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Sample records for include beam loss

  1. 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.

  2. 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.

  3. 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.

  4. PDX neutral-beam reionization losses

    International Nuclear Information System (INIS)

    Kugel, H.W.; Dylla, H.F.; Eubank, H.P.; Kozub, T.A.; Moore, R.; Schilling, G.; Stewart, L.D.; von Halle, A.; Williams, M.D.

    1982-02-01

    Reionization losses for 1.5 MW H 0 and 2 MW D 0 neutral beams injected into the PDX tokamak were studied using pressure gauges, photo-transistors, thermocouples, surface shielding, and surface sample analysis. Considerable outgassing of conventionally prepared 304SS ducts occurred during initial injections and gradually decreased with the cumulative absorption of beam power. Reionization power losses are presently about 5% in the ducts and about 12% total for a beamline including the duct. Present duct pressures are attributed primarily to gas from the ion source and neutralizer with much smaller contributions from residual wall desorption. Physical mechanisms for the observed duct outgassing are discussed

  5. 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.

  6. 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.

  7. Beam Cooling with ionisation losses

    CERN Document Server

    Rubbia, Carlo; Kadi, Y; Vlachoudis, V

    2006-01-01

    A novel type of particle "cooling", called Ionization Cooling, is applicable to slow (v of the order of 0.1c) ions stored in a small ring. The many traversals through a thin foil enhance the nuclear reaction probability, in a steady configuration in which ionisation losses are recovered at each turn by a RF-cavity. For a uniform target "foil" the longitudinal momentum spread diverges exponentially since faster (slower) particles ionise less (more) than the average. In order to "cool" also longitudinally, a chromaticity has to be introduced with a wedge shaped "foil". Multiple scattering and straggling are then "cooled" in all three dimensions, with a method similar to the one of synchrotron cooling, but valid for low energy ions. Particles then stably circulate in the beam indefinitely, until they undergo for instance nuclear processes in the thin target foil. This new method is under consideration for the nuclear production of a few MeV/A ion beams. Simple reactions, for instance Li 7 + D Li 8 + p, are more ...

  8. 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.

  9. 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...

  10. Beam Loss Monitoring for LHC Machine Protection

    Science.gov (United States)

    Holzer, Eva Barbara; Dehning, Bernd; Effnger, Ewald; Emery, Jonathan; Grishin, Viatcheslav; Hajdu, Csaba; Jackson, Stephen; Kurfuerst, Christoph; Marsili, Aurelien; Misiowiec, Marek; Nagel, Markus; Busto, Eduardo Nebot Del; Nordt, Annika; Roderick, Chris; Sapinski, Mariusz; Zamantzas, Christos

    The energy stored in the nominal LHC beams is two times 362 MJ, 100 times the energy of the Tevatron. As little as 1 mJ/cm3 deposited energy quenches a magnet at 7 TeV and 1 J/cm3 causes magnet damage. The beam dumps are the only places to safely dispose of this beam. One of the key systems for machine protection is the beam loss monitoring (BLM) system. About 3600 ionization chambers are installed at likely or critical loss locations around the LHC ring. The losses are integrated in 12 time intervals ranging from 40 μs to 84 s and compared to threshold values defined in 32 energy ranges. A beam abort is requested when potentially dangerous losses are detected or when any of the numerous internal system validation tests fails. In addition, loss data are used for machine set-up and operational verifications. The collimation system for example uses the loss data for set-up and regular performance verification. Commissioning and operational experience of the BLM are presented: The machine protection functionality of the BLM system has been fully reliable; the LHC availability has not been compromised by false beam aborts.

  11. Measuring beam losses in the THI project

    International Nuclear Information System (INIS)

    David, L.; Duneau, P.; Lecorche, E.; Lermine, P.; Lemaitre, E.; Ulrich, M.

    1997-01-01

    The goal of the THI project (High Intensity Transport) is to upgrade the GANIL facilities by increasing the beam by a factor of 15, at least for light ions. This higher intensity is required by the radioactive beam facility SPIRAL starting in September 1997, to generate the new nuclear species in the solid target-source (ISOL method). For the control system, the most important issues are now to tune the accelerators while minimizing the beam losses at each stage of acceleration and when not possible, to have a fast beam loss detection signal. This system is composed of probes which deliver a signal to stop the beam when there's too much intensity lost and when not, a logarithmic value of the beam intensity. These probes are linked to a front end VME crate on the network, and in the control room, on the workstations, a graphical user interface program displays the beam variations using logarithmic scales. This program is also used to center the beam while injecting in or ejecting from the main cyclotrons by tuning the steerers, the magnetic elements inside, and the electrostatic deflector to be able to separate and extract the last beam turn. (author)

  12. RHIC beam loss monitor system design

    International Nuclear Information System (INIS)

    Witkover, R.; Zitvogel, E.; Michnoff, R.

    1997-01-01

    The Beam Loss Monitor (BLM) System is designed to prevent the quenching of RHIC magnets due to beam loss, provide quantitative loss data, and the loss history in the event of a beam abort. The system uses 400 ion chambers of a modified Tevatron design. To satisfy fast (single turn) and slow (100 msec) loss beam criteria and provide sensitivity for studies measurements, a range of over 8 decades is needed. An RC pre-integrator reduces the dynamic range for a low current amplifier. This is digitized for data logging. The output is also applied to an analog multiplier which compensates the energy dependence, extending the range of the abort comparators. High and low pass filters separate the signal to dual comparators with independent programmable trip levels. Up to 64 channels, on 8 VME boards, are controlled by a micro-controller based VME module, decoupling it from the front-end computer (FEC) for real-time operation. Results with the detectors in the RHIC Sextant Test and the electronics in the AGS-to-RHIC (AtR) transfer line will be presented

  13. Diffraction measurements using the LHC Beam Loss Monitoring System

    Science.gov (United States)

    Kalliokoski, Matti

    2017-03-01

    The Beam Loss Monitoring (BLM) system of the Large Hadron Collider protects the machine from beam induced damage by measuring the absorbed dose rates of beam losses, and by triggering beam dump if the rates increase above the allowed threshold limits. Although the detection time scales are optimized for multi-turn losses, information on fast losses can be recovered from the loss data. In this paper, methods in using the BLM system in diffraction studies are discussed.

  14. AIP Diffraction measurements using the LHC Beam Loss Monitoring System

    CERN Document Server

    Kalliokoski, Matti

    2017-01-01

    The Beam Loss Monitoring (BLM) system of the Large Hadron Collider protects the machine from beam induced damage by measuring the absorbed dose rates of beam losses, and by triggering beam dump if the rates increase above the allowed threshold limits. Although the detection time scales are optimized for multi-turn losses, information on fast losses can be recovered from the loss data. In this paper, methods in using the BLM system in di ff raction studies are discussed.

  15. The AGS Booster beam loss monitor system

    International Nuclear Information System (INIS)

    Beadle, E.R.; Bennett, G.W.; Witkover, R.L.

    1991-01-01

    A beam loss monitor system has been developed for the Brookhaven National Laboratory Booster accelerator, and is designed for use with intensities of up to 1.5 x 10 13 protons and carbon to gold ions at 50-3 x 10 9 ions per pulse. This system is a significant advance over the present AGS system by improving the sensitivity, dynamic range, and data acquisition. In addition to the large dynamic range achievable, it is adaptively shifted when high losses are detected. The system uses up to 80 argon filled ion chambers as detectors, as well as newly designed electronics for processing and digitizing detector outputs. The hardware simultaneously integrates each detector output, interfaces to the beam interrupt systems, and digitizes all 80 channels to 21 bits at 170 KHz. This paper discuses the design, construction, and operation of the system. 4 refs., 2 figs

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

    CERN Multimedia

    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.

  17. 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.

  18. 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...

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

    International Nuclear Information System (INIS)

    Marsili, A.

    2012-01-01

    The goal of this work was to identify patterns in the beam loss profiles, both in their spatial distribution and time evolution. CERN's Large Hadron Collider (LHC) is the largest device 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, and contain the particles into two counter circulating beams which collide in four interaction points. CERN and the LHC will be described in chapter 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 could 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 3600 ionisation chambers are installed. Further challenges include the high dynamical range of losses (chamber currents ranging between 2 pA and 1 mA). The BLM system will be further described in chapter 2. The subject of this thesis is to study the loss patterns and nd the origin of the losses in a deterministic way, by comparing measured losses to well understood loss scenarios. This is done through a case study: different techniques were used on a restrained set of loss scenarios, as a proof of concept of the possibility to extract information from a loss profile. Finding the origin of the losses should allow acting in response. A justification of the doctoral work will be given at the end of chapter 2. This thesis will then focus on the theoretical understanding and the implementation of the decomposition of a measured loss profile as a linear combination of the reference scenarios; and the evaluation of

  20. 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...

  1. 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.

  2. Mitigation of numerical noise for beam loss simulations

    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.

  3. LTRACK: Beam-transport calculation including wakefield effects

    International Nuclear Information System (INIS)

    Chan, K.C.D.; Cooper, R.K.

    1988-01-01

    LTRACK is a first-order beam-transport code that includes wakefield effects up to quadrupole modes. This paper will introduce the readers to this computer code by describing the history, the method of calculations, and a brief summary of the input/output information. Future plans for the code will also be described

  4. Beam Loss Monitors for NSLS-II Storage Ring

    International Nuclear Information System (INIS)

    Kramer, S.L.; Cameron, P.

    2011-01-01

    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.

  5. 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...

  6. Losses on SPS flat bottom and beam loading with LHC beams

    CERN Document Server

    Bartosik, H; Cettour Cave, S; Cornelis, K; Damerau, H; Goddard, B; Kain, V; Lasheen, A; Rumolo, G; Shaposhnikova, E; Timko, H

    2017-01-01

    Losses at SPS flat bottom with the LHC proton beams hadbeen studied since the earliest days the LHC beams becameavailable in the SPS. Some of the loss mechanisms involvedcould be identified and over the years of operation with thenominal 25ns LHC beam, the losses could be gradually re-duced. Nevertheless, in machine studies with high intensity25ns LHC beams it is still observed that the transmissiondegrades with intensity. As summarised in this paper, a se-ries of studies have been performed in 2016 with the aim offurther characterising the loss mechanisms and eventuallyfinding mitigation measures in view of the LHC injectorupgrade project (LIU)

  7. Gas flow and related beam losses in the ITER neutral beam injector

    International Nuclear Information System (INIS)

    Krylov, A.; Hemsworth, R.S.

    2006-01-01

    The gas flow in the ITER neutral beam injectors has been studied using a 3D Monte-Carlo code to define a number of key parameters affecting the design and operation of the injector. This paper presents the results of calculations of the gas density in the two accelerator concepts presently considered as options for the ITER injectors, and the resultant stripping losses of the negative ions during their acceleration to 1 MeV. The sensitivity of the model to various parameters has been studied, including the gas temperature in the ion source and the subsequent accommodation by collisions with the accelerator structure, and the degree of dissociation of the D 2 or H 2 in the ion source, and subsequent recombination during collisions with the accelerator structure. Additionally the sensitivity of the losses to details of the beam source design and operating parameters are examined for the both accelerator concepts. (author)

  8. 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...

  9. Theory of suppression of loss cone instabilities by electron beams

    International Nuclear Information System (INIS)

    Sinha, A.; Sinha, M.

