WorldWideScience

Sample records for beam loss patterns

  1. LHC beam loss pattern recognition

    CERN Document Server

    Marsili, A; Puzo, P

    2011-01-01

    One of the systems protecting CERN’s Large Hadron Collider (LHC) is the Beam Loss Monitoring system (BLM). More than 3600 monitors are installed around the ring. The beam losses are permanently integrated over 12 different time intervals (from 40 microseconds to 84 seconds). When any loss exceeds the thresholds defined for the integration window, the beam is removed from the machine. Understanding the origin of a beam loss is crucial for machine operation, as it can help to avoid a repetition of the same scenario. The signals read from given monitors can be considered as entries of a vector. This article presents how a loss map of unknown cause can be decomposed using vector based analysis derived from well-known loss scenarios. The algorithms achieving this decomposition are described, as well as the accuracy of the results.

  2. Beam Loss Patterns at the LHC Collimators Measurements & Simulations

    CERN Document Server

    Böhlen, Till Tobias

    2008-01-01

    The Beam Loss Monitoring (BLM) system of the Large Hadron Collider (LHC) detects particle losses of circulating beams and initiates an emergency extraction of the beam in case that the BLM thresholds are exceeded. This protection is required as energy deposition in the accelerator equipment due to secondary shower particles can reach critical levels; causing damage to the beam-line components and quenches of superconducting magnets. Robust and movable beam line elements, so-called collimators, are the aperture limitations of the LHC. Consequently, they are exposed to the excess of lost beam particles and their showers. Proton loss patterns at LHC collimators have to be determined to interpret the signal of the BLM detectors and to set adequate BLM thresholds for the protection of collimators and other equipment in case of unacceptably increased loss rates. The first part of this work investigates the agreement of BLM detector measurements with simulations for an LHC-like collimation setup. The setup consists ...

  3. Identification and Classification of Beam Loss Patterns in the Large Hadron Collider

    CERN Document Server

    Panagiotis, Theodoropoulos; Valentino, Gianluca; Redaelli, Stefano; Herbster, Mark

    The Large Hadron Collider, is the largest particle accelerator ever built, achieving record beam energy and beam intensity. Beam losses are unavoidable and can risk the safety of accelerator’s components. Beam loss maps are used to validate the collimation system, designed to protect the accelerator against beam losses. The complexity of this system requires well defined inspection methods and well defined case studies that ensure normal operation and efficient performance evaluation. In this work, enhancements are proposed to the existing validation methods with extensions towards automating the inspection mechanisms, introducing pattern recognition and statistical learning methods.

  4. Identification of LHC beam loss mechanism : a deterministic treatment of loss patterns

    CERN Document Server

    Marsili, Aurélien

    CERN's Large Hadron Collider (LHC) is the largest machine ever built, with a total circumference of 26.7 km; and it is the most powerful accelerator ever, both in beam energy and beam intensity. The main magnets are superconducting, keeping the particles into two counter circulating beams, which collide in four interaction points. CERN and the LHC will be described in chap. 1. The superconducting magnets of the LHC have to be protected against particle losses. Depending on the number of lost particles, the coils of the magnets will become normal conducting and/or will be damaged. To avoid these events a beam loss monitoring (BLM) system was installed to measure the particle loss rates. If the predefined safe thresholds of loss rates are exceeded, the beams are directed out of the accelerator ring towards the beam dump. The detectors of the BLM system are mainly ionization chambers located outside of the cryostats. In total, about 3500 ionisation chambers are installed. Further challenges include the high dyna...

  5. Optimization of electron beam patterned hydrogen silsesquioxane mask edge roughness for low-loss silicon waveguides

    Science.gov (United States)

    Wood, Michael G.; Chen, Li; Burr, Justin R.; Reano, Ronald M.

    2014-01-01

    We carried out a multiparameter fabrication study designed to reduce the line edge roughness (LER) of electron beam (e-beam) patterned hydrogen silsesquioxane resist for the purpose of producing low-loss silicon strip waveguides. Reduced mask roughness was achieved for 50°C pre-exposure baking, 5000 μC/cm2 dose with a beam spot size more than twice as large as the electron beam step size, development in 25% tetramethylammonium hydroxide and postdevelopment baking with rapid thermal annealing in an O2 ambient at 1000°C. The LER caused by pattern fracturing and stage stitches was reduced with multipass writing and per-pass linear and rotational offsets. Si strip waveguides patterned with the optimized mask have root-mean-square sidewall roughness of 2.1 nm with a correlation length of 94 nm, as measured by three-dimensional atomic force microscopy. Measured optical propagation losses of these waveguides across the telecommunications C-band were 2.5 and 2.8 dB/cm for the transverse magnetic and transverse electric modes, respectively. These reduced loss waveguides enable the fabrication of advanced planar lightwave circuit topologies.

  6. Beam Loss in Linacs

    CERN Document Server

    Plum, M A

    2016-01-01

    Beam loss is a critical issue in high-intensity accelerators, and much effort is expended during both the design and operation phases to minimize the loss and to keep it to manageable levels. As new accelerators become ever more powerful, beam loss becomes even more critical. Linacs for H- ion beams, such as the one at the Oak Ridge Spallation Neutron Source, have many more loss mechanisms compared to H+ (proton) linacs, such as the one being designed for the European Spallation Neutron Source. Interesting H- beam loss mechanisms include residual gas stripping, H+ capture and acceleration, field stripping, black-body radiation and the recently discovered intra-beam stripping mechanism. Beam halo formation, and ion source or RF turn on/off transients, are examples of beam loss mechanisms that are common for both H+ and H- accelerators. Machine protection systems play an important role in limiting the beam loss.

  7. Simulations and measurements of beam loss patterns at the CERN Large Hadron Collider

    Science.gov (United States)

    Bruce, R.; Assmann, R. W.; Boccone, V.; Bracco, C.; Brugger, M.; Cauchi, M.; Cerutti, F.; Deboy, D.; Ferrari, A.; Lari, L.; Marsili, A.; Mereghetti, A.; Mirarchi, D.; Quaranta, E.; Redaelli, S.; Robert-Demolaize, G.; Rossi, A.; Salvachua, B.; Skordis, E.; Tambasco, C.; Valentino, G.; Weiler, T.; Vlachoudis, V.; Wollmann, D.

    2014-08-01

    The CERN Large Hadron Collider (LHC) is designed to collide proton beams of unprecedented energy, in order to extend the frontiers of high-energy particle physics. During the first very successful running period in 2010-2013, the LHC was routinely storing protons at 3.5-4 TeV with a total beam energy of up to 146 MJ, and even higher stored energies are foreseen in the future. This puts extraordinary demands on the control of beam losses. An uncontrolled loss of even a tiny fraction of the beam could cause a superconducting magnet to undergo a transition into a normal-conducting state, or in the worst case cause material damage. Hence a multistage collimation system has been installed in order to safely intercept high-amplitude beam protons before they are lost elsewhere. To guarantee adequate protection from the collimators, a detailed theoretical understanding is needed. This article presents results of numerical simulations of the distribution of beam losses around the LHC that have leaked out of the collimation system. The studies include tracking of protons through the fields of more than 5000 magnets in the 27 km LHC ring over hundreds of revolutions, and Monte Carlo simulations of particle-matter interactions both in collimators and machine elements being hit by escaping particles. The simulation results agree typically within a factor 2 with measurements of beam loss distributions from the previous LHC run. Considering the complex simulation, which must account for a very large number of unknown imperfections, and in view of the total losses around the ring spanning over 7 orders of magnitude, we consider this an excellent agreement. Our results give confidence in the simulation tools, which are used also for the design of future accelerators.

  8. Simulations and measurements of beam loss patterns at the CERN Large Hadron Collider

    CERN Document Server

    Bruce, R; Boccone, V; Bracco, C; Brugger, M; Cauchi, M; Cerutti, F; Deboy, D; Ferrari, A; Lari, L; Marsili, A; Mereghetti, A; Mirarchi, D; Quaranta, E; Redaelli, S; Robert-Demolaize, G; Rossi, A; Salvachua, B; Skordis, E; Tambasco, C; Valentino, G; Weiler, T; Vlachoudis, V; Wollmann, D

    2014-01-01

    The CERN Large Hadron Collider (LHC) is designed to collide proton beams of unprecedented energy, in order to extend the frontiers of high-energy particle physics. During the first very successful running period in 2010--2013, the LHC was routinely storing protons at 3.5--4 TeV with a total beam energy of up to 146 MJ, and even higher stored energies are foreseen in the future. This puts extraordinary demands on the control of beam losses. An un-controlled loss of even a tiny fraction of the beam could cause a superconducting magnet to undergo a transition into a normal-conducting state, or in the worst case cause material damage. Hence a multi-stage collimation system has been installed in order to safely intercept high-amplitude beam protons before they are lost elsewhere. To guarantee adequate protection from the collimators, a detailed theoretical understanding is needed. This article presents results of numerical simulations of the distribution of beam losses around the LHC that have leaked out of the co...

  9. Fullerene-assisted electron-beam lithography for pattern improvement and loss reduction in InP membrane waveguide devices.

    Science.gov (United States)

    Jiao, Yuqing; Pello, Josselin; Mejia, Alonso Millan; Shen, Longfei; Smalbrugge, Barry; Geluk, Erik Jan; Smit, Meint; van der Tol, Jos

    2014-03-15

    In this Letter, we present a method to prepare a mixed electron-beam resist composed of a positive resist (ZEP520A) and C60 fullerene. The addition of C60 to the ZEP resist changes the material properties under electron beam exposure significantly. An improvement in the thermal resistance of the mixed material has been demonstrated by fabricating multimode interference couplers and coupling regions of microring resonators. The fabrication of distributed Bragg reflector structures has shown improvement in terms of pattern definition accuracy with respect to the same structures fabricated with normal ZEP resist. Straight InP membrane waveguides with different lengths have been fabricated using this mixed resist. A decrease of the propagation loss from 6.6 to 3.3  dB/cm has been demonstrated.

  10. Overview of LHC Beam Loss Measurements

    CERN Document Server

    Dehning, B; Effinger, E; Emery, J; Fadakis, E; Holzer, E B; Jackson, S; Kruk, G; Kurfuerst, C; Marsili, A; Misiowiec, M; Nebot Del Busto, E; Nordt, A; Priebe, A; Roderick, C; Sapinski, M; Zamantzas, C; Grishin, V; Griesmayer, E

    2011-01-01

    The LHC beam loss monitoring system provides measurements with an update rate of 1 Hz and high time resolution data by event triggering. These informations are used for the initiation of beam aborts, fixed displays and the off line analysis. The analysis of fast and localized loss events resulted in the determination of its rate, duration, peak amplitudes, its scaling with intensity, number of bunches and beam energy. The calibration of the secondary shower beam loss signal in respect to the needed beam energy deposition to quench the magnet coil is addressed at 450GeV and 3.5T eV . The adjustment of collimators is checked my measuring the loss pattern and its variation in the collimation regions of the LHC. Loss pattern changes during a fill allow the observation of non typical fill parameters.

  11. Injection Beam Loss and Beam Quality Checks for the LHC

    CERN Document Server

    Kain, Verena; Bartmann, Wolfgang; Bracco, Chiara; Drosdal, Lene; Holzer, Eva; Khasbulatov, Denis; Magnin, Nicolas; Meddahi, Malika; Nordt, Annika; Sapinski, Mariusz; Vogt, Mathias

    2010-01-01

    The quality of the injection into the LHC is monitored by a dedicated software system which acquires and analyses the pulse waveforms from the injection kickers, and measures key beam parameters and compares them with the nominal ones. The beam losses at injection are monitored on many critical devices in the injection regions, together with the longitudinal filling pattern and maximum trajectory offset on the first 100 turns. The paper describes the injection quality check system and the results from LHC beam commissioning, in particular the beam losses measured during injection at the various aperture limits. The results are extrapolated to full intensity and the consequences are discussed

  12. Beam Dynamics and Beam Losses - Circular Machines

    CERN Document Server

    Kain, V

    2016-01-01

    A basic introduction to transverse and longitudinal beam dynamics as well as the most relevant beam loss mechanisms in circular machines will be presented in this lecture. This lecture is intended for physicists and engineers with little or no knowledge of this subject.

  13. Beam Loss Studies for the CERN PS Booster Using FLUKA

    CERN Document Server

    Damjanovic, S; Mikulec, B; Sapinski, M

    2013-01-01

    In view of future upgrade plans, the beam loss monitor (BLM) coverage of the four PS Booster (PSB) rings was reviewed. FLUKA studies at Linac4 injection and PSB extraction energies were performed to simulate the loss patterns. The results of these studies, presented in this paper, have led to the proposal to double the number of beam loss monitors in the PSB.

  14. Detection of Equipment Faults Before Beam Loss

    CERN Document Server

    Galambos, J

    2016-01-01

    High-power hadron accelerators have strict limits on fractional beam loss. In principle, once a high-quality beam is set up in an acceptable state, beam loss should remain steady. However, in practice, there are many trips in operational machines, owing to excessive beam loss. This paper deals with monitoring equipment health to identify precursor signals that indicate an issue with equipment that will lead to unacceptable beam loss. To this end, a variety of equipment and beam signal measurements are described. In particular, several operational examples from the Spallation Neutron Source (SNS) of deteriorating equipment functionality leading to beam loss are reported.

  15. Female Pattern Hair Loss

    Science.gov (United States)

    ... are signs of hormone imbalance, such as excess facial or body hair, a hormone evaluation should be done. Hormonal changes are a common cause of female hair loss. Many women do not realize that hair loss can occur ...

  16. Characterizing and Controlling Beam Losses at the LANSCE Facility

    Energy Technology Data Exchange (ETDEWEB)

    Rybarcyk, Lawrence J. [Los Alamos National Laboratory

    2012-09-12

    The Los Alamos Neutron Science Center (LANSCE) currently provides 100-MeV H{sup +} and 800-MeV H{sup -} beams to several user facilities that have distinct beam requirements, e.g. intensity, micropulse pattern, duty factor, etc. Minimizing beam loss is critical to achieving good performance and reliable operation, but can be challenging in the context of simultaneous multi-beam delivery. This presentation will discuss various aspects related to the observation, characterization and minimization of beam loss associated with normal production beam operations in the linac.

  17. Application of diamond based beam loss monitors

    Energy Technology Data Exchange (ETDEWEB)

    Hempel, Maria [Brandenburgische Technische Univ. Cottbus (Germany); DESY, Zeuthen (Germany); CERN, Geneva (Switzerland); Baer, Tobias [CERN, Geneva (Switzerland); Hamburg Univ. (Germany); Castro Carballo, Elena Maria [DESY, Zeuthen (Germany); Lohmann, Wolfgang [Brandenburgische Technische Univ. Cottbus (Germany); DESY, Zeuthen (Germany); Schmidt, Ruediger [CERN, Geneva (Switzerland)

    2013-07-01

    The LHC has an operational stored energy of 130MJ per beam. Only a small percentage of beam losses in the LHC equipment can damage material or lead to magnet quenches. Therefore, it is important to monitor different types of beam losses, e.g. scattering on residual gas particles, UFOs, collisions and injection losses. A detailed understanding of beam loss mechanisms is necessary to reduce them and ensure save operation. Two different beam loss monitors are installed in the LHC tunnel: ionization chambers and diamond sensors. Ionization chambers trigger a beam dump if beam losses exceed a certain threshold. They have a time resolution of 40um (half LHC turn) which is not sufficient to resolve bunch-by-bunch beam losses. Diamond sensors have a nanosecond time resolution and can therefore detect bunch-by-bunch beam losses. This time resolution allows an analysis of various types of beam losses and an understanding of the mechanisms. For the first time beam loss intensities were measured bunch-by-bunch caused by different origins of losses. Beam loss measurements using diamond sensors will be presented. The results are compared to simulations and good qualitative agreement was found. The potential of diamond sensors for LHC and experiment applications are discussed.

  18. Preservation of beam loss induced quenches, beam lifetime and beam loss measurements with the HERAp beam-loss-monitor system

    Science.gov (United States)

    Wittenburg, Kay

    1994-06-01

    The beam-loss-monitors (BLMs) in the HERA-proton-ring (HERAp) must fulfill the following requirements: They have to measure losses sensitive and fast enough to prevent the superconducting magnets from beam loss induced quenching; the dynamic range of the monitors must exceed several decades in order to measure losses during beam lifetimes of hundreds of hours as well as the much stronger losses that may quench superconducting magnets; they have to be insensitive to the synchrotron radiation of the adjacent electron-ring (HERAe); and their radiation hardness must allow a monitor-lifetime of a few years of HERA operation. These requirements are well satisfied by the HERAp-BLM-System.

  19. Beam Loss Monitors at LHC

    CERN Document Server

    Dehning, B

    2016-01-01

    One of the main functions of the LHC beam loss measurement system is the protection of equipment against damage caused by impacting particles creating secondary showers and their energy dissipation in the matter. Reliability requirements are scaled according to the acceptable consequences and the frequency of particle impact events on equipment. Increasing reliability often leads to more complex systems. The downside of complexity is a reduction of availability; therefore, an optimum has to be found for these conflicting requirements. A detailed review of selected concepts and solutions for the LHC system will be given to show approaches used in various parts of the system from the sensors, signal processing, and software implementations to the requirements for operation and documentation.

  20. Beam Loss and Beam Shape at the LHC Collimators

    CERN Document Server

    Burkart, Florian

    In this master thesis the beam loss and the beam shape at the LHC collimators was measured, analysed, presented and discussed. Beginning with a short introduction of the LHC, the experiments, the supercon- ducting magnet system, the basics on linear beam dynamics and a describtion of the LHC collimation system are given. This is followed by the presentation of the performance of the LHC collimation sys- tem during 2011. A method to convert the Beam Loss Monitor signal in Gy/s to a proton beam loss rate will be introduced. Also the beam lifetime during the proton physics runs in 2011 will be presented and discussed. Finally, the shape of the LHC beams is analysed by using data obtained by scraping the beam at the LHC primary collimators.

  1. Beam Loss Monitors at the ESRF

    CERN Document Server

    Joly, B; Naylor, G A

    2000-01-01

    The European Synchrotron radiation facility is a third generation x-ray source providing x-rays on a continuous basis. As a facility available to external users, the monitoring of radiation caused by the loss of high-energy stored beam is of great concern. A network of beam loss monitors has been installed inside the storage ring tunnel so as to detect and localize the slow loss of electrons during a beam decay. This diagnostic tool allows optimization of beam parameters and physical aperture limits as well as giving useful information on the machine to allow the lifetime to be optimized and defects localized.

  2. Cryogenic Beam Loss Monitoring for the LHC

    CERN Document Server

    Kurfuerst, C; Sapinski, M

    A Beam Loss Monitoring (BLM) system was installed on the outside surface of the LHC magnet cryostats to protect the accelerator equipment from beam losses. The protection is achieved by extracting the beam from the ring in case thresholds imposed on measured radiation levels are exceeded. Close to the interaction regions of the LHC, the present BLM system is sensitive to particle showers generated in the interaction region of the two beams. In the future, with beams of higher energy and brightness resulting in higher luminosity, distinguishing between these interaction products and possible quench-provoking beam losses from the primary proton beams will be challenging. The particle showers measured by the present BLM configuration are partly shielded by the cryostat and the iron yoke of the magnets. The system can hence be optimised by locating beam loss monitors as close as possible to the protected element, i. e. the superconducting coils, inside the cold mass of the magnets in superfluid helium at 1.9 K. T...

  3. Beam losses in heavy ion drivers

    CERN Document Server

    Mustafin, E R; Hofmann, I; Spiller, P J

    2002-01-01

    While beam loss issues have hardly been considered in detail for heavy ion fusion scenarios, recent heavy ion machine developments in different labs (European Organization for Nuclear Research (CERN), Gesellschaft fur Schwerionenforschung (GSI), Institute for Theoretical and Experimental Physics (ITEP), Relativistic Heavy-Ion Collider (RHIC)) have shown the great importance of beam current limitations due to ion losses. Two aspects of beam losses in heavy ion accelerators are theoretically considered: (1) secondary neutron production due to lost ions, and (2) vacuum pressure instability due to charge exchange losses. Calculations are compared and found to be in good agreement with measured data. The application to a Heavy-Ion Driven Inertial Fusion (HIDIF) scenario is discussed. 12 Refs.

  4. Beam Loss Detection at Radiation Source ELBE

    CERN Document Server

    Michel, P; Schurig, R; Langenhagen, H

    2003-01-01

    The Rossendorf superconducting Electron Linac of high Brilliance and low Emittance (ELBE) delivers an 40 MeV, 1 mA cw-beam for different applications such as bremsstrahlung production, electron channelling, free-electron lasers or secondary particle beam generation. In this energy region in case of collisions of the electron beam with the pipe nearly all beam power will be deposited into the pipe material. Therefore a reliable beam loss monitoring is essential for machine protection at ELBE. Different systems basing on photo multipliers, compton diodes and long ionization chambers were studied. The pros and cons of the different systems will be discussed. Ionization chambers based on air-isolated RF cables installed some cm away parallel to the beam line turned out to be the optimal solution. The beam shut-off threshold was adjusted to 1 μC integral charge loss during a 100 ms time interval. Due to the favourable geometry the monitor sensitivity varies less than ±50% along the beam line (di...

  5. Beam Loss Diagnostics Based on Pressure Measurements

    CERN Document Server

    Weinrich, U

    2003-01-01

    The GSI is operating a heavy ion synchrotron, which is currently undergoing an upgrade towards higher beam intensities. It was discovered that beam losses induce a significant pressure increase in the vacuum system. In order to detect the time constants of the pressure increase and decrease, fast total pressure measurements were put into operation. With the recently installed partial pressure diagnostics it is also possible to follow up which types of molecules are released. The presentation will focus on the different techniques applied as well as on some measurement results. The potential and difficulties of this diagnostic tool will also be discussed.

  6. Analysis of beam loss induced abort kicker instability

    Energy Technology Data Exchange (ETDEWEB)

    Zhang W.; Sandberg, J.; Ahrens, L.; Fischer, W.; Hahn, H.; Mi, J.; Pai, C.; Tan, Y.

    2012-05-20

    Through more than a decade of operation, we have noticed the phenomena of beam loss induced kicker instability in the RHIC beam abort systems. In this study, we analyze the short term beam loss before abort kicker pre-fire events and operation conditions before capacitor failures. Beam loss has caused capacitor failures and elevated radiation level concentrated at failed end of capacitor has been observed. We are interested in beam loss induced radiation and heat dissipation in large oil filled capacitors and beam triggered thyratron conduction. We hope the analysis result would lead to better protection of the abort systems and improved stability of the RHIC operation.

  7. Electron Beam Lithography for nano-patterning

    DEFF Research Database (Denmark)

    Greibe, Tine; Anhøj, Thomas Aarøe; Khomtchenko, Elena;

    2014-01-01

    Electron beam lithography is a versatile tool for fabrication of nano-sized patterns. The patterns are generated by scanning a focused beam of high-energy electrons onto a substrate coated with a thin layer of electron-sensitive polymer (resist), i.e. by directly writing custom-made patterns...... in a polymer. Electron beam lithography is a suitable method for nano-sized production, research, or development of semiconductor components on a low-volume level. Here, we present electron beam lithography available at DTU Danchip. We expertize a JEOL 9500FZ with electrons accelerated to an energy of 100ke......V and focused to a beam spot size down to ~5nm. The electron beam can scan across the substrate with a speed of 100MHz and can write areas of 1mm x 1mm without stitching. In order to ensure high-precision patterning, the beam position on the substrate is controlled by a two-stage deflector system and substrates...

  8. Classifications of patterned hair loss: a review

    Directory of Open Access Journals (Sweden)

    Mrinal Gupta

    2016-01-01

    Full Text Available Patterned hair loss is the most common cause of hair loss seen in both the sexes after puberty. Numerous classification systems have been proposed by various researchers for grading purposes. These systems vary from the simpler systems based on recession of the hairline to the more advanced multifactorial systems based on the morphological and dynamic parameters that affect the scalp and the hair itself. Most of these preexisting systems have certain limitations. Currently, the Hamilton-Norwood classification system for males and the Ludwig system for females are most commonly used to describe patterns of hair loss. In this article, we review the various classification systems for patterned hair loss in both the sexes. Relevant articles were identified through searches of MEDLINE and EMBASE. Search terms included but were not limited to androgenic alopecia classification, patterned hair loss classification, male pattern baldness classification, and female pattern hair loss classification. Further publications were identified from the reference lists of the reviewed articles.

  9. Beam Loss Control for the Fermilab Main Injector

    CERN Document Server

    Brown, Bruce C

    2013-01-01

    From 2005 through 2012, the Fermilab Main Injector provided intense beams of 120 GeV protons to produce neutrino beams and antiprotons. Hardware improvements in conjunction with improved diagnostics allowed the system to reach sustained operation at 400 kW beam power. Losses were at or near the 8 GeV injection energy where 95% beam transmission results in about 1.5 kW of beam loss. By minimizing and localizing loss, residual radiation levels fell while beam power was doubled. Lost beam was directed to either the collimation system or to the beam abort. Critical apertures were increased while improved instrumentation allowed optimal use of available apertures. We will summarize the impact of various loss control tools and the status and trends in residual radiation in the Main Injector.

  10. Simulation and optimization of beam losses during continuous transfer extraction at the CERN Proton Synchrotron

    CERN Document Server

    Garcia, J B

    2011-01-01

    The proton beams used for the fixed target physics at the Super Proton Synchrotron (SPS) are extracted from the Proton Synchrotron ( PS) by a multiturn technique called continuous transfer (CT). During the CT extraction, large losses are observed in locations where the machine aperture should be large enough to accommodate the circulating beam. This limits the maximum intensity deliverable due to the induced stray radiation outside the PS tunnel. Scattered particles from the interaction with the electrostatic septum are identified as the possible source of these losses. This article presents a detailed study aiming to understand the origin of losses and propose possible cures. The simulations could reproduce accurately the beam loss pattern measured in real machine operation and determine the beam shaving, intrinsic to the extraction process, as the cause for the unexpected losses. Since these losses are unavoidable, the proposed solution implies a new optics scheme displacing the losses to a region with bett...

  11. Fermilab main injector: High intensity operation and beam loss control

    Science.gov (United States)

    Brown, Bruce C.; Adamson, Philip; Capista, David; Chou, Weiren; Kourbanis, Ioanis; Morris, Denton K.; Seiya, Kiyomi; Wu, Guan Hong; Yang, Ming-Jen

    2013-07-01

    From 2005 through 2012, the Fermilab Main Injector provided intense beams of 120 GeV protons to produce neutrino beams and antiprotons. Hardware improvements in conjunction with improved diagnostics allowed the system to reach sustained operation at 400 kW beam power. Transmission was very high except for beam lost at or near the 8 GeV injection energy where 95% beam transmission results in about 1.5 kW of beam loss. By minimizing and localizing loss, residual radiation levels fell while beam power was doubled. Lost beam was directed to either the collimation system or to the beam abort. Critical apertures were increased while improved instrumentation allowed optimal use of available apertures. We will summarize the improvements required to achieve high intensity, the impact of various loss control tools and the status and trends in residual radiation in the Main Injector.

  12. Luminosity Loss due to Beam Distortion and the Beam-Beam Instability

    CERN Document Server

    Wu, Juhao; Raubenheimer, Tor O; Seryi, Andrei; Sramek, Christopher K

    2005-01-01

    In a linear collider, sources of emittance dilution such as transverse wakefields or dispersive errors will couple the vertical phase space to the longitudinal position within the beam (the so-called ‘banana effect'). When the Intersection Point (IP) disruption parameter is large, these beam distortions will be amplified by a single bunch kink instability which will lead to luminosity loss. We study this phenomena both analytically using linear theory and via numerical simulation. In particular, we examine the dependence of the luminosity loss on the wavelength of the beam distortions and the disruption parameter. This analysis may prove useful when optimizing the vertical disruption parameter for luminosity operation with given beam distortions.

  13. Measurements of Beam Ion Loss from the Compact Helical System

    Energy Technology Data Exchange (ETDEWEB)

    D. S. Darrow, M. Isobe, Takashi Kondo, M. Sasao, and the CHS Group National Institute for Fusion Science, Toki, Gifu, Japan

    2010-02-03

    Beam ion loss from the Compact Helical System (CHS) has been measured with a scintillator-type probe. The total loss to the probe, and the pitch angle and gyroradius distributions of that loss, have been measured as various plasma parameters were scanned. Three classes of beam ion loss were observed at the probe position: passing ions with pitch angles within 10o of those of transition orbits, ions on transition orbits, and ions on trapped orbits, typically 15o or more from transition orbits. Some orbit calculations in this geometry have been performed in order to understand the characteristics of the loss. Simulation of the detector signal based upon the following of orbits from realistic beam deposition profiles is not able to reproduce the pitch angle distribution of the losses measured. Consequently it is inferred that internal plasma processes, whether magnetohydrodynamic modes, radial electric fields, or plasma turbulence, move previously confined beam ions to transition orbits, resulting in their loss.

  14. Cavity loss factors for non-ultrarelativistic beams

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S.S.

    1998-12-31

    Cavity loss factors can be easily computed for ultrarelativistic beams using time-domain codes like MAFIA or ABCI. However, for non-ultrarelativistic beams the problem is more complicated because of difficulties with its numerical formulation in the time domain. The authors calculate the loss factors of a non-relativistic bunch and compare results with the relativistic case.

  15. Cavity Loss Factors For Non-Ultrarelativistic Beams

    CERN Document Server

    Kurennoy, S S

    1998-01-01

    Cavity loss factors can be easily computed for ultrarelativistic beams using time-domain codes like MAFIA or ABCI. However, for non-ultrarelativistic beams the problem is more complicated because of difficulties with its numerical formulation in the time domain. We calculate the loss factors of a non-ultrarelativistic bunch and compare results with the relativistic case.

  16. LHC Beam Loss Monitoring System Verification Applications

    CERN Document Server

    Dehning, B; Zamantzas, C; Jackson, S

    2011-01-01

    The LHC Beam Loss Mon­i­tor­ing (BLM) sys­tem is one of the most com­plex in­stru­men­ta­tion sys­tems de­ployed in the LHC. In ad­di­tion to protecting the col­lid­er, the sys­tem also needs to pro­vide a means of di­ag­nos­ing ma­chine faults and de­liv­er a feed­back of loss­es to the control room as well as to sev­er­al sys­tems for their setup and analysis. It has to trans­mit and pro­cess sig­nals from al­most 4’000 mon­i­tors, and has near­ly 3 mil­lion con­fig­urable pa­ram­e­ters. The system was de­signed with re­li­a­bil­i­ty and avail­abil­i­ty in mind. The spec­i­fied op­er­a­tion and the fail-safe­ty stan­dards must be guar­an­teed for the sys­tem to per­form its func­tion in pre­vent­ing su­per­con­duc­tive mag­net de­struc­tion caused by par­ti­cle flux. Main­tain­ing the ex­pect­ed re­li­a­bil­i­ty re­quires ex­ten­sive test­ing and ver­i­fi­ca­tion. In this paper we re­port our most re­cent ad­di­t...

  17. Beam loss studies at the ANKA storage ring

    Energy Technology Data Exchange (ETDEWEB)

    Hertle, Edmund; Smale, Nigel; Goetsch, Tobias; Mueller, Anke-Susanne; Wegh, Frans; Worms, Kai [Karlsruher Institut fuer Technologie (Germany)

    2013-07-01

    The real time study and the post mortem analysis of beam loss are powerful tools for the optimization of a storage ring's performance. It allows, for example, a fast identification of failing hardware components or can be used to improve the beam lifetime by a reduction of the losses. This needs a sophisticated beam loss monitor system with appropriate spatial and temporal resolution. This presentation gives an overview of the loss monitor system under study at the ANKA synchrotron radiation facility of the Karlsruhe Institute of Technology.

  18. Beam Loss Monitors for NSLS-II Storage Ring

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, S.L.; Cameron, P.

    2011-03-28

    The shielding for the NSLS-II storage ring will provide adequate protection for the full injected beam losses in two cells of the ring around the injection point, but the remainder of the ring is shielded for lower losses of <10% top-off injection beam current. This will require a system to insure that beam losses do not exceed levels for a period of time that could cause excessive radiation exposure outside the shield walls. This beam Loss Control and Monitoring system will have beam loss monitors that will measure where the beam charge is lost around the ring, to warn operators if losses approach the design limits. To measure the charge loss quantitatively, we propose measuring the electron component of the shower as beam electrons hit the vacuum chamber (VC) wall. This will be done using the Cerenkov light as electrons transit ultra-pure fused silica rods placed close to the inner edge of the VC. The entire length of the rod will collect light from the electrons of the spread out shower resulting from the small glancing angle of the lost beam particles to the VC wall. The design and measurements results of the prototype Cerenkov BLM will be presented.

  19. Beam loss monitors comparison at the CERN Proton Synchrotron

    CERN Document Server

    Gilardoni, S S; Effinger, E; Gil-Flores, J; Wienands, U

    2011-01-01

    CERN is planning the renovation and upgrade of the beam loss detection system for the Proton Synchrotron (PS). Improved performance in speed–to be able to monitor beam loss on a bunch-by-bunch basis–and in longterm stability–to reduce or avoid the need for periodic calibration–are aimed for. To select the most suitable technology, different detectors were benchmarked in the machine with respect to the same beam loss. The characteristics of the different detectors, the results of the measurement campaign and their suitability as future monitors for the PS are presented.

  20. Monitoring system experiments on beam loss at SSRF injector

    Science.gov (United States)

    Cai, Jun; Xia, XiaoBin; Xu, XunJiang; Liu, Xin; Xu, JiaQiang; Wang, GuangHong; Zeng, Ming

    2011-12-01

    Experiments on beam loss by using beam loss monitoring (BLM) system were carried out at Shanghai Synchrotron Radiation Facility (SSRF) injector. This system used highly sensitive and current-integrated Si-photodiode detectors and an Ethernet data acquisition (DAQ) system. The experimental results demonstrate that the Si-photodiode detectors are a useful tool that provides dynamic information on beam loss and investigates problems of machine operation. It also shows that the Si-photodiode BLM system is suitable for pulse-radiation of high-energy accelerators.

  1. Monitoring system experiments on beam loss at SSRF injector

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Experiments on beam loss by using beam loss monitoring (BLM) system were carried out at Shanghai Synchrotron Radiation Facility (SSRF) injector. This system used highly sensitive and current-integrated Si-photodiode detectors and an Ethernet data acquisition (DAQ) system. The experimental results demonstrate that the Si-photodiode detectors are a useful tool that provides dynamic information on beam loss and investigates problems of machine operation. It also shows that the Si-photodiode BLM system is suitable for pulse-radiation of high-energy accelerators.

  2. Beam Loss Estimates and Control for the BNL Neutrino Facility

    CERN Document Server

    Weng, Wu-Tsung; Raparia, Deepak; Tsoupas, Nicholaos; Wei, Jie; Yung Lee, Yong; Zhang, S Y

    2005-01-01

    BNL plans to upgrade the AGS proton beam from the current 0.14 MW to higher than 1.0 MW for a very long baseline neutrino oscillation experiment. This increase in beam power is mainly due to the faster repetition rate of the AGS by a new 1.5 GeV superconductiong linac as injector, replacing the existing booster. The requirement for low beam loss is very important both to protect the beam component, and to make the hands-on maintenance possible. In this report, the design considerations for achieving high intensity and low loss will be presented. We start by specifying the beam loss limit at every physical process followed by the proper design and parameters for realising the required goals. The process considered in this paper include the emittance growth in the linac, the H-

  3. CCD based beam loss monitor for ion accelerators

    Science.gov (United States)

    Belousov, A.; Mustafin, E.; Ensinger, W.

    2014-04-01

    Beam loss monitoring is an important aspect of proper accelerator functioning. There is a variety of existing solutions, but each has its own disadvantages, e.g. unsuitable dynamic range or time resolution, high cost, or short lifetime. Therefore, new options are looked for. This paper shows a method of application of a charge-coupled device (CCD) video camera as a beam loss monitor (BLM) for ion beam accelerators. The system was tested with a 500 MeV/u N+7 ion beam interacting with an aluminum target. The algorithms of camera signal processing with LabView based code and beam loss measurement are explained. Limits of applicability of this monitor system are discussed.

  4. FLUKA simulations for the optimization of the Beam Loss Monitors

    CERN Document Server

    Brugger, M; Ferrari, A; Magistris, M; Santana-Leitner, M; Vlachoudis, V; CERN. Geneva. AB Department

    2006-01-01

    The collimation system in the beam cleaning insertion IR7 of the Large Hadron Collider (LHC) is expected to clean the primary halo and the secondary radiation of a beam with unprecedented energy and intensity. Accidental beam losses can therefore entail severe consequences to the hardware of the machine. Thus, protection mechanisms, e.g. beam abort, must be instantaneously triggered by a set of Beam Loss Monitors (BLM's). The readings in the BLM's couple the losses from various collimators, thus rendering the identification of any faulty unit rather complex. In the present study the detailed geometry of IR7 is upgraded with the insertion of the BLM's, and the Monte Carlo FLUKA transport code is used to estimate the individual contribution of every collimator to the showers detected in each BLM.

  5. Beam loss mechanisms in relativistic heavy-ion colliders

    CERN Document Server

    Bruce, Roderik; Gilardoni, S; Wallén, E

    2009-01-01

    The Large Hadron Collider (LHC), the largest particle accelerator ever built, is presently under commissioning at the European Organization for Nuclear Research (CERN). It will collide beams of protons, and later Pb82+ ions, at ultrarelativistic energies. Because of its unprecedented energy, the operation of the LHC with heavy ions will present beam physics challenges not encountered in previous colliders. Beam loss processes that are harmless in the presently largest operational heavy-ion collider, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory, risk to cause quenches of superconducting magnets in the LHC. Interactions between colliding beams of ultrarelativistic heavy ions, or between beam ions and collimators, give rise to nuclear fragmentation. The resulting isotopes could have a charge-to-mass ratio different from the main beam and therefore follow dispersive orbits until they are lost. Depending on the machine conditions and the ion species, these losses could occur in loca...

  6. Dependence of bunch energy loss in cavities on beam velocity

    Science.gov (United States)

    Kurennoy, Sergey S.

    1999-03-01

    Beam energy loss in a cavity can be easily computed for a relativistic bunch using time-domain codes like MAFIA or ABCI. However, for nonrelativistic beams the problem is more complicated because of difficulties with its numerical formulation in the time domain. We calculate the cavity loss factors for a bunch in frequency domain as a function of its velocity and compare results with the relativistic case.

  7. A Versatile Beam Loss Monitoring System for CLIC

    CERN Document Server

    Kastriotou, Maria; Farabolini, Wilfrid; Holzer, Eva Barbara; Nebot Del Busto, Eduardo; Tecker, Frank; Welsch, Carsten

    2016-01-01

    The design of a potential CLIC beam loss monitoring (BLM) system presents multiple challenges. To successfully cover the 48 km of beamline, ionisation chambers and optical fibre BLMs are under investigation. The former fulfils all CLIC requirements but would need more than 40000 monitors to protect the whole facility. For the latter, the capability of reconstructing the original loss position with a multi-bunch beam pulse and multiple loss locations still needs to be quantified. Two main sources of background for beam loss measurements are identified for CLIC. The two-beam accelerator scheme introduces so-called crosstalk, i.e. detection of losses originating in one beam line by the monitors protecting the other. Moreover, electrons emitted from the inner surface of RF cavities and boosted by the high RF gradients may produce signals in neighbouring BLMs, limiting their ability to detect real beam losses. This contribution presents the results of dedicated experiments performed in the CLIC Test Facility to qu...

  8. Parasitic mode losses versus signal sensitivity in beam position monitors

    Science.gov (United States)

    Denard, J. C.; Bane, K. L.; Bijleveld, J.; Hutton, A. M.; Pellegrin, J. I.; Rivkin, L.; Wang, P.; Weaver, J. N.

    1985-04-01

    A beam position monitor (BPM) for a storage or damping ring may be subject to heating problems due to the parasitic mode (PM) losses, beam interception and synchrotron radiation interception. In addition, high PM losses can cause beam instabilities under some conditions. Recessing and/or masking the BPM may increase the PM losses in the process of solving the latter two problems. Three complementary methods for estimating the PM losses and for improving the design of a stripline directional coupler type of BPM: bench measurements, computer modeling (TBCI), and an equivalent circuit representation are presented. These methods lead to a decrease in PM losses without significant reduction in output signal for the north Stanford Linear Collider (SLC) damping ring BPMs.

  9. Beam loss detection system in the arcs of the LHC

    Science.gov (United States)

    Arauzo, A.; Bovet, C.

    2000-11-01

    Over the whole circumference of the LHC, Beam Loss Monitors (BLM) will be needed for a continuous surveillance of fast and slow beam losses. In this paper, the location of the BLMs set outside the magnet cryostats in the arcs is proposed. In order to know the number of protons lost on the beam screen, the sensitivity of each BLM has been computed using the program GEANT 3.21, which generates the shower inside the cryostat. The material and the magnetic fields have been described thoroughly in 3-D and the simulation results show the best locations for 6 BLMs needed around each quadrupole. The number of minimum ionizing particles received for each lost proton serves to define local thresholds to dump the beam when the losses are menacing to quench a magnet.

  10. Beam Loss Detection System in the Arcs of the LHC

    CERN Document Server

    Arauzo-Garcia, A

    2000-01-01

    Over the whole circumference of the LHC, Beam Loss Monitors (BLM) will be needed for a continuous surveillance of fast and slow beam losses. In this paper, the location of the BLMs set outside the magnet cryostats in the arcs is proposed. In order to know the number of protons lost on the beam screen, the sensitivity of each BLM has been computed using the program GEANT 3.21, which generates the shower inside the cryostat. The material and the magnetic fields have been described thoroughly in 3-D and the simulation results show the best locations for 6 BLMs needed around each quadrupole. The number of minimum ionizing particles received for each lost proton serves to define local thresholds to dump the beam when the losses are menacing to quench a magnet

  11. Beam loss control in the LINAC4 design

    CERN Document Server

    Stovall, J; Crandall, K

    2010-01-01

    The Linac4 DTL reference design has been modified to reduce the power consumption in tank 1 by modifying the accelerating field and phase law. In addition we have adopted an FFDD focusing lattice throughout to minimize expected losses resulting from alignment errors. We have observed, however, that this design suffers from decreasing transverse acceptance and a sensitivity to misalignments that causes any expected beam loss to occcur at the high energy end of the DTL. In this note we investigate two solutions to increase the acceptance, decrease its sensitivity to misalignments and eliminate the potential for a beam-loss “bottleneck” at 50 MeV.

  12. Simulations of Neutral Beam Ion Ripple Loss on EAST

    Institute of Scientific and Technical Information of China (English)

    李吉波; 丁斯晔; 吴斌; 胡纯栋

    2012-01-01

    Predictions on the ripple loss of neutral beam fast ions on EAST are investigated with a guiding center code, including both ripple and collisional effects. A 6% to 16% loss of neutral beam ions is predicted for typical EAST experiments, and a synergistic enhancement of fast ion loss is found for toroidal field (TF) ripples with collisions. The lost ions are strongly localized and will cause a maximum heat load of - 0.05 MW/m^2 on the first wall.

  13. Beam Loss Calibration Studies for High Energy Proton Accelerators

    CERN Document Server

    Stockner, M

    2007-01-01

    CERN's Large Hadron Collider (LHC) is a proton collider with injection energy of 450 GeV and collision energy of 7 TeV. Superconducting magnets keep the particles circulating in two counter rotating beams, which cross each other at the Interaction Points (IP). Those complex magnets have been designed to contain both beams in one yoke within a cryostat. An unprecedented amount of energy will be stored in the circulating beams and in the magnet system. The LHC outperforms other existing accelerators in its maximum beam energy by a factor of 7 and in its beam intensity by a factor of 23. Even a loss of a small fraction of the beam particles may cause the transition from the superconducting to the normal conducting state of the coil or cause physical damage to machine components. The unique combination of these extreme beam parameters and the highly advanced superconducting technology has the consequence that the LHC needs a more efficient beam cleaning and beam loss measurement system than previous accelerators....

  14. Application of diamond based beam loss monitors at LHC

    Energy Technology Data Exchange (ETDEWEB)

    Hempel, Maria

    2013-04-15

    The Large Hadron Collider (LHC) was conceived in the 1980s and started the operation in 2008. It needed more than 20 years to plan and construct this accelerator and its experiments. Four main experiments are located around the ring, Compact Muon Solenoid (CMS), A Toroidal LHC Apparatus(ATLAS), A Large Ion Collider Experiment (ALICE) and LHC beauty (LHCb). Two beams that traveling in opposite direction in the LHC tunnel, collide in each of the experiments to study the questions: ''What is mass?'', ''What is the universe made of?'' and ''Why is there no antimatter?''. The four experiments take data of the collision products and try to answer the fundamental questions of physics. The two larger detectors, CMS and ATLAS, are looking for the Higgs boson to study the electroweak symmetry breaking. Both detectors were built with contrasting concepts to exclude potential error sources and to rea rm the results. The smaller experiment LHCb studies the matter-antimatter asymmetry with a focus of the beauty quark. Another smaller experiment is ALICE that studies the conditions right after the Big Bang by colliding heavy ions. The navigation of the beams is done by over 10000 magnets and each beam has a stored energy of 362MJ which correspond to the kinetic energy of a train like the TGV travelling of 150 km/h. Only a small percentage of that energy can damage the material in the LHC ring or the magnets. This would mean a repair time of months or years, without taking any data. To avoid such a scenario, it is important to monitor the beam condition and measure the amount of losses of the beam. Such losses can for example happen due to dust particles in the vacuum chambers or due to deviations of the beam parameters. Several systems called beam loss monitors (BLMs) can measure beam losses. This thesis concentrates on two of them, ionization chambers and diamond detectors. Over 3600 ionization chambers are installed in

  15. Beam studies for the Proton Improvement Plan (PIP) -- reducing beam loss at the Fermilab Booster

    CERN Document Server

    Seiya, K; Johnson, D E; Kapin, V V; Pellico, W A; Tan, C Y; Tesarek, R J

    2015-01-01

    The Fermilab Booster is being upgraded under the Proton Improvement Plan (PIP) to be capable of providing a proton flux of $2.25^{17}$ protons per hour. The intensity per cycle will remain at the present operational $4.3^{12}$ protons per pulse, however the Booster beam cycle rate is going to be increased from 7.5 Hz to 15 Hz. One of the biggest challenges is to maintain the present beam loss power while the doubling the beam flux. Under PIP, there has been a large effort in beam studies and simulations to better understand the mechanisms of the beam loss. The goal is to reduce it by half by correcting and controlling the beam dynamics and by improving operational systems through hardware upgrades. This paper is going to present the recent beam study results and status of the Booster operations.

  16. Beam Loss Studies for Rare Isotope Driver Linacs Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Wangler, T P; Kurennoy, S S; Billen, J H; Crandall, K R; Qiang, J; Ryne, R D; Mustapha, B; Ostroumov, P; Zhao, Q; York, and R. C.

    2008-03-26

    The Fortran 90 RIAPMTQ/IMPACT code package is a pair of linked beam-dynamics simulation codes that have been developed for end-to-end computer simulations of multiple-charge-state heavy-ion linacs for future exotic-beam facilities. These codes have multiple charge-state capability, and include space-charge forces. The simulations can extend from the low-energy beam-transport line after an ECR ion source to the end of the linac. The work has been performed by a collaboration including LANL, LBNL, ANL, and MSU. The code RIAPMTQ simulates the linac front-end beam dynamics including the LEBT, RFQ, and MEBT. The code IMPACT simulates the beam dynamics of the main superconducting linac. The codes have been benchmarked for rms beam properties against previously existing codes at ANL and MSU. The codes allow high-statistics runs on parallel supercomputing platforms, particularly at NERSC at LBNL, for studies of beam losses. The codes also run on desktop PC computers for low-statistics work. The code package is described in more detail in a recent publication [1] in the Proceedings of PAC07 (2007 US Particle Accelerator Conference). In this report we describe the main activities for the FY07 beam-loss studies project using this code package.

  17. Monte Carlo Simulations of Beam Losses in the Test Beam Line of CTF3

    CERN Document Server

    Nebot Del Busto, E; Branger, E; Holzer, E B; Doebert, S; Lillestol, R L; Welsch, C P

    2013-01-01

    The Test Beam Line (TBL) of the CLIC Test Facility 3 (CTF3) aims to validate the drive beam deceleration concept of CLIC, in which the RF power requested to boost particles to multi-TeV energies is obtained via deceleration of a high current and low energy drive beam (DB). Despite a TBL beam energy (150-80 MeV) significantly lower than the minimum nominal energy of the CLIC DB (250 MeV), the pulse time structure of the TBL provides the opportunity to measure beam losses with CLIC-like DB timing conditions. In this contribution, a simulation study on the detection of beam losses along the TBL for the commissioning of the recently installed beam loss monitoring system is presented. The most likely loss locations during stable beam conditions are studied by considering the beam envelope defined by the FODO lattice as well as the emittance growth due to the deceleration process. Moreover, the optimization of potential detector locations is discussed. Several factors are considered, namely: the distance to the bea...

  18. Loss management in the beta-beam decay ring

    CERN Document Server

    Chancé, Antoine

    2006-01-01

    The aim of the beta-beams is to produce pure electron neutrino and anti-neutrino highly energetic beams, coming from β-decay of the 18Ne10+ and 6He2+, both at γ = 100, directed towards experimental halls situated in the Fréjus tunnel [1], [2]. The high intensity ion beams are stored in a ring, until the ions decay. Consequently, all the injected particles will be lost anywhere around the ring generating a high level of irradiation. In order to keep a constant neutrino flux, the losses due to the decay of the radioactive ions are compensated with regular injections. The new ion beam is then merged with the stored beam with a specific RF program [3]. We have to consider two sources of losses: – The β-decay products: their magnetic rigidity being different from the reference one, they are bent differently and lost. – The losses during the injection merging process. The first one needs a particular ring design in order to insert appropriate beam stoppers at the right place. The second one needs a specific...

  19. 2014 Joint International Accelerator School: Beam Loss and Accelerator Protection

    CERN Document Server

    JAS - Joint US-CERN-Japan-Russia Accelerator School

    2016-01-01

    Many particle accelerators operate with very high beam power and very high energy stored in particle beams as well as in magnet systems. In the future, the beam power in high intensity accelerators will further increase. The protection of the accelerator equipment from the consequences of uncontrolled release of the energy is essential. This was the motivation for organizing a first school on beam losses and accelerator protection (in general referred to as machine protection). During the school the methods and technologies to identify, mitigate, monitor and manage the technical risks associated with the operation of accelerators with high-power beams or subsystems with large stored energy were presented. At the completion of the school the participants should have been able to understand the physical phenomena that can damage machine subsystems or interrupt operations and to analyze an accelerator facility to produce a register of technical risks and the corresponding risk mitigation and management strategie...

  20. SPS transverse beam scraping and LHC injection losses

    CERN Document Server

    Drosdal, L; Bartmann, W; Bracco, C; Cornelis, K; Goddard, B; Meddahi, M; Veyrunes, E

    2012-01-01

    Machine protection sets strict requirements for the quality of the injected beam, in particular in the transverse plane. Losses at aperture restrictions and protection elements have to be kept at a minimum. Particles in the beam tails are lost at the tight transfer line collimators and can trigger the LHC beam abort system. These particles have to be removed by scrapers in the vertical and horizontal plane in the SPS. Scraping has become vital for high intensity LHC operation. This paper shows the dependence of injection quality on the SPS scraping and discusses an improved scraper setting up strategy for better reproducibility with the current scraper system.

  1. Cherenkov Fibers for Beam Loss Monitoring at the CLIC Two Beam Module

    CERN Document Server

    van Hoorne, Jacobus Willem; Holzer, E B

    The Compact Linear Collider (CLIC) study is a feasibility study aiming at a nominal center of mass energy of 3TeV and is based on normal conducting travelling-wave accelerating structures, operating at very high field gradients of 100 MV/m. Such high fields require high peak power and hence a novel power source, the CLIC two beam system, has been developed, in which a high intensity, low energy drive beam (DB) supplies energy to a high energy, low intensity main beam (MB). At the Two Beam Modules (TBM), which compose the 2x21km long CLIC main linac, a protection against beam losses resulting from badly controlled beams is necessary and particularly challenging, since the beam power of both main beam (14 MW) and drive beam (70 MW) is impressive. To avoid operational downtimes and severe damages to machine components, a general Machine Protection System (MPS) scheme has been developed. The Beam Loss Monitoring (BLM) system is a key element of the CLIC machine protection system. Its main role will be to detect p...

  2. Simulation and Measurements of Beam Losses on LHC Collimators During Beam Abort Failures

    CERN Document Server

    Lari, L; Bruce, R; Goddard, B; Redaelli, S; Salvachua, B; Valentino, G; Faus-Golfe, A

    2013-01-01

    One of the main purposes of tracking simulations for collimation studies is to produce loss maps along the LHC ring, in order to identify the level of local beam losses during nominal and abnormal operation scenarios. The SixTrack program is the standard tracking tool used at CERN to perform these studies. Recently, it was expanded in order to evaluate the proton load on different collimators in case of fast beam failures. Simulations are compared with beam measurements at 4 TeV. Combined failures are assumed which provide worst-case scenarios of the load on tungsten tertiary collimators.

  3. Beam Loss Monitoring for Run 2 of the LHC

    CERN Document Server

    Kalliokoski, Matti; Dehning, Bernd; Domingues Sousa, Fernando; Effinger, Ewald; Emery, Jonathan; Grishin, Viatcheslav; Holzer, Eva Barbara; Jackson, Stephen; Kolad, Blazej; Nebot Del Busto, Eduardo; Picha, Ondrej; Roderick, Chris; Sapinski, Mariusz; Sobieszek, Marcin; Zamantzas, Christos

    2015-01-01

    The Beam Loss Monitoring (BLM) system of the LHC consists of over 3600 ionization chambers. The main task of the system is to prevent the superconducting magnets from quenching and protect the machine components from damage, as a result of critical beam losses. The BLM system therefore requests a beam abort when the measured dose in the chambers exceeds a threshold value. During Long Shutdown 1 (LS1) a series of modifications were made to the system. Based on the experience from Run 1 and from improved simulation models, all the threshold settings were revised, and modified where required. This was done to improve the machine safety at 7 TeV, and to reduce beam abort requests when neither a magnet quench or damage to machine components is expected. In addition to the updates of the threshold values, about 800 monitors were relocated. This improves the response to unforeseen beam losses in the millisecond time scale due to micron size dust particles present in the vacuum chamber. This contribution will discuss...

  4. Update on beam loss monitoring at CTF3 for CLIC

    CERN Document Server

    Devlin, L J; Effinger, E; Holzer, E B; del Busto, E N; Mallows, S; Branger, E

    2013-01-01

    The primary role of the beam loss monitoring (BLM) system for the compact linear collider (CLIC) study is to work within the machine protection system. Due to the size of the CLIC facility, a BLM that covers large distances along the beam line is highly desirable, in particular for the CLIC drive beam decelerators, which would alternatively require some ~40,000 localised monitors. Therefore, an optical fibre BLM system is currently under investigation which can cover large sections of beam line at a time. A multimode fibre has been installed along the Test Beam Line at the CLIC test facility (CTF3) where the detection principle is based on the production of Cherenkov photons within the fibre resulting from beam loss and their subsequent transport along the fibre where they are then detected at the fibre ends using silicon photomultipliers. Several additional monitors including ACEMs, PEP-II and diamond detectors have also been installed. In this contribution the first results from the BLMs are presented, comp...

  5. The LEP RF Trip and Beam Loss Diagnostics System

    CERN Document Server

    Arnaudon, L; Beetham, G; Ciapala, Edmond; Juillard, J C; Olsen, R

    2002-01-01

    During the last years of operation the number of operationally independent RF stations distributed around LEP reached a total of 40. A serious difficulty when running at high energy and high beam intensities was to establish cause and effect in beam loss situations, where the trip of any single RF station would result in beam loss, rapidly producing further multiple RF station trips. For the last year of operation a fast post-mortem diagnostics system was developed to allow precise time-stamping of RF unit trips and beam intensity changes. The system was based on eight local DSP controlled fast acquisition and event recording units, one in each RF sector, connected to critical RF control signals and fast beam intensity monitors and synchronised by GPS. The acquisition units were armed and synchronised at the start of each fill. At the end of the fill the local time-stamped RF trip and beam intensity change history tables were recovered, events ordered and the results stored in a database for subsequent analys...

  6. Tracking Simulation for Beam Loss Studies with Application to FCC

    CERN Document Server

    Boscolo, M

    2015-01-01

    We present first results on FCC-ee beam losses using a tracking simulation tool originally developed and successfully applied to Flav or Factories designs. After a brief description of the tool, we discuss first results obtained for FCC-ee at top energy, both for the Touschek effect and radiative Bhabha scattering.

  7. The LHC beam loss monitoring system's data acquisition card

    CERN Document Server

    Effinger, E; Emery, J; Ferioli, G; Gauglio, G; Zamantzas, C

    2007-01-01

    The beam loss monitoring (BLM) system [1] of the LHC is one of the most critical elements for the protection of the LHC. It must prevent the super conducting magnets from quenches and the machine components from damages, caused by beam losses. Ionization chambers and secondary emission based beam loss detectors are used on several locations around the ring. The sensors are producing a signal current, which is related to the losses. This current will be measured by a tunnel electronic, which acquires, digitizes and transmits the data via an optical link to the surface electronic. The so called threshold comparator (TC) [2] collects, analyzes and compares the data with threshold table. It also gives a dump signal through the combiner card to the beam inter lock system (BIC). The usage of the system, for protection and tuning of the LHC and the scale of the LHC, imposed exceptional specification of the dynamic range and radiation tolerance. The input current dynamic range should allow measurements between 10pA a...

  8. Real-Time Beam Loss Monitor Display Using FPGA Technology

    CERN Document Server

    North, Matt R W

    2005-01-01

    This paper outlines the design of a Real-time Beam Loss Monitor Display for the ISIS Synchrotron based at Rutherford Appleton Laboratory (Oxon, UK). Beam loss is monitored using 39 argon filled ionisation chambers positioned around the synchrotron, the levels of which are sampled four times in each cycle. The new BLM display acquires the signals and displays four histograms, each relating to an individual sample period; the data acquisition and signal processing required to build the display fields are completed within each machine cycle (50 Hz). Attributes of the new system include setting limits for individual monitors; displaying over-limit detection, and freezing the display field when a beam trip has occurred. The design is based around a reconfigurable Field Programmable Gate Array, interfacing to a desktop monitor via the VGA standard. Results gained using simulated monitor signals have proven the system.

  9. RF Cavity Induced Sensitivity Limitations on Beam Loss Monitors

    Science.gov (United States)

    Kastriotou, M.; Degiovanni, A.; Sousa, F. S. Domingues; Effinger, E.; Holzer, E. B.; Quirante, J. L. Navarro; del Busto, E. N.; Tecker, F.; Viganò, W.; Welsch, C. P.; Woolley, B. J.

    Due to the secondary showers generated when a particle hits the vacuum chamber, beam losses at an accelerator may be detected via radiation detectors located near the beam line. Several sources of background can limit the sensitivity and reduce the dynamic range of a Beam Loss Monitor (BLM). This document concentrates on potential sources of background generated near high gradient RF cavities due to dark current and voltage breakdowns. An optical fibre has been installed at an experiment of the Compact Linear Collider (CLIC) Test Facility (CTF3), where a dedicated study of the performance of a loaded and unloaded CLIC accelerating structure is undergoing. An analysis of the collected data and a benchmarking simulation are presented to estimate BLM sensitivity limitations. Moreover, the feasibility for the use of BLMs optimised for the diagnostics of RF cavities is discussed.

  10. H- Beam Stripping Loss at Background Partial Pressure of Ar

    Institute of Scientific and Technical Information of China (English)

    Hu Chundong; Wang Shaohu; Hu Liqun

    2005-01-01

    It has been observed that H- current could be improved by adding Ar to H2 plasma.But due to a slower pumping speed for Ar with the existing pumping scheme, the tank pressure will increase quickly during the length of a beam pulse. Since H- stripping loss depends on the tank pressure and gas species, part of the H- beam can be converted to H0 and then H0 can be converted into H+ with background H2 and Ar gas thickness. Therefore, the H- beam current,measured by a Faraday cup, situated at a distance L from GG (ground grid), will decrease because it will be converted into a H+ current. This gives a ratio of the Faraday cup net current to the H- beam current before stripping at background partial pressure of Ar.

  11. Beam loss reduction by magnetic shielding using beam pipes and bellows of soft magnetic materials

    Science.gov (United States)

    Kamiya, J.; Ogiwara, N.; Hotchi, H.; Hayashi, N.; Kinsho, M.

    2014-11-01

    One of the main sources of beam loss in high power accelerators is unwanted stray magnetic fields from magnets near the beam line, which can distort the beam orbit. The most effective way to shield such magnetic fields is to perfectly surround the beam region without any gaps with a soft magnetic high permeability material. This leads to the manufacture of vacuum chambers (beam pipes and bellows) with soft magnetic materials. A Ni-Fe alloy (permalloy) was selected for the material of the pipe parts and outer bellows parts, while a ferritic stainless steel was selected for the flanges. An austenitic stainless steel, which is non-magnetic material, was used for the inner bellows for vacuum tightness. To achieve good magnetic shielding and vacuum performances, a heat treatment under high vacuum was applied during the manufacturing process of the vacuum chambers. Using this heat treatment, the ratio of the integrated magnetic flux density along the beam orbit between the inside and outside of the beam pipe and bellows became small enough to suppress beam orbit distortion. The outgassing rate of the materials with this heat treatment was reduced by one order magnitude compared to that without heat treatment. By installing the beam pipes and bellows of soft magnetic materials as part of the Japan Proton Accelerator Research Complex 3 GeV rapid cycling synchrotron beam line, the closed orbit distortion (COD) was reduced by more than 80%. In addition, a 95.5% beam survival ratio was achieved by this COD improvement.

  12. Beam loss reduction by magnetic shielding using beam pipes and bellows of soft magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Kamiya, J., E-mail: kamiya.junichiro@jaea.go.jp; Ogiwara, N.; Hotchi, H.; Hayashi, N.; Kinsho, M.

    2014-11-01

    One of the main sources of beam loss in high power accelerators is unwanted stray magnetic fields from magnets near the beam line, which can distort the beam orbit. The most effective way to shield such magnetic fields is to perfectly surround the beam region without any gaps with a soft magnetic high permeability material. This leads to the manufacture of vacuum chambers (beam pipes and bellows) with soft magnetic materials. A Ni–Fe alloy (permalloy) was selected for the material of the pipe parts and outer bellows parts, while a ferritic stainless steel was selected for the flanges. An austenitic stainless steel, which is non-magnetic material, was used for the inner bellows for vacuum tightness. To achieve good magnetic shielding and vacuum performances, a heat treatment under high vacuum was applied during the manufacturing process of the vacuum chambers. Using this heat treatment, the ratio of the integrated magnetic flux density along the beam orbit between the inside and outside of the beam pipe and bellows became small enough to suppress beam orbit distortion. The outgassing rate of the materials with this heat treatment was reduced by one order magnitude compared to that without heat treatment. By installing the beam pipes and bellows of soft magnetic materials as part of the Japan Proton Accelerator Research Complex 3 GeV rapid cycling synchrotron beam line, the closed orbit distortion (COD) was reduced by more than 80%. In addition, a 95.5% beam survival ratio was achieved by this COD improvement.

  13. Synthesis of multiple shaped beam antenna patterns

    Science.gov (United States)

    Stutzman, W. L.; Coffey, E. L.

    1973-01-01

    Results are presented of research into the problem of finding an excitation of a given antenna such that the desired radiation pattern is approximated to within acceptable limits. This is to be done in such a fashion that boundary conditions involving hardware limitations may be inserted into the problem. The intended application is synthesis of multiple shaped beam antennas. Since this is perhaps the most difficult synthesis problem an antenna engineer is likely to encounter, the approach taken was to include as a by-product capability for synthesizing simpler patterns. The synthesis technique has been almost totally computerized. The class of antennas which may be synthesized with the computer program are those which may be represented as planar (continuous or discrete) current distributions. The technique is not limited in this sense and could indeed by extended to include, for example, the synthesis of conformal arrays or current distributions on the surface of reflectors. The antenna types which the program is set up to synthesize are: line source, rectangular aperture, circular aperture, linear array, rectangular array, and arbitrary planar array.

  14. Test of the LHC DIAMOND Beam Loss Monitors

    CERN Document Server

    Dehning, B; Effinger, E; Pernegger, H; Griesmayer, E

    2011-01-01

    Chemical Vapour Deposition(CVD) diamond detectors were installed in the collimation area of the CERN LHC to study their feasibility as Fast Beam Loss Monitors in a high-­radiation environment. Four detectors were configured with fast, radiation-­hard pre-amplifiers with a bandwidth of 2GHz. The readout was via an oscilloscope with a bandwidth of 1GHz and a sampling rate of 5 GSPS. Despite the 250m cable run from the detectors to the oscilloscope, particle losses were resolved with a 2ns rise time, a pulse width of 10ns and a time resolution of 615ps. Two modes of operation were applied. For the analysis of unexpected beam aborts, the loss profile was recorded in a 1ms buffer and, for nominal operation, the histogram of the time structure of the losses was recorded in synchronism with the LHC period of 89.2us. Measurements during the LHC start-­up (February to December 2010) are presented. The Diamond Monitors gave an unprecedented insight into the time structure of the beam losses resolving the LHC RF freq...

  15. LHC Beam Instrumentation: Beam Loss and Tune Measurements (3/3)

    CERN Document Server

    CERN. Geneva

    2014-01-01

    The LHC is equipped with a full suite of sophisticated beam instrumentation which has been essential for rapid commissioning, the safe increase in total stored beam power and the understanding of machine optics and accelerator physics phenomena. These lectures will introduce these systems and comment on their contributions to the various stages of beam operation. They will include details on: the beam position system and its use for real-time global orbit feedback; the beam loss system and its role in machine protection; total and bunch by bunch intensity measurements; tune measurement and feedback; diagnostics for transverse beam size measurements, abort gap monitoring and longitudinal density measurements. Issues and problems encountered along the way will also be discussed together with the prospect for future upgrades.

  16. Application of Diamond Based Beam Loss Monitors at LHC

    CERN Document Server

    AUTHOR|(CDS)2080642; Lohmann, W; Rüdiger, S

    2013-05-14

    The Large Hadron Collider (LHC) was conceived in the 1980s and started the operation in 2008. It needed more than 20 years to plan and construct this accelerator and its experiments. Four main experiments are located around the ring, Compact Muon Solenoid (CMS), A Toroidal LHC Apparatus (ATLAS), A Large Ion Collider Experiment (ALICE) and LHC beauty (LHCb). Two beams that traveling in opposite direction in the LHC tunnel, collide in each of the experiments. The navigation of the beams is done by over 10000 magnets and each beam has a stored energy of 362MJ which correspond to the kinetic energy of a train like the TGV travelling of 150km/h. Only a small percentage of that energy can damage the material in the LHC ring or the magnets. This would mean a repair time of months or years, without taking any data. To avoid such a scenario, it is important to monitor the beam condition and measure the amount of losses of the beam. Such losses can for example happen due to dust particles in the vacuum chambers or due...

  17. Ionization Chambers for the LHC Beam Loss Detection

    CERN Document Server

    Assmann, R W; Ferioli, G; Gschwendtner, E; Kain, V

    2003-01-01

    At the Large Hadron Collider (LHC) a beam loss system will be used to prevent and protect superconducting magnets against coil quenches and coil damages. Ionisation chambers will be mounted outside the cryostat to measure the secondary shower particles caused by lost beam particles. Since the stored particle beam intensity is eight orders of magnitude larger than the lowest quench level and the losses should be detected with a relative error of two, the design and the location of the detectors have to be optimised. For that purpose a two-fold simulation was carried out. The longitudinal loss locations of the tertiary halo is investigated by tracking the halo through several magnet elements. These loss distributions are combined with simulations of the particle fluence outside the cryostat, which is induced by lost protons at the vacuum pipe. The base-line ionisation chamber has been tested at the PS Booster in order to determine the detector response at the high end of the dynamic range.

