quadrupole-mode resonance of the beam envelope with the lattice in the vertical plane. Specifically, we observe incoherent tunes crossing integer values, and large amplitude, nearly periodic envelope oscillations. At the highest operating intensities, we observe a continuing relaxation of the beam through space charge forces leading to emittance growth. The increase of emittance commences when the beam parameters encounter an envelope stop band. Once the stop band is reached, the emittance growth balances the intensity increase to maintain the beam near the stop band edge. Additionally, we investigate the potential benefit of a stop band correction to the high intensity PSR beam.

The development of W-PBPM at diagnostic beamline

NASA Astrophysics Data System (ADS)

Kim, Seungnam; Kim, Myeongjin; Kim, Seonghan; Shin, Hocheol; Kim, Jiwha; Lee, Chaesun

2017-12-01

The photon beam position monitor (PBPM) plays a critically important role in the accurate monitoring of the beam position. W (Wire)-PBPMs are installed at the front end and photon transfer line (PTL) of the diagnostic beamline and detect the change of position and angle of the beam orbit applied to the beamline. It provides beam stability and position data in real time, which can be used in feedback system with BPM in storage-ring. Also it provides beam profile, which makes it possible to figure out the specifications of beam. With two W-PBPMs, the angle information of beam could be acquired and the results coupled with beam profile are used with orbit correction. The W-PBPM has been designed and installed in the diagnostic beamline at Pohang Light Source. Herein the details of the design, analysis and performance for the W-PBPM will be reported.

Comparison of Dental Panoramic Radiography and CBCT for Measuring Vertical Bone Height in Different Horizontal Locations of Posterior Mandibular Alveolar Process.

PubMed

Shahidi, Shoaleh; Zamiri, Barbad; Abolvardi, Masoud; Akhlaghian, Marzieh; Paknahad, Maryam

2018-06-01

Accurate measurement of the available bone height is an essential step in the pre-surgical phase of dental implantation. Panoramic radiography is a unique technique in the pre-surgical phase of dental implantations because of its low cost, relatively low-dose, and availability. This article aimed to assess the reliability of dental panoramic radiographs in the accurate measurement of the vertical bone height with respect to the horizontal location of the alveolar crest. 132 cone-beam computed tomography (CBCT) of the edentulous mandibular molar area and dental panoramic radiograph of 508 patients were selected. Exclusion criteria were bone abnormalities and detectable ideal information on each modality. The alveolar ridge morphology was categorized into 7 types according to the relative horizontal location of the alveolar crest to the mandibular canal based on CBCT findings. The available bone height (ABH) was defined as the distance between the upper border of the mandibular canal and alveolar crest. One oral radiologist and one oral surgeon measured the available bone height twice on each modality with a 7-dayinterval. We found a significant correlation between dental panoramic radiographs and cone-beam computed tomography values (ICC=0.992, p < 0.001). A positive correlation between the horizontal distance of the alveolar crest to the mandibular canal and measured differences between two radiographic modalities had been found (r=0.755, p < 0.001). For each single unit of increase in the horizontal distance of the alveolar crest to the mandibular canal, dental panoramic radiographs showed 0.87 unit of overestimation ( p < 0.001). Dental panoramic radiographs can be employed safely in the pre-surgical phase of dental implantation in posterior alveolus of mandible, especially in routine and simple cases.

Measuring water level in rivers and lakes from lightweight Unmanned Aerial Vehicles

NASA Astrophysics Data System (ADS)

Bandini, Filippo; Jakobsen, Jakob; Olesen, Daniel; Reyna-Gutierrez, Jose Antonio; Bauer-Gottwein, Peter

2017-05-01

The assessment of hydrologic dynamics in rivers, lakes, reservoirs and wetlands requires measurements of water level, its temporal and spatial derivatives, and the extent and dynamics of open water surfaces. Motivated by the declining number of ground-based measurement stations, research efforts have been devoted to the retrieval of these hydraulic properties from spaceborne platforms in the past few decades. However, due to coarse spatial and temporal resolutions, spaceborne missions have several limitations when assessing the water level of terrestrial surface water bodies and determining complex water dynamics. Unmanned Aerial Vehicles (UAVs) can fill the gap between spaceborne and ground-based observations, and provide high spatial resolution and dense temporal coverage data, in quick turn-around time, using flexible payload design. This study focused on categorizing and testing sensors, which comply with the weight constraint of small UAVs (around 1.5 kg), capable of measuring the range to water surface. Subtracting the measured range from the vertical position retrieved by the onboard Global Navigation Satellite System (GNSS) receiver, we can determine the water level (orthometric height). Three different ranging payloads, which consisted of a radar, a sonar and an in-house developed camera-based laser distance sensor (CLDS), have been evaluated in terms of accuracy, precision, maximum ranging distance and beam divergence. After numerous flights, the relative accuracy of the overall system was estimated. A ranging accuracy better than 0.5% of the range and a maximum ranging distance of 60 m were achieved with the radar. The CLDS showed the lowest beam divergence, which is required to avoid contamination of the signal from interfering surroundings for narrow fields of view. With the GNSS system delivering a relative vertical accuracy better than 3-5 cm, water level can be retrieved with an overall accuracy better than 5-7 cm.

Circularly polarized light to study linear magneto-optics for ferrofluids: θ-scan technique

NASA Astrophysics Data System (ADS)

Meng, Xiangshen; Huang, Yan; He, Zhenghong; Lin, Yueqiang; Liu, Xiaodong; Li, Decai; Li, Jian; Qiu, Xiaoyan

2018-06-01

Circularly polarized light can be divided into two vertically linearly polarized light beams with  ±π/2 phase differences. In the presence of an external magnetic field, when circularly polarized light travels through a ferrofluid film, whose thickness is no more than that of λ/4 plate, magneto-optical, magnetic birefringence and dichroism effects cause the transmitted light to behave as elliptically polarized light. Using angular scan by a continuously rotating polarizer as analyzer, the angular (θ) distribution curve of relative intensity (T) corresponding to elliptically polarized light can be measured. From the T  ‑  θ curve having ellipsometry, the parameters such as the ratio of short to long axis, and angular orientation of the long axis to the vertical field direction can be obtained. Thus, magnetic birefringence and dichroism can be probed simultaneously by measuring magneto-optical, positive or negative birefringence and dichroism features from the transmission mode. The proposed method is called θ-scan technique, and can accurately determine sample stability, magnetic field direction, and cancel intrinsic light source ellipticity. This study may be helpful to further research done to ferrofluids and other similar colloidal samples with anisotropic optics.

Beam Position and Phase Monitor - Wire Mapping System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watkins, Heath A; Shurter, Robert B.; Gilpatrick, John D.

2012-04-10

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

Laser application to measure vertical sea temperature and turbidity, design phase

NASA Technical Reports Server (NTRS)

Hirschberg, J. G.; Wouters, A. W.; Simon, K. M.; Byrne, J. D.; Deverdun, C. E.

1976-01-01

An experiment to test a new method was designed, using backscattered radiation from a laser beam to measure oceanographic parameters in a fraction of a second. Tyndall, Rayleigh, Brillouin, and Raman scattering all are utilized to evaluate the parameters. A beam from a continuous argon ion laser is used together with an interferometer and interference filters to gather the information. The results are checked by direct measurements. Future shipboard and airborne experiments are described.

Processing digital images and calculation of beam emittance (pepper-pot method for the Krion source)

NASA Astrophysics Data System (ADS)

Alexandrov, V. S.; Donets, E. E.; Nyukhalova, E. V.; Kaminsky, A. K.; Sedykh, S. N.; Tuzikov, A. V.; Philippov, A. V.

2016-12-01

Programs for the pre-processing of photographs of beam images on the mask based on Wolfram Mathematica and Origin software are described. Angles of rotation around the axis and in the vertical plane are taken into account in the generation of the file with image coordinates. Results of the emittance calculation by the Pep_emit program written in Visual Basic using the generated file in the test mode are presented.

Vertical electrostatic actuator with extended digital range via tailored topology

NASA Astrophysics Data System (ADS)

Zhang, Yanhang; Dunn, Martin L.

2002-07-01

We describe the design, fabrication, and testing of an electrostatic vertical actuator that exhibits a range of motion that covers the entire initial gap between the actuator and substrate and provides controllable digital output motion. This is obtained by spatially tailoring the electrode arrangement and the stiffness characteristics of the microstructure to control the voltage-deflection characteristics. The concept is based on the electrostatic pull down of bimaterial beams, via a series of electrodes attached to the beams by flexures with tailored stiffness characteristics. The range of travel of the actuator is defined by the post-release deformed shape of the bilayer beams, and can be controlled by a post-release heat-treat process combined with a tailored actuator topology (material distribution and geometry, including spatial geometrical patterning of the individual layers of the bilayer beams). Not only does this allow an increase in the range of travel to cover the entire initial gap, but it also permits digital control of the tip of the actuator which can be designed to yield linear displacement - pull in step characteristics. We fabricated these actuators using the MUMPs surface micromachining process, and packaged them in-house. We measured, using an interferometric microscope, full field deformed shapes of the actuator at each pull in step. The measurements compare well with companion simulation results, both qualitatively and quantitatively.

High-repetition-rate, narrow-band dye lasers with water as a solvent for dyes

NASA Astrophysics Data System (ADS)

Ray, Alok K.; Sinha, Sucharita; Kundu, Soumitra; Kumar, Sasi; Nair, Sivagiriyal Karunakaran Sreenivasan; Pal, Tamal; Dasgupta, Kamalesh

2002-03-01

The performance of a copper vapor laser-pumped narrow-band dye laser in oscillator-amplifier configuration with water-based binary mixture solvents is described. Although oscillator efficiency in water-surfactant (sodium lauryl sulfate) solvent was comparable with that that employed pure ethanolic solvent, amplifier efficiency was found to be lower. Experiments that were carried out with vertically polarized pump beams and either horizontally or vertically polarized signal beams show that, in case of both the pump and signal having orthogonal polarization (horizontal) and same polarization (vertical), the extraction efficiency for both ethanolic and water-micelle media increased substantially from 15.7% to 18.5% and from 10% to 12.5%, respectively. However, the relative difference remained nearly the same, indicating that a slower orientational diffusion of excited dye molecules in a micellar medium is not responsible for a decrease in amplifier efficiency. Amplifier efficiency comparable with that containing ethanolic dye solutions could be obtained with a binary solvent that comprises a mixture of water and about 30% n-propanol. The performances of two efficient dyes, Rhodamine-6G and Kiton Red S, using water-based solvents were studied.

Cylindrical surface profile and diameter measuring tool and method

NASA Technical Reports Server (NTRS)

Currie, James R. (Inventor); Kissel, Ralph R. (Inventor); Oliver, Charles E. (Inventor); Smith, Earnest C. (Inventor); Redmon, John W. (Inventor); Wallace, Charles C. (Inventor); Swanson, Charles P. (Inventor)

1989-01-01

A tool is shown having a cross beam assembly (15) made of beams (18, 19, 20, 21) joined by a center box structure (23). The assembly (15) is adapted to be mounted by brackets (16) to the outer end of a cylindrical case (11). The center box structure (23) has a vertical shaft (25) rotatably mounted therein and extending beneath the assembly (15). Secured to the vertical shaft (25) is a radius arm (28) which is adapted to rotate with shaft (25). On the longer end of the radius arm (28) is a measuring tip (30) which contacts the cylindrical surface to be measured and which provides an electric signal representing the radius of the cylindrical surface from the center of rotation of the radius arm (28). An electric servomotor (49) rotates the vertical shaft (25) and an electronic resolver (61) provides an electric signal representing the angle of rotation of the shaft (25). The electric signals are provided to a computer station (73) which has software for its computer to calculate and print out the continuous circumference profile of the cylindrical surface, and give its true diameter and the deviations from the ideal circle.