    1981-01-01

    A new mechanism for the suppression of Drift Cyclotron Loss Cone instabilities by electron beams injected along the field lines is given. The mechanism explains some of the recent observations. (author)

  10. Correlation of beam loss to residual activation in the AGS

    International Nuclear Information System (INIS)

    Brown, K.A.

    1991-01-01

    Studies of beam loss and activation at the AGS have provided a better understanding of measurements of beam loss and how they may be used to predict activation. Studies have been done in which first order correlations have been made between measured beam losses on the distributed ionization chamber system in the AGS and the health physics recorded residual activation. These studies have provided important insight into the ionization chamber system, its limitations, and its usefulness in the prediction of activation based on monitored beam loss. In recent years the AGS has run high intensity protons primarily for rare kaon decay experiments. In this mode of running the AGS typically accelerates beam from an injection momentum of 0.644 GeV/c up to a slow extracted beam (SEB) momentum of 24.2 GeV/c. The beam intensities are on the order of 4.5 x 10 13 protons per AGS cycle at injection to as high as 1.9 x 10 13 protons per AGS cycle at extraction. Residual activation varies around the AGS ring from the order of 5 mR/hour to levels of the order at 5 R/hour. The highest levels occur around the AGS beam catcher and the extraction equipment

  11. Correlation of beam loss to residual activation in the AGS

    International Nuclear Information System (INIS)

    Brown, K.A.

    1991-01-01

    Studies of beam loss and activation at the AGS have provided a better understanding of measurements of beam loss and how they may be used to predict activation. Studies have been done in which first order correlations have been made between measured beam losses on the distributed ionization chamber system in the AGS and the health physics recorded residual activation. These studies have provided important insight into the ionization chamber system, its limitations, and its usefulness in the prediction of activation based on monitored beam loss. In recent years the AGS has run high intensity protons primarily for rare known decay experiments. In this mode of running the AGS typically accelerates beam from an injection momentum of 0.644 GeV/c up to a slow extracted beam (SEB) momentum of 24.2 GeV/c. The beam intensities are on the order of 4.5 x 10 13 protons per AGS cycle at injection to as high as 1.9 x 10 13 protons per AGS cycle at extraction. Residual activation varies around the AGS ring from the order of 5 mR/hour to levels of the order at 5 R/hour. The highest levels occur around the AGS beam catcher and the extraction equipment. 7 refs., 3 figs., 2 tabs

  12. Tunable cavity resonator including a plurality of MEMS beams

    Science.gov (United States)

    Peroulis, Dimitrios; Fruehling, Adam; Small, Joshua Azariah; Liu, Xiaoguang; Irshad, Wasim; Arif, Muhammad Shoaib

    2015-10-20

    A tunable cavity resonator includes a substrate, a cap structure, and a tuning assembly. The cap structure extends from the substrate, and at least one of the substrate and the cap structure defines a resonator cavity. The tuning assembly is positioned at least partially within the resonator cavity. The tuning assembly includes a plurality of fixed-fixed MEMS beams configured for controllable movement relative to the substrate between an activated position and a deactivated position in order to tune a resonant frequency of the tunable cavity resonator.

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

    Directory of Open Access Journals (Sweden)

    Sergey S. Kurennoy

    1999-03-01

    Full Text Available 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.

  14. 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...

  15. 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. ...

  16. 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....

  17. Application of diamond based beam loss monitors at LHC

    International Nuclear Information System (INIS)

    Hempel, Maria

    2013-04-01

    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 the LHC, especially near each quadrupole and next to

  18. 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

  19. Consideration of neutral beam prompt loss in the design of a tokamak helicon antenna

    International Nuclear Information System (INIS)

    Pace, D.C.; Van Zeeland, M.A.; Fishler, B.; Murphy, C.

    2016-01-01

    Highlights: • Neutral beam prompt losses place appreciable power on an in-vessel tokamak antenna. • Simulations predict prompt loss power and inform protective tile design. • Experiments confirm the validity of the prompt loss simulations. - Abstract: Neutral beam prompt losses (injected neutrals that ionize such that their first poloidal transit intersects with the wall) can put appreciable power on the outer wall of tokamaks, and this power may damage the wall or other internal components. These prompt losses are simulated including a protruding helicon antenna installation in the DIII-D tokamak and it is determined that 160 kW of power will impact the antenna during the injection of a particular neutral beam. Protective graphite tiles are designed in response to this modeling and the wall shape of the installed antenna is precisely measured to improve the accuracy of these calculations. Initial experiments confirm that the antenna component temperature increases according to the amount of neutral beam energy injected into the plasma. In this case, only injection of beams that are aimed counter to the plasma current produce an appreciable power load on the outer wall, suggesting that the effect is of little concern for tokamaks featuring only co-current neutral beam injection. Incorporating neutral beam prompt loss considerations into the design of this in-vessel component serves to ensure that adequate protection or cooling is provided.

  20. 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...

  1. 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...

  2. 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.

  3. 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...

  4. Implementation of Beam-Loss Monitor systems for the SSC

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, R.G.

    1994-07-01

    Beam-Loss Monitors (BLM) are used with each accelerator in the Superconducting Super Collider complex. The primary purpose of these detectors is to protect the accelerators from damage due to the loss of protons. Although the range of primary beam energies to be covered is very large, 20 MeV to 20 TeV, we plan to maintain commonality of detectors and electronics as much as possible. In this report the plans for developing and implementing BLM systems for each of the accelerators will be discussed. Possible solutions to problems that have been identified are presented.

  5. 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.

  6. 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...

  7. Beam Loss Simulation Studies for ALS Top-Off Operation

    CERN Document Server

    Nishimura, Hiroshi; Robin, David; Steier, Christoph

    2005-01-01

    The ALS is planning to operate with top-off injection at higher beam currents and smaller vertical beam size. As part of a radiation safety study for top-off, we carried out two kinds of tracking studies: (1) to confirm that the injected beam cannot go into users' photon beam lines, and (2) to control the location of beam dump when the storage ring RF is tripped. (1) is done by tracking electrons from a photon beam line to the injection sector inversely by including the magnetic field profiles, varying the field strength with geometric aperture limits to conclude that it is impossible. (2) is done by tracking an electron with radiation in the 6-dim space for different combinations of vertical scrapers for the realistic lattice with errors.

  8. Long radiation detector system for beam loss monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Balsamo, J.; Fewell, N.M.; Klein, J.D.; Witkover, R.L.

    1977-01-01

    The Long Radiation Monitor (LRM) system installed at the 200 MeV linac at Brookhaven National Laboratory is described. This system allows observation of both the spatial and temporal character of the losses in the linac and its transport lines. An array of large diameter gas filled coaxial cables are used as extended ion chambers to detect the losses. The output signals are available as a histogram, video waveforms, and numerical data via the computer. A fast beam interrupt is also provided. The detector characteristics and details of the processing electronics are presented. Results of studies of longitudinal, steering and focusing losses are described.

  9. Long radiation detector system for beam loss monitoring

    International Nuclear Information System (INIS)

    Balsamo, J.; Fewell, N.M.; Klein, J.D.; Witkover, R.L.

    1977-01-01

    The Long Radiation Monitor (LRM) system installed at the 200 MeV linac at Brookhaven National Laboratory is described. This system allows observation of both the spatial and temporal character of the losses in the linac and its transport lines. An array of large diameter gas filled coaxial cables are used as extended ion chambers to detect the losses. The output signals are available as a histogram, video waveforms, and numerical data via the computer. A fast beam interrupt is also provided. The detector characteristics and details of the processing electronics are presented. Results of studies of longitudinal, steering and focusing losses are described

  10. Beam loss control on the ISIS synchrotron simulations, measurements, upgrades

    CERN Document Server

    Warsop, C M

    2003-01-01

    The ISIS 800 MeV proton synchrotron presently provides 2.5*10/sup 13/ protons per pulse at 50 Hz, corresponding to a mean power of 160 kW. A dual harmonic RF system upgrade, now being installed, is expected to increase the intensity and power to about 3.75*10/sup 13/ ppp and 240 kW respectively. This paper describes work presently underway to understand and optimise beam loss control, which is a dominant factor determining operational performance. The main features of the collimation system are described, and Monte Carlo simulations of the loss control process are used to understand variations of efficiency with beam loss mode (growth rate, plane). Results of simulations are compared with measurements and operational data. Improvements to measurements are also outlined.

  11. 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...

  12. 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...

  13. 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.

  14. 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...

  15. 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

  16. Beam Losses and Lifetime of the LHC Beam in the SPS

    CERN Document Server

    Bohl, T; Shaposhnikova, Elena; Tückmantel, Joachim

    2006-01-01

    Studies of the LHC beam loss in the SPS started in 2003 [1], [2] and continued in 2004. The flat bottom losses strongly depend on the batch intensity and the RF voltage. For beam with the 75 ns spacing at the same bunch intensity they are smaller than for the 25 ns spaced bunches. Large voltage on the flat bottom together with some optimum voltage at injection helps to reduce losses. Analysis of data from 2003 has shown that observations are compatible with a diffusion like process on the flat bottom. Therefore significant time during 2004 was devoted to studies of possible RF noise sources. However the main improvement in beam lifetime on the flat bottom was observed after a change in the working point in the transverse plane (MD on 1.09.2004). In this Note we present measurements of beam loss and lifetime done during several dedicated SPS MDs for different conditions in the ring. Analysis of beam coasts will be presented separately.

  17. Examination of the CLIC drive beam pipe design for thermal distortion caused by distributed beam loss

    CERN Document Server

    Johnson, C D

    1997-01-01

    Beam transport programs are widely used to estimate the distribution of power deposited in accelerator structures by particle beams, either intentionally as for targets or beam dumps or accidentally owing to beam loss incidents. While this is usually adequate for considerations of radiation safety, it does not reveal the expected temperature rise and its effect on structural integrity. To find this, thermal diffusion must be taken into account, requiring another step in the analysis. The method that has been proposed is to use the output of a transport program, perhaps modified, as input for a finite element analysis program that can solve the thermal diffusion equation. At CERN, the design of the CLIC drive beam pipe has been treated in this fashion. The power distribution produced in the walls by a distributed beam loss was found using the electron gamma shower code EGS4. The distribution of power density was then used to form the input for the finite element analysis program ANSYS, which was able to find t...

  18. 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...

  19. 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

  20. 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.

  1. A semi-discretized thin-walled beam element including distortion

    DEFF Research Database (Denmark)

    Andreassen, Michael Joachim; Jönsson, Jeppe

    2013-01-01

    An advanced thin-walled beam element including distortion of the cross section is presented. The formulation is based on a generalization of the classical Vlasov beam theory for analysis of open and closed thin-walled cross sections by including distortional displacements.The beam element...... formulation utilizes a semidiscretization approach in which the cross section is discretized into wall elements and the analytical solutions of the related GBT beam equations are used as displacement functions in the axial direction. Thus the beam element contains the semi-analytical solutions. In a number...... of related publications the authors have recently presented the semi-discretization approach and the analytical solution of the generalized beam equations. An illustrative example showing the validity and the accuracy of the developed distortional semi-discretized thin-walled beam element is given...

  2. Beam loss due to the aperture limitation resulting from intrabeam scattering

    International Nuclear Information System (INIS)

    Lee, S.Y.