  18. A Fast CVD Diamond Beam Loss Monitor for LHC

    CERN Document Server

    Griesmayer, E; Dobos, D; Effinger, E; Pernegger, H

    2011-01-01

    Chemical Vapour Deposition (CVD) diamond detectors were installed in the collimation area of the CERN LHC to study their feasibility as Fast Beam Loss Monitors in a high-radiation environment. The detectors were configured with a fast, radiation-hard pre-amplifier with a bandwidth of 2 GHz. The readout was via an oscilloscope with a bandwidth of 1 GHz and a sampling rate of 5 GSPS. Despite the 250 m cable run from the detectors to the oscilloscope, single MIPs were resolved with a 2 ns rise time, a pulse width of 10 ns and a time resolution of less than 1 ns. Two modes of operation were applied. For the analysis of unexpected beam aborts, the loss profile was recorded in a 1 ms buffer and, for nominal operation, the histogram of the time structure of the losses was recorded in synchronism with the LHC period of 89.2 μs. Measurements during the LHC start-up (February to December 2010) are presented. The Diamond Monitors gave an unprecedented insight into the time structure of the beam losses resolving the 400...

  19. RFQ Designs and Beam-Loss Distributions for IFMIF

    Energy Technology Data Exchange (ETDEWEB)

    Jameson, Robert A [ORNL

    2007-01-01

    The IFMIF 125 mA cw 40 MeV accelerators will set an intensity record. Minimization of particle loss along the accelerator is a top-level requirement and requires sophisticated design intimately relating the accelerated beam and the accelerator structure. Such design technique, based on the space-charge physics of linear accelerators (linacs), is used in this report in the development of conceptual designs for the Radio-Frequency-Quadrupole (RFQ) section of the IFMIF accelerators. Design comparisons are given for the IFMIF CDR Equipartitioned RFQ, a CDR Alternative RFQ, and new IFMIF Post-CDR Equipartitioned RFQ designs. Design strategies are illustrated for combining several desirable characteristics, prioritized as minimum beam loss at energies above ~ 1 MeV, low rf power, low peak field, short length, high percentage of accelerated particles. The CDR design has ~0.073% losses above 1 MeV, requires ~1.1 MW rf structure power, has KP factor 1.7,is 12.3 m long, and accelerates ~89.6% of the input beam. A new Post-CDR design has ~0.077% losses above 1 MeV, requires ~1.1 MW rf structure power, has KP factor 1.7 and ~8 m length, and accelerates ~97% of the input beam. A complete background for the designs is given, and comparisons are made. Beam-loss distributions are used as input for nuclear physics simulations of radioactivity effects in the IFMIF accelerator hall, to give information for shielding, radiation safety and maintenance design. Beam-loss distributions resulting from a ~1M particle input distribution representative of the IFMIF ECR ion source are presented. The simulations reported were performed with a consistent family of codes. Relevant comparison with other codes has not been possible as their source code is not available. Certain differences have been noted but are not consistent over a broad range of designs and parameter range. The exact transmission found by any of these codes should be treated as indicative, as each has various sensitivities in

  20. Performance and perspectives of the diamond based Beam Condition Monitor for beam loss monitoring at CMS

    CERN Document Server

    AUTHOR|(CDS)2080862

    2015-01-01

    At CMS, a beam loss monitoring system is operated to protect the silicon detectors from high particle rates, arising from intense beam loss events. As detectors, poly-crystalline CVD diamond sensors are placed around the beam pipe at several locations inside CMS. In case of extremely high detector currents, the LHC beams are automatically extracted from the LHC rings.Diamond is the detector material of choice due to its radiation hardness. Predictions of the detector lifetime were made based on FLUKA monte-carlo simulations and irradiation test results from the RD42 collaboration, which attested no significant radiation damage over several years.During the LHC operational Run1 (2010 â?? 2013), the detector efficiencies were monitored. A signal decrease of about 50 times stronger than expectations was observed in the in-situ radiation environment. Electric field deformations due to charge carriers, trapped in radiation induced lattice defects, are responsible for this signal decrease. This so-called polarizat...

  1. Benchmarking of collimation tracking using RHIC beam loss data.

    Energy Technology Data Exchange (ETDEWEB)

    Robert-Demolaize,G.; Drees, A.

    2008-06-23

    State-of-the-art tracking tools were recently developed at CERN to study the cleaning efficiency of the Large Hadron Collider (LHC) collimation system. In order to estimate the prediction accuracy of these tools, benchmarking studies can be performed using actual beam loss measurements from a machine that already uses a similar multistage collimation system. This paper reviews the main results from benchmarking studies performed with specific data collected from operations at the Relativistic Heavy Ion Collider (RHIC).

  2. Measurement of Beam Loss at the Australian Synchrotron

    CERN Document Server

    Holzer, EB; Kastriotou, M; Boland, MJ; Jackson, PD; Rasool, RP; Schmidt, J; Welsch, CP

    2014-01-01

    The unprecedented requirements that new machines are setting on their diagnostic systems is leading to the development of new generation of devices with large dynamic range, sensitivity and time resolution. Beam loss detection is particularly challenging due to the large extension of new facilities that need to be covered with localized detector. Candidates to mitigate this problem consist of systems in which the sensitive part of the radiation detectors can be extended over long distance of beam lines. In this document we study the feasibility of a BLM system based on optical fiber as an active detector for an electron storage ring. The Australian Synchrotron (AS) comprises a 216m ring that stores electrons up to 3GeV. The Accelerator has recently claimed the world record ultra low transverse emittance (below pm rad) and its surroundings are rich in synchrotron radiation. Therefore, the AS provides beam conditions very similar to those expected in the CLIC/ILC damping rings. A qualitative benchmark of beam l...

  3. The LCLS Undulator Beam Loss Monitor Readout System

    Energy Technology Data Exchange (ETDEWEB)

    Dusatko, John; Browne, M.; Fisher, A.S.; Kotturi, D.; Norum, S.; Olsen, J.; /SLAC

    2012-07-23

    The LCLS Undulator Beam Loss Monitor System is required to detect any loss radiation seen by the FEL undulators. The undulator segments consist of permanent magnets which are very sensitive to radiation damage. The operational goal is to keep demagnetization below 0.01% over the life of the LCLS. The BLM system is designed to help achieve this goal by detecting any loss radiation and indicating a fault condition if the radiation level exceeds a certain threshold. Upon reception of this fault signal, the LCLS Machine Protection System takes appropriate action by either halting or rate limiting the beam. The BLM detector consists of a PMT coupled to a Cherenkov radiator located near the upstream end of each undulator segment. There are 33 BLMs in the system, one per segment. The detectors are read out by a dedicated system that is integrated directly into the LCLS MPS. The BLM readout system provides monitoring of radiation levels, computation of integrated doses, detection of radiation excursions beyond set thresholds, fault reporting and control of BLM system functions. This paper describes the design, construction and operational performance of the BLM readout system.

  4. Single Gain Radiation Tolerant LHC Beam Loss Acquisition Card

    CERN Document Server

    Effinger, E; Emery, J; Ferioli, G; Zamantzas, C

    2008-01-01

    The beam loss monitoring system is one of the most critical elements for the protection of the LHC. It must prevent the super conducting magnets from quenches and the machine components from damages, caused by beam losses. Ionization chambers and secondary emission based detectors are used at several locations around the ring. The sensors are producing a signal current, which is related to the losses. This current will be measured by a tunnel card, which acquires, digitizes and transmits the data via an optical link to the surface electronic. The usage of the system, for protection and tuning of the LHC and the scale of the LHC, imposed exceptional specifications of the dynamic range and radiation tolerance. The input dynamic allows measurements between 10pA and 1mA and its protected to high pulse of 1.5kV and its corresponding current. To cover this range, a current to frequency converter in combination with an ADC is used. The integrator output voltage is measured with an ADC to improve the resolution. The ...

  5. Beam Loss Ion Chamber System Upgrade for Experimental Halls

    CERN Document Server

    Dotson, Danny W

    2005-01-01

    The Beam loss Ion Chamber System (BLICS) was developed to protect Jefferson Labs transport lines, targets and beam dumps from a catastrophic "burn through." Range changes and testing was accomplished manually requiring the experiment to be shut down. The new upgraded system is based around an "off the shelf" Programmable Logic Controller located in a single controll box supporting up to ten individual detectors. All functions that formerly required an entry into the experimental hall and manual adjustment can be accomplished from the Machine Control Center (MCC). A further innovation was the addition of a High Voltage "Brick" at the detector location. A single cable supplies the required voltage for the Brick and a return line for the ion chamber signal. The read back screens display range, trip point, and accumulated dose for each location. The new system is very cost effective and significantly reduces the amount of lost experimental time.

  6. 2014 CERN Accelerator Schools: Beam Loss and Accelerator Protection

    CERN Multimedia

    2014-01-01

    The US-CERN-JAPAN-RUSSIA Joint International Accelerator School is organising a course on Beam Loss and Accelerator Protection to be held in Newport Beach, California, USA from 5-14 November, 2014.    This school is intended for physicists and engineers who are or may be engaged in the design, construction, and/or operation of accelerators with high power photon or particle beams and/or accelerator sub-systems with large stored energy. Application deadlines are 15 August and 4 September. Further information on this Joint School can be found at: http://cas.web.cern.ch/cas/JAS/Newport%20Beach%202014/NPBadvert.html http://indico.cern.ch/event/287647/ http://uspas.fnal.gov/programs/JAS/JAS14.shtml

  7. Prompt loss of beam ions in KSTAR plasmas

    Science.gov (United States)

    Kim, Jun Young; Rhee, T.; Kim, Junghee; Yoon, S. W.; Park, B. H.; Isobe, M.; Ogawa, K.; Ko, W.-H.

    2016-10-01

    For a toroidal plasma facility to realize fusion energy, researching the transport of fast ions is important not only due to its close relation to the heating and current drive efficiencies but also to determine the heat load on the plasma-facing components. We present a theoretical analysis and orbit simulation for the origin of lost fast-ions during neutral beam injection (NBI) heating in Korea Superconducting Tokamak Advanced Research (KSTAR) device. We adopted a two-dimensional phase diagram of the toroidal momentum and magnetic moment and describe detectable momentums at the fast-ion loss detector (FILD) position as a quadratic line. This simple method was used to model birth ions deposited by NBI and drawn as points in the momentum phase space. A Lorentz orbit code was used to calculate the fast-ion orbits and present the prompt loss characteristics of the KSTAR NBI. The scrape-off layer deposition of fast ions produces a significant prompt loss, and the model and experimental results closely agreed on the pitch-angle range of the NBI prompt loss. Our approach can provide wall load information from the fast ion loss.

  8. Prompt loss of beam ions in KSTAR plasmas

    Directory of Open Access Journals (Sweden)

    Jun Young Kim

    2016-10-01

    Full Text Available For a toroidal plasma facility to realize fusion energy, researching the transport of fast ions is important not only due to its close relation to the heating and current drive efficiencies but also to determine the heat load on the plasma-facing components. We present a theoretical analysis and orbit simulation for the origin of lost fast-ions during neutral beam injection (NBI heating in Korea Superconducting Tokamak Advanced Research (KSTAR device. We adopted a two-dimensional phase diagram of the toroidal momentum and magnetic moment and describe detectable momentums at the fast-ion loss detector (FILD position as a quadratic line. This simple method was used to model birth ions deposited by NBI and drawn as points in the momentum phase space. A Lorentz orbit code was used to calculate the fast-ion orbits and present the prompt loss characteristics of the KSTAR NBI. The scrape-off layer deposition of fast ions produces a significant prompt loss, and the model and experimental results closely agreed on the pitch-angle range of the NBI prompt loss. Our approach can provide wall load information from the fast ion loss.

  9. Impedances and power losses for an off-axis beam

    CERN Document Server

    Kurennoy, S S

    1996-01-01

    A method for calculating coupling impedances and power losses for off-axis beams is developed. It is applied to calculate impedances of small localized discontinuities like holes and slots, as well as the impedance due to a finite resistivity of chamber walls, in homogeneous chambers with an arbitrary shape of the chamber cross section. The approach requires to solve a two-dimensional electrostatic problem, which can be easily done numerically in the general case, while for some particular cases analytical solutions are obtained.

  10. The LHC beam loss monitoring system commissioning for 2010

    CERN Document Server

    Zamantzas, C; Chery, C; Effinger, E; Emery, J; Grishin, S; Hajdu, C F; Holzer, E B; Jackson, S; Kurfuerst, C; Marsili, A; Nordt, A; Sapinski, M; Tissier, R; Venturini, G G

    2010-01-01

    The LHC Beam Loss Monitoring (BLM) system is one of the most complex instrumentation systems deployed in the LHC. In addition to protecting the collider, the system also needs to provide a means of diagnosing machine faults and deliver feedback of the losses to the control room as well as to several systems for their setup and analysis. It has to transmit and process signals from approximately 4’000 monitors, and has nearly 3 million configurable parameters. This paper will discuss its performance and ability to provide the expected measurements, the problems encountered and necessary improvements, the adequacy of related software and databases, and in general its readiness and suitability for 3.5 TeV operation.

  11. Apertures in the LHC Beam Dump System and Beam Losses During Beam Abort

    CERN Document Server

    Kramer, T; Gyr, M; Koschik, A; Uythoven, J; Weiler, T

    2008-01-01

    The LHC beam dumping system (LBDS) is used to dispose accelerated protons and ions in a wide energy range from 450 GeV up to 7 TeV. An abort gap of $3 \\mu$s is foreseen to avoid sweeping particles through the LHC ring aperture. This paper gives a brief overview of the critical apertures in the extraction region and the two beam dump lines. MAD-X tracking studies have been made to investigate the impact of particles swept through the aperture due to extraction kicker failures or the presence of particles within the abort gap. The issue of failures during beam abort is a major concern for machine protection as well as a critical factor for safe operation of the experiments and their detectors.

  12. Fabrication of patterned mirror modules for generating laser line beams

    Science.gov (United States)

    Lee, Changyun; Kim, Taeggyum; Hong, Sangsu; Kim, Baekyun

    2008-02-01

    A method for fabricating Ag coated beam splitter is reported. This is showing specific patterned transmittance by immersing glass substrates in the mixture of H IISO 4 and H IIO II to make negatively charged oxygen sites at silica surface and then in ethanolic solutions of AgNO 3 and butylamine. We controlled the soaking time and molar ratios of the mixture of AgNO 3 and butylamine to pattern % transmittance of electroless coated glass surface. Finally, we made a functionalized beam splitters showing step function like transmittance and applied this to make multiple laser beams for display and laser machining.

  13. Secondary Electron Emission Beam Loss Monitor for LHC

    CERN Document Server

    Dehning, B; Holzer, E B; Kramer, Daniel

    2008-01-01

    Beam Loss Monitoring (BLM) system is a vital part of the active protection of the LHC accelerators' elements. It should provide the number of particles lost from the primary hadron beam by measuring the radiation field induced by their interaction with matter surrounding the beam pipe. The LHC BLM system will use ionization chambers as standard detectors but in the areas where very high dose rates are expected, the Secondary Emission Monitor (SEM) chambers will be employed because of their high linearity, low sensitivity and fast response. The SEM needs a high vacuum for proper operation and has to be functional for up to 20 years, therefore all the components were designed according to the UHV requirements and a getter pump was included. The SEM electrodes are made of Ti because of its Secondary Emission Yield (SEY) stability. The sensitivity of the SEM was modeled in Geant4 via the Photo-Absorption Ionization module together with custom parameterization of the very low energy secondary electron production. ...

  14. Small angle scatter imaging from wide beam diffraction patterns

    Energy Technology Data Exchange (ETDEWEB)

    Wilkinson, Steven J [Department of Materials and Medical Sciences, Cranfield University, Shrivenham, Swindon, Wiltshire SN6 8LA (United Kingdom); Rogers, Keith D [Department of Materials and Medical Sciences, Cranfield University, Shrivenham, Swindon, Wiltshire SN6 8LA (United Kingdom); Hall, Chris J [School of Physics, Monash University, Victoria 3800 (Australia); Round, Adam R [EMBL c/o DESY, Building 25a, Notkestrasse 85, 22603 Hamburg (Germany)

    2007-05-07

    In this paper we report on the extension of the technique of mapping small angle x-ray scatter (SAXS) across a soft material specimen several millimetres square. In the conventional SAXS mapping technique a pencil beam of x-rays is raster scanned over the specimen with the scatter pattern recorded from each point in the raster. In our technique a wide, parallel beam is used, speeding up the data collection time considerably. An image processing algorithm is used to separate the scatter pattern features from individual points along the line of the beam. To test the efficacy of the technique a phantom was constructed using gelatin and rat tail tendon collagen. Collagen fibres in the phantom were arranged in quarters horizontally, diagonally and vertically leaving one quarter with just gelatin. The phantom was used to collect both raster scanned sets of SAXS patterns spaced at 0.25 mm horizontally and vertically and also a wide beam data set. The width of the beam in this case was approximately 7 mm. Using the third-order diffraction of rat tail tendon intensity data were gathered from each SAXS pattern and used to construct a map. Data from the raster scan image and that from the wide beam are compared. Finally using a phantom made from dehydrated rat tail tendon and paraffin wax a tomographic slice constructed using data from SAXS patterns is shown.

  15. Determination of Muzzle Velocity Loss by Bore Wear Pattern

    Institute of Scientific and Technical Information of China (English)

    LIU Yi-xin; WANG Gui-yu

    2007-01-01

    A method to determine muzzle velocity loss according to the actual measured bore wear pattern is proposed.Therefore, it is unnecessary to conduct live firing and other experiments for determination of muzzle velocity loss. It has been applied to a national military standard since July 1, 2004.

  16. A new beam loss detector for low-energy proton and heavy-ion accelerators

    Science.gov (United States)

    Liu, Zhengzheng; Crisp, Jenna; Russo, Tom; Webber, Robert; Zhang, Yan

    2014-12-01

    The Facility for Rare Isotope Beams (FRIB) to be constructed at Michigan State University shall deliver a continuous, 400 kW heavy ion beam to the isotope production target. This beam is capable of inflicting serious damage on accelerator components, e.g. superconducting RF accelerating cavities. A Beam Loss Monitoring (BLM) System is essential for detecting beam loss with sufficient sensitivity and promptness to inform the machine protection system (MPS) and operations personnel of impending dangerous losses. Radiation transport simulations reveal shortcomings in the use of ionization chambers for the detection of beam losses in low-energy, heavy-ion accelerators. Radiation cross-talk effects due to the folded geometry of the FRIB LINAC pose further complications to locating specific points of beam loss. We propose a newly developed device, named the Loss Monitor Ring (LMR1

  17. Loss of accuracy using smeared properties in composite beam modeling

    Science.gov (United States)

    Liu, Ning

    Advanced composite materials have broad, proven applications in many engineering systems ranging from sports equipment sectors to components on the space shuttle because of their lightweight characteristics and significantly high stiffness. Together with this merit of composite materials is the challenge of improving computational simulation process for composites analysis. Composite structures, particularly composite laminates, usually consist of many layers with different lay-up angles. The anisotropic and heterogeneous features render 3D finite element analysis (FEA) computationally expensive in terms of the computational time and the computing power. At the constituent level, composite materials are heterogeneous. But quite often one homogenizes each layer of composites, i.e. lamina, and uses the homogenized material properties as averaged (smeared) values of those constituent materials for analysis. This is an approach extensively used in design and analysis of composite laminates. Furthermore, many industries tempted to use smeared properties at the laminate level to further reduce the model of composite structures. At this scale, smeared properties are averaged material properties that are weighted by the layer thickness. Although this approach has the advantage of saving computational time and cost of modeling significantly, the prediction of the structural responses may not be accurate, particularly the pointwise stress distribution. Therefore, it is important to quantify the loss of accuracy when one uses smeared properties. In this paper, several different benchmark problems are carefully investigated in order to exemplify the effect of the smeared properties on the global behavior and pointwise stress distribution of the composite beam. In the classical beam theory, both Newtonian method and variational method include several ad hoc assumptions to construct the model, however, these assumptions are avoided if one uses variational asymptotic method. VABS

  18. Application of stencil masks for ion beam lithographic patterning

    Energy Technology Data Exchange (ETDEWEB)

    Brun, S., E-mail: sebastien.brun@he-arc.ch [Institut des Microtechnologies Appliquées, Haute Ecole Arc Ingénierie, Eplatures-Grise 17, CH-2300 La Chaux-de-Fonds (Switzerland); Savu, V. [Laboratoire des Microsystèmes (LMIS), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Schintke, S. [HEIG-VD, University of Applied Sciences of Western Switzerland, Institut de Micro et Nano Techniques – Laboratory of Applied NanoSciences (MNT-LANS), Route de Cheseaux 1, CH-1401 Yverdon-les-Bains (Switzerland); Guibert, E.; Keppner, H. [Institut des Microtechnologies Appliquées, Haute Ecole Arc Ingénierie, Eplatures-Grise 17, CH-2300 La Chaux-de-Fonds (Switzerland); Brugger, J. [Laboratoire des Microsystèmes (LMIS), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Whitlow, H.J. [Institut des Microtechnologies Appliquées, Haute Ecole Arc Ingénierie, Eplatures-Grise 17, CH-2300 La Chaux-de-Fonds (Switzerland)

    2013-07-01

    The application of Au/Si{sub 3}N{sub 4} stencil masks for the transfer of patterns using different MeV-ion beams with various substrates has been investigated. The techniques investigated were namely, conventional lithography with positive- and negative-tone resist polymers, oxygen ion-induced etching of PTFE and patterning using an etch-stop in silicon. We demonstrate that using different well-known microtechnology material-modification techniques, patterns can be transferred using stencil masks and broad ion beams to nanomachining scenarios. In the case of the etch-stop process; writing of 3D micropatterns with different height levels was achieved using a broad beam. The stencil masks were found to be durable with no obvious deterioration and well suited for exposure of large areas.

  19. The Fermilab Main Injector: high intensity operation and beam loss control

    CERN Document Server

    Brown, Bruce C; Capista, David; Chou, Weiren; Kourbanis, Ioanis; Morris, Denton K; Seiya, Kiyomi; Wu, Guan Hong; Yang, Ming-Jen

    2013-01-01

    From 2005 through 2012, the Fermilab Main Injector provided intense beams of 120 GeV protons to produce neutrino beams and antiprotons. Hardware improvements in conjunction with improved diagnostics allowed the system to reach sustained operation at ~400 kW beam power. Transmission was very high except for beam lost at or near the 8 GeV injection energy where 95% beam transmission results in about 1.5 kW of beam loss. By minimizing and localizing loss, residual radiation levels fell while beam power was doubled. Lost beam was directed to either the collimation system or to the beam abort. Critical apertures were increased while improved instrumentation allowed optimal use of available apertures. We will summarize the improvements required to achieve high intensity, the impact of various loss control tools and the status and trends in residual radiation in the Main Injector.

  20. Comparative study of beam losses and heat loads reduction methods in MITICA beam source

    Energy Technology Data Exchange (ETDEWEB)

    Sartori, E., E-mail: emanuele.sartori@igi.cnr.it; Agostinetti, P.; Dal Bello, S.; Marcuzzi, D.; Serianni, G.; Veltri, P. [Consorzio RFX, Euratom-ENEA association, C.so Stati Uniti 4, 35127 Padova (Italy); Sonato, P. [Consorzio RFX, Euratom-ENEA association, C.so Stati Uniti 4, 35127 Padova (Italy); Dipartimento di Ingegneria Elettrica, Padova University, Via Gradenigo 6/a, 35131 Padova (Italy)

    2014-02-15

    In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.

  1. Comparative study of beam losses and heat loads reduction methods in MITICA beam source

    Science.gov (United States)

    Sartori, E.; Agostinetti, P.; Dal Bello, S.; Marcuzzi, D.; Serianni, G.; Sonato, P.; Veltri, P.

    2014-02-01

    In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.

  2. Reliability Tests of the LHC Beam Loss Monitoring FPGA Firmware

    CERN Document Server

    Hajdu, C F; Dehning, B; Jackson, S

    2010-01-01

    The LHC Beam Loss Monitoring (BLM) system is one of the most complex instrumentation systems deployed in the LHC. In addition to protecting the collider, the system also needs to provide a means of diagnosing machine faults and deliver a feedback of losses to the control room as well as to several systems for their setup and analysis. It has to transmit and process signals from almost 4’000 monitors, and has nearly 3 million configurable parameters. In a system of such complexity, firmware reliability is a critical issue. The integrity of the signal chain of the LHC BLM system and its ability to correctly detect unwanted scenarios and thus provide the required protection level must be ensured. In order to analyze the reliability and functionality, an advanced verification environment has been developed to evaluate the performance and response of the FPGA-based data analysis firmware. This paper will report on the numerous tests that have been performed and on how the results are used to quantify the reliabi...

  3. NANOSTRUCTURE PATTERNING UNDER ENERGETIC PARTICLE BEAM IRRADIATION

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lumin [Regents of the University of Michigan; Lu, Wei [Regents of the University of Michigan

    2013-01-31

    Energetic ion bombardment can lead to the development of complex and diverse nanostructures on or beneath the material surface through induced self-organization processes. These self-organized structures have received particular interest recently as promising candidates as simple, inexpensive, and large area patterns, whose optical, electronic and magnetic properties are different from those in the bulk materials [1-5]. Compared to the low mass efficiency production rate of lithographic methods, these self-organized approaches display new routes for the fabrication of nanostructures over large areas in a short processing time at the nanoscale, beyond the limits of lithography [1,4]. Although it is believed that surface nanostructure formation is based on the morphological instability of the sputtered surface, driven by a kinetic balance between roughening and smoothing actions [6,7], the fundamental mechanisms and experimental conditions for the formation of these nanostructures has still not been well established, the formation of the 3-D naopatterns beneath the irradiated surface especially needs more exploration. During the last funding period, we have focused our efforts on irradiation-induced nanostructures in a broad range of materials. These structures have been studied primarily through in situ electron microscopy during electron or ion irradiation. In particular, we have performed studies on 3-D void/bubble lattices (in metals and CaF2), embedded sponge-like porous structure with uniform nanofibers in irradiated semiconductors (Ge, GaSb, and InSb), 2-D highly ordered pattern of nanodroplets (on the surface of GaAs), hexagonally ordered nanoholes (on the surface of Ge), and 1-D highly ordered ripple and periodic arrays (of Cu nanoparticles) [3,8-11]. The amazing common feature in those nanopatterns is the uniformity of the size of nanoelements (nanoripples, nanodots, nanovoids or nanofibers) and the distance separating them. Our research focuses on the

  4. Cryogenic Beam Loss Monitors for the Superconducting Magnets of the LHC

    CERN Document Server

    Bartosik, MR; Sapinski, M; Kurfuerst, C; Griesmayer, E; Eremin, V; Verbitskaya, E

    2014-01-01

    The Beam Loss Monitor detectors close to the interaction points of the Large Hadron Collider are currently located outside the cryostat, far from the superconducting coils of the magnets. In addition to their sensitivity to lost beam particles, they also detect particles coming from the experimental collisions, which do not contribute significantly to the heat deposition in the superconducting coils. In the future, with beams of higher energy and brightness resulting in higher luminosity, distinguishing between these interaction products and dangerous quench-provoking beam losses from the primary proton beams will be challenging. The system can be optimised by locating beam loss monitors as close as possible to the superconducting coils, inside the cold mass in a superfluid helium environment, at 1.9 K. The dose then measured by such Cryogenic Beam Loss Monitors would more precisely correspond to the real dose deposited in the coil. The candidates under investigation for such detectors are based on p+-n-n+ si...

  5. Mitigation of Numerical Noise for Beam Loss Simulations Proc. HB2016 Malmo, Sweden

    CERN Document Server

    Kesting, Frederik

    2017-01-01

    Numerical noise emerges in self-consistent simulations of charged particles, and its mitigation is investigated since the first numerical studies in plasma physics. In accelerator physics, recent studies find an artificial diffusion of the particle beam due to numerical noise in particle-in-cell tracking, which is of particular importance for high intensity machines with a long storage time, as the SIS100 at FAIR or in context of the LIU upgrade at CERN. In beam loss simulations for these projects artificial effects must be distinguished from physical beam loss. Therefore, it is important to relate artificial diffusion to artificial beam loss, and to choose simulation parameters such that physical beam loss is well resolved. As a practical tool, we therefore suggest a scaling law to find optimal simulation parameters for a given maximum percentage of acceptable artificial beam loss.

  6. Beam Pattern Synthesis Based on Hybrid Optimization Algorithm

    Institute of Scientific and Technical Information of China (English)

    YU Yan-li; WANG Ying-min; LI Lei

    2010-01-01

    As conventional methods for beam pattern synthesis can not always obtain the desired optimum pattern for the arbitrary underwater acoustic sensor arrays, a hybrid numerical synthesis method based on adaptive principle and genetic algorithm was presented in this paper. First, based on the adaptive theory, a given array was supposed as an adaptive array and its sidelobes were reduced by assigning a number of interference signals in the sidelobe region. An initial beam pattern was obtained after several iterations and adjustments of the interference intensity, and based on its parameters, a desired pattern was created. Then, an objective function based on the difference between the designed and desired patterns can be constructed. The pattern can be optimized by using the genetic algorithm to minimize the objective function. A design example for a double-circular array demonstrates the effectiveness of this method. Compared with the approaches existing before, the proposed method can reduce the sidelobe effectively and achieve less synthesis magnitude error in the mainlobe.The method can search for optimum attainable pattern for the specific elements if the desired pattern can not be found.

  7. Development, Production and Testing of 4500 Beam Loss Monitors

    CERN Document Server

    Holzer, E B; Dehning, B; Ferioli, G; Grishin, V; Jimenez, T M; Koshelev, A; Kramer, Daniel; Larionov, A; Taborelli, M; Seleznev, V; Sleptsov, M; Sytin, A; Wevers, I

    2008-01-01

    Beam-loss monitoring (BLM) [1] is a key element in the LHC machine protection. 4250 nitrogen filled ionization chambers (IC) and 350 secondary emission monitors (SEM) have been manufactured and tested at the Institute for High Energy Physics (IHEP) in Protvino, Russia, following their development at CERN. Signal speed and robustness against aging were the main design criteria. Each monitor is permanently sealed inside a stainless-steel cylinder. The quality of the welding was a critical aspect during production. The SEMs are requested to hold a vacuum of $10^{-7}$ bar. Impurity levels from thermal and radiationinduced desorption should remain in the range of parts per million in the ICs. To avoid radiation aging (up to $2·10^{8}$ Gy in 20 years) production of the chambers followed strict UHV requirements. IHEP designed and built the UHV production stand. Due to the required dynamic range of $10^{8}$, the leakage current of the monitors has to stay below 2 pA. Several tests during and after production were ...

  8. Treatment of female pattern hair loss with oral antiandrogens

    NARCIS (Netherlands)

    Sinclair, R; Wewerinke, M; Jolley, D

    2005-01-01

    Background It has not been conclusively established that female pattern hair loss (FPHL) is either due to androgens or responsive to oral antiandrogen therapy. Objectives To evaluate the efficacy of oral antiandrogen therapy in the management of women with FPHL using standardized photographic techni

  9. A fast beam loss monitor system for the KEK proton synchrotron complex

    Science.gov (United States)

    Holt, J. A.; Kishiro, J.; Arakawa, D.; Hiramatsu, S.

    1991-06-01

    Efforts to increase the intensity of the KEK proton synchrotron have led to the need for a new fast response beam loss monitor system. The design and some prelimitary test results of a new beam loss monitor system are presented.(AIP)

  10. The Long-Term Beam Losses in the CERN Injector Chain

    CERN Document Server

    AUTHOR|(CDS)2067411; Bartosik, Hannes; Benedetto, Elena; Damerau, Heiko; Forte, Vincenzo; Giovannozzi, Massimo; Goddard, Brennan; Hancock, Steven; Hanke, Klaus; Huschauer, Alexander; Kowalska, Magdalena; Mcateer, Meghan Jill; Metral, Elias; Mikulec, Bettina; Papaphilippou, Yannis; Rumolo, Giovanni; Sterbini, Guido; Wasef, Raymond; Arduini, Gianluigi; Meddahi, Malika; Chapochnikova, Elena

    2015-01-01

    For the production of the LHC type beams, but also for the high intensity ones, the budget allocated to losses in the CERN injector chain is maintained as tight as possi- ble, in particular to keep as low as possible the activation of the different machine elements. Various beam dynamics effects, like for example beam interaction with betatronic resonances, beam instabilities, but also reduced efficiency of the RF capture processes or RF noise, can produce losses even on a very long time scale. The main different mecha- nisms producing long term losses observed in the CERN injectors, and their cure or mitigation, will be revised.

  11. Evolutionary loss of animal regeneration: pattern and process.

    Science.gov (United States)

    Bely, Alexandra E

    2010-10-01

    The ability to regenerate lost or damaged body parts is widespread among animals and provides obvious potential benefits. It is therefore perplexing that this ability has become greatly restricted or completely lost in many lineages. Despite growing interest in the cellular and molecular basis of regeneration, our understanding of how and why regenerative abilities are lost remains rudimentary. In an effort to develop a framework for studying losses of regeneration, here I outline an approach for rigorously identifying such losses, review broad patterns of regenerative ability across animals, describe some of the clearest examples of regeneration loss, discuss some possible scenarios by which regeneration may be lost, and review recent work in annelids that is providing new insights into loss of regenerative ability.

  12. Particle Rate and Host Accelerator Beam Loss on the MICE Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Dobbs, Adam James [Imperial College, London (United Kingdom)

    2011-10-01

    A study is presented of particle rates in the MICE Muon Beamline and their relationship to beam loss produced in ISIS. A brief overview of neutrino physics is presented, together with a discussion on the Neutrino Factory as a motivation for MICE. An overview of MICE itself is then presented, highlighting the need for a systematic understanding of the relationship between the MICE target parameters, ISIS beam loss, and MICE particle rate. The variation of beam loss with target depth is examined and observed to be non-linear. The variation of beam loss with respect to the target dip time in the ISIS cycle is examined and observed to be approximately linear for dip times between 11.1 ms and 12.6 ms after ISIS injection, before tailing at earlier dip times. The variation of beam loss with particle rate is also observed to follow an approximately linear relationship from 0.05 V.ms to 4.7 V.ms beam loss, with a further strong indication that this continues up to 7.1 V.ms. Particle identification using time-of-flight data is used to give an insight into the relative abundances of each particle species present in the MICE beam. Estimates of muon rate are then produced as a function of beam loss. At a level of 2 V.ms beam loss ~10.9 muons per spill for a 3.2 ms spill with negative π → μ optics, and ~31.1 muons per 1 ms spill with positive π → μ optics are observed. Simulations using the ORBIT particle tracking code of the beam loss distributions around the ISIS ring, caused by the MICE target, are also presented and the implications for MICE running discussed.

  13. Pattern evolution during ion beam sputtering; reductionistic view

    Science.gov (United States)

    Kim, J.-H.; Kim, J.-S.

    2016-09-01

    The development of the ripple pattern during the ion beam sputtering (IBS) is expounded via the evolution of its constituent ripples. For that purpose, we perform numerical simulation of the ripple evolution that is based on Bradley-Harper model and its non-linear extension. The ripples are found to evolve via various well-defined processes such as ripening, averaging, bifurcation and their combinations, depending on their neighboring ripples. Those information on the growth kinetics of each ripple allow the detailed description of the pattern development in real space that the instability argument and the diffraction study both made in k-space cannot provide.

  14. Many-beam dynamical simulation of electron backscatter diffraction patterns

    Energy Technology Data Exchange (ETDEWEB)

    Winkelmann, Aimo [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Germany)], E-mail: winkelm@mpi-halle.mpg.de; Trager-Cowan, Carol; Sweeney, Francis [Department of Physics, University of Strathclyde, Glasgow G4 ONG, Scotland (United Kingdom); Day, Austin P. [Aunt Daisy Scientific Ltd., Dixton Rd., Monmouth, Gwent, NP25 3PP (United Kingdom); Parbrook, Peter [EPSRC National Centre for III-V Technologies, University of Sheffield (United Kingdom)

    2007-04-15

    We present an approach for the simulation of complete electron backscatter diffraction (EBSD) patterns where the relative intensity distributions in the patterns are accurately reproduced. The Bloch wave theory is applied to describe the electron diffraction process. For the simulation of experimental patterns with a large field of view, a large number of reflecting planes has to be taken into account. This is made possible by the Bethe perturbation of weak reflections. Very good agreement is obtained for simulated and experimental patterns of gallium nitride GaN{l_brace}0001{r_brace} at 20 kV electron energy. Experimental features like zone-axis fine structure and higher-order Laue zone rings are accurately reproduced. We discuss the influence of the diffraction of the incident beam in our experiment.

  15. Propagation of Gaussian beams in the presence of gain and loss

    CERN Document Server

    Graefe, Eva-Maria; Schubert, Roman

    2016-01-01

    We consider the propagation of Gaussian beams in a waveguide with gain and loss in the paraxial approximation governed by the Schr\\"odinger equation. We derive equations of motion for the beam in the semiclassical limit that are valid when the waveguide profile is locally well approximated by quadratic functions. For Hermitian systems, without any loss or gain, these dynamics are given by Hamilton's equations for the center of the beam and its conjugate momentum. Adding gain and/or loss to the waveguide introduces a non-Hermitian component, causing the width of the Gaussian beam to play an important role in its propagation. Here we show how the width affects the motion of the beam and how this may be used to filter Gaussian beams located at the same initial position based on their width.

  16. Beam pattern of sparse array for passive sonar

    Institute of Scientific and Technical Information of China (English)

    WU Guoqing; WANG Meigang

    2007-01-01

    This work aims at sparse array without grating lobe for passive sonar, in order to increase frequency band of the passive sonar and reduce the cost. According to traditional method, the distance between two contiguous sensors in sonar array should be less than the wavelength of highest frequency of the signal; otherwise the grating lobe appears on beam pattern. The paper realizes that the conclusion of the grating lobe emergence it is not fit to the passive sonar due to the sine wave signal model in traditional method, in fact the input of passive sonar is random signal. From three aspect of the computer simulation, real passive sonar signal and theory analysis, it is revealed that the grating lobe does not appear on beam pattern when the distance between two contiguous sensors in passive sonar array is longer than wavelength of highest frequency. Whitening of the radiated noise can widen the frequency band,to ensure the beam pattern without the grating lobe. The conclusion of the paper is: if the band of radiated noise is wide enough (broader than 1 octave), that the wavelength of signal can be shorter than the distance between two contiguous sensors in passive sonar without grating lobe.

  17. A prototype readout system for the Diamond Beam Loss Monitors at LHC

    CERN Document Server

    Effinger, E; Baer, T; Schmidt, R; Frais-Kölbl, H; Griesmayer, E

    2013-01-01

    Diamond Beam Loss Monitors are used at the LHC for the measurement of fast beam losses. In this note, specimen LHC loss measurements with the prototype readout system “ROSY” from CIVIDEC are presented. The readout system is FPGA-based for on-line, real-time, and dead-time-free data processing, including a Linuxbased server for the interconnection to a GUI. The loss analysis makes full use of the fast signal response of the diamond detectors with 1 ns time resolution and 6.7 ns double pulse resolution. Two examples are presented: applications of the Time Loss Histogram with 1.6 ns binning and 1.2 ns time jitter for loss measurements that are synchronized with the LHC revolution period and a beam-loss-based tune measurement for all circulating bunches in parallel.

  18. A Prototype Readout System for the Diamond Beam Loss Monitors at LHC

    CERN Document Server

    Effinger, E; Baer, T; Schmidt, R; Frais-Kölbl, H; Griesmayer, E; Kavrigin, P; CERN. Geneva. ATS Department

    2013-01-01

    Diamond Beam Loss Monitors are used at the LHC for the measurement of fast beam losses. In this note, specimen LHC loss measurements with the prototype readout system “ROSY” from CIVIDEC are presented. The readout system is FPGA-based for on-line, real-time, and dead-time-free data processing, including a Linux-based server for the interconnection to a GUI. The loss analysis makes full use of the fast signal response of the diamond detectors with 1 ns time resolution and 6.7 ns double pulse resolution. Two examples are presented: applications of the Time Loss Histogram with 1.6 ns binning and 1.2 ns time jitter for loss measurements that are synchronized with the LHC revolution period and a beam-loss-based tune measurement for all circulating bunches in parallel.

  19. Effect of Power Losses on Self-Focusing of High Intensity Laser Beam in Gases

    CERN Document Server

    Semak, V V

    2013-01-01

    A theoretical study of power loss from periphery of an ultrashort pulse laser beam and temporally resolved defocussing produced by laser induced plasma are performed using paraxial approximation. Our analysis incorporate consideration of spatial distribution of the laser beam irradiance and the results show that substantial power losses (10%-80%) occur from the beam periphery limiting length of a filament. It was also shown that generally accepted concept of self-focusing critical power is inconsistent with consideration of self-induced refraction of spatially distributed laser beam. A new criterion for self-focusing and hypothesis for multiple filamentation are proposed.

  20. Beam losses due to the foil scattering for CSNS/RCS

    CERN Document Server

    Huang, Ming-Yang; Wang, Sheng; Xu, Shou-Yan

    2012-01-01

    For the Rapid Cycling Synchrotron of China Spallation Neutron Source (CSNS/RCS), the stripping foil scattering generates the beam halo and gives rise to additional beam losses during the injection process. The interaction between the proton beam and the stripping foil was discussed and the foil scattering was studied. A simple model and the realistic situation of the foil scattering were considered. By using the codes ORBIT and FLUKA, the multi-turn phase space painting injection process with the stripping foil scattering for CSNS/RCS was simulated and the beam losses due to the foil scattering were obtained.

  1. TCDQ-TCT retraction and losses during asynchronous beam dump

    CERN Document Server

    Bracco, Chiara; Quaranta, Elena; CERN. Geneva. ATS Department

    2016-01-01

    The protection provided by the TCDQs in case of asynchronous beam dump depends strongly on their correct setup. They have to respect the strict hierarchy of the full collimation system and shield the tertiary collimators in the experimental regions. This MD aimed at performing asynchronous beam dump tests with different configurations, in order to assess the minimum allowed retraction between TCTs and TCDQs and, as a consequence, on the The protection provided by the TCDQs in case of asynchronous beam dump depends strongly on their correct setup. They have to respect the strict hierarchy of the full collimation system and shield the tertiary collimators in the experimental regions. This MD aimed at performing asynchronous beam dump tests with different configurations, in order to assess the minimum allowed retraction between TCTs and TCDQs and, as a consequence, on the β* reach.

  2. Electron Beam Pattern Writer For X-Ray Masks

    Science.gov (United States)

    Viswanathan, R.; Wilson, A. D.; Lafuente, J.; Voelker, H.; Kern, A.

    1984-03-01

    This paper discusses the capabilities of a vector scan electron-beam system as an X-ray mask writer for pattern geometries at and below one-half micron. The noise level in the deflection system has been reduced to an RMS value of 150 A over a 0.5 mm deflection field, thus making our exposure system usable in the one-quarter micron regime. Pattern geometries below 2000 A have been fabricated on a thin membrane. Drift compensation techniques, implemented in software, have reduced placement errors over the entire mask to less than 700 A. Accomplishments in the areas of noise reduction, bandwidth error compensation, system resolution, and improvements in pattern placement accuracy are discussed.

  3. Master masks for big patterns by electron-beam lithography

    Science.gov (United States)

    Zlobin, Vladimir A.; Mamonov, V. I.; Vasiljeva, Olga G.

    1995-05-01

    Modern technologies for power semiconductor devices, laser and micro optics, micromechanics requires microlithography of patterns having a large are up to 100 cm2 with complicate precise drawing. The electron beam lithography (EBL) tools with variable shape beam have good prospects for this purpose, but their application has a few problems in case of the tasks pointed above. The main problems are a great volume of information and a large exposure time of such patterns. We propose the system for preparation of the exposure data having more than 100 MB volume that consists from set of personal computers, network adapters, and software. The preparation of graphic information and exposure strategy are presented. The optimum exposure conditions are determined by program modeling the exposure process in dependence on the statistic distribution of sizes of EBL figures. Our method permits to decrease the exposure time in several times under certain conditions and brings that nearer to theoretical limit Tmin equals SD/IBmax, where Tmin is minimum exposure time, S is exposure area, D is dose density, IBmax is maximum beam current. This approach is valid if the basic factor limiting the writing speed is IBmax. The developed computer system and writing strategy was applied us for mask making on modified ZBA-21 tool. These masks were meant for production of power semiconductor and laser optics devices.

  4. PRELIMINARY DESIGN OF THE BEAM LOSS MONITORING SYSTEM FOR THE SNS.

    Energy Technology Data Exchange (ETDEWEB)

    WITKOVER,R.; GASSNER,D.

    2002-05-06

    The SNS to be built at Oak Ridge National Laboratory will provide a high average intensity 1 GeV beam to produce spallation neutrons. Loss of a even small percentage of this intense beam would result in high radiation. The Beam Loss Monitor (ELM) system must detect such small, long term losses yet be capable of measuring infrequent short high losses. The large dynamic range presents special problems for the system design. Ion chambers will be used as the detectors. A detector originally designed for the FNAL Tevatron, was considered but concerns about ion collection times and low collection efficiency at high loss rates favor a new design. The requirements and design concepts of the proposed approach will be presented. Discussion of the design and testing of the ion chambers and the analog j-Point end electronics will be presented. The overall system design will be described.

  5. Reliability of Beam Loss Monitors System for the Large Hadron Collider

    CERN Document Server

    Guaglio, Gianluca; Santoni, C

    2004-01-01

    The employment of superconducting magnets, in the high energies colliders, opens challenging failure scenarios and brings new criticalities for the whole system protection. For the LHC beam loss protection system, the failure rate and the availability requirements have been evaluated using the Safety Integrity Level (SIL) approach. A downtime cost evaluation is used as input for the SIL approach. The most critical systems, which contribute to the final SIL value, are the dump system, the interlock system, the beam loss monitors system and the energy monitor system. The Beam Loss Monitors System (BLMS) is critical for short and intense particles losses, while at medium and higher loss time it is assisted by other systems, such as the quench protection system and the cryogenic system. For BLMS, hardware and software have been evaluated in detail. The reliability input figures have been collected using historical data from the SPS, using temperature and radiation damage experimental data as well as using standar...

  6. Beam losses due to abrupt crab cavity failures in the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Baer, T.; Barranco, J.; Calaga, R.; Tomas, R.; Wenninger, B.; Yee, B.; Zimmermann, F.

    2011-03-28

    A major concern for the implementation of crab crossing in a future High-Luminosity LHC (HL-LHC) is machine protection in an event of a fast crab-cavity failure. Certain types of abrupt crab-cavity amplitude and phase changes are simulated to characterize the effect of failures on the beam and the resulting particle-loss signatures. The time-dependent beam loss distributions around the ring and particle trajectories obtained from the simulations allow for a first assessment of the resulting beam impact on LHC collimators and on sensitive components around the ring. Results for the nominal LHC lattice is presented.

  7. Basis for low beam loss in the high-current APT linac

    Energy Technology Data Exchange (ETDEWEB)

    Wangler, T.P.; Gray, E.R.; Krawczyk, F.L.; Kurennoy, S.S.; Lawrence, G.P.; Ryne, R.D. [Los Alamos National Lab., NM (United States); Crandall, K.R. [TECHSOURCE, Santa Fe, NM (United States)

    1998-12-31

    The present evidence that the APT proton linac design will meet its goal of low beam loss operation. The conclusion has three main bases: (1) extrapolation from the understanding of the performance of the 800-MeV LANSCE proton linac at Los Alamos, (2) the theoretical understanding of the dominant halo-forming mechanism in the APT accelerator from physics models and multiparticle simulations, and (3) the conservative approach and key principles underlying the design of the APT linac, which are aimed at minimizing beam halo and providing large apertures to reduce beam loss to a very low value.

  8. Reliability of Beam Loss Monitor Systems for the Large Hadron Collider

    CERN Document Server

    Guaglio, Gianluca; Santoni, C

    2005-01-01

    The increase of beam energy and beam intensity, together with the use of super conducting magnets, opens new failure scenarios and brings new criticalities for the whole accelerator protection system. For the LHC beam loss protection system, the failure rate and the availability requirements have been evaluated using the Safety Integrity Level (SIL) approach. A downtime cost evaluation is used as input for the SIL approach. The most critical systems, which contribute to the final SIL value, are the dump system, the interlock system, the beam loss monitors system, and the energy monitor system. The Beam Loss Monitors System (BLMS) is critical for short and intense particles losses at 7 TeV and assisted by the Fast Beam Current Decay Monitors at 450 GeV. At medium and higher loss time it is assisted by other systems, such as the quench protection system and the cryogenic system. For BLMS, hardware and software have been evaluated in detail. The reliability input figures have been collected using historical data...

  9. The upgraded data acquisition system for beam loss monitoring at the Fermilab Tevatron and Main Injector

    CERN Document Server

    Baumbaugh, A; Brown, B C; Capista, D; Drennan, C; Fellenz, B; Knickerbocker, K; Lewis, J D; Marchionni, A; Needles, C; Olson, M; Pordes, S; Shi, Z; Still, D; Thurman-Keup, R; Utes, M; Wu, J

    2011-01-01

    A VME-based data acquisition system for beam-loss monitors has been developed and is in use in the Tevatron and Main Injector accelerators at the Fermilab complex. The need for enhanced beam-loss protection when the Tevatron is operating in collider-mode was the main driving force for the new design. Prior to the implementation of the present system, the beam-loss monitor system was disabled during collider operation and protection of the Tevatron magnets relied on the quench protection system. The new Beam-Loss Monitor system allows appropriate abort logic and thresholds to be set over the full set of collider operating conditions. The system also records a history of beam-loss data prior to a beam-abort event for post-abort analysis. Installation of the Main Injector system occurred in the fall of 2006 and the Tevatron system in the summer of 2007. Both systems were fully operation by the summer of 2008. In this paper we report on the overall system design, provide a description of its normal operation, and...

  10. Stochastic Orbit Loss of Neutral Beam Ions From NSTX Due to Toroidal Alfven Eigenmode Avalanches

    Energy Technology Data Exchange (ETDEWEB)

    Darrow, D S; Fredrickson, E D; Gorelenkov, N N; Gorelenkova, M; Kubota, S; Medley, S S; Podesta, M; Shi, L

    2012-07-11

    Short toroidal Alfven eigenmode (TAE) avalanche bursts in the National Spherical Torus Experiment (NSTX) cause a drop in the neutron rate and sometimes a loss of neutral beam ions at or near the full injection energy over an extended range of pitch angles. The simultaneous loss of wide ranges of pitch angle suggests stochastic transport of the beam ions occurs. When beam ion orbits are followed with a guiding center code that incorporates plasma's magnetic equilibrium plus the measured modes, the predicted ranges of lost pitch angle are similar to those seen in the experiment, with distinct populations of trapped and passing orbits lost. These correspond to domains where the stochasticity extends in the orbit phase space from the region of beam ion deposition to the loss boundary.

  11. LHC magnet quench test with beam loss generated by wire scan

    CERN Document Server

    Sapinski, M; Dahlerup-Petersen, K; Dehning, B; Emery, j; Ferrari, A; Guerrero, A; Holzer, E B; Koujili, M; Lechner, A; Nebot, E; Scheubel, M; Steckert, J; Verweij, A; Wenninger, J

    2011-01-01

    Beam losses with millisecond duration have been observed in the LHC in 2010 and 2011. They are thought to be provoked by dust particles falling into the beam. These losses could compromise the LHC availability if they provoke quenches of superconducting magnets. In order to investigate the quench limits for this loss mechanism, a quench test using a wire scanner has been performed, with the wire movement through the beam mimicking a loss with similar spatial and temporal distribution as in the case of dust particles. This paper will show the conclusions reached for millisecond-duration dust-provoked quench limits. It will include details on the maximum energy deposited in the coil as estimated using FLUKA code, showing a reasonable agreement with quench limit estimated from the heat transfer code QP3. In addition, information on the damage limit for carbon wires in proton beamswill be presented, following electronmicroscope analysis which revealed strong wire sublimation.

  12. Incoherent vertical ion losses during multiturn stacking cooling beam injection

    Science.gov (United States)

    Syresin, E. M.

    2014-07-01

    The efficiency of the multiturn ion injection with electron cooling depends on two parameters, namely, cooling efficiency and ion lifetime. The lifetime of freshly injected ions is usually shorter than the lifetime of strongly cooled stacked ions. Freshly injected ions are lost in the vertical direction because the vertical acceptance of the synchrotron is usually a few times smaller than the horizontal acceptance. Incoherent vertical losses of freshly injected ions arise from their multiple scattering by residual gas atoms and transverse diffusion caused by stack noise. Reduced ion lifetime limits the multiturn injection efficiency. Analytical estimations and BETACOOL-based numerical evaluations of the vertical ion losses during multiturn injection are presented in comparison with the experimental data obtained at the HIMAC synchrotron and the S-LSR storage ring.

  13. Demonstration of low-loss electron beam transport and mm-wave experiments of the fusion-FEM

    NARCIS (Netherlands)

    Urbanus, W. H.; Bongers, W. A.; van Dijk, G.; van der Geer, C. A. J.; de Kruif, R.; Manintveld, P.; Pluygers, J.; Poelman, A. J.; Schüller, F. C.; Smeets, P. H. M.; Sterk, A. B.; Verhoeven, A. G. A.; Valentini, M.; van der Wiel, M. J.

    1998-01-01

    In the Fusion-FEM electrostatic Free Electron Maser, an electron beam loss current of less than 0.2% is essential for long-pulse operation. At reduced beam current, 3 A instead of the nominal 12 A, we have demonstrated electron beam acceleration and transport through the undulator at current losses

  14. FNAL Proton Source High Intensity Operations and Beam Loss Control

    CERN Document Server

    Garcia, F G

    2014-01-01

    The 40-year-old Fermilab Proton Source machines, constituted by the Pre-Injector, Linac and the synchrotron Booster, have been the workhorse of the Fermi National Accelerator Laboratory (Fermilab). During this time, the High Energy Physics Program has demanded an increase in proton throughput, especially during the past decade with the beginning of the neutrino program at Fermilab. In order to achieve a successful program, major upgrades and changes were made in Booster. Once again, the Proton Source has been charged to double their beam throughput, while maintain the present residual activation levels, to meet the laboratory Intensity Frontier program goals until new machines are built and operational to replace the Proton Source machines. This paper discusses the present performance of Booster and the plans involved in reaching even higher intensities.

  15. Patterns of non-embolic transient monocular visual field loss.

    Science.gov (United States)

    Petzold, Axel; Islam, Niaz; Plant, G T

    2013-07-01

    The aim of this study was to systematically describe the semiology of non-embolic transient monocular visual field loss (neTMVL). We conducted a retrospective case note analysis of patients from Moorfields Eye Hospital (1995-2007). The variables analysed were age, age of onset, gender, past medical history or family history of migraine, eye affected, onset, duration and offset, perception (pattern, positive and negative symptoms), associated headache and autonomic symptoms, attack frequency, and treatment response to nifedipine. We identified 77 patients (28 male and 49 female). Mean age of onset was 37 years (range 14-77 years). The neTMVL was limited to the right eye in 36 % to the left in 47 % and occurred independently in either eye in 5 % of cases. A past medical history of migraine was present in 12 % and a family history in 8 %. Headache followed neTMVL in 14 % and was associated with autonomic features in 3 %. The neTMB was perceived as grey in 35 %, white in 21 %, black in 16 % and as phosphenes in 9 %. Most frequently neTMVL was patchy 20 %. Recovery of vision frequently resembled attack onset in reverse. In 3 patients without associated headache the loss of vision was permanent. Treatment with nifedipine was initiated in 13 patients with an attack frequency of more than one per week and reduced the attack frequency in all. In conclusion, this large series of patients with neTMVL permits classification into five types of reversible visual field loss (grey, white, black, phosphenes, patchy). Treatment response to nifidipine suggests some attacks to be caused by vasospasm.

  16. Shielding NSLS-II light source: Importance of geometry for calculating radiation levels from beam losses

    Science.gov (United States)

    Kramer, S. L.; Ghosh, V. J.; Breitfeller, M.; Wahl, W.

    2016-11-01

    Third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produces significantly higher neutron component dose to the experimental floor than a lower energy beam injection and ramped operations. Minimizing this dose will require adequate knowledge of where the miss-steered beam can occur and sufficient EM shielding close to the loss point, in order to attenuate the energy of the particles in the EM shower below the neutron production threshold (energy on the bulk shield walls and thereby the dose penetrating the shield walls. Designing supplemental shielding near the loss point using the analytic shielding model is shown to be inadequate because of its lack of geometry specification for the EM shower process. To predict the dose rates outside the tunnel requires detailed description of the geometry and materials that the beam losses will encounter inside the tunnel. Modern radiation shielding Monte-Carlo codes, like FLUKA, can handle this geometric description of the radiation transport process in sufficient detail, allowing accurate predictions of the dose rates expected and the ability to show weaknesses in the design before a high radiation incident occurs. The effort required to adequately define the accelerator geometry for these codes has been greatly reduced with the implementation of the graphical interface of FLAIR to FLUKA. This made the effective shielding process for NSLS-II quite accurate and reliable. The principles used to provide supplemental shielding to the NSLS-II accelerators and

  17. Study of Acquisition Electronics with a High Dynamic Range for a Beam Loss Measurement System

    CERN Document Server

    Venturini, G; Dehning, B; Effinger, E

    2010-01-01

    The particles accelerated in CERN accelerator chain reach high energies, topped by the particle energy at collision in the LHC, 7 GeV. During the operation, an amount of particles is inevitably lost from the beam. Depending on the extent of the losses, physical damage to machine components may be caused and the shower of secondary emission particles deposits energy in the surrounding equipment constituting the accelerator. The hadronic cascade also activates their materials, representing a hazard to the workers at CERN. In the LHC, the superconducting magnets that constitute the synchrotron lattice are kept at an operating temperature of 1:9K through a cryogenic facility employing superliquid helium, the increase in their temperature potentially initiates a quench. In the SPS, the damage due to a lost beam is also visible. The Beam Loss Monitoring (BLM) system has been developed to reliably protect the machines composing CERN’s accelerator chain and additionally provide information about the beam status: th...

  18. Study on beam loss system of BEPCII%BEPCII束损系统研究

    Institute of Scientific and Technical Information of China (English)

    何俊; 赵晓岩; 汪林; 杜垚垚; 赵颖; 随艳峰; 岳军会; 曹建社

    2015-01-01

    为更好掌握储存环中的束流状态,在北京正负电子对撞机二期工程的储存环上建立了以二极管为探测器的束流损失探测系统。用蒙特卡罗软件对损失束流产生簇射电子的分布情况进行了模拟,为安装束损探测器位置提供了依据。搭建了包括探头、数据获取系统、数据传输系统在内的束损系统。对束损过程进行了详细的分析与描述。对北京正负电子对撞机多年的束损数据进行了整理分析,对其在丢束诊断、束流寿命研究等多个方面应用情况进行了总结。数据显示建立的束损系统工作状态稳定,是优化机器参数、改善束流寿命、分析丢束过程的有力工具。%Background: A beam loss system that uses the PIN diode as the detector has been set up on Beijing Electron–Positron Collider II (BEPCII) storage after 8-a routine operation. Further study and analysis should been carried out based on the historical data.Purpose: This study aims to learn the beam loss process in depth and further optimize the parameters of the accelerator.Methods: Based on the machine size and beam parameter of BEPCII, the Monte Carlo simulation of the cluster electrons in the storage ring was performed to provide reference for installation position of the beam loss system. Then different methods, including adding all the beam loss monitor (BLM) counts, adding the inner detector, adding the outer detector, have been used for data analysis of the beam life time, beam loss distribution, beam envelope and dispersion,etc., under both the collider mode and synchrotron mode.Results: The results show that the BLM system is useful to study the beam life time and diagnose the beam loss processes. The beam loss system for BEPCII works stablely. The detector counts are much smaller than the dynamic range of the detector.Conclusion: Over the eight years, the response of the beam loss system does not change a lot, which implies that the

  19. An investigation of acoustic beam patterns for the sonar localization problem using a beam based method.

    Science.gov (United States)

    Guarato, Francesco; Windmill, James; Gachagan, Anthony; Harvey, Gerald

    2013-06-01

    Target localization can be accomplished through an ultrasonic sonar system equipped with an emitter and two receivers. Time of flight of the sonar echoes allows the calculation of the distance of the target. The orientation can be estimated from knowledge of the beam pattern of the receivers and the ratio, in the frequency domain, between the emitted and the received signals after compensation for distance effects and air absorption. The localization method is described and, as its performance strongly depends on the beam pattern, the search of the most appropriate sonar receiver in order to ensure the highest accuracy of target orientation estimations is developed in this paper. The structure designs considered are inspired by the ear shapes of some bat species. Parameters like flare rate, truncation angle, and tragus are considered in the design of the receiver structures. Simulations of the localization method allow us to state which combination of those parameters could provide the best real world implementation. Simulation results show the estimates of target orientations are, in the worst case, 2° with SNR = 50 dB using the receiver structure chosen for a potential practical implementation of a sonar system.

  20. Simulation of ion beam losses in LHC magnets

    CERN Document Server

    AUTHOR|(CDS)2068843; Jowett, John M; Riklund, R

    2005-01-01

    At the particle physics laboratory CERN, the largest accelerator ever, the Large Hadron Collider (LHC), is under construction. In the LHC ultra relativistic particles, mainly protons but also lead ions, will be brought into collision. One problem that arises in the operation is that colliding ion beams in the machine have a very large cross section for electromagnetic interactions, in particular Bound Free Pair Production (BFPP). An electron-positron pair is created by the electromagnetic field between two colliding particles and the electron is created in a bound state of one of the ions. Because of this reaction the ion changes its charge and therefore leaves the wanted trajectory and crashes in a superconducting magnet, depositing heat. The impact of the wrongly charged ions on the inside of the vacuum pipe was simulated with the simulation program FLUKA. It was concluded that it is not likely that enough heat is deposited in the coils of the superconducting magnet to induce a quench, although some uncerta...

  1. Beam-loss-induced electrical stress test on CMS Silicon Strip Modules

    CERN Document Server

    Fahrer, M; Hartmann, F; Heier, S; MacPherson, A; Muller, T H; Weiler, T h

    2004-01-01

    Based on simulated LHC beam loss scenarios, fully depleted CMS silicon tracker modules and sensors were exposed to 42 ns-long beam spills of approximately 10**1**1 protons per spill at the PS at CERN. The ionisation dose was sufficient to short circuit the silicon sensors. The dynamic behaviour of bias voltage, leakage currents and voltages over coupling capacitors were monitored during the impact. Results of pre- and post-qualification as well as the dynamic behaviour are shown.

  2. The Effect of Bone Loss Pattern on the Structural Capacity of the Proximal Femur

    Institute of Scientific and Technical Information of China (English)

    FAN Li-xia; Eric Wang

    2006-01-01

    The effect of age-related bone loss on the structural capacity of the proximal femur were investigated by Finite Element Analysis(FEA). Four bone loss patterns were considered. These were "uniform cortical bone loss", "neck cortical bone loss", "intertrochanteric cortical bone loss" and "uniform trabecular bone loss". The results show that the two "non-uniform cortical bone loss" patterns are more dangerous than the "uniform cortical bone loss" pattern, and that the cortical bone loss in intertrochanteric region is associated with a greater reduction in cortical failure load than the cortical bone loss in the femoral neck. The trabecular bone loss causes a limited decrease in both cortical failure and trabecular failure loads. This research should be helpful to the clinical assessment of femur fracture risk due to age-related bone loss.

  3. Evaluation of source term induced by beam loss in the superconducting linear accelerator at RAON

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Jin; Kim, Su Na; Nam, Shin Woo; Chung, Yon Sei [Rare Isotope Science Project, Institute for Basic Science, Daejeon (Korea, Republic of)

    2014-11-15

    As a new world-class heavy ion accelerator, RAON is able to accelerate heavy ions from proton to uranium with the energy up to -400 MeV/u and produce rare isotopes. These high purity, high intensity, and high energy beams generate the various secondary radiation which will impact on the shielding aspects of the main linear accelerator tunnels. In the main tunnel the secondary neutrons are produced by uniform beam-loss or accident criteria. In this paper evaluations of several source terms induced by beam-loss will be discussed along with the physics model of the Monte Carlo simulation codes. The beam-loss criteria were tested for the evaluation of source term for the main beam line tunnel of the RAON accelerator. It was found that the amount of the secondary neutrons depends on the incident angle of projectile on the beam pipe and the mass and energy of projectile. The influence of selected physics models and libraries of MCNPX and PHITS has been examined. The secondary neutrons were produced most in the CEM and LAQGSM model.

  4. Beam loss studies on silicon strip detector modules for the CMS experiment

    CERN Document Server

    Fahrer, Manuel

    2006-01-01

    The large beam energy of the LHC demands for a save beam abort system. Nevertheless, failures cannot be excluded with last assurance and are predicted to occur once per year. As the CMS experiment is placed in the neighboured LHC octant, it is affected by such events. The effect of an unsynchronized beam abort on the silicon strip modules of the CMS tracking detector has been investigated in this thesis by performing one accelerator and two lab experiments. The dynamical behaviour of operational parameters of modules and components has been recorded during simulated beam loss events to be able to disentangle the reasons of possible damages. The first study with high intensive proton bunches at the CERN PS ensured the robustness of the module design against beam losses. A further lab experiment with pulsed IR LEDs clarified the physical and electrical processes during such events. The silicon strip sensors on a module are protected against beam losses by a part of the module design that originally has not been...

  5. Propagation of Gaussian beam in longitudinally inhomogeneous nonlinear graded index waveguides with gain and losses

    CERN Document Server

    Yesayan, G L

    2001-01-01

    The equations for the width and curvature radius of the wave front for a Gaussian beam of light propagating along the axis of the longitudinally inhomogeneous graded index waveguide with gain and losses in the presence of third-order nonlinearity are obtained. By means of numerical calculations it is shown that in such waveguides the mode of stabilization of the beam width is possible, when the absorption of radiation on the edges of the beam compensates its spreading caused by the longitudinal inhomogeneity and nonlinearity of the waveguide

  6. System Architecture for measuring and monitoring Beam Losses in the Injector Complex at CERN

    CERN Document Server

    Zamantzas, C; Dehning, B; Jackson, S; Kwiatkowski, M; Vigano, W

    2012-01-01

    The strategy for beam setup and machine protection of the accelerators at the European Organisation for Nuclear Research (CERN) is mainly based on its Beam Loss Monitoring (BLM) systems. For their upgrade to higher beam energies and intensities, a new BLM system is under development with the aim of providing faster measurement updates with higher dynamic range and the ability to accept more types of detectors as input compared to its predecessors. In this paper, the architecture of the complete system is explored giving an insight to the design choices made to provide a highly reconfigurable system that is able to fulfil the different requirements of each accelerator using reprogrammable devices.

  7. Simulation of Heavy-Ion Beam Losses with the SixTrack-FLUKA Active Coupling

    CERN Document Server

    Hermes, Pascal; Cerutti, Francesco; Ferrari, Alfredo; Jowett, John; Lechner, Anton; Mereghetti, Alessio; Mirarchi, Daniele; Ortega, Pablo; Redaelli, Stefano; Salvachua, Belen; Skordis, Eleftherios; Valentino, Gianluca; Vlachoudis, Vasilis

    2016-01-01

    The LHC heavy-ion program aims to further increase the stored ion beam energy, putting high demands on the LHC collimation system. Accurate simulations of the ion collimation efficiency are crucial to validate the feasibility of new proposed configurations and beam parameters. In this paper we present a generalized framework of the SixTrack-FLUKA coupling to simulate the fragmentation of heavy-ions in the collimators and their motion in the LHC lattice. We compare heavy-ion loss maps simulated on the basis of this framework with the loss distributions measured during heavy-ion operation in 2011 and 2015.

  8. Beam-loss monitoring system with free-air ionization chambers

    Science.gov (United States)

    Nakagawa, H.; Shibata, S.; Hiramatsu, S.; Uchino, K.; Takashima, T.

    1980-08-01

    A monitoring system for proton beam losses was installed in the proton synchrotron at the National Laboratory for High Energy Physics in Japan (KEK). The system consists of 56 air ionization chambers (AIC) for radiation detectors, 56 integrators, 56 variable gain amplifiers, two multiplexers, a computer interface circuit, a manual controller and a high tension power supply. The characteristics of the AIC, time resolution, radiation measurement upper limit saturation, kinetic energy dependence of the sensitivity, chamber activation effect, the beam loss detection system and the results of observations with the monitoring system are described.