Invited Article: Refined analysis of synchrotron radiation for NIST's SURF III facility

NASA Astrophysics Data System (ADS)

Shirley, Eric L.; Furst, Mitchell; Arp, Uwe

2018-04-01

We have developed a new method for the exact calculation of synchrotron radiation for the National Institute of Standards and Technology Synchrotron Ultraviolet Radiation Facility, SURF III. Instead of using the Schwinger formula, which is only an approximation, we develop formulae based on Graf's addition theorem for Bessel functions and accurate asymptotic expansions for Hankel functions and Bessel functions. By measuring the radiation intensity profile at two distances from the storage ring, we also confirm an apparent vertical emittance that is consistent with the vertical betatron oscillations that are intentionally introduced to extend beam lifetime by spreading the electron beam spatially. Finally, we determine how much diffraction by beamline apertures enhances the spectral irradiance at an integrating sphere entrance port at the end station. This should eliminate small but treatable components of the uncertainty budget that one should consider when using SURF III or similar synchrotrons as standard, calculable sources of ultraviolet and other radiation.

Precise Control of Vertical-Cavity Surface-Emitting Laser Structural Growth Using Molecular Beam Epitaxy In Situ Reflectance Monitor

NASA Astrophysics Data System (ADS)

Mizutani, Mitsuhiro; Teramae, Fumiharu; Takeuchi, Kazutaka; Murase, Tatsunori; Naritsuka, Shigeya; Maruyama, Takahiro

2006-04-01

A vertical-cavity surface-emitting laser (VCSEL) was fabricated using a in situ reflectance monitor by molecular beam epitaxy (MBE). Both the center wavelength of the stop band of the distributed Bragg reflector (DBR) and the resonant wavelength of the optical cavity were successfully controlled using the monitor. However, these wavelengths shifted with decreasing substrate temperature after the growth, which could be reasonably explained by the temperature dependence of refractive index. Therefore, it is necessary to set a target wavelength at a growth temperature, considering the change. The desirable laser performance of the VCSEL fabricated from the wafer indicates marked increases in the controllability and reproducibility of growth with the aid of the in situ reflectance monitor. Since it can directly measure the optical properties of the grown layers, the reflectance monitor greatly helps in the fabrication of a structure with the designed optical performance.

Beam position reconstruction for the g2p experiment in Hall A at Jefferson Lab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Pengjia; Allada, Kalyan; Allison, Trent

2015-11-03

Beam-line equipment was upgraded for experiment E08-027 (g2p) in Hall A at Jefferson Lab. Two beam position monitors (BPMs) were necessary to measure the beam position and angle at the target. A new BPM receiver was designed and built to handle the low beam currents (50-100 nA) used for this experiment. Two new super-harps were installed for calibrating the BPMs. In addition to the existing fast raster system, a slow raster system was installed. We found that before and during the experiment, these new devices were tested and debugged, and their performance was also evaluated. In order to achieve themore » required accuracy (1-2 mm in position and 1-2 mrad in angle at the target location), the data of the BPMs and harps were carefully analyzed, as well as reconstructing the beam position and angle event by event at the target location. Finally, the calculated beam position will be used in the data analysis to accurately determine the kinematics for each event.« less

Aliasing errors in measurements of beam position and ellipticity

NASA Astrophysics Data System (ADS)

Ekdahl, Carl

2005-09-01

Beam position monitors (BPMs) are used in accelerators and ion experiments to measure currents, position, and azimuthal asymmetry. These usually consist of discrete arrays of electromagnetic field detectors, with detectors located at several equally spaced azimuthal positions at the beam tube wall. The discrete nature of these arrays introduces systematic errors into the data, independent of uncertainties resulting from signal noise, lack of recording dynamic range, etc. Computer simulations were used to understand and quantify these aliasing errors. If required, aliasing errors can be significantly reduced by employing more than the usual four detectors in the BPMs. These simulations show that the error in measurements of the centroid position of a large beam is indistinguishable from the error in the position of a filament. The simulations also show that aliasing errors in the measurement of beam ellipticity are very large unless the beam is accurately centered. The simulations were used to quantify the aliasing errors in beam parameter measurements during early experiments on the DARHT-II accelerator, demonstrating that they affected the measurements only slightly, if at all.

Development of the PEFP's beam line BPM

NASA Astrophysics Data System (ADS)

Ryu, Jin-Yeong; Kwon, Hyeok-Jung; Jang, Ji-Ho; Kim, Han-Sung; Seol, Kyung-Tae; Cho, Yong-Sub

2013-01-01

The Proton Engineering Frontier Project (PEFP) has 20-MeV and 100-MeV beam lines to supply proton beams to users. A stripline-type Beam Position Monitor (BPM) was designed and fabricated in order to measure the beam's position in the beam line. The RF properties of the BPM were measured and compared with the simulation. After the sensitivity of the BPM at a test stand had been obtained, we performed a beam test in a test beam line of the PEFP 20-MeV proton linac.

Comparison of electron-beam and ungated helical CT in detecting coronary arterial calcification by using a working heart phantom and artificial coronary arteries.

PubMed

Hopper, Kenneth D; Strollo, Diane C; Mauger, David T

2002-02-01

To determine the sensitivity and specificity of cardiac gated electron-beam computed tomography (CT) and ungated helical CT in detecting and quantifying coronary arterial calcification (CAC) by using a working heart phantom and artificial coronary arteries. A working heart phantom simulating normal cardiac motion and providing attenuation equal to that of an adult thorax was used. Thirty tubes with a 3-mm inner diameter were internally coated with pulverized human cortical bone mixed with epoxy glue to simulate minimal (n = 10), mild (n = 10), or severe (n = 10) calcified plaques. Ten additional tubes were not coated and served as normal controls. The tubes were attached to the same location on the phantom heart and scanned with electron-beam CT and helical CT in horizontal and vertical planes. Actual plaque calcium content was subsequently quantified with atopic spectroscopy. Two blinded experienced radiologic imaging teams, one for each CT system, separately measured calcium content in the model vessels by using a Hounsfield unit threshold of 130 or greater. The sensitivity and specificity of electron-beam CT in detecting CAC were 66.1% and 80.0%, respectively. The sensitivity and specificity of helical CT were 96.4% and 95.0%, respectively. Electron-beam CT was less reliable when vessels were oriented vertically (sensitivity and specificity, 71.4% and 70%; 95% CI: 39.0%, 75.0%) versus horizontally (sensitivity and specificity, 60.7% and 90.0%; 95% CI: 48.0%, 82.0%). When a correction factor was applied, the volume of calcified plaque was statistically better quantified with helical CT than with electron-beam CT (P =.004). Ungated helical CT depicts coronary arterial calcium better than does gated electron-beam CT. When appropriate correction factors are applied, helical CT is superior to electron-beam CT in quantifying coronary arterial calcium. Although further work must be done to optimize helical CT grading systems and scanning protocols, the data of this study demonstrated helical CT's inherent advantage over currently commercially available electron-beam CT systems in CAC detection and quantification.

Design, test, and calibration of an electrostatic beam position monitor

NASA Astrophysics Data System (ADS)

Cohen-Solal, Maurice

2010-03-01

The low beta of proton or ion beams favors an electrostatic pickup to measure the transverse beam centroid position. Often papers on beam position monitors (BPM) are focused on a particular aspect of the problem; however, it is important to consider all various issues of a position measurement system. Based on our experience at the IPHI (high intensity injector proton) facility at CEA-Saclay, this paper will address all aspects to design, test, and calibrate a BPM for proton linear accelerators, while emphasizing the determination of the absolute beam position. We present details of the readout electronics, and describe the calibration of the BPM using a test station. For calculation and simulation of the electrical signals we developed a Mathematica script. The error analysis presented, on the basis of six BPMs installed in the high energy section of IPHI, demonstrates the expected accuracy of the position measurement. These studies also identify the parameters that could improve the performance of the beam position control. The experience from these developments is currently being used for the BPM design and test stand dedicated to the Spiral2 accelerator at Ganil-Caen which will deliver heavy ion beams.

Development of high resolution linear-cut beam position monitor for heavy-ion synchrotron of KHIMA project

NASA Astrophysics Data System (ADS)

Hwang, Ji-Gwang; Yang, Tae-Keun; Forck, Peter; Noh, Seon Yeong; Hahn, Garam; Choi, Minkyoo

2017-04-01

A beam position monitor with high precision and resolution is required to control the beam trajectory for matching to the injection orbit and acceleration in a heavy-ion synchrotron. It will be also used for measuring the beta function, tune, and chromaticity. Since the bunch length at heavy ion synchrotron is relatively long, a few meters, a boxlike device with plates of typically 20 cm length is used to enhance the signal strength and to get a precise linear dependence with respect to the beam displacement. Especially, the linear-cut beam position monitor is adopted to satisfy the position resolution of 100 μm and accuracy of 200 μm for a nominal beam intensity in the KHIMA synchrotron of ∼ 7 ×108 particles for the carbon beams and ∼ 2 ×1010 for the proton beams. In this paper, we show the electromagnetic design of the electrode and surroundings to satisfy the resolution of 100 μm, the criteria for mechanical aspect to satisfy the position accuracy of 200 μm, the measurement results by using wire test-bench, design and measurement of a high input impedance pre-amplifier, and the beam-test results with long (∼1.6 μs) electron beam in Pohang accelerator laboratory (PAL).

An automatic alignment system for measuring optical path of transmissometer based on light beam scanning

NASA Astrophysics Data System (ADS)

Zhou, Shudao; Ma, Zhongliang; Wang, Min; Peng, Shuling

2018-05-01

This paper proposes a novel alignment system based on the measurement of optical path using a light beam scanning mode in a transmissometer. The system controls both the probe beam and the receiving field of view while scanning in two vertical directions. The system then calculates the azimuth angle of the transmitter and the receiver to determine the precise alignment of the optical path. Experiments show that this method can determine the alignment angles in less than 10 min with errors smaller than 66 μrad in the azimuth. This system also features high collimation precision, process automation and simple installation.

Focusing metasurface quantum-cascade laser with a near diffraction-limited beam

DOE PAGES

Xu, Luyao; Chen, Daguan; Itoh, Tatsuo; ...

2016-10-17

A terahertz vertical-external-cavity surface-emitting-laser (VECSEL) is demonstrated using an active focusing reflectarray metasurface based on quantum-cascade gain material. The focusing effect enables a hemispherical cavity with flat optics, which exhibits higher geometric stability than a plano-plano cavity and a directive and circular near-diffraction limited Gaussian beam with M 2 beam parameter as low as 1.3 and brightness of 1.86 × 10 6 Wsr –1m –2. As a result, this work initiates the potential of leveraging inhomogeneous metasurface and reflectarray designs to achieve high-power and high-brightness terahertz quantum-cascade VECSELs.