    1984-01-01

    Diffusion equation is used to evaluate the beam loss in the presence of aperture limitation resulting from the intrabeam scattering. We discuss the effect of different boundary conditions. Satisfactory beam intensity can be maintained within the proposed RHIC operation time

  3. Loss of Energy Concentration in Nonlinear Evolution Beam Equations

    Science.gov (United States)

    Garrione, Maurizio; Gazzola, Filippo

    2017-12-01

    Motivated by the oscillations that were seen at the Tacoma Narrows Bridge, we introduce the notion of solutions with a prevailing mode for the nonlinear evolution beam equation u_{tt} + u_{xxxx} + f(u)= g(x, t) in bounded space-time intervals. We give a new definition of instability for these particular solutions, based on the loss of energy concentration on their prevailing mode. We distinguish between two different forms of energy transfer, one physiological (unavoidable and depending on the nonlinearity) and one due to the insurgence of instability. We then prove a theoretical result allowing to reduce the study of this kind of infinite-dimensional stability to that of a finite-dimensional approximation. With this background, we study the occurrence of instability for three different kinds of nonlinearities f and for some forcing terms g, highlighting some of their structural properties and performing some numerical simulations.

  4. 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.

  5. Transient beam losses in the LHC injection kickers from micron scale dust particles

    CERN Document Server

    Goddard, B; Baer, T; Barnes, M J; Cerutti, F; Ferrari, A; Garrel, N; Gerardin, A; Guinchard, M; Lechner, A; Masi, A; Mertens, V; Morón Ballester, R; Redaelli, S; Uythoven, J; Vlachoudis, V; Zimmermann, F

    2012-01-01

    Transient beam losses on a time scale of a few ms have been observed in the LHC injection kickers, occurring mainly shortly after beam injection with a strong correlation in time to the kicker pulsing. The beam losses, which have at times affected LHC availability, are attributed to micron scale ceramic dust particles detached from the alumina beam pipe and accelerated into the beam. The beam related observations are described, together with laboratory measurements of beam pipe contamination and kicker vibration, simulations of electric field in the beam pipe and the basic dynamic model. Energy deposition simulations modelling the beam losses are presented and compared to measurement. Extrapolations to future LHC operation at higher intensities and energies are made, and prospects for mitigation are discussed.

  6. 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...

  7. 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...

  8. PTEN loss and p27 loss differ among morphologic patterns of prostate cancer, including cribriform.

    Science.gov (United States)

    Ronen, Shira; Abbott, Daniel W; Kravtsov, Oleksandr; Abdelkader, Amrou; Xu, Yayun; Banerjee, Anjishnu; Iczkowski, Kenneth A

    2017-07-01

    The presence and extent of cribriform pattern of prostate cancer portend recurrence and cancer death. The relative expressions within this morphology of the prognostically adverse loss of PTEN, and the downstream inactivation of cell cycle inhibitor p27/Kip1 had been uncertain. In this study, we examined 52 cases of cribriform cancer by immunohistochemistry for PTEN, p27, and CD44 variant (v)7/8, and a subset of 17 cases by chromogenic in situ hybridization (ISH) using probes for PTEN or CDKN1B (gene for p27). The fractions of epithelial pixels positive by immunohistochemistry and ISH were digitally assessed for benign acini, high-grade prostatic intraepithelial neoplasia, and 8 morphologic patterns of cancer. Immunostaining results demonstrated that (1) PTEN loss was significant for fused small acini, cribriform-central cells, small cribriform acini, and Gleason grade 5 cells in comparison with other acini; (2) p27 loss was significant only for cribriform-peripheral cells and borderline significant for fused small acini in comparison with benign acini; and (3) CD44v7/8 showed expression loss in cribriform-peripheral cells; other comparisons were not significant. ISH showed that cribriform cancer had significant PTEN loss normalized to benign acini (PPTEN or p27 loss as prognostic factors demands distinct assessment in the varieties of Gleason 4 cancer, and in the biphenotypic peripheral versus central populations in cribriform structures. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Functional and Linearity test system for the LHC Beam Loss Monitoring data acquisition card

    CERN Document Server

    Emery, Jonathan; Effinger, E; Leitner, R; Zamantzas, C

    2007-01-01

    In the frame of the design and development of the beam loss monitoring (BLM) system for the Large Hadron Collider (LHC) a flexible test system has been developed to qualify and verify during design and production the BLM LHC data acquisition card. It permits to test completely the functionalities of the board as well as realizing analog input signal generation to the acquisition card. The system utilize two optical receivers, a Field Programmable Gate Array (FPGA), eights flexible current sources and a Universal Serial Bus (USB) to link it to a PC where a software written in LabWindows/CVI© (National Instruments) runs. It includes an important part of the measurement processing developed for the BLM in the future LHC accelerator. It is called Beam Loss Electronic Current to Frequency Tester (BLECFT).

  10. Studies of Limits on Uncontrolled Heavy Ion Beam Losses for Allowing Hands-On Maintenance

    Energy Technology Data Exchange (ETDEWEB)

    Reginald M. Ronningen; Igor Remec

    2010-09-11

    Dose rates from accelerator components activated by 1 W/m beam losses are obtained semiempirically for a 1 GeV proton beam and by use of Monte Carlo transport codes for the proton beam and for 777 MeV/u 3He, 500 MeV/u 48Ca, 86Kr, 136Xe, and 400 MeV/u 238U ions. The dose rate obtained by the semi-empirical method, 0.99 mSv/h (99 mrem/h) at 30 cm, 4 h after 100 d irradiation by a 1-GeV proton beam, is consistent with studies at several accelerator facilities and with adopted hands-on maintenance dose rate limits. Monte Carlo simulations verify this result for protons and extend studies to heavy ion beam losses in drift-tube linac and superconducting linac accelerating structures. The studies indicate that the 1 W/m limit imposed on uncontrolled beam losses for high-energy proton beams might be relaxed for heavy ion beams. These studies further suggest that using the ratio of neutrons produced by a heavy ion beam to neutrons produced by a proton beam along with the dose rate from the proton beam (for thin-target scenarios) should allow an estimate of the dose rates expected from heavy ion beam losses.

  11. 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...

  12. Numerical Acoustic Models Including Viscous and Thermal losses: Review of Existing and New Methods

    DEFF Research Database (Denmark)

    Andersen, Peter Risby; Cutanda Henriquez, Vicente; Aage, Niels

    2017-01-01

    This work presents an updated overview of numerical methods including acoustic viscous and thermal losses. Numerical modelling of viscothermal losses has gradually become more important due to the general trend of making acoustic devices smaller. Not including viscothermal acoustic losses...... in such numerical computations will therefore lead to inaccurate or even wrong results. Both, Finite Element Method (FEM) and Boundary Element Method (BEM), formulations are available that incorporate these loss mechanisms. Including viscothermal losses in FEM computations can be computationally very demanding, due...... and BEM method including viscothermal dissipation are compared and investigated....

  13. Isogeometric analysis of free-form Timoshenko curved beams including the nonlinear effects of large deformations

    Science.gov (United States)

    Hosseini, Seyed Farhad; Hashemian, Ali; Moetakef-Imani, Behnam; Hadidimoud, Saied

    2018-03-01

    In the present paper, the isogeometric analysis (IGA) of free-form planar curved beams is formulated based on the nonlinear Timoshenko beam theory to investigate the large deformation of beams with variable curvature. Based on the isoparametric concept, the shape functions of the field variables (displacement and rotation) in a finite element analysis are considered to be the same as the non-uniform rational basis spline (NURBS) basis functions defining the geometry. The validity of the presented formulation is tested in five case studies covering a wide range of engineering curved structures including from straight and constant curvature to variable curvature beams. The nonlinear deformation results obtained by the presented method are compared to well-established benchmark examples and also compared to the results of linear and nonlinear finite element analyses. As the nonlinear load-deflection behavior of Timoshenko beams is the main topic of this article, the results strongly show the applicability of the IGA method to the large deformation analysis of free-form curved beams. Finally, it is interesting to notice that, until very recently, the large deformations analysis of free-form Timoshenko curved beams has not been considered in IGA by researchers.

  14. 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.

  15. Angular scattering in electron capture and loss D- beam formation processes

    International Nuclear Information System (INIS)

    Coggiola, M.J.; Hodges, R.V.; Huestis, D.L.; Peterson, J.R.

    1980-01-01

    The development of high energy (> 150 keV) neutral beams for heating and fueling magnetic fusion devices depends on the ability to produce well-collimated negative ion beams. The double capture charge-exchange technique is a known, scalable method. In order to maximize the overall efficiency of the process and to achieve the desired beam characteristics, it is necessary to examine the optical qualities of the beams as well as the total efficiency of beam production. A combined modeling and experimental study of the angular scattering effects in negative ion formation and loss processes has therefore been undertaken

  16. Energy Deposition Simulations and Measurements in an LHC Collimator and Beam Loss Monitors

    CERN Document Server

    Böhlen, Till; Bracco, C; Dehning, B; Redaelli, S; Weiler, T; Zamantzas, C

    2010-01-01

    The LHC collimators are protected against beam-caused damages by measuring the secondary particle showers with beam loss monitors. Downstream of every collimator an ionisation chamber and a secondary emission monitor are installed to determine the energy deposition in the collimator. The relation between the energy deposition in the beam loss monitor and the collimator jaw is based on secondary shower simulations. To verify the FLUKA simulations, the prototype LHC collimator installed in the SPS was equipped with beam loss monitors. The results of the measurements of the direct impact of a 26 GeV proton beam injected in the SPS onto the collimator are compared with the predictions by FLUKA simulations. In addition, simulation results from parameter scans for mean and peak energy deposition with its dependencies are shown.

  17. Bending of I-beam with the transvers shear effect included – FEM calculated

    Energy Technology Data Exchange (ETDEWEB)

    Grygorowicz, Magdalena; Lewiński, Jerzy [Poznan University of Technology, Institute of Applied Mechanics ul. Jana Pawła II No. 24, 60-138 Poznań POLAND (Poland)

    2016-06-08

    The paper is devoted to three-point bending of an I-beam with include of transvers shear effect. Numerical calculations were conducted independently with the use of the SolidWorks system and the multi-purpose software package ANSYS The results of FEM study conducted with the use of two systems were compared and presented in tables and figures.

  18. Analog front end circuit design of CSNS beam loss monitor system

    International Nuclear Information System (INIS)

    Xiao Shuai; Guo Xian; Tian Jianmin; Zeng Lei; Xu Taoguang; Fu Shinian

    2013-01-01

    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. (authors)

  19. Renovation and Strengthening of Wooden Beams With CFRP Bands Including the Rheological Effects

    Directory of Open Access Journals (Sweden)

    Kula Krzysztof

    2016-09-01

    Full Text Available The paper presents a work analysis of wooden beams reinforced with glued composite bands from the top and resin inclusions, taking into account the rheology of materials. The paper presents numerical model of the multimaterial beam work including rheological phenomena described by linear equations of viscoelasticity. For the construction of this model one used MES SIMULIA ABAQUS environment in which were prepared its own procedures containing rheological models. The calculation results were compared with the literature data. One has done an analysis of the advisability of the use of CFRP reinforcements bands in terms of rheological phenomena.

  20. A Compactrio-Based Beam Loss Monitor For The SNS RF Test Cave

    International Nuclear Information System (INIS)

    Blokland, Willem; Armstrong, Gary A.