  9. Low loss power splitter for antenna beam forming networks using probes in a waveguide

    DEFF Research Database (Denmark)

    Dich, Mikael; Mortensen, Mette Dahl

    1994-01-01

    The design of a low loss one-to-four power splitter suitable for beam forming networks in antenna arrays is presented. The power splitter is constructed of a shorted waveguide in which five coaxial probes are inserted. Methods for the design of the power splitter are presented together with an ex......The design of a low loss one-to-four power splitter suitable for beam forming networks in antenna arrays is presented. The power splitter is constructed of a shorted waveguide in which five coaxial probes are inserted. Methods for the design of the power splitter are presented together...

  10. Special diagnostic methods and beam loss control on high intensity proton synchrotrons and storage rings Circular proton accelerator

    CERN Document Server

    Warsop, C M

    2002-01-01

    Two topics concerning high intensity, medium energy, circular proton accelerators have been studied: specialist diagnostics and beam loss control. The use of specially configured, low intensity diagnostic beams to help measure, understand and control high intensity beams is described. The ideas are developed and demonstrated on the ISIS 800 MeV, high intensity proton synchrotron at the Rutherford Appleton Laboratory in the UK. It is shown that these techniques make much new and valuable information available, which is particularly useful in achieving the precise beam optimisation required for low and controlled losses. Beam loss control in the proposed European Spallation Source (ESS) accumulator rings is studied. The expected losses are summarised, and a design for the beam collimation system presented. A new code for the simulation of loss control is outlined, and then used to test the collimation system under most foreseeable conditions. It is expected that the required loss control levels will be achievab...

  11. Modeling the response of a fast ion loss detector using orbit tracing techniques in a neutral beam prompt-loss study on the DIII-D tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Pace, D. C.; Heidbrink, W. W.; Muscatello, C. M.; Zhu, Y. B. [University of California-Irvine, Irvine, California 92697 (United States); Fisher, R. K.; Van Zeeland, M. A. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Garcia-Munoz, M. [Max-Planck-Institut fuer Plasmaphysik, Garching D-85748 (Germany); Darrow, D. S.; Nazikian, R. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451 (United States)

    2010-10-15

    A numerical model describing the expected measurements of neutral beam prompt-losses by a newly commissioned fast ion loss detector (FILD) in DIII-D is presented. This model incorporates the well understood neutral beam deposition profiles from all eight DIII-D beamlines to construct a prompt-loss source distribution. The full range of detectable ion orbit phase space available to the FILD is used to calculate ion trajectories that overlap with neutral beam injection footprints. Weight functions are applied to account for the level of overlap between these detectable orbits and the spatial and velocity (pitch) properties of ionized beam neutrals. An experimental comparison is performed by firing each neutral beam individually in the presence of a ramping plasma current. Fast ion losses determined from the model are in agreement with measured losses.

  12. E-beam-patterned hydrogels to control nanoscale surface bioactivity

    Science.gov (United States)

    Krsko, P.; Saaem, I.; Clancy, R.; Geller, H.; Soteropoulos, P.; Libera, M.

    2005-11-01

    We are interested in controlling the spatial distribution of proteins on surfaces at cellular and subcellular length scales. To do this, we use a variation of e-beam lithography in a field-emission scanning electron microscope (SEM) to radiation crosslink thin films of water- soluble polymers such as poly(ethylene glycol) [PEG] and poly (carboxylic acids). We can simultaneously pattern the resulting hydrogels on silicon or glass surfaces with nanoscale and microscale feature sizes. Using hydroxy-terminated PEG 6800 we create gels with swell ratios between unity and fifteen depending on the degree of radiation crosslinking, and the swelling properties can be interpreted in terms of the Flory-Rehner formulation modified for one-dimensional swelling. While lightly-crosslinked PEG gels resist protein adsorption and cell adhesion as expected, highly crosslinked PEG gels adsorb such proteins as fibronectin and laminin and consequently become adhesive to fibroblasts, macrophages, and neurons. By spatially modulating the degree of crosslinking, we can localize these cells on surfaces and, for example, direct neurite outgrowth. If instead of using hydroxy-terminated PEG we use amine- terminated PEG, we introduce the additional flexibility of creating high-swelling PEG gels that resist nonspecific protein adsorption but to which specific proteins can be covalently bound. These can be surface patterned at submicron spacings, and we can pattern 7500 nanohydrogels in a 100 micron diameter arrays in 10 seconds. This is an areal density ~104 times greater than a modern DNA/protein chip, and the required bioreagents for chip fabrication and processing are proportionately less. We can bind fibronectin and laminin to different arrays, and we show that these proteins maintain their biospecificity after binding to the nanohydrogels with high fidelity. Looking to applications in next-generation protein-chip technology, our most recent experiments compare the performance of nanohydrogel

  13. The Evaluation of the Residual Dose Caused by the Large-Angle Foil Scattering Beam Loss for the High Intensity Beam Operation in the J-PARC RCS

    Science.gov (United States)

    Kato, Shinichi; Yamamoto, Kazami; Harada, Hiroyuki; Hotchi, Hideaki; Saha, Pranab K.; Kinsho, Michikazu

    The Japan Proton Accelerator Research Complex 3-GeV rapid cycling synchrotron (RCS) has adopted the multi-turn charge-exchange injection scheme that uses H- beams. During injection, both the injected and circulating beams scatter from the charge-exchange foil. Therefore, the beam loss caused by the large-angle scattering from the foil occurs downstream of the injection point. For countermeasure against the uncontrolled beam loss, a new collimation system was developed and installed in the summer shutdown period in 2011. During beam commissioning, this uncontrolled beam loss was successfully localized for a 300 kW beam. Since the present target power of the RCS is 1 MW, the accurate simulation model to reproduce experimental results has been constructed in order to evaluate residual dose at higher power operation.

  14. Very Fast Losses of the Circulating LHC Beam, their Mitigation and Machine Protection

    CERN Document Server

    Baer, Tobias; Elsen, Eckhard

    The Large Hadron Collider (LHC) has a nominal energy of 362MJ stored in each of its two counter-rotating beams - over two orders of magnitude more than any previous accelerator and enough to melt 880kg of copper. Therefore, in case of abnormal conditions comprehensive machine protection systems extract the beams safely from the LHC within not more than three turns $\\approx$270$\\mu$s. The first years of LHC operation demonstrated a remarkable reliability of the major machine protection systems. However, they also showed that the LHC is vulnerable to losses of the circulating beams on very fast timescales, which are too fast to ensure an active protection. Very fast equipment failures, in particular of normal-conducting dipole magnets and the transverse damper can lead to such beam losses. Whereas these failures were already studied in the past, other unexpected beam loss mechanisms were observed after the LHC start-up: so-called (un)identified falling objects (UFOs), which are believed to be micrometer-sized m...

  15. An FPGA Based Implementation for Real-Time Processing of the LHC Beam Loss Monitoring System's Data

    CERN Document Server

    Dehning, B; Emery, J; Ferioli, G; Zamantzas, C

    2006-01-01

    The strategy for machine protection and quench prevention of the Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) is mainly based on the Beam Loss Monitoring (BLM) system. At each turn, there will be several thousands of data to record and process in order to decide if the beams should be permitted to continue circulating or their safe extraction is necessary to be triggered. The processing involves a proper analysis of the loss pattern in time and for the decision the energy of the beam needs to be accounted. This complexity needs to be minimized by all means to maximize the reliability of the BLM system and allow a feasible implementation. In this paper, a field programmable gate array (FPGA) based implementation is explored for the real-time processing of the LHC BLM data. It gives emphasis on the highly efficient Successive Running Sums (SRS) technique used that allows many and long integration periods to be maintained for each detector's data with relatively small leng...

  16. Multiple-electron losses in uranium ion beams in heavy ion synchrotrons

    Science.gov (United States)

    Bozyk, L.; Chill, F.; Litsarev, M. S.; Tolstikhina, I. Yu.; Shevelko, V. P.

    2016-04-01

    Charge changing processes as the result of collisions with residual gas particles are the main cause of beam loss in high energy medium charge state heavy ion beams. To investigate the magnitude of this effect for heavy ion synchrotrons like the planned SIS100 at GSI, the multiple-electron and the total electron-loss cross sections are calculated for Uq+ ions, q = 10, 28, 40, 73, colliding with typical gas components H2, He, C, N2, O2, and Ar at ion energies E = 1 MeV/u-10 GeV/u. The total electron-capture cross sections for U28+ and U73+ ions interacting with these gases are also calculated. Most of these cross sections are new and presented for the first time. Calculated charge-changing cross sections are used to determine the ion-beam lifetimes τ for U28+ ions which agree well with the recently measured values at SIS18/GSI in the energy range E = 10-200 MeV/u. Using simulations made by the StrahlSim code with the reference ion U28+, it is found that in SIS100 the beam loss caused by single and multiple electron losses has only little impact on the residual gas density due to the high efficiency of the ion catcher system.

  17. Enhanced relativistic-electron-beam energy loss in warm dense aluminum.

    Science.gov (United States)

    Vaisseau, X; Debayle, A; Honrubia, J J; Hulin, S; Morace, A; Nicolaï, Ph; Sawada, H; Vauzour, B; Batani, D; Beg, F N; Davies, J R; Fedosejevs, R; Gray, R J; Kemp, G E; Kerr, S; Li, K; Link, A; McKenna, P; McLean, H S; Mo, M; Patel, P K; Park, J; Peebles, J; Rhee, Y J; Sorokovikova, A; Tikhonchuk, V T; Volpe, L; Wei, M; Santos, J J

    2015-03-01

    Energy loss in the transport of a beam of relativistic electrons in warm dense aluminum is measured in the regime of ultrahigh electron beam current density over 2×10^{11}  A/cm^{2} (time averaged). The samples are heated by shock compression. Comparing to undriven cold solid targets, the roles of the different initial resistivity and of the transient resistivity (upon target heating during electron transport) are directly observable in the experimental data, and are reproduced by a comprehensive set of simulations describing the hydrodynamics of the shock compression and electron beam generation and transport. We measured a 19% increase in electron resistive energy loss in warm dense compared to cold solid samples of identical areal mass.

  18. Distributed beam loss monitor based on the Cherenkov effect in an optical fiber

    Science.gov (United States)

    Maltseva, Yu; Emanov, F. A.; Petrenko, A. V.; Prisekin, V. G.

    2015-05-01

    This review discusses a distributed beam loss monitor which is based on the Cherenkov effect in an optical fiber and which has been installed at the VEPP-5 Injection Complex at the Budker Institute of Nuclear Physics. The principle of the device operation consists in detecting the Cherenkov radiation generated in an optical fiber by relativistic charged particles that are produced in an electromagnetic shower when highly relativistic beam particles (electrons or positrons) hit the accelerator vacuum chamber wall. Our experiments used a photomultiplier tube (PMT) to detect the Cherenkov light. Knowing when the PMT signal arrives tells us where the beam loss occurs. Using a 20-m-long optical fiber allowed a detector spatial resolution of 3 m. The way to improve the resolution is to optimize the monitor working conditions and optical fiber and PMT parameters, potentially leading to a resolution of as fine as 0.5 m according to our estimates.

  19. Design and Development of a Diagnostics Client for a Beam Loss Measurement System at CERN

    CERN Document Server

    Angelogiannopoulos, Emmanouil; Jackson, Stephen

    The European Organization for Nuclear Research, known as CERN, is one of the biggest research centers in the field of particle physics. Its main function is to provide particle accelerators and other infrastructure needed for high energy physics research. Particles are accelerated through a complex of accelerators and are brought into collision, in order to study the fundamental elements of matter and the forces acting between them. Of course, such complex and expensive machines need control and protection. For that purpose, a variety of different systems -hardware and/or software- is needed. One such system is the Beam Loss Monitoring (BLM) system of an accelerator. This kind of system is designed for measuring beam losses around an accelerator. An appropriate design of the BLM system and an appropriate location of the monitors enable a wide field of very useful beam diagnostics and machine protection possibilities. This thesis focuses on the design and development of a client application, which is realized ...

  20. Hydrodynamic approach to surface pattern formation by ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Mario, E-mail: marioc@upcomillas.es [Grupo Interdisciplinar de Sistemas Complejos (GISC) and Grupo de Dinamica No Lineal (DNL), Escuela Tecnica Superior de Ingenieri a - ICAI, Universidad Pontificia Comillas, E-28015 Madrid (Spain); Cuerno, Rodolfo [Departamento de Matematicas and GISC, Universidad Carlos III de Madrid, Avenida de la Universidad 30, E-28911 Leganes (Spain)

    2012-02-15

    On the proper timescale, amorphous solids can flow. Solid flow can be observed macroscopically in glaciers or lead pipes, but it can also be artificially enhanced by creating defects. Ion Beam Sputtering (IBS) is a technique in which ions with energies in the 0.110 keV range impact against a solid target inducing defect creation and dynamics, and eroding its surface leading to formation of ordered nanostructures. Despite its technological interest, a basic understanding of nanopattern formation processes occurring under IBS of amorphizable targets has not been clearly established, recent experiments on Si having largely questioned knowledge accumulated during the last two decades. A number of interfacial equations have been proposed in the past to describe these phenomena, typically by adding together different contributions coming from surface diffusion, ion sputtering or mass redistribution, etc. in a non-systematic way. Here, we exploit the general idea of solids flowing due to ion impacts in order to establish a general framework into which different mechanisms (such as viscous flow, stress, diffusion, or sputtering) can be incorporated, under generic physical conservation laws. As opposed to formulating phenomenological interfacial equations, this approach allows to assess systematically the relevance and interplay of different physical mechanisms influencing surface pattern formation by IBS.

  1. Recommended Locations of Beam Loss Monitors for the ATLAS Roman Pots

    CERN Document Server

    Hall-Wilton, R J; Talanov, V

    2007-01-01

    This note suggests suitable locations to position beam loss monitors to observe losses on the ATLAS Roman Pot station located close to 240m from IP1. This monitoring is envisaged to help to avoid quenches of the super- conducting magnets downstream of the roman pots and to avert damage to either the LHC machine elements or the roman pot detectors. The results presented in this note indicate the locations where the BLMs should be installed. The recommended locations are determined using previous simulation results on BLM response to losses; therefore these results should be considered in conjunction with the previous results. A more detailed note on the topic will follow later.

  2. Recommended locations of beam-loss monitors for the ATLAS Roman pots

    CERN Document Server

    Hall-Wilton, R J; Talanov, V

    2007-01-01

    This note suggests suitable locations to position beam loss monitors to observe losses on the ATLAS Roman Pot station located close to 240m from IP1. This monitoring is envisaged to help to avoid quenches of the super- conducting magnets downstream of the roman pots and to avert damage to either the LHC machine elements or the roman pot detectors. The results presented in this note indicate the locations where the BLMs should be installed. The recommended locations are determined using previous simulation results on BLM response to losses; therefore these results should be considered in conjunction with the previous results. A more detailed note on the topic will follow later.

  3. Beam Loss Control for the Unstripped Ions from the PS2 Charge Exchange Injection

    CERN Document Server

    Bartmann, W; Benedikt, M; Goddard, B; Kramer, T; Papaphilippou, Y; Vincke, Hel

    2010-01-01

    Control of beam losses is an important aspect of the H-injection system for the PS2, a proposed replacement of the CPS in the CERN injector complex. H- ions may pass the foil unstripped or be partially stripped to excited H0 states which may be stripped in the subsequent strong-field chicane magnet. Depending on the choice of the magnetic field, atoms in the ground and first excited states can be extracted and dumped. The conceptual design of the waste beam handling is presented, including local collimation and the dump line, both of which must take into account the divergence of the beam from stripping in fringe fields. Beam load estimates and activation related requirements of the local collimators and dump are briefly discussed.

  4. Loss of balance during balance beam walking elicits a multifocal theta band electrocortical response.

    Science.gov (United States)

    Sipp, Amy R; Gwin, Joseph T; Makeig, Scott; Ferris, Daniel P

    2013-11-01

    Determining the neural correlates of loss of balance during walking could lead to improved clinical assessment and treatment for individuals predisposed to falls. We used high-density electroencephalography (EEG) combined with independent component analysis (ICA) to study loss of balance during human walking. We examined 26 healthy young subjects performing heel-to-toe walking on a treadmill-mounted balance beam as well as walking on the treadmill belt (both at 0.22 m/s). ICA identified clusters of electrocortical EEG sources located in or near anterior cingulate, anterior parietal, superior dorsolateral-prefrontal, and medial sensorimotor cortex that exhibited significantly larger mean spectral power in the theta band (4-7 Hz) during walking on the balance beam compared with treadmill walking. Left and right sensorimotor cortex clusters produced significantly less power in the beta band (12-30 Hz) during walking on the balance beam compared with treadmill walking. For each source cluster, we also computed a normalized mean time/frequency spectrogram time locked to the gait cycle during loss of balance (i.e., when subjects stepped off the balance beam). All clusters except the medial sensorimotor cluster exhibited a transient increase in theta band power during loss of balance. Cluster spectrograms demonstrated that the first electrocortical indication of impending loss of balance occurred in the left sensorimotor cortex at the transition from single support to double support prior to stepping off the beam. These findings provide new insight into the neural correlates of walking balance control and could aid future studies on elderly individuals and others with balance impairments.

  5. The LHC beam loss monitoring system's real-time data analysis card

    CERN Document Server

    Dehning, B; Ferioli, G; Guaglio, G; Leitner, R; Zamantzas, C

    2005-01-01

    The BLM (Beam Loss Monitoring) system has to prevent the superconducting magnets from being quenched and protect the machine components against damages making it one of the most critical elements for the protection of the LHC. The complete system consists of 3600 detectors, placed at various locations around the ring, tunnel electronics, which are responsible for acquiring, digitizing, and transmitting the data, and surface electronics, which receive the data via 2km optical data links, process, analyze, store, and issue warning and abort triggers. At those surface units, named BLMTCs, the backbone on each of them is an FPGA (field programmable gate array) which treats the loss signals collected from 16 detectors. It takes into account the beam energy and keeps 192 running sums giving loss durations of up to the last 84 seconds before it compares them with thresholds uniquely programmable for each detector. In this paper, the BLMTC's design is explored giving emphasis to the strategies followed in combining t...

  6. Evaluation of Beam Losses and Energy Depositions for a Possible Phase II Design for LHC Collimation

    CERN Document Server

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

    2008-01-01

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

  7. Simulation of the ATLAS SCT barrel module response to LHC beam loss scenarios

    CERN Document Server

    Rose, P; The ATLAS collaboration; Fadeyev, V; Spencer, E; Wilder, M; Domingo, M

    2014-01-01

    In the event of beam loss at the LHC, ATLAS Inner Detector components nearest the beam line may be subjected to unusually large amounts of radiation. Understanding their behavior in such an event is important in determining whether they would still function properly. We built a SPICE model of the silicon strip module electrical system to determine the behavior of its elements during a realistic beam loss scenario. We found that the power supply and bias filter characteristics strongly affect the module response in such scenarios. In particular, the following self-limiting phenomena were observed: there is a finite amount of charge initially available on the bias filter capacitors for collection by the strips; the power supply current limit reduces the rate at which the bias filter capacitors' charge can be replenished; the reduced bias voltage leads to a smaller depletion depth in the sensors which results in less collected charge. These effects provide a larger measure of safety during beam loss events than ...

  8. Background gas density and beam losses in NIO1 beam source

    Science.gov (United States)

    Sartori, E.; Veltri, P.; Cavenago, M.; Serianni, G.

    2016-02-01

    NIO1 (Negative Ion Optimization 1) is a versatile ion source designed to study the physics of production and acceleration of H- beams up to 60 keV. In ion sources, the gas is steadily injected in the plasma source to sustain the discharge, while high vacuum is maintained by a dedicated pumping system located in the vessel. In this paper, the three dimensional gas flow in NIO1 is studied in the molecular flow regime by the Avocado code. The analysis of the gas density profile along the accelerator considers the influence of effective gas temperature in the source, of the gas temperature accommodation by collisions at walls, and of the gas particle mass. The calculated source and vessel pressures are compared with experimental measurements in NIO1 during steady gas injection.

  9. Background gas density and beam losses in NIO1 beam source

    Energy Technology Data Exchange (ETDEWEB)

    Sartori, E., E-mail: emanuele.sartori@igi.cnr.it; Veltri, P.; Serianni, G. [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova (Italy); Cavenago, M. [INFN-LNL, v.le dell’Università 2, I-35020 Legnaro (PD) (Italy)

    2016-02-15

    NIO1 (Negative Ion Optimization 1) is a versatile ion source designed to study the physics of production and acceleration of H- beams up to 60 keV. In ion sources, the gas is steadily injected in the plasma source to sustain the discharge, while high vacuum is maintained by a dedicated pumping system located in the vessel. In this paper, the three dimensional gas flow in NIO1 is studied in the molecular flow regime by the Avocado code. The analysis of the gas density profile along the accelerator considers the influence of effective gas temperature in the source, of the gas temperature accommodation by collisions at walls, and of the gas particle mass. The calculated source and vessel pressures are compared with experimental measurements in NIO1 during steady gas injection.

  10. Beam-size effect and particle losses at Super$B$ factory developed in Italy

    CERN Document Server

    Kotkin, G L

    2009-01-01

    In the colliders, the macroscopically large impact parameters give a substantial contribution to the standard cross section of the $e^+ e^- \\to e^+ e^- \\gamma$ process. These impact parameters may be much larger than the transverse sizes of the colliding bunches. It means that the standard cross section of this process has to be substantially modified. In the present paper such a beam-size effect is calculated for bremsstrahlung at Super$B$ factory developed in Italy. We find out that this effect reduces beam losses due to bremsstrahlung by about 40%.

  11. Beam-size effect and particle losses at B-factories KEKB and PEP-II

    Energy Technology Data Exchange (ETDEWEB)

    Kotkin, G.L.; Serbo, V.G. E-mail: serbo@math.nsc.ru

    2005-01-01

    In the colliders, the macroscopically large impact parameters give a substantial contribution to the standard cross section of the e{sup +}e{sup -}{yields}e{sup +}e{sup -}{gamma} process. These impact parameters may be much larger than the transverse sizes of the colliding bunches. It means that the standard cross section of this process has to be substantially modified. In the present paper such a beam-size effect is calculated for bremsstrahlung at B-factories KEKB and PEP-II. We find out that this effect reduces beam losses due to bremsstrahlung by about 20%.

  12. Test of Different Beam Loss Detectors at the GSI Heavy Ion Synchrotron

    CERN Document Server

    Forck, P

    2001-01-01

    For the sensitive process of slow extraction from a synchrotron a reliable control of the beam losses is needed. We have tested several types of particle detectors mounted at the extraction path of the SIS: A BF-tube for pure neutron detection, a liquid and a plastic scintillator detecting neutrons, gammas and charged particles and an Argon filled ionization chamber mainly sensitive to charged particles. While the count rate is quite different, the time evolution of all detector signals during the spill are similar, but the plastic scintillator has the highest dynamic range. This type is going to be used for beam alignment.

  13. Patterns and drivers of scattered tree loss in agricultural landscapes

    DEFF Research Database (Denmark)

    Plieninger, Tobias; Levers, Christian; Mantel, Martin;

    2015-01-01

    of high nature conservation value) for a region in Southwestern Germany for the 1968 2009 period and to identify the driving forces of this decline. We derived orchard meadow loss from 1968 and 2009 aerial images and used a boosted regression trees modelling framework to assess the relative importance...... of 18 environmental, demographic, and socio-economic variables to test five alternative hypothesis explaining orchard meadow loss. We found that orchard meadow loss occurred in flatter areas, in areas where smaller plot sizes and fragmented orchard meadows prevailed, and in areas near settlements...

  14. From amorphous speckle pattern to reconfigurable Bessel beam via wavefront shaping

    CERN Document Server

    Di Battista, Diego; Leonetti, Marco; Zacharakis, Giannis

    2015-01-01

    Bessel beams are non-diffracting light structures, which can be produced with simple tabletop optical elements such as axicon lenses or ring spatial filters and coherent laser beams. One of their main characteristic is that Bessel beams maintain their spatial characteristics after meters of propagation. In this paper we demonstrate a system and method for generating Bessel beams from amorphous speckle patterns, exploiting adaptive optimization by a spatial light modulator. These speckles are generated by light modes transmitted through a scattering curtain and selected by a ring shaped filter. With the proposed strategy it is possible to produce at user defined positions, reconfigurable, non-diffracting Bessel beams through a disordered medium.

  15. Controlled Transverse Blow-up of Highenergy Proton Beams for Aperture Measurements and Loss Maps

    CERN Document Server

    Hӧfle, W; Redaelli, S; Schmidt, R; Valuch, D; Wollmann, D; Zerlauth, M

    2012-01-01

    A technique was developed to blow-up transversely in a controlled way high energy proton beams in the LHC. The technique is based on band limited white noise excitation that is injected into the transverse damper feedback loop. The injected signal can be gated to selectively blow-up individual trains of bunches. The speed of transverse blow-up can be precisely controlled. This opens the possibility to perform safely and efficiently aperture measurements and loss maps with high intensity bunch trains well above stored beam energies that are considered to be safe. In particular, lengthy procedures for measurements at top energy, otherwise requiring multiple fills of individual bunches, can be avoided. In this paper, the method is presented and results from beam measurements are discussed and compared with alternative blowup methods.

  16. A Gigabit Ethernet link for an FPGA based Beam Loss Measurement System

    CERN Document Server

    Kwiatkowski, M; Dehning, B; Vigano, W; Zamantzas, C

    2013-01-01

    A new Beam Loss Monitoring (BLM) system is under development at the European Organisation for Nuclear Research (CERN) within the LHC Injector Upgrade (LIU) project. The multi-channel system will have the ability to measure beam losses from various types of detectors with high precision and wide dynamic range. Several modes of data acquisition are supported. The data rate in the singlechannel mode is 16 Mbps and in the multi-channel mode 128 Mbps. The Gigabit Ethernet link is implemented in an FPGA, which allows both a high throughput and a quick validation of the digital data processing algorithms using standard PCs in the initial stages of the development. Both TCP and UDP protocols were explored. The implementation of the Ethernet link is flexible and proved to be highly reliable, leading to its planned use in other measurement systems developed at CERN. The implementation details of the Ethernet link and the results achieved will be described in this paper.

  17. Reducing the extraction loss via laser notching the H- beam at the Booster injection revolution frequency

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xi; Ankenbrandt, Charles M.; /Fermilab

    2005-05-01

    With the requirement for more protons per hour from Booster, the radiation is a limiting factor. Laser notching the H{sup -} beam at the Booster injection revolution frequency and properly aligning those notches on top of each other at the injection and relative to the trigger of firing extraction kickers can remove most of the extraction loss caused by the slow rise time of the kicker field.

  18. Reliability of the Beam Loss Monitors System for the Large Hadron Collider at CERN

    CERN Document Server

    Guaglio, G; Santoni, C

    2005-01-01

    The energy stored in the Large Hadron Collider is unprecedented. The impact of the beam particles can cause severe damage on the superconductive magnets, resulting in significant downtime for repairing. The Beam Loss Monitors System (BLMS) detects the secondary particles shower of the lost beam particles and initiates the extraction of the beam before any serious damage to the equipment can occur. This thesis defines the BLMS specifications in term of reliability. The main goal is the design of a system minimizing both the probability to not detect a dangerous loss and the number of false alarms generated. The reliability theory and techniques utilized are described. The prediction of the hazard rates, the testing procedures, the Failure Modes Effects and Criticalities Analysis and the Fault Tree Analysis have been used to provide an estimation of the probability to damage a magnet, of the number of false alarms and of the number of generated warnings. The weakest components in the BLMS have been pointed out....

  19. High resolution acoustic measurement system and beam pattern reconstruction method for bat echolocation emissions.

    Science.gov (United States)

    Gaudette, Jason E; Kloepper, Laura N; Warnecke, Michaela; Simmons, James A

    2014-01-01

    Measurements of the transmit beam patterns emitted by echolocating bats have previously been limited to cross-sectional planes or averaged over multiple signals using sparse microphone arrays. To date, no high-resolution measurements of individual bat transmit beams have been reported in the literature. Recent studies indicate that bats may change the time-frequency structure of their calls depending on the task, and suggest that their beam patterns are more dynamic than previously thought. To investigate beam pattern dynamics in a variety of bat species, a high-density reconfigurable microphone array was designed and constructed using low-cost ultrasonic microphones and custom electronic circuitry. The planar array is 1.83 m wide by 1.42 m tall with microphones positioned on a 2.54 cm square grid. The system can capture up to 228 channels simultaneously at a 500 kHz sampling rate. Beam patterns are reconstructed in azimuth, elevation, and frequency for visualization and further analysis. Validation of the array measurement system and post-processing functions is shown by reconstructing the beam pattern of a transducer with a fixed circular aperture and comparing the result with a theoretical model. To demonstrate the system in use, transmit beam patterns of the big brown bat, Eptesicus fuscus, are shown.

  20. Simulation of the ATLAS SCT Barrel Module Response to LHC Beam Loss Scenarios

    CERN Document Server

    Rose, P; The ATLAS collaboration; Fadeyev, V; Spencer, E; Wilder, M; Domingo, M

    2013-01-01

    In the event of beam loss at the LHC, ATLAS Inner Detector components nearest the beamline may be subjected to unusually large amounts of radiation. Understanding their behavior in such an event is important in determining whether they would still function properly. We built a SPICE model of the silicon strip module electrical system to determine the behavior of its elements during a realistic beam loss scenario. We found that the power supply and bias filter characteristics strongly affect the module response in such scenarios. In particular, the following self-limiting phenomena were observed: there is a finite amount of charge initially available on the bias filter capacitors for collection by the strips; the power supply current limit reduces the rate at which the bias filter capacitors' charge can be replenished; the reduced bias voltage leads to a smaller depletion depth which results in less collected charge. These effects provide a larger measure of safety during beam loss events than we have previous...

  1. Ultrashort pulse laser patterning of indium tin oxide thin films on glass by uniform diffractive beam patterns

    Energy Technology Data Exchange (ETDEWEB)

    Kuang Zheng, E-mail: z.kuang@liv.ac.uk [Laser Group, School of Engineering, University of Liverpool, Brownlow Street, Liverpool L69 3GQ (United Kingdom); Perrie, Walter; Liu Dun; Fitzsimons, Paul; Edwardson, Stuart P.; Fearon, Eamonn; Dearden, Geoff; Watkins, Ken G. [Laser Group, School of Engineering, University of Liverpool, Brownlow Street, Liverpool L69 3GQ (United Kingdom)

    2012-07-15

    In the last decade, indium tin oxide (ITO) has been most commonly employed to create transparent conducting oxides (TCOs) thin films for many industrial applications. It is usually necessary to pattern ITO thin films to create functional structures for specific applications. Direct-write micro-patterning of ITO thin films by ultra-short pulse lasers has demonstrated high quality without requiring multiple processing stations, compared with conventional patterning technologies (e.g. wet-etch lithography). However, the processing efficiency and throughput with a single beam can be insufficient because of the high level of attenuation needed for the output to meet the required 'thermal-free' parameters. In this paper, high throughput surface direct micro-structuring of ITO on glass is demonstrated by parallel processing using diffractive multiple ultrashort pulse laser beams ({lambda} = 1064 nm, {tau}p = 10 ps). By avoiding periodic and symmetrical geometry design, the diffractive multiple beam pattern generated by a spatial light modulator has high uniformity (the energy variation between each diffractive beam is <9%). The ITO thin film is removed by laser ablation of 25 identical beams at the same time without any damage to the glass substrate. Additionally, by synchronizing a scanning galvanometer, the processing demonstrates high flexibility to generate various surface patterns.

  2. Study of Young's double slit interference pattern from a Laguerre Gaussian beam

    CERN Document Server

    Emile, olivier

    2013-01-01

    The interference pattern of a Laguerre Gaussian beam in a double slit experiment is reported. Whereas a typical laser beam phase front is planar, a Laguerre Gaussian beam exhibits a wave front that is twisting along the direction of propagation. This leads to a distorted interference pattern. The topological charge also called the order of the twisted beam can be then readily and simply determined. More precisely, the naked eye resolution of the distortion shift of the interference pattern directly informs about the number of twists made as well as on the sign of the twist. These results are in very good agreement with theoretical calculations that offer a general description of the double slit interference with twisted beams.

  3. Beam filling loss adjustments for ASR-9 weather channel reflectivity estimates

    Science.gov (United States)

    Engholm, Cynthia D.; Troxel, Seth W.

    1990-10-01

    The FAA is deploying over 100 new airport surveillance radars (ASR-9) across the country. In contrast to earlier ASRs, the ASR-9 utilizes a separate digital weather processing channel to provide air traffic controllers with timely, calibrated displays of precipitation intensity. The ASR-9 utilizes dual selectable fan shaped elevation beams designed to track aircraft over a large volume. As a consequence, weather echoes received from these fan shaped beams represent vertically averaged quantities. If the precipitation only partially or nonuniformly fills the beam, then the vertically integrated reflectivity may underestimate the actual intensity of the storm. The ASR-9 weather channel corrects for this by adjusting the range dependent six level reflectivity thresholds. The appropriateness of the currently implemented correction has not been carefully examined and may require modification to take into account regional and morphological variability in storm structure. The method used to derive new beam filling loss adjustments is discussed. An extensive database of volumetric pencil beam radar data were used in conjunction with the ASR-9 simulation facility to derive adjustments aimed at calibrating the precipitation intensity reports to the maximum perceived hazard. Results from this calibration indicate that a single correction is appropriate for all sites and intensities. The new corrections yield substantially improved results over the current corrections in producing these reflectivity reports.

  4. Biodiversity loss decreases parasite diversity: theory and patterns.

    Science.gov (United States)

    Lafferty, Kevin D

    2012-10-19

    Past models have suggested host-parasite coextinction could lead to linear, or concave down relationships between free-living species richness and parasite richness. I explored several models for the relationship between parasite richness and biodiversity loss. Life cycle complexity, low generality of parasites and sensitivity of hosts reduced the robustness of parasite species to the loss of free-living species diversity. Food-web complexity and the ordering of extinctions altered these relationships in unpredictable ways. Each disassembly of a food web resulted in a unique relationship between parasite richness and the richness of free-living species, because the extinction trajectory of parasites was sensitive to the order of extinctions of free-living species. However, the average of many disassemblies tended to approximate an analytical model. Parasites of specialist hosts and hosts higher on food chains were more likely to go extinct in food-web models. Furthermore, correlated extinctions between hosts and parasites (e.g. if parasites share a host with a specialist predator) led to steeper declines in parasite richness with biodiversity loss. In empirical food webs with random removals of free-living species, the relationship between free-living species richness and parasite richness was, on average, quasi-linear, suggesting biodiversity loss reduces parasite diversity more than previously thought.

  5. Biodiversity loss decreases parasite diversity: theory and patterns

    Science.gov (United States)

    Lafferty, Kevin D.

    2012-01-01

    Past models have suggested host–parasite coextinction could lead to linear, or concave down relationships between free-living species richness and parasite richness. I explored several models for the relationship between parasite richness and biodiversity loss. Life cycle complexity, low generality of parasites and sensitivity of hosts reduced the robustness of parasite species to the loss of free-living species diversity. Food-web complexity and the ordering of extinctions altered these relationships in unpredictable ways. Each disassembly of a food web resulted in a unique relationship between parasite richness and the richness of free-living species, because the extinction trajectory of parasites was sensitive to the order of extinctions of free-living species. However, the average of many disassemblies tended to approximate an analytical model. Parasites of specialist hosts and hosts higher on food chains were more likely to go extinct in food-web models. Furthermore, correlated extinctions between hosts and parasites (e.g. if parasites share a host with a specialist predator) led to steeper declines in parasite richness with biodiversity loss. In empirical food webs with random removals of free-living species, the relationship between free-living species richness and parasite richness was, on average, quasi-linear, suggesting biodiversity loss reduces parasite diversity more than previously thought.

  6. Pilot Beam Pattern Design for Channel Estimation in Massive MIMO Systems

    Science.gov (United States)

    Noh, Song; Zoltowski, Michael D.; Sung, Youngchul; Love, David J.

    2014-10-01

    In this paper, the problem of pilot beam pattern design for channel estimation in massive multiple-input multiple-output systems with a large number of transmit antennas at the base station is considered, and a new algorithm for pilot beam pattern design for optimal channel estimation is proposed under the assumption that the channel is a stationary Gauss-Markov random process. The proposed algorithm designs the pilot beam pattern sequentially by exploiting the properties of Kalman filtering and the associated prediction error covariance matrices and also the channel statistics such as spatial and temporal channel correlation. The resulting design generates a sequentially-optimal sequence of pilot beam patterns with low complexity for a given set of system parameters. Numerical results show the effectiveness of the proposed algorithm.

  7. The applications of in situ electron energy loss spectroscopy to the study of electron beam nanofabrication.

    Science.gov (United States)

    Chen, Shiahn J; Howitt, David G; Gierhart, Brian C; Smith, Rosemary L; Collins, Scott D

    2009-06-01

    An in situ electron energy loss spectroscopy (EELS) technique has been developed to investigate the dynamic processes associated with electron-beam nanofabrication on thin membranes. In this article, practical applications germane to e-beam nanofabrication are illustrated with a case study of the drilling of nanometer-sized pores in silicon nitride membranes. This technique involves successive acquisitions of the plasmon-loss and the core-level ionization-loss spectra in real time, both of which provide the information regarding the hole-drilling kinetics, including two respective rates for total mass loss, individual nitrogen and silicon element depletion, and the change of the atomic bonding environment. In addition, the in situ EELS also provides an alternative method for endpoint detection with a potentially higher time resolution than by imaging. On the basis of the time evolution of in situ EELS spectra, a qualitative working model combining knock-on sputtering, irradiation-induced mass transport, and phase separation can be proposed.

  8. Extinction rates under nonrandom patterns of habitat loss

    OpenAIRE

    Seabloom, Eric W.; Dobson, Andy P.; Stoms, David M.

    2002-01-01

    Most models that examine the effects of habitat conversion on species extinctions assume that habitat conversion occurs at random. This assumption allows predictions about extinction rates based on the species–area relationship. We show that the spatially aggregated nature of habitat conversion introduces a significant bias that may lead species-loss rates to exceed those predicted by species–area curves. Correlations between human activity and major compositional gradients, or species richne...

  9. Thinning Hair and Hair Loss: Could it be Female Pattern Hair Loss?

    Science.gov (United States)

    ... effective treatment for FPHL. Supplements: Many supplements, including biotin and folic acid, are said to help grow ... that the supplement helps regrow hair. Hair loss shampoos: These shampoos tend to do one of the ...

  10. Quench Tests of LHC Magnets with Beam: Studies on Beam Loss development and determination of Quench levels

    CERN Document Server

    Priebe, A; Sapinski, M

    The application of superconducting materials in the field of high energy accelerator physics not only opens the doors to the generation of the magnetic fields unattainable to normal conductors but also demands facing new challenges. A transition fromthe superconducting state, which is characterized by a resistance-free flow of the electric current, to the normal conducting state is called quenching. This process might be extremely dangerous and even lead to destruction of amagnet superconducting coil if no protecting actions are taken. Therefore, the knowledge of a magnet quench level, i.e. amount of energy which causes the transition to the resistive state, is crucial for the safety and operational efficiency of the accelerator. Regarding that, specific thresholds are incorporated to dedicated quench prevention systems in order to suppress the origin of detected energy perturbation, for example beam losses, or mitigate the consequences of the quenching process by dissipating the energy stored in the magnetic...

  11. Prestress Loss and Bending Capacity of Pre-cracked 40 Year-Old PC Beams Exposed to Marine Environment

    Directory of Open Access Journals (Sweden)

    Dasar Amry

    2016-01-01

    Full Text Available Six prestressed concrete beams (PC beam were used for evaluation, consist of four post-tension beams (PC-O and two pre-tension beams (PC-R. In order to investigate the effect of crack on prestress loss and bending capacity after long-term exposed, prestressed concrete beams were pre-crack and then exposed to marine environment. Experimental work was carried out to evaluate PC beams performance after long-term exposed. In addition, visual observations and load bearing capacity test was carried out. Furthermore, evaluation of prestress loss conducted using three-point loading bending test and the remaining tendon forces in the beam were determined using Crack Re-opening Method. The experimental results revealed that prestress loss was increased due to corrosion of strand/wire which affected by the pre-crack on the prestressed beams. Approximately a prestress loss around 26% and 30% was recorded for post-tension and pre-tension beams respectively.

  12. Wetland loss patterns and inundation-productivity relationships prognosticate widespread salt marsh loss for southern New England

    Science.gov (United States)

    Tidal salt marsh is a key defense against, yet is especially vulnerable to, the effects of accelerated sea level rise. To determine whether salt marshes in southern New England will be stable given increasing inundation over the coming decades, we examined current loss patterns, ...

  13. Analysis of SubRamsey Patterns in Cesium Beam Frequency Standards

    Institute of Scientific and Technical Information of China (English)

    CHEN Jingbiao; WANG Fengzhi; YANG Donghai; WANG Yiqiu

    2001-01-01

    Using a precise probability expres-sion under excessive microwave power condition, theRamsey patterns in a cesium atomic beam frequencystandard with Ramsey separated oscillating fields havebeen carefully analyzed by numerical method. TwosubRamsey patterns are produced on both sides ofthe central Ramsey pattern. All factors, including mi-crowave power, excitation region length, drift regionlength and atomic velocity distribution, which affectthe subRamsey pattern have been analyzed, and someexplanations coming from approximated theory havebeen corrected in this paper.

  14. Design of a bullet beam pattern of a micro ultrasound transducer (Conference Presentation)

    Science.gov (United States)

    Roh, Yongrae; Lee, Seongmin

    2016-04-01

    Ultrasonic imaging transducer is often required to compose a beam pattern of a low sidelobe level and a small beam width over a long focal region to achieve good image resolution. Normal ultrasound transducers have many channels along its azimuth, which allows easy formation of the sound beam into a desired shape. However, micro-array transducers have no control of the beam pattern along their elevation. In this work, a new method is proposed to manipulate the beam pattern by using an acoustic multifocal lens and a shaded electrode on top of the piezoelectric layer. The shading technique split an initial uniform electrode into several segments and combined those segments to compose a desired beam pattern. For a given elevation width and frequency, the optimal pattern of the split electrodes was determined by means of the OptQuest-Nonlinear Program (OQ-NLP) algorithm to achieve the lowest sidelobe level. The requirement to achieve a small beam width with a long focal region was satisfied by employing an acoustic lens of three multiple focuses. Optimal geometry of the multifocal lens such as the radius of curvature and aperture diameter for each focal point was also determined by the OQ-NLP algorithm. For the optimization, a new index was devised to evaluate the on-axis response: focal region ratio = focal region / minimum beam width. The larger was the focal region ratio, the better was the beam pattern. Validity of the design has been verified through fabricating and characterizing an experimental prototype of the transducer.

  15. Improving the Fermilab Booster Notching Efficiency, Beam Losses and Radiation Levels

    CERN Document Server

    Rakhno, I L; Mokhov, N V; Sidorov, V I; Tropin, I S

    2012-01-01

    Currently a fast vertical 1.08-m long kicker (notcher) located in the Fermilab Booster Long-5 straight section is used to remove 3 out of 84 circulating bunches after injection to generate an abort gap. With magnetic field of 72.5 Gauss it removes only 87% of the 3-bunch intensity at 400 MeV, with 75% loss on pole tips of the focusing Booster magnets, 11% on the Long-6 collimators, and 1% in the rest of the ring. We propose to improve the notching efficiency and reduce beam loss in the Booster by using two horizontal kickers in the Long-12 section. The STRUCT calculations show that using such horizontal notchers, one can remove up to 99% of the 3-bunch intensity at 400-700 MeV, directing 96% of it to a new beam dump at the Long-13 section. This fully decouples notching and collimation. The beam dump absorbs most of the impinging proton energy in its jaws. The latter are encapsulated into an appropriate radiation shielding that reduces impact on the machine components, personnel and environment to the tolerabl...

  16. Polarization pattern of vector vortex beams generated by q-plates with different topological charges.

    Science.gov (United States)

    Cardano, Filippo; Karimi, Ebrahim; Slussarenko, Sergei; Marrucci, Lorenzo; de Lisio, Corrado; Santamato, Enrico

    2012-04-01

    We describe the polarization topology of the vector beams emerging from a patterned birefringent liquid crystal plate with a topological charge q at its center (q-plate). The polarization topological structures for different q-plates and different input polarization states have been studied experimentally by measuring the Stokes parameters point-by-point in the beam transverse plane. Furthermore, we used a tuned q=1/2-plate to generate cylindrical vector beams with radial or azimuthal polarizations, with the possibility of switching dynamically between these two cases by simply changing the linear polarization of the input beam.

  17. Polarization pattern of vector vortex beams generated by $q$-plates with different topological charges

    CERN Document Server

    Cardano, Filippo; Slussarenko, Sergei; Marrucci, Lorenzo; de Lisio, Corrado; Santamato, Enrico

    2012-01-01

    We describe the polarization topology of the vector beams emerging from a patterned birefringent liquid crystal plate with a topological charge $q$ at its center ($q$-plate). The polarization topological structures for different $q$-plates and different input polarization states have been studied experimentally by measuring the Stokes parameters point-by-point in the beam transverse plane. Furthermore, we used a tuned $q=1/2$-plate to generate cylindrical vector beams with radial or azimuthal polarizations, with the possibility of switching dynamically between these two cases by simply changing the linear polarization of the input beam.

  18. Generation of Homogeneous and Patterned Electron Beams using a Microlens Array Laser-Shaping Technique

    Energy Technology Data Exchange (ETDEWEB)

    Halavanau, Aliaksei [NICADD, DeKalb; Edstrom, Dean [Fermilab; Gai, Wei [Argonne, HEP; Ha, Gwanghui [Argonne, HEP; Piot, Philippe [NICADD, DeKalb; Power, John [Argonne, HEP; Qiang, Gao [Unlisted, CN; Ruan, Jinhao [Fermilab; Santucci, James [Fermilab; Wisniewski, Eric [Argonne, HEP

    2016-06-01

    In photocathodes the achievable electron-beam parameters are controlled by the laser used to trigger the photoemission process. Non-ideal laser distribution hampers the final beam quality. Laser inhomogeneities, for instance, can be "amplified" by space-charge force and result in fragmented electron beams. To overcome this limitation laser shaping methods are routinely employed. In the present paper we demonstrate the use of simple microlens arrays to dramatically improve the transverse uniformity. We also show that this arrangement can be used to produce transversely-patterned electron beams. Our experiments are carried out at the Argonne Wakefield Accelerator facility.

  19. Patterns and drivers of scattered tree loss in agricultural landscapes

    DEFF Research Database (Denmark)

    Plieninger, Tobias; Levers, Christian; Mantel, Martin

    2015-01-01

    Scattered trees support high levels of farmland biodiversity and ecosystem services in agricultural landscapes, but they are threatened by agricultural intensification, urbanization, and land abandonment. This study aimed to map and quantify the decline of orchard meadows (scattered fruit trees...... of high nature conservation value) for a region in Southwestern Germany for the 1968 2009 period and to identify the driving forces of this decline. We derived orchard meadow loss from 1968 and 2009 aerial images and used a boosted regression trees modelling framework to assess the relative importance...

  20. Synthesis of Pt nanoparticles and their burrowing into Si due to synergistic effects of ion beam energy losses

    Directory of Open Access Journals (Sweden)

    Pravin Kumar

    2014-10-01

    Full Text Available We report the synthesis of Pt nanoparticles and their burrowing into silicon upon irradiation of a Pt–Si thin film with medium-energy neon ions at constant fluence (1.0 × 1017 ions/cm2. Several values of medium-energy neon ions were chosen in order to vary the ratio of the electronic energy loss to the nuclear energy loss (Se/Sn from 1 to 10. The irradiated films were characterized using Rutherford backscattering spectroscopy (RBS, atomic force microscopy (AFM, scanning electron microscopy (SEM, X-ray diffraction (XRD and high resolution transmission electron microscopy (HRTEM. A TEM image of a cross section of the film irradiated with Se/Sn = 1 shows ≈5 nm Pt NPs were buried up to ≈240 nm into the silicon. No silicide phase was detected in the XRD pattern of the film irradiated at the highest value of Se/Sn. The synergistic effect of the energy losses of the ion beam (molten zones are produced by Se, and sputtering and local defects are produced by Sn leading to the synthesis and burrowing of Pt NPs is evidenced. The Pt NP synthesis mechanism and their burrowing into the silicon is discussed in detail.

  1. Stochastic orbit loss of neutral beam ions from NSTX due to toroidal Alfvén eigenmode avalanches

    Energy Technology Data Exchange (ETDEWEB)

    Darrow, D. S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Crocker, N. [Univ. of California, Los Angeles, CA (United States). Dept. of Physics; Fredrickson, E. D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Gorelenkov, N. N. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Gorelenkova, M. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Kubota, S. [Univ. of California, Los Angeles, CA (United States). Dept. of Physics; Medley, S. S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Podestà, M. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Shi, L. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); White, R. B. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

    2012-12-17

    Short toroidal Alfvén eigenmode (TAE) avalanche bursts in the National Spherical Torus Experiment (NSTX) cause a drop in the neutron rate and could also cause a loss of neutral beam ions at or near the full injection energy over an extended range of pitch angles. The simultaneous loss of wide ranges of pitch angle suggests stochastic transport of the beam ions takes place. When beam ion orbits are followed with a guiding centre code that incorporates the plasma's magnetic equilibrium plus the measured modes, the predicted ranges of lost pitch angle are like those seen in the experiment, with distinct populations of trapped and passing orbits lost. These correspond to domains where the stochasticity extends in the orbit phase space from the region of beam ion deposition to the loss boundary and the trajectories along which modes may transport particles extend from the deposition volume to the loss boundary.

  2. Beam-size effect and particle losses at SuperB factory developed in Italy

    Energy Technology Data Exchange (ETDEWEB)

    Kotkin, G L; Serbo, V G [Novosibirsk State University, 630090, Novosibirsk, Pirogova st., 2 (Russian Federation)], E-mail: serbo@math.nsc.ru

    2009-06-15

    In the colliders, the macroscopically large impact parameters give a substantial contribution to the standard cross section of the e{sup +}e{sup -}{yields} e{sup +}e{sup -}{gamma} process. These impact parameters may be much larger than the transverse sizes of the colliding bunches. It means that the standard cross section of this process has to be substantially modified. In the present paper such a beam-size effect is calculated for bremsstrahlung at SuperB factory developed in Italy. We find out that this effect reduces beam losses due to bremsstrahlung by about 40%. We perform a critical comparison of our result with that presented in the Conceptual Design Report of the Italian SuperB factory.

  3. Investigating the effect of electron emission pattern on RF gun beam quality

    Energy Technology Data Exchange (ETDEWEB)

    Rajabi, A. [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of); Shokri, B., E-mail: b-shokri@sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of); Physics Department, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of)

    2016-05-11

    Thermionic radio frequency gun is one of the most promising choices to gain a high quality electron beam, used in the infrared free electron lasers and synchrotron radiation injectors. To study the quality of the beam in a compact electron source, the emission pattern effect on the beam dynamics should be investigated. In the presented work, we developed a 3D simulation code to model the real process of thermionic emission and to investigate the effect of emission pattern, by considering geometrical constraints, on the beam dynamics. According to the results, the electron bunch emittance varies considerably with the emission pattern. Simulation results have been validated via comparison with the well-known simulation codes such as ASTRA simulation code and CST microwave studio, as well as other simulation results in the literature. It was also demonstrated that by using a continuous wave laser beam for heating the cathode, the emission pattern full width at half maximum (FWHM) of the transverse emission distribution is proportional to FWHM of the Gaussian profile for the laser beam. Additionally, by using the developed code, the effect of wall structure around the cathode on the back bombardment effect has been studied. According to the results, for a stable operation of the RF gun, one should consider the nose cone in vicinity of the cathode surface to reduce the back-bombardment effect. - Highlights: • We developed a 3D code to simulate the beam dynamics of thermionic RF gun. • Te impact of the emission pattern on the beam dynamic was investigated. • Different emission pattern results different emittance in the gun exit. • Using a nosecone around the cathode adjacent wall reduces back bombardment effect.

  4. Adaptive synthesis method for broadband array with frequency invariant beam pattern

    Institute of Scientific and Technical Information of China (English)

    ZHUWeijie; SUNJincai; ZENGXiangyang

    2003-01-01

    Based on adaptive technique, a design method for broadband array with frequency invariant beam pattern is presented. For a given beam pattern, the all design process can be completed automatically by computer without deriving expression of weight vector. The design process is divided into three steps: (1) Evaluate the weight vector in reference frequency by numerical method. (2) Obtain the weight vectors in other frequency by adaptive technique.(3) For the design target of frequency response given by weight vector at different frequency point, design FIR filter. The proposed method can be applied to arbitrary array and have no restriction on element patterns.

  5. Argon ion beam induced surface pattern formation on Si

    Energy Technology Data Exchange (ETDEWEB)

    Hofsäss, H.; Bobes, O.; Zhang, K. [2nd Institute of Physics, Faculty of Physics, University Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany)

    2016-01-21

    The development of self-organized surface patterns on Si due to noble gas ion irradiation has been studied extensively in the past. In particular, Ar ions are commonly used and the pattern formation was analyzed as function of ion incidence angle, ion fluence, and ion energies between 250 eV and 140 keV. Very few results exist for the energy regime between 1.5 keV and 10 keV and it appears that pattern formation is completely absent for these ion energies. In this work, we present experimental data on pattern formation for Ar ion irradiation between 1 keV and 10 keV and ion incidence angles between 50° and 75°. We confirm the absence of patterns at least for ion fluences up to 10{sup 18} ions/cm{sup 2}. Using the crater function formalism and Monte Carlo simulations, we calculate curvature coefficients of linear continuum models of pattern formation, taking into account contribution due to ion erosion and recoil redistribution. The calculations consider the recently introduced curvature dependence of the erosion crater function as well as the dynamic behavior of the thickness of the ion irradiated layer. Only when taking into account these additional contributions to the linear theory, our simulations clearly show that that pattern formation is strongly suppressed between about 1.5 keV and 10 keV, most pronounced at 3 keV. Furthermore, our simulations are now able to predict whether or not parallel oriented ripple patterns are formed, and in case of ripple formation the corresponding critical angles for the whole experimentally studied energies range between 250 eV and 140 keV.

  6. Trehalose glycopolymer resists allow direct writing of protein patterns by electron-beam lithography

    Science.gov (United States)

    Bat, Erhan; Lee, Juneyoung; Lau, Uland Y.; Maynard, Heather D.

    2015-03-01

    Direct-write patterning of multiple proteins on surfaces is of tremendous interest for a myriad of applications. Precise arrangement of different proteins at increasingly smaller dimensions is a fundamental challenge to apply the materials in tissue engineering, diagnostics, proteomics and biosensors. Herein, we present a new resist that protects proteins during electron-beam exposure and its application in direct-write patterning of multiple proteins. Polymers with pendant trehalose units are shown to effectively crosslink to surfaces as negative resists, while at the same time providing stabilization to proteins during the vacuum and electron-beam irradiation steps. In this manner, arbitrary patterns of several different classes of proteins such as enzymes, growth factors and immunoglobulins are realized. Utilizing the high-precision alignment capability of electron-beam lithography, surfaces with complex patterns of multiple proteins are successfully generated at the micrometre and nanometre scale without requiring cleanroom conditions.

  7. Enhanced Etching, Surface Damage Recovery, and Submicron Patterning of Hybrid Perovskites using a Chemically Gas-Assisted Focused-Ion Beam for Subwavelength Grating Photonic Applications.

    Science.gov (United States)

    Alias, Mohd S; Yang, Yang; Ng, Tien K; Dursun, Ibrahim; Shi, Dong; Saidaminov, Makhsud I; Priante, Davide; Bakr, Osman M; Ooi, Boon S

    2016-01-01

    The high optical gain and absorption of organic-inorganic hybrid perovskites have attracted attention for photonic device applications. However, owing to the sensitivity of organic moieties to solvents and temperature, device processing is challenging, particularly for patterning. Here, we report the direct patterning of perovskites using chemically gas-assisted focused-ion beam (GAFIB) etching with XeF2 and I2 precursors. We demonstrate etching enhancement in addition to controllability and marginal surface damage compared to focused-ion beam (FIB) etching without precursors. Utilizing the GAFIB etching, we fabricated a uniform and periodic submicron perovskite subwavelength grating (SWG) absorber with broadband absorption and nanoscale precision. Our results demonstrate the use of FIB as a submicron patterning tool and a means of providing surface treatment (after FIB patterning to minimize optical loss) for perovskite photonic nanostructures. The SWG absorber can be patterned on perovskite solar cells to enhance the device efficiency through increasing light trapping and absorption.

  8. Enhanced Etching, Surface Damage Recovery, and Submicron Patterning of Hybrid Perovskites using a Chemically Gas-Assisted Focused-Ion Beam for Subwavelength Grating Photonic Applications

    KAUST Repository

    Alias, Mohd Sharizal

    2015-12-22

    The high optical gain and absorption of organic–inorganic hybrid perovskites have attracted attention for photonic device applications. However, owing to the sensitivity of organic moieties to solvents and temperature, device processing is challenging, particularly for patterning. Here, we report the direct patterning of perovskites using chemically gas-assisted focused-ion beam (GAFIB) etching with XeF2 and I2 precursors. We demonstrate etching enhancement in addition to controllability and marginal surface damage compared to focused-ion beam (FIB) etching without precursors. Utilizing the GAFIB etching, we fabricated a uniform and periodic submicron perovskite subwavelength grating (SWG) absorber with broadband absorption and nanoscale precision. Our results demonstrate the use of FIB as a submicron patterning tool and a means of providing surface treatment (after FIB patterning to minimize optical loss) for perovskite photonic nanostructures. The SWG absorber can be patterned on perovskite solar cells to enhance the device efficiency through increasing light trapping and absorption.

  9. Reference Beam Pattern Design for Frequency Invariant Beamforming Based on Fast Fourier Transform.

    Science.gov (United States)

    Zhang, Wang; Su, Tao

    2016-09-22

    In the field of fast Fourier transform (FFT)-based frequency invariant beamforming (FIB), there is still an unsolved problem. That is the selection of the reference beam to make the designed wideband pattern frequency invariant (FI) over a given frequency range. This problem is studied in this paper. The research shows that for a given array, the selection of the reference beam pattern is determined by the number of sensors and the ratio of the highest frequency to the lowest frequency of the signal (RHL). The length of the weight vector corresponding to a given reference beam pattern depends on the reference frequency. In addition, the upper bound of the weight length to ensure the FI property over the whole frequency band of interest is also given. When the constraints are added to the reference beam, it does not affect the FI property of the designed wideband beam as long as the symmetry of the reference beam is ensured. Based on this conclusion, a scheme for reference beam design is proposed.

  10. Pattern transfer on large samples using a sub-aperture reactive ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Miessler, Andre; Mill, Agnes; Gerlach, Juergen W.; Arnold, Thomas [Leibniz-Institut fuer Oberflaechenmodifizierung (IOM), Permoserstrasse 15, D-04318 Leipzig (Germany)

    2011-07-01

    In comparison to sole Ar ion beam sputtering Reactive Ion Beam Etching (RIBE) reveals the main advantage of increasing the selectivity for different kind of materials due to chemical contributions during the material removal. Therefore RIBE is qualified to be an excellent candidate for pattern transfer applications. The goal of the present study is to apply a sub-aperture reactive ion beam for pattern transfer on large fused silica samples. Concerning this matter, the etching behavior in the ion beam periphery plays a decisive role. Using CF{sub 4} as reactive gas, XPS measurements of the modified surface exposes impurities like Ni, Fe and Cr, which belongs to chemically eroded material of the plasma pot as well as an accumulation of carbon (up to 40 atomic percent) in the beam periphery, respectively. The substitution of CF{sub 4} by NF{sub 3} as reactive gas reveals a lot of benefits: more stable ion beam conditions in combination with a reduction of the beam size down to a diameter of 5 mm and a reduced amount of the Ni, Fe and Cr contaminations. However, a layer formation of silicon nitride handicaps the chemical contribution of the etching process. These negative side effects influence the transfer of trench structures on quartz by changing the selectivity due to altered chemical reaction of the modified resist layer. Concerning this we investigate the pattern transfer on large fused silica plates using NF{sub 3}-sub-aperture RIBE.

  11. A COMPACTRIO-BASED BEAM LOSS MONITOR FOR THE SNS RF TEST CAVE

    Energy Technology Data Exchange (ETDEWEB)

    Blokland, Willem [ORNL; Armstrong, Gary A [ORNL

    2009-01-01

    An RF Test Cave has been built at the Spallation Neutron Source (SNS) to be able to test RF cavities without interfering the SNS accelerator operations. In addition to using thick concrete wall to minimize radiation exposure, a Beam Loss Monitor (BLM) must abort the operation within 100 usec when the integrated radiation within the cave exceeds a threshold. We choose the CompactRIO platform to implement the BLM based on its performance, cost-effectiveness, and rapid development. Each in/output module is connected through an FPGA to provide point-by-point processing. Every 10 usec the data is acquired analyzed and compared to the threshold. Data from the FPGA is transferred using DMA to the real-time controller, which communicates to a gateway PC to talk to the SNS control system. The system includes diagnostics to test the hardware and integrates the losses in real-time. In this paper we describe our design, implementation, and results

  12. Real-Time System Supervision for the LHC Beam Loss Monitoring System at CERN

    CERN Document Server

    Zamantzas, C; Effinger, E; Emery, J; Jackson, S

    2014-01-01

    The strategy for machine protection and quench prevention of the Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) is mainly based on the Beam Loss Monitoring (BLM) system. The LHC BLM system is one of the most complex and large instrumentation systems deployed in the LHC. In addition to protecting the collider, the system also needs to provide a means of diagnosing machine faults and deliver feedback of the losses to the control room as well as to several systems for their setup and analysis. In order to augment the dependability of the system several layers of supervision has been implemented internally and externally to the system. This paper describes the different methods employed to achieve the expected availability and system fault detection.

  13. Pattern transfer on fused silica samples using sub-aperture reactive ion beam etching

    Energy Technology Data Exchange (ETDEWEB)

    Miessler, Andre; Arnold, Thomas [Leibniz-Institut fuer Oberflaechenmodifizierung (IOM), Permoserstrasse 15, D-04318 Leipzig (Germany)

    2012-07-01

    In comparison to sole Ar ion beam sputtering Reactive Ion Beam Etching (RIBE) reveals the main advantage of increasing the selectivity for different kind of materials due to chemical contributions during the material removal. Therefore RIBE is qualified to be an excellent candidate for pattern transfer applications. The goal of the present study is to apply a sub-aperture reactive ion beam for pattern transfer on large fused silica samples. Concerning this matter, the etching behavior in the ion beam periphery plays a decisive role. Using a Kaufman-typed ion source with NF{sub 3} as reactive gas, XPS measurements of the modified surface exposes impurities like Ni, Fe and Cr, which belongs to chemically eroded material of the plasma pot and a layer formation of silicon nitride, handicaps the etching process mainly in the beam periphery where the sputtering contribution decrease. These side effects influence the pattern transfer of trench structures, produced in AZ MIR 701 photoresist by lithography on a 2'' fused silica plate, by changing the selectivity due to modified chemical reactions of the resist layer. Concerning this we investigate a RF-Ion source for sub aperture reactive ion beam applications and finally we examine the pattern transfer on large fused silica plates using NF{sub 3}-sub-aperture RIBE.

  14. Updated analytical solutions of continuity equation for electron beams precipitation - II. Mixed energy losses

    Science.gov (United States)

    Zharkova, V. V.; Dobranskis, R. R.

    2016-06-01

    In this paper we consider simultaneous analytical solutions of continuity equations for electron beam precipitation (a) in collisional losses and (b) in ohmic losses, or mixed energy losses (MEL) by applying the iterative method to calculate the resulting differential densities at given precipitation depth. The differential densities of precipitating electrons derived from the analytical solutions for MELs reveal increased flattening at energies below 10-30 keV compared to a pure collisional case. This flattening becomes stronger with an increasing precipitation depth turning into a positive slope at greater precipitation depths in the chromosphere resulting in a differential density distribution with maximum that shifts towards higher energies with increase in column depth, while the differential densities combining precipitating and returning electrons are higher at lower energies than those for a pure collisional case. The resulting hard X-ray (HXR) emission produced by the beams with different initial energy fluxes and spectral indices is calculated using the MEL approach for different ratios between the differential densities of precipitating and returning electrons. The number of returning electrons can be even further enhanced by a magnetic mirroring, not considered in the present model, while dominating at lower atmospheric depths where the magnetic convergence and magnitude are the highest. The proposed MEL approach provides an opportunity to account simultaneously for both collisional and ohmic losses in flaring events, which can be used for a quick spectral fitting of HXR spectra and evaluation of a fraction of returning electrons versus precipitating ones. The semi-analytical MEL approach is used for spectral fitting to Reuven High Energy Solar Spectroscopic Imager observations of nine C, M and X class flares revealing a close fit to the observations and good resemblance to numerical FP solutions.

  15. Characteristics of submicron patterns fabricated by gallium focused-ion-beam sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Morimoto, H.; Sasaki, Y.; Watakabe, Y.; Kato, T.

    1985-01-01

    Cross sections of the patterns fabricated in (100) GaAs by 100-keV gallium focused ion beam have been studied using a scanning electron microscope (SEM). The probe size of the ion beam is 0.1--0.15 ..mu..m at the current of 100 pA. The etched depth becomes saturated at the high dose region (about 5.0 x 10/sup -6/ C/cm) because of the redeposition effect. The pattern profile becomes asymmetric if it is made up of several adjacent lines perpendicular to the beam scanning direction due to the redeposition effect and the increase of sputtering yield for each scan, which is caused by the change of ion beam incident angle. These effects can be eliminated by the use of multiwriting method.

  16. Beam Patterns of the Five hundred metre Aperture Spherical Telescope: Optimization

    CERN Document Server

    Dong, B

    2013-01-01

    The Five hundred meter Aperture Spherical Telescope (FAST) uses adaptive spherical panels to realize the huge collecting area for radio waves. In this paper, we try to explore the optimal parameters for the curvature radius of spherical panels and the focal distance by comparison of the calculated beam patterns. We show that to get the best beam shape and maximum gain, the optimal curvature radius of panels is around 300m, and a small shift of focal distance of a few cm is needed. The aperture efficiency can be improved by ~10 at 3GHz by this small shift. We also try to optimize the panel positioning for the best beam, and find that panel shifts of a few mm can improve the beam pattern by a similar extent. Our results indicate that the accurate control of the feed and panel position to the mm level is very crucial to the stability of FAST performance.

  17. CO2 lasers: beam patterns in relation to surgical use.

    Science.gov (United States)

    Fava, G; Emanuelli, H; Cascinelli, N; Bandieramonte, G; Canestri, F; Marchesini, R

    1983-01-01

    According to surgeons operating with a variety of CO2 lasers available at the National Cancer Institute of Milan (Coherent, Sharplan, Valfivre), these lasers have different cutting and coagulation properties. To identify what physical parameters might corroborate the subjective impression of the surgeons, a comparative study of the crater forms in perspex samples was performed. Perspex was chosen for its thermal properties (in fact, its thermal conductivity and diffusivity are similar to those of organic tissue) and because it allowed good visualization and measurement of crater characteristics. Depth of penetration, crater diameter, and extension of thermal damage were measured against power, focal length, and exposure time for each CO2 laser model. These results can be used as an index of behaviour of different surgical lasers. It appears that for fully characterizing the interaction of surgical lasers with the sample, it is necessary to specify either power, focal length, exposure time, or beam mode.

  18. The effect of residual gas scattering on Ga ion beam patterning of graphene

    Energy Technology Data Exchange (ETDEWEB)

    Thissen, Nick F. W., E-mail: n.f.w.thissen@tue.nl, E-mail: a.a.bol@tue.nl; Vervuurt, R. H. J.; Weber, J. W.; Kessels, W. M. M.; Bol, A. A., E-mail: n.f.w.thissen@tue.nl, E-mail: a.a.bol@tue.nl [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Mulders, J. J. L. [FEI Electron Optics, Achtseweg Noord 5, 5600 KA Eindhoven (Netherlands)

    2015-11-23

    The patterning of graphene by a 30 kV Ga{sup +} focused ion beam (FIB) is studied by in-situ and ex-situ Raman spectroscopy. It is found that the graphene surrounding the patterned target area can be damaged at remarkably large distances of more than 10 μm. We show that scattering of the Ga ions in the residual gas of the vacuum system is the main cause of the large range of lateral damage, as the size and shape of the tail of the ion beam were strongly dependent on the system background pressure. The range of the damage was therefore greatly reduced by working at low pressures and limiting the total amount of ions used. This makes FIB patterning a feasible alternative to electron beam lithography as long as residual gas scattering is taken into account.