Experimental study of geotextile as plinth beam in a pile group-supported modeled building frame

NASA Astrophysics Data System (ADS)

Ravi Kumar Reddy, C.; Gunneswara Rao, T. D.

2017-12-01

This paper presents the experimental results of static vertical load tests on a model building frame with geotextile as plinth beam supported by pile groups embedded in cohesionless soil (sand). The experimental results have been compared with those obtained from the nonlinear FEA and conventional method of analysis. The results revealed that the conventional method of analysis gives a shear force of about 53%, bending moment at the top of the column about 17% and at the base of the column about 50-98% higher than that by the nonlinear FEA for the frame with geotextile as plinth beam.

Electron beam welding passes initial test

DOE Office of Scientific and Technical Information (OSTI.GOV)

de Sirvy, B.

1979-11-01

Once the new electron-beam welding process is coupled with vertical or J-curve pipelaying techniques, Total-Compagnie Francaise des Petroles (Gestion and Recherches) will be able to offer a system capable of laying up to 36-in. pipe in deep water (1000-9900 ft) at a pace competitive with the best performance of a shallow-water barge: 8200 ft in 24 hr. Electron-beam welding provides the fast, single-station joining needed to make J-curve laying economical. Tests recently demonstrated that this welding technique can join 1.25-in.-wall, 24-in. pipe in less than 3 min; conventional processes require 1-1 1/2 hr.

An experimental technique to repair cracked teeth using calcium phosphate, melted by a laser beam: an in vitro evaluation.

PubMed

Levy, G C; Koubi, G F

1993-11-01

Using a neodymium: yttrium-aluminum-garnet laser beam to seal vertical root fracture lines with tricalcium phosphate paste represents an alternative treatment for cracked teeth with noted clinical results. This article describes a study of the permeability of molten crystals of hydroxyapatite in the dentin of a cracked root after crack lines have been filled with a preparation of tricalcium phosphate melted by a neodymium: yttrium-aluminum-garnet laser beam. The morphology of the sealed cracks was analyzed under a scanning electron microscope that showed a deep fusion of tricalcium phosphate along crack lines.

Local fluctuations of ozone from 16 km to 45 km deduced from in situ vertical ozone profile

NASA Technical Reports Server (NTRS)

Moreau, G.; Robert, C.

1994-01-01

A vertical ozone profile obtained by an in situ ozone sonde from 16 km to 45 km, has allowed to observe local ozone concentration variations. These variations can be observed, thanks to a fast measurement system based on a UV absorption KrF excimer laser beam in a multipass cell. Ozone standard deviation versus altitude calculated from the mean is derived. Ozone variations or fluctuations are correlated with the different dynamic zones of the stratosphere.

Room-temperature lasing operation of a quantum-dot vertical-cavity surface-emitting laser

NASA Astrophysics Data System (ADS)

Saito, Hideaki; Nishi, Kenichi; Ogura, Ichiro; Sugou, Shigeo; Sugimoto, Yoshimasa

1996-11-01

Self-assembled growth of quantum dots by molecular-beam epitaxy is used to form the active region of a vertical-cavity surface-emitting laser (VCSEL). Ten layers of InGaAs quantum dots are stacked in order to increase the gain. This quantum-dot VCSEL has a continuous-wave operating current of 32 mA at room temperature. Emission spectra at various current injections demonstrate that the lasing action is associated with a higher-order transition in the quantum dots.

Angle performance on optima MDxt

DOE Office of Scientific and Technical Information (OSTI.GOV)

David, Jonathan; Kamenitsa, Dennis

2012-11-06

Angle control on medium current implanters is important due to the high angle-sensitivity of typical medium current implants, such as halo implants. On the Optima MDxt, beam-to-wafer angles are controlled in both the horizontal and vertical directions. In the horizontal direction, the beam angle is measured through six narrow slits, and any angle adjustment is made by electrostatically steering the beam, while cross-wafer beam parallelism is adjusted by changing the focus of the electrostatic parallelizing lens (P-lens). In the vertical direction, the beam angle is measured through a high aspect ratio mask, and any angle adjustment is made by slightlymore » tilting the wafer platen prior to implant. A variety of tests were run to measure the accuracy and repeatability of Optima MDxt's angle control. SIMS profiles of a high energy, channeling sensitive condition show both the cross-wafer angle uniformity, along with the small-angle resolution of the system. Angle repeatability was quantified by running a channeling sensitive implant as a regular monitor over a seven month period and measuring the sheet resistance-to-angle sensitivity. Even though crystal cut error was not controlled for in this case, when attributing all Rs variation to angle changes, the overall angle repeatability was measured as 0.16 Degree-Sign (1{sigma}). A separate angle repeatability test involved running a series of V-curves tests over a four month period using low crystal cut wafers selected from the same boule. The results of this test showed the angle repeatability to be <0.1 Degree-Sign (1{sigma}).« less

Autotransplantation of Mandibular Third Molar with Buccal Cortical Plate to Replace Vertically Fractured Mandibular Second Molar: A Novel Technique.

PubMed

Zufía, Juan; Abella, Francesc; Trebol, Ivan; Gómez-Meda, Ramón

2017-09-01

Tooth replacement often leads to inadequate vertical volume in the recipient site bone when a tooth has been extracted because of a vertical root fracture (VRF). This case report presents the autotransplantation of a mandibular third molar (tooth #32) with the attached buccal cortical plate to replace a mandibular second molar (tooth #31) diagnosed with a VRF. After extraction of tooth #31, the recipient socket was prepared based on the size measured in advance with cone-beam computed tomographic imaging. The precise and calculated osteotomy of the cortical bone of tooth #32 allowed for the exact placement of the donor tooth in the position of tooth #31. The total extraoral time was only 25 minutes. The block was fixed to the recipient socket with an osteosynthesis screw and splinted with a double resin wire for 8 weeks. At the 6-month follow-up, the screw was removed, and the stability of the tooth and the regeneration obtained throughout the vestibular area were confirmed. At the 2-year follow-up, the transplanted tooth was asymptomatic and maintained a normal bone level. Advantages of autotransplantation over dental implants include maintenance of proprioception, possible orthodontic movements, and a relatively low cost. This case report demonstrates that an autotransplantation of a third molar attached to its buccal cortical plate is a viable option to replace teeth with a VRF. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Measuring and forecasting great tsunamis by GNSS-based vertical positioning of multiple ships

NASA Astrophysics Data System (ADS)

Inazu, D.; Waseda, T.; Hibiya, T.; Ohta, Y.

2016-12-01

Vertical ship positioning by the Global Navigation Satellite System (GNSS) was investigated for measuring and forecasting great tsunamis. We first examined existing GNSS vertical position data of a navigating vessel. The result indicated that by using the kinematic Precise Point Positioning (PPP) method, tsunamis greater than 10^-1 m can be detected from the vertical position of the ship. Based on Automatic Identification System (AIS) data, tens of cargo ships and tankers are regularly identified navigating over the Nankai Trough, southwest of Japan. We then assumed that a future Nankai Trough great earthquake tsunami will be observed by ships at locations based on AIS data. The tsunami forecast capability by these virtual offshore tsunami measurements was examined. A conventional Green's function based inversion was used to determine the initial tsunami height distribution. Tsunami forecast tests over the Nankai Trough were carried out using simulated tsunami data of the vertical positions of multiple cargo ships/tankers on a certain day, and of the currently operating observations by deep-sea pressure gauges and Global Positioning System (GPS) buoys. The forecast capability of ship-based tsunami height measurements alone was shown to be comparable to or better than that using the existing offshore observations.

Systems and methods for detecting an image of an object using multi-beam imaging from an X-ray beam having a polychromatic distribution

DOEpatents

Parham, Christopher A; Zhong, Zhong; Pisano, Etta; Connor, Jr., Dean M

2015-03-03

Systems and methods for detecting an image of an object using a multi-beam imaging system from an x-ray beam having a polychromatic energy distribution are disclosed. According to one aspect, a method can include generating a first X-ray beam having a polychromatic energy distribution. Further, the method can include positioning a plurality of monochromator crystals in a predetermined position to directly intercept the first X-ray beam such that a plurality of second X-ray beams having predetermined energy levels are produced. Further, an object can be positioned in the path of the second X-ray beams for transmission of the second X-ray beams through the object and emission from the object as transmitted X-ray beams. The transmitted X-ray beams can each be directed at an angle of incidence upon one or more crystal analyzers. Further, an image of the object can be detected from the beams diffracted from the analyzer crystals.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rong, Y; Walston, S

Purpose: To evaluate the use of 3D optical surface imaging as a new surrogate for respiratory motion gated deep-inspiration breath-hold (DIBH) technique for left breast cancer patients. Methods: Patients with left-sided breast cancer after lumpectomy or mastectomy were selected as candidates for DIBH technique for their external beam radiation therapy. Treatment plans were created on both free breathing (FB) and DIBH CTs to determine whether DIBH was beneficial in reducing heart doses. The Real-time Position Management (RPM) system was used to acquire patient's breathing trace during DIBH CT acquisition and treatment delivery. The reference 3D surface models from FB andmore » DIBH CTs were generated and transferred to the “AlignRT” system for patient positioning and real-time treatment monitoring. MV Cine images were acquired for each beam as quality assurance for intra-fractional position verification. The chest wall excursions measured on these images were used to define the actual target position during treatment, and to investigate the accuracy and reproducibility of RPM and AlignRT. Results: Reduction in heart dose can be achieved for left-sided breast patients using DIBH. Results showed that RPM has poor correlation with target position, as determined by the MV Cine imaging. This indicates that RPM may not be an adequate surrogate in defining the breath-hold level when used alone. Alternatively, the AlignRT surface imaging demonstrated a better correlation with the actual CW excursion during DIBH. Both the vertical and magnitude real-time deltas (RTDs) reported by AlignRT can be used as the gating parameter, with a recommend threshold of ±3 mm and 5 mm, respectively. Conclusion: 3D optical surface imaging serves as a superior target surrogate for the left breast treatment when compared to RPM. Working together with the realtime MV Cine imaging, they ensure accurate patient setup and dose delivery, while minimizing the imaging dose to patients.« less

Accuracy and precision of patient positioning for pelvic MR-only radiation therapy using digitally reconstructed radiographs

NASA Astrophysics Data System (ADS)

Kemppainen, R.; Vaara, T.; Joensuu, T.; Kiljunen, T.