    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

  1. Electron beam guiding by grooved SiO{sub 2} parallel plates without energy loss

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Yingli; Yu, Deyang, E-mail: d.yu@impcas.ac.cn; Liu, Junliang; Zhang, Mingwu; Yang, Bian; Zhang, Yuezhao; Cai, Xiaohong [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2015-12-21

    Using a pair of grooved SiO{sub 2} parallel plates, stably guided electron beams were obtained without energy loss at 800–2000 eV. This shows that the transmitted electrons are guided by a self-organized repulsive electric field, paving the way for a self-adaptive manipulation of electron beams.

  2. Measuring Outcomes in Adult Weight Loss Studies That Include Diet and Physical Activity: A Systematic Review

    OpenAIRE

    Millstein, Rachel A.

    2014-01-01

    Background. Measuring success of obesity interventions is critical. Several methods measure weight loss outcomes but there is no consensus on best practices. This systematic review evaluates relevant outcomes (weight loss, BMI, % body fat, and fat mass) to determine which might be the best indicator(s) of success. Methods. Eligible articles described adult weight loss interventions that included diet and physical activity and a measure of weight or BMI change and body composition change. Resu...

  3. Linear coupling, loss and gain of counterpropagating beams

    Czech Academy of Sciences Publication Activity Database

    Peřinová, V.; Lukš, A.; Křepelka, Jaromír

    2006-01-01

    Roč. 39, č. 9 (2006), s. 2267-2284 ISSN 0953-4075 R&D Projects: GA MŠk(CZ) OC P11.003 Institutional research plan: CEZ:AV0Z10100522; CEZ:AV0Z10100520 Keywords : linear coupling * counterpropagating beams Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.024, year: 2006

  4. Simulations and Measurements of Secondary Electron Emission Beam Loss Monitors for LHC

    CERN Document Server

    Kramer, Daniel; Holzer, E B; Ferioli, G; Stockner, M

    2007-01-01

    Secondary Emission Monitor (SEM) is a part of the LHC Beam Loss Monitoring system, which is providing 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. SEM detectors will be used in the high dose rate environments of LHC because of their low sensitivity and excellent linearity. The design of SEM consists of two bias electrodes separating the produced secondary electrons from the Ti signal electrode placed in a vacuum steel cylinder. The response of the chamber was tested with bunched and continuous proton beams and compared with a reference detector and GEANT4 simulations.

  5. Energy loss of a high charge bunched electron beam in plasma: Simulations, scaling, and accelerating wakefields

    Directory of Open Access Journals (Sweden)

    J. B. Rosenzweig

    2004-06-01

    Full Text Available The energy loss and gain of a beam in the nonlinear, “blowout” regime of the plasma wakefield accelerator, which features ultrahigh accelerating fields, linear transverse focusing forces, and nonlinear plasma motion, has been asserted, through previous observations in simulations, to scale linearly with beam charge. Additionally, from a recent analysis by Barov et al., it has been concluded that for an infinitesimally short beam, the energy loss is indeed predicted to scale linearly with beam charge for arbitrarily large beam charge. This scaling is predicted to hold despite the onset of a relativistic, nonlinear response by the plasma, when the number of beam particles occupying a cubic plasma skin depth exceeds that of plasma electrons within the same volume. This paper is intended to explore the deviations from linear energy loss using 2D particle-in-cell simulations that arise in the case of experimentally relevant finite length beams. The peak accelerating field in the plasma wave excited behind the finite-length beam is also examined, with the artifact of wave spiking adding to the apparent persistence of linear scaling of the peak field amplitude into the nonlinear regime. At large enough normalized charge, the linear scaling of both decelerating and accelerating fields collapses, with serious consequences for plasma wave excitation efficiency. Using the results of parametric particle-in-cell studies, the implications of these results for observing severe deviations from linear scaling in present and planned experiments are discussed.

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

    International Nuclear Information System (INIS)

    Baumbaugh, A.; Briegel, C.; Brown, B.C.; Capista, D.; Drennan, C.; Fellenz, B.; Knickerbocker, K.; Lewis, J.D.; Marchionni, A.; Needles, C.; Olson, M.

    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 show a number of examples of its use in both the Main Injector and Tevatron.

  7. 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...

  8. Beam Loss Simulation and Collimator System Configurations for the Advanced Photon Source Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, A.; Borland, M.

    2017-06-25

    The proposed multi-bend achromat lattice for the Advanced Photon Source upgrade (APS-U) has a design emittance of less than 70 pm. The Touschek loss rate is high: compared with the current APS ring, which has an average beam lifetime ~ 10 h, the simulated beam lifetime for APS-U is only ~2 h when operated in the high flux mode (I=200 mA in 48 bunches). An additional consequence of the short lifetime is that injection must be more frequent, which provides another potential source of particle loss. In order to provide information for the radiation shielding system evaluation and to avoid particle loss in sensitive locations around the ring (for example, insertion device straight sections), simulations of the detailed beam loss distribution have been performed. Several possible collimation configurations have been simulated and compared.

  9. An approach to fundamental study of beam loss minimization

    International Nuclear Information System (INIS)

    Jameson, R.A.

    1999-01-01

    The accelerator design rules involving rms matching, developed at CERN in the 1970's, are discussed. An additional rule, for equipartitioning the beam energy among its degrees of freedom, may be added to insure an rms equilibrium conditions. If the strong stochasticity threshold is avoided, as it is in realistic accelerator designs, the dynamics is characterized by extremely long transient settling times, making the role of equipartitioning hard to explain. An approach to systematic study using the RFQ accelerator as a simulation testbed is discussed. New methods are available from recent advances in research on complexity, nonlinear dynamics, and chaos

  10. Magnetic field shielding by vacuum chambers of magnetic material for beam loss reduction

    International Nuclear Information System (INIS)

    Kamiya, Junichiro; Ogiwara, Norio; Hayashi, Naoki; Hotchi, Hideaki; Yoshimoto, Masahiro; Kinsho, Michikazu

    2012-01-01

    One of the reasons of a beam loss in a high power accelerator is leakage magnetic field from a magnet at a close beam line, which distorts the beam orbit and makes the beam hit the wall of the beam pipe. The most effective way to shield such leakage field is to cover the beam by the magnetic materials at the nearest space. This means that beam pipes and bellows be made of the magnetic materials. We plan to apply this method to the vacuum chambers of the beam extraction section of the J-PARC 3 GeV synchrotron, where the effect of the leakage magnetic field to the beam orbit is evident. However, there is few proven evidence of the vacuum chambers made of magnetic materials. Therefore we clarify the problems in producing beam pipes and bellows, which satisfy the magnetic and vacuum performance. In this article, we deliver the over view of the magnetic shielding project and our approaches to the problems in producing the vacuum chambers of magnetic materials. (author)

  11. Prestress Loss of CFL in a Prestressing Process for Strengthening RC Beams

    Directory of Open Access Journals (Sweden)

    Xinyan Guo

    2017-01-01

    Full Text Available A prestressing system was designed to strengthen reinforced concrete (RC beams with prestressed carbon fiber laminate (CFL. During different prestressing processes, prestress loss was measured using strain gauges attached on the surface of CFL along the length direction. The prestress loss was 50–68% of the whole prestress loss, which is typically associated with CFL slipping between the grip anchors. Approximately 20–27% of the prestress loss was caused by the elastic shortening of the RC beam. An analytical model using linear-elastic theory was constructed to calculate the prestress loss caused by CFL slipping between the anchors and the elastic shortening of the strengthened beams. The compared results showed that the analytical model of prestress loss can describe the experimental data well. Methods of reducing the prestress loss were also suggested. Compared to other experiments, the prestressing system proposed by this research group was effective because the maximum percentage of prestress loss was 14.9% and the average prestress loss was 12.5%.

  12. 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 (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 the lessons learned from this process are presented.

  13. Off-momentum loss maps with one beam

    CERN Document Server

    Garcia Morales, Hector; Salvachua Ferrando, Belen Maria; CERN. Geneva. ATS Department

    2016-01-01

    The aim of this MD is the benchmarking of simulation of off-momentum loss maps. This will help us to further understand the dynamics of the off-momentum collimation cleaning and give input to the determination of the operational settings of the off-momentum cleaning insertion. The MD was carried out during different end-of-fills of other MDs. In this note we summarize the procedures and the measurements taken during the MD week.

  14. Simulation study on beam loss in the alpha bucket regime during SIS-100 proton operation

    Science.gov (United States)

    Sorge, S.

    2018-02-01

    Crossing the transition energy γt in synchrotrons for high intensity proton beams requires well tuned jump schemes and is usually accompanied by longitudinal emittance growth. In order to avoid γt crossing during proton operation in the projected SIS-100 synchrotron special high-γt lattice settings have been developed, in order to keep γt above the beam extraction energy. A further advantage of this scheme is the formation of alpha buckets which naturally lead to short proton bunches, required for the foreseen production and storage of antiprotons for the FAIR facility. Special attention is turned on the imperfections of the superconducting SIS-100 magnets because together with the high-γt lattice settings, they could potentially lead to enhanced beam loss. The aim of the present work is to estimate the beam loss by means of particle tracking simulations.

  15. 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...

  16. BEAM DYNAMICS SIMULATIONS OF SARAF ACCELERATOR INCLUDING ERROR PROPAGATION AND IMPLICATIONS FOR THE EURISOL DRIVER

    CERN Document Server

    J. Rodnizki, D. Berkovits, K. Lavie, I. Mardor, A. Shor and Y. Yanay (Soreq NRC, Yavne), K. Dunkel, C. Piel (ACCEL, Bergisch Gladbach), A. Facco (INFN/LNL, Legnaro, Padova), V. Zviagintsev (TRIUMF, Vancouver)

    AbstractBeam dynamics simulations of SARAF (Soreq Applied Research Accelerator Facility) superconducting RF linear accelerator have been performed in order to establish the accelerator design. The multi-particle simulation includes 3D realistic electromagnetic field distributions, space charge forces and fabrication, misalignment and operation errors. A 4 mA proton or deuteron beam is accelerated up to 40 MeV with a moderated rms emittance growth and a high real-estate gradient of 2 MeV/m. An envelope of 40,000 macro-particles is kept under a radius of 1.1 cm, well below the beam pipe bore radius. The accelerator design of SARAF is proposed as an injector for the EURISOL driver accelerator. The Accel 176 MHZ β0=0.09 and β0=0.15 HWR lattice was extended to 90 MeV based on the LNL 352 MHZ β0=0.31 HWR. The matching between both lattices ensures smooth transition and the possibility to extend the accelerator to the required EURISOL ion energy.

  17. Comparison of measurements and modeling of beam ion loss during TAE avalanches in NSTX

    Science.gov (United States)

    Darrow, Douglass; Crocker, N.; Fredrickson, E.; Gorelenkov, N.; Podesta, M.; Shi, L.; White, R.

    2011-10-01

    Brief `avalanches' of toroidal Alfvén eigenmodes (TAEs) are observed in NSTX plasmas having several different n numbers simultaneously present. All are accompanied by a drop in the neutron rate, indicating likely loss of beam ions. However, the scintillator fast ion loss detector at the wall on NSTX registers losses only for some avalanches and not others. When losses are seen, they cover a wide range of pitch angles, suggesting that the modes cause stochasticity in the beam ion phase space. A 16 channel array of microwave reflectometers provides a radial profile of the structure of each n TAE, which can then be used to produce an absolute amplitude for a TAE mode structure computed by the NOVA code for the plasma at the time of interest. Using the equilibrium plus the TAE modes structures in the guiding center code ORBIT then allows modeling of the effect of the avalanches on beam ion orbits. The modeling does reveal stochastic behavior and loss of some classes of orbits that are populated by the neutral beams on NSTX, with an amplitude threshold for loss that is close to that observed in the experiments. This work supported by US DoE contract DE-ACO2-09CH11466 and the China Scholarship Council.