  19. Characteristics of Patients with Hearing Aids according to the Degree and Pattern of Hearing Loss

    Science.gov (United States)

    Byun, Young Seok; Kim, Sung Su; Park, Sang Hyun; Park, Eun Bin; Kim, Ho Joong; Kim, Sang Hoon

    2016-01-01

    Background and Objectives This study was designed to assess the characteristics of patients according to the degree and audiogram shape of hearing loss and the association of these characteristics with hearing aids (HA) choice, return rate, and cause of return. Subjects and Methods This study included 460 individuals who received HAs from 2011 to 2015. The relationships between type of HA and age, primary and accompanying symptoms, HA choice and return and cause of return were evaluated according to the degree and pattern of hearing loss. Results HA type did not differ significantly according to the degree and pattern of hearing loss. Intensity of hearing loss was greater in male than in female (phearing loss intensified, behind-the-ear and in-the-ear types increased and Open type decreased (phearing loss. The main causes of HA return were costs, psychological fears and adaptive failure. Conclusions Choice of HA is affected by age, sex, and degree and pattern of hearing loss. HA for hearing rehabilitation in patients with hearing loss can be personalized according to each patient's characteristics and tendencies. PMID:27942600

  20. Spatial Patterns of Forest Cover Loss in the Democratic Republic of Congo

    Science.gov (United States)

    Molinario, G.; Hansen, M.; Potapov, P.; Justice, C. O.

    2013-12-01

    Three groups of metrics of spatial patterns of forest cover loss were calculated for the Democratic Republic of Congo (DRC). While other studies had previously assessed landscape patterns in the Congo Basin, they had done so for small areas due to data limitations. The input data for this study, the Forets d;Afrique Central Evaluee par Teledetection(FACET), allowed the analysis to be performed at the national level. FACET is a landsat-scale dataset giving an unprecedented synoptic view of forest cover and forest cover loss for the DRC for three time periods: 2000, 2005 and 2010. The three groups of metrics evaluated the following spatial characteristics of forest cover loss for the same standard 1.5km unit of area: proportions of typologies of forest lost, forest fragmentation and proximity of forest loss patches from other land cover types. Results indicate that there are several different typologies of forest cover loss in the DRC, and offer quantitative explanations of these differences, providing a valuable locally-relevant tool for land use planning, available at the national level. Spatial patterns of forest cover loss highlight differences between areas of high primary forest loss due to agriculture conversion in frontier deforestation, such as in the east of the country, areas of equivalent primary and secondary forest loss emanating from the rural complex and areas of variable proportions of primary and secondary forest loss but important ecological repercussions of forest fragmentation due to isolated, but systematic forest perforations. Typologies of spatial patterns of forest cover loss are presented as well as their correlated drivers, and ecological, conservation and land use planning considerations are discussed.

  1. A micro-pattern gaseous detector for beam monitoring in ion-therapy

    Energy Technology Data Exchange (ETDEWEB)

    Terakawa, A.; Ishii, K.; Matsuyama, S.; Kikuchi, Y.; Togashi, T.; Arikawa, J.; Yamashita, W.; Takahashi, Y.; Fujishiro, F. [Department of Quantum Science and Energy Engineering, Tohoku University (Japan); Yamazaki, H.; Sakemi, Y. [Cyclotron and Radioisotope Center, Tohoku University (Japan)

    2015-12-15

    A micro-pattern gaseous detector based on gas electron multiplier technology (GEM detector) was developed as a new transmission beam monitor for charged-particle therapy to obtain real-time information about the parameters of a therapeutic beam. Feasibility tests for the GEM detector were performed using an 80-MeV proton beam to evaluate the lateral intensity distributions of a pencil beam and the dose delivered to a target. The beam intensity distributions measured with the GEM detector were in good agreement with those measured with an imaging plate while the charge output from the GEM detector was in proportion to that of a reference dose monitor of an ionization chamber design. These experimental results showed that the GEM detector can be used not only as a beam monitor for the position and two-dimensional intensity distribution but also as a dose monitor. Thus, it is possible to simultaneously measure these beam parameters for beam control in charged-particle therapy using a single GEM-based transmission monitor.

  2. Codesign of Beam Pattern and Sparse Frequency Waveforms for MIMO Radar

    Directory of Open Access Journals (Sweden)

    Chaoyun Mai

    2015-01-01

    Full Text Available Multiple-input multiple-output (MIMO radar takes the advantages of high degrees of freedom for beam pattern design and waveform optimization, because each antenna in centralized MIMO radar system can transmit different signal waveforms. When continuous band is divided into several pieces, sparse frequency radar waveforms play an important role due to the special pattern of the sparse spectrum. In this paper, we start from the covariance matrix of the transmitted waveform and extend the concept of sparse frequency design to the study of MIMO radar beam pattern. With this idea in mind, we first solve the problem of semidefinite constraint by optimization tools and get the desired covariance matrix of the ideal beam pattern. Then, we use the acquired covariance matrix and generalize the objective function by adding the constraint of both constant modulus of the signals and corresponding spectrum. Finally, we solve the objective function by the cyclic algorithm and obtain the sparse frequency MIMO radar waveforms with desired beam pattern. The simulation results verify the effectiveness of this method.

  3. Progress toward a general grating patterning technology using phase-locked scanning beams

    Science.gov (United States)

    Schattenburg, Mark L.; Chen, Carl G.; Heilmann, Ralf K.; Konkola, Paul T.; Pati, G. S.

    2002-01-01

    The fabrication of large high-quality diffraction gratings remains one of the most challenging tasks in optical fabrication. Traditional direct-write methods, such as diamond ruling or electron-beam lithography, can be extremely slow and result in gratings with undesired phase errors. Holographic methods, while generally resulting in gratings with smoother phase, frequently require large aspheres and lengthy optical setup in order to achieve desired period chirps. In this paper we describe a novel interference lithography method called scanning-beam interference lithography (SBIL) that utilizes small phase-locked scanning beams to write general periodic patterns onto large substrates. Small mutually coherent beams are phase controlled by high-bandwidth electro-optic components and caused to overlap and interfere, generating a small grating image. The image is raster-scanned over the substrate by use of a high-precision interferometer-controlled air bearing stage, resulting in large grating patterns. We will describe a prototype system in our laboratory designed to write gratings with extremely low phase distortion. The system is being generalized to pattern gratings with arbitrary period progressions (chirps). This technology, with extensions, will allow the rapid, low cost patterning of high-fidelity periodic patterns of arbitrary geometry on large substrates that could be of great interest to astronomers.

  4. Fast detection of manufacturing systematic design pattern failures causing device yield loss

    Science.gov (United States)

    Le Denmat, Jean-Christophe; Feldman, Nelly; Riewer, Olivia; Yesilada, Emek; Vallet, Michel; Suzor, Christophe; Talluto, Salvatore

    2015-03-01

    Starting from the 45nm technology node, systematic defectivity has a significant impact on device yield loss with each new technology node. The effort required to achieve patterning maturity with zero yield detractor is also significantly increasing with technology nodes. Within the manufacturing environment, new in-line wafer inspection methods have been developed to identify device systematic defects, including the process window qualification (PWQ) methodology used to characterize process robustness. Although patterning is characterized with PWQ methodology, some questions remain: How can we demonstrate that the measured process window is large enough to avoid design-based defects which will impact the device yield? Can we monitor the systematic yield loss on nominal wafers? From device test engineering point of view, systematic yield detractors are expected to be identified by Automated Test Pattern Generator (ATPG) test results diagnostics performed after electrical wafer sort (EWS). Test diagnostics can identify failed nets or cells causing systematic yield loss [1],[2]. Convergence from device failed nets and cells to failed manufacturing design pattern are usually based on assumptions that should be confirmed by an electrical failure analysis (EFA). However, many EFA investigations are required before the design pattern failures are found, and thus design pattern failure identification was costly in time and resources. With this situation, an opportunity to share knowledge exists between device test engineering and manufacturing environments to help with device yield improvement. This paper presents a new yield diagnostics flow dedicated to correlation of critical design patterns detected within manufacturing environment, with the observed device yield loss. The results obtained with this new flow on a 28nm technology device are described, with the defects of interest and the device yield impact for each design pattern. The EFA done to validate the design

  5. Patterns of functional vision loss in glaucoma determined with archetypal analysis.

    Science.gov (United States)

    Elze, Tobias; Pasquale, Louis R; Shen, Lucy Q; Chen, Teresa C; Wiggs, Janey L; Bex, Peter J

    2015-02-06

    Glaucoma is an optic neuropathy accompanied by vision loss which can be mapped by visual field (VF) testing revealing characteristic patterns related to the retinal nerve fibre layer anatomy. While detailed knowledge about these patterns is important to understand the anatomic and genetic aspects of glaucoma, current classification schemes are typically predominantly derived qualitatively. Here, we classify glaucomatous vision loss quantitatively by statistically learning prototypical patterns on the convex hull of the data space. In contrast to component-based approaches, this method emphasizes distinct aspects of the data and provides patterns that are easier to interpret for clinicians. Based on 13 231 reliable Humphrey VFs from a large clinical glaucoma practice, we identify an optimal solution with 17 glaucomatous vision loss prototypes which fit well with previously described qualitative patterns from a large clinical study. We illustrate relations of our patterns to retinal structure by a previously developed mathematical model. In contrast to the qualitative clinical approaches, our results can serve as a framework to quantify the various subtypes of glaucomatous visual field loss.

  6. Development of a Beam Loss Measurement System with Gigabit Ethernet Readout at CERN

    CERN Document Server

    Kwiatkowski, M; Angelogiannopoulos, E; Dehning, B; Jackson, S; Vigano, W; Zamantzas, C

    2012-01-01

    The aim of the BLM Dual Polarity module under development at the European Organisation for Nuclear Research (CERN) is to measure and digitise with high precision the current produced by several types of beam loss detectors. In its default configuration, it is expected to provide data to the processing electronics through two point-to-point connections with bidirectional multi-gigabit optical links. For the development phases as well as later serving as a standalone measurement system, its reconfigurable FPGA device is exploited to provide a soft-core CPU with a custom made server. This server, running on the CPU, will expose through the Gigabit Ethernet connection and the TCP/IP protocol different types of data in the network. In this paper the development of the system and of the communication protocol is explored as well as the accompanying client ap- plication that is realised with the purpose of commanding, collecting storing and viewing the different types of data.

  7. 10 Orders of Magnitude Current Measurement Digitisers for the CERN Beam Loss Systems

    CERN Document Server

    Vigano, W; Dehning, B; Kwiatkowski, M; Venturini, G G; Zamantzas, C

    2014-01-01

    A wide range current digitizer card is needed for the acquisition module of the beam loss monitoring systems in the CERN Injector Complex. The fully differential frequency converter allows measuring positive and negative input currents with a resolution of 31nA in an integration window of 2μs. Increasing the integration window, the dynamic range covers 2•1010 were the upper part of the range is converted by measuring directly the voltage drop on a resistor. The key elements of this design are the fully differential integrator and the switches operated by an FPGA. The circuit is designed to avoid any dead time in the acquisition and reliability and failsafe operational considerations are main design goals. The circuit will be discussed in detail and lab and field measurements will be shown.

  8. Improved design and construction of an ionization chamber for the CSNS beam loss monitor (BLM)

    Institute of Scientific and Technical Information of China (English)

    TIAN Jian-Min; XU Mei-Hang; ZHAO Zhong-Liang; CHEN Chang; RUAN Xiang-Dong; CHEN Yuan-Bo; XU Tao-Guang; LU Shuang-Tong

    2012-01-01

    Based on the first ionization chamber (IC) prototype,the structure,working gas component and electrode material of the IC are improved.The test of the improved IC shows that the plateau length is about 2000 V,the plateau slope is less than 0.2%/100 V,the sensitivity is 19.6 pA/rad.h-1,the up-limitation of the linearity can be up to 3.6× 105 rad/h,and the applied voltage can be operated to 3500 V.The test results show that the performance of the improved IC meets the requirements of the beam loss monitor.

  9. Effects of Optical Loss Factors on Heliostat Field Layout for Beam-Down Solar Concentrating Systems

    Science.gov (United States)

    Utamura, Motoaki; Takamatsu, Tadahiko; Yuasa, Minoru; Kajita, Rina; Yamamoto, Takashi

    A methodology to give an optimal layout of a group of heliostats has been developed for beam-down concentrating solar tower systems. Given the maximum solar power together with optical parameters, the method determines an optimal configuration of a heliostat field around a tower. Various optical losses such as cosine factor, shadowing and blocking at heliostats are considered in the calculation. Furthermore, spillage at the receiver is taken into account due to the spread of light caused by the effects of a finite solar disk, flat facet and various stochastic errors in optical hardware and control. It is found the effect of spillage becomes significant at heliostats from the tower at the distance farther than four times of upper focus height of the reflector when receiver diameter is one fifteenth of the height and dominates the configuration of the optimal heliostat layout.

  10. 10 orders of magnitude current measurement digitisers for the CERN beam loss systems

    Science.gov (United States)

    Viganò, W.; Alsdorf, M.; Dehning, B.; Kwiatkowski, M.; Venturini, G. G.; Zamantzas, C.

    2014-02-01

    A wide range current digitizer card is needed for the acquisition module of the beam loss monitoring systems in the CERN Injector Complex. The fully differential frequency converter allows measuring positive and negative input currents with a resolution of 31 nA in an integration window of 2 μs. Increasing the integration window, the dynamic range covers 21010 were the upper part of the range is converted by measuring directly the voltage drop on a resistor. The key elements of this design are the fully differential integrator and the switches operated by an FPGA. The circuit is designed to avoid any dead time in the acquisition and reliability and failsafe operational considerations are main design goals. The circuit will be discussed in detail and lab and field measurements will be shown.

  11. Study on the radiation problem caused by electron beam loss in accelerator tubes

    Institute of Scientific and Technical Information of China (English)

    LI Quan-Feng; GUO Bing-Qi; ZHANG Jie-Xi; CHEN Huai-Bi

    2008-01-01

    The beam dynamic code PARMELA was used to simulate the transportation process of accelerating electrons in S-band SW linacs with different energies of 2.5, 6 and 20 MeV. The results indicated that in the ideal condition, the percentage of electron beam loss was 50% in accelerator tubes. Also we calculated the spectrum, the location and angular distribution of the lost electrons. Calculation performed by Monte Carlo code MCNP demonstrated that the radiation distribution of lost electrons was nearly uniform along the tube axis, the angular distributions of the radiation dose rates of the three tubes were similar, and the highest leaking dose was at the angle of 160° with respect to the axis. The lower the energy of the accelerator, the higher the radiation relative leakage. For the 2.5 MeV accelerator, the maximum dose rate reached 5% of the main dose and the one on the head of the electron gun was 1%, both of which did not meet the eligible protection requirement for accelerators. We adopted different shielding designs for different accelerators. The simulated result showed that the shielded radiation leaking dose rates fulfilled the requirement.

  12. Fast Computation of Wideband Beam Pattern for Designing Large-Scale 2-D Arrays.

    Science.gov (United States)

    Chi, Cheng; Li, Zhaohui

    2016-06-01

    For real-time and high-resolution 3-D ultrasound imaging, the design of sparse distribution and weights of elements of a large-scale wideband 2-D array is needed to reduce hardware cost and achieve better directivity. However, due to the high time consumption of computing the wideband beam pattern, the design methods that need massive iterations have rarely been applied to design large-scale wideband 2-D arrays by directly computing the wideband beam pattern. In this paper, a fast method is proposed to realize the computation of a wideband beam pattern of arbitrary 2-D arrays in the far field in order to design large-scale wideband 2-D arrays. The proposed fast method exploits two important techniques: 1) nonuniform fast Fourier transform (FFT) and 2) short inverse FFT. Compared with the commonly used ultrasound simulator Field II, two orders of magnitude improvement in computation speed is achieved with comparable accuracy. The proposed fast method enables massive iterations of direct wideband beam pattern computation of arbitrary large-scale 2-D arrays. A design example in this paper demonstrates that the proposed fast method can help achieve better performance in designing large-scale wideband 2-D arrays.

  13. Electrical and shading power losses of decorative PV front contact patterns

    Energy Technology Data Exchange (ETDEWEB)

    Radike, Michael; Summhammer, Johann [Austrian Univ., Atomic Inst., Vienna (Austria)

    1999-07-01

    Visual appeal is an important criterion for the acceptance of photovoltaic modules in facades and roofs of buildings, or in village electrification. With crystalline silicon solar cells, the busbars are often seen as disturbing. Therefore, we tried to convert the busbars into an attractive feature by incorporation artistic design. Busbars should have an eye-catching effect. But increase shading or non-optimal finger layout should have no significant effect on efficiency. In the present work we calculated the different losses of newly designed front contact patterns. The design concept was to have a few basic front metallisation grids at the cell level, which would permit a large number of different appearances at the module level. Fifteen new metallization patterns were compared to the standard metallization grid regarding the differences in shading and in the electrical losses. Nine of the new patterns are variations of the well known two-busbars scheme. Two patterns have connection points in the middle of each side of the square cell and a completely asymmetric inner layout. This leads to a large number of possibilities of irregular looking modules, not unlike stone or broken glass. Another one is designed to create the appearance of a hexagon web at the module level. Three other cells are designed to create an 'art-deco' pattern when combined to a module. By taking into account resistive losses in the emitter layer, in the fingers and in the busbars, and contact losses between fingers and emitter layer, as well as shading losses, we find that the efficiency of a cell with the worst patterns would be only 0.71% absolute below that of a cell with standard pattern and an efficiency of 13.80% at 1-sun conditions (1000 W/m{sup 2}). Artistic design of the busbar layout of crystalline silicon solar cells can therefore be achieved without an undue decrease of conversion. (Author)

  14. Energy loss of a fast-electron beam due to the excitation of collective oscillation in hot plasma

    Institute of Scientific and Technical Information of China (English)

    Ma Jin-Yi; Qiu Xi-Jun; Zhu Zhi-Yuan

    2004-01-01

    Energy loss due to a fast-electron beam interacting with the hot plasma at a high density is analysed theoretically.By splitting the particle density fluctuations into the individual part due to the random thermal motion of the individual electrons and the collective part due to plasma-wave excitation, we are concerned with the collective interaction of the relativistic plasma electrons resulting from the Coulomb interactions. Consequently, we derive the frequency of the hot plasma and the "Debye length" with the modification of the relativistic effect. And finally we calculate the energy loss of a fast-electron beam due to the excitation of collective oscillation in the hot plasma.

  15. Habitat loss, not fragmentation, drives occurrence patterns of Canada lynx at the southern range periphery.

    Directory of Open Access Journals (Sweden)

    Megan L Hornseth

    Full Text Available Peripheral populations often experience more extreme environmental conditions than those in the centre of a species' range. Such extreme conditions include habitat loss, defined as a reduction in the amount of suitable habitat, as well as habitat fragmentation, which involves the breaking apart of habitat independent of habitat loss. The 'threshold hypothesis' predicts that organisms will be more affected by habitat fragmentation when the amount of habitat on the landscape is scarce (i.e., less than 30% than when habitat is abundant, implying that habitat fragmentation may compound habitat loss through changes in patch size and configuration. Alternatively, the 'flexibility hypothesis' predicts that individuals may respond to increased habitat disturbance by altering their selection patterns and thereby reducing sensitivity to habitat loss and fragmentation. While the range of Canada lynx (Lynx canadensis has contracted during recent decades, the relative importance of habitat loss and habitat fragmentation on this phenomenon is poorly understood. We used a habitat suitability model for lynx to identify suitable land cover in Ontario, and contrasted occupancy patterns across landscapes differing in cover, to test the 'threshold hypothesis' and 'flexibility hypothesis'. When suitable land cover was widely available, lynx avoided areas with less than 30% habitat and were unaffected by habitat fragmentation. However, on landscapes with minimal suitable land cover, lynx occurrence was not related to either habitat loss or habitat fragmentation, indicating support for the 'flexibility hypothesis'. We conclude that lynx are broadly affected by habitat loss, and not specifically by habitat fragmentation, although occurrence patterns are flexible and dependent on landscape condition. We suggest that lynx may alter their habitat selection patterns depending on local conditions, thereby reducing their sensitivity to anthropogenically-driven habitat

  16. Habitat Loss, Not Fragmentation, Drives Occurrence Patterns of Canada Lynx at the Southern Range Periphery

    Science.gov (United States)

    Hornseth, Megan L.; Walpole, Aaron A.; Walton, Lyle R.; Bowman, Jeff; Ray, Justina C.; Fortin, Marie-Josée; Murray, Dennis L.

    2014-01-01

    Peripheral populations often experience more extreme environmental conditions than those in the centre of a species' range. Such extreme conditions include habitat loss, defined as a reduction in the amount of suitable habitat, as well as habitat fragmentation, which involves the breaking apart of habitat independent of habitat loss. The ‘threshold hypothesis’ predicts that organisms will be more affected by habitat fragmentation when the amount of habitat on the landscape is scarce (i.e., less than 30%) than when habitat is abundant, implying that habitat fragmentation may compound habitat loss through changes in patch size and configuration. Alternatively, the ‘flexibility hypothesis’ predicts that individuals may respond to increased habitat disturbance by altering their selection patterns and thereby reducing sensitivity to habitat loss and fragmentation. While the range of Canada lynx (Lynx canadensis) has contracted during recent decades, the relative importance of habitat loss and habitat fragmentation on this phenomenon is poorly understood. We used a habitat suitability model for lynx to identify suitable land cover in Ontario, and contrasted occupancy patterns across landscapes differing in cover, to test the ‘threshold hypothesis’ and ‘flexibility hypothesis’. When suitable land cover was widely available, lynx avoided areas with less than 30% habitat and were unaffected by habitat fragmentation. However, on landscapes with minimal suitable land cover, lynx occurrence was not related to either habitat loss or habitat fragmentation, indicating support for the ‘flexibility hypothesis’. We conclude that lynx are broadly affected by habitat loss, and not specifically by habitat fragmentation, although occurrence patterns are flexible and dependent on landscape condition. We suggest that lynx may alter their habitat selection patterns depending on local conditions, thereby reducing their sensitivity to anthropogenically-driven habitat

  17. Synthesis of Steered Flat-top Beam Pattern Using Evolutionary Algorithm

    Directory of Open Access Journals (Sweden)

    D. Mandal

    2016-12-01

    Full Text Available In this paper a pattern synthesis method based on Evolutionary Algorithm is presented. A Flat-top beam pattern has been generated from a concentric ring array of isotropic elements by finding out the optimum set of elements amplitudes and phases using Differential Evolution algorithm. The said pattern is generated in three predefined azimuth planes instate of a single phi plane and also verified for a range of azimuth plane for the same optimum excitations. The main beam is steered to an elevation angle of 30 degree with lower peak SLL and ripple. Dynamic range ratio (DRR is also being improved by eliminating the weakly excited array elements, which simplify the design complexity of feed networks.

  18. Localized conductive patterning via focused electron beam reduction of graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Songkil; Henry, Mathias [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Kulkarni, Dhaval D.; Zackowski, Paul; Jang, Seung Soon; Tsukruk, Vladimir V. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Fedorov, Andrei G., E-mail: agf@gatech.edu [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2015-03-30

    We report on a method for “direct-write” conductive patterning via reduction of graphene oxide (GO) sheets using focused electron beam induced deposition (FEBID) of carbon. FEBID treatment of the intrinsically dielectric graphene oxide between two metal terminals opens up the conduction channel, thus enabling a unique capability for nanoscale conductive domain patterning in GO. An increase in FEBID electron dose results in a significant increase of the domain electrical conductivity with improving linearity of drain-source current vs. voltage dependence, indicative of a change of graphene oxide electronic properties from insulating to semiconducting. Density functional theory calculations suggest a possible mechanism underlying this experimentally observed phenomenon, as localized reduction of graphene oxide layers via interactions with highly reactive intermediates of electron-beam-assisted dissociation of surface-adsorbed hydrocarbon molecules. These findings establish an unusual route for using FEBID as nanoscale lithography and patterning technique for engineering carbon-based nanomaterials and devices with locally tailored electronic properties.

  19. Influence of phase separation for surfactant driven pattern formation during ion beam erosion

    Energy Technology Data Exchange (ETDEWEB)

    Hofsaess, Hans; Zhang, Kun; Vetter, Ulrich; Bobes, Omar; Pape, Andre; Gehrke, Hans-Gregor; Broetzmann, Marc [II. Physikalisches Institut, Goettingen Univ. (Germany)

    2012-07-01

    We will present results on metal surfactant driven self-organized pattern formation on surfaces by ion beam erosion, with a focus on the role of phase separation for the initial steps of pattern formation. Si substrates were irradiated with 5 keV Xe ions at normal incidence and ion fluences up to 5.10{sup 17} Xe/cm{sup 2} under continuous deposition of surfactant atoms. In the absence of such surfactants uniform flat surfaces are obtained, while in the presence of Fe and Mo surfactants pronounced patterns like dots, combinations of dots and ripples with wavelengths around 100 nm are generated. The surfactant coverage and deposition direction determine the pattern type and the pattern orientation, respectively. A critical steady-state coverage for onset of dot formation and onset of ripple formation is in the range of 10{sup 15} and 5.10{sup 15} Xe/cm{sup 2}. The steady-state surface region consists of a thin amorphous metal silicide layer with high metal concentration in the ripple and dot regions. Pattern formation is explained by ion induced diffusion and phase separation of the initially flat amorphous silicide layer and subsequent ion beam erosion with composition dependent sputter yield. To investigate the role of initial phase separation we additionally compare the pattern formation for different other metal surfactants.

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

    Science.gov (United States)

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

    2013-08-01

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

  1. A Cherenkov-based Beam Loss Scintillator system for beam, background and online luminosity monitoring at the LHCb experiment at CERN

    CERN Document Server

    Alessio, F; Jacobsson, R

    2013-01-01

    The installation of a scintillator-based system in the LHCb cavern was initially proposed in order to observe injection problems around the LHCb interaction region. Thanks to the fact that LHCb had already developed a custom-made electronics board (BPIM) for the LHCb beam pickups and global LHCb timing monitoring, a complete, inexpensive but flexible and robust system was quickly developed and installed few cm from the beam pipe just in front of the LHCb VELO detector in time for the very first beams injected in the LHC. The current and final system – commonly referred to as Beam Loss Scintillator (BLS) system - ultimately played a central role in the fast beam, background and online luminosity monitoring at LHCb. In this paper, the features of the detector – based on quartz radiator and Cherenkov light - are described, including the functionalities that the system acquired during the proton-proton physics programmes in 2009- 2013 thanks to its flexibility, reliability and sensitivity to beam hal...

  2. Focused-ion beam patterning of organolead trihalide perovskite for subwavelength grating nanophotonic applications

    KAUST Repository

    Alias, Mohd Sharizal

    2015-07-30

    The coherent amplified spontaneous emission and high photoluminescence quantum efficiency of organolead trihalide perovskite have led to research interest in this material for use in photonic devices. In this paper, the authors present a focused-ion beam patterning strategy for methylammonium lead tribromide (MAPbBr3) perovskite crystal for subwavelength grating nanophotonic applications. The essential parameters for milling, such as the number of scan passes, dwell time, ion dose, ion current, ion incident angle, and gas-assisted etching, were experimentally evaluated to determine the sputtering yield of the perovskite. Based on our patterning conditions, the authors observed that the sputtering yield ranged from 0.0302 to 0.0719 μm3/pC for the MAPbBr3 perovskite crystal. Using XeF2 for the focused-ion beam gas-assisted etching, the authors determined that the etching rate was reduced to between 0.40 and 0.97, depending on the ion dose, compared with milling with ions only. Using the optimized patterning parameters, the authors patterned binary and circular subwavelength grating reflectors on the MAPbBr3 perovskite crystal using the focused-ion beam technique. Based on the computed grating structure with around 97% reflectivity, all of the grating dimensions (period, duty cycle, and grating thickness) were patterned with nanoscale precision (>±3 nm), high contrast, and excellent uniformity. Our results provide a platform for utilizing the focused-ion beam technique for fast prototyping of photonic nanostructures or nanodevices on organolead trihalide perovskite.

  3. Severe signal loss in diamond beam loss monitors in high particle rate environments by charge trapping in radiation-induced defects

    CERN Document Server

    Kassel, Florian; Dabrowski, Anne; de Boer, Wim

    2016-01-01

    The beam condition monitoring leakage (BCML) system is a beam monitoring device in the compact muon solenoid (CMS) experiment at the large hadron collider (LHC). As detectors 32 poly-crystalline (pCVD) diamond sensors are positioned in rings around the beam pipe. Here, high particle rates occur from the colliding beams scattering particles outside the beam pipe. These particles cause defects, which act as traps for the ionization, thus reducing the charge collection efficiency (CCE). However, the loss in CCE was much more severe than expected from low rate laboratory measurements and simulations, especially in single-crystalline (sCVD) diamonds, which have a low initial concentration of defects. The reason why in real experiments the CCE is much worse than in laboratory experiments is related to the ionization rate. At high particle rates the trapping rate of the ionization is so high compared with the detrapping rate, that space charge builds up. This space charge reduces locally the internal electric field,...

  4. Orbital angular moment of a partially coherent beam propagating through an astigmatic ABCD optical system with loss or gain.

    Science.gov (United States)

    Cai, Yangjian; Zhu, Shijun

    2014-04-01

    We derive the general expression for the orbital angular momentum (OAM) flux of an astigmatic partially coherent beam carrying twist phase [i.e., twisted anisotropic Gaussian-Schell model (TAGSM) beam] propagating through an astigmatic ABCD optical system with loss or gain. The evolution properties of the OAM flux of a TAGSM beam in a Gaussian cavity or propagating through a cylindrical thin lens are illustrated numerically with the help of the derived formula. It is found that we can modulate the OAM of a partially coherent beam by varying the parameters of the cavity or the orientation angle of the cylindrical thin lens, which will be useful in some applications, such as free-space optical communications and particle trapping.

  5. Visual acuity and pattern of visual field loss at presentation in pituitary adenoma.

    Science.gov (United States)

    Ogra, Siddharth; Nichols, Andrew D; Stylli, Stanley; Kaye, Andrew H; Savino, Peter J; Danesh-Meyer, Helen V

    2014-05-01

    Our purpose was to analyse the demographics, prevalence and pattern of visual field defects in patients with pituitary adenoma. We prospectively recruited 103 consecutive patients (206 eyes) presenting to a neurosurgical unit with pituitary adenoma. Ophthalmological examination and standard automated perimetry (Humphrey, 24-2 threshold) was performed. Severity of visual field defects was also assessed. The mean population age was 53.9 years (standard deviation=15). Visual loss was the most common reason for presentation (39%) followed by endocrine abnormality (21%) and headache (15%). Patients with endocrine abnormality on presentation were 10.9 years younger than those presenting with visual loss (p=0.001). Bitemporal defects were the most prevalent pattern (n=22, 41%) followed by homonymous defects (n=7, 13%). Of the patients with visual field loss, 33% had unilateral visual field defects. The mean visual acuity in those with bitemporal defects was 6/7.5 with half of these patients having 6/6 vision in both eyes. In conclusion, the majority of patients with pituitary adenoma have visual acuity better than 6/7.5 despite having visual field defects. While a bitemporal pattern of visual field loss is the most common, a significant proportion of patients had unilateral and altitudinal defects. Assessment of the visual field is essential to rule out chiasmal compression.

  6. Low-resistance strip sensors for beam-loss event protection

    Energy Technology Data Exchange (ETDEWEB)

    Ullán, M., E-mail: Miguel.Ullan@imb-cnm.csic.es [Centro Nacional de Microelectrónica (IMB-CNM, CSIC), Campus Universitario de Bellaterra, 08193 Barcelona (Spain); Benítez, V.; Quirion, D.; Zabala, M.; Pellegrini, G.; Lozano, M. [Centro Nacional de Microelectrónica (IMB-CNM, CSIC), Campus Universitario de Bellaterra, 08193 Barcelona (Spain); Lacasta, C.; Soldevila, U.; García, C. [Instituto de Fisica Corpuscular (IFIC, CSIC-UV), Valencia (Spain); Fadeyev, V.; Wortman, J.; DeFilippis, J.; Shumko, M.; Grillo, A.A; Sadrozinski, H.F.-W. [Santa Cruz Institute for Particle Physics (SCIPP), University of California Santa Cruz (UCSC), Santa Cruz, CA (United States)

    2014-11-21

    AC-coupled silicon strip sensors can be damaged in case of a beam loss due to the possibility of a large charge accumulation in the bulk, developing very high voltages across the coupling capacitors which can destroy them. Punch-through structures are currently used to avoid this problem helping to evacuate the accumulated charge as large voltages are developing. Nevertheless, previous experiments, performed with laser pulses, have shown that these structures can become ineffective in relatively long strips. The large value of the implant resistance can effectively isolate the “far” end of the strip from the punch-through structure leading to large voltages. We present here our developments to fabricate low-resistance strip sensors to avoid this problem. The deposition of a conducting material in contact with the implants drastically reduces the strip resistance, assuring the effectiveness of the punch-through structures. First devices have been fabricated with this new technology. Initial results with laser tests show the expected reduction in peak voltages on the low resistivity implants. Other aspects of the sensor performance, including the signal formation, are not affected by the new technology.

  7. Localization of the large-angle foil-scattering beam loss caused by the multiturn charge-exchange injection

    Science.gov (United States)

    Kato, Shinichi; Yamamoto, Kazami; Yoshimoto, Masahiro; Harada, Hiroyuki; Kinsho, Michikazu

    2013-07-01

    In the 3 GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex, significant losses were observed at the branching of the H0 dump line and the beam position monitor that was inserted downstream of the H0 dump branch duct. These losses were caused by the large-angle scattering of the injection and circulating beams at the charge-exchange foil. To realize high-power operation, these losses must be mitigated. Therefore, a new collimation system was developed and installed in October 2011. To efficiently optimize this system, the behavior of particles scattered by the foil and produced by the absorber were simulated, and the optimal position and angle of the absorber were investigated. During this process, an angle regulation method for the absorber was devised. An outline of this system, the angle regulation method for the absorber, and the performance of this new collimation system are described.

  8. Proof of concept demonstration for coherent beam pattern measurements of KID detectors

    Science.gov (United States)

    Davis, Kristina K.; Baryshev, Andrey M.; Jellema, Willem; Yates, Stephen J. C.; Ferrari, Lorenza; Baselmans, Jochem J. A.

    2016-07-01

    Here we summarize the initial results from a complex field radiation pattern measurement of a kinetic inductance detector instrument. These detectors are phase insensitive and have thus been limited to scalar, or amplitude-only, beam measurements. Vector beam scans, of both amplitude and phase, double the information received in comparison to scalar beam scans. Scalar beam measurements require multiple scans at varying distances along the optical path of the receiver to fully constrain the divergence angle of the optical system and locate the primary focus. Vector scans provide this information with a single scan, reducing the total measurement time required for new systems and also limiting the influence of system instabilities. The vector scan can be taken at any point along the optical axis of the system including the near-field, which makes beam measurements possible for large systems at high frequencies where these measurements may be inconceivable to be tested in-situ. Therefore, the methodology presented here should enable common heterodyne analysis for direct detector instruments. In principle, this coherent measurement strategy allows phase dependent analysis to be performed on any direct-detect receiver instrument.

  9. Crossover patterning by the beam-film model: analysis and implications.

    Directory of Open Access Journals (Sweden)

    Liangran Zhang

    2014-01-01

    Full Text Available Crossing-over is a central feature of meiosis. Meiotic crossover (CO sites are spatially patterned along chromosomes. CO-designation at one position disfavors subsequent CO-designation(s nearby, as described by the classical phenomenon of CO interference. If multiple designations occur, COs tend to be evenly spaced. We have previously proposed a mechanical model by which CO patterning could occur. The central feature of a mechanical mechanism is that communication along the chromosomes, as required for CO interference, can occur by redistribution of mechanical stress. Here we further explore the nature of the beam-film model, its ability to quantitatively explain CO patterns in detail in several organisms, and its implications for three important patterning-related phenomena: CO homeostasis, the fact that the level of zero-CO bivalents can be low (the "obligatory CO", and the occurrence of non-interfering COs. Relationships to other models are discussed.

  10. Influence of the beam-size effect on particle losses at B-factories PEP-II and KEKB

    Energy Technology Data Exchange (ETDEWEB)

    Kotkin, G.L.; Serbo, V.G. E-mail: serbo@math.nsc.ru

    2004-01-21

    In the colliders, the macroscopically large impact parameters give a substantial contribution to the standard cross-section of the e{sup +}e{sup -}{yields}e{sup +}e{sup -}{gamma} process. These impact parameters may be much larger than the transverse sizes of the colliding bunches. It means that the standard cross-section of this process has to be substantially modified. In the present paper such a beam-size is calculated for bremsstrahlung at B-factories PEP-II and KEKB. We find out that this effect reduces beam losses due to bremsstrahlung by about 20%.

  11. Patterns of houses and habitat loss from 1937 to 1999 in northern Wisconsin, USA.

    Science.gov (United States)

    Gonzalez-Abraham, Charlotte E; Radeloff, Volker C; Hawbaker, Todd J; Hammer, Roger B; Stewart, Susan I; Clayton, Murray K

    2007-10-01

    Rural America is witnessing widespread housing development, which is to the detriment of the environment. It has been suggested to cluster houses so that their disturbance zones overlap and thus cause less habitat loss than is the case for dispersed development. Clustering houses makes intuitive sense, but few empirical studies have quantified the spatial pattern of houses in real landscapes, assessed changes in their patterns over time, and quantified the resulting habitat loss. We addressed three basic questions: (1) What are the spatial patterns of houses and how do they change over time; (2) How much habitat is lost due to houses, and how is this affected by spatial pattern of houses; and (3) What type of habitat is most affected by housing development. We mapped 27 419 houses from aerial photos for five time periods in 17 townships in northern Wisconsin and calculated the terrestrial land area remaining after buffering each house using 100- and 500-m disturbance zones. The number of houses increased by 353% between 1937 and 1999. Ripley's K test showed that houses were significantly clustered at all time periods and at all scales. Due to the clustering, the rate at which habitat was lost (176% and 55% for 100- and 500-m buffers, respectively) was substantially lower than housing growth rates, and most land area was undisturbed (95% and 61% for 100-m and 500-m buffers, respectively). Houses were strongly clustered within 100 m of lakes. Habitat loss was lowest in wetlands but reached up to 60% in deciduous forests. Our results are encouraging in that clustered development is common in northern Wisconsin, and habitat loss is thus limited. However, the concentration of development along lakeshores causes concern, because these may be critical habitats for many species. Conservation goals can only be met if policies promote clustered development and simultaneously steer development away from sensitive ecosystems.

  12. Classifying performance impairment in response to sleep loss using pattern recognition algorithms on single session testing.

    Science.gov (United States)

    St Hilaire, Melissa A; Sullivan, Jason P; Anderson, Clare; Cohen, Daniel A; Barger, Laura K; Lockley, Steven W; Klerman, Elizabeth B

    2013-01-01

    There is currently no "gold standard" marker of cognitive performance impairment resulting from sleep loss. We utilized pattern recognition algorithms to determine which features of data collected under controlled laboratory conditions could most reliably identify cognitive performance impairment in response to sleep loss using data from only one testing session, such as would occur in the "real world" or field conditions. A training set for testing the pattern recognition algorithms was developed using objective Psychomotor Vigilance Task (PVT) and subjective Karolinska Sleepiness Scale (KSS) data collected from laboratory studies during which subjects were sleep deprived for 26-52h. The algorithm was then tested in data from both laboratory and field experiments. The pattern recognition algorithm was able to identify performance impairment with a single testing session in individuals studied under laboratory conditions using PVT, KSS, length of time awake and time of day information with sensitivity and specificity as high as 82%. When this algorithm was tested on data collected under real-world conditions from individuals whose data were not in the training set, accuracy of predictions for individuals categorized with low performance impairment were as high as 98%. Predictions for medium and severe performance impairment were less accurate. We conclude that pattern recognition algorithms may be a promising method for identifying performance impairment in individuals using only current information about the individual's behavior. Single testing features (e.g., number of PVT lapses) with high correlation with performance impairment in the laboratory setting may not be the best indicators of performance impairment under real-world conditions. Pattern recognition algorithms should be further tested for their ability to be used in conjunction with other assessments of sleepiness in real-world conditions to quantify performance impairment in response to sleep loss.

  13. Growth of GaN based structures on focused ion beam patterned templates

    Energy Technology Data Exchange (ETDEWEB)

    Cordier, Y.; Tottereau, O.; Nguyen, L. [Centre de Recherche sur l' Heteroepitaxie et ses Application, UPR-CNRS, Valbonne (France); Ramdani, M.; Soltani, A.; Boucherit, M.; Troadec, D.; Lo, F.Y.; Hu, Y.Y.; Ludwig, A.; Wieck, A.D. [Centre de Recherche sur l' Heteroepitaxie et ses Application, UPR-CNRS, Valbonne (France); Institut d' Electronique, de Microelectronique et de Nanotechnologie, Cite Scientifique, Villeneuve d' Ascq (France); Lehrstuhl fuer Angewandte Festkoerperphysik, Ruhr-Universitaet Bochum (Germany)

    2011-05-15

    Focused ion beam technique is a powerful tool for defining patterns within a semiconductor film. In this paper, we show that it is possible to realize patterns such as disks and columns within thick GaN templates and that it is compatible with the regrowth of GaN based heterostructures. We study the effect of the pattern size and shape on the regrowth by molecular beam epitaxy. We show that the growth using ammonia as the nitrogen source with flux at temperature optimized for 2-dimensional growth leads to the apparition of well defined growth planes. We show that the development of these planes is dependent with the initial pattern size and shape. These results confirm the difficulty for realizing micro or nano-columns with axial heterostructures. At the opposite, these growth conditions seem favourable for core-shell heterostructures column with well defined m-plane and eventually a-plane lateral facets. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Conserving Biogeography: Habitat Loss and Vicariant Patterns in Endemic Squamates of the Cerrado Hotspot.

    Science.gov (United States)

    de Mello, Pietro L H; Machado, Ricardo B; Nogueira, Cristiano de C

    2015-01-01

    Little is known about the threat levels and impacts of habitat loss over the Cerrado Squamate fauna. The region is under severe habitat loss due to mechanized agriculture, accelerated by changes in the Brazilian National Forest Code. The Squamate fauna of the Cerrado is rich in endemics and is intrinsically associated with its surrounding microhabitats, which make up a mosaic of phitophysiognomies throughout the region. Herein we evaluate current conservation status of Squamate biogeographic patterns in the Brazilian Cerrado, the single savanna among global biodiversity hotspots. To do so, we first updated point locality data on 49 endemic Squamates pertaining to seven non-random clusters of species ranges in the Cerrado. Each cluster was assumed to be representative of different biogeographic regions, holding its own set of species, herein mapped according to their extent of occurrence (EOO). We then contrasted these data in four different scenarios, according to the presence or absence of habitat loss and the presence or absence of the current protected area (PA) cover. We searched for non-random patterns of habitat loss and PA coverage among these biogeographic regions throughout the Cerrado. Finally, with the species EOO as biodiversity layers, we used Zonation to discuss contemporary PA distribution, as well as to highlight current priority areas for conservation within the Cerrado. We ran Zonation under all four conservation scenarios mentioned above. We observed that habitat loss and PA coverage significantly differed between biogeographic regions. The southernmost biogeographic region is the least protected and the most impacted, with priority areas highly scattered in small, disjunct fragments. The northernmost biogeographic region (Tocantins-Serra Geral) is the most protected and least impacted, showing extensive priority areas in all Zonation scenarios. Therefore, current and past deforestation trends are severely threatening biogeographic patterns in

  15. Effective beam pattern of the Blainville's beaked whale (Mesoplodon densirostris) and implications for passive acoustic monitoring.

    Science.gov (United States)

    Shaffer, Jessica Ward; Moretti, David; Jarvis, Susan; Tyack, Peter; Johnson, Mark

    2013-03-01

    The presence of beaked whales in mass-strandings coincident with navy maneuvers has prompted the development of methods to detect these cryptic animals. Blainville's beaked whales, Mesoplodon densirostris, produce distinctive echolocation clicks during long foraging dives making passive acoustic detection a possibility. However, performance of passive acoustic monitoring depends upon the source level, beam pattern, and clicking behavior of the whales. In this study, clicks recorded from Digital acoustic Tags (DTags) attached to four M. densirostris were linked to simultaneous recordings from an 82-hydrophone bottom-mounted array to derive the source level and beam pattern of the clicks, as steps towards estimating their detectability. The mean estimated on-axis apparent source level for the four whales was 201 dBrms97. The mean 3 dB beamwidth and directivity index, estimated from sequences of clicks directed towards the far-field hydrophones, were 13° and 23 dB, respectively. While searching for prey, Blainville's beaked whales scan their heads horizontally at a mean rate of 3.6°/s over an angular range of some +/-10°. Thus, while the DI indicates a narrow beam, the area of ensonification over a complete foraging dive is large given the combined effects of body and head movements associated with foraging.

  16. Direct patterning of gold oxide thin films by focused ion-beam irradiation

    Science.gov (United States)

    Machalett, F.; Edinger, K.; Melngailis, J.; Diegel, M.; Steenbeck, K.; Steinbeiss, E.

    For direct writing of electrically conducting connections and areas into insulating gold oxide thin films a scanning Ar+ laser beam and a 30 keV Ga+ focused ion beam (FIB) have been used. The gold oxide films are prepared by magnetron sputtering under argon/oxygen plasma. The patterning of larger areas (dimension 10-100 μm) has been carried out with the laser beam by local heating of the selected area above the decomposition temperature of AuOx (130-150 °C). For smaller dimensions (100 nm to 10 μm) the FIB irradiation could be used. With both complementary methods a reduction of the sheet resistance by 6-7 orders of magnitude has been achieved in the irradiated regions (e.g. with FIB irradiation from 1.5×107 Ω/□ to approximately 6 Ω/□). The energy-dispersive X-ray analysis (EDX) show a considerably reduced oxygen content in the irradiated areas, and scanning electron microscopy (SEM), as well as atomic force microscopy (AFM) investigations, indicate that the FIB patterning in the low-dose region (1014 Ga+/cm2) is combined with a volume reduction, which is caused by oxygen escape rather than by sputtering.

  17. Analysis of the Pipe Heat Loss of the Water Flow Calorimetry System in EAST Neutral Beam Injector

    Science.gov (United States)

    Hu, Chundong; Chen, Yu; Xu, Yongjian; Yu, Ling; Li, Xiang; Zhang, Weitang

    2016-11-01

    Neutral beam injection heating is one of the main auxiliary heating methods in controllable nuclear fusion research. In the EAST neutral beam injector, a water flow calorimetry (WFC) system is applied to measure the heat load on the electrode system of the ion source and the heat loading components of the beamline. Due to the heat loss in the return water pipe, there are some measuring errors for the current WFC system. In this paper, the errors were measured experimentally and analyzed theoretically, which lay a basis for the exact calculation of beam power deposition distribution and neutralization efficiency. supported by the National Magnetic Confinement Fusion Science Program of China (No. 2013GB101001) and the International Science & Technology Cooperation Program of China (No. 2014DFG61950)

  18. Comparison of three different concepts of high dynamic range and dependability optimised current measurement digitisers for beam loss systems

    CERN Document Server

    Viganò, W; Effinger, E; Venturini, G G; Zamantzas, C

    2012-01-01

    Three Different Concepts of High Dynamic Range and Dependability Optimised Current Measurement Digitisers for Beam Loss Systems will be compared on this paper. The first concept is based on Current to Frequency Conversion, enhanced with an ADC for extending the dynamic range and decreasing the response time. A summary of 3 years’ worth of operational experience with such a system for LHC beam loss monitoring will be given. The second principle is based on an Adaptive Current to Frequency Converter implemented in an ASIC. The basic parameters of the circuit are discussed and compared with measurements. Several measures are taken to harden both circuits against single event effects and to make them tolerant for operation in radioactive environments. The third circuit is based on a Fully Differential Integrator for enhanced dynamic range, where laboratory and test installation measurements will be presented. All circuits are designed to avoid any dead time in the acquisition and have reliability and fail safe...

  19. Calculation of abort thresholds for the Beam Loss Monitoring System of the Large Hadron Collider at CERN

    CERN Document Server

    Nemcic, Martin; Dehning, Bernd

    The Beam Loss Monitoring (BLM) System is one of the most critical machine protection systems for the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN), Switzerland. Its main purpose is to protect the superconducting magnets from quenches and other equipment from damage by requesting a beam abort when the measured losses exceed any of the predefined threshold levels. The system consist of circa 4000 ionization chambers which are installed around the 27 kilometres ring (LHC). This study aims to choose a technical platform and produce a system that addresses all of the limitations with the current system that is used for the calculation of the LHC BLM abort threshold values. To achieve this, a comparison and benchmarking of the Java and .NET technical platforms is performed in order to establish the most suitable solution. To establish which technical platform is a successful replacement of the current abort threshold calculator, comparable prototype systems in Java and .NET we...

  20. Process time optimization of robotic remote laser cutting by utilizing customized beam patterns and redundancy space task sequencing

    DEFF Research Database (Denmark)

    Villumsen, Sigurd

    This dissertation is written as a part of the ROBOCUT project which concerns the development of a new laser cutting technology that seeks to increase the performance of traditional and remote laser cutting by using beam shaping technologies. The resulting customized beam patterns are obtained by ...... axes of the laser cutting system and transforming the sequencing problem into a generalized traveling salesman problem (GTSP)....

  1. Design and construction of the first prototype ionization chamber for CSNS and PA beam loss monitor (BLM) system

    Institute of Scientific and Technical Information of China (English)

    XU Mei-Hang; TIAN Jian-Min; CHEN Chang; CHEN Yuan-Bo; XU Tao-Guang; LU Shuang-Tong

    2009-01-01

    Design and construction of the first prototype ionization chamber for CSNS and Proton Accelerator (PA) beam loss monitor (BLM) system is reported. The low leakage current (<0.1 pA), good plateau (≈800 V) and linearity range up to 200 Roentgen/h axe obtained in the first prototype. All of these give us good experience for further improving the ionization chamber construction.

  2. Dynamic topography of pattern visual evoked potentials (PVEP) in psychogenic visual loss patients.

    Science.gov (United States)

    Nakamura, A; Tabuchi, A; Matsuda, E; Yamaguchi, W

    2000-09-01

    We investigated to measure the objective visual acuity using pattern visual evoked potentials (PVEP) to help the diagnosis with psychogenic visual loss (PVL) who ranged in age from 7 to 14 years old. Pattern stimuli consisted of black and white checkerboard patterns (39, 26, 15 and 9') with a visual angle of 8 degrees and a contrast level of 15%. The pattern reversal frequency was 0.7 Hz. This resulted in an average of 100 PVEP per session. Visual acuity of 0.1 was consistent with the 39' pattern, 0.2 with the 26' pattern, 0.5 with the 15' pattern, and 1.0 with the 9' pattern. As the results, five PVL patients could measure visual acuity with this method in the present study. The PVEP is useful in evaluating the visual acuity and helped to diagnose the PVL patients. In addition we used the dynamic topography to study the difference in the results of the PVEP. The dynamic topography obtained from the results of the PVEP was analyzed. The flow type of the P100 component diverged into three types (separated type, hollow type and localized type) in the PVL patients and the normal children. The localized type was observed in 59.1% of normal children and in 56.3% of PVL patients. While the separated type was shown in 6.8% of normal children and in 8.3% of PVL patients. There were not significant differences between the PVL patients and the normal children in each type.

  3. A novel digitization scheme with FPGA-base TDC for beam loss monitors operating at cryogenic temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jinyuan; Warner, Arden; /Fermilab

    2011-11-01

    Recycling integrators are common current-to-frequency converting circuits for measurements of low current such as that produced by Fermilab's cryogenic ionization chambers. In typical digitization/readout schemes, a counter is utilized to accumulate the number of pulses generated by the recycling integrator to adequately digitize the total charge. In order to calculate current with reasonable resolution (e.g., 7-8 bits), hundreds of pulses must be accumulated which corresponds to a long sampling period, i.e., a very low sampling rate. In our new scheme, an FPGA-based Time-to-Digital Convertor (TDC) is utilized to measure the time intervals between the pulses output from the recycling integrator. Using this method, a sample point of the current can be made with good resolution (>10 bits) for each pulse. This effectively increases the sampling rates by hundreds of times for the same recycling integrator front-end electronics. This scheme provides a fast response to the beams loss and is potentially suitable for accelerator protection applications. Moreover, the method is also self-zero-suppressed, i.e., it produces more data when the beam loss is high while it produces significantly less data when the beam loss is low.

  4. Patterning of Aluminium thin film on polyethylene terephthalate by multi-beam picosecond laser

    Science.gov (United States)

    Jin, Y.; Perrie, W.; Harris, P.; Allegre, O. J.; Abrams, K. J.; Dearden, G.

    2015-11-01

    High speed patterning of a 30 nm thick Aluminium thin film on a flexible Polyethylene Terephthalate substrate was demonstrated with the aid of Computer Generated Holograms (CGH's) applied to a phase only Spatial Light Modulator. Low fluence picosecond laser pulses minimise thermal damage to the sensitive substrate and thus clean, single and multi-beam, front side thin film removal is achieved with good edge quality. Interestingly, rear side ablation shows significant Al film delamination. Measured front and rear side ablation thresholds were Fth=0.20±0.01 J cm-2 and Fth=0.15±0.01 J cm-2 respectively. With laser repetition rate of 200 kHz and 8 diffractive spots, a film removal rate of R>0.5 cm2 s-1 was demonstrated during patterning with a fixed CGH and 5 W average laser power. The effective laser repetition rate was feff~1.3 MHz. The application of 30 stored CGH's switching up to 10 Hz was also synchronised with motion control, allowing dynamic large area multi-beam patterning which however, slows micro-fabrication.

  5. Enhanced e-beam pattern writing for nano-optics based on character projection

    Science.gov (United States)

    Kley, E.-Bernhard; Schmidt, Holger; Zeitner, Uwe; Banasch, Michael; Schnabel, Bernd

    2012-02-01

    The pattern generation for nano-optics raises high demands on resolution, writing speed and flexibility: nearly arbitrary complex structures with feature sizes below 100 nm should be realized on large areas up to 9 inches in square within reasonable time. With e-beam lithography the requirements on resolution and flexibility can be fulfilled but the writing time becomes the bottle neck. Acceleration by Variable Shaped Beam (VSB) writing principle (geometrical primitives with flexible size can be exposed with a single shot) is sometimes not sufficient. Character Projection (CP) is able to speed up the writing drastically because complex pattern of a limited area can be exposed by one shot [1]. We tested CP in the Vistec SB350 OS for optical applications and found a shot count reduction up to 1/1000, especially for geometries which are hard to approximate by geometrical primitives. Additionally, the resolution and the pattern quality were influenced in a positive way. Another benefit is the possibility to spend a part of the gain in writing speed to the use of a high resolution but low sensitive resist like HSQ. The tradeoff between speed and flexibility should be compensable by a large number of characters available.

  6. Mitigating illumination gradients in a SAR image based on the image data and antenna beam pattern

    Science.gov (United States)

    Doerry, Armin W.

    2013-04-30

    Illumination gradients in a synthetic aperture radar (SAR) image of a target can be mitigated by determining a correction for pixel values associated with the SAR image. This correction is determined based on information indicative of a beam pattern used by a SAR antenna apparatus to illuminate the target, and also based on the pixel values associated with the SAR image. The correction is applied to the pixel values associated with the SAR image to produce corrected pixel values that define a corrected SAR image.

  7. Significant reduction of AC losses in YBCO patterned coated conductors with transposed filaments

    Energy Technology Data Exchange (ETDEWEB)

    Abraimov, Dmytro; Gurevich, Alex; Polyanskii, Anatolii; Cai, X Y; Xu, Aixia; Larbalestier, David [Applied Superconductivity Center at the National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL (United States); Pamidi, Sastry [Center for Advanced Power Systems, Florida State University, Tallahassee, FL (United States); Thieme, C L H [American Superconductor Corporation, Devens, MA (United States)

    2008-08-15

    We report on a first implementation of a design which provides a significant reduction of AC losses in YB{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) coated conductors (CCs) without mechanical twisting. The conductor is composed of two diffusively bonded silver clad commercial CCs with zigzag patterned filaments partially separated by a dielectric layer. We produced three fully bonded samples with 500 {mu}m wide filaments using three-stage photolithography and wet chemical etching. A tenfold reduction of AC losses at frequencies between 20 and 400 Hz was observed, while transport measurements and magneto-optical imaging showed no degradation of T{sub c} and a low contact resistance of {approx_equal}10{sup -8} {omega}cm{sup 2} between Ag and YB{sub 2}Cu{sub 3}O{sub 7-{delta}}. (rapid communication)

  8. Estimation of propagation losses for infrared laser beam in turbulent atmosphere

    Science.gov (United States)

    Zaponov, A. E.; Sakharov, M. V.

    2016-11-01

    In present work, the radiation propagation in atmosphere from laser source to the receiver is considered by taking into account deviations of optical beam due to turbulence. The photon flux density on the receiver has been evaluated.

  9. Energy loss of intergalactic pair beams: Particle-in-Cell simulation

    CERN Document Server

    Kempf, Andreas; Spanier, Felix

    2016-01-01

    The change of the distribution function of electron-positron pair beams determines whether GeV photons can be produced as secondary radiation from TeV photons. We will discuss the instabilities driven by pair beams. The system of a thermal proton-electron plasma and the electron-positron beam is collision free. We have, therefore, used the Particle-in-Cell simulation approach. It was necessary to alter the physical parameters, but the ordering of growth rates has been retained. We were able to show that plasma instabilities can be recovered in particle-in-cell simulations, but their effect on the pair distribution function is negligible for beam-background energy density ratios typically found in blazars.

  10. Complex suppression patterns distinguish between major energy loss effects in Quark-Gluon Plasma

    CERN Document Server

    Djordjevic, Magdalena

    2015-01-01

    Interactions of high momentum partons with Quark-Gluon Plasma created in relativistic heavy-ion collisions provide an excellent tomography tool for this new form of matter. Recent measurements for charged hadrons and unidentified jets at the LHC show an unexpected flattening of the suppression curves at high momentum, exhibited when either momentum or the collision centrality is changed. Furthermore, a limited data available for B probes indicate a qualitatively different pattern, as nearly the same flattening is exhibited for the curves corresponding to two opposite momentum ranges. We here show that the experimentally measured suppression curves are well reproduced by our theoretical predictions, and that the complex suppression patterns are due to an interplay of collisional, radiative energy loss and the dead-cone effect. Furthermore, for B mesons, we predict that the uniform flattening of the suppression indicated by the limited dataset is in fact valid across the entire span of the momentum ranges, whic...

  11. Micro-nanopores fabricated by high-energy electron beam irradiation: suitable structure for controlling pesticide loss.

    Science.gov (United States)

    Xiang, Yubin; Wang, Ning; Song, Jimei; Cai, Dongqing; Wu, Zhengyan

    2013-06-01

    Pesticide sprayed onto crop leaves tends to be washed off by rainwater and discharge into the environment through leaching and runoff, resulting in severe pollution to both soil and water. Here, to control pesticide loss, we developed a loss-control pesticide (LCP) by adding modified natural nanoclay (diatomite) through high-energy electron beam (HEEB) to traditional pesticide. After HEEB treatment, the originally clogged pores in diatomite opened, resulting in plenty of micro-nanopores in diatomite, which are beneficial for the pesticide molecules to access and be adsorbed. This pesticide-diatomite complex tended to be retained by the rough surface of crop leaves, displaying a high adhesion performance onto the leaves, so that the pesticide loss reduced, sufficient pesticide for crops was supplied, and the pollution risk of the pesticide could be substantially lowered.

  12. Extremum-seeking control of the beam pattern of a reconfigurable holographic metamaterial antenna.

    Science.gov (United States)

    Johnson, Mikala C; Brunton, Steven L; Kundtz, Nathan B; Kutz, Nathan J

    2016-01-01

    Robust, continuous, and software-defined beam pattern control of holographic metamaterial antennas is necessary to realize the potential of these low-power-consumption, thin, lightweight, inexpensive antennas for consumer usage of satellite communication. We present a complete feedback control approach that enables adaptive control of the radiation pattern for the electronically scanned metamaterial antenna that is robust to measurement noise and is able to continuously optimize performance throughout changing environmental conditions and antenna characteristics. The physical size, weight, and cost advantages of the metamaterial antenna make it an attractive technology when paired with robust and adaptive on-board software strategies to optimize antenna performance and self-tune for various environmental conditions.

  13. Focused ion beam patterning to dielectrophoretically assemble single nanowire based devices

    Energy Technology Data Exchange (ETDEWEB)

    La Ferrara, V; Massera, E; Francia, G Di [ENEA Research Center, P.le E. Fermi 1, 80055 Portici (Italy); Alfano, B, E-mail: vera.laferrara@portici.enea.i [University of Naples ' Federico II' , P.le Tecchio 80, 80125 Naples (Italy)

    2010-02-01

    Direct-write processing is increasingly taking place in nanodevice fabrication. In this work, Focused Ion Beam (FIB), a powerful tool in maskless micromachining, is used for electrode patterning onto a silicon/silicon nitride substrate. Then a single palladium nanowire is assembled between electrodes by means of dielectrophoresis (DEP). The nanowire morphology depends on the electrode pattern when DEP conditions are fixed. FIB/DEP combination overcomes the problem of nanowire electrical contamination due to gallium ion bombardment and the as-grown nanowire retains its basic electrical properties. Single nanowire based devices have been fabricated with this novel approach and have been tested as hydrogen sensors, confirming the reliability of this technology.

  14. Gully Growth Patterns and Soil Loss under Rainfall at Urban Underground Drainage Construction Site, Uyo

    Directory of Open Access Journals (Sweden)

    O.E. Essien

    2012-08-01

    Full Text Available This study investigated, evaluated and modeled patterns of growth of gully morphometric dimension and soil loss volume under prevailing rainfall on the slopes of land graded for the construction of underground drainage at Uyo but delayed in completion. Land grading at underground (tunnel drainage construction site rendered the exposed surface very impervious but young ephemeral gullies developed due to delays in completion. Data on gully morphometric dimension, soil loss and depth of rainfall were analyzed using SPSS ver. 17 statistical package. Mean gully growth in length, width and depth were different at 2.54±0.86, 0.923±0.29 and 0.41±0.11 m, respectively, yielding 3.87±0.08 m2 as mean volume of soil loss at full stage. Cubic polynomial was best-fit model for growth in length (R2 = 79% and width (R2 = 69% using weekly rainfall for an annual season. All gully sites had constant depth change, better predicted by quadratic (R2 = 13% than linear (R2 = 9% functions. Mean volume of soil loss per unit rainfall amount varied with low, medium and high rainfall amount and was highest at slope bottom (33 cm3/cm and least at the crest (6.99 cm3/cm with R2 = 38-34%. Land grading to impervious sublayer produced constant depth change in all gullies at the sites. The models for morphometric incremental growth and soil loss volume under the rainfall effect was significantly improved (p<0.05 by bifurcating the lumped annual curve into two growth periods in a year: the periods for increasing rainfall (from week 10-30 and for receding rainfall (from week 31-43 in a year and applying quadratic regressing functions on each (R2 = 91-99%. Rainfall was the principal gully factor and construction delays should be avoided.

  15. Millimeter Wave MIMO Channel Estimation Using Overlapped Beam Patterns and Rate Adaptation

    Science.gov (United States)

    Kokshoorn, Matthew; Chen, He; Wang, Peng; Li, Yonghui; Vucetic, Branka

    2017-02-01

    This paper is concerned with the channel estimation problem in Millimeter wave (mmWave) wireless systems with large antenna arrays. By exploiting the inherent sparse nature of the mmWave channel, we first propose a fast channel estimation (FCE) algorithm based on a novel overlapped beam pattern design, which can increase the amount of information carried by each channel measurement and thus reduce the required channel estimation time compared to the existing non-overlapped designs. We develop a maximum likelihood (ML) estimator to optimally extract the path information from the channel measurements. Then, we propose a novel rate-adaptive channel estimation (RACE) algorithm, which can dynamically adjust the number of channel measurements based on the expected probability of estimation error (PEE). The performance of both proposed algorithms is analyzed. For the FCE algorithm, an approximate closed-form expression for the PEE is derived. For the RACE algorithm, a lower bound for the minimum signal energy-to-noise ratio required for a given number of channel measurements is developed based on the Shannon-Hartley theorem. Simulation results show that the FCE algorithm significantly reduces the number of channel estimation measurements compared to the existing algorithms using non-overlapped beam patterns. By adopting the RACE algorithm, we can achieve up to a 6dB gain in signal energy-to-noise ratio for the same PEE compared to the existing algorithms.

  16. In situ radiation test of silicon and diamond detectors operating in superfluid helium and developed for beam loss monitoring

    Science.gov (United States)

    Kurfürst, C.; Dehning, B.; Sapinski, M.; Bartosik, M. R.; Eisel, T.; Fabjan, C.; Rementeria, C. A.; Griesmayer, E.; Eremin, V.; Verbitskaya, E.; Zabrodskii, A.; Fadeeva, N.; Tuboltsev, Y.; Eremin, I.; Egorov, N.; Härkönen, J.; Luukka, P.; Tuominen, E.

    2015-05-01

    As a result of the foreseen increase in the luminosity of the Large Hadron Collider, the discrimination between the collision products and possible magnet quench-provoking beam losses of the primary proton beams is becoming more critical for safe accelerator operation. We report the results of ongoing research efforts targeting the upgrading of the monitoring system by exploiting Beam Loss Monitor detectors based on semiconductors located as close as possible to the superconducting coils of the triplet magnets. In practice, this means that the detectors will have to be immersed in superfluid helium inside the cold mass and operate at 1.9 K. Additionally, the monitoring system is expected to survive 20 years of LHC operation, resulting in an estimated radiation fluence of 1×1016 proton/cm2, which corresponds to a dose of about 2 MGy. In this study, we monitored the signal degradation during the in situ irradiation when silicon and single-crystal diamond detectors were situated in the liquid/superfluid helium and the dependences of the collected charge on fluence and bias voltage were obtained. It is shown that diamond and silicon detectors can operate at 1.9 K after 1×1016 p/cm2 irradiation required for application as BLMs, while the rate of the signal degradation was larger in silicon detectors than in the diamond ones. For Si detectors this rate was controlled mainly by the operational mode, being larger at forward bias voltage.

  17. Multi-mirror imaging optics for low-loss transport of divergent neutron beams and tailored wavelength spectra

    CERN Document Server

    Zimmer, Oliver

    2016-01-01

    A neutron optical transport system is proposed which comprises nested short elliptical mirrors located halfway between two common focal points M and M'. It images cold neutrons from a diverging beam or a source with finite size at M by single reflections onto a spot of similar size at M'. Direct view onto the neutron source is blocked by a central absorber with little impact on the transported solid angle. Geometric neutron losses due to source size can be kept small using modern supermirrors and distances M-M' of a few tens of metres. Very short flat mirrors can be used in practical implementations. Transport with a minimum of reflections remedies losses due to multiple reflections that are common in long elliptical neutron guides. Moreover, well-defined reflection angles lead to new possibilities for enhancing the spectral quality of primary beams, such as clear-cut discrimination of short neutron wavelengths or beam monochromation using bandpass supermirrors. Multi-mirror imaging systems may thus complemen...

  18. FLOW PATTERN AND PRESSURE LOSS OF OIL-WATER TWO-PHASE FLOW IN HORIZONTAL STEEL PIPE

    Institute of Scientific and Technical Information of China (English)

    CHEN Jie; YAN Da-fan; ZHAO Jing-mei; AN Wei-jie; YAN Da-chun

    2005-01-01

    Experimental Study on oil-water two-phase flow patterns and pressure loss was conducted on a horizontal steel pipe loop with 26.1mm inner diameter and 30m total length.The working fluids are white oil, diesel oil and tap water.Several instruments, including a new type of liquid-probe are successfully integrated to identify 7 different flow patterns.The characteristics of the flow patterns and the transition process were observed and depicted in this paper.Investigation revealed that the pressure loss was mainly depended on the flow patterns.