2018-03-01

Background and Purpose. Magnetic resonance imaging (MRI) has in recent years emerged as an imaging modality to drive precise contouring of targets and organs at risk in external beam radiation therapy. Moreover, recent advances in MRI enable treatment of cancer without computed tomography (CT) simulation. A commercially available MR-only solution, MRCAT, offers a single-modality approach that provides density information for dose calculation and generation of positioning reference images. We evaluated the accuracy of patient positioning based on MRCAT digitally reconstructed radiographs (DRRs) by comparing to standard CT based workflow. Materials and Methods. Twenty consecutive prostate cancer patients being treated with external beam radiation therapy were included in the study. DRRs were generated for each patient based on the planning CT and MRCAT. The accuracy assessment was performed by manually registering the DRR images to planar kV setup images using bony landmarks. A Bayesian linear mixed effects model was used to separate systematic and random components (inter- and intra-observer variation) in the assessment. In addition, method agreement was assessed using a Bland-Altman analysis. Results. The systematic difference between MRCAT and CT based patient positioning, averaged over the study population, were found to be (mean [95% CI])  -0.49 [-0.85 to  -0.13] mm, 0.11 [-0.33 to  +0.57] mm and  -0.05 [-0.23 to  +0.36] mm in vertical, longitudinal and lateral directions, respectively. The increases in total random uncertainty were estimated to be below 0.5 mm for all directions, when using MR-only workflow instead of CT. Conclusions. The MRCAT pseudo-CT method provides clinically acceptable accuracy and precision for patient positioning for pelvic radiation therapy based on planar DRR images. Furthermore, due to the reduction of geometric uncertainty, compared to dual-modality workflow, the approach is likely to improve the total geometric accuracy of pelvic radiation therapy.

Accuracy evaluation of the optical surface monitoring system on EDGE linear accelerator in a phantom study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mancosu, Pietro; Fogliata, Antonella, E-mail: Antonella.Fogliata@humanitas.it; Stravato, Antonella

2016-07-01

Frameless stereotactic radiosurgery (SRS) requires dedicated systems to monitor the patient position during the treatment to avoid target underdosage due to involuntary shift. The optical surface monitoring system (OSMS) is here evaluated in a phantom-based study. The new EDGE linear accelerator from Varian (Varian, Palo Alto, CA) integrates, for cranial lesions, the common cone beam computed tomography (CBCT) and kV-MV portal images to the optical surface monitoring system (OSMS), a device able to detect real-time patient's face movements in all 6 couch axes (vertical, longitudinal, lateral, rotation along the vertical axis, pitch, and roll). We have evaluated the OSMS imagingmore » capability in checking the phantoms' position and monitoring its motion. With this aim, a home-made cranial phantom was developed to evaluate the OSMS accuracy in 4 different experiments: (1) comparison with CBCT in isocenter location, (2) capability to recognize predefined shifts up to 2° or 3 cm, (3) evaluation at different couch angles, (4) ability to properly reconstruct the surface when the linac gantry visually block one of the cameras. The OSMS system showed, with a phantom, to be accurate for positioning in respect to the CBCT imaging system with differences of 0.6 ± 0.3 mm for linear vector displacement, with a maximum rotational inaccuracy of 0.3°. OSMS presented an accuracy of 0.3 mm for displacement up to 1 cm and 1°, and 0.5 mm for larger displacements. Different couch angles (45° and 90°) induced a mean vector uncertainty < 0.4 mm. Coverage of 1 camera produced an uncertainty < 0.5 mm. Translations and rotations of a phantom can be accurately detect with the optical surface detector system.« less

THE VERTICAL

NASA Technical Reports Server (NTRS)

Albert, Stephen L.; Spencer, Jeffrey B.

1994-01-01

'THE VERTICAL' computer keyboard is designed to address critical factors which contribute to Repetitive Motion Injuries (RMI) (including Carpal Tunnel Syndrome) in association with computer keyboard usage. This keyboard splits the standard QWERTY design into two halves and positions each half 90 degrees from the desk. In order to access a computer correctly. 'THE VERTICAL' requires users to position their bodies in optimal alignment with the keyboard. The orthopaedically neutral forearm position (with hands palms-in and thumbs-up) reduces nerve compression in the forearm. The vertically arranged keypad halves ameliorate onset occurrence of keyboard-associated RMI. By utilizing visually-reference mirrored mylar surfaces adjustable to the user's eye, the user is able to readily reference any key indicia (reversed) just as they would on a conventional keyboard. Transverse adjustability substantially reduces cumulative musculoskeletal discomfort in the shoulders. 'THE VERTICAL' eliminates the need for an exterior mouse by offering a convenient finger-accessible curser control while the hands remain in the vertically neutral position. The potential commercial application for 'THE VERTICAL' is enormous since the product can effect every person who uses a computer anywhere in the world. Employers and their insurance carriers are spending hundreds of millions of dollars per year as a result of RMI. This keyboard will reduce the risk.

Polarization holographic gratings in PAZO azopolymer recorded with different recording-beams polarizations

NASA Astrophysics Data System (ADS)

Mateev, G.; Nedelchev, L.; Ivanov, D.; Tomova, R.; Petrova, P.; Strijkova, V.; Berberova, N.; Nazarova, D.

2018-03-01

Polarization holographic gratings (PHG) were recorded using a laser emitting a wavelength of 491 nm in thin films of the (poly[1-[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl, sodium salt]) azopolymer, shortly denoted as PAZO. Thin azopolymer films with various thicknesses were spin-coated on plastic and glass substrates. Four different polarization states of the recording beams were used, and the results compared: a) two vertical linear polarizations, b) horizontal and vertical linear polarizations, c) linear polarizations at +45° and –45° relative to the recording plane, and d) two orthogonal circular polarizations – left- and right-handed (LCP and RCP). The diffraction efficiency in the +1 diffraction order was monitored in real time by a probing laser beam at the wavelength of 635 nm. The results indicate that the highest diffraction efficiency is achieved when recording with orthogonal polarizations – linear at ±45° or left and right circular. This is explained by the ability of the azopolymer material to record the variations in the polarization state of light better than the variations in its intensity. The holographic gratings obtained can be used to enhance the light-extraction efficiency of an OLED device.

Fabrication of ultra-high aspect ratio (>160:1) silicon nanostructures by using Au metal assisted chemical etching

NASA Astrophysics Data System (ADS)

Li, Hailiang; Ye, Tianchun; Shi, Lina; Xie, Changqing

2017-12-01

We present a facile and effective approach for fabricating high aspect ratio, dense and vertical silicon nanopillar arrays, using a combination of metal etching following electron-beam lithography and Au metal assisted chemical etching (MacEtch). Ti/Au nanostructures used as catalysts in MacEtch are formed by single layer resist-based electron-beam exposure followed by ion beam etching. The effects of MacEtch process parameters, including half period, etching time, the concentrations of H2O2 and HF, etching temperature and drying method are systematically investigated. Especially, we demonstrate an enhancement of etching quality by employing cold MacEtch process, and an enhancement in preventing the collapse of high aspect ratio nanostructures by employing low surface tension rinse liquid and natural evaporation in the drying stage. Using an optimized MacEtch process, vertical silicon nanopillar arrays with a period of 250 nm and aspect ratio up to 160:1 are realized. Our results should be instructive for exploring the achievable aspect ratio limit in silicon nanostructures and may find potential applications in photovoltaic devices, thermoelectric devices and x-ray diffractive optics.

Progress towards a cesium atomic fountain clock

NASA Astrophysics Data System (ADS)

Klipstein, William M.; Raithel, Georg A.; Rolston, Steven L.; Phillips, William D.; Ekstrom, Christopher R.

1997-04-01

We have been developing a fountain of laser--cooled cesium atoms for use as an atomic clock. Our design largely follows that of the fountain built at LPTF in Paris. In our fountain, chirp--slowed atoms are first collected in a Magneto--Optic Trap (MOT) and then cooled to a few μK in optical molasses. The cooled atoms are then launched vertically into a "moving molasses" by shifting the frequencies of the vertical cooling beams. The atoms then travel through a microwave cavity tuned to the 9.2 GHz cesium hyperfine frequency for a first Ramsey pulse. After roughly 0.5 seconds of free flight under the influence of gravity, the atoms fall back through the microwave cavity and into an optical state--detection region which detects the number of atoms making the F=3 arrow F=4 transition. The increased Ramsey interaction time improves the short--time precision as compared to traditional atomic beam experiments, while many systematic shifts which limit the accuracy of an atomic beam clock are reduced by the low atomic velocity and the retrace of the atomic trajectory through the microwave cavity. We will discuss the progress towards a working fountain being assembled in our laboratory.

Antenna induced range smearing in MST radars

NASA Technical Reports Server (NTRS)

Watkins, B. J.; Johnston, P. E.

1984-01-01

There is considerable interest in developing stratosphere troposphere (ST) and mesosphere stratosphere troposphere (MST) radars for higher resolution to study small-scale turbulent structures and waves. At present most ST and MST radars have resolutions of 150 meters or larger, and are not able to distinguish the thin (40 - 100 m) turbulent layers that are known to occur in the troposphere and stratosphere, and possibly in the mesosphere. However the antenna beam width and sidelobe level become important considerations for radars with superior height resolution. The objective of this paper is to point out that for radars with range resolutions of about 150 meters or less, there may be significant range smearing of the signals from mesospheric altitudes due to the finite beam width of the radar antenna. At both stratospheric and mesospheric heights the antenna sidelobe level for lear equally spaced phased arrays may also produce range aliased signals. To illustrate this effect the range smearing functions for two vertically directed antennas have been calculated, (1) an array of 32 coaxial-collinear strings each with 48 elements that simulates the vertical beam of the Poker Flat, Glaska, MST radar; and (2) a similar, but smaller, array of 16 coaxial-collinear strings each with 24 elements.

SU-F-T-70: A High Dose Rate Total Skin Electron Irradiation Technique with A Specific Inter-Film Variation Correction Method for Very Large Electron Beam Fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, X; Rosenfield, J; Dong, X

2016-06-15

Purpose: Rotational total skin electron irradiation (RTSEI) is used in the treatment of cutaneous T-cell lymphoma. Due to inter-film uniformity variations the dosimetry measurement of a large electron beam of a very low energy is challenging. This work provides a method to improve the accuracy of flatness and symmetry for a very large treatment field of low electron energy used in dual beam RTSEI. Methods: RTSEI is delivered by dual angles field a gantry of ±20 degrees of 270 to cover the upper and the lower halves of the patient body with acceptable beam uniformity. The field size is inmore » the order of 230cm in vertical height and 120 cm in horizontal width and beam energy is a degraded 6 MeV (6 mm of PMMA spoiler). We utilized parallel plate chambers, Gafchromic films and OSLDs as a measuring devices for absolute dose, B-Factor, stationary and rotational percent depth dose and beam uniformity. To reduce inter-film dosimetric variation we introduced a new specific correction method to analyze beam uniformity. This correction method uses some image processing techniques combining film value before and after radiation dose to compensate the inter-variation dose response differences among films. Results: Stationary and rotational depth of dose demonstrated that the Rp is 2 cm for rotational and the maximum dose is shifted toward the surface (3mm). The dosimetry for the phantom showed that dose uniformity reduced to 3.01% for the vertical flatness and 2.35% for horizontal flatness after correction thus achieving better flatness and uniformity. The absolute dose readings of calibrated films after our correction matched with the readings from OSLD. Conclusion: The proposed correction method for Gafchromic films will be a useful tool to correct inter-film dosimetric variation for the future clinical film dosimetry verification in very large fields, allowing the optimizations of other parameters.« less

SU-E-T-191: Commissioning and Dosimetric Characteristics of Elekta Agility for Total Skin Electron Beam (TSEB) Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sayler, E; Charpentier, P; Micaily, B