  18. 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...

  19. 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.

  20. Design for low beam loss in accelerators for intense neutron source applications

    International Nuclear Information System (INIS)

    Jameson, R.A.

    1993-01-01

    Control of beam loss in intense ion linacs involves keeping beam spill below parts in 10 -5 --10 -8 /m by preventing total beam size from extending to the limiting apertures. Starting from good rms design practices, new analysis of the machine architecture is described in terms of the effects of the machine tune with space-charge, free-energy constraint, and halo-producing mechanisms. It is shown that halos are produced by the time- (or position-) varying nature of common linac aspects (such as misalignment, mismatching, acceleration, and construction techniques) through collective core/single-particle interaction dynamics plus resonances

  1. Comparison of measured and computed loss to parasitic modes in cylindrical cavities with beam ports

    International Nuclear Information System (INIS)

    Wilson, P.B.; Styles, J.B.; Bane, K.L.F.

    1977-03-01

    Good agreement was obtained between computed values and results from a bench measurement technique for the total loss to parasitic modes in several cylindrical cavities with beam ports. The measurement of loss as a function of time within the current pulse also gives results which are in good agreement with computed functions, especially considering the fact that there are questionable points concerning both the theory and the measurement technique. Within measurement errors, there is also agreement in a few cases where a comparison is possible between a bench measurement result and the heating produced directly in a component by the SPEAR beam

  2. Analysis of sub-bandgap losses in TiO2 coating deposited via single and dual ion beam deposition

    Czech Academy of Sciences Publication Activity Database

    Žídek, Karel; Hlubuček, Jiří; Horodyská, Petra; Budasz, Jiří; Václavík, Jan

    2017-01-01

    Roč. 626, March (2017), s. 60-65 ISSN 0040-6090 R&D Projects: GA MŠk(CZ) LO1206 Institutional support: RVO:61389021 Keywords : Ion beam deposition * Titanium dioxide * Optical coating * Sub-bandgap losses * Urbach tail Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 1.879, year: 2016 http://www.sciencedirect.com/science/article/pii/S0040609017301256

  3. Beam loss reduction by injection painting in the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

    Directory of Open Access Journals (Sweden)

    H. Hotchi

    2012-04-01

    Full Text Available The 3-GeV rapid cycling synchrotron (RCS of the Japan Proton Accelerator Research Complex was commissioned in October 2007. Via the initial beam tuning and a series of underlying beam studies with low-intensity beams, since December 2009, we have intermittently been performing beam tuning experiments with higher-intensity beams including the injection painting technique. By optimizing the injection painting parameters, we have successfully achieved a 420 kW-equivalent output intensity at a low-level intensity loss of less than 1%. Also the corresponding numerical simulation well reproduced the observed painting parameter dependence on the beam loss, and captured a characteristic behavior of the high-intensity beam in the injection painting process. In this paper, we present the experimental results obtained in the course of the RCS beam power ramp-up, especially on the beam loss reduction achieved by employing the injection painting, together with the numerical simulation results.

  4. Cavity loss factors of non-relativistic beams for Project X

    Energy Technology Data Exchange (ETDEWEB)

    Lunin, A.; Yakovlev, V.; Kazakov, S.; /Fermilab

    2011-03-01

    Cavity loss factor calculation is an important part of the total cryolosses estimation for the super conductive (SC) accelerating structures. There are two approaches how to calculate cavity loss factors, the integration of a wake potential over the bunch profile and the addition of loss factors for individual cavity modes. We applied both methods in order to get reliable results for non-relativistic beam. The time domain CST solver was used for a wake potential calculation and the frequency domain HFSS code was used for the cavity eigenmodes spectrum findings. Finally we present the results of cavity loss factors simulations for a non-relativistic part of the ProjectX and analyze it for various beam parameters.

  5. 75 FR 26793 - Beam Global Spirits & Wine, Including On-Site Leased Workers from Adecco, St. Elizabeth Business...

    Science.gov (United States)

    2010-05-12

    ... DEPARTMENT OF LABOR Employment and Training Administration [TA-W-73,194] Beam Global Spirits & Wine, Including On-Site Leased Workers from Adecco, St. Elizabeth Business Health, Guardsmark, and Lab... 26, 2010, applicable to workers of Beam Global Spirits & Wine, including on-site leased workers from...

  6. Implementation aspects of the Boundary Element Method including viscous and thermal losses

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Juhl, Peter Møller

    2014-01-01

    The implementation of viscous and thermal losses using the Boundary Element Method (BEM) is based on the Kirchhoff’s dispersion relation and has been tested in previous work using analytical test cases and comparison with measurements. Numerical methods that can simulate sound fields in fluids in...... with mesh definition, geometrical singularities and treatment of closed cavities. These issues are specific of the BEM with losses. Using examples, some strategies are presented that can alleviate shortcomings and improve performance....... including losses are particularly interesting whenever small cavities and narrow passages are present, as is the case with many acoustic devices such as transducers and small audio appliances. The present paper describes current work aimed at improving the method by addressing some specific issues related...

  7. 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...

  8. 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 ...

  9. Heavy ion beam loss mechanisms at an electron-ion collider

    Directory of Open Access Journals (Sweden)

    Spencer R. Klein

    2014-12-01

    Full Text Available There are currently several proposals to build a high-luminosity electron-ion collider, to study the spin structure of matter and measure parton densities in heavy nuclei, and to search for gluon saturation and new phenomena like the colored glass condensate. These measurements require operation with heavy nuclei. We calculate the cross sections for two important processes that will affect accelerator and detector operations: bound-free pair production and Coulomb excitation of the nuclei. Both of these reactions have large cross sections, 28–56 mb, which can lead to beam ion losses, produce beams of particles with altered charge:mass ratio, and produce a large flux of neutrons in zero degree calorimeters. The loss of beam particles limits the sustainable electron-ion luminosity to levels of several times 10^{32}/cm^{2}/s.

  10. 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...

  11. 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.

  12. Dynamic Analysis of Thick Plates Including Deep Beams on Elastic Foundations Using Modified Vlasov Model

    Directory of Open Access Journals (Sweden)

    Korhan Ozgan

    2013-01-01

    Full Text Available Dynamic analysis of foundation plate-beam systems with transverse shear deformation is presented using modified Vlasov foundation model. Finite element formulation of the problem is derived by using an 8-node (PBQ8 finite element based on Mindlin plate theory for the plate and a 2-node Hughes element based on Timoshenko beam theory for the beam. Selective reduced integration technique is used to avoid shear locking problem for the evaluation of the stiffness matrices for both the elements. The effect of beam thickness, the aspect ratio of the plate and subsoil depth on the response of plate-beam-soil system is analyzed. Numerical examples show that the displacement, bending moments and shear forces are changed significantly by adding the beams.

  13. Residual activity induced by heavy ions and beam-loss criteria for heavy-ion accelerators

    Directory of Open Access Journals (Sweden)

    I. Strašík

    2010-07-01

    Full Text Available The paper presents results of FLUKA simulations of the residual activity induced by heavy ions in two target configurations representing: (1 a beam pipe of an accelerator and (2 a bulky accelerator structure like a magnet yoke or a coil. The target materials were stainless steel and copper representing the most common construction materials used for basic accelerator components. For these two materials, the inventory of the induced isotopes depends mainly on the target material and much less on the projectile species. Time evolution of the induced activity can be described by means of a generic curve that is independent from the projectile mass. Dependence of the induced residual activity on selected ion beam parameters was studied. The main goal of the study was establishing a scaling law expanding the existing proton beam-loss tolerance to heavy-ion beams. This scaling law enables specifying beam-loss criteria for projectile species from proton up to uranium at energies from 200  MeV/u up to 1  GeV/u.

  14. 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 ...

  15. 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.

  16. 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 ...

  17. Duration of memory loss due to electron beam exposure. Final report Jan-May 1983

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, T.G.; Tilton, B.M.

    1983-08-01

    Electron beam exposure has been shown to produce retrograde amnesia (RA). The objective of this study was to determine the duration of memory loss upon electron beam exposure. It is important to know if exposure produces a memory loss of the events which occurred in the preceding 1 sec or memory loss of the preceding minute's events. The task was a single-trial avoidance paradigm. The animal was placed in a small aversive chamber. After a 90-sec adaptation period, a door opened that provided access to a large, dark, preferred chamber. The time required for the animal to enter the preferred chamber was the measure of interest (T). Once inside the preferred chamber, a 1-sec footshock was delivered. Following the footshock by some preset delay (delta T), the animal was exposed to a 10-microsec, 10-rad electron beam (or X-ray). A second trial on the task was run 2 hr postexposure. The second trial consisted of placing the animal in the aversive chamber and monitoring the time (T') required to enter the preferred chamber. If the electron beam exposure interfered with the animal's ability to recall the shock, T' would be greatly reduced as compared with the sham controls. The exposure delay times used were delta T = 1, 3, 5, and 10 sec.

  18. Long duration blade loss simulations including thermal growths for dual-rotor gas turbine engine

    Science.gov (United States)

    Sun, Guangyoung; Palazzolo, Alan; Provenza, A.; Lawrence, C.; Carney, K.

    2008-09-01

    This paper presents an approach for blade loss simulation including thermal growth effects for a dual-rotor gas turbine engine supported on bearing and squeeze film damper. A nonlinear ball bearing model using the Hertzian formula predicts ball contact load and stress, while a simple thermal model estimates the thermal growths of bearing components during the blade loss event. The modal truncation augmentation method combined with a proposed staggered integration scheme is verified through simulation results as an efficient tool for analyzing a flexible dual-rotor gas turbine engine dynamics with the localized nonlinearities of the bearing and damper, with the thermal growths and with a flexible casing model. The new integration scheme with enhanced modeling capability reduces the computation time by a factor of 12, while providing a variety of solutions with acceptable accuracy for durations extending over several thermal time constants.

  19. Low-beam-loss design of a compact, high-current deuteron radio frequency quadrupole accelerator

    Directory of Open Access Journals (Sweden)

    C. Zhang

    2004-10-01

    Full Text Available A 201.5 MHz, 50 mA, 2.0 MeV deuteron radio frequency quadrupole accelerator is proposed as the neutron generator for the neutron experiment facility project at Peking University, China. Based on better understanding of beam losses, some new optimization procedures concerning both longitudinal and transverse dynamics are adopted. Accordingly, the beam transmission efficiency is improved from 91.2% to 98.3% and the electrode length is shortened from 2.91 to 2.71 m. The fundamental physical analyses are performed to look inside the new design recipe and explain why it works.