  19. E-beam nano-patterning for the ordered growth of GaN/InGaN nanorods

    OpenAIRE

    Barbagini, Francesca; Bengoechea-Encabo, Ana; Albert, Steven; Lefebvre, Pierre; Martinez, Javier; Sanchez-Garcia, Miguel Angel; Trampert, Achim; Calleja, Enrique

    2012-01-01

    International audience; E-beam lithography was used to pattern a titanium mask on a GaN substrate with ordered arrays of nanoholes. This patterned mask served as a template for the subsequent ordered growth of GaN/InGaN nanorods by plasma-assisted molecular beam epitaxy. The mask patterning process was optimized for several holes configurations. The smallest holes were 30 nm in diameter with a pitch (center-to-center distance) of 100 nm only. High quality masks of several geometries were obta...

  20. Complex suppression patterns distinguish between major energy loss effects in Quark-Gluon Plasma

    Science.gov (United States)

    Djordjevic, Magdalena

    2016-12-01

    Interactions of high momentum partons with Quark-Gluon Plasma created in relativistic heavy-ion collisions provide an excellent tomography tool for this new form of matter. Recent measurements for charged hadrons and unidentified jets at the LHC show an unexpected flattening of the suppression curves at high momentum, exhibited when either momentum or the collision centrality is changed. Furthermore, a limited data available for B probes indicate a qualitatively different pattern, as nearly the same flattening is exhibited for the curves corresponding to two opposite momentum ranges. We here show that the experimentally measured suppression curves are well reproduced by our theoretical predictions, and that the complex suppression patterns are due to an interplay of collisional, radiative energy loss and the dead-cone effect. Furthermore, for B mesons, we predict that the uniform flattening of the suppression indicated by the limited dataset is in fact valid across the entire span of the momentum ranges, which will be tested by the upcoming experiments. Overall, the study presented here, provides a rare opportunity for pQCD theory to qualitatively distinguish between the major energy loss mechanisms at the same (nonintuitive) dataset.

  1. Complex suppression patterns distinguish between major energy loss effects in Quark–Gluon Plasma

    Directory of Open Access Journals (Sweden)

    Magdalena Djordjevic

    2016-12-01

    Full Text Available Interactions of high momentum partons with Quark–Gluon Plasma created in relativistic heavy-ion collisions provide an excellent tomography tool for this new form of matter. Recent measurements for charged hadrons and unidentified jets at the LHC show an unexpected flattening of the suppression curves at high momentum, exhibited when either momentum or the collision centrality is changed. Furthermore, a limited data available for B probes indicate a qualitatively different pattern, as nearly the same flattening is exhibited for the curves corresponding to two opposite momentum ranges. We here show that the experimentally measured suppression curves are well reproduced by our theoretical predictions, and that the complex suppression patterns are due to an interplay of collisional, radiative energy loss and the dead-cone effect. Furthermore, for B mesons, we predict that the uniform flattening of the suppression indicated by the limited dataset is in fact valid across the entire span of the momentum ranges, which will be tested by the upcoming experiments. Overall, the study presented here, provides a rare opportunity for pQCD theory to qualitatively distinguish between the major energy loss mechanisms at the same (nonintuitive dataset.

  2. A general algorithm for calculation of recombination losses in ionization chambers exposed to ion beams

    CERN Document Server

    Christensen, Jeppe brage; Bassler, Niels

    2016-01-01

    Dosimetry with ionization chambers in clinical ion beams for radiation therapy requires correction for recombination effects. However, common radiation protocols discriminate between initial and general recombination and provide no universal correction method for the presence of both recombination types in ion beams of charged particles heavier than protons. Here, we present the open source code IonTracks, where the combined initial and general recombination effects in principle can be predicted for any ion beam with arbitrary particle-energy spectrum and temporal structure. IonTracks uses track structure theory to distribute the charge carriers in ion tracks. The charge carrier movements are governed by a pair of coupled differential equations, based on fundamental physical properties as charge carrier drift, diffusion, and recombination, which are solved numerically while the initial and general charge carrier recombination is computed. The algorithm is numerically stable and in accordance with experimental...

  3. Determination of internal-target thickness and experimental luminosity from beam energy loss at HIRFL-CSRe

    Science.gov (United States)

    Shao, Cao-Jie; Yu, De-Yang; Lu, Rong-Chun; Zhao, Tie-Cheng; Mao, Rui-Shi; Li, Jie; Xue, Ying-Li; Wang, Wei; Yang, Bian; Zhang, Ming-Wu; Liu, Jun-Liang; Song, Zhang-Yong; Cai, Xiao-Hong; Chen, Xi-Meng; Yin, Da-Yu; Mao, Li-Jun; Yang, Xiao-Dong; Yang, Jian-Cheng; Yuan, You-Jin

    2016-11-01

    The target thickness for nitrogen was determined from the beam energy loss in HIRFL-CSRe during the experimental study of the K-REC process in 197 MeV/u Xe54+-N2 collisions. Furthermore, the corresponding integrated luminosity of (1.15±0.06) × 1030 cm-2 was obtained. As an independent check on the energy-loss method, we have also determined the integrated luminosity by measuring the produced X-rays from the K-REC process with a known differential cross section. The values of (1.12±0.06) × 1030 and (1.09±0.06) × 1030 cm-2 were obtained by using two high-purity germanium (HPGe) detectors which were oriented at 90° and 120° with respect to the beam path, respectively. The consistent results confirmed the feasibility of the energy-loss method, which may have an important impact on future internal target experiments at HIRFL-CSRe. Supported by National Natural Science Foundation of China (11179017, 11105201, U1532130, and U1332206)

  4. Modelling the Loss of Steel-Concrete Bonds in Corroded Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    2007-01-01

    The existing stochastic models for deterioration of reinforced concrete structures is extended by adding modelling of "loss of bond" due to corrosion between the reinforcement bars and the surrounding concrete.......The existing stochastic models for deterioration of reinforced concrete structures is extended by adding modelling of "loss of bond" due to corrosion between the reinforcement bars and the surrounding concrete....

  5. Characterization of a wide dynamic-range, radiation-tolerant charge-digitizer asic for monitoring of Beam losses

    CERN Document Server

    Guido Venturini, G G; Dehning, B; Kayal, M

    2012-01-01

    An Application Specific Integrated Circuit (ASIC) has been designed and fabricated to provide a compact solution to digitize current signals from ionization chambers and diamond detectors, employed as beam loss monitors at CERN and several other high energy physics facilities. The circuit topology has been devised to accept positive and negative currents, to have a wide dynamic range (above 120 dB), withstand radiation levels over 10 Mrad and offer different modes of operation, covering a broad range of applications. Furthermore, an internal conversion reference is employed in the digitization, to provide an accurate absolute measurement. This paper discusses the detailed characterization of the first prototype: linearity, radiation tolerance and temperature dependence of the conversion, as well as implications and system-level considerations regarding its use for beam instrumentation applications in a high energy physics facility.

  6. Severe signal loss in diamond beam loss monitors in high particle rate environments by charge trapping in radiation-induced defects

    Energy Technology Data Exchange (ETDEWEB)

    Kassel, Florian; Boer, Wim de [Institute for Experimental Nuclear Physics (IEKP), KIT, Karlsruhe (Germany); Guthoff, Moritz; Dabrowski, Anne [CERN, Meyrin (Switzerland)

    2016-10-15

    The beam condition monitoring leakage (BCML) system is a beam monitoring device in the compact muon solenoid (CMS) experiment at the large hadron collider (LHC). As detectors 32 poly-crystalline (pCVD) diamond sensors are positioned in rings around the beam pipe. Here, high particle rates occur from the colliding beams scattering particles outside the beam pipe. These particles cause defects, which act as traps for the ionization, thus reducing the charge collection efficiency (CCE). However, the loss in CCE was much more severe than expected from low rate laboratory measurements and simulations, especially in single-crystalline (sCVD) diamonds, which have a low initial concentration of defects. After an integrated luminosity of a few fb{sup -1} corresponding to a few weeks of LHC operation, the CCE of the sCVD diamonds dropped by a factor of five or more and quickly approached the poor CCE of pCVD diamonds. The reason why in real experiments the CCE is much worse than in laboratory experiments is related to the ionization rate. At high particle rates the trapping rate of the ionization is so high compared with the detrapping rate, that space charge builds up. This space charge reduces locally the internal electric field, which in turn increases the trapping rate and recombination and hence reduces the CCE in a strongly non-linear way. A diamond irradiation campaign was started to investigate the rate-dependent electrical field deformation with respect to the radiation damage. Besides the electrical field measurements via the transient current technique (TCT), the CCE was measured. The experimental results were used to create an effective deep trap model that takes the radiation damage into account. Using this trap model, the rate-dependent electrical field deformation and the CCE were simulated with the software SILVACO TCAD. The simulation, tuned to rate-dependent measurements from a strong radioactive source, was able to predict the non-linear decrease of the

  7. APT Blanket System Loss-of-Coolant Accident (LOCA) Based on Initial Conceptual Design - Case 2: with Beam Shutdown Only

    Energy Technology Data Exchange (ETDEWEB)

    Hamm, L.L.

    1998-10-07

    This report is one of a series of reports that document normal operation and accident simulations for the Accelerator Production of Tritium (APT) blanket heat removal system. These simulations were performed for the Preliminary Safety Analysis Report. This report documents the results of simulations of a Loss-of-Flow Accident (LOFA) where power is lost to all of the pumps that circulate water in the blanket region, the accelerator beam is shut off and neither the residual heat removal nor cavity flood systems operate.

  8. Combined effects of nuclear and electronic energy losses in solids irradiated with a dual-ion beam

    Science.gov (United States)

    Thomé, Lionel; Debelle, Aurélien; Garrido, Frédérico; Trocellier, Patrick; Serruys, Yves; Velisa, Gihan; Miro, Sandrine

    2013-04-01

    Single and dual-beam irradiations of oxide (c-ZrO2, MgO, Gd2Ti2O7) and carbide (SiC) single crystals were performed to study combined effects of nuclear (Sn) and electronic (Se) energy losses. Rutherford backscattering experiments in channeling conditions show that the Sn/Se cooperation induces a strong decrease of the irradiation-induced damage in SiC and MgO and almost no effects in c-ZrO2 and Gd2Ti2O7. The healing process is ascribed to electronic excitations arising from the electronic energy loss of swift ions. These results present a strong interest for both fundamental understanding of the ion-solid interactions and technological applications in the nuclear industry where expected cooperative Sn/Se effects may lead to the preservation of the integrity of nuclear devices.

  9. Beam losses from ultra-peripheral nuclear collisions between Pb ions in the Large Hadron Collider and their alleviation

    Energy Technology Data Exchange (ETDEWEB)

    Bruce, R.; /CERN; Bocian, D.; /Fermilab /CERN; Gilardoni, S.; Jowett, J.M.; /CERN

    2009-08-01

    Electromagnetic interactions between colliding heavy ions at the Large Hadron Collider (LHC) at CERN will give rise to localized beam losses that may quench superconducting magnets, apart from contributing significantly to the luminosity decay. To quantify their impact on the operation of the collider, we have used a three-step simulation approach, which consists of optical tracking, a Monte-Carlo shower simulation and a thermal network model of the heat flow inside a magnet. We present simulation results for the case of {sup 208}Pb{sup 82+} ion operation in the LHC, with focus on the alice interaction region, and show that the expected heat load during nominal {sup 208}Pb{sup 82+} operation is 40% above the quench level. This limits the maximum achievable luminosity. Furthermore, we discuss methods of monitoring the losses and possible ways to alleviate their effect.

  10. New method of optimizing writing parameters in electron beam lithography systems for throughput improvement considering patterning fidelity constraints

    Science.gov (United States)

    Ng, Hoi-Tou; Shen, Yu-Tian; Chen, Sheng-Yung; Liu, Chun-Hung; Ng, Philip C. W.; Tsai, Kuen-Yu

    2012-07-01

    Low-energy electron beam lithography is one of the promising next-generation lithography technology solutions for the 21-nm half-pitch node and beyond because of fewer proximity effects, higher resist sensitivity, and less substrate damage compared with high-energy electron beam lithography. To achieve high-throughput manufacturing, low-energy electron beam lithography systems with writing parameters of larger beam size, larger grid size, and lower dosage are preferred. However, electron shot noise can significantly increase critical dimension deviation and line edge roughness. Its influence on patterning prediction accuracy becomes nonnegligible. To effectively maximize throughput while meeting patterning fidelity requirements according to the International Technology Roadmap for Semiconductors, a new method is proposed in this work that utilizes a new patterning prediction algorithm to rigorously characterize the patterning variability caused by the shot noise and a mathematical optimization algorithm to determine optimal writing parameters. The new patterning prediction algorithm can achieve a proper trade-off between computational effort and patterning prediction accuracy. Effectiveness of the new method is demonstrated on a static random-access memory circuit. The corresponding electrical performance is analyzed by using a gate-slicing technique and publicly available transistor models. Numerical results show that a significant improvement in the static noise margin can be achieved.

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

    Science.gov (United States)

    Song, Sung-Jin; Kim, Chang-Hwan

    2002-05-01

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

  12. Soft X-Ray Magnetic Imaging of Focused Ion Beam Lithographically Patterned Fe Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Cook, Paul J.; Shen, Tichan H.; Grundy, PhilJ.; Im, Mi Young; Fischer, Peter; Morton, Simon A.; Kilcoyne, Arthur D.L.

    2008-11-09

    We illustrate the potential of modifying the magnetic behavior and structural properties of ferromagnetic thin films using focused ion beam 'direct-write' lithography. Patterns inspired by the split-ring resonators often used as components in meta-materials were defined upon 15 nm Fe films using a 30 keV Ga{sup +} focused ion beam at a dose of 2 x 10{sup 16} ions cm{sup -2}. Structural, chemical and magnetic changes to the Fe were studied using transmission soft X-ray microscopy at the ALS, Berkeley CA. X-ray absorption spectra showed a 23% reduction in the thickness of the film in the Ga irradiated areas, but no change to the chemical environment of Fe was evident. X-ray images of the magnetic reversal process show domain wall pinning around the implanted areas, resulting in an overall increase in the coercivity of the film. Transmission electron microscopy showed significant grain growth in the implanted regions.

  13. Development and characterization of micro-pattern gas detectors for intense beams of hadrons

    Energy Technology Data Exchange (ETDEWEB)

    Vandenbroucke, Maxence

    2012-07-02

    This thesis work is dedicated to the design, development and characterization of Micro-Pattern Gas Detectors. The performances of a Time Projection Chamber (TPC) equipped with a triple Gas Electron Multiplier (GEM) amplification structure are reported. The intrinsic ion backflow suppression of GEM foils drastically reduces the space charge produced by wire readout in traditional TPC. The GEM solution allows the operation of a TPC at much higher event rate. The second part of this thesis describes the development of a 40 x 40 cm{sup 2} Micromegas detector with a highly segmented central area. A reduction of discharges compared to conventional Micromegas detectors is needed for stable operation in intense beams of hadrons. Spark reduction technologies have been successfully studied and results are presented.

  14. Polarized Uniform Linear Array System: Beam Radiation Pattern, Beamforming Diversity Order, and Channel Capacity

    Directory of Open Access Journals (Sweden)

    Xin Su

    2015-01-01

    Full Text Available There have been many studies regarding antenna polarization; however, there have been few publications on the analysis of the channel capacity for polarized antenna systems using the beamforming technique. According to Chung et al., the channel capacity is determined by the density of scatterers and the transmission power, which is obtained based on the assumption that scatterers are uniformly distributed on a 3D spherical scattering model. However, it contradicts the practical scenario, where scatterers may not be uniformly distributed under outdoor environment, and lacks the consideration of fading channel gain. In this study, we derive the channel capacity of polarized uniform linear array (PULA systems using the beamforming technique in a practical scattering environment. The results show that, for PULA systems, the channel capacity, which is boosted by beamforming diversity, can be determined using the channel gain, beam radiation pattern, and beamforming diversity order (BDO, where the BDO is dependent on the antenna characteristics and array configurations.

  15. Quantifying spatial habitat loss from hydrocarbon development through assessing habitat selection patterns of mule deer.

    Science.gov (United States)

    Northrup, Joseph M; Anderson, Charles R; Wittemyer, George

    2015-11-01

    Extraction of oil and natural gas (hydrocarbons) from shale is increasing rapidly in North America, with documented impacts to native species and ecosystems. With shale oil and gas resources on nearly every continent, this development is set to become a major driver of global land-use change. It is increasingly critical to quantify spatial habitat loss driven by this development to implement effective mitigation strategies and develop habitat offsets. Habitat selection is a fundamental ecological process, influencing both individual fitness and population-level distribution on the landscape. Examinations of habitat selection provide a natural means for understanding spatial impacts. We examined the impact of natural gas development on habitat selection patterns of mule deer on their winter range in Colorado. We fit resource selection functions in a Bayesian hierarchical framework, with habitat availability defined using a movement-based modeling approach. Energy development drove considerable alterations to deer habitat selection patterns, with the most substantial impacts manifested as avoidance of well pads with active drilling to a distance of at least 800 m. Deer displayed more nuanced responses to other infrastructure, avoiding pads with active production and roads to a greater degree during the day than night. In aggregate, these responses equate to alteration of behavior by human development in over 50% of the critical winter range in our study area during the day and over 25% at night. Compared to other regions, the topographic and vegetative diversity in the study area appear to provide refugia that allow deer to behaviorally mediate some of the impacts of development. This study, and the methods we employed, provides a template for quantifying spatial take by industrial activities in natural areas and the results offer guidance for policy makers, mangers, and industry when attempting to mitigate habitat loss due to energy development.

  16. In situ radiation test of silicon and diamond detectors operating in superfluid helium and developed for beam loss monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Kurfürst, C.; Dehning, B.; Sapinski, M.; Bartosik, M.R.; Eisel, T.; Fabjan, C.; Rementeria, C.A. [CERN, Geneva (Switzerland); Griesmayer, E. [CIVIDEC Instrumentation, GmbH, Vienna (Austria); Eremin, V. [Ioffe Institute, St. Petersburg (Russian Federation); Verbitskaya, E., E-mail: elena.verbitskaya@cern.ch [Ioffe Institute, St. Petersburg (Russian Federation); Zabrodskii, A.; Fadeeva, N.; Tuboltsev, Y.; Eremin, I. [Ioffe Institute, St. Petersburg (Russian Federation); Egorov, N. [Research Institute of Material Science and Technology, Zelenograd, Moscow (Russian Federation); Härkönen, J.; Luukka, P.; Tuominen, E. [Helsinki Institute of Physics, Helsinki (Finland)

    2015-05-11

    As a result of the foreseen increase in the luminosity of the Large Hadron Collider, the discrimination between the collision products and possible magnet quench-provoking beam losses of the primary proton beams is becoming more critical for safe accelerator operation. We report the results of ongoing research efforts targeting the upgrading of the monitoring system by exploiting Beam Loss Monitor detectors based on semiconductors located as close as possible to the superconducting coils of the triplet magnets. In practice, this means that the detectors will have to be immersed in superfluid helium inside the cold mass and operate at 1.9 K. Additionally, the monitoring system is expected to survive 20 years of LHC operation, resulting in an estimated radiation fluence of 1×10{sup 16} proton/cm{sup 2}, which corresponds to a dose of about 2 MGy. In this study, we monitored the signal degradation during the in situ irradiation when silicon and single-crystal diamond detectors were situated in the liquid/superfluid helium and the dependences of the collected charge on fluence and bias voltage were obtained. It is shown that diamond and silicon detectors can operate at 1.9 K after 1×10{sup 16} p/cm{sup 2} irradiation required for application as BLMs, while the rate of the signal degradation was larger in silicon detectors than in the diamond ones. For Si detectors this rate was controlled mainly by the operational mode, being larger at forward bias voltage. - Highlights: • Silicon and diamond detectors are proposed for beam loss monitoring at LHC. • The first in situ radiation test of Si and diamond detectors at 1.9 K is described. • Both diamond and silicon detectors survived after 1×10{sup 16} p/cm{sup 2} irradiation at 1.9 K. • The rate of Si detectors degradation depends on bias polarity and is larger at V{sub forw}. • Sensitivity of Si detectors irradiated to 1×10{sup 16} p/cm{sup 2} is independent on resistivity.

  17. Patterning of Spiral Structure on Optical Fiber by Focused-Ion-Beam Etching

    Science.gov (United States)

    Mekaru, Harutaka; Yano, Takayuki

    2012-06-01

    We produce patterns on minute and curved surfaces of optical fibers, and develop a processing technology for fabricating sensors, antennas, electrical circuits, and other devices on such patterned surfaces by metallization. A three-dimensional processing technology can be used to fabricate a spiral coil on the surface of cylindrical quartz materials, and then the microcoils can also be applied to capillaries of micro-fluid devices, as well as to receiver coils connected to a catheter and an endoscope of nuclear magnetic resonance imaging (MRI) systems used in imaging blood vessels. To create a spiral line pattern with a small linewidth on a full-circumference surface of an optical fiber, focused-ion-beam (FIB) etching was employed. Here, a simple rotation stage comprising a dc motor and an LR3 battery was built. However, during the development of a prototype rotation stage before finalizing a large-scale remodelling of our FIB etching system, a technical problem was encountered where a spiral line could not be processed without running into breaks and notches in the features. It turned out that the problem was caused by axis blur resulting from an eccentric spinning (or wobbling) of the axis of the fiber caused by its unrestrained free end. The problem was solved by installing a rotation guide and an axis suppression device onto the rotation stage. Using this improved rotation stage. we succeeded in the seamless patterning of 1-µm-wide features on the full-circumference surface of a 250-µm-diameter quartz optical fiber (QOF) by FIB etching.

  18. Beam Losses in the Extraction Line of a TeV E+ E- Linear Collider With a 20-Mrad Crossing Angle

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, A.; /Uppsala U.; Nosochkov, Y.; /SLAC

    2006-03-29

    In this paper, we perform a detailed study of the power losses along the postcollision extraction line of a TeV e+e- collider with a crossing angle of 20 mrad between the beams at the interaction point. Five cases are considered here: four luminosity configurations for ILC and one for CLIC. For all of them, the strong beam-beam effects at the interaction point lead to an emittance growth for the outgoing beams, as well as to the production of beamstrahlung photons and e+e- pairs. The power losses along the 20 mrad extraction line, which are due to energy deposition by a fraction of the disrupted beam, of the beamstrahlung photons and of the e+e- coherent pairs, were estimated in the case of ideal collisions, as well as with a vertical position or angular o set at the interaction point.

  19. Evolution of beam losses after a power cut of the SR7 AC supply

    CERN Document Server

    GOMEZ ALONSO, A

    2009-01-01

    Magnet failures in the LHC could lead to equipment damage if the energy stored in the accelerator was not discharged properly. The Machine Protection Systems (MPS) ensure this proper discharge and knowledge about the evolution of losses in case of failure is needed to evaluate the adequacy of the protection. A power cut of the AC supply in SR7 would lead to a simultaneous current decay in three normal conducting circuits. The evolution of the losses after such failure is slow, with a loss time constant of more than 100 ms both at 450 GeV and 7 TeV, and in both cases the damage level is not reached before 45 ms. This leaves sufficient time for the MPS to ensure redundant protection. A similar scenario would be expected for a power cut at SR3.

  20. Loss of NAC1 expression is associated with defective bony patterning in the murine vertebral axis.

    Science.gov (United States)

    Yap, Kai Lee; Sysa-Shah, Polina; Bolon, Brad; Wu, Ren-Chin; Gao, Min; Herlinger, Alice L; Wang, Fengying; Faiola, Francesco; Huso, David; Gabrielson, Kathleen; Wang, Tian-Li; Wang, Jianlong; Shih, Ie-Ming

    2013-01-01

    NAC1 encoded by NACC1 is a member of the BTB/POZ family of proteins and participates in several pathobiological processes. However, its function during tissue development has not been elucidated. In this study, we compared homozygous null mutant Nacc1(-/-) and wild type Nacc1(+/+) mice to determine the consequences of diminished NAC1 expression. The most remarkable change in Nacc1(-/-) mice was a vertebral patterning defect in which most knockout animals exhibited a morphological transformation of the sixth lumbar vertebra (L6) into a sacral identity; thus, the total number of pre-sacral vertebrae was decreased by one (to 25) in Nacc1(-/-) mice. Heterozygous Nacc1(+/-) mice had an increased tendency to adopt an intermediate phenotype in which L6 underwent partial sacralization. Nacc1(-/-) mice also exhibited non-closure of the dorsal aspects of thoracic vertebrae T10-T12. Chondrocytes from Nacc1(+/+) mice expressed abundant NAC1 while Nacc1(-/-) chondrocytes had undetectable levels. Loss of NAC1 in Nacc1(-/-) mice was associated with significantly reduced chondrocyte migratory potential as well as decreased expression of matrilin-3 and matrilin-4, two cartilage-associated extracellular matrix proteins with roles in the development and homeostasis of cartilage and bone. These data suggest that NAC1 participates in the motility and differentiation of developing chondrocytes and cartilaginous tissues, and its expression is necessary to maintain normal axial patterning of murine skeleton.

  1. Loss of NAC1 expression is associated with defective bony patterning in the murine vertebral axis.

    Directory of Open Access Journals (Sweden)

    Kai Lee Yap

    Full Text Available NAC1 encoded by NACC1 is a member of the BTB/POZ family of proteins and participates in several pathobiological processes. However, its function during tissue development has not been elucidated. In this study, we compared homozygous null mutant Nacc1(-/- and wild type Nacc1(+/+ mice to determine the consequences of diminished NAC1 expression. The most remarkable change in Nacc1(-/- mice was a vertebral patterning defect in which most knockout animals exhibited a morphological transformation of the sixth lumbar vertebra (L6 into a sacral identity; thus, the total number of pre-sacral vertebrae was decreased by one (to 25 in Nacc1(-/- mice. Heterozygous Nacc1(+/- mice had an increased tendency to adopt an intermediate phenotype in which L6 underwent partial sacralization. Nacc1(-/- mice also exhibited non-closure of the dorsal aspects of thoracic vertebrae T10-T12. Chondrocytes from Nacc1(+/+ mice expressed abundant NAC1 while Nacc1(-/- chondrocytes had undetectable levels. Loss of NAC1 in Nacc1(-/- mice was associated with significantly reduced chondrocyte migratory potential as well as decreased expression of matrilin-3 and matrilin-4, two cartilage-associated extracellular matrix proteins with roles in the development and homeostasis of cartilage and bone. These data suggest that NAC1 participates in the motility and differentiation of developing chondrocytes and cartilaginous tissues, and its expression is necessary to maintain normal axial patterning of murine skeleton.

  2. A Bench Measurement of the Energy Loss of a Stored Beam to a Cavity

    Energy Technology Data Exchange (ETDEWEB)

    Sands, M; Rees, J.; /SLAC

    2016-12-19

    A rather simple electronic bench experiment is proposed for obtaining a measure of the impulse energy loss of a stored particle bunch to an rf cavity or other vacuum-chamber structure--the so-called "cavity radiation". The proposed method is analyzed in some detail.

  3. Nanoscale pattern formation at surfaces under ion-beam sputtering: A perspective from continuum models

    Energy Technology Data Exchange (ETDEWEB)

    Cuerno, Rodolfo, E-mail: cuerno@math.uc3m.e [Departamento de Matematicas and Grupo Interdisciplinar de Sistemas Complejos (GISC), Universidad Carlos III de Madrid, Avenida de la Universidad 30, E-28911 Leganes, Madrid (Spain); Castro, Mario [GISC and Grupo de Dinamica No Lineal (DNL), Escuela Tecnica Superior de Ingenieria (ICAI), Universidad Pontificia Comillas, E-28015 Madrid (Spain); Munoz-Garcia, Javier [Systems Biology Ireland and GISC, University College Dublin, Belfield, Dublin 4 (Ireland); Gago, Raul; Vazquez, Luis [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, E-28049 Madrid (Spain)

    2011-05-01

    Although reports on surface nanostructuring of solid targets by low to medium energy ion irradiation date back to the 1960s, only with the advent of high resolution tools for surface/interface characterization has the high potential of this procedure been recognized as a method for efficient production of surface patterns. Such morphologies are made up of periodic arrangements of nanometric sized features, like ripples and dots, with interest for technological applications due to their electronic, magnetic, and optical properties. Thus, roughly for the last ten years large efforts have been directed towards harnessing this nanofabrication technique. However, and particularly in view of recent experimental developments, we can say that the basic mechanisms controlling these pattern formation processes remain poorly understood. The lack of nanostructuring at low angles of incidence on some pure monoelemental targets, the role of impurities in the surface dynamics and other recent observations are challenging the classic view on the phenomenon as the mere interplay between the curvature dependence of the sputtering yield and surface diffusion. We review the main attempts at a theoretical (continuum) description of these systems, with emphasis on recent developments. Strong hints already exist that the nature of the morphological instability has to be rethought as originating in the material flow that is induced by the ion beam.

  4. Nanohole and dot patterning processes on quartz substrate by R-θ electron beam lithography and nanoimprinting

    Science.gov (United States)

    Watanabe, Tsuyoshi; Taniguchi, Kazutake; Suzuki, Kouta; Iyama, Hiromasa; Kishimoto, Shuji; Sato, Takashi; Kobayashi, Hideo

    2016-06-01

    Fine hole and dot patterns with bit pitches (bp’s) of less than 40 nm were fabricated in the circular band area of a quartz substrate by R-θ electron beam lithography (EBL), reactive ion etching (RIE), and nanoimprinting. These patterning processes were studied to obtain minimum pitch sizes of hole and dot patterns without pattern collapse. The patterning on the circular band was aimed to apply these patterning processes to future high-density bit-patterned media (BPM) for hard disk drive (HDD) and permanent memory for the long life archiving of digital data. In hole patterning, a minimum-22-nm-bp and 8.2-nm-diameter pattern (1.3 Tbit/in.2) was obtained on a quartz substrate by optimizing the R-θ EBL and RIE processes. Dot patterns were replicated on another quartz substrate by nanoimprinting using a hole-patterned quartz substrate as a master mold followed by RIE. In dot patterning, a minimum-30-nm-bp and 18.5-nm-diameter pattern (0.7 Tbit/in.2) was obtained by introducing new descum conditions. It was observed that the minimum bp of successful patterning increased as the fabrication process proceeded, i.e., from 20 nm bp in the first EBL process to 30 nm bp in the last quartz dot patterning process. From the measured diameters of the patterns, it was revealed that pattern collapse was apt to occur when the value of average diameter plus 3 sigma of diameter was close to the bp. It was suggested that multiple fabrication processes caused the degradation of pattern quality; therefore, hole patterning is more suitable than dot patterning for future applications owing to the lower quality degradation by its simple fabrication process.

  5. Numerical study for beam loss occurring for wide-ranging transverse injection painting and its mitigation scenario in the J-PARC 3-GeV RCS

    Science.gov (United States)

    Hotchi, Hideaki; Tani, Norio; Watanabe, Yasuhiro

    2015-04-01

    In the J-PARC 3-GeV Rapid Cycling Synchrotron (RCS), transverse injection painting is utilized to manipulate the transverse beam profile according to the requirements from the downstream facilities as well as to mitigate the space-charge induced beam loss in RCS. Therefore, a flexible control is required for the transverse painting area. But now the available range of transverse painting is limited to small area due to beta function beating caused by the edge focus of injection bump magnets which operate during the beam injection period. This beta function beating additionally excites various random betatron resonances through a distortion of the lattice super-periodicity, causing a shrinkage of the dynamic aperture during the injection period. This decrease of the dynamic aperture leads to extra beam loss at present when applying large transverse painting. For beta function beating caused by the edge focus, we proposed a correction scheme with additional pulse-type quadrupole correctors. In this paper, we will discuss the feasibility and effectiveness of this correction scheme for expanding the transverse injection painting area with no extra beam loss, while considering the beam loss and its mitigation mechanisms, based on numerical simulations.

  6. Patterns and Implications of Gene Gain and Loss in the Evolution of Prochlorococcus

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, Alla; Kettler, Gregory C.; Martiny, Adam C.; Huang, Katherine; Zucker, Jeremy; Coleman, Maureen L.; Rodrigue, Sebastien; Chen, Feng; Lapidus, Alla; Ferriera, Steven; Johnson, Justin; Steglich, Claudia; Church, George M.; Richardson, Paul; Chisholm, Sallie W.

    2007-07-30

    Prochlorococcus is a marine cyanobacterium that numerically dominates the mid-latitude oceans and is the smallest known oxygenic phototroph. Numerous isolatesfrom diverse areas of the world's oceans have been studied and shown to be physiologically and genetically distinct. All isolates described thus far can be assigned to either a tightly clustered high-light (HL)-adapted clade, or a more divergent low-light (LL)-adapted group. The 16S rRNA sequences of the entire Prochlorococcus group differ by at most 3percent, and the four initially published genomes revealed patterns of genetic differentiation that help explain physiological differences among the isolates. Here we describe the genomes of eight newly sequenced isolates and combine them with the first four genomes for a comprehensive analysis of the core (shared by all isolates) and flexible genes of the Prochlorococcus group, and the patterns of loss and gain of the flexible genes over the course of evolution. There are 1,273 genes that represent the core shared by all 12 genomes. They are apparently sufficient, according to metabolic reconstruction, to encode a functional cell. We describe a phylogeny for all 12 isolates by subjecting their complete proteomes to three different phylogenetic analyses. For each non-core gene, we used a maximum parsimony method to estimate which ancestor likely first acquired or lost each gene. Many of the genetic differences among isolates, especially for genes involved in outer membrane synthesis and nutrient transport, are found within the same clade. Nevertheless, we identified some genes defining HL and LL ecotypes, and clades within these broad ecotypes, helping to demonstrate the basis of HL and LL adaptations in Prochlorococcus. Furthermore, our estimates of gene gain events allow us to identify highly variable genomic islands that are not apparent through simple pairwise comparisons. These results emphasize the functional roles, especially those connected to outer

  7. Patterns and implications of gene gain and loss in the evolution of Prochlorococcus.

    Directory of Open Access Journals (Sweden)

    Gregory C Kettler

    2007-12-01

    Full Text Available Prochlorococcus is a marine cyanobacterium that numerically dominates the mid-latitude oceans and is the smallest known oxygenic phototroph. Numerous isolates from diverse areas of the world's oceans have been studied and shown to be physiologically and genetically distinct. All isolates described thus far can be assigned to either a tightly clustered high-light (HL-adapted clade, or a more divergent low-light (LL-adapted group. The 16S rRNA sequences of the entire Prochlorococcus group differ by at most 3%, and the four initially published genomes revealed patterns of genetic differentiation that help explain physiological differences among the isolates. Here we describe the genomes of eight newly sequenced isolates and combine them with the first four genomes for a comprehensive analysis of the core (shared by all isolates and flexible genes of the Prochlorococcus group, and the patterns of loss and gain of the flexible genes over the course of evolution. There are 1,273 genes that represent the core shared by all 12 genomes. They are apparently sufficient, according to metabolic reconstruction, to encode a functional cell. We describe a phylogeny for all 12 isolates by subjecting their complete proteomes to three different phylogenetic analyses. For each non-core gene, we used a maximum parsimony method to estimate which ancestor likely first acquired or lost each gene. Many of the genetic differences among isolates, especially for genes involved in outer membrane synthesis and nutrient transport, are found within the same clade. Nevertheless, we identified some genes defining HL and LL ecotypes, and clades within these broad ecotypes, helping to demonstrate the basis of HL and LL adaptations in Prochlorococcus. Furthermore, our estimates of gene gain events allow us to identify highly variable genomic islands that are not apparent through simple pairwise comparisons. These results emphasize the functional roles, especially those connected to

  8. Emission and propagation of Saturn kilometric radiation: Magnetoionic modes, beaming pattern, and polarization state

    Science.gov (United States)

    Lamy, L.; Cecconi, B.; Zarka, P.; Canu, P.; Schippers, P.; Kurth, W. S.; Mutel, R. L.; Gurnett, D. A.; Menietti, D.; Louarn, P.

    2011-04-01

    The Cassini mission crossed the source region of the Saturn kilometric radiation (SKR) on 17 October 2008. On this occasion, the Radio and Plasma Wave Science (RPWS) experiment detected both local and distant radio sources, while plasma parameters were measured in situ by the magnetometer and the Cassini Plasma Spectrometer. A goniopolarimetric inversion was applied to RPWS three-antenna electric measurements to determine the wave vector k and the complete state of polarization of detected waves. We identify broadband extraordinary (X) mode as well as narrowband ordinary (O) mode SKR at low frequencies. Within the source region, SKR is emitted just above the X mode cutoff frequency in a hot plasma, with a typical electron-to-wave energy conversion efficiency of ˜1% (2% peak). The knowledge of the k vector is then used to derive the locus of SKR sources in the kronian magnetosphere, which shows X and O components emanating from the same regions. We also compute the associated beaming angle at the source θ‧ = (k, -B) either from (1) in situ measurements or a model of the magnetic field vector (for local to distant sources) or (2) polarization measurements (for local sources). Obtained results, similar for both modes, suggest quasi-perpendicular emission for local sources, whereas the beaming pattern of distant sources appears as a hollow cone with a frequency-dependent constant aperture angle: θ‧ = 75° ± 15° below 300 kHz, decreasing at higher frequencies to reach θ‧ (1000 kHz) = 50° ± 25°. Finally, we investigate quantitatively the SKR polarization state, observed to be strongly elliptical at the source, and quasi-purely circular for sources located beyond approximately two kronian radii. We show that conditions of weak mode coupling are achieved along the raypath, under which the magnetoionic theory satisfactorily describes the evolution of the observed polarization. These results are analyzed comparatively with the auroral kilometric radiation at

  9. Effects of focused ion beam milling on electron backscatter diffraction patterns in strontium titanate and stabilized zirconia

    DEFF Research Database (Denmark)

    Saowadee, Nath; Agersted, Karsten; Bowen, Jacob R.

    2012-01-01

    This study investigates the effect of focused ion beam (FIB) current and accelerating voltage on electron backscatter diffraction pattern quality of yttria‐stabilized zirconia (YSZ) and Nb‐doped strontium titanate (STN) to optimize data quality and acquisition time for 3D‐EBSD experiments by FIB...

  10. Patterns of hybrid loss of imprinting reveal tissue- and cluster-specific regulation.

    Directory of Open Access Journals (Sweden)

    Christopher D Wiley

    Full Text Available BACKGROUND: Crosses between natural populations of two species of deer mice, Peromyscus maniculatus (BW, and P. polionotus (PO, produce parent-of-origin effects on growth and development. BW females mated to PO males (bwxpo produce growth-retarded but otherwise healthy offspring. In contrast, PO females mated to BW males (POxBW produce overgrown and severely defective offspring. The hybrid phenotypes are pronounced in the placenta and include POxBW conceptuses which lack embryonic structures. Evidence to date links variation in control of genomic imprinting with the hybrid defects, particularly in the POxBW offspring. Establishment of genomic imprinting is typically mediated by gametic DNA methylation at sites known as gDMRs. However, imprinted gene clusters vary in their regulation by gDMR sequences. METHODOLOGY/PRINCIPAL FINDINGS: Here we further assess imprinted gene expression and DNA methylation at different cluster types in order to discern patterns. These data reveal POxBW misexpression at the Kcnq1ot1 and Peg3 clusters, both of which lose ICR methylation in placental tissues. In contrast, some embryonic transcripts (Peg10, Kcnq1ot1 reactivated the silenced allele with little or no loss of DNA methylation. Hybrid brains also display different patterns of imprinting perturbations. Several cluster pairs thought to use analogous regulatory mechanisms are differentially affected in the hybrids. CONCLUSIONS/SIGNIFICANCE: These data reinforce the hypothesis that placental and somatic gene regulation differs significantly, as does that between imprinted gene clusters and between species. That such epigenetic regulatory variation exists in recently diverged species suggests a role in reproductive isolation, and that this variation is likely to be adaptive.

  11. Foraging Activity Pattern Is Shaped by Water Loss Rates in a Diurnal Desert Rodent.

    Science.gov (United States)

    Levy, Ofir; Dayan, Tamar; Porter, Warren P; Kronfeld-Schor, Noga

    2016-08-01

    Although animals fine-tune their activity to avoid excess heat, we still lack a mechanistic understanding of such behaviors. As the global climate changes, such understanding is particularly important for projecting shifts in the activity patterns of populations and communities. We studied how foraging decisions vary with biotic and abiotic pressures. By tracking the foraging behavior of diurnal desert spiny mice in their natural habitat and estimating the energy and water costs and benefits of foraging, we asked how risk management and thermoregulatory requirements affect foraging decisions. We found that water requirements had the strongest effect on the observed foraging decisions. In their arid environment, mice often lose water while foraging for seeds and cease foraging even at high energetic returns when water loss is high. Mice also foraged more often when energy expenditure was high and for longer times under high seed densities and low predation risks. Gaining insight into both energy and water balance will be crucial to understanding the forces exerted by changing climatic conditions on animal energetics, behavior, and ecology.

  12. Direct patterning of vortex generators on a fiber tip using a focused ion beam.

    Science.gov (United States)

    Vayalamkuzhi, Pramitha; Bhattacharya, Shanti; Eigenthaler, Ulrike; Keskinbora, Kahraman; Samlan, C T; Hirscher, Michael; Spatz, Joachim P; Viswanathan, Nirmal K

    2016-05-15

    The realization of spiral phase optical elements on the cleaved end of an optical fiber by focused ion beam milling is presented. A focused Ga+ ion beam with an acceleration voltage of 30 keV is used to etch continuous spiral phase plates and fork gratings directly on the tip of the fiber. The phase characteristics of the output beam generated by the fabricated structures measured via an interference experiment confirmed the presence of phase singularity in the output beam. The devices are expected to be promising candidates for all-fiber beam shaping and optical trapping applications.

  13. Formation of Ga droplets on patterned GaAs (100) by molecular beam epitaxy.

    Science.gov (United States)

    Li, Ming-Yu; Hirono, Yusuke; Koukourinkova, Sabina D; Sui, Mao; Song, Sangmin; Kim, Eun-Soo; Lee, Jihoon; Salamo, Gregory J

    2012-10-03

    In this paper, the formation of Ga droplets on photo-lithographically patterned GaAs (100) and the control of the size and density of Ga droplets by droplet epitaxy using molecular beam epitaxy are demonstrated. In extension of our previous result from the journal Physical Status Solidi A, volume 209 in 2012, the sharp contrast of the size and density of Ga droplets is clearly observed by high-resolution scanning electron microscope, atomic force microscope, and energy dispersive X-ray spectrometry. Also, additional monolayer (ML) coverage is added to strength the result. The density of droplets is an order of magnitude higher on the trench area (etched area), while the size of droplets is much larger on the strip top area (un-etched area). A systematic variation of ML coverage results in an establishment of the control of size and density of Ga droplets. The cross-sectional line profile analysis and root mean square roughness analysis show that the trench area (etched area) is approximately six times rougher. The atomic surface roughness is suggested to be the main cause of the sharp contrast of the size and density of Ga droplets and is discussed in terms of surface diffusion.

  14. The Hydrogen Epoch of Reionization Array Dish I: Beam Pattern Measurements and Science Implications

    CERN Document Server

    Neben, Abraham R; Hewitt, Jacqueline N; DeBoer, David R; Parsons, Aaron R; Aguirre, James E; Ali, Zaki S; Cheng, Carina; Ewall-Wice, Aaron; Patra, Nipanjana; Thyagarajan, Nithyanandan; Bowman, Judd; Dickenson, Roger; Dillon, Joshua S; Doolittle, Phillip; Egan, Dennis; Hedrick, Mike; Jacobs, Daniel C; Kohn, Saul A; Klima, Patricia J; Moodley, Kavilan; Saliwanchik, Benjamin R B; Schaffner, Patrick; Shelton, John; Taylor, H A; Taylor, Rusty; Tegmark, Max; Wirt, Butch; Zheng, Haoxuan

    2016-01-01

    The Hydrogen Epoch of Reionization Array (HERA) is a radio interferometer aiming to detect the power spectrum of 21cm fluctuations from neutral hydrogen from the Epoch of Reionization (EOR). Drawing on lessons from the Murchison Widefield Array (MWA) and the Precision Array for Probing the Epoch of Reionization (PAPER), HERA is a hexagonal array of large (14m diameter) dishes with suspended dipole feeds. Not only does the dish determine overall sensitivity, it affects the observed frequency structure of foregrounds in the interferometer. This is the first of a series of four papers characterizing the frequency and angular response of the dish with simulations and measurements. We focus in this paper on the angular response (i.e., power pattern), which sets the relative weighting between sky regions of high and low delay, and thus, apparent source frequency structure. We measure the angular response at 137MHz using the ORBCOMM beam mapping system of Neben et al. We measure a collecting area of 93m^2 in the opt...

  15. Influence of the beam-size or MD-effect on particle losses at B-factories PEP-II and KEKB

    CERN Document Server

    Kotkin, G L

    2004-01-01

    For the $e^+ e^- \\to e^+ e^- \\gamma$ process at colliding beams, macroscopically large impact parameters give an essential contribution to the standard cross section. These impact parameters may be much larger than the transverse sizes of the colliding bunches. It means that the standard calculations have to be essentially modify. In the present paper such a beam-size or MD-effect is calculated for bremsstrahlung at B-factories PEP-II and KEKB using the list of nominal parameters from Review of Particle Physics (2002). We find out that this effect reduces beam losses due to bremsstrahlung by about 20%.

  16. A phased array antenna with a broadly steerable beam based on a low-loss metasurface lens

    Science.gov (United States)

    Liu, Yahong; Jin, Xueyu; Zhou, Xin; Luo, Yang; Song, Kun; Huang, Lvhongzi; Zhao, Xiaopeng

    2016-10-01

    A new concept for a gradient phase discontinuity metasurface lens integrated with a phased array antenna possessing a broadly steerable beam is presented in this paper. The metasurface lens is composed of a metallic H-shaped pattern and the metallic square split ring can achieve complete 360° transmission phase coverage at 30° phase intervals. The metasurface can refract an incident plane wave to an angle at will by varying the lattice constant. We demonstrate that the beam steering range of the phased array antenna is between 12° and 85° when the metasurface lens with a refracting electromagnetic wave is employed at 45°. Interestingly, the proposed array antenna has a much higher gain than a conventional phased array antenna at low elevation angles. It is expected that the proposed array antenna will have potential applications in wireless and satellite communications. Furthermore, the proposed array antenna is fabricated easily and is also low in cost due to its microstrip technology.

  17. Characterizing Optical Loss in Orientation Patterned III-V Materials using Laser Calorimetry

    Science.gov (United States)

    2014-03-27

    Spectrophotometer transmission measurement for GaAs and GaP samples...size of 518 microns on the sample. A THOR Labs beam profiler was used to find this beam size. Also a calibrated Newport Power Meter and detector...A. Figure 39 presents the transmission measurements for GaAs and GaP samples using a CARY spectrophotometer . 59 Table 4: Absorptance

  18. 女性型脱发及治疗进展%Female pattern hair loss and its therapy

    Institute of Scientific and Technical Information of China (English)

    吴琼; 姜祎群

    2012-01-01

    脱发是影响患者生活质量的一种病症,发生在女性的脱发越来越引起人们的关注,女性型脱发也称女性雄激素性脱发,可按照传统的Ludwig分类法及O1sen分类法分类,目前也有较新的BASP分类法作为参考,了解女性型脱发及临床分型将有助于其治疗.目前除延续传统治疗方法,如局部使用米诺地尔外,新型的治疗方法不断被尝试用于治疗这类患者,如抗雄激素治疗、局部使用腺苷、光疗、毛发移植等.%Alopecia is a kind of disease that affects patients' quality of life.Hair loss in women,with female pattern hair loss as the main reason,is increasingly attracting attention.Female pattern hair loss,also called female androgenic alopecia,can be classified according to the traditional Ludwig and Olsen classification,or the recently developed BASP classification.Getting to know the definition and clinical patterns of female pattern hair loss will be helpful to its therapy.Besides traditional therapy such as topical minoxidil,some new approaches have been introduced to the treatment of female pattern hair loss,including topical adenosine,phototherapy,hair transplantation,etc.

  19. Effects of the spatial frequency composition of the target pattern and the number of quantization levels in diffractive beam shaper design.

    Science.gov (United States)

    Hsu, Ku-Hui; Lin, Hoang Yan

    2012-06-01

    A mathematical model is derived, and numerical simulation is analyzed for laser beam shaping by using multilevel phase-only diffractive optical elements (DOEs). We used the simulated annealing algorithm to design the beam shapers. The result has an essential effect on the diffractive pattern quality caused by the spatial frequency composition of target patterns for the same incident gaussian beam size and target pattern area. The root mean square error between the diffractive and target patterns is smaller for the target patterns with lower spatial frequencies. Moreover, the effect of spatial frequency composition can be relaxed for the cases of larger incident gaussian beam size. In addition, finer quality control of a diffraction pattern can be obtained by increasing the number of quantization levels at the DOEs.

  20. Monte Carlo simulations to estimate the damage potential of electron beam and tests of beam loss detector based on quartz Cherenkov radiator read out by a silicon photomultiplier on CLIC Test Facility 3(CTF3)

    CERN Document Server

    Orfanelli, Styliani; Gazis, E

    The Compact Linear Collider (CLIC) study is a feasibility study aiming at the development of an electron/positron linear collider with a centre of mass energy in the multi-TeV energy range. Each Linac will have a length of 21 km, which means that very high accelerating gradients (>100 MV/m) are required. To achieve the high accelerating gradients, a novel two-beam acceleration scheme, in which RF power is transferred from a high-current, low-energy drive beam to the low-current, high energy main accelerating beam is designed. A Beam Loss Monitoring (BLM) system will be designed for CLIC to meet the requirements of the accelerator complex. Its main role as part of the machine protection scheme will be to detect potentially dangerous beam instabilities and prevent subsequent injection into the main beam or drive beam decelerators. The first part of this work describes the GEANT4 Monte Carlo simulations performed to estimate the damage potential of high energy electron beams impacting a copper target. The second...

  1. E-Beam Patterned Gold Nanodot Arrays on Optical Fiber Tips for Localized Surface Plasmon Resonance Biochemical Sensing

    Directory of Open Access Journals (Sweden)

    Yongbin Lin

    2010-10-01

    Full Text Available Electron beam lithography (EBL was used to directly pattern periodic gold nanodot arrays on optical fiber tips. Localized surface plasmon resonance of the E-beam patterned gold nanodot arrays on optical fiber tips was utilized for biochemical sensing. The advantage of the optical fiber based localized surface plasmon resonance (LSPR sensors is the convenience to work with and work in harsh environments. An optical fiber tip LSPR refractive index sensor of 196 nm per refractive index unit (RIU sensitivity has been demonstrated. The affinity sensing property of the fiber tip sensor was demonstrated using biotin/streptavidin as the receptor/analyte. The detection limit for streptavidin was determined to be 6 pM.

  2. Shaped Beam Pattern Synthesis of Antenna Arrays Using Composite Differential Evolution with Eigenvector-Based Crossover Operator

    Directory of Open Access Journals (Sweden)

    Sotirios K. Goudos

    2015-01-01

    Full Text Available This paper addresses the problem of designing shaped beam patterns with arbitrary arrays subject to constraints. The constraints could include the sidelobe level suppression in specified angular intervals, the mainlobe halfpower beamwidth, and the predefined number of elements. In this paper, we propose a new Differential Evolution algorithm, which combines Composite DE with an eigenvector-based crossover operator (CODE-EIG. This operator utilizes eigenvectors of covariance matrix of individual solutions, which makes the crossover rotationally invariant. We apply this novel design method to shaped beam pattern synthesis for linear and conformal arrays. We compare this algorithm with other popular algorithms and DE variants. The results show CODE-EIG outperforms the other DE algorithms in terms of statistical results and convergence speed.

  3. Memory resistive switching in CeO2-based film microstructures patterned by a focused ion beam

    DEFF Research Database (Denmark)

    Velichko, A.; Boriskov, P.; Grishin, A.

    2014-01-01

    Heteroepitaxial CeO2 (80 nm)/La0.5Sr0.5CoO3 (500 nm) film structure has been pulsed laser deposited on a sapphire substrate. The Ag/CeO2 microjunctions patterned by a focused ion beam on a La0.5Sr0.5CoO3 film exhibit reproducible reversible switching between a high resistance state (OFF...

  4. INVESTIGATION OF DYNAMIC PARAMETRS OF SPLIT SKEWED BRIDGE SPANS IN CASE OF LOSS OF CONTACT BETWEEN END BEAM AND ITS SUPPORT

    Directory of Open Access Journals (Sweden)

    V.S.Safronov

    2015-02-01

    Full Text Available Statement of the problem. In order to get a valid estimate of risks of fracture during the mainten-ance of simply supported skew slab-and-girder reinforced concrete spans of highway bridges the influence of the supporting skew on the natural frequencies spectrum and the corresponding ei-genmodes in case of changing the design model due to loss of contact between beams and support.Results. Possible loss of contact between one of the marginal beams and its support near the sharp angle during the maintenance of transport facility depending on its type and geometrical parameters is substantiated. Modal and frequency spectrum analysis of spans in case of loss of contact between one of the marginal beams and its support is performed.Conclusions. The analysis revealed possible loss of contact between marginal beams and support, which increases as the skew angle grows and the width and length of the span reduce. A signifi-cant influence of support separation on eigenmodes and frequency spectrum of spans is revealed.

  5. Effects of competitive prey capture on flight behavior and sonar beam pattern in paired big brown bats, Eptesicus fuscus.

    Science.gov (United States)

    Chiu, Chen; Reddy, Puduru Viswanadha; Xian, Wei; Krishnaprasad, Perinkulam S; Moss, Cynthia F

    2010-10-01

    Foraging and flight behavior of echolocating bats were quantitatively analyzed in this study. Paired big brown bats, Eptesicus fuscus, competed for a single food item in a large laboratory flight room. Their sonar beam patterns and flight paths were recorded by a microphone array and two high-speed cameras, respectively. Bats often remained in nearly classical pursuit (CP) states when one bat is following another bat. A follower can detect and anticipate the movement of the leader, while the leader has the advantage of gaining access to the prey first. Bats in the trailing position throughout the trial were more successful in accessing the prey. In this study, bats also used their sonar beam to monitor the conspecific's movement and to track the prey. Each bat tended to use its sonar beam to track the prey when it was closer to the worm than to another bat. The trailing bat often directed its sonar beam toward the leading bat in following flight. When two bats flew towards each other, they tended to direct their sonar beam axes away from each other, presumably to avoid signal jamming. This study provides a new perspective on how echolocating bats use their biosonar system to coordinate their flight with conspecifics in a group and how they compete for the same food source with conspecifics.

  6. Patterns of weight loss and supplement consumption of male wrestlers in Tehran

    Directory of Open Access Journals (Sweden)

    Kordi Ramin

    2011-02-01

    Full Text Available Abstract Background To evaluate the weight loss behavior of male wrestlers in Tehran Methods This study was a population-based cross sectional survey. Subjects were 436 wrestlers randomly selected from the wrestling clubs in Tehran employing cluster sample setting method. Subjects were interviewed based on a designed questionnaire. Body fat levels were measured based on skin fold measurements. Results Weight loss methods practiced by 62% of all subjects during the previous year employing rapid (≤7 days before the matches and gradual (>7 days before the matches weight reduction methods (73% and 34% of wrestlers who reduced their weight respectively. In addition, opinions on weight reduction, the methods of weight loss used, and the side effects of the weight loss practices as well as consumption of supplements among the subjects were reported in this study. The mean percentage of body fat of subjects was 15.9%. Conclusions Rapid weight loss for matches and the use of unsafe methods of weight reduction such as fasting, and fluid reduction methods as well as acute side effects of weight loss were prevalent among wrestlers in Tehran. Some preventive measures including education and new rules such as scheduling weigh-ins immediately prior to the competitions and mat-side weigh-in are needed to prevent these unhealthy practices. The weight loss behaviors of these wrestlers should be changed from using dehydration methods to using gradual methods of weight loss.

  7. Spatial patterns of extra-pair paternity: beyond paternity gains and losses.

    Science.gov (United States)

    Schlicht, Lotte; Valcu, Mihai; Kempenaers, Bart

    2015-03-01

    Most studies on extra-pair paternity (EPP) focus either on a specific male's extra-pair gains or his extra-pair losses. For an individual bird however, mate choice or mate availability may underlie strong spatial restrictions. Disregarding this spatial aspect may underestimate or mask effects of parameters influencing observed EPP patterns. Here, we propose a spatially explicit model for investigating the probability of having extra-pair offspring (EPO) within local networks of breeding pairs. The data set includes all realized and unrealized potential extra-pair matings. This method is biologically meaningful because it allows (a) considering both members of an extra-pair mating and their social mates, and (b) direct modelling of the spatial context in which extra-pair behaviour occurs. The method has the advantage that it can provide inference about the relative contribution of spatial and non-spatial parameters, and about the relative importance of male and female neighbourhoods. We apply this method to parentage data from 1025 broods collected over 12 breeding seasons in two independent study populations of blue tits (Cyanistes caeruleus). We investigate a set of predictions based on the EPP literature, namely that EPP depends on male age and body size, breeding density and breeding synchrony. In all analyses, we control for breeding distance, a parameter that is expected to influence EPP even under random mating. The results show that older and larger males were more likely to sire EPO, but both effects decreased with increasing breeding distance. Local breeding density but not synchrony predicted whether a particular male-female combination had EPO, at least in one of the study areas. Apart from breeding distance, male age had the strongest effect on EPP, followed by a measure of breeding density. The method thus allows a comprehensive assessment of the relative importance of different types of spatial and non-spatial parameters to explain variation in the

  8. Detailed ice loss pattern in the northern Antarctic Peninsula: widespread decline driven by ice front retreats

    Directory of Open Access Journals (Sweden)

    T. A. Scambos

    2014-06-01

    Full Text Available The northern Antarctic Peninsula (nAP, 3 a−1 and 24.9 ± 7.8 Gt a−1. This mass loss is compatible with recent gravimetric assessments, but it implies that almost all the gravimetry-inferred loss lies in the nAP sector. Mass loss is highest for eastern glaciers affected by major ice shelf collapses in 1995 and 2002, where twelve glaciers account for 60% of the total imbalance. However, losses at smaller rates occur throughout the nAP, and at high and low elevation, despite increased snow accumulation along the western coast and at high elevations. We interpret the widespread mass loss to be driven by decades of ice front retreats on both sides of the nAP, and by the propagation of kinematic waves triggered at the fronts into the interior.

  9. Measurement of Absolute Excitation Cross Sections in Highly-Charged Ions Using Electron Energy Loss and Merged Beams

    Science.gov (United States)

    Chutjian, A.; Smith, Steven J.; Lozano, J.

    2002-01-01

    There is increasing emphasis during this decade on understanding energy balance and phenomena observed in high electron temperature plasmas. The UV spectral return from FUSE, the X-ray spectral return from the HETG on Chandra and the LETGS 011 XMM-Newton are just beginning. Line emissions are almost entirely from highly-charged ions (HCIs) of C, N, 0, Ne, Mg, S, Si, Ca, and Fe. The Constellation-X mission will provide X-ray spectroscopy up to photon energies of 0.12 nm (10 keV) where primary line emitters will be HCIs. A variety of atomic parameters are required to model the stellar and solar plasma. These include cross sections for excitation, ionization, charge-exchange, X-ray emission, direct and indirect recombination, lifetimes and branching ratios, and dependences on l, m mixing by external E and B fields. In almost all cases the atomic quantities are calculated, and few comparisons to experiment have been carried out. Collision strengths and Einstein A-values are required to convert the observed spectral intensities to electron temperatures and densities in the stellar plasma. The JPL electron energy-loss and merged beam approach has been used to measure absolute collision strengths in a number of ions, with critical comparison made to the best available theories.

  10. Spatial pattern of mass loss processes across the Greenland Ice Sheet from the Little Ice Age to 2010

    DEFF Research Database (Denmark)

    Kjaer, K. H.; Korsgaard, N. J.; Kjeldsen, K. K.;

    The Greenland Ice Sheet loses mass through surface meltwater runoff and discharge from marine terminating outlet glaciers. The spatial variability and magnitude of these processes have been studied and described in detail for the past decades. Here, we combine the mass loss between the LIA to 2010...... (ICESat) from 2003-2009, NASA's Land, Vegetation, and Ice Sensor (LVIS) from 2010, and ASTER (Silcast AST14DMO) co-registered to ICESat, to estimate mass loss throughout the 20th and early 21st Century. The mass balance estimates of the GrIS since retreat from maximum LIA is combined with a SMB model...... correspond to those that experienced considerable thinning throughout the 20th century. Consequently, comparing the 20th century thinning pattern to that of the last decade, and assuming a similar warming pattern, we argue that the present sensitivity distribution will hold also for future ice sheet mass...

  11. Spontaneous decoration of Au nanoparticles on micro-patterned reduced graphene oxide shaped by focused laser beam

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Y. C.; Tok, E. S. [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Teoh, H. F. [Graduate School of Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456 (Singapore); Sow, C. H. [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Graduate School of Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456 (Singapore)

    2015-02-07

    We report a facile, two-step method for the micro-landscaping of Au nanoparticles(NPs) on reduced graphene oxide (rGO) film en route to micro-patterned Au(NPs)-rGO hybrid functional materials. This method employs a focused laser beam to first locally convert GO to rGO before immersing the micro-patterned GO-rGO film into HAuCl{sub 4} solution. The rGO micro-pattern, shaped by the focused laser beam, serves as nucleation sites for the reduction of Au ions. The reduction mechanism that governs the decoration of Au NPs on rGO films is akin to electroless deposition process. In this instance, surface charges that are formed during laser reduction of GO to rGO provide active nucleation sites for Au{sup 3+} ions to form Au NPs when HAuCl{sub 4} solution is introduced. The number density, the size, and size distribution of the Au NPs can thus be directly tuned and preferentially anchored onto the rGO micro-pattern by varying the incident laser power, the scanning speed of the laser, or the concentration of HAuCl{sub 4}. The resulting hybrid materials can be used as a substrate for Surface Enhanced Raman Spectroscopy (SERS). Using Rhodamine 6G as the test subject, we found an improvement of SERS enhancement over bare rGO of up to four times, depending on the size of the Au NPs.

  12. Initial benchmarking of a new electron-beam raster pattern generator for 130-100 nm maskmaking

    Science.gov (United States)

    Sauer, Charles A.; Abboud, Frank E.; Babin, Sergey V.; Chakarian, Varoujan; Ghanbari, Abe; Innes, Robert; Trost, David; Raymond, Frederick, III

    2000-07-01

    The decision by the Semiconductor Industry Association (SIA) to accelerate the continuing evolution to smaller linewidths is consistent with the commitment by Etec Systems, Inc. to rapidly develop new technologies for pattern generation systems with improved resolution, critical dimension (CD) uniformity, positional accuracy, and throughput. Current pattern generation designs are inadequate to meet the more advanced requirements for masks, particularly at or below the 100 nm node. Major changes to all pattern generation tools will be essential to meet future market requirements. An electron-beam (e-beam) system that is designed to meet the challenges for 130 - 100 nm device generation with extendibility to the 70-nm range will be discussed. This system has an architecture that includes a graybeam writing strategy, a new state system, and improved thermal management. Detailed changes include a pulse width modulated blanking system, per-pixel deflection, retrograde scanning multipass writing, and a column with a 50 kV accelerating voltage that supports a dose of up to 45 (mu) C/cm2 with minimal amounts of resist heating. This paper examines current issues, our approach to meeting International Technology Roadmap for Semiconductors (ITRS) requirements, and some preliminary results from a new pattern generator.

  13. Ab-initio primitive cell parameters from single convergent-beam electron diffraction patterns: a converse route to the identification of microcrystals with electrons.

    Science.gov (United States)

    Le Page, Y

    1992-04-01

    A new method for the ab initio derivation of Buerger-reduced primitive cell parameters from coordinate measurements of spots on single convergent-beam electron diffraction (CBED) patterns is described, which does not involve trial-and-error. The pattern can be taken along any zone axis, and misorientations of the crystallite by as much as a few degrees are taken into account without loss of accuracy. This derivation of cell parameters by least-squares analysis of the measurements has been automated in a program called NRCBED. Present accuracy is about 1% on lengths and 2 degrees on angles, but could be significantly improved by modelling projector lens aberrations, or by using a microscope without a projector lens. With present technology, it is possible to obtain a CBED pattern and a semi-quantitative energy-dispersive X-ray (EDX) analysis simultaneously from a single microcrystal a few hundred Angströms across. It becomes therefore possible to identify the material of the crystal on a single CBED pattern: a cell parameter database for known compounds is searched with the primitive cell parameters obtained in the above way, and with a mask describing the EDX results qualitatively. Feasibility is demonstrated on a crystallite of CeO2 500 Angströms across. With this new approach, trial-and-error should disappear from the solution of other long-standing problems: interpretation of X-ray powder patterns for new compounds in the presence of impurity lines, or in the case of multiple phases should become straight-forward.

  14. Beam-loss induced pressure rise of Large Hadron Collider collimator materials irradiated with 158 GeV/u $In^{49+}$ ions at the CERN Super Proton Synchrotron

    CERN Document Server

    Mahner, Edgar; Hansen, Jan; Page, Eric; Vincke, H

    2004-01-01

    During heavy ion operation, large pressure rises, up to a few orders of magnitude, were observed at CERN, GSI, and BNL. The dynamic pressure rises were triggered by lost beam ions that impacted onto the vacuum chamber walls and desorbed about 10/sup 4/ to 10/sup 7/ molecules per ion. The deterioration of the dynamic vacuum conditions can enhance charge-exchange beam losses and can lead to beam instabilities or even to beam abortion triggered by vacuum interlocks. Consequently, a dedicated measurement of heavy-ion induced molecular desorption in the GeV/u energy range is important for Large Hadron Collider (LHC) ion operation. In 2003, a desorption experiment was installed at the super proton synchrotron to measure the beam-loss induced pressure rise of potential LHC collimator materials. Samples of bare graphite, sputter coated (Cu, TiZrV) graphite, and 316 LN (low carbon with nitrogen) stainless steel were irradiated under grazing angle with 158 GeV/u indium ions. After a description of the new experimental ...

  15. Beam-Loss Induced Pressure Rise of LHC Collimator Materials Irradiated with 158 GeV/u $In^{49+}$ Ions at the CERN SPS

    CERN Document Server

    Mahner, Edgar; Hansen, Jan; Page, Eric; Vincke, Helmut H

    2004-01-01

    During heavy ion operation, large pressure rises, up to a few orders of magnitude, were observed at CERN, GSI, and BNL. The dynamic pressure rises were triggered by lost beam ions that impacted onto the vacuum chamber walls and desorbed about 1044 to 107 molecules per ion. The deterioration of the dynamic vacuum conditions can enhance charge-exchange beam losses and can lead to beam instabilities or even to beam abortion triggered by vacuum interlocks. Consequently, a dedicated measure-ment of heavy-ion induced molecular desorption in the GeV/u energy range is important for LHC ion operation. In 2003, a desorption experiment was installed at the SPS to measure the beam-loss induced pressure rise of potential LHC collimator materials. Samples of bare graphite, sputter coated (Cu, TiZrV) graphite, and 316 LN stainless steel, were irradiated under grazing angle with 158 GeV/u indium ions. After a description of the new experimental set-up, the results of the pressure rise measurements are presented, and the deri...

  16. Beam-loss induced pressure rise of Large Hadron Collider collimator materials irradiated with 158 GeV/u In49+ ions at the CERN Super Proton Synchrotron

    Science.gov (United States)

    Mahner, E.; Efthymiopoulos, I.; Hansen, J.; Page, E.; Vincke, H.

    2004-10-01

    During heavy ion operation, large pressure rises, up to a few orders of magnitude, were observed at CERN, GSI, and BNL. The dynamic pressure rises were triggered by lost beam ions that impacted onto the vacuum chamber walls and desorbed about 104 to 107 molecules per ion. The deterioration of the dynamic vacuum conditions can enhance charge-exchange beam losses and can lead to beam instabilities or even to beam abortion triggered by vacuum interlocks. Consequently, a dedicated measurement of heavy-ion induced molecular desorption in the GeV/u energy range is important for Large Hadron Collider (LHC) ion operation. In 2003, a desorption experiment was installed at the Super Proton Synchrotron to measure the beam-loss induced pressure rise of potential LHC collimator materials. Samples of bare graphite, sputter coated (Cu, TiZrV) graphite, and 316LN (low carbon with nitrogen) stainless steel were irradiated under grazing angle with 158 GeV/u indium ions. After a description of the new experimental setup, the results of the pressure rise measurements are presented, and the derived desorption yields are compared with data from other experiments.