2015-06-15

Purpose The purpose of this work is to publish beam data from Elekta Synergy(R) linear accelerators with Agility(TM) MLC for total skin electron beam (TSEB) therapy using the HDRE1 (High Dose Rate Electron 6MeV) energy. Method & Materials The optimal gantry angles for TSEB were determined using ion chamber measurements along a vertical profile at 450cm SSD. After gantry angles were chosen, field uniformity was measured over the entire treatment area. Uniformity was measured with and without the patient support device, allowing the dosimetric effect of the support device to be determined. Beam output and PDD were measured at themore » calibration point (450cm SSD) for a dual beam using a parallel plate chamber in solid water. These measurements were repeated with the chamber and phantom rotated about the patient isocenter at various angles, in order to measure the contribution from oblique beams. This technique provides a precise measurement of the treatment skin dose (TSD). Lastly, ion chamber measurements were verified by film and diodes. Results The optimal gantry angle for 450 cm SSD was determined to be 90±16°. This achieved uniformity better than 96% on the vertical axis, and 92% along the horizontal axis. HDRE1 was calibrated to deliver 10 cGy/MU at standard geometry (100 cm SSD, 1.2 cm depth). Thus at TSEB geometry (450 cm SSD, 0.1 cm depth) the output of the AP dual field was measured to be 0.35 cGy/MU. The TSD of a 20 cm radius cylinder for six (equally, 60° spaced) dual fields was measured to be 1.19 cGy/MU. Percent Depth Dose data for the AP dual field and TSD are shown in Figure 2. Conclusion This paper provides a modern procedure for commissioning TSEB therapy on a linear accelerator, and clinical beam data for the Elekta Synergy(R) with Agility(TM) MLC.« less

Radial Internal Material Handling System (RIMS) for Circular Habitat Volumes

NASA Technical Reports Server (NTRS)

Howe, Alan S.; Haselschwardt, Sally; Bogatko, Alex; Humphrey, Brian; Patel, Amit

2013-01-01

On planetary surfaces, pressurized human habitable volumes will require a means to carry equipment around within the volume of the habitat, regardless of the partial gravity (Earth, Moon, Mars, etc.). On the NASA Habitat Demonstration Unit (HDU), a vertical cylindrical volume, it was determined that a variety of heavy items would need to be carried back and forth from deployed locations to the General Maintenance Work Station (GMWS) when in need of repair, and other equipment may need to be carried inside for repairs, such as rover parts and other external equipment. The vertical cylindrical volume of the HDU lent itself to a circular overhead track and hoist system that allows lifting of heavy objects from anywhere in the habitat to any other point in the habitat interior. In addition, the system is able to hand-off lifted items to other material handling systems through the side hatches, such as through an airlock. The overhead system consists of two concentric circle tracks that have a movable beam between them. The beam has a hoist carriage that can move back and forth on the beam. Therefore, the entire system acts like a bridge crane curved around to meet itself in a circle. The novelty of the system is in its configuration, and how it interfaces with the volume of the HDU habitat. Similar to how a bridge crane allows coverage for an entire rectangular volume, the RIMS system covers a circular volume. The RIMS system is the first generation of what may be applied to future planetary surface vertical cylinder habitats on the Moon or on Mars.

Paraxial propagation of the first-order chirped Airy vortex beams in a chiral medium.

PubMed

Xie, Jintao; Zhang, Jianbin; Ye, Junran; Liu, Haowei; Liang, Zhuoying; Long, Shangjie; Zhou, Kangzhu; Deng, Dongmei

2018-03-05

We introduce the propagation of the first-order chirped Airy vortex beams (FCAiV) in a chiral medium analytically. Results show that the FCAiV beams split into the left circularly polarized vortex (LCPV) beams and the right circularly polarized vortex (RCPV) beams, which have totally different propagation trajectories in the chiral medium. In this paper, we investigate the effects of the first-order chirped parameter β, the chiral parameter γ and the optical vortex on the propagation process of the FCAiV beams. It is shown that the propagation trajectory of the FCAiV beams declines with the chirped parameter increasing. Besides, the increase of the chiral parameter acting on the LCPV beams makes the relative position between the main lobe and the optical vortex further while the effect on the RCPV beams is the opposite. Furthermore, the relative position between the main lobe and the optical vortex contributes to the position of the intensity focusing. Meanwhile, with the chiral parameter increasing, the maximum gradient and scattering forces of the LCPV beams decrease but those of the RCPV beams will increase during the propagation. It is significant that we can control the propagation trajectory, the intensity focusing position and the radiation forces of the FCAiV beams by varying the chirped parameter and the chiral parameter.

The Effect of Pitch, Roll, and Yaw on Airborne Gravity Observations of the NOAA GRAV-D Project

NASA Astrophysics Data System (ADS)

Childers, V. A.; Kanney, J.; Youngman, M.

2017-12-01

Aircraft turbulence can wreak havoc on the gravity measurementby beam-style gravimeters. Prior studies have confirmed the correlation of poor quality airborne gravity data collection to amplified aircraft motion. Motion in the aircraft is the combined effect of the airframe design, the autopilot and its performance, and the weather/wind regime. NOAA's National Geodetic Survey has launched the Gravity for the Redefinition of the American Vertical Datum project (GRAV-D) to provide the foundation for a new national vertical datum by 2022. This project requires collecting airborne gravity data covering the entire country and its holdings. The motion of the aircraft employed in this project is of prime importance because we use a beam-style gravimeter mounted on a gyro-stabilized platform to align the sensor to a time-averaged local vertical. Aircraft turbulence will tend to drive the platform off-level, allowing horizontal forces to map into the vertical gravity measurement. Recently, the GRAV-D project has experimented with two new factors in airborne gravity data collection. The first aspect is the use of the Aurora optionally piloted Centaur aircraft. This aircraft can be flown either with or without a pilot, but the autopilot is specifically designed to be very accurate. Incorporated into the much smaller frame of this aircraft is a new gravimeter developed by Micro-g LaCoste, called the Turnkey Airborne Gravimeter System 7 (TAGS7). This smaller, lighter instrument also has a new design whereby the beam is held fixed in an electromagnetic force field. The result of this new configuration is notably improved data quality in wind conditions higher than can be tolerated by our current system. So, which caused the improvement, the aircraft motion or the new meter? This study will start to tease apart these two effects with recently collected survey data. Specifically, we will compare the motion profile of the Centaur aircraft with other aircraft in the GRAV-D portfolio that we use successfully. In addition, we will investigate the relationship of aircraft motion, as measured by pitch, roll, and yaw, to airborne gravity quality in the Centaur operation as well as measurement aboard other aircraft with the beam-style sensor.

Second harmonic generation of off axial vortex beam in the case of walk-off effect

NASA Astrophysics Data System (ADS)

Chen, Shunyi; Ding, Panfeng; Pu, Jixiong

2016-07-01

Process of off axial vortex beam propagating in negative uniaxial crystal is investigated in this work. Firstly, we get the formulae of the normalized electric field and calculate the location of vortices for second harmonic beam in two type of phase matching. Then, numerical analysis verifies that the intensity distribution and location of vortices of the first order original vortex beam depend on the walk-off angle and off axial magnitude. It is shown that, in type I phase matching, the distribution of vortices is symmetrical about the horizontal axis, the separation distance increases as the off axial magnitude increases or the off axial magnitude deceases. However, in type II phase matching, the vortices are symmetrical along with some vertical axis, and increase of the walk-off angle or off axial magnitude leads to larger separation distance. Finally, the case of high order original off axial vortex beam is also investigated.

HIGH-ENERGY X-RAY PINHOLE CAMERA FOR HIGH-RESOLUTION ELECTRON BEAM SIZE MEASUREMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, B.; Morgan, J.; Lee, S.H.

The Advanced Photon Source (APS) is developing a multi-bend achromat (MBA) lattice based storage ring as the next major upgrade, featuring a 20-fold reduction in emittance. Combining the reduction of beta functions, the electron beam sizes at bend magnet sources may be reduced to reach 5 – 10 µm for 10% vertical coupling. The x-ray pinhole camera currently used for beam size monitoring will not be adequate for the new task. By increasing the operating photon energy to 120 – 200 keV, the pinhole camera’s resolution is expected to reach below 4 µm. The peak height of the pinhole imagemore » will be used to monitor relative changes of the beam sizes and enable the feedback control of the emittance. We present the simulation and the design of a beam size monitor for the APS storage ring.« less

Method for detecting a mass density image of an object

DOEpatents

Wernick, Miles N [Chicago, IL; Yang, Yongyi [Westmont, IL

2008-12-23

A method for detecting a mass density image of an object. An x-ray beam is transmitted through the object and a transmitted beam is emitted from the object. The transmitted beam is directed at an angle of incidence upon a crystal analyzer. A diffracted beam is emitted from the crystal analyzer onto a detector and digitized. A first image of the object is detected from the diffracted beam emitted from the crystal analyzer when positioned at a first angular position. A second image of the object is detected from the diffracted beam emitted from the crystal analyzer when positioned at a second angular position. A refraction image is obtained and a regularized mathematical inversion algorithm is applied to the refraction image to obtain a mass density image.

Fatigue and Fracture Characterization of GlasGridRTM Reinforced Asphalt Concrete Pavement

NASA Astrophysics Data System (ADS)

Safavizadeh, Seyed Amirshayan

The purpose of this research is to develop an experimental and analytical framework for describing, modeling, and predicting the reflective cracking patterns and crack growth rates in GlasGridRTM-reinforced asphalt pavements. In order to fulfill this objective, the effects of different interfacial conditions (mixture and tack coat type, and grid opening size) on reflective cracking-related failure mechanisms and the fatigue and fracture characteristics of fiberglass grid-reinforced asphalt concrete beams were studied by means of four- and threepoint bending notched beam fatigue tests (NBFTs) and cyclic and monotonic interface shear tests. The digital image correlation (DIC) technique was utilized for obtaining the displacement and strain contours of specimen surfaces during each test. The DIC analysis results were used to develop crack tip detection methods that were in turn used to determine interfacial crack lengths in the shear tests, and vertical and horizontal (interfacial) crack lengths in the notched beam fatigue tests. Linear elastic fracture mechanics (LEFM) principles were applied to the crack length data to describe the crack growth. In the case of the NBFTs, a finite element (FE) code was developed and used for modeling each beam at different stages of testing and back-calculating the stress intensity factors (SIFs) for the vertical and horizontal cracks. The local effect of reinforcement on the stiffness of the system at a vertical crack-interface intersection or the resistance of the grid system to the deflection differential at the joint/crack (hereinafter called joint stiffness) for GlasGrid-reinforced asphalt concrete beams was determined by implementing a joint stiffness parameter into the finite element code. The strain level dependency of the fatigue and fracture characteristics of the GlasGrid-reinforced beams was studied by performing four-point bending notched beam fatigue tests at strain levels of 600, 750, and 900 microstrain. These beam tests were conducted at 15°C, 20°C, and 23°C, with the main focus being to find the characteristics at 20°C. The results obtained from the tests at the different temperatures were used to investigate the effects of temperature on the reflective cracking performance of the gridreinforced beam specimens. The temperature tests were also used to investigate the validity of the time-temperature superposition (t-TS) principle in shear and the beam fatigue performance of the grid-reinforced specimens. The NBFT results suggest that different interlayer conditions do not reflect a unique failure mechanism, and thus, in order to predict and model the performance of grid-reinforced pavement, all the mechanisms involved in weakening its structural integrity, including damage within the asphalt layers and along the interface, must be considered. The shear and beam fatigue test results suggest that the grid opening size, interfacial bond quality, and mixture type play important roles in the reflective cracking performance of GlasGrid-reinforced asphalt pavements. According to the NBTF results, GlasGrid reinforcement retards reflective crack growth by stiffening the composite system and introducing a joint stiffness parameter. The results also show that the higher the bond strength and interlayer stiffness values, the higher the joint stiffness and retardation effects. The t-TS studies proved the validity of this principle in terms of the reflective crack growth of the grid-reinforced beam specimens and the shear modulus and shear strength of the grid-reinforced interfaces.