  20. Allotropic effects on the energy loss of swift H+ and He+ ion beams through thin foils

    International Nuclear Information System (INIS)

    Garcia-Molina, Rafael; Abril, Isabel; Denton, Cristian D.; Heredia-Avalos, Santiago

    2006-01-01

    We have developed a theoretical treatment and a simulation code to study the energy loss of swift H + and He + ion beams interacting with thin foils of different carbon allotropes. The former is based on the dielectric formalism, and the latter combines Monte Carlo with the numerical solution of the motion equation for each projectile to describe its trajectory and interactions through the target. The capabilities of both methods are assessed by the reasonably good agreement between their predictions and the experimental results, for a wide range of projectile energies and target characteristics. Firstly, we apply the theoretical procedure to calculate the stopping cross sections for H + and He + beams in foils of different allotropic forms of carbon (such as diamond, graphite, amorphous carbon, glassy carbon and C 60 -fullerite), as a function of the projectile energy. We take into account the electronic structure of the projectile, as well as the different charge states it can acquire, the energy loss associated to the electronic capture and loss processes, the polarization of the projectile, and a realistic description of the target. On the other hand, the simulation code is used to evaluate the energy distributions of swift H + and He + ion beams when traversing several foils of the above mentioned allotropic forms of carbon, in order to analyze the influence of the chemical and physical state of the target in the projectile energy loss. These allotropic effects are found to become more important around the maximum of the stopping cross-section

  1. New data acquisition system for beam loss monitor used in J-PARC main ring

    Science.gov (United States)

    Satou, K.; Toyama, T.; Kamikubota, N.; Yoshida, S.; Matsushita, J.; Wakita, T.; Sugiyama, M.; Morino, T.

    2018-04-01

    A new data acquisition system has been developed continually as a part of the development of a new beam loss monitor (BLM) system for the J-PARC main ring. This development includes a newly designed front-end isolation amp that uses photo-couplers and a VME-based new analog-to-digital converter (ADC) system. Compared to the old amp, the new amp has a 10 times higher conversion impedance for the input current to the output voltage; this value is 1 M Ω. Moreover, the bandwidth was improved to from DC to 50 kHz, which is about two orders of magnitude greater than the previously used bandwidth. The theoretical estimations made in this study roughly agree with the frequency response obtained for the new system. The new ADC system uses an on-board field-programmable gate array chip for signal processing. By replacing the firmware of this chip, changes pertaining to future accelerator upgrade plans may be introduced into the new ADC system; in addition, the ADC system can be used in other applications. The sampling speed of the system is 1 MS/s, and it exhibits a 95 dBc spurious-free dynamic range and 16.5 effective number of bits. The obtained waveform and integrated charge data are compared with two reference levels in the ADC system. If the data exceeds the reference level, the system generates an alarm to dump the beams. By using the new data acquisition system, it was proved that the new BLM system shows a wide dynamic range of 160 dB. In this study, the details of the new data acquisition system are described.

  2. Propagation and Loss-Cone Properties of Relativistic Electron Beams in the Magnetosphere

    Science.gov (United States)

    Sanchez, E. R.; Powis, A.; Greklek, M.; Porazik, P.; Kaganovich, I.

    2017-12-01

    One of the main obstacles for achieving closure of several key outstanding questions in magnetospheric physics has been the lack of accurate magnetic field mapping between processes or regions in the magnetosphere and their ionospheric foot-points. Accurate correspondence between magnetospheric processes or regions and their ionospheric foot-points can be achieved with beams of MeV electrons that propagate along magnetic-field lines in fractions of a second, emitted by compact linear accelerators under controlled conditions at specified points in the magnetosphere, while the atmospheric imprint created by their precipitation is detected by an array of ground-based optical imagers, radars, riometers or X-ray detectors. To prove that successful magnetic field mapping is possible, we must ensure that the beam can be injected into the loss cone, that the spacecraft potentials induced by the beam emission are manageable, that the beam propagates all the way into the topside ionosphere, and that the beam produces a signature detectable from the ground or from low altitude. In this work, we present the latest results of calculations of beam injection and propagation for a wide range of injection distances in the magnetotail equator and geomagnetic conditions to determine under what conditions beams emitted from the magnetosphere would be able to propagate to the topside ionosphere with enough intensity to be detected by ground-based or low-altitude instrumentation. Using ballistic simulations of charged particle motion, we demonstrate that relativistic electron beams can be successfully injected into the loss cone under both ideal (analytic dipole) and realistic (MHD modeled) magnetosphere conditions from a wide range of injection positions. For identical injection coordinates, the impact location on the top of the atmosphere is dependent on the current magnetosphere conditions, demonstrating that this technique can distinguish between the phases of a geomagnetic storm

  3. Measuring Outcomes in Adult Weight Loss Studies That Include Diet and Physical Activity: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Rachel A. Millstein

    2014-01-01

    Full Text Available Background. Measuring success of obesity interventions is critical. Several methods measure weight loss outcomes but there is no consensus on best practices. This systematic review evaluates relevant outcomes (weight loss, BMI, % body fat, and fat mass to determine which might be the best indicator(s of success. Methods. Eligible articles described adult weight loss interventions that included diet and physical activity and a measure of weight or BMI change and body composition change. Results. 28 full-text articles met inclusion criteria. Subjects, settings, intervention lengths, and intensities varied. All studies measured body weight (−2.9 to −17.3 kg, 9 studies measured BMI (−1.1 to −5.1 kg/m2, 20 studies measured % body fat (−0.7 to −10.2%, and 22 studies measured fat mass (−0.9 to −14.9 kg. All studies found agreement between weight or BMI and body fat mass or body fat % decreases, though there were discrepancies in degree of significance between measures. Conclusions. Nearly all weight or BMI and body composition measures agreed. Since body fat is the most metabolically harmful tissue type, it may be a more meaningful measure of health change. Future studies should consider primarily measuring % body fat, rather than or in addition to weight or BMI.

  4. 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.

  5. Measurements of the relative sensitivities between some beam-loss monitors, PART II

    CERN Document Server

    Bosser, Jacques; CERN. Geneva. SPS and LEP Division

    1998-01-01

    We measured the relative sensitivity of various types of classical beam-loss monitors following on from and in the spirit of a previous work. The detectors were tested in one of the SPS extraction l ines. The particles passing through the line consist of 2/3 protons and 1/3 pions at 120 Gev/c. The low extracted (spill time 2.5 s) beam intensity can be adjusted. Upstream of the detectors a copp er target (diameter: 7 cm, length: 50 cm) can be placed on the beam axis. First we proceed with linearity and sensitivity measurements of various types of detectors used in counting or analog mode. Next, with a view to increasing the dynamic range we pursue out tests with a dedicated type of electronics. Finally, measurements have been made in order to determine, in the frame of our experiment , the minimum detection level of some monitors.

  6. FESA class for off-momentum lossmaps and decomposition of beam losses at LHC

    CERN Document Server

    Wyszynski, Michal Jakub; Pojer, Mirko; Salvachua Ferrando, Belen Maria; Valentino, Gianluca; CERN. Geneva. ATS Department

    2016-01-01

    The project consisted of two main parts. The first part was to build a FESA class which would serve as lossmap feedback controller for off-momentum lossmaps, capable of handling 100 Hz BLM data, contrary to existing controller. Thanks to the efficient management RF frequency, beam dumps during this procedure would be avoided and machine availability would improve by shortening the duration of machine validation after technical stops. The second part concerned identification of beam losses at the LHC. It was a continuation of author’s work done as Summer Student project. The aim was to identify issues with the existing losses decomposition matrix for flat top, apply necessary corrections and construct analogous matrix for injection.

  7. Accidental beam loss in superconducting accelerators: Simulations, consequences of accidents and protective measures

    International Nuclear Information System (INIS)

    Drozhdin, A.; Mokhov, N.; Parker, B.

    1994-02-01

    The consequences of an accidental beam loss in superconducting accelerators and colliders of the next generation range from the mundane to rather dramatic, i.e., from superconducting magnet quench, to overheating of critical components, to a total destruction of some units via explosion. Specific measures are required to minimize and eliminate such events as much as practical. In this paper we study such accidents taking the Superconducting Supercollider complex as an example. Particle tracking, beam loss and energy deposition calculations were done using the realistic machine simulation with the Monte-Carlo codes MARS 12 and STRUCT. Protective measures for minimizing the damaging effects of prefire and misfire of injection and extraction kicker magnets are proposed here

  8. Interaction between corrosion crack width and steel loss in RC beams corroded under load

    International Nuclear Information System (INIS)

    Malumbela, Goitseone; Alexander, Mark; Moyo, Pilate

    2010-01-01

    This paper presents results and discussions on an experimental study conducted to relate the rate of widening of corrosion cracks with the pattern of corrosion cracks as well as the level of steel corrosion for RC beams (153 x 254 x 3000 mm) that were corroded whilst subjected to varying levels of sustained loads. Steel corrosion was limited to the tensile reinforcement and to a length of 700 mm at the centre of the beams. The rate of widening of corrosion cracks as well as strains on uncracked faces of RC beams was constantly monitored during the corrosion process, along the corrosion region and along other potential cracking faces of beams using a demec gauge. The distribution of the gravimetric mass loss of steel along the corrosion region was measured at the end of the corrosion process. The results obtained showed that: the rate of widening of each corrosion crack is dependent on the overall pattern of the cracks whilst the rate of corrosion is independent of the pattern of corrosion cracks. A mass loss of steel of 1% was found to induce a corrosion crack width of about 0.04 mm.

  9. Precessed electron beam electron energy loss spectroscopy of graphene: Beyond channelling effects

    International Nuclear Information System (INIS)

    Yedra, Ll.; Estradé, S.; Torruella, P.; Eljarrat, A.; Peiró, F.; Darbal, A. D.; Weiss, J. K.

    2014-01-01

    The effects of beam precession on the Electron Energy Loss Spectroscopy (EELS) signal of the carbon K edge in a 2 monolayer graphene sheet are studied. In a previous work, we demonstrated the use of precession to compensate for the channeling-induced reduction of EELS signal when in zone axis. In the case of graphene, no enhancement of EELS signal is found in the usual experimental conditions, as graphene is not thick enough to present channeling effects. Interestingly, though it is found that precession makes it possible to increase the collection angle, and, thus, the overall signal, without a loss of signal-to-background ratio

  10. Instrumentation for EXELFS measurements using convergent beam diffraction coupling to the electron energy loss spectrometer

    International Nuclear Information System (INIS)

    Yuan Zou Wei; Csillag, S.; Tafreshi, M.A.

    1993-08-01

    Convergent beam diffraction coupling between a JEOL-100C scanning transmission microscope and an electron energy loss spectrometer is realised for the purpose of Extended Energy Loss Fine Structure (EXELFS) measurements. The working principle, the instrumentation for this coupling mode and some specific details, such as condenser system, shadow image, focusing conditions and measurement of convergent angles are described and discussed. The combination of a quadrupole and cylindrical lens for magnifying the image and increasing the dispersion of spectrum, together with a new type of compensation circuit for stray magnetic fields and the arrangement of the parallel recording system are also reported

  11. 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...

  12. 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...

  13. 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.

  14. Development of the Readout Electronics for the Beam Loss Monitors of the LHC

    CERN Document Server

    Friesenbichler, W

    2002-01-01

    The Large Hadron Collider (LHC) of the European Laboratory for Particle Physics will be the largest particle accelerator in the world. It requires a large number of installations for its operation. One of these installations are the beam loss monitors which measure the particle losses. If these losses exceed a certain level, the beam must be extracted, otherwise the superconducting magnets could be damaged. For this reason, ionization chambers are installed outside the cryostat to transform the losses into an electric current. A wide dynamic range front end was developed to measure this current. The circuit consists of a current-to-frequency converter that works on the principle of balanced charge. Its output frequency is evaluated by counters and the data is serially transmitted from the tunnel to the surface, where the final data processing is performed. The data transmission suffers from the long cabling distance of up to 2 km. Using Manchester Code and line equalizers enables a data rate of 2 Mbit/s over ...

  15. Reliability of the beam loss monitors system for the large hadron collider at CERN

    International Nuclear Information System (INIS)

    Guaglio, G.