  17. Study of pattern transition in nanopatterned Si(100) produced by impurity-assisted low-energy ion-beam erosion

    Science.gov (United States)

    Koyiloth Vayalil, Sarathlal; Gupta, Ajay; Roth, Stephan V.

    2017-04-01

    In this work, formation of self-organized Si nanostructures induced by pure Fe incorporation during normal incidence low-energy (1keV) Ar^+ ion bombardment is presented. It has been observed that the incorporation of Fe affects the evolution of the surface topography. The addition of Fe generates pronounced nanopatterns, such as dots, ripples and combinations of dots and ripples. The orientation of the ripple wave vector of the patterns formed is found to be in a direction normal to the Fe flow. The nanoripples with wavelength of the order of 39 nm produced is expected to be the lowest wavelength of the patterns reported on ion-beam-eroded structures under the incorporation of metallic impurities as per our knowledge. From the AFM and GISAXS analysis, it has been confirmed that the ripples formed are asymmetric in nature. The effect of the concentration of the Fe on morphological transition of the patterns has been studied using Rutherford backscattering measurements.

  18. Spatial pattern of mass loss processes across the Greenland Ice Sheet from the Little Ice Age to 2010

    Science.gov (United States)

    Kjaer, K.; Korsgaard, N. J.; Kjeldsen, K. K.; Bjork, A. A.; Khan, S. A.; Funder, S.; Nuth, C.; Larsen, N. K.; Vinther, B.; Andresen, C. S.; Long, A. J.; Woodroffe, S.; Hansen, E. S.; Odgaard, B. V.; Olsen, J.; Bamber, J. L.; van den Broeke, M. R.; Box, J. E.; Willerslev, E.

    2013-12-01

    The Greenland Ice Sheet loses mass through surface meltwater runoff and discharge from marine terminating outlet glaciers. The spatial variability and magnitude of these processes have been studied and described in detail for the past decades. Here, we combine the mass loss between the LIA to 2010 with a SMB model extending back to ~1900 in order to investigate the spatial distribution of mass loss processes. We use high quality aerial stereo photogrammetric imagery recorded between 1978 and 1987 to map morphological features such as trim lines and end moraines marking the maximum ice extent of the LIA, which enables us to obtain vertical point-based differences associated with former ice extent. These point measurements are combined with contemporary ice surface differences derived using NASA's Airborne Topographic Mapper (ATM) from 2003-2010, NASA's Ice, Cloud, and land Elevation Satellite (ICESat) from 2003-2009, NASA's Land, Vegetation, and Ice Sensor (LVIS) from 2010, and ASTER (Silcast AST14DMO) co-registered to ICESat, to estimate mass loss throughout the 20th and early 21st Century. The mass balance estimates of the GrIS since retreat from maximum LIA is combined with a SMB model for the period for three intervals, LIAmax (~1900) - 1978/87, 1978/87 - 2003, and 2003 - 2010. Across the GrIS the total mass loss if found to be spatially- and temporally variable. However, when assessing the mass loss due to SMB and mass loss due to dynamic ice loss, we find that that the ratios between these components are variable between the different sectors of the GrIS, e.g. in the southeast sector of the GrIS we find substantial mass loss, possibly driven by high precipitation rates but also the presence of a large number of marine terminating glaciers. Furthermore many areas currently undergoing changes correspond to those that experienced considerable thinning throughout the 20th century. Consequently, comparing the 20th century thinning pattern to that of the last decade

  19. Land use patterns and related carbon losses following deforestation in South America

    Science.gov (United States)

    De Sy, V.; Herold, M.; Achard, F.; Beuchle, R.; Clevers, J. G. P. W.; Lindquist, E.; Verchot, L.

    2015-12-01

    Land use change in South America, mainly deforestation, is a large source of anthropogenic CO2 emissions. Identifying and addressing the causes or drivers of anthropogenic forest change is considered crucial for global climate change mitigation. Few countries however, monitor deforestation drivers in a systematic manner. National-level quantitative spatially explicit information on drivers is often lacking. This study quantifies proximate drivers of deforestation and related carbon losses in South America based on remote sensing time series in a systematic, spatially explicit manner. Deforestation areas were derived from the 2010 global remote sensing survey of the Food and Agricultural Organisation Forest Resource Assessment. To assess proximate drivers, land use following deforestation was assigned by visual interpretation of high-resolution satellite imagery. To estimate gross carbon losses from deforestation, default Tier 1 biomass levels per country and eco-zone were used. Pasture was the dominant driver of forest area (71.2%) and related carbon loss (71.6%) in South America, followed by commercial cropland (14% and 12.1% respectively). Hotspots of deforestation due to pasture occurred in Northern Argentina, Western Paraguay, and along the arc of deforestation in Brazil where they gradually moved into higher biomass forests causing additional carbon losses. Deforestation driven by commercial cropland increased in time, with hotspots occurring in Brazil (Mato Grosso State), Northern Argentina, Eastern Paraguay and Central Bolivia. Infrastructure, such as urban expansion and roads, contributed little as proximate drivers of forest area loss (1.7%). Our findings contribute to the understanding of drivers of deforestation and related carbon losses in South America, and are comparable at the national, regional and continental level. In addition, they support the development of national REDD+ interventions and forest monitoring systems, and provide valuable input

  20. No-Loss Transportation of Water Droplets by Patterning a Desired Hydrophobic Path on a Superhydrophobic Surface.

    Science.gov (United States)

    Hu, Haibao; Yu, Sixiao; Song, Dong

    2016-07-26

    The directional transportation of droplets on solid surfaces is essential in a wide range of engineering applications. It is convenient to guide liquid droplets in a given direction by utilizing the gradient of wettability, by which the binding forces can be produced. In contrast to the mass-loss transportation of a droplet moving along hydrophilic paths on a horizontal superhydrophobic surface, we present no-loss transportation by fabricating a hydrophobic path on the same surface under tangential wind. In experimental exploration and theoretical analysis, the conditions of no-loss transportation of a droplet are mainly considered. We demonstrate that the lower (or upper) critical wind velocity, under which the droplet starts on the path (or is derailed from the path), is determined by the width of the path, the length of the contact area in the direction parallel to the path, the drift angle between the path and the wind direction, and the surface wettability of the pattern. Meanwhile, the no-loss transportation of water droplets along the desired path zigzagging on a superhydrophobic surface can be achieved steadily under appropriate conditions. We anticipate that such robust no-loss transportation will find an extensive range of applications.

  1. Developer molecular size dependence of pattern formation of polymer type electron beam resists with various molecular weights

    Science.gov (United States)

    Takayama, Tomohiro; Asada, Hironori; Kishimura, Yukiko; Ochiai, Shunsuke; Hoshino, Ryoichi; Kawata, Atsushi

    2016-05-01

    The sensitivity and the resolution are affected by not only the nature of the resist such as a chemical structure and a molecular weight but also the developing process such as a developer molecular size. Exposure characteristics of positive-tone polymer resists having various molecular weights (Mw's) ranging from 60 k to 500 k are investigated using different ester solvents as a developer. The line-and-space (L/S) patterns are exposed by the electron beam writing system with an acceleration voltage of 50 kV and the samples are developed by amyl acetate, hexyl acetate and heptyl acetate. The pattern shape becomes better and the surface of the resist also becomes smoother with increasing developer molecular size, though the exposure dose required for the formation of the L/S pattern increases. The dose margin of pattern formation is also wider in all the resists having the different molecular weights. The dissolution in the unexposed portions of the 60k-Mw resist for heptyl acetate is reduced significantly compared with those for amyl acetate and hexyl acetate. The improvement of the pattern shape and the increasing of dose margin are remarkable in the low molecular weight resist. The 3σ of line width roughness tends to be smaller in the higher molecular weight resist and with the larger molecular size developer. Exposure experiment of the 35 nm pitch pattern using the 500k-Mw resist developed at the room temperature is presented.

  2. Proton beam writing of microstructures in Agar gel for patterned cell growth

    Energy Technology Data Exchange (ETDEWEB)

    Larisch, Wolfgang, E-mail: wolfgang.larisch@studserv.uni-leipzig.de [Nukleare Festkoerperphysik, Universitaet Leipzig, Linnestr. 5, 04103 Leipzig (Germany); Koal, Torsten; Werner, Ronald; Hohlweg, Marcus; Reinert, Tilo; Butz, Tilman [Nukleare Festkoerperphysik, Universitaet Leipzig, Linnestr. 5, 04103 Leipzig (Germany)

    2011-10-15

    A rather useful prerequisite for many biological and biophysical studies, e.g., for cell-cell communication or neuronal networks, is confined cell growth on micro-structured surfaces. Solidified Agar layers have smooth surfaces which are electrically neutral and thus inhibit receptor binding and cell adhesion. For the first time, Agar microstructures have been manufactured using proton beam writing (PBW). In the irradiated Agar material the polysaccharides are split into oligosaccharides which can easily be washed off leaving Agar-free areas for cell adhesion. The beam diameter of 1 {mu}m allows the fabrication of compartments accommodating single cells which are connected by micrometer-sized channels. Using the external beam the production process is very fast. Up to 50 Petri dishes can be produced per day which makes this technique very suitable for biological investigations which require large throughputs.

  3. A beam test of prototype time projection chamber using micro-pattern gas detectors at KEK

    Indian Academy of Sciences (India)

    Makoto Kobayashi; on behalf of part of the ILC{TPC Collaboration

    2007-12-01

    We conducted a series of beam tests of prototype TPCs for the international linear collider (ILC) experiment, equipped with an MWPC, a MicroMEGAS, or GEMs as a readout device. The prototype operated successfully in a test beam at KEK under an axial magnetic field of up to 1 T. The analysis of data is now in progress and some of the preliminary results obtained with GEMs and MicroMEGAS are presented along with our interpretation. Also given is the extrapolation of the obtained spatial resolution to that of a large TPC expected as the central tracker of the ILC experiment.

  4. Weight Loss Associated With Different Patterns of Self-Monitoring Using the Mobile Phone App My Meal Mate

    Science.gov (United States)

    Carter, Michelle C; Burley, Victoria J

    2017-01-01

    Background Obesity is a major global public health issue due to its association with a number of serious chronic illnesses and its high economic burden to health care providers. Self-monitoring of diet has been consistently linked to weight loss. However, there is limited evidence about how frequently individuals need to monitor their diet for optimal weight loss. Objective The aim of this paper is to describe app usage frequency and pattern in the mobile phone arm of a previously conducted randomized controlled trial. The relationship between frequency and pattern of electronic dietary self-monitoring and weight loss is also investigated. Methods A randomized pilot trial comparing three methods of self-monitoring (mobile phone app, paper diary, Web-based) was previously conducted. Trial duration was 6 months. The mobile phone app My Meal Mate features an electronic food diary and encourages users to self-monitor their dietary intake. All food consumption data were automatically uploaded with a time and date stamp. Post hoc regression analysis of app usage patterns was undertaken in the My Meal Mate group (n=43; female: 77%, 33/43; white: 100%, 43/43; age: mean 41, SD 9 years; body mass index: mean 34, SD 4 kg/m2) to explore the relationship between frequency and pattern of electronic dietary self-monitoring and weight loss. Baseline characteristics of participants were also investigated to identify any potential predictors of dietary self-monitoring. Results Regression analysis showed that those in the highest frequency-of-use category (recorded ≥129 days on the mobile phone app) had a −6.4 kg (95% CI −10.0 to −2.9) lower follow-up weight (adjusted for baseline weight) than those in the lowest frequency-of-use category (recorded ≤42 days; Pconscientiousness, and consideration of future consequences were not statistically associated with extent of self-monitoring. Conclusions The results of this post hoc exploratory analysis indicate that duration and

  5. High-resolution direct-write patterning using focused ion beams

    NARCIS (Netherlands)

    Ocola, L.E.; Rue, C.; Maas, D.J.

    2014-01-01

    Over the last few years, significant improvements in sources, columns, detectors, control software, and accessories have enabled a wealth of new focused ion beam applications. In addition, modeling has provided many insights into ion-sample interactions and the resultant effects on the sample. With

  6. Controversy: Is there a role for adjuvants in the management of male pattern hair loss?

    Directory of Open Access Journals (Sweden)

    Rajendrasingh J Rajput

    2010-01-01

    Full Text Available Patients with hair loss are seeking treatment at a younger age and during earlier stages. Not all need hair transplants. Because of the lack of assured management and the fear of side-effects, patients are turning to ineffective alternative remedies from self-claimed experts. In this report, we discuss the available treatment options and how best they can be used in combination to produce satisfactory results. The traditional approach consists of administration of drugs such as minoxidil and finasteride. We propose a hypothesis that nutritional supplements, 2% ketoconazole shampoo and low-level laser therapy along with finasteride 1 mg used once in 3 days with 2% minoxidil used everyday, given in a cyclical medicine program may be useful to manage hair loss and achieve new hair growth. The scientific rationale for such an approach is explained. The need for further studies to establish the efficacy of the regime is stressed upon.

  7. A Real-Time FPGA based Algorithm for the combination of Beam Loss Acquisition Methods used for Measurement Dynamic Range expansion

    CERN Document Server

    Kwiatkowski, M; Alsdorf, M; Dehning, B; Vigano, W

    2012-01-01

    The aim of the Beam Loss Monitoring Dual Polarity (BLEDP) module under development at the European Organisation for Nuclear Research (CERN) is to measure and digitise with high precision the current produced by several types of beam loss detectors. The BLEDP module consists of eight analogue channels each with a fully differential integrator and an accompanying 16 bit ADC at the output of each analogue integrator. The on-board FPGA device controls the integral periods, instructs the ADC devices to perform measurements at the end of each period and collects the measurements. In the next stage it combines the number of charge and discharge cycles accounted in the last interval together with the cycle fractions observed using the ADC samples to produce a digitised high precision value of the charges collected. This paper describes briefly the principle of the fully differential integrator and focuses on the algorithm employed to process the digital data.

  8. Characteristics of Patients with Hearing Aids according to the Degree and Pattern of Hearing Loss

    OpenAIRE

    Byun, Young Seok; Kim, Sung Su; Park, Sang Hyun; Park, Eun Bin; Kim, Ho Joong; Kim, Sang Hoon; Yeo, Seung Geun

    2016-01-01

    Background and Objectives This study was designed to assess the characteristics of patients according to the degree and audiogram shape of hearing loss and the association of these characteristics with hearing aids (HA) choice, return rate, and cause of return. Subjects and Methods This study included 460 individuals who received HAs from 2011 to 2015. The relationships between type of HA and age, primary and accompanying symptoms, HA choice and return and cause of return were evaluated accor...

  9. Location, Timing, and Social Structure Patterns Related to Physical Activity Participation in Weight Loss Programs

    Science.gov (United States)

    Gay, Jennifer L.; Trevarthen, Grace

    2013-01-01

    Less than half of the adults in the United States meet national guidelines for physical activity. Physical activity programs can induce short-term improvements in physical activity. To develop effective interventions, researchers and practitioners should consider the timing, location, and social structure patterns of participants. Using a pretest,…

  10. Third-dimension information retrieval from a single convergent-beam transmission electron diffraction pattern using an artificial neural network

    Science.gov (United States)

    Pennington, Robert S.; Van den Broek, Wouter; Koch, Christoph T.

    2014-05-01

    We have reconstructed third-dimension specimen information from convergent-beam electron diffraction (CBED) patterns simulated using the stacked-Bloch-wave method. By reformulating the stacked-Bloch-wave formalism as an artificial neural network and optimizing with resilient back propagation, we demonstrate specimen orientation reconstructions with depth resolutions down to 5 nm. To show our algorithm's ability to analyze realistic data, we also discuss and demonstrate our algorithm reconstructing from noisy data and using a limited number of CBED disks. Applicability of this reconstruction algorithm to other specimen parameters is discussed.

  11. FORTRAN source listing for simulating three-dimensional convergent beam patterns with absorption by the Bloch wave method.

    Science.gov (United States)

    Zuo, J M; Gjonnes, K; Spence, J C

    1989-05-01

    The FORTRAN source code is given for a computer program that calculates the two-dimensional intensity distribution in convergent-beam transmission electron microdiffraction (CBED) patterns from perfect crystals. The program uses the eigenvalue or Bloch-wave method. It allows three-dimensional dynamical diffraction, and so includes all higher-order Laue zone effects without approximation. No symmetry reduction is included. The program accepts noncentrosymmetric or centrosymmetric crystal structures and allows absorption corrections to be included. It uses the "EISPACK" subroutines for the diagonalisation of a general complex matrix. Up to 100 CBED disks may be included. The code is also available via "Bitnet."

  12. Comparative study between cold plasma and hot plasma with ion beam and loss-cone distribution function by particle aspect approach

    Science.gov (United States)

    Patel, Soniya; Varma, P.; Tiwari, M. S.

    2011-03-01

    The electromagnetic ion-cyclotron (EMIC) instabilities with isotropic ion beam and general loss-cone distribution of cold and hot core plasmas are discussed. The growth rate, parallel and perpendicular resonance energies of the electromagnetic ion-cyclotron waves in a low β (ratio of plasma pressure to magnetic pressure), homogeneous plasma have been obtained using the dispersion relation for cold and hot plasmas. The wave is assumed to propagate parallel to the static magnetic field. The whole plasma is considered to consist of resonant and non-resonant particles permeated by isotropic ion beam. It is assumed that resonant particles and ion beam participate in energy exchange with the wave whereas non-resonant particles support the oscillatory motion of the wave. We determined the variation in energies and growth rate in cold and hot plasmas by the energy conservation method with a general loss-cone distribution function. The thermal anisotropy of the core plasma acts as a source of free energy for EMIC wave and enhances the growth rate. It is noted that the EMIC wave emissions occur by extracting energy of perpendicularly heated ions in the presence of up flowing ion beam and steep loss-cone distribution in the anisotropic magnetosphere. The effect of the steep loss-cone distribution is to enhance the growth rate of the EMIC wave. The heating of ions perpendicular and parallel to the magnetic field is discussed along with EMIC wave emission in the auroral acceleration region. The results are interpreted for the space plasma parameters appropriate to the auroral acceleration region of the earth's magnetoplasma.

  13. 预应力损失对连续梁桥内力的影响%Impacts of prestress loss on internal force of continuous beam bridge

    Institute of Scientific and Technical Information of China (English)

    曾辉; 杨凡坤

    2012-01-01

    Integrating with three-span continuous beam bridge on the extra large(48+80+48)m bridge,this paper discusses two conditions with and without considering prestress loss,introduces the composition and calculation method of prestress loss,and studies the impacts of prestress loss on internal force of continuous beam bridge,which has provided theoretical guidance for the design and calculation of three-span continuous beam bridge.%结合广东某特大桥(48+80+48)m三跨连续梁,从考虑和不考虑预应力损失两种情况进行了论述,介绍了预应力损失的组成和计算方法,进行了预应力损失对桥梁结构内力影响的研究,为三跨连续梁桥设计计算提供了理论指导。

  14. Defining the crack pattern of RC beams through the golden section

    Energy Technology Data Exchange (ETDEWEB)

    Fantilli, A P; Chiaia, B [Department of Structural and Geotechnical Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino 10129 (Italy); Cennamo, C, E-mail: alessandro.fantilli@polito.it [Department of ' Cultura del Progetto' , Universita di Napoli SUN, via San Lorenzo, Aversa 81031 (Italy)

    2011-07-19

    Both in architecture and arts, the golden section has been exclusively taken into consideration for its geometrical properties. Specifically, among all the proportions, the golden section can inspire beauty. Indeed, it has driven the construction of buildings for centuries. Nevertheless, as discussed for the first time in the present paper, static equilibrium of structures calls the golden section into play. This is the case of reinforced concrete beam in four point bending, whose average crack spacing in the constant moment zone increases of a factor equal to the irrational number 1.61803 when the geometrical dimensions of the beam are doubled. In other words, it can be argued that the centrality of golden section in the art of construction has profound physical meanings, as it can bring together the aesthetic of nature and architecture, and the equilibrium of stress flow in solid bodies.

  15. Massively parallel E-beam inspection: enabling next-generation patterned defect inspection for wafer and mask manufacturing

    Science.gov (United States)

    Malloy, Matt; Thiel, Brad; Bunday, Benjamin D.; Wurm, Stefan; Mukhtar, Maseeh; Quoi, Kathy; Kemen, Thomas; Zeidler, Dirk; Eberle, Anna Lena; Garbowski, Tomasz; Dellemann, Gregor; Peters, Jan Hendrik

    2015-03-01

    SEMATECH aims to identify and enable disruptive technologies to meet the ever-increasing demands of semiconductor high volume manufacturing (HVM). As such, a program was initiated in 2012 focused on high-speed e-beam defect inspection as a complement, and eventual successor, to bright field optical patterned defect inspection [1]. The primary goal is to enable a new technology to overcome the key gaps that are limiting modern day inspection in the fab; primarily, throughput and sensitivity to detect ultra-small critical defects. The program specifically targets revolutionary solutions based on massively parallel e-beam technologies, as opposed to incremental improvements to existing e-beam and optical inspection platforms. Wafer inspection is the primary target, but attention is also being paid to next generation mask inspection. During the first phase of the multi-year program multiple technologies were reviewed, a down-selection was made to the top candidates, and evaluations began on proof of concept systems. A champion technology has been selected and as of late 2014 the program has begun to move into the core technology maturation phase in order to enable eventual commercialization of an HVM system. Performance data from early proof of concept systems will be shown along with roadmaps to achieving HVM performance. SEMATECH's vision for moving from early-stage development to commercialization will be shown, including plans for development with industry leading technology providers.

  16. Beam loss caused by edge focusing of injection bump magnets and its mitigation in the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

    Science.gov (United States)

    Hotchi, H.; Tani, N.; Watanabe, Y.; Harada, H.; Kato, S.; Okabe, K.; Saha, P. K.; Tamura, F.; Yoshimoto, M.

    2016-01-01

    In the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex, transverse injection painting is utilized not only to suppress space-charge induced beam loss in the low energy region but also to mitigate foil scattering beam loss during charge-exchange injection. The space-charge induced beam loss is well minimized by the combination of modest transverse painting and full longitudinal painting. But, for sufficiently mitigating the foil scattering part of beam loss, the transverse painting area has to be further expanded. However, such a wide-ranging transverse painting had not been realized until recently due to beta function beating caused by edge focusing of pulsed injection bump magnets during injection. This beta function beating additionally excites random betatron resonances through a distortion of the lattice superperiodicity, and its resultant deterioration of the betatron motion stability causes significant extra beam loss when expanding the transverse painting area. To solve this issue, we newly installed pulse-type quadrupole correctors to compensate the beta function beating. This paper presents recent experimental results on this correction scheme for suppressing the extra beam loss, while discussing the beam loss and its mitigation mechanisms with the corresponding numerical simulations.

  17. Acoustic beam steering by light refraction: illustration with directivity patterns of a tilted volume photoacoustic source.

    Science.gov (United States)

    Raetz, Samuel; Dehoux, Thomas; Perton, Mathieu; Audoin, Bertrand

    2013-12-01

    The symmetry of a thermoelastic source resulting from laser absorption can be broken when the direction of light propagation in an elastic half-space is inclined relatively to the surface. This leads to an asymmetry of the directivity patterns of both compressional and shear acoustic waves. In contrast to classical surface acoustic sources, the tunable volume source allows one to take advantage of the mode conversion at the surface to control the directivity of specific modes. Physical interpretations of the evolution of the directivity patterns with the increasing light angle of incidence and of the relations between the preferential directions of compressional- and shear-wave emission are proposed. In order to compare calculated directivity patterns with measurements of normal displacement amplitudes performed on plates, a procedure is proposed to transform the directivity patterns into pseudo-directivity patterns representative of the experimental conditions. The comparison of the theoretical with measured pseudo-directivity patterns demonstrates the ability to enhance bulk-wave amplitudes and to steer specific bulk acoustic modes by adequately tuning light refraction.

  18. Results of the studies on energy deposition in IR6 superconducting magnets from continuous beam loss on the TCDQ system

    CERN Document Server

    Bracco, C; Presland, A; Redaelli, S; Sarchiapone, L; Weiler, T

    2007-01-01

    A single sided mobile graphite diluter block TCDQ, in combination with a two-sided secondary collimator TCS and an iron shield TCDQM, will be installed in front of the superconducting quadrupole Q4 magnets in IR6, in order to protect it and other downstream LHC machine elements from destruction in the event of a beam dump that is not synchronised with the abort gap. The TCDQ will be positioned close to the beam, and will intercept the particles from the secondary halo during low beam lifetime. Previous studies (1-4) have shown that the energy deposited in the Q4 magnet coils can be close to or above the quench limit. In this note the results of the latest FLUKA energy deposition simulations for Beam 2 are described, including an upgrade possibility for the TCDQ system with an additional shielding device. The results are discussed in the context of the expected performance levels for the different phases of LHC operation.

  19. Meal pattern alterations associated with intermittent fasting for weight loss are normalized after high-fat diet re-feeding.

    Science.gov (United States)

    Gotthardt, Juliet D; Bello, Nicholas T

    2017-03-03

    Alternate day, intermittent fasting (IMF) can be an effective weight loss strategy. However, the effects of IMF on eating behaviors are not well characterized. We investigated the acute and residual effects of IMF for weight loss on meal patterns in adult obese male C57BL/6 mice. After 8weeks of ad libitum high-fat diet to induce diet-induced obesity (DIO), mice were either continued on ad libitum high-fat diet (HFD) or placed on one of 5 diet strategies for weight loss: IMF of high-fat diet (IMF-HFD), pair-fed to IMF-HFD group (PF-HFD), ad libitum low-fat diet (LFD), IMF of low-fat diet (IMF-LFD), or pair-fed to IMF-LFD group (PF-LFD). After the 4-week diet period, all groups were refed the high-fat diet for 6weeks. By the end of the diet period, all 5 groups had lost weight compared with HFD group, but after 6weeks of HFD re-feeding all groups had similar body weights. On (Day 2) of the diet period, IMF-HFD had greater first meal size and faster eating rate compared with HFD. Also, first meal duration was greater in LFD and IMF-LFD compared with HFD. At the end of the diet period (Day 28), the intermittent fasting groups (IMF-HFD and IMF-LFD) had greater first meal sizes and faster first meal eating rate compared with their respective ad libitum fed groups on similar diets (HFD and LFD). Also, average meal duration was longer on Day 28 in the low-fat diet groups (LFD and IMF-LFD) compared with high-fat diet groups (HFD and IMF-HFD). After 6weeks of HFD re-feeding (Day 70), there were no differences in meal patterns in groups that had previously experienced intermittent fasting compared with ad libitum fed groups. These findings suggest that meal patterns are only transiently altered during alternate day intermittent fasting for weight loss in obese male mice.

  20. Loss of hippocampal function impairs pattern separation on a mouse touch-screen operant paradigm.

    Science.gov (United States)

    Josey, Megan; Brigman, Jonathan L

    2015-11-01

    The hippocampus is heavily involved in the learning and memory processes necessary to successfully encode environmental stimuli and representations over time. Impairment of hippocampal function is associated with numerous neuropsychiatric diseases and can lead to detriments in the quality of life. In order to take full advantage of preclinical models of these disorders, there is a need for the development of more refined measures of clinically relevant hippocampal behaviors. While arena-based navigation tasks have provided fundamental information regarding the role of the hippocampus in spatial memory, the development of automated operant variants have had mixed results. Recently, an automated touch-screen paradigm has been shown to be highly sensitive to hippocampal function in the rat and eliminated mediating strategies that arose in previous tasks. Here we show that mice with lesions encompassing the entire ventral portion of the dorsal hippocampus are impaired on pattern separation behavior using a delayed nonmatching-to-location (TUNL) adapted for mice. Lesioned mice readily acquired the task at control rates when separations were maximal and delay periods were short while decreasing separations significantly impaired lesion mice. However, in contrast to previously reported results in the rat, consistently increasing delays did not significantly impair performance in the lesion group. Presentation of a variable delay within a session significantly impaired performance in lesion mice across delay periods. The current results demonstrate the utility of a touch-screen paradigm for measuring hippocampal-dependent pattern separation in the mouse and establish the paradigm as an important platform for future studies in disease models.

  1. Patterns of Co-Occurring Gray Matter Concentration Loss across the Huntington Disease Prodrome

    Science.gov (United States)

    Ciarochi, Jennifer Ashley; Calhoun, Vince D.; Lourens, Spencer; Long, Jeffrey D.; Johnson, Hans J.; Bockholt, H. Jeremy; Liu, Jingyu; Plis, Sergey M.; Paulsen, Jane S.; Turner, Jessica A.

    2016-01-01

    Huntington disease (HD) is caused by an abnormally expanded cytosine–adenine–guanine (CAG) trinucleotide repeat in the HTT gene. Age and CAG-expansion number are related to age at diagnosis and can be used to index disease progression. However, observed onset-age variability suggests that other factors also modulate progression. Indexing prodromal (pre-diagnosis) progression may highlight therapeutic targets by isolating the earliest-affected factors. We present the largest prodromal HD application of the univariate method voxel-based morphometry (VBM) and the first application of the multivariate method source-based morphometry (SBM) to, respectively, compare gray matter concentration (GMC) and capture co-occurring GMC patterns in control and prodromal participants. Using structural MRI data from 1050 (831 prodromal, 219 control) participants, we characterize control-prodromal, whole-brain GMC differences at various prodromal stages. Our results provide evidence for (1) regional co-occurrence and differential patterns of decline across the prodrome, with parietal and occipital differences commonly co-occurring, and frontal and temporal differences being relatively independent from one another, (2) fronto-striatal circuits being among the earliest and most consistently affected in the prodrome, (3) delayed degradation in some movement-related regions, with increasing subcortical and occipital differences with later progression, (4) an overall superior-to-inferior gradient of GMC reduction in frontal, parietal, and temporal lobes, and (5) the appropriateness of SBM for studying the prodromal HD population and its enhanced sensitivity to early prodromal and regionally concurrent differences. PMID:27708610

  2. Polystyrene as a zwitter resist in electron beam lithography based electroless patterning of gold

    Indian Academy of Sciences (India)

    T Bhuvana; G U Kulkarni

    2008-06-01

    The resist action of polystyrene (w, 2,600,000) towards electroless deposition of gold on Si(100) surface following cross-linking by exposing to a 10 kV electron beam, has been investigated employing a scanning electron microscope equipped with electron beam lithography tool. With a low dose of electrons (21 C/cm2), the exposed regions inhibited the metal deposition from the plating solution due to cross-linking—typical of the negative resist behaviour of polystyrene, with metal depositing only on the developed Si surface. Upon increased electron dosage (160 C/cm2), however, Au deposition took place even in the exposed regions of the resist, thus turning it into a positive resist. Raman measurement revealed amorphous carbon present in the exposed region that promotes metal deposition. Further increase in dosage led successively to negative (220 C/cm2) and positive (13,500 C/cm2) resist states. The zwitter action of polystyrene resist has been exploited to create line gratings with pitch as low as 200 nm and gap electrodes down to 80 nm.

  3. Comparison of silicon and 4H silicon carbide patterning using focused ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Veerapandian, S.K.P. [Chair of Electron Devices, University of Erlangen-Nuremberg, Cauerstrasse 6, 91058 Erlangen (Germany); Beuer, S.; Rumler, M.; Stumpf, F. [Fraunhofer Institute for Integrated Systems and Device Technology (IISB), Schottkystrasse 10, 91058 Erlangen (Germany); Thomas, K.; Pillatsch, L.; Michler, J. [Empa Materials Science and Technology, Feuerwerkerstrasse 39, 3602 Thun (Switzerland); Frey, L. [Chair of Electron Devices, University of Erlangen-Nuremberg, Cauerstrasse 6, 91058 Erlangen (Germany); Fraunhofer Institute for Integrated Systems and Device Technology (IISB), Schottkystrasse 10, 91058 Erlangen (Germany); Rommel, M. [Fraunhofer Institute for Integrated Systems and Device Technology (IISB), Schottkystrasse 10, 91058 Erlangen (Germany)

    2015-12-15

    In this work, focused ion beam (FIB) milling of different structures is studied and compared for two different electronic materials, i.e., silicon (Si) and silicon carbide (SiC). Results show that the same processing parameters yield different trench cross sections for Si and SiC, even when the different material removal rates (MRR) are taken into account. In order to investigate more complex structures, nanocone arrays were fabricated in Si and SiC. The difference in the shape of the trench cross section and complex structures can be mainly explained by the significant difference in the angle dependent MRR for both materials. Other effects which occur during FIB irradiation by the non-ideal beam shape such as swelling and damage outside of the purposely processed region are emulated and sensitively studied by scanning probe microscopy techniques such as atomic force microscopy (in-line and off-line) and scanning spreading resistance microscopy, respectively, for SiC and the results are compared with those for Si.

  4. CSNS/RCS粒子散射束流损失研究%Study of Beam Loss due to Particle Scattering in CSNS/RCS

    Institute of Scientific and Technical Information of China (English)

    黄明阳; 王娜; 邱静; 王生; 黄楠

    2012-01-01

    在中国散裂中子源快循环同步加速器(CSNS/RCS)中,质子束流在加速过程中会与一些器件(如剥离膜、准直器、散射引出膜等)相互作用,产生粒子散射并导致束流损失.本工作首先利用ORBIT模拟RCS束流注入过程,并用FLUKA模拟注入束流穿过剥离膜的粒子散射过程,计算剥离膜散射所造成的束流损失.其次,模拟质子束流与准直器相互作用的粒子散射,计算质子束流与不同尺寸的次级准直器相互作用的吸收效率,作为对次级准直器优化的依据.最后,研究CSNS/RCS膜散射引出方案,利用FLUKA对不同引出方案进行模拟并比较,得到最佳的可行性方案.%In the Rapid Cycling Synchrotron of China Spallation Neutron Source (CSNS/ RCS) , the proton beam will interact with some devices, such as the stripping foil, beam collimator, and foil for scattering extraction. These interactions result in some particle scattering and beam losses. In this paper, firstly, the beam transportation in the injection procedure was simulated by ORBIT and the particle scattering due to the interaction between the beam and stripping foil was simulated by FLUKA, then the beam loss due to the foil scattering was calculated. Secondly, the particle scattering due to the proton beam interacting with the secondary collimator was simulated, and based on which, the secondary collimator was optimized by calculating the absorb efficiency. The optimization was done for the foil scattering extraction scheme by simulating and comparing different schemes with FLUKA.

  5. Resolution Improvement and Pattern Generator Development for theMaskless Micro-Ion-Beam Reduction Lithography System

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Ximan [Univ. of California, Berkeley, CA (United States)

    2006-05-18

    strategies have been studied. The dependence of the throughput with the exposure field size and the speed of the mechanical stage has been investigated. In order to perform maskless lithography, different micro-fabricated pattern generators have been developed for the MMRL system. Ion beamlet switching has been successfully demonstrated on the MMRL system. A positive bias voltage around 10 volts is sufficient to switch off the ion current on the micro-fabricated pattern generators. Some unexpected problems, such as the high-energy secondary electron radiations, have been discovered during the experimental investigation. Thermal and structural analysis indicates that the aperture displacement error induced by thermal expansion can satisfy the 3δ CD requirement for lithography nodes down to 25 nm. The cross-talking effect near the surface and inside the apertures of the pattern generator has been simulated in a 3-D ray-tracing code. New pattern generator design has been proposed to reduce the cross-talking effect. In order to eliminate the surface charging effect caused by the secondary electrons, a new beam-switching scheme in which the switching electrodes are immersed in the plasma has been demonstrated on a mechanically fabricated pattern generator.

  6. Loss of Atrx affects trophoblast development and the pattern of X-inactivation in extraembryonic tissues.

    Directory of Open Access Journals (Sweden)

    2006-04-01

    Full Text Available ATRX is an X-encoded member of the SNF2 family of ATPase/helicase proteins thought to regulate gene expression by modifying chromatin at target loci. Mutations in ATRX provided the first example of a human genetic disease associated with defects in such proteins. To better understand the role of ATRX in development and the associated abnormalities in the ATR-X (alpha thalassemia mental retardation, X-linked syndrome, we conditionally inactivated the homolog in mice, Atrx, at the 8- to 16-cell stage of development. The protein, Atrx, was ubiquitously expressed, and male embryos null for Atrx implanted and gastrulated normally but did not survive beyond 9.5 days postcoitus due to a defect in formation of the extraembryonic trophoblast, one of the first terminally differentiated lineages in the developing embryo. Carrier female mice that inherit a maternal null allele should be affected, since the paternal X chromosome is normally inactivated in extraembryonic tissues. Surprisingly, however, some carrier females established a normal placenta and appeared to escape the usual pattern of imprinted X-inactivation in these tissues. Together these findings demonstrate an unexpected, specific, and essential role for Atrx in the development of the murine trophoblast and present an example of escape from imprinted X chromosome inactivation.

  7. Production of nanohole/nanodot patterns on Si(001) by ion beam sputtering with simultaneous metal incorporation

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-GarcIa, J A; Gago, R; Caillard, R; Martin-Gago, J A; Palomares, F J; Fernandez, M; Vazquez, L [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones CientIficas, E-28049 Madrid (Spain); Redondo-Cubero, A [Centro de Micro-Analisis de Materiales, Universidad Autonoma de Madrid, E-28049 Madrid (Spain)], E-mail: lvb@icmm.csic.es

    2009-06-03

    We have established the conditions for which nanohole and nanodot patterns are produced on Si(001) surfaces by 1 keV Ar{sup +} ion beam sputtering (IBS) at normal incidence with an alternating cold cathode ion source (ACC-IS). Nanohole patterns are produced within a narrow IBS window for low ion fluxes (<100 {mu}A cm{sup -2}) and relatively low ion fluences (<10{sup 18} ions cm{sup -2}) whereas nanodot morphologies are produced above this window. The nanohole pattern is not stable after prolonged irradiation since it evolves to a nanodot morphology. Rutherford backscattering spectrometry (RBS) measurements show that nanohole patterns are produced when the metal content on the irradiated surfaces is higher (within (2.5-3.5 x 10{sup 15}) atoms cm{sup -2}) than in the case of nanodots (<2.5 x 10{sup 15} atoms cm{sup -2}). The different metal content is related to the ACC-IS operation, since the set-up provides simultaneous incorporation of Fe and Mo on the target surface from the erosion of the cathodes and sample holder, respectively. The role of metal incorporation on pattern selectivity has been corroborated qualitatively by extending the results obtained with the ACC-IS to a standard Kaufman-type source. In order to gain further information on the metal effects, chemical analysis of the surface has been performed to complement the compositional RBS results, showing for the first time the relevant participation of metal silicides. Further outlook and a discussion regarding the role of metal incorporation are also given.

  8. MeV Si ion beam implantation as an effective patterning tool for the localized formation of porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Punzon-Quijorna, E., E-mail: esther.punzon@uam.es [Universidad Autonoma de Madrid, Dept. Fisica Aplicada C-XII-104, 28049, Madrid (Spain); Centro de Micro-Analisis de Materiales, Cantoblanco 28049, Madrid (Spain); Torres-Costa, V.; Manso-Silvan, M.; Martin-Palma, R.J. [Universidad Autonoma de Madrid, Dept. Fisica Aplicada C-XII-104, 28049, Madrid (Spain); Climent-Font, A. [Universidad Autonoma de Madrid, Dept. Fisica Aplicada C-XII-104, 28049, Madrid (Spain); Centro de Micro-Analisis de Materiales, Cantoblanco 28049, Madrid (Spain)

    2012-07-01

    Porous silicon (PS), in the form of single layer and multilayer structures, is a low-cost nanomaterial with applications in a wide range of fields. Hence, there is an increasing interest on the fabrication of laterally patterned PS structures. In biophysics for example, PS is a promising material for the development of low cost optical biochips, due to its remarkable biocompatibility and adjustable surface chemistry and optical properties. However, conventional lithography processes have shown to be not suitable for the proper patterning of PS. In this work, implantation of MeV Si ions is proposed as an effective tool for the localized formation of PS in the micrometer range. As previously reported by other groups, irradiation of silicon with H and He keV ions can inhibit the formation of PS. In the case of heavier ions, its higher damage efficiency allows for lower implantation doses to achieve PS growth inhibition, which allows shorter process times, and at the same time provides good lateral resolution below the micrometric range. Besides, the usage of ions of the same elementary nature as the target material avoids inconvenient side effects that may be ascribed to the implanted species. Two dimensional PS patterns with feature size of few micrometers have been successfully fabricated. Fluorescence and scanning electron microscopy reveal the proper transfer of different mask motifs into a PS/silicon patterned structure. Patterns present well defined lateral contrast and flat surface with no significant height variations, mandatory features for the development of PS based biochips. A resistivity increase has been observed on irradiated samples which could explain the inhibition of PS formation. This effect is attributed to dopant deactivation by the ion beam, since backscattering channeling measurements show no significant lattice damage.

  9. Ferromagnetic resonance response of electron-beam patterned arrays of ferromagnetic nanoparticles

    Science.gov (United States)

    Jung, Sukkoo; Watkins, Byron; Feller, Jeffrey; Ketterson, John; Chandrasekhar, Venkat

    2001-03-01

    We report on the fabrication and the dynamic magnetic properties of periodic permalloy dot arrays. Electron-beam lithography and e-gun evaporation have been used to make the arrays with the aspect ratio of 2 (dot diameter : 40 nm, height : 80 nm) and periods of 100 - 200 nm. The magnetic properties of the arrays and their interactions have been investigated by ferromagnetic resonance (FMR), magnetic force microscopy (MFM), and SQUID magnetometry. The measured FMR data show that the position and magnitude of resonant absorption peaks strongly depend on the angle between magnetic field and the lattice structure. The results of dot arrays with various kinds of structural parameters will be presented. Supported by Army Research Office, DAAD19-99-1-0334/P001

  10. Patterned growth of InGaN/GaN quantum wells on freestanding GaN grating by molecular beam epitaxy

    OpenAIRE

    Wang Yongjin; Hu Fangren; Hane Kazuhiro

    2011-01-01

    Abstract We report here the epitaxial growth of InGaN/GaN quantum wells on freestanding GaN gratings by molecular beam epitaxy (MBE). Various GaN gratings are defined by electron beam lithography and realized on GaN-on-silicon substrate by fast atom beam etching. Silicon substrate beneath GaN grating region is removed from the backside to form freestanding GaN gratings, and the patterned growth is subsequently performed on the prepared GaN template by MBE. The selective growth takes place wit...

  11. Assessing electron beam sensitivity for SrTiO3 and La0.7Sr0.3MnO3 using electron energy loss spectroscopy.

    Science.gov (United States)

    Nord, Magnus; Vullum, Per Erik; Hallsteinsen, Ingrid; Tybell, Thomas; Holmestad, Randi

    2016-10-01

    Thresholds for beam damage have been assessed for La0.7Sr0.3MnO3 and SrTiO3 as a function of electron probe current and exposure time at 80 and 200kV acceleration voltage. The materials were exposed to an intense electron probe by aberration corrected scanning transmission electron microscopy (STEM) with simultaneous acquisition of electron energy loss spectroscopy (EELS) data. Electron beam damage was identified by changes of the core loss fine structure after quantification by a refined and improved model based approach. At 200kV acceleration voltage, damage in SrTiO3 was identified by changes both in the EEL fine structure and by contrast changes in the STEM images. However, the changes in the STEM image contrast as introduced by minor damage can be difficult to detect under several common experimental conditions. No damage was observed in SrTiO3 at 80kV acceleration voltage, independent of probe current and exposure time. In La0.7Sr0.3MnO3, beam damage was observed at both 80 and 200kV acceleration voltages. This damage was observed by large changes in the EEL fine structure, but not by any detectable changes in the STEM images. The typical method to validate if damage has been introduced during acquisitions is to compare STEM images prior to and after spectroscopy. Quantifications in this work show that this method possibly can result in misinterpretation of beam damage as changes of material properties.

  12. Focused ion beam patterned Fe thin films A study by selective area Stokes polarimetry and soft x-Ray microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cook, P. J.; Shen, T. H.; Grundy, P. J.; Im, M.-Y.; Fischer, P.; Morton, S. A.; Kilcoyne, A. L. D.

    2010-11-14

    We demonstrate the potential to modify the magnetic behavior and structural properties of ferromagnetic thin films using focused ion beam 'direct-write' lithography. Patterns inspired by the split-ring resonators often used as components in meta-materials were defined upon 15 nm Fe films using a 30 keV Ga{sup +} focused ion beam at a dose of 2 x 10{sup 16} ions cm{sup -2}. Structural, chemical and magnetic changes to the Fe were studied using transmission soft X-ray microscopy at the ALS, Berkeley CA. X-ray absorption spectra showed a 23% reduction in the thickness of the film in the Ga irradiated areas, but no chemical change to the Fe was evident. X-ray images of the magnetic reversal process show domain wall pinning around the implanted areas, resulting in an overall increase in the coercivity of the film. Transmission electron microscopy showed significant grain growth in the implanted regions.

  13. In situ patterning of organic molecules in aqueous solutions using an inverted electron-beam lithography system

    Science.gov (United States)

    Miyazako, Hiroki; Ishihara, Kazuhiko; Mabuchi, Kunihiko; Hoshino, Takayuki

    2016-06-01

    A method for in situ controlling the detachment and deposition of organic molecules such as sugars and biocompatible polymers in aqueous solutions by electron-beam (EB) scan is proposed and evaluated. It was demonstrated that EB irradiation could detach 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers from a silicon nitride membrane. Moreover, organic molecules such as cationic polymers and sugars could be deposited on the membrane by EB irradiation. Spatial distributions of scattered electrons were numerically simulated, and acceleration voltage dependences of the detachment and deposition phenomena were experimentally measured. The simulations and experimental results suggest that the detachment of MPC polymers is mainly due to electrical effects of primary electrons, and that the deposition of organic molecules is mainly due to chemical reactions induced by primary electrons. In view of these findings, the proposed method can be applied to in situ and nanoscale patterning such as the fabrication of cell scaffolds.

  14. Electron-beam patterned self-assembled monolayers as templates for Cu electrodeposition and lift-off

    Directory of Open Access Journals (Sweden)

    Zhe She

    2012-02-01

    Full Text Available Self-assembled monolayers (SAMs of 4'-methylbiphenyl-4-thiol (MBP0 adsorbed on polycrystalline gold substrates served as templates to control electrochemical deposition of Cu structures from acidic solution, and enabled the subsequent lift-off of the metal structures by attachment to epoxy glue. By exploiting the negative-resist behaviour of MBP0, the SAM was patterned by means of electron-beam lithography. For high deposition contrast a two-step procedure was employed involving a nucleation phase around −0.7 V versus Cu2+/Cu and a growth phase at around −0.35 V versus Cu2+/Cu. Structures with features down to 100 nm were deposited and transferred with high fidelity. By using substrates with different surface morphologies, AFM measurements revealed that the roughness of the substrate is a crucial factor but not the only one determining the roughness of the copper surface that is exposed after lift-off.

  15. Rapid and direct micro-machining/patterning of polymer materials by oxygen MeV ion beam irradiation through masks

    Energy Technology Data Exchange (ETDEWEB)

    Brun, S., E-mail: sebastien.brun@he-arc.ch [Institut des Microtechnologies Appliquees, Eplatures-Grise 17, 2300 La Chaux-de-Fonds (Switzerland); Guibert, G. [Institut des Microtechnologies Appliquees, Eplatures-Grise 17, 2300 La Chaux-de-Fonds (Switzerland); Meunier, C. [Universite de Franche Comte, Institut FEMTO-ST, UMR 6174 CNRS, 4 Place Tharradin, BP 71427, 25211 Montbeliard (France); Guibert, E.; Keppner, H.; Mikhailov, S. [Institut des Microtechnologies Appliquees, Eplatures-Grise 17, 2300 La Chaux-de-Fonds (Switzerland)

    2011-10-15

    PTFE (PolyTetraFluoroEthylene), often called Teflon, is a well-known polymer for being a non-stick material with good thermal properties. Moreover, PTFE is biocompatible and especially it is a cyto-compatible polymer. To enable bonding, a chemical etching based on sodium solutions is generally used to modify surfaces. In this paper we study the etching of PTFE using an oxygen ion beam in the MeV energy range. We present micro-patterning of PTFE through masks with two fluences of 5 x 10{sup 15} and 1 x 10{sup 16} ion cm{sup -2}. As is demonstrated the use of a mask allows structuring of large areas while maintaining a distance between the mask and sample makes industrial applications possible.

  16. Failure pattern implications following external beam irradiation of prostate cancer: long-term follow-up and indications of cure.

    Science.gov (United States)

    Hanlon, A L; Hanks, G E

    2000-04-01

    The purpose of this study was to present patterns and risk of biochemical failure following external beam irradiation of prostate cancer and to make comparisons to a published modern radical prostatectomy series. Between January 1987 and December 1994, 328 men were treated definitively at Fox Chase Cancer Center for localized prostate cancer using conventional or three-dimensional conformal radiotherapy. The median biochemical follow-up was 6.4 years, with all patients having at least 5 years follow-up. Two prognostic patient groups were established on the basis of proportional hazards modeling that considered treatment and presenting tumor characteristics. For each of the two prognostic groups, biochemical failure and hazard functions were estimated using the ASTRO consensus definition of failure and life table methodology. Failure risk comparisons were made to modern published radical prostatectomy series. Multivariate analysis demonstrated the independent predictive power of pretreatment PSA level, palpation stage, Gleason score, and dose. Thus, the favorable prognosis group, Group I, consisted of 83 patients who were treated with a dose level > or = 74 Gy and who presented with PSA levels or = 20 ng/ml, T2B/T3 tumor, Gleason score 7-10, dose tapering to a low rate at 4 years with no failures observed after 6 years. Differences in patterns of failure by prognostic group show maximum risk of failure at 24 months (median, 31 months) for Group I, and 12 to 36 months (median, 22 months) for Group II. Group II reaches low levels of risk at 6 years, in contrast to 4 years for the patients with a more favorable prognosis. We concluded that patients treated with external beam radiation alone show little risk of failure after 4 to 6 years. This result suggests that the 5-year bNED control rate approximates the eventual cure rate of prostate cancer.

  17. Absolute cascade-free cross-sections for the 2S to 2P transition in Zn(+) using electron-energy-loss and merged-beams methods

    Science.gov (United States)

    Smith, Steven J.; Man, K.-F.; Chutjian, A.; Mawhorter, R. J.; Williams, I. D.

    1991-01-01

    Absolute cascade-free excitation cross-sections in an ion have been measured for the resonance 2S to 2P transition in Zn(+) using electron-energy-loss and merged electron-ion beams methods. Measurements were carried out at electron energies of below threshold to 6 times threshold. Comparisons are made with 2-, 5-, and 15-state close-coupling and distorted-wave theories. There is good agreement between experiment and the 15-state close-coupling cross-sections over the energy range of the calculations.

  18. Emission and propagation of Saturn kilometric radiation: magneto-ionic modes, beaming pattern and polarization state

    CERN Document Server

    Lamy, L; Zarka, P; Canu, P; Schippers, P; Kurth, W S; Mutel, R L; Gurnett, D A; Menietti, J D; Louarn, P

    2011-01-01

    The Cassini mission crossed the source region of the Saturn kilometric radiation (SKR) on 17 October 2008. On this occasion, the Radio and Plasma Wave Science (RPWS) experiment detected both local and distant radio sources, while plasma parameters were measured in situ by the magnetometer (MAG) and the Cassini Plasma Spectrometer (CAPS). A goniopolarimetric inversion was applied to RPWS 3-antenna electric measurements to determine the wave vector k and the complete state of polarization of detected waves. We identify broadband extraordinary (X) as well as narrowband ordinary (O) mode SKR at low frequencies. Within the source region, SKR is emitted just above the X mode cutoff frequency in a hot plasma, with a typical electron-to-wave energy conversion efficiency of 1% (2% peak). The knowledge of the k-vector is then used to derive the locus of SKR sources in the kronian magnetosphere, that shows X and O components emanating from the same regions. We also compute the associated beaming angle at the source thet...

  19. Beam losses from ultra-peripheral nuclear collisions between $^{208}$Pb$^{82+}$ ions in the Large Hadron Collider and their alleviation

    CERN Document Server

    Bruce, R; Jowett, J; Bocian, D; CERN. Geneva. BE Department

    2009-01-01

    Electromagnetic interactions between colliding heavy ions at the Large Hadron Collider (LHC) at CERN will give rise to localized beam losses that may quench superconducting magnets, apart from contributing significantly to the luminosity decay. To quantify their impact on the operation of the collider, we have used a three-step simulation approach, which consists of optical tracking, a Monte-Carlo shower simulation and a thermal network model of the heat flow inside a magnet. We present simulation results for the case of Pb ion operation in the LHC, with focus on the ALICE interaction region, and show that the expected heat load during nominal Pb operation is 40% above the quench level. This limits the maximum achievable luminosity. Furthermore, we discuss methods of monitoring the losses and possible ways to alleviate their effect.

  20. External beam irradiation for retinoblastoma: patterns of failure and dose-response analysis

    Energy Technology Data Exchange (ETDEWEB)

    Foote, R.L.; Garretson, B.R.; Schomberg, P.J.; Buskirk, S.J.; Robertson, D.M.; Earle, J.D.

    1989-03-01

    Eighteen children with retinoblastoma (25 eyes) were treated with external beam radiation at the Mayo Clinic between January 1977 and January 1987; 15 eyes were in groups I to III and 10 were in groups IV and V. The median number of tumors per eye was 3. Radiation therapy consisted of 4- or 6-MV photons. Doses varied from 39 to 51 Gy in 1.8- to 3.0-Gy fractions. Fourteen eyes were treated through lateral fields by anterior segment-sparing techniques, and 11 eyes were treated by an anterior approach with no attempt at anterior segment sparing. All patients survived (median follow-up, 31.5 months). Cataracts developed in five eyes at a median of 23 months, four in eyes treated with anterior segment-sparing techniques. Of the 15 group I to III eyes, 6 required additional treatment; 4 were salvaged with cryotherapy or photocoagulation and 2 were enucleated. Of the 10 group IV and V eyes, 8 required additional treatment; 4 were salvaged with cryotherapy or photocoagulation, 1 with persistent disease is being followed closely, and 3 were enucleated. Ten (71%) of the 14 eyes treated with anterior segment-sparing techniques required additional treatment. Four (36%) of the 11 eyes treated with an anterior approach required additional treatment. Ninety percent of the tumors 10 disc diameters or smaller (1 disc diameter = 1.6 mm) were controlled independently of dose and fractionation used when they were not in the low-dose area of the anterior retina of an eye treated with an anterior segment-sparing technique. We find that use of lateral, anterior segment-sparing techniques has a high risk of anterior retinal tumor development and cataract formation and should be abandoned in favor of techniques that treat the entire retina.

  1. Square shaped flat-top beam in refractive beam shapers

    Science.gov (United States)

    Laskin, Alexander; Laskin, Vadim; Ostrun, Aleksei

    2015-08-01

    Lossless transformation of round Gaussian to square shaped flat-top collimated beam is important in building highpower solid state laser systems to improve optical pumping or amplification. There are industrial micromachining applications like scribing, display repair, which performance is improved when a square shaped spot with uniform intensity is created. Proved beam shaping solutions to these techniques are refractive field mapping beam shapers having some important features: flatness of output phase front, small output divergence, high transmittance, extended depth of field, operation with TEM00 and multimode lasers. Usual approach to design refractive beam shapers implies that input and output beams have round cross-section, therefore the only way to create a square shaped output beam is using a square mask, which leads to essential losses. When an input laser beam is linearly polarized it is suggested to generate square shaped flat-top output by applying beam shaper lenses from birefringent materials or by using additional birefringent components. Due to birefringence there is introduced phase retardation in beam parts and is realized a square shaped interference pattern at the beam shaper output. Realization of this approach requires small phase retardation, therefore weak birefringence effect is enough and birefringent optical components, operating in convergent or divergent beams, can be made from refractive materials, which crystal optical axis is parallel to optical axis of entire beam shaper optical system. There will be considered design features of beam shapers creating square shaped flat-top beams. Examples of real implementations and experimental results will be presented as well.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-08-03

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

  3. Monte Carlo Studies of the Radiation Fields in the Linac Coherent Light Source Undulators and of the Corresponding Signals in the Cerenkov Beam Loss Monitors

    Energy Technology Data Exchange (ETDEWEB)

    Santana Leitner, Mario; Fasso, Alberto; Fisher, Alan S.; Nuhn, Heinz D.; /SLAC; Dooling, Jeffrey C.; Berg, William; Yang, Bin X.; /Argonne

    2010-09-14

    In 2009 the Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Center started free electron laser (FEL) operation. In order to continue to produce the bright and short-pulsed x-ray laser demanded by FEL scientists, this pioneer hard x-ray FEL requires a perfectly tailored magnetic field at the undulators, so that the photons generated at the electron wiggling path interact at the right phase with the electron beam. In such a precise system, small (>0.01%) radiation-induced alterations of the magnetic field in the permanent magnets could affect FEL performance. This paper describes the simulation studies of radiation fields in permanent magnets and the expected signal in the detectors. The transport of particles from the radiation sources (i.e. diagnostic insert) to the undulator magnets and to the beam loss monitors (BLM) was simulated with the intra nuclear cascade codes FLUKA and MARS15. In order to accurately reproduce the optics of LCLS, lattice capabilities and magnetic fields were enabled in FLUKA and betatron oscillations were validated against reference data. All electron events entering the BLMs were printed in data files. The paper also introduces the Radioactive Ion Beam Optimizer (RIBO) Monte Carlo 3-D code, which was used to read from the event files, to compute Cerenkov production and then to simulate the optical coupling of the BLM detectors, accounting for the transmission of light through the quartz.

  4. Electron Beam Lifetime in SPEAR3: Measurement and Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Corbett, J.; Huang, X.; Lee, M.; Lui, P.; /SLAC; Sayyar-Rodsari, B.; /Pavilon Tech., Austin

    2007-12-19

    In this paper we report on electron beam lifetime measurements as a function of scraper position, RF voltage and bunch fill pattern in SPEAR3. We then outline development of an empirical, macroscopic model using the beam-loss rate equation. By identifying the dependence of loss coefficients on accelerator and beam parameters, a numerically-integrating simulator can be constructed to compute beam decay with time. In a companion paper, the simulator is used to train a parametric, non-linear dynamics model for the system [1].

  5. Range verification of passively scattered proton beams based on prompt gamma time patterns

    Science.gov (United States)

    Testa, Mauro; Min, Chul Hee; Verburg, Joost M.; Schümann, Jan; Lu, Hsiao-Ming; Paganetti, Harald

    2014-07-01

    We propose a proton range verification technique for passive scattering proton therapy systems where spread out Bragg peak (SOBP) fields are produced with rotating range modulator wheels. The technique is based on the correlation of time patterns of the prompt gamma ray emission with the range of protons delivering the SOBP. The main feature of the technique is the ability to verify the proton range with a single point of measurement and a simple detector configuration. We performed four-dimensional (time-dependent) Monte Carlo simulations using TOPAS to show the validity and accuracy of the technique. First, we validated the hadronic models used in TOPAS by comparing simulations and prompt gamma spectrometry measurements published in the literature. Second, prompt gamma simulations for proton range verification were performed for the case of a water phantom and a prostate cancer patient. In the water phantom, the proton range was determined with 2 mm accuracy with a full ring detector configuration for a dose of ~2.5 cGy. For the prostate cancer patient, 4 mm accuracy on range determination was achieved for a dose of ~15 cGy. The results presented in this paper are encouraging in view of a potential clinical application of the technique.

  6. Length and Geometric Patterns of the Greater Palatine Canal Observed in Cone Beam Computed Tomography

    Directory of Open Access Journals (Sweden)

    Karen Howard-Swirzinski

    2010-01-01

    Full Text Available The greater palatine canal is an important anatomical structure that is often utilized as a pathway for infiltration of local anesthesia to affect sensation and hemostasis. Increased awareness of the length and anatomic variation in the anatomy of this structure is important when performing surgical procedures in this area (e.g., placement of osseointegrated dental implants. We examined the anatomy of the greater palatine canal using data obtained from CBCT scans of 500 subjects. Both right and left canals were viewed (=1000 in coronal and sagittal planes, and their paths and lengths determined. The average length of the greater palatine canal was 29 mm (±3 mm, with a range from 22 to 40 mm. Coronally, the most common anatomic pattern consisted of the canal traveling inferior-laterally for a distance then directly inferior for the remainder (43.3%. In the sagittal view, the canal traveled most frequently at an anterior-inferior angle (92.9%.

  7. Tropical Cyclone Track Convergence Patterns, Arctic Sea-Ice Loss, and Superstorm Sandy: Is There a Connection?

    Science.gov (United States)

    Barnes, C. C.; Francis, J. A.; Byrne, J. M.; Graham, J. R.; McDaniel, S. A.

    2013-12-01

    The potential for disruption to populations and food production due to global climate change will be catastrophic in some regions. Among the most vulnerable regions are those impacted by intensifying or changing tropical cyclones (TC). The objective of this research is to identify historical trends in TC tracks and regional circulation patterns that may forecast increasing risks due to TC intensification under global climate warming. We carry out spatial and temporal analysis of the 1979 - 2011 International Best Track Archive for Climate Stewardship (IBTrACS) historical hurricane database. The data were divided into several subsets to allow analysis of trend in: (i) early (JJAS) and late (OND) seasonal trends; and (ii) multi-year intervals (1979-95 and 1996-2011) to differentiate possible long term trends, if any. Geographical Information Systems (GIS) overlay analysis of the IBTrACS 64 knot hurricane wind radii data identified varying levels of historical tropical cyclone track convergence in the North Atlantic (NA) basin. Results of the track convergence analysis provide a first order analysis regarding changing potential population vulnerabilities due to changing seasonal or long-term tropical cyclone activity. During the summer of 2012, the amount of sea ice on the Arctic Ocean was diminished to about half of its normal extent and 25% of its normal volume relative to the nearly steady conditions that existed before the 1980s. This record loss continues an inexorable decline observed during recent decades. The dramatic increase in open water allows much more solar energy absorption at high latitude. Most of this extra heat returns to the atmosphere in autumn, contributing to the Arctic's rate of warming; exceeding that of mid-latitudes by a factor of two to three, a phenomenon called Arctic Amplification (AA). During October 2012, prior to the arrival of Superstorm Sandy along the eastern seaboard, AA was particularly strong, resulting in a substantial

  8. BNL alternating gradient synchrotron with four helical magnets to minimize the losses of the polarized proton beam

    Science.gov (United States)

    Tsoupas, N.; Huang, H.; MacKay, W. W.; Meot, F.; Roser, T.; Trbojevic, D.

    2013-04-01

    The principle of using multiple partial helical magnets to preserve the polarization of the proton beam during its acceleration was applied successfully to the alternating gradient synchrotron (AGS) which currently operates with two partial helical magnets. In this paper we further explore this idea by using four partial helical magnets placed symmetrically in the AGS ring. This provides many advantages over the present setup of the AGS, which uses two partial helical magnets. First, the symmetric placement of the four helical magnets and their relatively lower field of operation allows for better control of the AGS optics with reduced values of the beta functions especially near beam injection and allows both the vertical and horizontal tunes to be placed within the “spin tune gap,” therefore eliminating the horizontal and vertical intrinsic spin resonances of the AGS during the acceleration cycle. Second, it provides a wider spin tune gap. Third, the vertical spin direction during beam injection and extraction is closer to vertical. Although the spin tune gap, which is created with four partial helices, can also be created with a single or two partial helices, the high field strength of a single helical magnet which is required to generate such a spin tune gap makes the use of the single helical magnet impractical, and that of the two helical magnets rather difficult. In this paper we will provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and compare them with those from the present setup of the AGS that uses two partial helical magnets. Although in this paper we specifically discuss the effect of the four partial helices on the AGS, this method which can eliminate simultaneously the vertical and horizontal intrinsic spin resonances is a general method and can be applied to any medium energy synchrotron which operates in similar energy range like the AGS and provides the required space to accommodate the four

  9. A novel raster-scanning method to fabricate ultra-fine cross-gratings for the generation of electron beam moiré fringe patterns

    Science.gov (United States)

    Lang, F. C.; Zhao, Y. R.; Xing, Y. M.; Liu, F.; Hou, X. H.; Zhu, J.; Li, J. J.; Yang, S. T.

    2016-11-01

    The resolution of the electron beam moiré method depends on the line frequency of the grating. Recently, more and more effort has been devoted to increase the frequency, and a novel method for producing high-resolution electron beam gratings is presented in this work. Cross-gratings with a frequency up to 14,832 lines/mm (67 nm pitch) were successfully fabricated using a common scanning electron microscope without a dedicated pattern generation system. The quality of the grating was high enough to produce high-quality moiré fringe patterns. In this method, the ultra-fine cross-grating can be fabricated only through one-directional scanning on the resist, which can improve the grating quality and significantly reduces the fabrication time. The number of control parameters for grating fabrication could be reduced to two compared to the six parameters required by conventional methods, which facilitates the use of the electron beam moiré method. The frequency of the fabricated grating is linearly proportional to the exposure magnification. Thus, the frequency of the grating can be accurately predetermined, and the null field can be easily obtained in the electron beam moiré method. The quality of the fabricated gratings was illustrated by the obtained micrographs and moiré fringe patterns. The full-field local strain near an induced crack was studied to verify the application potential of this method.

  10. Complex Evolutionary and Genetic Patterns Characterize the Loss of Scleral Ossification in the Blind Cavefish Astyanax mexicanus.

    Directory of Open Access Journals (Sweden)

    Kelly E O'Quin

    factors which may control the severity and onset of lens degeneration in cavefishes. We conclude that complex evolutionary and genetic patterns underlie the loss of scleral ossification in Astyanax cavefish.

  11. Design beam shapers with double freeform surfaces to form a desired wavefront with prescribed illumination pattern by solving a Monge-Ampère type equation

    Science.gov (United States)

    Chang, Shengqian; Wu, Rengmao; An, Li; Zheng, Zhenrong

    2016-12-01

    Beam shaping, in other words, the control of both intensity distribution and phase profile, has a wide range of applications. In this paper, double freeform surfaces are utilized to shape collimated beams, realizing an arbitrary output wavefront with desired illumination pattern. Freeform surfaces are designed by solving a second order partial differential equation (PDE) of the Monge-Ampère (MA) type, without the limitation of symmetry or paraxial approximation. The mathematical derivation of the PDE is based on the Snell’s law, the energy conservation law along infinitesimal tubes of rays and the constancy of the OPL. The PDE is discretized with a finite difference scheme into a system of nonlinear equations, which can be numerically solved by Newton’s method. Since Newton’s method requires a good initialization for the iteration, a simultaneously point-by-point method, based on ray mapping, is employed to find the initial iterate. Different design examples are given to demonstrate the effectiveness and wide application of our method, transforming a collimated Gaussian beam into a spherical wavefront with uniform illumination patterns. Variable-sized uniform illumination pattern can be obtained by moving the observation plane due to a potential benefit of the spherical output wavefront.

  12. Self-organised silicide nanodot patterning by medium-energy ion beam sputtering of Si(100): local correlation between the morphology and metal content.

    Science.gov (United States)

    Redondo-Cubero, A; Galiana, B; Lorenz, K; Palomares, F J; Bahena, D; Ballesteros, C; Hernandez-Calderón, I; Vázquez, L

    2016-11-01

    We have produced self-organised silicide nanodot patterns by medium-energy ion beam sputtering (IBS) of silicon targets with a simultaneous and isotropic molybdenum supply. Atomic force microscopy (AFM) studies show that these patterns are qualitatively similar to those produced thus far at low ion energies. We have determined the relevance of the ion species on the pattern ordering and properties. For the higher ordered patterns produced by Xe(+) ions, the pattern wavelength depends linearly on the ion energy. The dot nanostructures are silicide-rich as assessed by x-ray photoelectron spectroscopy (XPS) and emerge in height due to their lower sputtering yield, as observed by electron microscopy. Remarkably, a long wavelength corrugation is observed on the surface which is correlated with both the Mo content and the dot pattern properties. Thus, as assessed by electron microscopy, the protrusions are Mo-rich with higher and more spaced dots on their surface whereas the valleys are Mo-poor with smaller dots that are closer to each other. These findings indicate that there is a correlation between the local metal content of the surface and the nanodot pattern properties both at the nanodot and the large corrugation scales. These results contribute to advancing the understanding of this interesting nanofabrication method and aid in developing a comprehensive theory of nanodot pattern formation and evolution.