Fast Beam-Based BPM Calibration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bertsche, K.; Loos, H.; Nuhn, H.-D.

2012-10-15

The Alignment Diagnostic System (ADS) of the LCLS undulator system indicates that the 33 undulator quadrupoles have extremely high position stability over many weeks. However, beam trajectory straightness and lasing efficiency degrade more quickly than this. A lengthy Beam Based Alignment (BBA) procedure must be executed every two to four weeks to re-optimize the X-ray beam parameters. The undulator system includes RF cavity Beam Position Monitors (RFBPMs), several of which are utilized by an automatic feedback system to align the incoming electron-beam trajectory to the undulator axis. The beam trajectory straightness degradation has been traced to electronic drifts of themore » gain and offset of the BPMs used in the beam feedback system. To quickly recover the trajectory straightness, we have developed a fast beam-based procedure to recalibrate the BPMs. This procedure takes advantage of the high-precision monitoring capability of the ADS, which allows highly repeatable positioning of undulator quadrupoles. This report describes the ADS, the position stability of the LCLS undulator quadrupoles, and some results of the new recovery procedure.« less

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: On the gravitational-deceleration initiation of the phase transition of gas to a Bose condensate

NASA Astrophysics Data System (ADS)

Rivlin, L. A.

2008-01-01

A scenario of the experiment on the observation of the isothermal Bose condensation of cooled gas with increasing the concentration of atoms caused by the deceleration of a vertical atomic beam in the gravitational field resulting in a decrease in the phase transition critical temperature below the gas temperature is considered. Coherent phenomena accompanying the evolution of the Bose condensate during further beam deceleration are pointed out.

A grid amplifier

NASA Technical Reports Server (NTRS)

Kim, Moonil; Weikle, Robert M., II; Hacker, Jonathan B.; Delisio, Michael P.; Rutledge, David B.; Rosenberg, James J.; Smith, R. P.

1991-01-01

A 50-MESFET grid amplifier is reported that has a gain of 11 dB at 3.3 GHz. The grid isolates the input from the output by using vertical polarization for the input beam and horizontal polarization for the transmitted output beam. The grid unit cell is a two-MESFET differential amplifier. A simple calibration procedure allows the gain to be calculated from a relative power measurement. This grid is a hybrid circuit, but the structure is suitable for fabrication as a monolithic wafer-scale integrated circuit, particularly at millimeter wavelengths.

Small Aperture BPM to Quadrupole Assembly Tolerance Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fong, K. W.

2010-12-07

The LCLS injector and linac systems utilize a series of quadrupole magnets with a beam position monitor (BPM) captured in the magnet pole tips. The BPM measures the electron beam position by comparing the electrical signal from 4 electrodes and interpolating beam position from these signals. The manufacturing tolerances of the magnet and BPM are critical in determining the mechanical precision of the electrodes relative to the nominal electron beam Z-axis. This study evaluates the statistical uncertainty of the electrodes center axis relative to the nominal electron beam axis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

González, M. A. Pagnan, E-mail: miguelangel.pagnan@hotmail.com; Mitsoura, E., E-mail: meleni@uaemex.mx; Oviedo, J.O. Hernández

Mycosis fungoides is a cutaneous lymphoma that accounts for 2–3% of all lymphomas. Several clinical studies have demonstrated the effectiveness of TSEBT (Total Skin Electron Beam Therapy) in patients with mycosis fungoides. It is important to develop this technique and make it available to a larger number of patients in Mexico. Because large fields for electron TSEBT are required in order to cover the entire body of the patient, beam characterization at conventional treatment distances is not sufficient and a calibration distance of 500cm or higher is required. Materials and methods: Calibration of radiochromic Gafchromic® EBT2 film (RCF) for electronsmore » was performed in a solid water phantom (Scanditronix Wellhöfer) at a depth of 1.4cm and a Source Axis Distance (SAD) of 100cm. A polynomial fit was applied to the calibration curve, in order to obtain the equation relating dose response with optical density. The spatial distribution is obtained in terms of percentage of the dose, placing 3×3cm samples of RCF on the acrylic screen, which is placed in front of the patient in order to obtain maximum absorbed dose on the skin, covering an area of 200×100cm{sup 2}. The Percentage Depth Dose (PDD) curve was obtained placing RCF samples at depths of 0, 1, 1.2, 1.4, 1.5, 2, 3, 4, 5, 6, 7, 8 and 9cm in the solid water phantom, irradiated with an ELEKTA SINERGY Linear Accelerator electron beam, with an energy of 6 MeV, at a Source Skin Distance (SSD) of 500cm, with 1000MU = 100Gy, with a cone of 40×40cm and gantry angle of 90°. The RCFs were scanned on a flatbed scanner (EPSON EXPRESSION 10000 XL) and the images were processed with the ImageJ program using a region of interest (ROI) of 1×1cm{sup 2}. Results: The relative spatial dose distribution and the percentage depth dose for a SSD of 500±0.5cm, over an area of 200×100cm{sup 2} was obtained, resulting to an effective maximum dose depth (Z{sub ref}) for electrons of 1.4±0.05cm. Using the same experimental data, horizontal and vertical beam profiles were also graphed, showing a horizontal symmetry of ±035%, horizontal flatness of ±3.62%, vertical symmetry of ±2.1% and vertical flatness of ±14.2%. Conclusions: The electron beam was characterized and the data obtained were useful to determine the spatial dose distribution to a SSD of 500±0.5cm, in an area of 200×100cm{sup 2}. Dose profiles were obtained both horizontally and vertically, thus allowing to assess electron beam symmetry and flatness. PDD analysis up to a depth of 9±0.05cm, has made possible to establish the depth of electron penetration, assuring an only skin irradiation treatment.« less

One-Micron Beams for Macromolecular Crystallography at GM/CA-CAT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoder, D. W.; Sanishvili, R.; Xu, S.

2010-06-23

GM/CA-CAT has developed a 1-{mu}m beam for challenging micro-diffraction experiments with macromolecular crystals (e.g. small crystals) and for radiation damage studies. Reflective (Kirkpatrick-Baez mirrors) and diffractive (Fresnel zone plates) optics have been used to focus the beam. Both cases are constrained by the need to maintain a small beam convergence. Using two different zone plates, 1.0x1.0 and 0.8x0.9 {mu}m{sup 2} (VxH,FWHM) beams were created at 15.2 keV and 18.5 keV, respectively. Additionally, by introducing a vertical focusing mirror upstream of the zone plate, a line focus at 15.2 keV was created (28x1.4 {mu}m{sup 2} VxH,FWHM) with the line oriented perpendicularmore » to the X-ray polarization and the crystal rotation axis. Crystal-mounting stages with nanometer resolution have been assembled to profile these beams and to perform diffraction experiments.« less

Benchmarking of measurement and simulation of transverse rms-emittance growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeon, Dong-O

2008-01-01

Transverse emittance growth along the Alvarez DTL section is a major concern with respect to the preservation of beam quality of high current beams at the GSI UNILAC. In order to define measures to reduce this growth appropriated tools to simulate the beam dynamics are indispensable. This paper is about the benchmarking of three beam dynamics simulation codes, i.e. DYNAMION, PARMILA, and PARTRAN against systematic measurements of beam emittances for different machine settings. Experimental set-ups, data reduction, the preparation of the simulations, and the evaluation of the simulations will be described. It was found that the measured 100%-rmsemittances behind themore » DTL exceed the simulated values. Comparing measured 90%-rms-emittances to the simulated 95%-rms-emittances gives fair to good agreement instead. The sum of horizontal and vertical emittances is even described well by the codes as long as experimental 90%-rmsemittances are compared to simulated 95%-rms-emittances. Finally, the successful reduction of transverse emittance growth by systematic beam matching is reported.« less

Straightness measurement using laser beam straight datum

NASA Astrophysics Data System (ADS)

Uchikoshi, Junichi; Shimada, Shoichi; Ikawa, Naoya; Komura, Akio

1995-08-01

Using the direction stabilized laser beam as a physical straight datum, instead of the tangible reference surface, a method is proposed for the measurement of an error motion of a slide table and/or surface profile of mechanical components. A specially designed 2D position sensor/compensator for laser beam center is developed combining a quadrant photo-diode (QPD) position sensor for beam center and the piezo-compensator which compensates the beam shift from the center of QPD. By the use the sensor/compensator proposed, the positional and angular fluctuations of laser beam path is evaluated with nanometric resolution. Combining the sensor with the piezo-driven mirror compensator, the directional stabilizer for the laser beam is also designed in the same manner as the sensor/compensator. The stabilized He-Ne laser beam can be used as the metrological datum of straightness within the accuracy of 2 X 10 -8 rad. By mounting the position sensor/compensator on a slide table, the carriage with working distance of 1 m is so designed and built as to move straight along the stabilized laser beam. The carriage can be used as a mechanical straight datum with the accuracy equivalent to the laser beam stability.

21 CFR 892.5780 - Light beam patient position indicator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Light beam patient position indicator. 892.5780 Section 892.5780 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Therapeutic Devices § 892.5780 Light beam patient position...

Experimental Validation of an Ion Beam Optics Code with a Visualized Ion Thruster

NASA Astrophysics Data System (ADS)

Nakayama, Yoshinori; Nakano, Masakatsu

For validation of an ion beam optics code, the behavior of ion beam optics was experimentally observed and evaluated with a two-dimensional visualized ion thruster (VIT). Since the observed beam focus positions, sheath positions and measured ion beam currents were in good agreement with the numerical results, it was confirmed that the numerical model of this code was appropriated. In addition, it was also confirmed that the beam focus position was moved on center axis of grid hole according to the applied grid potentials, which differs from conventional understanding/assumption. The VIT operations may be useful not only for the validation of ion beam optics codes but also for the fundamental and intuitive understanding of the Child Law Sheath theory.

Walking-Beam Solar-Cell Conveyor

NASA Technical Reports Server (NTRS)

Feder, H.; Frasch, W.

1982-01-01

Microprocessor-controlled walking-beam conveyor moves cells between work stations in automated assembly line. Conveyor has arm at each work station. In unison arms pick up all solar cells and advance them one station; then beam retracks to be in position for next step. Microprocessor sets beam stroke, speed, and position.

Assessment of the Horizontal and Vertical Position of Mental Foramen in Indian Population in Terms of Age and Sex in Dentate Subjects by Pano-ramic Radiographs: A Retrospective Study with Review of Literature.