    2005-12-01

    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. 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)

  16. Dynamic behavior of a rotating delaminated composite beam including rotary inertia and shear deformation effects

    Directory of Open Access Journals (Sweden)

    Ramazan-Ali Jafari-Talookolaei

    2015-09-01

    Full Text Available A finite element (FE model is developed to study the free vibration of a rotating laminated composite beam with a single delamination. The rotary inertia and shear deformation effects, as well as the bending–extension, bending–twist and extension–twist coupling terms are taken into account in the FE model. Comparison between the numerical results of the present model and the results published in the literature verifies the validity of the present model. Furthermore, the effects of various parameters, such as delamination size and location, fiber orientation, hub radius, material anisotropy and rotating speed, on the vibration of the beam are studied in detail. These results provide useful information in the study of the free vibration of rotating delaminated composite beams.

  17. The potential of proton beam radiation therapy in lung cancer (including mesothelioma)

    Energy Technology Data Exchange (ETDEWEB)

    Bjelkengren, Goeran [Univ. Hospital, Malmoe (Sweden). Dept. of Oncology; Glimelius, Bengt [Karolinska Inst., Stockholm (Sweden). Dept. of Oncology and Pathology; Akademiska sjukhuset, Uppsala (Sweden). Dept. of Oncology, Radiology and Clinical Immunology

    2005-12-01

    A Swedish group of oncologists and hospital physicists have estimated the number of patients in Sweden suitable for proton beam therapy. The estimations have been based on current statistics of tumour incidence, number of patients potentially eligible for radiation treatment, scientific support from clinical trials and model dose planning studies and knowledge of the dose-response relations of different tumours and normal tissues. It is estimated that about 350 patients with lung cancer and about 20 patients with mesothelioma annually may benefit from proton beam therapy.

  18. Analytical linear energy transfer model including secondary particles: calculations along the central axis of the proton pencil beam

    International Nuclear Information System (INIS)

    Marsolat, F; De Marzi, L; Mazal, A; Pouzoulet, F

    2016-01-01

    In proton therapy, the relative biological effectiveness (RBE) depends on various types of parameters such as linear energy transfer (LET). An analytical model for LET calculation exists (Wilkens’ model), but secondary particles are not included in this model. In the present study, we propose a correction factor, L sec , for Wilkens’ model in order to take into account the LET contributions of certain secondary particles. This study includes secondary protons and deuterons, since the effects of these two types of particles can be described by the same RBE-LET relationship. L sec was evaluated by Monte Carlo (MC) simulations using the GATE/GEANT4 platform and was defined by the ratio of the LET d distributions of all protons and deuterons and only primary protons. This method was applied to the innovative Pencil Beam Scanning (PBS) delivery systems and L sec was evaluated along the beam axis. This correction factor indicates the high contribution of secondary particles in the entrance region, with L sec values higher than 1.6 for a 220 MeV clinical pencil beam. MC simulations showed the impact of pencil beam parameters, such as mean initial energy, spot size, and depth in water, on L sec . The variation of L sec with these different parameters was integrated in a polynomial function of the L sec factor in order to obtain a model universally applicable to all PBS delivery systems. The validity of this correction factor applied to Wilkens’ model was verified along the beam axis of various pencil beams in comparison with MC simulations. A good agreement was obtained between the corrected analytical model and the MC calculations, with mean-LET deviations along the beam axis less than 0.05 keV μm −1 . These results demonstrate the efficacy of our new correction of the existing LET model in order to take into account secondary protons and deuterons along the pencil beam axis. (paper)

  19. Size-dependent nonlinear bending of micro/nano-beams made of nanoporous biomaterials including a refined truncated cube cell

    Science.gov (United States)

    Sahmani, S.; Aghdam, M. M.

    2017-12-01

    Morphology and pore size plays an essential role in the mechanical properties as well as the associated biological capability of a porous structure made of biomaterials. The objective of the current study is to predict the Young's modulus and Poisson's ratio of nanoporous biomaterials including refined truncated cube cells based on a hyperbolic shear deformable beam model. Analytical relationships for the mechanical properties of nanoporous biomaterials are given as a function of the refined cell's dimensions. After that, the size dependency in the nonlinear bending behavior of micro/nano-beams made of such nanoporous biomaterials is analyzed using the nonlocal strain gradient elasticity theory. It is assumed that the micro/nano-beam has one movable end under axial compression in conjunction with a uniform distributed lateral load. The Galerkin method together with an improved perturbation technique is employed to propose explicit analytical expression for nonlocal strain gradient load-deflection curves of the micro/nano-beams made of nanoporous biomaterials subjected to uniform transverse distributed load. It is found that through increment of the pore size, the micro/nano-beam will undergo much more deflection corresponding to a specific distributed load due to the reduction in the stiffness of nanoporous biomaterial. This pattern is more prominent for lower value of applied axial compressive load at the free end of micro/nano-beam.

  20. Loss and thermal model for power semiconductors including device rating information

    DEFF Research Database (Denmark)

    Ma, Ke; Bahman, Amir Sajjad; Beczkowski, Szymon

    2014-01-01

    pre-defined by experience with poor design flexibility. Consequently a more complete loss and thermal model is proposed in this paper, which takes into account not only the electrical loading but also the device rating as input variables. The quantified correlation between the power loss, thermal...

  1. Evaluation of support loss in micro-beam resonators: A revisit

    Science.gov (United States)

    Chen, S. Y.; Liu, J. Z.; Guo, F. L.

    2017-12-01

    This paper presents an analytical study on evaluation of support loss in micromechanical resonators undergoing in-plane flexural vibrations. Two-dimensional elastic wave theory is used to determine the energy transmission from the vibrating resonator to the support. Fourier transform and Green's function technique are adopted to solve the problem of wave motions on the surface of the support excited by the forces transmitted by the resonator onto the support. Analytical expressions of support loss in terms of quality factor, taking into account distributed normal stress and shear stress in the attachment region, and coupling between the normal stress and shear stress as well as material disparity between the support and the resonator, have been derived. Effects of geometry of micro-beam resonators, and material dissimilarity between support and resonator on support loss are examined. Numerical results show that 'harder resonator' and 'softer support' combination leads to larger support loss. In addition, the Perfectly Matched Layer (PML) numerical simulation technique is employed for validation of the proposed analytical model. Comparing with results of quality factor obtained by PML technique, we find that the present model agrees well with the results of PML technique and the pure-shear model overestimates support loss noticeably, especially for resonators with small aspect ratio and large material dissimilarity between the support and resonator.

  2. Comparison of LHC Beam Loss Maps Using the Transverse Damper Blow Up and Tune Resonance Crossing Methods

    CERN Document Server

    Moens, V; Redaelli, S; Salvachua, B; Valentino, G

    2013-01-01

    The LHC collimator settings are qualified regularly via beam loss maps. In this procedure, the beam is artificially excited to create abnormal loss rates. The transverse damper blow up (ADT) and tune resonance crossing methods (QT) are used to increase the betatron amplitude of particles and verify the efficiency of the collimation cleaning hierarchy in IR7. This paper presents a quantitative comparison of the methods, for the qualification of the collimator settings at different operating points in the LHC machine cycle. The analysis is done using Beam Loss Monitor (BLM) with integration times of 1.3 s and 80 ms, the latter being available as from the 2012 run onwards. We present here the use of the faster BLM data (80 ms) to study the time evolution of the losses in IR3 and IR7 during offmomentum loss maps.

  3. Beam loss problems and acceleration of proton currents of 300 mA in the Fermilab 200-MeV linear accelerator

    International Nuclear Information System (INIS)

    Young, D.E.

    1977-01-01

    Two types of proton beam-loss problems that must be managed are discussed. A fast loss of the beam happens usually when a sudden malfunction of a component or system occurs. Slow loss of beam occurs when components deviate slightly from their ideal values, when misalignments occur, when high-intensity effects cause a growth in beam size, when extraneous resonance effects occur, or in any of a large number of other ways. The loss of beam is gradual and if the loss of beam is allowed to continue large levels of residual radioactivity can build up. Beam losses in the 500-GeV Main Ring Synchrotron and in the Fermilab 200-MeV Linear Accelerator are discussed, and the experience acquired for the latter is generalized for other linear accelerators. Production of 300 mA proton beams in the Fermilab Linac is described

  4. Prompt Loss of Energetic Ions during Early Neutral Beam Injection in the National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    S.S. Medley; D.S. Darrow; D. Liu; A.L. Roquemore

    2005-03-25

    Early neutral-beam injection is used in the National Spherical Torus Experiment (NSTX) to heat the electrons and slow current penetration which keeps q(0) elevated to avoid deleterious MHD activity and at the same time reduces Ohmic flux consumption, all of which aids long-pulse operation. However, the low plasma current (I{sub p} {approx} 0.5 MA) and electron density (n{sub e} {approx} 1 x 10{sup 13} cm{sup -3}) attending early injection lead to elevated orbit and shine through losses. The inherent orbit losses are aggravated by large excursions in the outer gap width during current ramp-up. An investigation of this behavior using various energetic particle diagnostics on NSTX and TRANSP code analysis is presented.

  5. Experimental investigation of the ripple induced losses of perpendicularly injected beam ions in the low aspect ratio helical system CHS

    International Nuclear Information System (INIS)

    Isobe, M.; Sasao, M.; Okamura, S.; Murakami, S.; Minami, T.; Kado, S.; Ida, K.; Osakabe, M.; Yoshimura, Y.; Tanaka, K.; Takahashi, C.; Nishimura, S.; Matsuoka, K.; Kondo, T.; Shimizu, A.; Yavorskij, V.A.

    2001-01-01

    Confinement of perpendicularly injected beam ions has been investigated experimentally both in the standard configuration and in the drift optimized configuration of the CHS heliotron/torsatron by means of the neutron technique. The experimental results indicate that the confinement of trapped beam ions is poor in both configurations. The observed loss rate of trapped beam ions was very high and this high rate is not explained by losses due to charge exchange or collisional scattering from the timescale perspective. Full gyro-motion following orbit calculations showed that in the peripheral region of CHS plasmas, trapped beam ions are promptly lost because they immediately intersect the vacuum chamber wall due to their large Larmor radii. It also suggested that in the core domain the collisionless transition behaviour is the key to understanding the rapid loss of beam ions. It was shown that the magnetic moment of perpendicularly injected beam ions is not well conserved in CHS. The rapid losses of perpendicularly injected beam ions are probably due to non-adiabatic effects resulting in the transition behaviour of energetic ions. (author)

  6. Experimental investigation of the ripple induced losses of perpendicularly injected beam ions in the low aspect ratio helical system CHS

    Science.gov (United States)

    Isobe, M.; Sasao, M.; Okamura, S.; Kondo, T.; Murakami, S.; Minami, T.; Kado, S.; Ida, K.; Shimizu, A.; Osakabe, M.; Yoshimura, Y.; Tanaka, K.; Takahashi, C.; Nishimura, S.; Matsuoka, K.; CHS Group; Yavorskij, V. A.