  13. Self-organised silicide nanodot patterning by medium-energy ion beam sputtering of Si(100): local correlation between the morphology and metal content

    Science.gov (United States)

    Redondo-Cubero, A.; Galiana, B.; Lorenz, K.; Palomares, FJ; Bahena, D.; Ballesteros, C.; Hernandez-Calderón, I.; Vázquez, L.

    2016-11-01

    We have produced self-organised silicide nanodot patterns by medium-energy ion beam sputtering (IBS) of silicon targets with a simultaneous and isotropic molybdenum supply. Atomic force microscopy (AFM) studies show that these patterns are qualitatively similar to those produced thus far at low ion energies. We have determined the relevance of the ion species on the pattern ordering and properties. For the higher ordered patterns produced by Xe+ ions, the pattern wavelength depends linearly on the ion energy. The dot nanostructures are silicide-rich as assessed by x-ray photoelectron spectroscopy (XPS) and emerge in height due to their lower sputtering yield, as observed by electron microscopy. Remarkably, a long wavelength corrugation is observed on the surface which is correlated with both the Mo content and the dot pattern properties. Thus, as assessed by electron microscopy, the protrusions are Mo-rich with higher and more spaced dots on their surface whereas the valleys are Mo-poor with smaller dots that are closer to each other. These findings indicate that there is a correlation between the local metal content of the surface and the nanodot pattern properties both at the nanodot and the large corrugation scales. These results contribute to advancing the understanding of this interesting nanofabrication method and aid in developing a comprehensive theory of nanodot pattern formation and evolution.

  14. Severity and pattern of bone mineral loss in endocrine causes of osteoporosis as compared to age-related bone mineral loss

    Directory of Open Access Journals (Sweden)

    D Dutta

    2016-01-01

    Full Text Available Background: Data are scant on bone health in endocrinopathies from India. This study evaluated bone mineral density (BMD loss in endocrinopathies [Graves′ disease (GD, type 1 diabetes mellitus (T1DM, hypogonadotrophic hypogonadism (HypoH, hypergonadotropic hypogonadism (HyperH, hypopituitarism, primary hyperparathyroidism (PHPT] as compared to age-related BMD loss [postmenopausal osteoporosis (PMO, andropause]. Materials and Methods: Retrospective audit of records of patients >30 years age attending a bone clinic from August 2014 to January 2016 was done. Results: Five-hundred and seven records were screened, out of which 420 (females:male = 294:126 were analyzed. A significantly higher occurrence of vitamin D deficiency and insufficiency was noted in T1DM (89.09%, HyperH (85%, and HypoH (79.59% compared to age-related BMD loss (60.02%; P < 0.001. The occurrence of osteoporosis among females and males was 55.41% and 53.97%, respectively, and of osteopenia among females and males was 28.91% and 32.54%, respectively. In females, osteoporosis was significantly higher in T1DM (92%, HyperH (85%, and HypoH (59.26% compared to PMO (49.34%; P < 0.001. Z score at LS, TF, NOF, and greater trochanter (GT was consistently lowest in T1DM women. Among men, osteoporosis was significantly higher in T1DM (76.67% and HypoH (54.55% compared to andropause (45.45%; P = 0.001. Z score at LS, TF, NOF, GT, and TR was consistently lowest in T1DM men. In GD, the burden of osteoporosis was similar to PMO and andropause. BMD difference among the study groups was not significantly different after adjusting for body mass index (BMI and vitamin D. Conclusion: Low bone mass is extremely common in endocrinopathies, warranting routine screening and intervention. Concomitant vitamin D deficiency compounds the problem. Calcium and vitamin D supplementations may improve bone health in this setting.

  15. Monitoring Dosimetric Impact of Weight Loss With Kilovoltage (KV) Cone Beam CT (CBCT) During Parotid-Sparing IMRT and Concurrent Chemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Kean Fatt, E-mail: hokeanfatt@hotmail.com [Academic Radiation Oncology, The Christie NHS Foundation Trust, Manchester (United Kingdom); Marchant, Tom; Moore, Chris; Webster, Gareth; Rowbottom, Carl [North Western Medical Physics, The Christie NHS Foundation Trust, Manchester (United Kingdom); Penington, Hazel [Wade Radiotherapy Research Centre, The Christie NHS Foundation Trust, Manchester (United Kingdom); Lee, Lip; Yap, Beng; Sykes, Andrew; Slevin, Nick [Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester (United Kingdom)

    2012-03-01

    Purpose: Parotid-sparing head-and-neck intensity-modulated radiotherapy (IMRT) can reduce long-term xerostomia. However, patients frequently experience weight loss and tumor shrinkage during treatment. We evaluate the use of kilovoltage (kV) cone beam computed tomography (CBCT) for dose monitoring and examine if the dosimetric impact of such changes on the parotid and critical neural structures warrants replanning during treatment. Methods and materials: Ten patients with locally advanced oropharyngeal cancer were treated with contralateral parotid-sparing IMRT concurrently with platinum-based chemotherapy. Mean doses of 65 Gy and 54 Gy were delivered to clinical target volume (CTV)1 and CTV2, respectively, in 30 daily fractions. CBCT was prospectively acquired weekly. Each CBCT was coregistered with the planned isocenter. The spinal cord, brainstem, parotids, larynx, and oral cavity were outlined on each CBCT. Dose distributions were recalculated on the CBCT after correcting the gray scale to provide accurate Hounsfield calibration, using the original IMRT plan configuration. Results: Planned contralateral parotid mean doses were not significantly different to those delivered during treatment (p > 0.1). Ipsilateral and contralateral parotids showed a mean reduction in volume of 29.7% and 28.4%, respectively. There was no significant difference between planned and delivered maximum dose to the brainstem (p = 0.6) or spinal cord (p = 0.2), mean dose to larynx (p = 0.5) and oral cavity (p = 0.8). End-of-treatment mean weight loss was 7.5 kg (8.8% of baseline weight). Despite a {>=}10% weight loss in 5 patients, there was no significant dosimetric change affecting the contralateral parotid and neural structures. Conclusions: Although patient weight loss and parotid volume shrinkage was observed, overall, there was no significant excess dose to the organs at risk. No replanning was felt necessary for this patient cohort, but a larger patient sample will be investigated

  16. Margin selection to compensate for loss of target dose coverage due to target motion during external-beam radiation therapy of the lung.

    Science.gov (United States)

    Foster, W Kyle; Osei, Ernest; Barnett, Rob

    2015-01-08

    The aim of this study is to provide guidelines for the selection of external-beam radiation therapy target margins to compensate for target motion in the lung during treatment planning. A convolution model was employed to predict the effect of target motion on the delivered dose distribution. The accuracy of the model was confirmed with radiochromic film measurements in both static and dynamic phantom modes. 502 unique patient breathing traces were recorded and used to simulate the effect of target motion on a dose distribution. A 1D probability density function (PDF) representing the position of the target throughout the breathing cycle was generated from each breathing trace obtained during 4D CT. Changes in the target D95 (the minimum dose received by 95% of the treatment target) due to target motion were analyzed and shown to correlate with the standard deviation of the PDF. Furthermore, the amount of target D95 recovered per millimeter of increased field width was also shown to correlate with the standard deviation of the PDF. The sensitivity of changes in dose coverage with respect to target size was also determined. Margin selection recommendations that can be used to compensate for loss of target D95 were generated based on the simulation results. These results are discussed in the context of clinical plans. We conclude that, for PDF standard deviations less than 0.4 cm with target sizes greater than 5 cm, little or no additional margins are required. Targets which are smaller than 5 cm with PDF standard deviations larger than 0.4 cm are most susceptible to loss of coverage. The largest additional required margin in this study was determined to be 8 mm.

  17. High-resolution, high-throughput, positive-tone patterning of poly(ethylene glycol by helium beam exposure through stencil masks.

    Directory of Open Access Journals (Sweden)

    Eliedonna E Cacao

    Full Text Available In this work, a collimated helium beam was used to activate a thiol-poly(ethylene glycol (SH-PEG monolayer on gold to selectively capture proteins in the exposed regions. Protein patterns were formed at high throughput by exposing a stencil mask placed in proximity to the PEG-coated surface to a broad beam of helium particles, followed by incubation in a protein solution. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR spectra showed that SH-PEG molecules remain attached to gold after exposure to beam doses of 1.5-60 µC/cm(2 and incubation in PBS buffer for one hour, as evidenced by the presence of characteristic ether and methoxy peaks at 1120 cm(-1 and 2870 cm(-1, respectively. X-ray Photoelectron Spectroscopy (XPS spectra showed that increasing beam doses destroy ether (C-O bonds in PEG molecules as evidenced by the decrease in carbon C1s peak at 286.6 eV and increased alkyl (C-C signal at 284.6 eV. XPS spectra also demonstrated protein capture on beam-exposed PEG regions through the appearance of a nitrogen N1s peak at 400 eV and carbon C1s peak at 288 eV binding energies, while the unexposed PEG areas remained protein-free. The characteristic activities of avidin and horseradish peroxidase were preserved after attachment on beam-exposed regions. Protein patterns created using a 35 µm mesh mask were visualized by localized formation of insoluble diformazan precipitates by alkaline phosphatase conversion of its substrate bromochloroindoyl phosphate-nitroblue tetrazolium (BCIP-NBT and by avidin binding of biotinylated antibodies conjugated on 100 nm gold nanoparticles (AuNP. Patterns created using a mask with smaller 300 nm openings were detected by specific binding of 40 nm AuNP probes and by localized HRP-mediated deposition of silver nanoparticles. Corresponding BSA-passivated negative controls showed very few bound AuNP probes and little to no enzymatic formation of diformazan precipitates or silver

  18. The role of phase separation for self-organized surface pattern formation by ion beam erosion and metal atom co-deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hofsaess, H.; Zhang, K.; Pape, A.; Bobes, O.; Broetzmann, M. [Georg-August University Goettingen, II. Institute of Physics, Goettingen (Germany)

    2013-05-15

    We investigate the ripple pattern formation on Si surfaces at room temperature during normal incidence ion beam erosion under simultaneous deposition of different metallic co-deposited surfactant atoms. The co-deposition of small amounts of metallic atoms, in particular Fe and Mo, is known to have a tremendous impact on the evolution of nanoscale surface patterns on Si. In previous work on ion erosion of Si during co-deposition of Fe atoms, we proposed that chemical interactions between Fe and Si atoms of the steady-state mixed Fe{sub x} Si surface layer formed during ion beam erosion is a dominant driving force for self-organized pattern formation. In particular, we provided experimental evidence for the formation of amorphous iron disilicide. To confirm and generalize such chemical effects on the pattern formation, in particular the tendency for phase separation, we have now irradiated Si surfaces with normal incidence 5 keV Xe ions under simultaneous gracing incidence co-deposition of Fe, Ni, Cu, Mo, W, Pt, and Au surfactant atoms. The selected metals in the two groups (Fe, Ni, Cu) and (W, Pt, Au) are very similar regarding their collision cascade behavior, but strongly differ regarding their tendency to silicide formation. We find pronounced ripple pattern formation only for those co deposited metals (Fe, Mo, Ni, W, and Pt), which are prone to the formation of mono and disilicides. In contrast, for Cu and Au co-deposition the surface remains very flat, even after irradiation at high ion fluence. Because of the very different behavior of Cu compared to Fe, Ni and Au compared to W, Pt, phase separation toward amorphous metal silicide phases is seen as the relevant process for the pattern formation on Si in the case of Fe, Mo, Ni, W, and Pt co-deposition. (orig.)

  19. Height loss with advancing age in a hospitalized population of Polish men and women: magnitude, pattern and associations with mortality

    Directory of Open Access Journals (Sweden)

    Chmielewski Piotr

    2015-06-01

    Full Text Available The connection between the rate of height loss in older people and their general health status has been well documented in the medical literature. Our study was aimed at furthering the characterization of this interrelationship in the context of health indices and mortality in a hospitalized population of Polish adults. Data were collated from a literature review and from a longitudinal study of aging carried out in the Polish population which followed 142 physically healthy inmates, including 68 men and 74 women, for at least 25 years from the age of 45 onwards. Moreover, cross-sectional data were available from 225 inmates, including 113 men and 112 women. These subjects were confined at the same hospital. ANOVA, t-test, and regression analysis were employed. The results indicate that the onset of height loss emerges in the fourth and five decade of life and there is a gradual acceleration of reduction of height at later stages of ontogeny in both sexes. Postmenopausal women experience a more rapid loss of height compared with men. The individuals who had higher rate of loss of height (≥3 cm/decade tend to be at greater risk of cardiovascular events and all-cause mortality. In conclusion, our findings suggest that a systematic assessment of the rate of loss of height can be useful for clinicians caring for elderly people because of its prognostic value in terms of morbidity and mortality.

  20. Investigation of fabrication process for sub 20-nm dense pattern of non-chemically amplified electron beam resist based on acrylic polymers

    Science.gov (United States)

    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.

  1. Diffraction pattern by nanometric thin films under illumination of an orbital angular momentum beam with integer topological charge

    Science.gov (United States)

    Mendoza, J. H.; Díaz, C. F.; Acevedo, C. H.; Torres, Y.

    2016-02-01

    The orbital angular momentum of light has a big contribution in many engineering applications like optical communications, because this physical property allows eigenstates characteristic of the wavefront rotation when the beam is propagated. The nature of these eigenstates allows that information can be encoded and gives immunity to electromagnetic interference, allowing an increase of bandwidth, cadence and capacity of the communication channel. This work shown the methodology using nanometric thin films like Titanium based (TiO2) grown over strontium titanate (SrTiO3) support, to distinguish and discriminate a well- defined integer value of the topological charge of an OAM beam.

  2. 贝塞尔高斯光束通过硬边光阑的衍射损耗%Losses of Bessel-Gaussian Beams Propagating through a Hard-Edge Aperture

    Institute of Scientific and Technical Information of China (English)

    王莉

    2001-01-01

    The losses Bessel-Gaussian beams, a kind of non-diffracting beam,propagating through a hard aperture are studied, and a general formula is derived. As an example of applications, numerical calculation is performed to calculate the losses of Bessel-Gaussian beams propagating through a circular aperture. The obtained results are analyzed and discussed. The proposed method can also be applied to calculation of the losses of other types of laser beams propagating through a hard-edge aperture.%对无衍射光束——贝塞尔高斯光束通过硬边光阑时的功率损耗作了研究,给出了普适的损耗公式。作为应用举例,对零阶贝塞尔高斯光束通过圆孔硬边光阑时的衍射损耗作了详细的计算。对计算结果进行了分析和讨论。该方法还可用于其它光束通过硬边光阑的衍射损耗计算。

  3. Habitual physical activity and plasma metabolomic patterns distinguish individuals with low vs. high weight loss during controlled energy restriction

    Science.gov (United States)

    Weight loss (WL) induced by energy restriction is highly variable even in controlled clinical trials. An integrative analysis of the plasma metabolome coupled to traditional clinical variables may reveal a WL “responder” phenotype. Therfore, we predicted WL in overweight and obese individuals on a...

  4. Stress evaluation in thin films: Micro-focus synchrotron X-ray diffraction combined with focused ion beam patterning for d{sub o} evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Baimpas, Nikolaos, E-mail: nikolaos.baimpas@eng.ox.ac.uk [University of Oxford, Dept. of Engineering Science (United Kingdom); Le Bourhis, Eric [University of Poitiers, Institut P' , Laboratoire de Physique des Matériaux, Poitiers (France); Eve, Sophie [ENSICAEN, CRISMAT, Caen (France); Thiaudière, Dominique [Synchrotron SOLEIL, L' Orme des Merisiers Saint-Aubin, Paris (France); Hardie, Christopher [University of Oxford, Materials Department (United Kingdom); Korsunsky, Alexander M. [University of Oxford, Dept. of Engineering Science (United Kingdom)

    2013-12-31

    Nanocrystalline metallic coatings of sub-micron thickness are widely used in modern microelectronic applications. In X-ray diffraction experiments to determine both the residual and applied stresses in nanocrystalline coatings, one difficult challenge that comes up invariably is the determination of the strain-free lattice spacing d{sub o}. The present study addresses this challenge by using the focused ion beam (FIB) to generate a built-in strain-free reference by patterning (milling) a 50 × 50 μm{sup 2} region of the coating to produce an array of small stress-relieved “islands” ∼ 0.8 × 0.8 μm{sup 2} each. Transmission X-ray diffraction setup was used for data collection at DIFFABS beamline (Synchrotron SOLEIL, France). A 150 nm-thick multi-layered W–Cu nano-composite thin film on polyimide (Kapton®) substrate was studied. The samples were loaded incrementally using a compact uniaxial loading device, and micro-beam diffraction data were collected on and away from the reference array. It was shown experimentally that the “island” array remained approximately strain free throughout the experiment, providing an on-board d{sub o} lattice spacing reference. The changing lattice spacing d in the coating was also monitored away from the array, to deduce the elastic strain evolution during deformation. The results and their implications are presented and discussed. - Highlights: • In situ deformation study of laminate polycrystalline W–Cu thin films • Focused ion beam (FIB) patterning of an array of “islands” on thin films surface • X-ray diffraction on island-patterned region • Constant strain on “islands” independently of the deformation of the substrate.

  5. Small phase pattern 2D beam steering and a single LCOS design of 40 1 × 12 stacked wavelength selective switches.

    Science.gov (United States)

    Yang, Haining; Robertson, Brian; Wilkinson, Peter; Chu, Daping

    2016-05-30

    Two-dimensional beam steering by small, square, phase patterns as small as 50 × 50 pixels on a phase-only liquid crystal on silicon (LCOS) device is experimentally verified as suitable for the application of wavelength selective switches (WSSs), in terms of the diffraction efficiency and steering accuracy. This enables a proposed highly functional and versatile stacked switch architecture, where 40 independent 1 × 12 WSSs can be realised on a single 4k LCOS device. They can be configured to support a 1 × N WSSs with N≤144, or an N × N wavelength crossconnect with N≤12.

  6. Evaluation of opening pattern and bone neoformation at median palatal suture area in patients submitted to surgically assisted rapid maxillary expansion (SARME through cone beam computed tomography

    Directory of Open Access Journals (Sweden)

    Daniel Gomes SALGUEIRO

    2015-08-01

    Full Text Available AbstractSurgically assisted rapid maxillary expansion (SARME is the treatment of choice to adult patients even with severe transversal maxillary discrepancies. However, the adequate retention period to achieve the bone remodeling, thus assuring treatment stability, is controversial.Objective To evaluate the opening pattern and bone neoformation process at the midpalatal suture in patients submitted to surgically assisted (SARME through cone beam computed tomography (CBCT.Material and Methods Fourteen patients were submitted to SARME through subtotal Le Fort I osteotomy. Both the opening pattern and the mean bone density at midpalatal suture area to evaluate bone formation were assessed pre- and post-operatively (15, 60 and 180 days through CBCT.Results Type I opening pattern (from anterior to posterior nasal spine occurred in 12 subjects while type II opening pattern (from anterior nasal spine to transverse palatine suture occurred in 2 individuals. The 180-day postoperative mean (PO 180 of bone density value was 49.9% of the preoperative mean (Pre value.Conclusions The opening pattern of midpalatal suture is more related to patients’ age (23.9 years in type I and 33.5 years in type II and surgical technique. It was not possible to observe complete bone formation at midpalatal suture area at the ending of the retention period studied (180 days.

  7. Loss of ATRX, associated with DNA methylation pattern of chromosome end, impacted biological behaviors of astrocytic tumors

    OpenAIRE

    CAI, JINQUAN; Chen, Jing; Zhang, Wei; Yang, Pei; Zhang, Chuanbao; Li, Mingyang; Yao, Kun; Wang, Hongjun; Li, Qingbin; Jiang, Chuanlu; Jiang., Tao

    2015-01-01

    Loss of ATRX leads to epigenetic alterations, including abnormal levels of DNA methylation at repetitive elements such as telomeres in murine cells. We conducted an extensive DNA methylation and mRNA expression profile study on a cohort of 82 patients with astrocytic tumors to study whether ATRX expression was associated with DNA methylation level in astrocytic tumors and in which cellular functions it participated. We observed that astrocytic tumors with lower ATRX expression harbored higher...

  8. Loss of ATRX, associated with DNA methylation pattern of chromosome end, impacted biological behaviors of astrocytic tumors.

    Science.gov (United States)

    Cai, Jinquan; Chen, Jing; Zhang, Wei; Yang, Pei; Zhang, Chuanbao; Li, Mingyang; Yao, Kun; Wang, Hongjun; Li, Qingbin; Jiang, Chuanlu; Jiang, Tao

    2015-07-20

    Loss of ATRX leads to epigenetic alterations, including abnormal levels of DNA methylation at repetitive elements such as telomeres in murine cells. We conducted an extensive DNA methylation and mRNA expression profile study on a cohort of 82 patients with astrocytic tumors to study whether ATRX expression was associated with DNA methylation level in astrocytic tumors and in which cellular functions it participated. We observed that astrocytic tumors with lower ATRX expression harbored higher DNA methylation level at chromatin end and astrocytic tumors with ATRX-low had distinct gene expression profile and DNA methylation profile compared with ATRX-high tumors. Then, we uncovered that several ATRX associated biological functions in the DNA methylation and mRNA expression profile (GEP), including apoptotic process, DNA-dependent positive regulation of transcription, chromatin modification, and observed that ATRX expression was companied by MGMT methylation and expression. We also found that loss of ATRX caused by siRNA induced apoptotic cells increasing, reduced tumor cell proliferation and repressed the cell migration in glioma cells. Our results showed ATRX-related regulatory functions of the combined profiles from DNA methylation and mRNA expression in astrocytic tumors, and delineated that loss of ATRX impacted biological behaviors of astrocytic tumor cells, providing important resources for future dissection of ATRX role in glioma.

  9. Lateralized loss of biting attack-patterned reflexes following induction of contralateral sensory neglect in the cat: a possible role for the striatum in centrally elicited aggressive behaviour.

    Science.gov (United States)

    Bandler, R; Halliday, R

    1982-06-17

    A syndrome of "contralateral sensory neglect' was induced by hypothalamic knife cuts in 6 of 10 cats in which quiet biting attack behaviour could be elicited by lateral hypothalamic stimulation. The contralateral sensory neglect in the 6 affected cats was accompanied by a loss on the "neglected' side of the body of the patterned reflexes which mediate positioning of the head to bite and the jaw-opening component of biting. As a result, when these cats were stimulated in the lateral hypothalamus, although they continued to approach and even make tactile contact with the rat, they generally failed to bite it. Analysis of the histological and behavioural data suggested that damage to the nigrostriatal and/or striato/pallidonigral fibre systems provided the likely basis for both the induction of the contralateral sensory neglect and the lateralized patterned reflex loss. It was suggested, with respect to these specific patterned reflex components of the attack, that an important contribution may be made by the striatum.

  10. Patterned growth of InGaN/GaN quantum wells on freestanding GaN grating by molecular beam epitaxy

    Directory of Open Access Journals (Sweden)

    Wang Yongjin

    2011-01-01

    Full Text Available Abstract We report here the epitaxial growth of InGaN/GaN quantum wells on freestanding GaN gratings by molecular beam epitaxy (MBE. Various GaN gratings are defined by electron beam lithography and realized on GaN-on-silicon substrate by fast atom beam etching. Silicon substrate beneath GaN grating region is removed from the backside to form freestanding GaN gratings, and the patterned growth is subsequently performed on the prepared GaN template by MBE. The selective growth takes place with the assistance of nanoscale GaN gratings and depends on the grating period P and the grating width W. Importantly, coalescences between two side facets are realized to generate epitaxial gratings with triangular section. Thin epitaxial gratings produce the promising photoluminescence performance. This work provides a feasible way for further GaN-based integrated optics devices by a combination of GaN micromachining and epitaxial growth on a GaN-on-silicon substrate. PACS 81.05.Ea; 81.65.Cf; 81.15.Hi.

  11. Linear energy transfer and track pattern recognition of secondary radiation generated in hadron therapy beam in a PMMA target

    Science.gov (United States)

    Opalka, L.; Granja, C.; Hartmann, B.; Jakubek, J.; Jaekel, O.; Martisikova, M.; Pospisil, S.; Solc, J.

    2013-02-01

    Hadron therapy uses ion beams for irradiation of cancerous tissue taking advantage of the highly localized dose deposition in the target tumor. For a correct estimation of dose deposited in tissue surrounding the target it is necessary to consider also the contribution of energetic secondary radiation generated by primary ions. It was already experimentally demonstrated that this contribution can be measured using the semiconductor pixel detector Timepix (256 × 256 pixels with 55 μm pitch) visualizing traces of secondary particles. The resolving power of the detector enables the differentiation of traces of different types of particles. In this work we studied the possibilities of determination of different types of secondary particles in correlation with their flight direction. Such identification allows correct assignment of dose for each type of particle. The distribution of secondary particles was compared to Monte Carlo simulations. Measurements were performed with a PMMA target irradiated with a therapeutic carbon beam at the Heidelberg Ion-Beam Therapy Center (HIT).

  12. Specific Diurnal EMG Activity Pattern Observed in Occlusal Collapse Patients: Relationship between Diurnal Bruxism and Tooth Loss Progression

    Science.gov (United States)

    Kawakami, Shigehisa; Kumazaki, Yohei; Manda, Yosuke; Oki, Kazuhiro; Minagi, Shogo

    2014-01-01

    Aim The role of parafunctional masticatory muscle activity in tooth loss has not been fully clarified. This study aimed to reveal the characteristic activity of masseter muscles in bite collapse patients while awake and asleep. Materials and Methods Six progressive bite collapse patients (PBC group), six age- and gender-matched control subjects (MC group), and six young control subjects (YC group) were enrolled. Electromyograms (EMG) of the masseter muscles were continuously recorded with an ambulatory EMG recorder while patients were awake and asleep. Diurnal and nocturnal parafunctional EMG activity was classified as phasic, tonic, or mixed using an EMG threshold of 20% maximal voluntary clenching. Results Highly extended diurnal phasic activity was observed only in the PBC group. The three groups had significantly different mean diurnal phasic episodes per hour, with 13.29±7.18 per hour in the PBC group, 0.95±0.97 per hour in the MC group, and 0.87±0.98 per hour in the YC group (p<0.01). ROC curve analysis suggested that the number of diurnal phasic episodes might be used to predict bite collapsing tooth loss. Conclusion Extensive bite loss might be related to diurnal masticatory muscle parafunction but not to parafunction during sleep. Clinical Relevance: Scientific rationale for study Although mandibular parafunction has been implicated in stomatognathic system breakdown, a causal relationship has not been established because scientific modalities to evaluate parafunctional activity have been lacking. Principal findings This study used a newly developed EMG recording system that evaluates masseter muscle activity throughout the day. Our results challenge the stereotypical idea of nocturnal bruxism as a strong destructive force. We found that diurnal phasic masticatory muscle activity was most characteristic in patients with progressive bite collapse. Practical implications The incidence of diurnal phasic contractions could be used for the prognostic

  13. Specific diurnal EMG activity pattern observed in occlusal collapse patients: relationship between diurnal bruxism and tooth loss progression.

    Directory of Open Access Journals (Sweden)

    Shigehisa Kawakami

    Full Text Available AIM: The role of parafunctional masticatory muscle activity in tooth loss has not been fully clarified. This study aimed to reveal the characteristic activity of masseter muscles in bite collapse patients while awake and asleep. MATERIALS AND METHODS: Six progressive bite collapse patients (PBC group, six age- and gender-matched control subjects (MC group, and six young control subjects (YC group were enrolled. Electromyograms (EMG of the masseter muscles were continuously recorded with an ambulatory EMG recorder while patients were awake and asleep. Diurnal and nocturnal parafunctional EMG activity was classified as phasic, tonic, or mixed using an EMG threshold of 20% maximal voluntary clenching. RESULTS: Highly extended diurnal phasic activity was observed only in the PBC group. The three groups had significantly different mean diurnal phasic episodes per hour, with 13.29±7.18 per hour in the PBC group, 0.95±0.97 per hour in the MC group, and 0.87±0.98 per hour in the YC group (p<0.01. ROC curve analysis suggested that the number of diurnal phasic episodes might be used to predict bite collapsing tooth loss. CONCLUSION: Extensive bite loss might be related to diurnal masticatory muscle parafunction but not to parafunction during sleep. CLINICAL RELEVANCE SCIENTIFIC RATIONALE FOR STUDY: Although mandibular parafunction has been implicated in stomatognathic system breakdown, a causal relationship has not been established because scientific modalities to evaluate parafunctional activity have been lacking. PRINCIPAL FINDINGS: This study used a newly developed EMG recording system that evaluates masseter muscle activity throughout the day. Our results challenge the stereotypical idea of nocturnal bruxism as a strong destructive force. We found that diurnal phasic masticatory muscle activity was most characteristic in patients with progressive bite collapse. PRACTICAL IMPLICATIONS: The incidence of diurnal phasic contractions could be used for

  14. Pattern transfer from the e-beam resist, over the nanoimprint resist and to the final silicon substrate

    Science.gov (United States)

    He, Jian; Howitz, S.; Richter, K.; Bartha, J. W.; Moench, J. I.

    2012-03-01

    We developed Fluor-based RIE processes to fabricate nanoimprint template in silicon and to transfer patterns from the imprint resist to the silicon substrate. The etched silicon patterns have slightly tapered and smooth sidewalls. The sidewall angle can be controlled between 85° and 90° by varying the ratio of the used gas. The dimension of the etched structures is identical with the patterns in the resist. We demonstrated line structures in silicon substrate down to 50 nm. The etching rate is over 100 nm per minute and the maximal achieved aspect ratio is more than 10.

  15. Propagation Properties of Dark Hollow Beams in Linear Gain and Loss Media%空心光束在损耗和增益介质中的传输特性

    Institute of Scientific and Technical Information of China (English)

    朱焯炜; 赵琳琳; 苏宙平

    2011-01-01

    Based on the definition of complex wave number and the generalized Huygens-Fresnel diffraction integral,the closed-form propagation equation of Dark hollow beams passing through a paraxial optical ABCD system is derived. The beam-width propagation formula of Dark hollow beams through absorption media are obtained on the basis of the second-order moment method. By numerical analysis,the intensity distributions and beams waist width have been studied. The results show that, the dark hollow beams propagation in linear gain or loss media,when the media property is gain (loss) ,it will heighten (lower) the intensity;but it has little effect on the beams waist width.%从复数波数定义和广义惠更斯-菲涅尔积分出发,推导出空心光束在介质中通过旁轴ABCD光学系统后的一般传输公式.在此基础上,结合光强二阶矩方法,给出了相应的一般束宽变换公式.通过数值分析研究了介质传输场中强度分布和均方根束宽的变化特点.研究结果表明,空心光束在增益或者损耗介质中传输时,当其为增益(损耗)介质时,会增强(衰减)光束的强度;但对均方根束宽却没有太大的影响.

  16. Analog Front End Circuit Design of CSNS Beam Loss Monitor System%CSNS 束流损失监测系统前端模拟电路设计

    Institute of Scientific and Technical Information of China (English)

    肖帅; 郭娴; 田建民; 曾磊; 徐韬光; 傅世年

    2013-01-01

    中国散裂中子源(CSNS)束流损失监测系统利用气体电离室来探测束流损失,电离室输出信号需在前端模拟电路中进行信号处理。本工作自主设计开发了束流损失测量系统前端模拟电路,采用跨导放大的方式实现了低重复频率、低占空比、弱电离室信号的电流-电压(I-V )变换测量。同时,电路还实现了对较大束流损失的快速响应,保障加速器设备的安全运行。联机测试结果表明,该电路满足系统要求。%The China Spallation Neutron Source (CSNS) beam loss monitor system uses gas ionization chamber to detect beam losses . The output signals from ionization chamber need to be processed in the analog front end circuit ,which has been designed and developed independently .The way of transimpedance amplifier was used to achieve current-voltage (I-V ) conversion measurement of signal with low repetition rate ,low duty cycle and low amplitude .The analog front end circuit also realized rapid response to the larger beam loss in order to protect the safe operation of the accelerator equipment . The testing results show that the analog front end circuit meets the requirements of beam loss monitor system .

  17. Self-catalyzed ternary core-shell GaAsP nanowire arrays grown on patterned Si substrates by molecular beam epitaxy.

    Science.gov (United States)

    Zhang, Yunyan; Wu, Jiang; Aagesen, Martin; Holm, Jeppe; Hatch, Sabina; Tang, Mingchu; Huo, Suguo; Liu, Huiyun

    2014-08-13

    The growth of self-catalyzed ternary core-shell GaAsP nanowire (NW) arrays on SiO2 patterned Si(111) substrates has been demonstrated by using solid-source molecular beam epitaxy. A high-temperature deoxidization step up to ∼ 900 °C prior to NW growth was used to remove the native oxide and/or SiO2 residue from the patterned holes. To initiate the growth of GaAsP NW arrays, the Ga predeposition used for assisting the formation of Ga droplets in the patterned holes, was shown to be another essential step. The effects of the patterned-hole size on the NW morphology were also studied and explained using a simple growth model. A lattice-matched radial GaAsP core-shell NW structure has subsequently been developed with room-temperature photoluminescence emission around 740 nm. These results open up new perspectives for integrating position-controlled III-V NW photonic and electronic structures on a Si platform.

  18. Graphene crystal growth by thermal precipitation of focused ion beam induced deposition of carbon precursor via patterned-iron thin layers

    Directory of Open Access Journals (Sweden)

    Rius Gemma

    2014-01-01

    Full Text Available Recently, relevant advances on graphene as a building block of integrated circuits (ICs have been demonstrated. Graphene growth and device fabrication related processing has been steadily and intensively powered due to commercial interest; however, there are many challenges associated with the incorporation of graphene into commercial applications which includes challenges associated with the synthesis of this material. Specifically, the controlled deposition of single layer large single crystal graphene on arbitrary supports, is particularly challenging. Previously, we have reported the first demonstration of the transformation of focused ion beam induced deposition of carbon (FIBID-C into patterned graphitic layers by metal-assisted thermal treatment (Ni foils. In this present work, we continue exploiting the FIBID-C approach as a route for graphene deposition. Here, thin patterned Fe layers are used for the catalysis of graphenization and graphitization. We demonstrate the formation of high quality single and few layer graphene, which evidences, the possibility of using Fe as a catalyst for graphene deposition. The mechanism is understood as the minute precipitation of atomic carbon after supersaturation of some iron carbides formed under a high temperature treatment. As a consequence of the complete wetting of FIBID-C and patterned Fe layers, which enable graphene growth, the as-deposited patterns do not preserve their original shape after the thermal treatment

  19. Tandem Mass Spectrometry of Heparan Sulfate Negative Ions: Sulfate Loss Patterns and Chemical Modification Methods for Improvement of Product Ion Profiles

    Science.gov (United States)

    Shi, Xiaofeng; Huang, Yu; Mao, Yang; Naimy, Hicham; Zaia, Joseph

    2012-09-01

    Heparan sulfate (HS) is a polysaccharide modified with sulfation, acetylation, and epimerization that enable its binding with protein ligands and regulation of important biological processes. Tandem mass spectrometry has been employed to sequence linear biomolecules e.g., proteins and peptides. However, its application in structural characterization of HS is limited due to the neutral loss of sulfate (SO3) during collisional induced dissociation (CID). In this report, we studied the dissociation patterns of HS disaccharides and demonstrate that the N-sulfate (N-S) bond is especially facile during CID. We identified factors that influence the propensities of such losses from precursor ions and proposed a Free Proton Index (FPI) to help select ions that are able to produce meaningful backbone dissociations. We then investigated the thermodynamics and kinetics of SO3 loss from sulfates that are protonated, deprotonated, and metal-adducted using density functional theory computations. The calculations showed that sulfate loss from a protonated site was much more facile than that from a deprotonated or metal-adducted site. Further, the loss of SO3 from N-sulfate was energetically favored by 3-8 kcal/mol in transition states relative to O-sulfates, making it more prone to this process by a substantial factor. In order to reduce the FPI, representing the number of labile sulfates in HS native chains and oligosaccharides, we developed a series of chemical modifications to selectively replace the N-sulfates of the glucosamine with deuterated acetyl group. These modifications effectively reduced the sulfate density on the HS oligosaccharides and generated considerably more backbone dissociation using on-line LC/tandem MS.

  20. Comparison of interradicular distances and cortical bone thickness in Thai patients with Class I and Class II skeletal patterns using cone-beam computed tomography

    Science.gov (United States)

    Khumsarn, Nattida; Patanaporn, Virush; Jotikasthira, Dhirawat

    2016-01-01

    Purpose This study evaluated and compared interradicular distances and cortical bone thickness in Thai patients with Class I and Class II skeletal patterns, using cone-beam computed tomography (CBCT). Materials and Methods Pretreatment CBCT images of 24 Thai orthodontic patients with Class I and Class II skeletal patterns were included in the study. Three measurements were chosen for investigation: the mesiodistal distance between the roots, the width of the buccolingual alveolar process, and buccal cortical bone thickness. All distances were recorded at five different levels from the cementoenamel junction (CEJ). Descriptive statistical analysis and t-tests were performed, with the significance level for all tests set at p<0.05. Results Patients with a Class II skeletal pattern showed significantly greater maxillary mesiodistal distances (between the first and second premolars) and widths of the buccolingual alveolar process (between the first and second molars) than Class I skeletal pattern patients at 10 mm above the CEJ. The maxillary buccal cortical bone thicknesses between the second premolar and first molar at 8 mm above the CEJ in Class II patients were likewise significantly greater than in Class I patients. Patients with a Class I skeletal pattern showed significantly wider mandibular buccolingual alveolar processes than did Class II patients (between the first and second molars) at 4, 6, and 8 mm below the CEJ. Conclusion In both the maxilla and mandible, the mesiodistal distances, the width of the buccolingual alveolar process, and buccal cortical bone thickness tended to increase from the CEJ to the apex in both Class I and Class II skeletal patterns. PMID:27358819

  1. Comparison of interradicular distances and cortical bone thickness in Thai patients with class I and class II skeletal patterns using cone-beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Khumsarn, Nattida [Dental Division of Lamphun Hospital, Lamphun (Thailand); Patanaporn, Virush; Janhom, Apirum; Jotikasthira, Dhirawat [Faculty of Dentistry, Chiang Mai University, Chiang Mai (Thailand)

    2016-06-15

    This study evaluated and compared interradicular distances and cortical bone thickness in Thai patients with Class I and Class II skeletal patterns, using cone-beam computed tomography (CBCT). Pretreatment CBCT images of 24 Thai orthodontic patients with Class I and Class II skeletal patterns were included in the study. Three measurements were chosen for investigation: the mesiodistal distance between the roots, the width of the buccolingual alveolar process, and buccal cortical bone thickness. All distances were recorded at five different levels from the cementoenamel junction (CEJ). Descriptive statistical analysis and t-tests were performed, with the significance level for all tests set at p<0.05. Patients with a Class II skeletal pattern showed significantly greater maxillary mesiodistal distances (between the first and second premolars) and widths of the buccolingual alveolar process (between the first and second molars) than Class I skeletal pattern patients at 10 mm above the CEJ. The maxillary buccal cortical bone thicknesses between the second premolar and first molar at 8 mm above the CEJ in Class II patients were likewise significantly greater than in Class I patients. Patients with a Class I skeletal pattern showed significantly wider mandibular buccolingual alveolar processes than did Class II patients (between the first and second molars) at 4, 6, and 8 mm below the CEJ. In both the maxilla and mandible, the mesiodistal distances, the width of the buccolingual alveolar process, and buccal cortical bone thickness tended to increase from the CEJ to the apex in both Class I and Class II skeletal patterns.

  2. Resistance of virus to extinction on bottleneck passages: Study of a decaying and fluctuating pattern of fitness loss

    Science.gov (United States)

    Lázaro, Ester; Escarmís, Cristina; Pérez-Mercader, Juan; Manrubia, Susanna C.; Domingo, Esteban

    2003-01-01

    RNA viruses display high mutation rates and their populations replicate as dynamic and complex mutant distributions, termed viral quasispecies. Repeated genetic bottlenecks, which experimentally are carried out through serial plaque-to-plaque transfers of the virus, lead to fitness decrease (measured here as diminished capacity to produce infectious progeny). Here we report an analysis of fitness evolution of several low fitness foot-and-mouth disease virus clones subjected to 50 plaque-to-plaque transfers. Unexpectedly, fitness decrease, rather than being continuous and monotonic, displayed a fluctuating pattern, which was influenced by both the virus and the state of the host cell as shown by effects of recent cell passage history. The amplitude of the fluctuations increased as fitness decreased, resulting in a remarkable resistance of virus to extinction. Whereas the frequency distribution of fitness in control (independent) experiments follows a log-normal distribution, the probability of fitness values in the evolving bottlenecked populations fitted a Weibull distribution. We suggest that multiple functions of viral genomic RNA and its encoded proteins, subjected to high mutational pressure, interact with cellular components to produce this nontrivial, fluctuating pattern. PMID:12960384

  3. Simulations of beam-beam and beam-wire interactions in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung J.; Sen, Tanaji; /Fermilab; Abreu, Natalia P.; Fischer, Wolfram; /Brookhaven

    2009-02-01

    The beam-beam interaction is one of the dominant sources of emittance growth and luminosity lifetime deterioration. A current carrying wire has been proposed to compensate long-range beam-beam effects in the LHC and strong localized long-range beam-beam effects are experimentally investigated in the RHIC collider. Tune shift, beam transfer function, and beam loss rate are measured in dedicated experiments. In this paper, they report on simulations to study the effect of beam-wire interactions based on diffusive apertures, beam loss rates, and beam transfer function using a parallelized weak-strong beam simulation code (BBSIMC). The simulation results are compared with measurements performed in RHIC during 2007 and 2008.

  4. 预应力混凝土后张梁孔道摩阻损失试验分析%Research on the Experiment Test of Frictional Resistance Loss in Post-tensioning Pre-stressed Concrete Beam Pipe

    Institute of Scientific and Technical Information of China (English)

    叶恒梅

    2016-01-01

    The loss of frictional resistance in post -tesioning pre-stressed concrete beam pipe is a big problem during the construction of post-tesioning pre-stressed concrete bridge. The test of frictional resistance loss is important to the quality security and persistence of bridge construction. The formula of beam pipe frictional resistance loss co-effi-cient was calculated by least square method. This formula was applied on the xianhu bridge construction ,then the project of frictional resistance loss test of beam pipe was proposed to reduce the loss of pre-stress and analyze the practical data in the xianhu bridge construction.%在后张法预应力混凝土桥梁结构的建设中,预应力孔道摩阻损失问题十分突出。孔道摩阻测试对确保桥梁结构的施工质量、安全性和耐久性有着重要意义。以仙葫大桥为例,在公式分析的基础上结合最小二乘法原理,推导出孔道摩阻参数的计算公式,为减少预应力损失,提出了孔道摩阻试验检测的方案,同时对该桥现场测试数据进行了计算和分析。研究结果可为同类施工提供参考。

  5. A Study on SNR Loss of Beam Forming Resulted from Several Factors%影响波束合成信噪比若干因素的研究

    Institute of Scientific and Technical Information of China (English)

    朱新国; 张凯

    2012-01-01

    Considering the signal noise ration (SNR) loss of beam forming in practice, the SNR gain of digital beam forming is de-rivated under the ideal case in this paper. The factors of channel failure, amplitude weighting and amplitude-phase error, which can cause SNR performance deterioration of beam forming, are respectively studied, and the analytical expression of SNR loss is derivated. The simulation results indicate that it is approximately linear dependency between SNR loss and channel failure when the percent of disabled channel is below 30%; the SNR loss resulted from the simultaneous existence of channel failure, amplitude weighting and amplitude-phase error is approximately the sum of SNR loss resulted from them respetively.%针对实际工作中波束合成性能下降的问题,推导了理想情况下数字波束合成信噪比相对输入信噪比的增益,研究了通道失效、幅度加权和幅相误差分别对波束合成信噪比的影响,并推导了信噪比损失的解析式.理论分析和仿真结果表明:在失效通道比例小于30%的条件下,信噪比损失与失效通道比例近似成线性关系;在同时存在通道失效、幅度加权和幅相误差的条件下,信噪比损失近似等于通道失效、幅度加权和幅相误差各自引入的信噪比损失之和.

  6. Using cone beam computed tomography to detect the relationship between the periodontal bone loss and mucosal thickening of the maxillary sinus

    Directory of Open Access Journals (Sweden)

    Mahnaz Sheikhi

    2014-01-01

    Full Text Available Background: Maxillary sinuses are covered by a 1 mm thick mucous membrane that when this membrane becomes inflamed, the thickness may increase 10-15 times. The common causes of odontogenic sinusitis are dental abscesses and periodontal disease. Computed tomography (CT is considered the gold standard for sinus diagnosis. Recently, cone beam computed tomography (CBCT has been introduced for dental and maxillofacial imaging, which has several advantages over traditional CT, including lower radiation dose and chairside process. This study aims to find the association between mucosal thickening (MT of the sinus and periodontal bone loss (PBL and pulpoperiapical condition. Materials and Methods: A total of 180 CBCT images were reviewed. PBL was assessed in six points under each sinus at the mesial and distal sides of the upper second premolar and first and second molars by measuring the distance from the alveolar crest to the point 2 mm under the cemento-enamel junction (CEJ. The MT was assessed at six points in the floor of the sinus precisely over the mentioned points. To assess the possible role of pulpoperiapical condition on the sinus MT, the existing teeth were classified into five groups due to the probable effect of each condition on the pulp and peri-apex. The statistical association between MT of sinus and PBL and pulpoperiapical condition was assessed using SPSS software (SPSS Inc., version 16.0, Chicago, IL, USA and bivariate correlation and binary linear regression statistical tests (P < 0.05. Results: MT was observed in 39.4% of patients (mean = 4.68 ± 5.25 mm. PBL was seen in 33% of the patients (mean = 1.87 ± 1.63 mm. Linear regression test showed that there is an association between both PBL and pulpoperiapical condition and MT, but the effect of PBL was about 4 times stronger. Conclusion: This study showed that MT of the maxillary sinus was common among patients with PBL and MT of the maxillary sinus was significantly associated

  7. Junction size dependence of ferroelectric properties in e-beam patterned BaTiO{sub 3} ferroelectric tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Singh, A. V.; Gupta, A. [Center for Materials for Information Technology, The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Althammer, M. [Center for Materials for Information Technology, The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Walther-Meissner-Institut, Bayerische Akdademie der Wissenschaften, Garching 85748 (Germany); Rott, K.; Reiss, G. [Thin Films and Physics of Nanostructures, Department of Physics and Center for Spinelectronic Materials and Devices, Bielefeld University, Bielefeld 33615 (Germany)

    2015-09-21

    We investigate the switching characteristics in BaTiO{sub 3}-based ferroelectric tunnel junctions patterned in a capacitive geometry with circular Ru top electrode with diameters ranging from ∼430 to 2300 nm. Two different patterning schemes, viz., lift-off and ion-milling, have been employed to examine the variations in the ferroelectric polarization, switching, and tunnel electro-resistance resulting from differences in the pattering processes. The values of polarization switching field are measured and compared for junctions of different diameter in the samples fabricated using both patterning schemes. We do not find any specific dependence of polarization switching bias on the size of junctions in both sample stacks. The junctions in the ion-milled sample show up to three orders of resistance change by polarization switching and the polarization retention is found to improve with increasing junction diameter. However, similar switching is absent in the lift-off sample, highlighting the effect of patterning scheme on the polarization retention.

  8. Reliability of the beam loss monitors system for the large hadron collider at CERN; Fiabilite du systeme des moniteurs de pertes du faisceau pour le Large Hadron Collider au CERN

    Energy Technology Data Exchange (ETDEWEB)

    Guaglio, G

    2005-12-15

    The energy stored in the Large Hadron Collider is unprecedented. The impact of the beam particles can cause severe damage on the superconductive magnets, resulting in significant downtime for repairing. The Beam Loss Monitors System (BLMS) detects the secondary particles shower of the lost beam particles and initiates the extraction of the beam before any serious damage to the equipment can occur. This thesis defines the BLMS specifications in term of reliability. The main goal is the design of a system minimizing both the probability to not detect a dangerous loss and the number of false alarms generated. The reliability theory and techniques utilized are described. The prediction of the hazard rates, the testing procedures, the Failure Modes Effects and Criticalities Analysis and the Fault Tree Analysis have been used to provide an estimation of the probability to damage a magnet, of the number of false alarms and of the number of generated warnings. The weakest components in the BLMS have been pointed out. The reliability figures of the BLMS have been calculated using a commercial software package (Isograph.). The effect of the variation of the parameters on the obtained results has been evaluated with a sensitivity analysis. The reliability model has been extended by the results of radiation tests. Design improvements, like redundant optical transmission, have been implemented in an iterative process. The proposed system is compliant with the reliability requirements. The model uncertainties are given by the limited knowledge of the thresholds levels of the superconductive magnets and of the locations of the losses along the ring. The implemented model allows modifications of the system, following the measuring of the hazard rates during the LHC life. It can also provide reference numbers to other accelerators which will implement similar technologies. (author)

  9. Objectives and design of the Echo 6 electron beam experiment - Large ionospheric perturbations and energetic particle patterns

    Science.gov (United States)

    Winckler, J. R.; Steffen, J. E.; Malcolm, P. R.; Erickson, K. N.; Abe, Y.

    1985-01-01

    The data from the March 30, 1983 launching of Echo 6 are presented. Echo 6 contained duplex accelerators and a system of four throw away detectors to detect and analyze conjugate electron echoes. The model used to calculate the proper trajectory of the rocket and the reason for not detecting echoes are discussed. The components of the plasma diagnostic package which was used to study the electron beam interactions with the ionospheric plasma, and the functions of the two controllable electron guns and the two sets of orthogonal electric probes are described. The signal-mode potentials between each probe and the plasma diagnostic payload are investigated. The signals produced by the gun pulses are analyzed and the interpretation of the electric field probe response is examined.

  10. Beam patterns in an optical parametric oscillator set-up employing walk-off compensating beta barium borate crystals

    Science.gov (United States)

    Kaucikas, M.; Warren, M.; Michailovas, A.; Antanavicius, R.; van Thor, J. J.

    2013-02-01

    This paper describes the investigation of an optical parametric oscillator (OPO) set-up based on two beta barium borate (BBO) crystals, where the interplay between the crystal orientations, cut angles and air dispersion substantially influenced the OPO performance, and especially the angular spectrum of the output beam. Theory suggests that if two BBO crystals are used in this type of design, they should be of different cuts. This paper aims to provide an experimental manifestation of this fact. Furthermore, it has been shown that air dispersion produces similar effects and should be taken into account. An x-ray crystallographic indexing of the crystals was performed as an independent test of the above conclusions.

  11. A new method for cone beam CT measurements of cyst of jaw bone loss%锥体束CT测量颌骨囊肿骨量缺失的新方法

    Institute of Scientific and Technical Information of China (English)

    张冬梅; 李锐; 李晓燕; 常平

    2015-01-01

    目的:探讨利用锥体束CT预测颌骨囊肿骨量缺失的新方法。方法:随机选取我院接诊的颌骨囊肿患者作为研究对象,拍摄锥体束CT,利用eXamVision软件进行测量,采用公式V=X*Y*Z对颌骨骨量缺失进行预测。结果:该方法所得数据能近似得出颌骨囊肿骨量缺失体积。结论:对颌骨囊肿缺失骨量的术前预测有助于术中植骨及手术方案的选择,锥体束CT能较准确的预测骨量的缺失体积,具有较好的临床指导意义。%Objective To study a new method for prediction of cyst of jaw bone loss by cone beam CT. Methods Random selection of jaw cyst patients as the research object, shooting cone beam CT,were measured using the eXamVision software, using the formula V=X*Y*Z to predict bone loss. Results The data from this method can approximate the missing volume of jaw cyst. Conclusion Contribute to bone grafting and operation scheme for the prediction of cyst of jaw bone loss of the preoperative selection. Cone beam CT can predict accurately the loss of bone volume, has better clinical directive significance.

  12. Pattern of hair cell loss and delayed peripheral neuron degeneration in inner ear by a high-dose intratympanic gentamicin

    Institute of Scientific and Technical Information of China (English)

    Jintao Yu; Dalian Ding; Fengjun Wang; Haiyan Jiang; Hong Sun; Richard Salvi

    2014-01-01

    To gain insights into the ototoxic effects of aminoglycoside antibiotics (AmAn) and delayed peripheral ganglion neuron death in the inner ear, experimental animal models were widely used with several different approaches including AmAn systemic injections, combination treat-ment of AmAn and diuretics, or local application of AmAn. In these approaches, systemic AmAn treatment alone usually causes incomplete damage to hair cells in the inner ear. Co-administration of diuretic and AmAn can completely destroy the cochlear hair cells, but it is impossible to damage the vestibular system. Only the approach of AmAn local application can selectively eliminate most sensory hair cells in the inner ear. Therefore, AmAn local application is more suitable for studies for complete hair cell destructions in cochlear and vestibular system and the following delayed peripheral ganglion neuron death. In current studies, guinea pigs were unilaterally treated with a high concentration of gentamicin (GM, 40 mg/ml) through the tympanic membrane into the middle ear cavity. Auditory functions and vestibular functions were measured before and after GM treatment. The loss of hair cells and delayed degeneration of ganglion neurons in both cochlear and vestibular system were quantified 30 days or 60 days after treatment. The results showed that both auditory and vestibular functions were completely abolished after GM treatment. The sensory hair cells were totally missing in the cochlea, and severely destroyed in vestibular end-organs. The delayed spiral ganglion neuron death 60 days after the deafening procedure was over 50%. However, no obvious pathological changes were observed in vestibular ganglion neurons 60 days post-treatment. These results indicated that a high concentration of gentamycin delivered to the middle ear cavity can destroy most sensory hair cells in the inner ear that subsequently causes the delayed spiral ganglion neuron degeneration. This model might be useful for studies

  13. Direct fabrication of nanoscale bio-adhesive patterns by electron beam surface modification of plasma polymerized poly ethylene oxide-like coatings.

    Science.gov (United States)

    Brétagnol, Frédéric; Sirghi, Lucel; Mornet, Stéphane; Sasaki, Takao; Gilliland, Douglas; Colpo, Pascal; Rossi, Francois

    2008-03-26

    In this study we present a method to produce nanostructured surfaces containing bio-adhesive features inside a non bio-adhesive matrix. The strategy is based on the combination of low pressure plasma polymerization and electron beam lithography processes and allows the fabrication of the structured materials in just two steps without using any solvents. In a first step, a thin protein-and-cell-repelling coating (∼10 nm) is obtained by plasma polymerization of Di-glyme. Then, in a second step, the bio-adhesive properties of the layer are tuned by monitoring the concentration of ether bonds of the film by irradiating it locally by different irradiation doses with an electron beam. Time-of-flight secondary ion mass spectroscopy and atomic force microscopy analysis have been used to characterize the produced surfaces. Experiments with a model protein (bovine serum albumin) on the patterned surfaces show preferential adhesion to the irradiated regions, indicating the potential of this simple technique for the development of highly compacted sensitive bio-sensing devices.

  14. Studies of the beam extraction system of the GTS-LHC electron cyclotron resonance ion source at CERN.

    Science.gov (United States)

    Toivanen, V; Küchler, D

    2016-02-01

    The 14.5 GHz GTS-LHC Electron Cyclotron Resonance Ion Source (ECRIS) provides multiply charged heavy ion beams for the CERN experimental program. The GTS-LHC beam formation has been studied extensively with lead, argon, and xenon beams with varied beam extraction conditions using the ion optical code IBSimu. The simulation model predicts self-consistently the formation of triangular and hollow beam structures which are often associated with ECRIS ion beams, as well as beam loss patterns which match the observed beam induced markings in the extraction region. These studies provide a better understanding of the properties of the extracted beams and a way to diagnose the extraction system performance and limitations, which is otherwise challenging due to the lack of direct diagnostics in this region and the limited availability of the ion source for development work.

  15. Study of growth properties of InAs islands on patterned InP substrates defined by focused ion beam

    Science.gov (United States)

    Ribeiro-Andrade, R.; Malachias, A.; Miquita, D. R.; Vasconcelos, T. L.; Kawabata, R.; Pires, M. P.; Souza, P. L.; Rodrigues, W. N.

    2017-03-01

    This work describes morphological and crystalline properties of the InAs islands grown on templates created by focused ion beam (FIB) on indium phosphide (InP) substrates. Regular arrangements of shallow holes are created on the InP (001) surfaces, acting as preferential nucleation sites for InAs islands grown by Metal-Organic Vapor Phase Epitaxy. Ion doses ranging from 1015 to 1016 Ga+/cm2 were used and islands were grown for two sub-monolayer coverages. We observe the formation of clusters in the inner surfaces of the FIB produced cavities and show that for low doses templates the nanostructures are mainly coherent while templates created with large ion doses lead to the growth of incoherent islands with larger island density. The modified island growth is described by a simple model based on the surface potential and the net adatom flow to the cavities. We observe that obtained morphologies result from a competition between coarsening and coalescence mechanisms.

  16. Patterning of rutile TiO{sub 2} surface by ion beam lithography through full-solid masks

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, R; Jaafar, M; Asenjo, A; Vazquez, M [Instituto de Ciencia de Materiales de Madrid (CSIC), 28049, Madrid (Spain); Hernandez-Velez, M [Departamento de Fisica Aplicada, GMNF, Unidad Asociada al ICMM-CSIC, Universidad Autonoma de Madrid, Cantoblanco, 28049, Madrid (Spain); Jensen, J, E-mail: rsanz@nanoate.com [Thin Film Physics, Department of Physics, Chemistry and Biology, Linkoeping University, SE-581 83 Linkoeping (Sweden)

    2010-06-11

    In this work we present and discuss the nanopatterning of rutile TiO{sub 2} single crystal surfaces following their irradiation with energetic heavy ions through a stencil mask of Ni filled self-ordered porous anodic alumina. After etching in HF a corrugated surface morphology is obtained composed of parallel alternate furrows and ridges (or nanobars) 50 nm in diameter and with 100 nm pitch. In addition, isolated, but collapsed, TiO{sub 2} nanorods are seen lying on the patterned surface. The stability of the nanopatterned surface under high temperatures treatments and crystalline properties are analyzed.

  17. Successful long-term weight loss among participants with diabetes receiving an intervention promoting an adapted Mediterranean-style dietary pattern: the Heart Healthy Lenoir Project

    Science.gov (United States)

    Embree, Genevieve G R; Samuel-Hodge, Carmen D; Johnston, Larry F; Garcia, Beverly A; Gizlice, Ziya; Evenson, Kelly R; DeWalt, Darren A; Ammerman, Alice S; Keyserling, Thomas C

    2017-01-01

    Objective To examine weight change by diabetes status among participants receiving a Mediterranean-style diet, physical activity, and weight loss intervention adapted for delivery in the southeastern USA, where rates of cardiovascular disease (CVD) are disproportionately high. Research design and methods The intervention included: Phase I (months 1–6), an individually tailored intervention promoting a Mediterranean-style dietary pattern and increased walking; Phase II (months 7–12), option of a 16-week weight loss intervention for those with BMI≥25 kg/m2 offered as 16 weekly group sessions or 5 group sessions and 10 phone calls, or a lifestyle maintenance intervention; and Phase III (months 13–24), weight loss maintenance intervention for those losing ≥8 pounds with all others receiving a lifestyle maintenance intervention. Weight change was assessed at 6, 12, and 24-month follow-up. Results Baseline characteristics (n=339): mean age 56, 77% female, 65% African-American, 124 (37%) with diabetes; mean weight 103 kg for those with diabetes and 95 kg for those without. Among participants with diabetes, average weight change was −1.2 kg (95% CI −2.1 to −0.4) at 6 months (n=92), −1.5 kg (95% CI −2.9 to −0.2) at 12 months (n=96), and −3.7 kg (95% CI −5.2 to −2.1) at 24 months (n=93). Among those without diabetes, weight change was −0.4 kg (95% CI −1.4 to 0.6) at 24 months (n=154). Conclusions Participants with diabetes experienced sustained weight loss at 24-month follow-up. High-risk US populations with diabetes may experience clinically important weight loss from this type of lifestyle intervention. Trial registration number NCT01433484.

  18. 基于改进粒子群算法的共形阵列天线综合%Conformal Antenna Array Beam Pattern Synthesis Based on Improved Particle Swarm Optimization

    Institute of Scientific and Technical Information of China (English)

    杨永建; 王晟达; 马健; 甘轶; 邓有为

    2012-01-01

    共形阵列天线的赋形方向图综合涉及大量的运算,成为现在研究的一大难点,目前对共形阵方向图综合的研究比较少,且所用算法存在理论复杂、耗时长的缺点.文中运用改进粒子群算法对圆环阵、圆柱阵方向图的综合进行了研究,仿真结果表明,改进粒子群算法能够较快地形成期望方向图,证明了该方法的有效性和实用性.%The shaped of conformal antenna array beam pattern synthesis is one of difficulties in array antennas beam pattern, because larger numbers of operation is needed. Presently, the research for conformal array antennabeam pattern synthesis is less, and the used arithmetic is complex in theoretics and need more times. Improved particle swarm optimization (PSO) to synthetize circu-larand columniform array beam pattern is used, the result of simulation shows the improved optimization can form desired beam pattern quickly, and proves the method is effective and practicability.

  19. Hierarchical multiple bit clusters and patterned media enabled by novel nanofabrication techniques -- High resolution electron beam lithography and block polymer self assembly

    Science.gov (United States)

    Xiao, Qijun

    This thesis discusses the full scope of a project exploring the physics of hierarchical clusters of interacting nanomagnets. These clusters may be relevant for novel applications such as multilevel data storage devices. The work can be grouped into three main activities: micromagnetic simulation, fabrication and characterization of proof-of-concept prototype devices, and efforts to scale down the structures by creating the hierarchical structures with the aid of diblock copolymer self assembly. Theoretical micromagnetic studies and simulations based on Landau-Lifshitz-Gilbert (LLG) equation were conducted on nanoscale single domain magnetic entities. For the simulated nanomagnet clusters with perpendicular uniaxial anisotropy, the simulation showed the switching field distributions, the stability of the magnetostatic states with distinctive total cluster perpendicular moments, and the stepwise magnetic switching curves. For simulated nanomagnet clusters with in-plane shape anisotropy, the simulation showed the stepwise switching behaviors governed by thermal agitation and cluster configurations. Proof-of-concept cluster devices with three interacting Co nanomagnets were fabricated by e-beam lithography (EBL) and pulse-reverse electrochemical deposition (PRECD). EBL patterning on a suspended 100 nm SiN membrane showed improved lateral lithography resolution to 30 nm. The Co nanomagnets deposited using the PRECD method showed perpendicular anisotropy. The switching experiments with external applied fields were able to switch the Co nanomagnets through the four magnetostatic states with distinctive total perpendicular cluster magnetization, and proved the feasibility of multilevel data storage devices based on the cluster concept. Shrinking the structures size was experimented by the aid of diblock copolymer. Thick poly(styrene)-b-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer templates aligned with external electrical field were used to fabricate long Ni

  20. Temporal pattern of loss/persistence of duplicate genes involved in signal transduction and metabolic pathways after teleost-specific genome duplication

    Directory of Open Access Journals (Sweden)

    Sato Yukuto

    2009-06-01

    Full Text Available Abstract Background Recent genomic studies have revealed a teleost-specific third-round whole genome duplication (3R-WGD event occurred in a common ancestor of teleost fishes. However, it is unclear how the genes duplicated in this event were lost or persisted during the diversification of teleosts, and therefore, how many of the duplicated genes contribute to the genetic differences among teleosts. This subject is also important for understanding the process of vertebrate evolution through WGD events. We applied a comparative evolutionary approach to this question by focusing on the genes involved in long-term potentiation, taste and olfactory transduction, and the tricarboxylic acid cycle, based on the whole genome sequences of four teleosts; zebrafish, medaka, stickleback, and green spotted puffer fish. Results We applied a state-of-the-art method of maximum-likelihood phylogenetic inference and conserved synteny analyses to each of 130 genes involved in the above biological systems of human. These analyses identified 116 orthologous gene groups between teleosts and tetrapods, and 45 pairs of 3R-WGD-derived duplicate genes among them. This suggests that more than half [(45×2/(116+45] = 56.5% of the loci, probably more than ten thousand genes, present in a common ancestor of the four teleosts were still duplicated after the 3R-WGD. The estimated temporal pattern of gene loss suggested that, after the 3R-WGD, many (71/116 of the duplicated genes were rapidly lost during the initial 75 million years (MY, whereas on average more than half (27.3/45 of the duplicated genes remaining in the ancestor of the four teleosts (45/116 have persisted for about 275 MY. The 3R-WGD-derived duplicates that have persisted for a long evolutionary periods of time had significantly larger number of interacting partners and longer length of protein coding sequence, implying that they tend to be more multifunctional than the singletons after the 3R-WGD. Conclusion

  1. Spatial and temporal patterns of spontaneous grass cover as a control measure of soil loss: a study case in an olive orchard microcatchment

    Science.gov (United States)

    Taguas, Encarnación; Vanderlinden, Karl; Pedrera-Parrilla, Aura; Giráldez, Juan V.; Gómez, Jose A.

    2016-04-01

    Spatial and temporal patterns of vegetal communities control local biogeophysical processes.. The use of cover crops and spontaneous grass cover as a soil erosion control measure is quite common, particularly in hilly agricultural areas. Spontaneous covers show usually irregular spatial and temporal patterns, resulting in a questionable efficiency and and unresolved management requirements. However, due to its zero cost, it is a helpful alternative for soil erosion control in marginal farms (Taguas et al., 2015). The main aim of this work was to characterize the spatial and temporal patterns of spontaneous grass cover in an olive orchard microcatchment to interpret its dependences on other physical features as well as its influence on soil loss control. The specific objectives were: i) to evaluate the relationships between the mean cover and the variables: accumulated precipitation, accumulated evapotranspiration and average minimum temperature for the preceding 5, 15, 30 and 60 days to the sampling date; ii) study the spatial aggregation degree of the cover, its temporal stability and its correlation with different topographical properties, the richness of species and the apparent electrical conductivity as a measure of soil variability; and iii) describe the influence of the cover on runoff and soil loss in the catchments. Cover percentage corresponding to spontaneous grass was evaluated on a seaonsal basis during 3 years (2011-2013), resulting in 12 surveys. A permanent and regular grid of 36 points covering the entire catchment (5-6 samples/ha) was used in each survey. At each location cover percentage was determined through image analyses. In order to explore the relations between cover percentage and meteorological variables, multiple linear regression was applied whereas the SADIE approach (Spatial analysis by distance indices; Perry, 1998) was used to describe possible spatial aggregation patterns and the correlation with features such as aspect, slope

  2. Combined crossed molecular beam and ab initio investigation of the multichannel reaction of boron monoxide (BO; X2Σ+) with Propylene (CH3CHCH2; X1A'): competing atomic hydrogen and methyl loss pathways.

    Science.gov (United States)

    Maity, Surajit; Dangi, Beni B; Parker, Dorian S N; Kaiser, Ralf I; An, Yi; Sun, Bing-Jian; Chang, A H H

    2014-10-16

    The reaction dynamics of boron monoxide ((11)BO; X(2)Σ(+)) with propylene (CH(3)CHCH(2); X(1)A') were investigated under single collision conditions at a collision energy of 22.5 ± 1.3 kJ mol(-1). The crossed molecular beam investigation combined with ab initio electronic structure and statistical (RRKM) calculations reveals that the reaction follows indirect scattering dynamics and proceeds via the barrierless addition of boron monoxide radical with its radical center located at the boron atom. This addition takes place to either the terminal carbon atom (C1) and/or the central carbon atom (C2) of propylene reactant forming (11)BOC(3)H(6) intermediate(s). The long-lived (11)BOC(3)H(6) doublet intermediate(s) underwent unimolecular decomposition involving at least three competing reaction mechanisms via an atomic hydrogen loss from the vinyl group, an atomic hydrogen loss from the methyl group, and a methyl group elimination to form cis-/trans-1-propenyl-oxo-borane (CH(3)CHCH(11)BO), 3-propenyl-oxo-borane (CH(2)CHCH(2)(11)BO), and ethenyl-oxo-borane (CH(2)CH(11)BO), respectively. Utilizing partially deuterated propylene (CD(3)CHCH(2) and CH(3)CDCD(2)), we reveal that the loss of a vinyl hydrogen atom is the dominant hydrogen elimination pathway (85 ± 10%) forming cis-/trans-1-propenyl-oxo-borane, compared to the loss of a methyl hydrogen atom (15 ± 10%) leading to 3-propenyl-oxo-borane. The branching ratios for an atomic hydrogen loss from the vinyl group, an atomic hydrogen loss from the methyl group, and a methyl group loss are experimentally derived to be 26 ± 8%:5 ± 3%:69 ± 15%, respectively; these data correlate nicely with the branching ratios calculated via RRKM theory of 19%:5%:75%, respectively.