PubMed

Parnami, Priyanka; Gupta, Deepak; Arora, Vishal; Bhalla, Saurabh; Kumar, Adarsh; Malik, Rashi

2015-01-01

To familiarize new criteria to access vertical position of mental foramen in panoramic radiographs. Furthermore, to determine and compare the position and symmetry of mental foramen in horizontal as well as in vertical plane in Indian population and to compare the results with those reported for other populations in the literature. Further gender differences in mental foramen position were also accessed to comment on the reliability of panoramic radiographs for sex determination. Methods and Material : Six hundred digital panoramic radiographs were selected and studied regarding the location and symmetry of mental foramen. They were also compared with the other studies in the literature. The method employed is similar to that described by Al Jasser and Nwoku for horizontal position and Fishal et al. for vertical position of mental foramen. Certain modifications were carried out in Fishal's criteria for vertical position assessment. Results : The commonest position of the mental foramen in horizontal plane was in line with the longitudinal axis of the second premolar (61.0%) while in vertical plane it was found to be located inferior to the apex of second premolar (72.2%). Conclusion : Mental foramen exists in different locations and possesses many variations. Hence, Individual, gender, age, race and assessing technique largely influence these variations. It suggests that the clinicians should carefully identify these anatomical landmarks, by analyzing all influencing factors, prior to their diagnostic or the other dental, surgical and implant operation.

Identification and control of plasma vertical position using neural network in Damavand tokamak.

PubMed

Rasouli, H; Rasouli, C; Koohi, A

2013-02-01

In this work, a nonlinear model is introduced to determine the vertical position of the plasma column in Damavand tokamak. Using this model as a simulator, a nonlinear neural network controller has been designed. In the first stage, the electronic drive and sensory circuits of Damavand tokamak are modified. These circuits can control the vertical position of the plasma column inside the vacuum vessel. Since the vertical position of plasma is an unstable parameter, a direct closed loop system identification algorithm is performed. In the second stage, a nonlinear model is identified for plasma vertical position, based on the multilayer perceptron (MLP) neural network (NN) structure. Estimation of simulator parameters has been performed by back-propagation error algorithm using Levenberg-Marquardt gradient descent optimization technique. The model is verified through simulation of the whole closed loop system using both simulator and actual plant in similar conditions. As the final stage, a MLP neural network controller is designed for simulator model. In the last step, online training is performed to tune the controller parameters. Simulation results justify using of the NN controller for the actual plant.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silvani, M. I.; Almeida, G. L.; Lopes, R. T.

Radiographic images acquired with point-like gamma-ray sources exhibit a desirable low penumbra effects specially when positioned far away from the set object-detector. Such an arrangement frequently is not affordable due to the limited flux provided by a distant source. A closer source, however, has two main drawbacks, namely the degradation of the spatial resolution - as actual sources are only approximately punctual - and the non-homogeneity of the beam hitting the detector, which creates a false attenuation map of the object being inspected. This non-homogeneity is caused by the beam divergence itself and by the different thicknesses traversed the beammore » even if the object were an homogeneous flat plate. In this work, radiographic images of objects with different geometries, such as flat plates and pipes have undergone a correction of beam divergence and attenuation addressing the experimental verification of the capability and soundness of an algorithm formerly developed to generate and process synthetic images. The impact of other parameters, including source-detector gap, attenuation coefficient, ratio defective-to-main hull thickness and counting statistics have been assessed for specifically tailored test-objects aiming at the evaluation of the ability of the proposed method to deal with different boundary conditions. All experiments have been carried out with an X-ray sensitive Imaging Plate and reactor-produced {sup 198}Au and {sup 165}Dy sources. The results have been compared with other technique showing a better capability to correct the attenuation map of inspected objects unveiling their inner structure otherwise concealed by the poor contrast caused by the beam divergence and attenuation, in particular for those regions far apart from the vertical of the source.« less

Simulation of turn-by-turn passage of protons through the H-minus stripping foil in booster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gardner, C.

Equations for transverse emittance growth due to multiple passes of circulating proton beam through the H-minus stripping foil in Booster were developed in [1]. These were based on simple principles of statistics and simple assumptions about the initial distribution of particles incident on the foil. It was assumed there that the foil dimensions and position of the incoming beam are such that all particles hit the foil on every turn around the machine. In the present note we assume only that all incoming H-minus ions from Linac hit the foil and are stripped of their electrons. The resulting protons circulatemore » indefinitely around the machine. Setups in which the foil width is reduced so that not all protons hit the foil on every turn are studied here by simulation. The aim is to determine the effectiveness of such setups in reducing the emittance growth of circulating proton beam during the injection of H-minus beam. The simulations also serve as a check of the equations developed in [1], and vice versa. The particulars of the simulation setup are given in Sections 1 through 11. Figures 1 through 12 show simulation results for the case in which all particles hit the foil on every turn. The results are in good agreement with those obtained from the equations of reference [1]. Figures 13 through 19 show simulation results for various setups in which the foil width is reduced. These results are summarized in Section 12. In all gures the horizontal axis gives the turn number. The unit of the vertical axis is micrometers ( m) in all plots of emittance.« less

Novel Microstrip Patch Antennas with Frequency Agility, Polarization Reconfigurability, Dual Null Steering Capability and Phased Array Antenna with Beam Steering Performance

NASA Astrophysics Data System (ADS)

Babakhani, Behrouz

Nowadays the wireless communication technology is playing an important role in our daily life. People use wireless devices not only as a conventional communication device but also as tracking and navigation tool, web browsing tool, data storage and transfer tool and so for many other reasons. Based on the user demand, wireless communication engineers try to accommodate as many as possible wireless systems and applications in a single device and therefore, creates a multifunctional device. Antenna, as an integral part of any wireless communication systems, should also be evolved and adjusted with development of wireless transceiver systems. Therefore multifunctional antennas have been introduced to support and enhance the functionality on modern wireless systems. The main focus and contribution of this thesis is design of novel multifunctional microstrip antennas with frequency agility, polarization reconfigurablity, dual null steering capability and phased array antenna with beam steering performance. In this thesis, first, a wide bandwidth(1.10 GHz to 1.60 GHz) right-handed circularly polarized (RHCP) directional antenna for global positioning system (GPS) satellite receive application has been introduced which covers all the GPS bands starting from L1 to L5. This design consists of two crossed bow-tie dipole antennas fed with sequentially phase rotated feed network backed with an artificial high impedance surface (HIS) structure to generate high gain directional radiation patterns. This design shows good CP gain and axial ratio (AR) and wide beamwidth performance. Although this design has good radiation quality, the size and the weight can be reduced as future study. In the second design, a frequency agile antenna was developed which also covers the L-band (L1 to L5) satellite communication frequencies. This frequency agile antenna was designed and realized by new implementation of varactor diodes in the geometry of a circular patch antenna. Beside wide frequency agility (1.17 GHz to 1.58 GHz), full polarization reconfiguration was added to the design by controlling ports excitation of circular patch using RF switches (vertical linear, horizontal linear, right-handed circular polarization (RHCP) and left-handed circular polarization (LHCP)). This deign maintains good gain and radiation efficiency over the tunable range as well as acceptable co-polarization and cross-polarization separation for different polarizations. Since many communications applications require beam steering ability, in our third design, we designed and developed a linear phased array antenna using a modified version of our frequency agile polarization reconfigurable antenna for beam steering applications. This design offers wide frequency agility (1.50 GHz to 2.40 GHz), full polarization reconfiguration (vertical linear, horizontal linear, LHCP and RHCP) as well as beam steering of +/-52° and +/-28° at 1.5 GHz and 2.4 GHz, respectively. In this 1x4 array, the excitation magnitude and phase of each element was controlled by an analog beamforming feed network (BFN) for beam steering purposes. The required excitation for each element to steer the beam toward a desired location was calculated using projection matrix method (PMM) which uses measured active element pattern (AEP) as its input. This array antenna performance for frequency agility, radiation quality for each polarization and beam steering capability was obtained in the acceptable range. In the last design, the full spherical dual null steering capability of a triple mode circular microstrip patch antenna was investigated. By combining the radiation patterns of three individual modes of microstrip circular patch antenna, two nulls have been generated. These nulls can be repositioned in the upper hemisphere by controlling excitation ratio of each mode. The modes excitation ratio to steer the nulls toward the desired positions was calculated using a derivative free hybrid optimization method. This optimization method uses particle swarm optimization (PSO) combined with pattern search (PS) to find the optimum modes excitation ratio which minimizes the received power at the null positions. The calculated coefficients were applied to the multimode antenna using an analog BFN. This design shows an independent dual null steering with null depth of around 20 dB. Discussion about the proposed antennas included detailed theoretical analysis, numerical simulation and optimizations, beam forming and null steering algorithms, fabrication of the antennas and its control/beamforming feed networks along with the associated bias networks, microcontroller units, and finally its characterization (impedance matching, gain and 2D and 3D radiation patterns). The research work was performed at the Antenna and Microwave Lab (AML) which has the required resources including full wave analysis tools, PCB milling machine, surface mount component soldering station, vector network analyzers, and far-field/spherical near-field radiation pattern measurement system.

Development of the beam extraction synchronization system at the Fermilab Booster

NASA Astrophysics Data System (ADS)

Seiya, K.; Chaurize, S.; Drennan, C. C.; Pellico, W.; Sullivan, T.; Triplett, A. K.; Waller, A. M.

2015-11-01

The new beam extraction synchronization control system called "Magnetic Cogging" was developed at the Fermilab Booster and it replaces a system called "RF Cogging" as part of the Proton Improvement Plan (PIP).[1] The flux throughput goal for the PIP is 2.2×1017 protons per hour, which is double the present flux. The flux increase will be accomplished by doubling the number of beam cycles which, in turn, will double the beam loss in the Booster accelerator if nothing else is done. The Booster accelerates beam from 400 MeV to 8 GeV and extracts it to the Main Injector (MI) or Recycler Ring (RR). Cogging controls the beam extraction gap position which is created early in the Booster cycle and synchronizes the gap to the rising edge of the Booster extraction kicker and the MI/RR injection kicker. The RF Cogging system controls the gap position by changing only the radial position of the beam thus limiting the beam aperture and creating beam loss due to beam scraping. The Magnetic Cogging system controls the gap position with the magnetic field of the dipole correctors while the radial position feedback keeps the beam on a central orbit. Also with Magnetic Cogging the gap creation can occur earlier in the Booster cycle when the removed particles are at a lower energy. Thus Magnetic Cogging reduces the deposited energy of the lost particles (beam energy loss) and results in less beam loss activation. Energy loss was reduced by 40% by moving the gap creation energy from 700 MeV to 400 MeV when the Booster Cogging system was switched from RF Cogging to Magnetic Cogging in March 2015.

Satellite radar interferometry for monitoring ice sheet motion: application to an antarctic ice stream.

PubMed

Goldstein, R M; Engelhardt, H; Kamb, B; Frolich, R M

1993-12-03

Satellite radar interferometry (SRI) provides a sensitive means of monitoring the flow velocities and grounding-line positions of ice streams, which are indicators of response of the ice sheets to climatic change or internal instability. The detection limit is about 1.5 millimeters for vertical motions and about 4 millimeters for horizontal motions in the radar beam direction. The grounding line, detected by tidal motions where the ice goes afloat, can be mapped at a resolution of approximately 0.5 kilometer. The SRI velocities and grounding line of the Rutford Ice Stream, Antarctica, agree fairly well with earlier ground-based data. The combined use of SRI and other satellite methods is expected to provide data that will enhance the understanding of ice stream mechanics and help make possible the prediction of ice sheet behavior.

Difference in the relative biological effectiveness and DNA damage repair processes in response to proton beam therapy according to the positions of the spread out Bragg peak.

PubMed

Hojo, Hidehiro; Dohmae, Takeshi; Hotta, Kenji; Kohno, Ryosuke; Motegi, Atsushi; Yagishita, Atsushi; Makinoshima, Hideki; Tsuchihara, Katsuya; Akimoto, Tetsuo

2017-07-03

Cellular responses to proton beam irradiation are not yet clearly understood, especially differences in the relative biological effectiveness (RBE) of high-energy proton beams depending on the position on the Spread-Out Bragg Peak (SOBP). Towards this end, we investigated the differences in the biological effect of a high-energy proton beam on the target cells placed at different positions on the SOBP, using two human esophageal cancer cell lines with differing radiosensitivities. Two human esophageal cancer cell lines (OE21, KYSE450) with different radiosensitivities were irradiated with a 235-MeV proton beam at 4 different positions on the SOBP (position #1: At entry; position #2: At the proximal end of the SOBP; position #3: Center of the SOBP; position #4: At the distal end of the SOBP), and the cell survivals were assessed by the clonogenic assay. The RBE 10 for each position of the target cell lines on the SOBP was determined based on the results of the cell survival assay conducted after photon beam irradiation. In addition, the number of DNA double-strand breaks was estimated by quantitating the number of phospho-histone H2AX (γH2AX) foci formed in the nuclei by immunofluorescence analysis. In regard to differences in the RBE of a proton beam according to the position on the SOBP, the RBE value tended to increase as the position on the SOBP moved distally. Comparison of the residual number of γH2AX foci at the end 24 h after the irradiation revealed, for both cell lines, a higher number of foci in the cells irradiated at the distal end of the SOPB than in those irradiated at the proximal end or center of the SOBP. The results of this study demonstrate that the RBE of a high-energy proton beam and the cellular responses, including the DNA damage repair processes, to high-energy proton beam irradiation, differ according to the position on the SOBP, irrespective of the radiosensitivity levels of the cell lines.

The high-energy x-ray diffraction and scattering beamline at the Canadian Light Source

NASA Astrophysics Data System (ADS)

Gomez, A.; Dina, G.; Kycia, S.

2018-06-01

The optical design for the high-energy x-ray diffraction and scattering beamline of the Brockhouse sector at the Canadian Light Source is described. The design is based on a single side-bounce silicon focusing monochromator that steers the central part of a high-field permanent magnet wiggler beam into the experimental station. Two different configurations are proposed: a higher energy resolution with vertical focusing and a lower energy resolution with horizontal and vertical focusing. The monochromator will have the possibility of mounting three crystals: one crystal optimized for 35 keV that focuses in the horizontal and vertical directions using reflection (1,1,1) and two other crystals both covering the energies above 40 keV: one with only vertical focusing and another one with horizontal and vertical focusing. The geometry of the last two monochromator crystals was optimized to use reflections (4,2,2) and (5,3,3) to cover the broad energy range from 40 to 95 keV.

Systems and methods for detecting an image of an object by use of an X-ray beam having a polychromatic distribution

DOEpatents

Parham, Christopher; Zhong, Zhong; Pisano, Etta; Connor, Dean; Chapman, Leroy D.

2010-06-22

Systems and methods for detecting an image of an object using an X-ray beam having a polychromatic energy distribution are disclosed. According to one aspect, a method can include detecting an image of an object. The method can include generating a first X-ray beam having a polychromatic energy distribution. Further, the method can include positioning a single monochromator crystal in a predetermined position to directly intercept the first X-ray beam such that a second X-ray beam having a predetermined energy level is produced. Further, an object can be positioned in the path of the second X-ray beam for transmission of the second X-ray beam through the object and emission from the object as a transmitted X-ray beam. The transmitted X-ray beam can be directed at an angle of incidence upon a crystal analyzer. Further, an image of the object can be detected from a beam diffracted from the analyzer crystal.

Low-Profile, Dual-Wavelength, Dual-Polarized Antenna

NASA Technical Reports Server (NTRS)

Carswell, James R.

2010-01-01

A single-aperture, low-profile antenna design has been developed that supports dual-polarization and simultaneous operation at two wavelengths. It realizes multiple beams in the elevation plane, and supports radiometric, radar, and conical scanning applications. This antenna consists of multiple azimuth sticks, with each stick being a multilayer, hybrid design. Each stick forms the h-plane pattern of the C and Ku-band vertically and horizontally polarized antenna beams. By combining several azimuth sticks together, the elevation beam is formed. With a separate transceiver for each stick, the transmit phase and amplitude of each stick can be controlled to synthesize a beam at a specific incidence angle and to realize a particular side-lobe pattern. By changing the transmit phase distribution through the transceivers, the transmit antenna beam can be steered to different incidence angles. By controlling the amplitude distribution, different side lobe patterns and efficiencies can be realized. The receive beams are formed using digital beam synthesis techniques, resulting in very little loss in the receive path, thus enabling a very-low loss receive antenna to support passive measurements.

Snakes, rotators, serpents and the octahedral group

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fieguth, T.

1986-04-01

Specific configurations of horizontal and vertical bending magnets are given that, when acting on the spin polarization vector of a particle beam, generate a group of 24 operators isomorphic to the group of rotational symmetries of a cube, known as the octahedral group. Some of these configurations have the feature of converting transversely polarized beams to longitudinally polarized beams (or vice versa) at the midpoint of the configuration for, in principle, all beam energies. Since the first order optical transfer matrix for each half of these configurations is nearly that of a drift region, the external geometry remains unchanged andmore » midpoint dispersion is not introduced. Changing field strengths and/or polarities allows a configuration to serve as either a Snake(1/sup st/ or 2/sup nd/ kind) or a Rotator, where in both cases the spin polarization is longitudinal at the midpoint. In this conceptualization, emphasis has been placed on electron beams and, indeed, for these beams some practical applications can be envisioned. However, due to the relatively high integrated field strengths required, application of these concepts to proton beams may be more promising.« less

Free-electron laser power beaming to satellites at China Lake, California

NASA Astrophysics Data System (ADS)

Bennett, Harold E.; Rather, John D.; Montgomery, Edward E.

1994-05-01

Laser power beaming of energy through the atmosphere to a satellite can extend its lifetime by maintaining the satellite batteries in operating condition. An alternate propulsion system utilizing power beaming will also significantly reduce the initial insertion cost of these satellites, which now are as high as $72,000/lb for geosynchronous orbit. Elements of the power beaming system are a high-power laser, a large diameter telescope to reduce diffractive losses, an adaptive optic beam conditioning system and possibly a balloon or aerostat carrying a large mirror to redirect the laser beam to low earth orbit satellites after it has traversed most of the earth's atmosphere vertically. China Lake, California has excellent seeing, averages 260 cloud-free days/year, has the second largest geothermal plant in the United States nearby for power, groundwater from the lake for cooling water, and is at the center of one of the largest restricted airspaces in the United States. It is an ideal site for such a laser power beaming system. Technological challenges in building such a system and installing it at China Lake are discussed.

Free-electron laser power beaming to satellites at China Lake, California

NASA Astrophysics Data System (ADS)

Bennett, Harold E.; Rather, John D.; Montgomery, Edward E.

1994-05-01

Laser power beaming of energy through the atmosphere to a satellite can extend its lifetime by maintaining the satellite batteries in operating condition. An alternate propulsion system utilizing power beaming will also significantly reduce the initial insertion cost of these satellites, which now are as high as $DLR72,000/lb for geosynchronous orbit. Elements of the power beaming system are a high-power laser, a large diameter telescope to reduce diffractive losses, an adaptive optic beam conditioning system and possibly a balloon or aerostat carrying a large mirror to redirect the laser beam to low earth orbit satellites after it has traversed most of the earth's atmosphere vertically. China Lake, California has excellent seeing, averages 260 cloud-free days/year, has the second largest geothermal plant in the United States nearby for power, groundwater from the lake for cooling water, and is at the center of one of the largest restricted airspaces in the United States. It is an ideal site for such a laser power beaming system. Technological challenges in building such a system and installing it at China Lake will be discussed.

Effect of gravity on vertical eye position.

PubMed

Pierrot-Deseilligny, C

2009-05-01

There is growing evidence that gravity markedly influences vertical eye position and movements. A new model for the organization of brainstem upgaze pathways is presented in this review. The crossing ventral tegmental tract (CVTT) could be the efferent tract of an "antigravitational" pathway terminating at the elevator muscle motoneurons in the third nerve nuclei and comprising, upstream, the superior vestibular nucleus and y-group, the flocculus, and the otoliths. This pathway functions in parallel to the medial longitudinal fasciculus pathways, which control vertical eye movements made to compensate for all vertical head movements and may also comprise the "gravitational" vestibular pathways, involved in the central reflection of the gravity effect. The CVTT could provide the upgaze system with the supplement of tonic activity required to counteract the gravity effect expressed in the gravitational pathway, being permanently modulated according to the static positions of the head (i.e., the instantaneous gravity vector) between a maximal activity in the upright position and a minimal activity in horizontal positions. Different types of arguments support this new model. The permanent influence of gravity on vertical eye position is strongly suggested by the vertical slow phases and nystagmus observed after rapid changes in hypo- or hypergravity. The chin-beating nystagmus, existing in normal subjects with their head in the upside-down position, suggests that gravity is not compensated for in the downgaze system. Upbeat nystagmus due to brainstem lesions, most likely affecting the CVTT circuitry, is improved when the head is in the horizontal position, suggesting that this circuitry is involved in the counteraction of gravity between the upright and horizontal positions of the head. In downbeat nystagmus due to floccular damage, in which a permanent hyperexcitation of the CVTT could exist, a marked influence of static positions of the head is also observed. Finally, the strongest argument supporting a marked role of gravity in vertical eye position is that the eye movement alterations observed in the main, typical physiological and pathological conditions are precisely those that would be expected from a direct effect of gravity on the eyeballs, with, moreover, no single alternative interpretation existing so far that could account for all these different types of findings.

Precision alignment device

DOEpatents

Jones, N.E.

1988-03-10

Apparatus for providing automatic alignment of beam devices having an associated structure for directing, collimating, focusing, reflecting, or otherwise modifying the main beam. A reference laser is attached to the structure enclosing the main beam producing apparatus and produces a reference beam substantially parallel to the main beam. Detector modules containing optical switching devices and optical detectors are positioned in the path of the reference beam and are effective to produce an electrical output indicative of the alignment of the main beam. This electrical output drives servomotor operated adjustment screws to adjust the position of elements of the structure associated with the main beam to maintain alignment of the main beam. 5 figs.

Precision alignment device

DOEpatents

Jones, Nelson E.

1990-01-01

Apparatus for providing automatic alignment of beam devices having an associated structure for directing, collimating, focusing, reflecting, or otherwise modifying the main beam. A reference laser is attached to the structure enclosing the main beam producing apparatus and produces a reference beam substantially parallel to the main beam. Detector modules containing optical switching devices and optical detectors are positioned in the path of the reference beam and are effective to produce an electrical output indicative of the alignment of the main beam. This electrical output drives servomotor operated adjustment screws to adjust the position of elements of the structure associated with the main beam to maintain alignment of the main beam.