  3. 基于DPSO算法的半球共形阵方向图综合%Hemispherical conformal antenna array beam pattern synthesis based on Dichotomy Particle Swarm Optimization

    Institute of Scientific and Technical Information of China (English)

    马颖; 田维坚; 樊养余

    2013-01-01

    针对共形阵列天线方向图综合所需迭代次数大,且算法的收敛对初始值敏感问题,本文采用DPSO算法对半球共形阵赋形方向图综合进行了研究,通过对半球共球阵模型的建立,推导了所建模型的方向图函数.仿真结果表明,DPSO算法能够较快地综合半球共形阵的赋形方向图,是一种高效且实用的综合算法.%DPSO (Dichotomy Particle Swarm Optimization) algorithm was used to synthesize hemispherical conformal antenna array beam pattern,aimed at the accustomed algorithms of conformal array antenna beam pattern synthesis have a great iterative time and the constringency depending on the value of initialization.Based on the model of hemispherical conformal array,the beam pattern mathematic function of the array is put up.The result of simulation shows DPSO algorithm can form desired beam pattern quickly,and proves the method is effective and practicability.

  4. 洛阳博物馆新馆大跨度框架梁预应力损失测试研究%Prestressing Loss Test of the Large Span Frame Beam of Luoyang New Museum

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    In Luoyang New Museum, the prestressing loss monitoring and testing play very important role in the process of tensioning, especially for the prestressed control of the construction sequence of a large span prestressed frame beam adopting the post⁃tensioned prestressed technology. The measured values of stress and strain of the beam characteristic cross section are compared with the theoretical design calculation ones, based on the coefficient of friction loss accurately obtained in this paper. Finally, it can achieve the purpose of precise control of the prestressing construction quality.%洛阳博物馆新馆工程大跨度预应力框架梁采用后张有黏结预应力施工工艺,施工过程中应加强其预应力施工控制,特别是张拉过程中的预应力损失监控及测试十分重要。通过精确计算出摩阻损失系数,测定出特征截面的应力和应变值,并与理论设计验算值进行对比分析,可达到精确控制预应力施工质量的目的。

  5. Study of Intensity Proton Accelerator Beam Loss Readout System%强流质子加速器的束流损失读出系统的研究

    Institute of Scientific and Technical Information of China (English)

    马晓媛; 雷革; 徐韬光

    2012-01-01

    It introduces the research on the Beam - Loss - Readout system, which is part of the Beam - Loss -Monitoring system of the intensity proton accelerator. The hardware scheme of BLR system use ADC sampling e-quipment based on VME bus protocol. The software design is built on the Linux platform using EPICS control system. With the device driver, device support and record support program, the system gets control of the device and reads out the data. It turns out to meet the requirements of the project target.%介绍了强流质子加速器束流损失监测系统中束流损失读出系统的研究.束损读出系统硬件使用基于VME总线协议的ADC设备,软件设计采用EPICS控制软件框架.作者编写设备驱动、设备支持、记录支持程序,实现了对硬件的控制和数据的读取,并满足工程要求的性能指标.

  6. Bunch-by-bunch beam loss monitor system in BEPCⅡ storage ring%BEPCⅡ储存环逐束团丢束监测系统及应用

    Institute of Scientific and Technical Information of China (English)

    邓庆勇; 曹建社; 岳军会; 魏源源; 麻惠洲; 杜垚垚

    2014-01-01

    A new prototype system for bunch-by-bunch beam position measurement has been designed and built to monitor and analyse the beam loss in the Beijing Electron-Positron ColliderⅡ(BEPCⅡ)storage ring.The fast ADC is used to sample the analog signals from the beam position monitor,then the digital signal is processed further using programmable gate array (FP-GA).The beam information can be obtained by means of bunch-by-bunch,such as bunch position,bunch current and bunch tune.Based on system monitoring and data analysis for long terms,as well as the dedicated machine experiments,it’s relatively clear for operators to understand some trip events,especially the beam loss caused by the high-frequency cavity trip,tune drift and multiple bunch instability.The study proves that the system is very useful for the operation of accelerator.%针对北京正负电子对撞机二期工程(BEPCⅡ)在高流强下运行经常出现的突然丢束问题,研制了基于逐束团测量的丢束监测系统。束流位置探头(BPM)的四路电极信号作为监测系统的信号源,四路高速模数转换器(ADC)和现场可编程门阵列(FPGA)进行模拟信号的数字化和数字信号的处理。通过获取丢束前每个束团的位置和流强等信息来分析引起丢束的原因。结合加速器硬件情况,长时间对丢束监测系统数据的分析,以及设计的对比实验,深入研究丢束问题。系统对高频系统故障、束流不稳定性和磁铁电源系统不稳定等原因引起的丢束现象可以做出准确的判断,进而为加速器稳定运行提供优化方向。

  7. Investigation of Moiré pattern-based phase retrieval approach for differential phase-contrast cone beam CT imaging using a hospital-grade tube

    Science.gov (United States)

    Cai, Weixing; Ning, Ruola; Yu, Yang; Liu, Jiangkun; Conover, David

    2012-03-01

    The phase stepping algorithm is commonly used for phase retrieval in grating-based differential phase-contrast (DPC) imaging, which requires multiple intensity images to compute one DPC image. It is not efficient for data acquisition, especially in the case of dynamic imaging using either DPC imaging or DPC-based come beam CT (DPC-CBCT) imaging. A Fourier transform-based approach has been developed for fringe pattern analysis in optics, and it was recently implemented into a synchrotron-based DPC tomography system. In this research, this approach is further developed for a bench-top DPC-CBCT imaging system with a hospital-grade x-ray tube. The key idea is to separate carrier fringes and object information in Fourier domain of the interferogram and to reconstruct the differentiated phase information using the object information. Only one interferogram is required for phase retrieval at a cost of spatial resolution. The fringes of moiré patterns are used as the carrier fringes, and a phantom is scanned to evaluate the approach. Various interferograms with different carrier fringe frequencies are investigated and the reconstruction image quality is evaluated in terms of contrast, noise and sharpness. The results indicated that the DPC images can be effectively retrieved using the Fourier transform-based approach and the reconstructed phase coefficient showed better contrast compared to that of attenuation-based contrast. The spatial resolution is acceptable in the phantom studies although it is not as good as the results of phase-stepping approach. The Fourier transform-based phase retrieval approach is able to greatly simplify data acquisition, to improve the temporal resolution and to make it possible for dynamic DPC-CBCT imaging. It is promising for perfusion imaging where spatial resolution is not a concern.

  8. Evaluation of upper airways after bimaxillary orthognathic surgery in patients with skeletal Class III pattern using cone-beam computed tomography

    Directory of Open Access Journals (Sweden)

    Marília Spínola Azevêdo

    2016-02-01

    Full Text Available Introduction: It has been suggested that mandibular setback surgery, combined or not with maxillary advancement as a treatment alternative for patients with mandibular prognathism, can induce changes in upper airway space (UAS. Therefore, this study aimed to assess the response of the upper airway in the oropharynx region of patients with Class III skeletal pattern that underwent bimaxillary orthognathic surgery (maxillary advancement and mandibular setback combined with mentoplasty. Material and Methods: The sample comprised 26 cone-beam computed tomography (CBCT scans of 13 patients. The examination was taken before and after surgery. UAS volume, sagittal area, length and minimal axial area with its width, depth and location, were measured with the aid of Dolphin ImagingTMsoftware version 11.5 Premium. Data were statistically treated by applying Shapiro-Wilk test and Student's paired t-test, considering as statistically significant the results of which p-value was lower than 0.05. Results: No statistically significant differences were found in any measurements evaluated. Conclusions: No significant changes were observed in the oropharynx after bimaxillary orthognathic surgery and mentoplasty.

  9. Site-specific forest-assembly of single-wall carbon nanotubes on electron-beam patterned SiO{sub x}/Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Wei Haoyan [Materials Science and Engineering Program, Department of Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States); Kim, Sang Nyon; Kim, Sejong [Nanomaterials Optoelectronics Laboratory, Polymer Program, Institute of Materials Science, Department of Chemistry, University of Connecticut, Storrs, CT 06269 (United States); Huey, Bryan D. [Materials Science and Engineering Program, Department of Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States); Papadimitrakopoulos, Fotios [Nanomaterials Optoelectronics Laboratory, Polymer Program, Institute of Materials Science, Department of Chemistry, University of Connecticut, Storrs, CT 06269 (United States); Marcus, Harris L. [Materials Science and Engineering Program, Department of Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States)], E-mail: hmarcus@ims.uconn.edu

    2008-12-01

    Based on electron-beam direct writing on the SiO{sub x}/Si substrates, favorable absorption sites for ferric cations (Fe{sup 3+} ions) were created on the surface oxide layer. This allowed Fe{sup 3+}-assisted self-assembled arrays of single-wall carbon nanotube (SWNT) probes to be produced. Auger investigation indicated that the incident energetic electrons depleted oxygen, creating more dangling bonds around Si atoms at the surface of the SiO{sub x} layer. This resulted in a distinct difference in the friction forces from unexposed regions as measured by lateral force microscopy (LFM). Atomic force microscopy (AFM) affirmed that the irradiated domains absorbed considerably more Fe{sup 3+} ions upon immersion into pH 2.2 aqueous FeCl{sub 3} solution. This rendered a greater yield of FeO(OH)/FeOCl precipitates, primarily FeO(OH), upon subsequent washing with lightly basic dimethylformamide (DMF) solution. Such selective metal-functionalization established the basis for the subsequent patterned forest-assembly of SWNTs as demonstrated by resonance Raman spectroscopy.

  10. Thermal evaluation of different DC multi-conductor cable cross-sections and installation patterns for the CLIC drive-beam quadrupoles

    CERN Document Server

    Maglio, D

    2007-01-01

    The main goal of this study is to determine the thermal behaviour of different dc multi-conductor cable cross-sections and installations patterns for the CLIC drive beam quadrupoles loaded with increasing values of current intensity. A simplified two dimensional model of the heat transfer problem was prepared with a commercial CFD software, STAR-CD 4.2. The heat flux generated by Joule effect in conductors was estimated taking into account the current value per conductor and the temperature dependence of the copper electrical resistance. In parallel, a geometrical simplification of the problem has been done in order to be able to apply theoretical formulas which have been implemented by Microsoft Excel. Obtained results have been compared with those got by the dedicated software, showing between them a good correspondence for two-conductor cables and confirming, for this case, the rules given in the in the French norm NF C15-100. In case of multiconductor cables, attention is to be paid to the temperature lev...

  11. Citation patterns of a controversial and high-impact paper: Worm et al. (2006 "Impacts of biodiversity loss on ocean ecosystem services".

    Directory of Open Access Journals (Sweden)

    Trevor A Branch

    Full Text Available Citation patterns were examined for Worm et al. 2006 (Science 314:787-790, a high-impact paper that focused on relationships between marine biodiversity and ecosystem services. This paper sparked much controversy through its projection, highlighted in the press release, that all marine fisheries would be collapsed by 2048. Analysis of 664 citing papers revealed that only a small percentage (11% referred to the 2048 projection, while 39% referred to fisheries collapse in general, and 40% to biodiversity and ecosystem services. The 2048 projection was mentioned more often in papers published soon after the original paper, in low-impact journals, and in journals outside of fields that would be expected to focus on biodiversity. Citing papers also mentioned the 2048 projection more often if they had few authors (28% of single-author papers vs. 2% of papers with 10 or more authors. These factors suggest that the more knowledgeable the authors of citing papers were about the controversy over the 2048 projection, the less likely they were to refer to it. A noteworthy finding was that if the original authors were also involved in the citing papers, they rarely (1 of 55 papers, 2% mentioned the 2048 projection. Thus the original authors have emphasized the broader concerns about biodiversity loss, rather than the 2048 projection, as the key result of their study.

  12. Citation patterns of a controversial and high-impact paper: Worm et al. (2006) "Impacts of biodiversity loss on ocean ecosystem services".

    Science.gov (United States)

    Branch, Trevor A

    2013-01-01

    Citation patterns were examined for Worm et al. 2006 (Science 314:787-790), a high-impact paper that focused on relationships between marine biodiversity and ecosystem services. This paper sparked much controversy through its projection, highlighted in the press release, that all marine fisheries would be collapsed by 2048. Analysis of 664 citing papers revealed that only a small percentage (11%) referred to the 2048 projection, while 39% referred to fisheries collapse in general, and 40% to biodiversity and ecosystem services. The 2048 projection was mentioned more often in papers published soon after the original paper, in low-impact journals, and in journals outside of fields that would be expected to focus on biodiversity. Citing papers also mentioned the 2048 projection more often if they had few authors (28% of single-author papers vs. 2% of papers with 10 or more authors). These factors suggest that the more knowledgeable the authors of citing papers were about the controversy over the 2048 projection, the less likely they were to refer to it. A noteworthy finding was that if the original authors were also involved in the citing papers, they rarely (1 of 55 papers, 2%) mentioned the 2048 projection. Thus the original authors have emphasized the broader concerns about biodiversity loss, rather than the 2048 projection, as the key result of their study.

  13. Efficacy of Cistanche Tubulosa and Laminaria Japonica Extracts (MK-R7) Supplement in Preventing Patterned Hair Loss and Promoting Scalp Health.

    Science.gov (United States)

    Seok, Joon; Kim, Tae Su; Kwon, Hyun Jung; Lee, Sung Pyo; Kang, Myung Hwa; Kim, Beom Joon; Kim, Myeung Nam

    2015-04-01

    Cistanche tubulosa and Laminaria japonica have been reported to have anti-oxidative, anticoagulant, anti-cancer and anti-inflammatory properties. They are expected to be a promising candidates for promoting hair growth and treating dandruff and scalp inflammation as a consequence. In this double-blinded, placebo-controlled clinical trial, we investigated the efficacy of Cistanche tubulosa extract and Laminaria japonica extract complex (MK-R7) in promoting hair health in patients with mild to moderate patterned hair loss. Using phototrichogram (Folliscope 4.0, LeadM, Seoul, Korea), we compared the density and diameter of hairs in patients receiving a placebo or Cistanche tubulosa extract and Laminaria japonica extract complex (MK-R7) at baseline, 8 and 16 weeks of the study. In order to determine the efficacy of treatment on dandruff and scalp inflammation, investigator's assessment score and patient's subjective score were also performed. We found a statistically significant increase in the hair density of the test group (n = 45, MK-R7 400 mg) after 16 weeks of consuming the MK-R7 (test group: 23.29 n/cm(2) ± 24.26, control: 10.35 n/cm(2) ± 20.08, p hair diameter in the test group compared to control group at week 16 (test group: 0.018 mm ± 0.015, control: 0.003 mm ± 0.013, p hair.

  14. Brief Discussion on Comparative Analysis of Dr. Bridge and Steel Beam Loss of MIDAS -Simply Supported Beam Computation with 20m Pretension Method%浅谈桥博与MIDAS之钢束损失比较分析—20m先张法简支梁计算

    Institute of Scientific and Technical Information of China (English)

    陈丽丽; 张明奇

    2012-01-01

    通过实际算例介绍了桥博与MIDAS作为桥梁专业通用性较强的软件,在钢束应力损失方面的计算结果的可靠性与差异。%With practical example, Dr. Bridge and MIDAS as software widely used in bridge major are intro- duced and the reliability and differences between them in computed results of steel beam stress loss are introduced as well.

  15. Observed Orbit Effects during Long Range Beam-Beam Studies

    CERN Document Server

    Alemany, R; Buffat, X; Calaga, R; Fitterer, M; Giachino, R; Hemelsoet, GH; Herr, W; Papotti, G; Pieloni, T; Poyer, M; Schaumann, M; Trad, G; Wollmann, D

    2012-01-01

    Possible limitations due to long range beam-beam effects at the LHC have been studied and are presented in this note. With a larger number of bunches and collisions in all interaction points, the crossing angles were reduced to enhance long range beam-beam effects. The analysis of the effects on the dynamic aperture and losses are documented in [1]. This note concentrates on the bunch-by-bunch orbit effects observed during the experiment.

  16. Measurements of aperture and beam lifetime using movable beam scrapers in Indus-2 electron storage ring.

    Science.gov (United States)

    Kumar, Pradeep; Ghodke, A D; Karnewar, A K; Holikatti, A C; Yadav, S; Puntambekar, T A; Singh, G; Singh, P

    2013-12-01

    In this paper, the measurements of vertical and horizontal aperture which are available for stable beam motion in Indus-2 at beam energy 2.5 GeV using movable beam scrapers are presented. These beam scrapers are installed in one of the long straight sections in the ring. With the movement of beam scrapers towards the beam centre, the beam lifetime is measured. The beam lifetime data obtained from the movement of vertical and horizontal beam scrapers are analyzed. The contribution of beam loss due to beam-gas scattering (vacuum lifetime) and electron-electron scattering within a beam bunch (Touschek lifetime) is separated from the measured beam lifetime at different positions of the beam scrapers. Vertical and horizontal beam sizes at scrapers location are estimated from the scraper movement towards the beam centre in quantum lifetime limit and their values closely agree with measured value obtained using X-ray diagnostic beamline.

  17. Measurements of aperture and beam lifetime using movable beam scrapers in Indus-2 electron storage ring

    Science.gov (United States)

    Kumar, Pradeep; Ghodke, A. D.; Karnewar, A. K.; Holikatti, A. C.; Yadav, S.; Puntambekar, T. A.; Singh, G.; Singh, P.

    2013-12-01

    In this paper, the measurements of vertical and horizontal aperture which are available for stable beam motion in Indus-2 at beam energy 2.5 GeV using movable beam scrapers are presented. These beam scrapers are installed in one of the long straight sections in the ring. With the movement of beam scrapers towards the beam centre, the beam lifetime is measured. The beam lifetime data obtained from the movement of vertical and horizontal beam scrapers are analyzed. The contribution of beam loss due to beam-gas scattering (vacuum lifetime) and electron-electron scattering within a beam bunch (Touschek lifetime) is separated from the measured beam lifetime at different positions of the beam scrapers. Vertical and horizontal beam sizes at scrapers location are estimated from the scraper movement towards the beam centre in quantum lifetime limit and their values closely agree with measured value obtained using X-ray diagnostic beamline.

  18. Determination of the topological charge of a twisted beam with a Fresnel bi-prism

    Science.gov (United States)

    Emile, Olivier; Emile, Janine; Brousseau, Christian

    2014-12-01

    The self-interference pattern of a Laguerre Gaussian beam using a Fresnel bi-prism is shown to be very different from what could be expected from a usual laser beam. It resembles the interference pattern that could be obtained using a double slit experiment. The interferences are shifted and the topological charge and its sign can be readily determined considering the shift order of the pattern only. However, since there is no diffraction nor absorption losses unlike in a double slit interference, such a set up could be used even for low power twisted beams or beams with high topological charge. Even fractional topological charges could be determined with an absolute precision of 0.05.

  19. Characteristics of microdomains and microdomain patterns recorded by electron beam irradiation on Y-cut LiNbO{sub 3} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kokhanchik, L. S. [Institute of Microelectronics Technology and High Purity Materials of the Russian Academy of Sciences, 142432 Chernogolovka, Moscow Region (Russian Federation); Gainutdinov, R. V.; Volk, T. R., E-mail: volk@ns.crys.ras.ru [Institute of Crystallography of the Russian Academy of Sciences, 119333 Moscow (Russian Federation); Lavrov, S. D. [Moscow State Institute of Radio Engineering, Electronics and Automation, 119454 Moscow (Russian Federation)

    2015-08-21

    We present the results of investigations of planar domain patterns (isolated domains and domain gratings) fabricated by irradiation of the nonpolar Y-surface of LiNbO{sub 3} crystals by an electron beam (EB) incident normally onto the surface. The EB recorded domains were investigated using atomic force microscopy, confocal second harmonic generation microscopy, and chemical etching as an auxiliary method. The dependence of the domain characteristics on irradiation conditions (acceleration voltage U, EB current I, and irradiation time t{sub irr}) were determined. The length L{sub d} of both isolated domains and domain gratings along the polar axis Z grows linearly with t{sub irr} (at U, I = const) with no tending to saturation. The plots L{sub d}(t{sub irr}) obtained for U = 10 and 15 kV are practically identical, whereas the values of L{sub d} for U = 5 kV are essentially lower. The domain thickness T{sub d} along the Y-direction, i.e., the depth of the switched layer grows with acceleration voltage U. These results are discussed in terms of space-charge fields formation arising under EB irradiation of insulators. The linearity of L{sub d}(t{sub irr}) is accounted for by the frontal domain growth via the viscous friction law. The experimental dependence of T{sub d} on U supports the suggestion that the domain thickness is determined by the penetration depth R{sub e} of primary electrons, which in turn is governed by U. The difference in L{sub d}(t{sub irr}) plots for different U is accounted for by different electron emission σ. Indirect evidences of a defect structure modification in a thin surface layer with respect to the crystal bulk are obtained.

  20. Characteristics of microdomains and microdomain patterns recorded by electron beam irradiation on Y-cut LiNbO3 crystals

    Science.gov (United States)

    Kokhanchik, L. S.; Gainutdinov, R. V.; Lavrov, S. D.; Volk, T. R.

    2015-08-01

    We present the results of investigations of planar domain patterns (isolated domains and domain gratings) fabricated by irradiation of the nonpolar Y-surface of LiNbO3 crystals by an electron beam (EB) incident normally onto the surface. The EB recorded domains were investigated using atomic force microscopy, confocal second harmonic generation microscopy, and chemical etching as an auxiliary method. The dependence of the domain characteristics on irradiation conditions (acceleration voltage U, EB current I, and irradiation time tirr) were determined. The length Ld of both isolated domains and domain gratings along the polar axis Z grows linearly with tirr (at U, I = const) with no tending to saturation. The plots Ld(tirr) obtained for U = 10 and 15 kV are practically identical, whereas the values of Ld for U = 5 kV are essentially lower. The domain thickness Td along the Y-direction, i.e., the depth of the switched layer grows with acceleration voltage U. These results are discussed in terms of space-charge fields formation arising under EB irradiation of insulators. The linearity of Ld(tirr) is accounted for by the frontal domain growth via the viscous friction law. The experimental dependence of Td on U supports the suggestion that the domain thickness is determined by the penetration depth Re of primary electrons, which in turn is governed by U. The difference in Ld(tirr) plots for different U is accounted for by different electron emission σ. Indirect evidences of a defect structure modification in a thin surface layer with respect to the crystal bulk are obtained.

  1. KEKB beam instrumentation systems

    Science.gov (United States)

    Arinaga, M.; Flanagan, J.; Hiramatsu, S.; Ieiri, T.; Ikeda, H.; Ishii, H.; Kikutani, E.; Mimashi, T.; Mitsuhashi, T.; Mizuno, H.; Mori, K.; Tejima, M.; Tobiyama, M.

    2003-02-01

    For the stable high-luminosity operation and luminosity increase, the electron and positron storage rings of the KEK B-Factory (KEKB) is equipped with various beam instrumentations, which have been working well since the start of the commissioning in December, 1998. Details and performance of the beam-position monitor system based on the spectrum analysis using DSPs, the turn-by-turn BPM with four-dimensional function available for measurements of the individual bunch position, phase and intensity, the parametric beam-DCCTs designed so as to avoid the magnetic-core-selection problems for the parametric flux modulation, the bunch-by-bunch feedback system indispensable to suppress the strong multibunch instabilities in KEKB, the various optical beam diagnostic systems, such as synchrotron radiation interferometers for precise beam-size measurement, the tune meters, the bunch length monitors and the beam-loss monitors are described. Delicate machine tuning of KEKB is strongly supported by these instrumentations.

  2. A crossed molecular beam and ab initio investigation of the exclusive methyl loss pathway in the gas phase reaction of boron monoxide (BO; X2Σ+) with dimethylacetylene (CH3CCCH3; X1A(1g)).

    Science.gov (United States)

    Kaiser, Ralf I; Maity, Surajit; Dangi, Beni B; Su, Yuan-Siang; Sun, B J; Chang, Agnes H H

    2014-01-21

    The crossed molecular beam reaction of boron monoxide ((11)BO; X(2)Σ(+)) with dimethylacetylene (CH3CCCH3; X(1)A(1g)) was investigated at a collision energy of 23.9 ± 1.5 kJ mol(-1). The scattering dynamics were suggested to be indirect (complex forming reaction) and were initiated by the addition of (11)BO(X(2)Σ(+)) with the radical center located at the boron atom to the π electron density at the acetylenic carbon-carbon triple bond without entrance barrier leading to cis-trans(11)BOC4H6 doublet radical intermediates. cis-(11)BOC4H6 underwent cis-trans isomerization followed by unimolecular decomposition via a methyl group (CH3) loss forming 1-propynyl boron monoxide (CH3CC(11)BO) in an overall exoergic reaction (experimental: -91 ± 22 kJ mol(-1); theoretical: -105 ± 9 kJ mol(-1); NIST: -104 ± 12 kJ mol(-1)) via a tight exit transition state; trans-(11)BOC4H6 was found to lose a methyl group instantaneously. Neither atomic nor molecular hydrogen loss pathways were detectable. The experimental finding of an exclusive methyl loss pathway gains full support from our computational study predicting a methyl group versus atomic hydrogen loss branching ratio of 99.99% to 0.01% forming 1-propynyl boron monoxide (CH3CC(11)BO) and 1-methyl-propadienyl boron monoxide (CH3((11)BO)CCCH2), respectively.

  3. Phenotypic plasticity of gas exchange pattern and water loss in Scarabaeus spretus (Coleoptera: Scarabaeidae): deconstructing the basis for metabolic rate variation.

    Science.gov (United States)

    Terblanche, John S; Clusella-Trullas, Susana; Chown, Steven L

    2010-09-01

    Investigation of gas exchange patterns and modulation of metabolism provide insight into metabolic control systems and evolution in diverse terrestrial environments. Variation in metabolic rate in response to environmental conditions has been explained largely in the context of two contrasting hypotheses, namely metabolic depression in response to stressful or resource-(e.g. water) limited conditions, or elevation of metabolism at low temperatures to sustain life in extreme conditions. To deconstruct the basis for metabolic rate changes in response to temperature variation, here we undertake a full factorial study investigating the longer- and short-term effects of temperature exposure on gas exchange patterns. We examined responses of traits of gas exchange [standard metabolic rate (SMR); discontinuous gas exchange (DGE) cycle frequency; cuticular, respiratory and total water loss rate (WLR)] to elucidate the magnitude and form of plastic responses in the dung beetle, Scarabaeus spretus. Results showed that short- and longer-term temperature variation generally have significant effects on SMR and WLR. Overall, acclimation to increased temperature led to a decline in SMR (from 0.071+/-0.004 ml CO(2) h(-1) in 15 degrees C-acclimated beetles to 0.039+/-0.004 ml CO(2) h(-1) in 25 degrees C-acclimated beetles measured at 20 degrees C) modulated by reduced DGE frequency (15 degrees C acclimation: 0.554+/-0.027 mHz, 20 degrees C acclimation: 0.257+/-0.030 mHz, 25 degrees C acclimation: 0.208+/-0.027 mHz recorded at 20 degrees C), reduced cuticular WLRs (from 1.058+/-0.537 mg h(-1) in 15 degrees C-acclimated beetles to 0.900+/-0.400 mg h(-1) in 25 degrees C-acclimated beetles measured at 20 degrees C) and reduced total WLR (from 4.2+/-0.5 mg h(-1) in 15 degrees C-acclimated beetles to 3.1+/-0.5 mg h(-1) in 25 degrees C-acclimated beetles measured at 25 degrees C). Respiratory WLR was reduced from 2.25+/-0.40 mg h(-1) in 15 degrees C-acclimated beetles to 1.60+/-0.40 mg h

  4. Beam-beam observations in the Relativistic Heavy Ion Collider

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Y. [Brookhaven National Laboratory (BNL), Upton, NY (United States); Fischer, W. [Brookhaven National Laboratory (BNL), Upton, NY (United States); White, S. [Brookhaven National Laboratory (BNL), Upton, NY (United States)

    2015-06-24

    The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been operating since 2000. Over the past decade, thanks to the continuously increased bunch intensity and reduced β*s at the interaction points, the maximum peak luminosity in the polarized proton operation has been increased by more than two orders of magnitude. In this article, we first present the beam-beam observations in the previous RHIC polarized proton runs. Then we analyze the mechanisms for the beam loss and emittance growth in the presence of beam-beam interaction. The operational challenges and limitations imposed by beam-beam interaction and their remedies are also presented. In the end, we briefly introduce head-on beam-beam compensation with electron lenses in RHIC.

  5. Hearing loss

    Science.gov (United States)

    Decreased hearing; Deafness; Loss of hearing; Conductive hearing loss; Sensorineural hearing loss; Presbycusis ... Symptoms of hearing loss may include: Certain sounds seeming too ... conversations when two or more people are talking Difficulty ...

  6. 金刚石探测器用于C-ADS注入器Ⅱ束损探测的模拟研究%Simulation of the Diamond Detector for the C-ADS Injector II Beam Loss Detection

    Institute of Scientific and Technical Information of China (English)

    左伟; 付鑫; 苏有武; 庞成果; 李武元; 徐俊奎; 李宗强; 毛旺; 严维伟; 徐翀

    2016-01-01

    The Chinese Accelerator Driven Subcritical System (C-ADS) injector II consists of super-conduction accelerating section which is half wave resonator (HWR), the designed beam intensity is 10 mA. To avoid the damage to the resonator due to proton beam loss, special Beam Loss Monitor (BLM) system is essential. BLM system could provide alarm signal when high energy deposition occurs which may cause the resonator quenching. Radiation field of 10 MeV proton lost at different point of the HWR are simulated with MCNPX, BLM could be set at proper positions based on the simulation. Considering the structure of HWR and the BLM detector selecting influence factor, radiation energy deposition in the diamond detector are simulated with MCNPX when the proton incidence angle change from 1°∼5°, Possible beam loss point can be deduced from the relationship of energy deposition in detectors at different locations. The results indicate that energy spectra of secondary particles are independent with incidence angle;the number of secondary particles may be influenced slightly.%加速器驱动次临界系统C-ADS注入器Ⅱ采用强流超导质子直线加速器,设计流强达到10 mA。强流质子束产生的束流损失有可能损伤超导腔,需要专用的束流损失监测系统进行监测,束流损失探测器(BLM)需要在高能量沉积导致超导腔失超之前提供警报。通过MCNPX模拟计算10 MeV质子在半波谐振腔(HWR)不同位置损失产生的辐射场,比较选取超导腔管道进出口处4个位置为推荐束损探测器放置的位置,结合HWR腔结构和束损探测器选择的影响因素,计算了次级辐射在金刚石探测器中的能量沉积以及1°∼5°不同质子入射角度对探测的影响。结果表明,根据不同位置处探测器的能量沉积关系可以推断出束损点;不同入射角度不会影响生成粒子的能量分布,只轻微影响生成粒子的数目。

  7. ADT fast losses MD

    CERN Document Server

    Priebe, A; Dehning, B; Redaelli, S; Salvachua Ferrando, BM; Sapinski, M; Solfaroli Camillocci, M; Valuch, D

    2013-01-01

    The fast beam losses in the order of 1 ms are expected to be a potential major luminosity limitation for higher beam energies after the LHC long shutdown (LS1). Therefore a Quench Test is planned in the winter 2013 to estimate the quench limit in this timescale and revise the current models. This experiment was devoted to determination the LHC Transverse Damper (ADT) as a system for fast losses induction. A non-standard operation of the ADT was used to develop the beam oscillation instead of suppressing them. The sign flip method had allowed us to create the fast losses within several LHC turns at 450 GeV during the previous test (26th March 2012). Thus, the ADT could be potentially used for the studies of the UFO ("Unidentied Falling Object") impact on the cold magnets. Verification of the system capability and investigations of the disturbed beam properties were the main objectives of this MD. During the experiment, the pilot bunches of proton beam were excited independently in the horizontal and vertical ...

  8. Structure of the runaway electron loss during induced disruptions in TEXTOR

    Science.gov (United States)

    Wongrach, K.; Finken, K. H.; Abdullaev, S. S.; Willi, O.; Zeng, L.; Xu, Y.

    2015-10-01

    The loss of runaway electrons during an induced disruption is recorded by a synchrotron imaging technique using a fast infrared CCD camera. The loss is predominantly diffuse. During the "spiky-loss phase", when the runaway beam moves close to the wall, a narrow channel between the runaway column and a scintillator probe is formed and lasts until the runaway beam is terminated. In some cases, the processed images show a stripe pattern at the plasma edge. A comparison between the MHD dominated disruptions and the MHD-free disruption is performed. A new mechanism of plasma disruptions with the runaway electron generation and a novel model which reproduces many characteristic features of the plasma beam evolution during a disruption is briefly described.

  9. Structure of the runaway electron loss during induced disruptions in TEXTOR

    Energy Technology Data Exchange (ETDEWEB)

    Wongrach, K.; Finken, K. H.; Willi, O. [Institut für Laser- und Plasmaphysik, Heinrich-Heine Universität Düsseldorf, Düsseldorf 40225 (Germany); Abdullaev, S. S. [Institut für Energie- und Klimaforschung, Forschungszentrum Jülich GmbH, Jülich 52428 (Germany); Zeng, L. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Xu, Y. [Southwestern Institute of Physics, Chengdu 610041 (China)

    2015-10-15

    The loss of runaway electrons during an induced disruption is recorded by a synchrotron imaging technique using a fast infrared CCD camera. The loss is predominantly diffuse. During the “spiky-loss phase”, when the runaway beam moves close to the wall, a narrow channel between the runaway column and a scintillator probe is formed and lasts until the runaway beam is terminated. In some cases, the processed images show a stripe pattern at the plasma edge. A comparison between the MHD dominated disruptions and the MHD-free disruption is performed. A new mechanism of plasma disruptions with the runaway electron generation and a novel model which reproduces many characteristic features of the plasma beam evolution during a disruption is briefly described.

  10. BEAM CONTAINMENT SYSTEM FOR NSLS-II

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, S.L.; Casey, W.; Job, P.K.

    2010-05-23

    The shielding design for the NSLS-II will provide adequate protection for the full injected beam loss in two periods of the ring around the injection point, but the remainder of the ring is shielded for lower losses of {le} 10% full beam. This will require a system to insure that beam losses don't exceed these levels for a period of time that could cause excessive radiation levels outside the shield walls. This beam containment system will measure, provide a level of control and alarm indication of the beam power losses along the beam path from the source (e-gun, linac) thru the injection system and the storage ring. This system will consist of collimators that will provide limits to (and potentially to measure) the beam miss-steering and control the loss points of the charge and monitors that will measure the average beam current losses along the beam path and alarm when this beam power loss exceeds the level set by the shielding specifications. This will require some new ideas in beam loss detection capability and collimation. The initial planning and R&D program will be presented.

  11. 部分相干平顶光束在增益或损耗介质中传输的M~2因子%M~2-factor of partially coherent flat-top beams propagating in gain or loss media

    Institute of Scientific and Technical Information of China (English)

    李高清; 付文羽

    2009-01-01

    根据光束在介质中传输强度二阶矩计算公式,推导出部分相干平顶光束在增益或损耗介质中传输的M~2因子解析表达式,并将高斯-谢尔模型光束在增益或损耗介质中的传输作为特例统一于一般表达式中.研究结果表明:部分相干平顶光束在增益或损耗介质中传输时的M~2因子与光束传输距离、光束相干长度、光束阶数及介质的特性有关.光束在增益或损耗介质中传输的这种特性为应用和控制光束传输提供了理论依据.%According to the second-order moments intensity formula of the beam propagating in the gain or loss media, an analytical expression for M~2-factor of partially coherent flat-top beams propagating in the media is derived, and Gaussian-Schell model beams propagation in gain or loss media, which is taken as a particular case, is integrated into a common expression. The research result shows that the M~2-factor of partially coherent flat-top beams propagating in the gain or loss media is relative to the propagation distance, the coherent length, the order of the beams and the character of media. The propagation characteristic of the beams propagating in the gain or loss media provides a theoretical basis for the application and control of the beam propagation.

  12. Simple process-based simulators for generating spatial patterns of habitat loss and fragmentation: a review and introduction to the G-RaFFe model.

    Science.gov (United States)

    Pe'er, Guy; Zurita, Gustavo A; Schober, Lucia; Bellocq, Maria I; Strer, Maximilian; Müller, Michael; Pütz, Sandro

    2013-01-01

    Landscape simulators are widely applied in landscape ecology for generating landscape patterns. These models can be divided into two categories: pattern-based models that generate spatial patterns irrespective of the processes that shape them, and process-based models that attempt to generate patterns based on the processes that shape them. The latter often tend toward complexity in an attempt to obtain high predictive precision, but are rarely used for generic or theoretical purposes. Here we show that a simple process-based simulator can generate a variety of spatial patterns including realistic ones, typifying landscapes fragmented by anthropogenic activities. The model "G-RaFFe" generates roads and fields to reproduce the processes in which forests are converted into arable lands. For a selected level of habitat cover, three factors dominate its outcomes: the number of roads (accessibility), maximum field size (accounting for land ownership patterns), and maximum field disconnection (which enables field to be detached from roads). We compared the performance of G-RaFFe to three other models: Simmap (neutral model), Qrule (fractal-based) and Dinamica EGO (with 4 model versions differing in complexity). A PCA-based analysis indicated G-RaFFe and Dinamica version 4 (most complex) to perform best in matching realistic spatial patterns, but an alternative analysis which considers model variability identified G-RaFFe and Qrule as performing best. We also found model performance to be affected by habitat cover and the actual land-uses, the latter reflecting on land ownership patterns. We suggest that simple process-based generators such as G-RaFFe can be used to generate spatial patterns as templates for theoretical analyses, as well as for gaining better understanding of the relation between spatial processes and patterns. We suggest caution in applying neutral or fractal-based approaches, since spatial patterns that typify anthropogenic landscapes are often non

  13. Hereditary Hearing Loss.

    Science.gov (United States)

    Tran, LenhAnh P.; Grundfast, Kenneth M.

    1997-01-01

    This article discusses inheritance patterns in hearing loss, epidemiology, clues to genetic causes, locating genes that cause hereditary disorders, genes related to hearing loss disorders in individuals with Usher syndrome, Waardenburg syndrome, Treacher-Collins syndrome, Branchio-oto-renal and Pendred syndromes, and the significance of finding…

  14. Differential DNA methylation patterns between high and low responders to a weight loss intervention in overweight or obese adolescents: the EVASYON study.

    Science.gov (United States)

    Moleres, Adriana; Campión, Javier; Milagro, Fermín I; Marcos, Ascensión; Campoy, Cristina; Garagorri, Jesús M; Gómez-Martínez, Sonia; Martínez, J Alfredo; Azcona-Sanjulián, M Cristina; Martí, Amelia

    2013-06-01

    In recent years, epigenetic markers emerged as a new tool to understand the influence of lifestyle factors on obesity phenotypes. Adolescence is considered an important epigenetic window over a human's lifetime. The objective of this work was to explore baseline changes in DNA methylation that could be associated with a better weight loss response after a multidisciplinary intervention program in Spanish obese or overweight adolescents. Overweight or obese adolescents (n=107) undergoing 10 wk of a multidisciplinary intervention for weight loss were assigned as high or low responders to the treatment. A methylation microarray was performed to search for baseline epigenetic differences between the 2 groups (12 subjects/group), and MALDI-TOF mass spectrometry was used to validate (n=107) relevant CpG sites and surrounding regions. After validation, 5 regions located in or near AQP9, DUSP22, HIPK3, TNNT1, and TNNI3 genes showed differential methylation levels between high and low responders to the multidisciplinary weight loss intervention. Moreover, a calculated methylation score was significantly associated with changes in weight, BMI-SDS, and body fat mass loss after the treatment. In summary, we have identified 5 DNA regions that are differentially methylated depending on weight loss response. These methylation changes may help to better understand the weight loss response in obese adolescents.

  15. A Comparison of Pattern of Pregnancy Loss in Women with Infertility Undergoing IVF and Women with Unexplained Recurrent Miscarriages Who Conceive Spontaneously

    Directory of Open Access Journals (Sweden)

    Vidya A. Tamhankar

    2015-01-01

    Full Text Available Objective. Women with infertility and recurrent miscarriages may have an overlapping etiology. The aim of this study was to compare the pregnancy loss in pregnancies after IVF treatment with spontaneous pregnancies in women with recurrent miscarriages and to assess differences related to cause of infertility. Methods. The outcome from 1220 IVF pregnancies (Group I was compared with 611 spontaneous pregnancies (Group II in women with recurrent miscarriages. Subgroup analysis was performed in Group I based on cause of infertility: tubal factor (392 pregnancies; male factor (610 pregnancies; and unexplained infertility (218 pregnancies. Results. The clinical pregnancy loss rate in Group I (14.3% was significantly lower than that of Group II (25.8%, p<0.001 and this was independent of the cause of infertility. However the timing of pregnancy loss was similar between Groups I and II. The clinical pregnancy loss rate in Group I was similar in different causes of infertility. Conclusions. The clinical pregnancy loss rate following IVF treatment is lower than that of women with unexplained recurrent miscarriages who conceived spontaneously. This difference persists whether the infertility is secondary to tubal factors, male factors, or unexplained cause.

  16. Results of long range beam-beam studies and observations during operation in the LHC

    CERN Document Server

    Alemany, R; Buffat, X; Calaga, R; Fitterer, M; Giachino, R; Hemelsoet, GH; Herr, W; Papotti, G; Pieloni, T; Poyer, M; Schaumann, M; Trad, G; Wollmann, D

    2011-01-01

    We studied possible limitations due to the long range beam-beam effects in the LHC. With a larger number of bunches and collisions in all interaction points, we have reduced the crossing angles to enhance long range beam-beam effects to evaluate their influence on dynamic aperture and losses. Experience from operation with reduced separation was analysed and provides additional evidence.

  17. Strengthening of RC Beams with Large Openings in Shear by CFRP Laminates: Experiment and 2D Nonlinear Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    S.C. Chin

    2012-05-01

    Full Text Available This study presents the experimental study and numerical analysis of Reinforced Concrete (RC beams with large square openings placed in the shear region, at a distance 0.5d and d away from the support, strengthened by Carbon Fiber Reinforced Polymer (CFRP laminates. This research aims to investigate the strength losses in RC beam due to the presence of large square openings placed at two different locations in shear region. Also, in order to re-gain the beam structural capacity loss due to the openings, strengthening by CFRP laminates around the openings were studied. A total of six RC beams were tested to failure under four point loading including control beams, un-strengthened and strengthened RC beams with large square openings in shear region at a distance 0.5d and d away from the support. The CFRP strengthening configuration considered in this study was a full wrapping system around the square openings. A nonlinear finite element program, ATENA was used to validate the results of the tested beams. Comparisons between the finite element predictions and experimental results in terms of crack patterns and load deflection relationships are presented. The crack pattern results of the finite element model show good agreement with the experimental data. The load midspan deflection curves of the finite element models exhibited a stiffer result compared to the experimental beams. The possible reason may be due to the perfect bond assumption between the concrete and steel reinforcement.

  18. Three-dimensional fabrication and characterisation of core-shell nano-columns using electron beam patterning of Ge-doped SiO2

    DEFF Research Database (Denmark)

    Gontard, Lionel C.; Jinschek, Joerg R.; Ou, Haiyan;

    2012-01-01

    A focused electron beam in a scanning transmission electron microscope (STEM) is used to create arrays of core-shell structures in a specimen of amorphous SiO2 doped with Ge. The same electron microscope is then used to measure the changes that occurred in the specimen in three dimensions using e...

  19. CSNS束流损失监控(BLM)系统电离室的改进%Improved Design and Construction of the Lonization Chamber for CSNS Beam Loss Monitor (BLM) System

    Institute of Scientific and Technical Information of China (English)

    赵中亮; 陈昌; 徐美杭; 田建民; 阮向东; 韩晨霞; 陈元柏; 徐韬光; 陆双桐

    2011-01-01

    Improved design and construction of the ionization chamber (IC) for CSNS and PA beam loss monitor (BLM) system is reported. The good plateau( ≥2 000 V) and the measurement range up to 3.6 × 105rad/h are obtained in the improved ionization chamber. All of these show us the performances of the improved ionization chamber can be satisfied for CSNS BLM application.%报道了中国散裂中子源工程(CSNS)和强流质子加速器(PA)柬流损失监控(BLM)系统的电离室的改进.对改进后的电离室测量得到,电离室有良好的坪特性(坪长≥2 000 V),测量的辐照剂量范围到3.6×10 5rad/h,高压加到3500 V仍能稳定工作.测量的结果表明电离室探头性能已能满足CSNS和PA对束流损失监控的性能需求.

  20. Using optical feedback to compensate for the reflection loss caused by partially reflecting mirror in laser power beaming%反馈弥补激光能量传输中部分反射镜反射损失

    Institute of Scientific and Technical Information of China (English)

    黄虎; 李滨; 尤政; 王巍

    2013-01-01

    The photocell is usually covered by a layer of partially reflecting mirror in laser power beaming, which is used to reflect partial laser light, control the light power of receiver in real time and adjust the beam pointing from transmitter to receiver. The partially reflecting mirror will decrease the power transmission efficiency. In this paper a method of optical feedback laser power beaming is presented, the theoretical model is established and the laser output power expression is derived. The expression shows that the optical feedback can reduce the laser threshold current and increase the laser output power. The laser threshold currents and output powers in feedback and non feedback conditions were measured in experiments. The experiment results show that in optical feedback condition the threshold current is reduced by 25% and the output power is increased by 10% at the driving current of 60mA compared with those in non feedback condition. In the experiment, the output powers in the conditions with feedback and without reflecting mirror were also measured. The results show that the optical feedback can reduce the reflection loss caused by reflecting mirror from 10% to 3% . The optical feedback laser power transmission method compensates the reflection loss of the reflecting mirror and improves the power transmission efficiency.%激光能量传输中的光电池表面通常覆盖有一层部分反射镜,用于产生反射光信号,实时控制接收端的光功率大小以及调整发射端和接收端的对准度.部分反射镜会降低能量传输效率,提出了一种反馈式能量传输方式,建立了理论模型,推导了激光器输出功率表达式.从表达式中可以发现反馈激光可降低激光器的阈值电流,提高激光器的输出功率.通过实验测量了反馈和无反馈时激光器的阈值电流和输出功率,实验结果表明相比较于无反馈情况,反馈作用使激光器的阈值电流降低了25%,驱动电流为60 m

  1. An Analysis of the Far-Field Radiation Pattern of the Ultraviolet Light-Emitting Diode (LED) Engin LZ4-00UA00 Diode with and without Beam Shaping Optics

    Science.gov (United States)

    2015-09-01

    5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Karl K Klett Jr 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7...light-emitting diode (LED), with and without beam shaping optics. This LED has 4 emitters arranged in a square pattern that are off-center from the...in this work that the spectra of the LED, the Lexan LS2 polycarbonate, and the ThorLabs FES0450, 450-nm shortpass filter are correct, as specified in

  2. BATMAN beam properties characterization by the beam emission spectroscopy diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Bonomo, F., E-mail: federica.bonomo@igi.cnr.it [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova (Italy); Istituto Gas Ionizzati - CNR, Corso Stati Uniti 4, 35127 Padova (Italy); Ruf, B.; Schiesko, L.; Fantz, U.; Franzen, P.; Riedl, R.; Wünderlich, D. [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Barbisan, M.; Pasqualotto, R.; Serianni, G. [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova (Italy); Cristofaro, S. [Universitá degli Studi di Padova, Via 8 Febbraio 2, 35122 Padova (Italy)

    2015-04-08

    The ITER neutral beam heating systems are based on the production and acceleration of negative ions (H/D) up to 1 MV. The requirements for the beam properties are strict: a low core beam divergence (< 0.4 °) together with a low source pressure (≤ 0.3 Pa) would permit to reduce the ion losses along the beamline, keeping the stripping particle losses below 30%. However, the attainment of such beam properties is not straightforward. At IPP, the negative ion source testbed BATMAN (BAvarian Test MAchine for Negative ions) allows for deepening the knowledge of the determination of the beam properties. One of the diagnostics routinely used to this purpose is the Beam Emission Spectroscopy (BES): the H{sub α} light emitted in the beam is detected and the corresponding spectra are evaluated to estimate the beam divergence and the stripping losses. The BES number of lines of sight in BATMAN has been recently increased: five horizontal lines of sight providing a vertical profile of the beam permit to characterize the negative ion beam properties in relation to the source parameters. Different methods of H{sub α} spectra analysis are here taken into account and compared for the estimation of the beam divergence and the amount of stripping. In particular, to thoroughly study the effect of the space charge compensation on the beam divergence, an additional hydrogen injection line has been added in the tank, which allows for setting different background pressure values (one order of magnitude, from about 0.04 Pa up to the source pressure) in the beam drift region.

  3. A crossed molecular beam and ab-initio investigation of the reaction of boron monoxide (BO; X2Σ+) with methylacetylene (CH3CCH; X1A1): competing atomic hydrogen and methyl loss pathways.

    Science.gov (United States)

    Maity, Surajit; Parker, Dorian S N; Dangi, Beni B; Kaiser, Ralf I; Fau, Stefan; Perera, Ajith; Bartlett, Rodney J

    2013-11-21

    The gas-phase reaction of boron monoxide ((11)BO; X(2)Σ(+)) with methylacetylene (CH3CCH; X(1)A1) was investigated experimentally using crossed molecular beam technique at a collision energy of 22.7 kJ mol(-1) and theoretically using state of the art electronic structure calculation, for the first time. The scattering dynamics were found to be indirect (complex forming reaction) and the reaction proceeded through the barrier-less formation of a van-der-Waals complex ((11)BOC3H4) followed by isomerization via the addition of (11)BO(X(2)Σ(+)) to the C1 and/or C2 carbon atom of methylacetylene through submerged barriers. The resulting (11)BOC3H4 doublet radical intermediates underwent unimolecular decomposition involving three competing reaction mechanisms via two distinct atomic hydrogen losses and a methyl group elimination. Utilizing partially deuterated methylacetylene reactants (CD3CCH; CH3CCD), we revealed that the initial addition of (11)BO(X(2)Σ(+)) to the C1 carbon atom of methylacetylene was followed by hydrogen loss from the acetylenic carbon atom (C1) and from the methyl group (C3) leading to 1-propynyl boron monoxide (CH3CC(11)BO) and propadienyl boron monoxide (CH2CCH(11)BO), respectively. Addition of (11)BO(X(2)Σ(+)) to the C1 of methylacetylene followed by the migration of the boronyl group to the C2 carbon atom and/or an initial addition of (11)BO(X(2)Σ(+)) to the sterically less accessible C2 carbon atom of methylacetylene was followed by loss of a methyl group leading to the ethynyl boron monoxide product (HCC(11)BO) in an overall exoergic reaction (78 ± 23 kJ mol(-1)). The branching ratios of these channels forming CH2CCH(11)BO, CH3CC(11)BO, and HCC(11)BO were derived to be 4 ± 3%, 40 ± 5%, and 56 ± 15%, respectively; these data are in excellent agreement with the calculated branching ratios using statistical RRKM theory yielding 1%, 38%, and 61%, respectively.

  4. 二维根尖周片与锥形束CT成像在牙周病理诊断中的运用比较%Detection of periodontal bone loss using cone beam CT and intraoral radiography

    Institute of Scientific and Technical Information of China (English)

    任迅

    2014-01-01

    目的:比较根尖周片与锥形束CT(Cone beam CT,CBCT)成像在牙周骨丧失中的检测与定位作用。方法:图像选自需进行牙周评价的患者牙片,样本共计51个测量位点,包括水平和垂直骨丧失,分别由三名检测者进行评价,主要通过测量骨丧失的线性高度、深度和宽度以及对X射线断层片上的联合骨缺损进行识别鉴定。结果:两种成像方式在定性骨缺损上差异无统计学意义(P>0.05),但在测量釉牙骨质界(CEJ)和牙槽脊顶(AC)间距离时两种成像方式差异有统计学意义(P0.05)。在本研究的39颗牙中,30.8%有联合骨缺损。结论:两种测量方式在测量牙槽脊的高度时有差异,但在测量骨缺失的深度和宽度时结论相似。应用CBCT 成像方式能对颊侧和舌侧/腭侧进行全面分析,并对骨缺失的表面形态进行观察。%To compare periapical radiographs with cone beam CT(CBCT) imaging in detecting and localizing alveolar bone loss by comparing linear measurements of the height, depth and width of the defects and identifying combined bone defects in tomographic images. Methods: The images were selected from a secondary database containing images of patients referred for periodontal evaluation. The sample consisted of 51 sites showing both horizontal and vertical bone loss, assessed by 3 trained examiners. Results: The results showed that there were no statisticaly significant differences between the imaging methods in terms of identification of the patern of bone loss. However, there were differences between the two methods when the distance between the cemento-enamel junction (CEJ) and the alveolar crest (AC) was measured. When the distance between the CEJ and the deepest point and width of the defect were measured, the methods showed no statisticaly significant difference. In this study, 30.8% of the 39 teeth evaluated had combined bone defects. Conclusions: The two methods

  5. Beam Interlocks for LHC and SPS

    CERN Document Server

    Dinius, A; Gimeno-Vicente, J; Nouchi, P; Puccio, B; Schmidt, R; Wenninger, J

    2003-01-01

    The Large Hadron Collider at CERN (LHC) will operate at 7 TeV/c with a luminosity of 10 cms. This requires two beams with about 3^10 protons/beam, corresponding to a stored energy of about 350 MJ, sufficient to heat and melt 500 kg of copper. Protection of equipment from damage in case of uncontrolled beam losses is challenging. Injection of the beam from the SPS to the LHC could already damage equipment and is only permitted when all LHC systems are correctly prepared. In case of an uncontrolled loss of the circulating LHC beams, it is required to extract the beams into a specially designed target as soon as possible. Beam loss monitors and equipment for hardware surveillance are distributed around the 26 km long accelerator. In case of failures or beam losses, the beam interlock system is informed and sends a dump request to the beam dumping system. The beam interlock system also inhibits injection when the LHC is not ready for beam. In this paper the requirements for the beam interlock system are discussed...

  6. BATMAN beam properties characterization by the beam emission spectroscopy diagnostic

    Science.gov (United States)

    Bonomo, F.; Ruf, B.; Barbisan, M.; Cristofaro, S.; Schiesko, L.; Fantz, U.; Franzen, P.; Pasqualotto, R.; Riedl, R.; Serianni, G.; Wünderlich, D.

    2015-04-01

    The ITER neutral beam heating systems are based on the production and acceleration of negative ions (H/D) up to 1 MV. The requirements for the beam properties are strict: a low core beam divergence (BATMAN (BAvarian Test MAchine for Negative ions) allows for deepening the knowledge of the determination of the beam properties. One of the diagnostics routinely used to this purpose is the Beam Emission Spectroscopy (BES): the Hα light emitted in the beam is detected and the corresponding spectra are evaluated to estimate the beam divergence and the stripping losses. The BES number of lines of sight in BATMAN has been recently increased: five horizontal lines of sight providing a vertical profile of the beam permit to characterize the negative ion beam properties in relation to the source parameters. Different methods of Hα spectra analysis are here taken into account and compared for the estimation of the beam divergence and the amount of stripping. In particular, to thoroughly study the effect of the space charge compensation on the beam divergence, an additional hydrogen injection line has been added in the tank, which allows for setting different background pressure values (one order of magnitude, from about 0.04 Pa up to the source pressure) in the beam drift region.

  7. E-beam inspection of EUV mask defects: To etch or not to etch?

    Science.gov (United States)

    Bonam, Ravi; Tien, Hung-Yu; Park, Chanro; Halle, Scott; Wang, Fei; Corliss, Daniel; Fang, Wei; Jau, Jack

    2014-04-01

    EUV Lithography is aimed to be inserted into mainstream production for sub-20nm pattern fabrication. Unlike conventional optical lithography, frequent defectivity monitors (adders, repeaters etc.) are required in EUV lithography. Due to sub-20nm pattern and defect dimensions e-beam inspection of critical pattern areas is essential for yield monitor. In previous work we showed sub-10nm defect detection sensitivity1 on patterned resist wafers. In this work we report 8-10× improvement in scan rates of etched patterns compared to resist patterns without loss in defect detection sensitivity. We observed good etch transfer of sub-10nm resist features. A combination of smart scan strategies with improved etched pattern scan rates can further improve throughput of e-beam inspection. An EUV programmed defect mask with Line/Space, Contact patterns was used to evaluate printability of defects and defect detection (Die-Die and Die-Database) capability of the e-beam inspection tool. Defect inspection tool parameters such as averaging, threshold value were varied to assess its detection capability and were compared to previously obtained results on resist patterns.

  8. Beam Diagnostics for the J-PARC Main Ring Synchrotron

    CERN Document Server

    Toyama, Takeshi; Hashimoto, Yoshinori; Hayashi, Naoki; Kishiro, Junichi; Lee, Seishu; Miura, Takako; Muto, Suguru; Toyokawa, Ryoji

    2005-01-01

    Beam diagnostics: beam intensity monitors (DCCT, SCT, FCT, WCM), beam position monitors (ESM), beam loss monitors (proportional chamber, air ion chamber), beam profile monitors (secondary electron emission, gas-sheet) have been designed, tested, and will be installed for the Main Ring synchrotron of J-PARC (Japan Proton Accelerator Research Complex). This paper describes the basic design principle and specification of each monitor, with a stress on how to cope with high power beam (average circulation current of ~12 A) and low beam loss operation (less than 1 W/m except a collimator region). Some results of preliminary performance test using present beams and a radiation source will be reported.

  9. Accelerator physics studies on the effects from an asynchronous beam dump onto the LHC experimental region collimators

    CERN Document Server

    Lari, L; Boccone, V; Bruce, R; Cerutti, F; Rossi, A; Vlachoudis, V; Mereghetti, A; Faus-Golfe, A

    2012-01-01

    Asynchronous beam aborts at the LHC are estimated to occur on average once per year. Accelerator physics studies of asynchronous dumps have been performed at different beam energies and beta-stars. The loss patterns are analyzed in order to identify the losses in particular on the Phase 1 Tertiary Collimators (TCT), since their tungsten-based active jaw insert has a lower damage threshold than the carbon-based other LHC collimators. Settings of the tilt angle of the TCTs are discussed with the aim of reducing the thermal loads on the TCT themselves.

  10. Spatial and temporal predictions of soil moisture patterns and evaporative losses using TOPMODEL and the GASFLUX model for an Alaskan catchment

    OpenAIRE

    Quinn, P. F.; Ostendorf, B; Beven, K.; Tenhunen, J.

    1998-01-01

    International audience; By using topographic indices as derived from a Digital Terrain Models (DTM), it is possible to represent the heterogeneity within a landscape. This heterogeneity can reflect both long term evolutionary patterns seen in a landscape and the short term forcing of flow dynamics during storm events. By spatial analysis, the linkage between the geomorphological- hydrological-plant physiological phenomena can be examined. In this study, a direct link will be established betwe...

  11. Optimization of Land Use Pattern Reduces Surface Runoff and Sediment Loss in a Hilly-Gully Watershed at the Loess Plateau, China

    Directory of Open Access Journals (Sweden)

    Han Yini

    2016-04-01

    Full Text Available Aim of study: The aim is to find a way increasing gain yield and lessen area of farmland, and then increasing vegetation cover, improving environment and alleviating soil erosion.Area of study: The Hilly-Gully region at the loess plateau of China.Material and methods: In this study, an adjusted and optimized land use pattern was developed in Luoyugou watershed in the Yellow River valley based on the gradient distribution of land use types, and its effect on water and sediment transport was simulated using the SWAT model and GIS, with remote sensing images, land use maps and hydrologic data.Main results: The results indicate: average simulated runoff and sediment for the period 1986-2000 under conditions of the three land use pattern (2011, 2008 and optimized land use reduced by 0.002-0.013 m3/s (2.7-17.6% and 0.66 million tons, respectively. The runoff and sediment data obtained were compared with observed data from 2008, which showed that runoff and sediment production would be reduced by 467625 m3 and 22754 tons, respectively.Research highlights: The adjustment of the land use pattern in comprehensive consideration of vegetation and geography have a positive effect on water and sediment transport which will be important for decision making and water resources management, and provides a reference for future environmental management and ecological construction in the loess plateau Hilly-Gully region. 

  12. Mutation of the zebrafish glass onion locus causes early cell-nonautonomous loss of neuroepithelial integrity followed by severe neuronal patterning defects in the retina.

    Science.gov (United States)

    Pujic, Z; Malicki, J

    2001-06-15

    Mutation of the glass onion locus causes drastic neuronal patterning defects in the zebrafish retina and brain. The precise stratified appearance of the wild-type retina is absent in the mutants. The glass onion phenotype is first visible shortly after the formation of optic primordia and is characterized by the rounding of cells and disruption of the ventricular surface in the eye and brain neuroepithelia. With exception of the dorsal- and ventral-most regions of the brain, neuroepithelial cells lose their integrity and begin to distribute ectopically. At later stages, the laminar patterning of retinal neurons is severely disrupted. Despite the lack of lamination, individual retinal cell classes differentiate in the glass onion retina. Mosaic analysis reveals that the glass onion mutation acts cell nonautonomously within the retina and brain, as neuroepithelial cell morphology and polarity in these tissues are normal when mutant cells develop in wild-type hosts. We conclude that the glass onion mutation affects cell-cell signaling event(s) involved in the maintenance of the neuroepithelial cell layer shortly after its formation. The disruption of neuroepithelial integrity may be the cause of the neuronal patterning defects following neurogenesis. In addition, the expression of the glass onion phenotype in a subset of neuroepithelial cells as well as its onset following the initial formation of the neuroepithelial sheets indicate the presence of genetically distinct temporal and spatial subdivisions in the development of this histologically uniform tissue.

  13. Epigenetic Changes in the Methylation Patterns of KCNQ1 and WT1 after a Weight Loss Intervention Program in Obese Stroke Patients.

    Science.gov (United States)

    Abete, Itziar; Gómez-Úriz, Ana M; Mansego, María L; De Arce, Ana; Goyenechea, Estíbaliz; Blázquez, Vanessa; Martínez-Zabaleta, Maria T; González-Muniesa, Pedro; López De Munain, Adolfo; Martínez, J Alfredo; Campión, Javier; Milagro, Fermin I

    2015-01-01

    Ischemic stroke patients often show high concentrations of circulating inflammatory markers that are associated with increased risk of recurrence. Epigenetic mechanisms could be involved in obesity, inflammation and stroke. The objective of this research was to investigate, in obese patients suffering a previous stroke, the effects of a nutritional program on anthropometric and biochemical variables, and on the methylation patterns of two stroke-related genes (KCNQ1: potassium channel, voltage gated KQT-like subfamily Q, member 1; and WT1: Wilms tumor 1). Twenty-two ischemic stroke patients were compared with a control group composed of eighteen obese subjects with similar age and body mass index ranges. Both groups followed a 20-week nutritional program based on an energy-restricted balanced diet with high adherence to the Mediterranean dietary pattern. The intervention significantly improved anthropometric and metabolic variables, such as the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and C-reactive protein concentration, in ischemic stroke patients, and was accompanied by changes in the methylation patterns of both stroke-related genes, which correlated with anthropometric and biochemical variables.

  14. Polarization losses in reflector antennas

    Science.gov (United States)

    Safak, M.; Yazgan, E.

    1985-08-01

    Various definitions for polarization-loss efficiency of Cassegrainian and front-fed reflectors are compared. The effects of flare angle, feed taper and the feed pattern asymmetry on the polarization-loss efficiency are investigated. The definitions based on aperture fields are shown to be inadequate and far fields must be used for calculating the polarization losses.

  15. Beam simulation studies of ECR beam extraction and low energy beam transport for FRIB.

    Science.gov (United States)

    Ren, Haitao; Pozdeyev, Eduard; Lund, Steven M; Machicoane, Guillaume; Wu, Xiaoyu; Morgan, Glenn

    2016-02-01

    To meet the beam power requirements of 400 kW at the fragmentation target for facility for Rare Isotope Beams (FRIB), simultaneous acceleration of two-charge states should be used for heavier ions. These intense multi-charged ion beams will be produced by a 28 GHz electron cyclotron resonance (ECR) ion source at a high voltage of 35 kV. After extraction, the ion beam will be pre-accelerated to 12 keV/u with a 50 kV platform, transported down to an achromatic charge state selection (CSS) system followed by a vertical transport line, and then injected into a radio frequency quadrupole accelerator. The TRACK code developed at ANL is used to perform the simulations of the ECR beam extraction and low energy beam transport for FRIB. In this study, we include the magnetic field of ECR ion source into simulations. Different initial beam conditions as well as different space charge neutralization levels are tested for the ECR beamline. The beam loss in CSS system and the corresponding protective measures are discussed. The detailed results about the beam dynamic simulation and beam loss in CSS system will be presented in this paper.

  16. Beam dynamics issues for linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Ruth, R.D.

    1987-09-01

    In this paper we discuss various beam dynamics issues for linear colliders. The emphasis is to explore beam dynamics effects which lead to an effective dilution of the emittance of the beam and thus to a loss of luminosity. These considerations lead to various tolerances which are evaluated for a particular parameter set.

  17. Oxide nanoparticle EUV resists: toward understanding the mechanism of positive and negative tone patterning

    KAUST Repository

    Chakrabarty, Souvik

    2013-04-01

    DUV, EUV and e-beam patterning of hybrid nanoparticle photoresists have been reported previously by Ober and coworkers. The present work explores the underlying mechanism that is responsible for the dual tone patterning capability of these photoresist materials. Spectroscopic results correlated with mass loss and dissolution studies suggest a ligand exchange mechanism responsible for altering the solubility between the exposed and unexposed regions. © 2013 SPIE.

  18. Nanoparticle Photoresists: Ligand Exchange as a New, Sensitive EUV Patterning Mechanism

    KAUST Repository

    Kryask, Marie

    2013-01-01

    Hybrid nanoparticle photoresists and their patterning using DUV, EUV, 193 nm lithography and e-beam lithography has been investigated and reported earlier. The nanoparticles have demonstrated very high EUV sensitivity and significant etch resistance compared to other standard photoresists. The current study aims at investigating and establishing the underlying mechanism for dual tone patterning of these nanoparticle photoresist systems. Infrared spectroscopy and UV absorbance studies supported by mass loss and dissolution studies support the current model. © 2013SPST.

  19. Effects of rainfall pattern and fertilizer nitrogen on nitrogen loss in bypass flow in vertisols at the onset of rain season under tropical environments

    Directory of Open Access Journals (Sweden)

    Owino C.O.

    2012-10-01

    Full Text Available Bypass flow is a major avenue of fertilizer nitrogen (N loss from Vertisols under environments characterized by alternating dry and wet seasons. The study quantified the effects of rainfall intensity and frequency, and fertilizer N source and rate on N content of bypass flow in a Vertisol. We carried out two experiments. Experiment I comprised of 2 wetting status, 2 rainfall intensities, and 3 N sources. Experiment II involved 3N sources, 3N rates, and 3 levels of rainfall frequencies. In both Experiments, bypass flow was collected, filtered and analyzed for mineral N content. Wetting soil with 30mm of precipitation in 1h before fertilizer application resulted in significantly (p<0.05 higher bypass flow and mineral N content than did the no-wetting treatments. Rainfall intensity and frequency, and N rate significantly (p<0.05 increased mineral-N recovered in the bypass flow. The 3 N sources used are susceptible to loss in bypass flow.

  20. Dynamic array generation and pattern formation for optical tweezers

    DEFF Research Database (Denmark)

    Mogensen, P.C.; Glückstad, J.

    2000-01-01

    The generalised phase contrast approach is used for the generation of optical arrays of arbitrary beam shape, suitable for applications in optical tweezers for the manipulation of biological specimens. This approach offers numerous advantages over current techniques involving the use of computer......-generated holograms or diffractive optical elements. We demonstrate a low-loss system for generating intensity patterns suitable for the trapping and manipulation of small particles or specimens....