    2001-09-01

    Confinement of perpendicularly injected beam ions has been investigated experimentally both in the standard configuration and in the drift optimized configuration of the CHS heliotron/torsatron by means of the neutron technique. The experimental results indicate that the confinement of trapped beam ions is poor in both configurations. The observed loss rate of trapped beam ions was very high and this high rate is not explained by losses due to charge exchange or collisional scattering from the timescale perspective. Full gyro-motion following orbit calculations showed that in the peripheral region of CHS plasmas, trapped beam ions are promptly lost because they immediately intersect the vacuum chamber wall due to their large Larmor radii. It also suggested that in the core domain the collisionless transition behaviour is the key to understanding the rapid loss of beam ions. It was shown that the magnetic moment of perpendicularly injected beam ions is not well conserved in CHS. The rapid losses of perpendicularly injected beam ions are probably due to non-adiabatic effects resulting in the transition behaviour of energetic ions.

  7. IMPACT simulation and the SNS linac beam

    International Nuclear Information System (INIS)

    Zhang, Y.; Qiang, J.

    2008-01-01

    Multi-particle tracking simulations for the SNS linac beam dynamics studies are performed with the IMPACT code. Beam measurement results are compared with the computer simulations, including beam longitudinal halo and beam losses in the superconducting linac, transverse beam Courant-Snyder parameters and the longitudinal beam emittance in the linac. In most cases, the simulations show good agreement with the measured results

  8. An axisymmetric boundary element formulation of sound wave propagation in fluids including viscous and thermal losses

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Juhl, Peter Møller

    2013-01-01

    The formulation presented in this paper is based on the Boundary Element Method (BEM) and implements Kirchhoff’s decomposition into viscous, thermal and acoustic components, which can be treated independently everywhere in the domain except on the boundaries. The acoustic variables with losses ar...... as is the case with the existing Finite Element Method (FEM) implementations with losses. The suitability of this approach is demonstrated using an axisymmetrical BEM and two test cases where the numerical results are compared with analytical solutions.......The formulation presented in this paper is based on the Boundary Element Method (BEM) and implements Kirchhoff’s decomposition into viscous, thermal and acoustic components, which can be treated independently everywhere in the domain except on the boundaries. The acoustic variables with losses...

  9. Beam dynamics in high intensity cyclotrons including neighboring bunch effects: Model, implementation, and application

    Directory of Open Access Journals (Sweden)

    J. J. Yang (杨建俊

    2010-06-01

    Full Text Available Space-charge effects, being one of the most significant collective effects, play an important role in high intensity cyclotrons. However, for cyclotrons with small turn separation, other existing effects are of equal importance. Interactions of radially neighboring bunches are also present, but their combined effects have not yet been investigated in any great detail. In this paper, a new particle in the cell-based self-consistent numerical simulation model is presented for the first time. The model covers neighboring bunch effects and is implemented in the three-dimensional object-oriented parallel code OPAL-cycl, a flavor of the OPAL framework. We discuss this model together with its implementation and validation. Simulation results are presented from the PSI 590 MeV ring cyclotron in the context of the ongoing high intensity upgrade program, which aims to provide a beam power of 1.8 MW (CW at the target destination.

  10. Electron Beam Adjustment in PLATO RTS 2 Including the Effect of Air Gaps

    CERN Document Server

    Lopes, M C; Trindade, A; Rodrigues, P; Peralta, L

    2002-01-01

    Background and Purpose: Beam characterization for electron dose calculations in PLATO RTS 2 treatment planning system requires the tuning of two adjustment parameters: sqx (the initial angular spread) and FMCS (a "fudge" multiple Coulomb scattering parameter). This work provides a set of suggestions to optimise electron dose calculations with PLATO, taking into account the effect of air gaps between the electron applicator and the patient skin. Material and Methods: Two adjustment criteria have been followed: one which uses just one input data set corresponding to the standard (null) air gap and another one that takes into account the whole range of clinically used distances between the electron applicator and the patient surface. The adjusted values of sqx were compared with experimental data and GEANT3 Monte Carlo code results. A systematic study has been carried out of the effect of both adjustment parameters on electron dose calculations in water. Comparisons of dose distributions and point dose values ha...

  11. Complete Loss and Thermal Model of Power Semiconductors Including Device Rating Information

    DEFF Research Database (Denmark)

    Ma, Ke; Bahman, Amir Sajjad; Beczkowski, Szymon

    2015-01-01

    models, only the electrical loadings are focused and treated as design variables, while the device rating is normally pre-defined by experience with limited design flexibility. Consequently, a more complete loss and thermal model is proposed in this paper, which takes into account not only the electrical...

  12. Numerical models of single- and double-negative metamaterials including viscous and thermal losses

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Sánchez-Dehesa, José

    2017-01-01

    detailed understanding on how viscous and thermal losses affect the setups at different frequencies. The modeling of a simpler single-negative metamaterial also broadens this overview. Both setups have been modeled with quadratic BEM meshes. Each sample, scaled at two different sizes, has been represented...

  13. Toward including the effect of manufacturing processes in the pre-estimated losses of the switched reluctance motor

    Directory of Open Access Journals (Sweden)

    Eyhab El-Kharahi

    2015-03-01

    Full Text Available The estimation of losses plays a key role in the process of building any electrical machine. How to estimate those losses while designing any machine; by obtaining the characteristic of the electrical steel from the catalogue and calculate the losses. However, this way is inaccurate since the electrical steel performs several manufacturing processes during the process of building any machine, which affects directly the magnetic property of the electrical steel and accordingly the characteristic of the electrical steel will be affected. That means the B–H curve of the steel that was obtained from the catalogue will be changed. Moreover, during loading and rotating the machine, some important changes occur to the B–H characteristic of the electrical steel such as the stress on the laminated iron. Accordingly, the pre-estimated losses are completely far from the actual losses because they were estimated based on the data of the electrical steel obtained from the catalogue. So in order to estimate the losses precisely significant factors of the manufacturing processes must be included. The paper introduces the systematic estimation of the losses including the effect of one of the manufacturing factors. Similarly, any other manufacturing factor can be included in the pre-designed losses estimations.

  14. Privacy-preserving smart meter control strategy including energy storage losses

    OpenAIRE

    Avula, Chinni Venkata Ramana R.; Oechtering, Tobias J.; Månsson, Daniel

    2018-01-01

    Privacy-preserving smart meter control strategies proposed in the literature so far make some ideal assumptions such as instantaneous control without delay, lossless energy storage systems etc. In this paper, we present a one-step-ahead predictive control strategy using Bayesian risk to measure and control privacy leakage with an energy storage system. The controller estimates energy state using a three-circuit energy storage model to account for steady-state energy losses. With numerical exp...

  15. Preliminary design of the beam loss monitor system for the Advanced Photon Source

    International Nuclear Information System (INIS)

    Patterson, D.R.

    1992-01-01

    The preliminary design of the beam loss monitor for the ANL Advanced Photon Source is based on the use of an air dielectric coaxial cable as a long ionization chamber. Each coaxial cable section uses a high sensitivity DC current-to-voltage converter with both linear and integrating ranges. Pulse timing circuits determine the positions of individual losses by measuring the time at which the resulting voltage pulses arrive at the beginning of the coaxial ionization chamber. A possible timing ambiguity can be removed by correlating the particle bunch timing with the resulting voltage pulse timing. Measurements have shown that pulse rise times less than 15 nanoseconds can be obtained, so that determining loss locations to better than 7 feet may be possible. Best performance may be obtained when 500 VDC is applied to a 50-ohm, 7/8-inch air dielectric coaxial cable filled with approximately 8 psig of a 95% argon, 5% carbon dioxide gas mixture. Cable lengths will be between 100 and 300 feet long, depending on the part of the accelerator being monitored

  16. A Two-Dimensional Modeling Procedure to Estimate the Loss Equivalent Resistance Including the Saturation Effect

    Directory of Open Access Journals (Sweden)

    Rosa Ana Salas

    2013-11-01

    Full Text Available We propose a modeling procedure specifically designed for a ferrite inductor excited by a waveform in time domain. We estimate the loss resistance in the core (parameter of the electrical model of the inductor by means of a Finite Element Method in 2D which leads to significant computational advantages over the 3D model. The methodology is validated for an RM (rectangular modulus ferrite core working in the linear and the saturation regions. Excellent agreement is found between the experimental data and the computational results.

  17. Retrograde amnesia produced by electron beam exposure: causal parameters and duration of memory loss

    International Nuclear Information System (INIS)

    Wheeler, T.G.; Hardy, K.A.

    1985-01-01

    The production of retrograde amnesia (RA) upon electron beam exposure has been investigated. RA production was evaluated using a single-trial avoidance task across a 10 4 dose range for 10-, 1-, and 0.1-μsec pulsed exposures. The dose-response curve obtained at each pulse duration showed significant RA production. The most effective dose range was 0.1-10 rad at a dose rate of 10 6 rad/sec. By employing a 10 rad (10 6 rad/sec) pulse, a memory loss of the events occurring in the previous 4 sec was demonstrated. The conclusion was that the RA effect might be due to sensory activation which provided a novel stimulus that masked previous stimuli

  18. Energy deposition in TEVATRON magnets from beam losses in interaction regions

    International Nuclear Information System (INIS)

    Ginneken, A.V.

    1988-10-01

    In addition to interacting in the detector, particles produced at an interaction region also deposit energy, with less desirable consequences, in magnets and other components of the accelerator. This note briefly assesses the damage potential of these (essentially unavoidable) beam losses from the viewpoint of quenching of superconducting magnets in an upgraded Tevatron, specifically for the 1 TeV p-/ovrreverse arrowstring/p option with a luminosity of 10 31 cm/sup - 2/ sec -1 , through the results carry more generality. Related issues such as radiation damage to detector electronics or other components are not addressed here. These are thought to be less problematic at the Tevatron, as in thus far supported by operational experience. 8 refs., 10 figs

  19. Capture from pair production as a beam loss mechanism for heavy ions at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Feinberg, B.; Belkacem, A.; Claytor, N.; Dinneen, T.; Gould, H. [Lawrence Berkeley National Lab., CA (United States). Accelerator and Fusion Research Div.

    1997-05-01

    Electron capture from electron-positron pair production is predicted to be a major source of beam loss for the heaviest ions at RHIC. Achieving the highest luminosity thus requires an understanding of the capture process. The authors report measurements of this process at Brookhaven National Laboratory`s AGS using 10.8 GeV/nucleon Au{sup 79+} projectiles on Au targets. Capture from pair production is a process in which the very high electromagnetic field involved in the collision of two relativistic heavy ions results in the production of an electron-positron pair with the capture of the electron by one of the ions. There are many theoretical papers published on capture from pair production with discrepancies between predicted cross sections. The experimental results are compared to theory and to previous experiments at 1 GeV/nucleon. The implications of extrapolations to RHIC energies are presented.

  20. Retrograde amnesia produced by electron beam exposure: causal parameters and duration of memory loss. [Rats

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, T.G.; Hardy, K.A.

    1985-01-01

    The production of retrograde amnesia (RA) upon electron beam exposure has been investigated. RA production was evaluated using a single-trial avoidance task across a 10/sup 4/ dose range for 10-, 1-, and 0.1-..mu..sec pulsed exposures. The dose-response curve obtained at each pulse duration showed significant RA production. The most effective dose range was 0.1-10 rad at a dose rate of 10/sup 6/ rad/sec. By employing a 10 rad (10/sup 6/ rad/sec) pulse, a memory loss of the events occurring in the previous 4 sec was demonstrated. The conclusion was that the RA effect might be due to sensory activation which provided a novel stimulus that masked previous stimuli.

  1. Loss of PKCδ results in characteristics of Sjögren's syndrome including salivary gland dysfunction.

    Science.gov (United States)

    Banninger, G P; Cha, S; Said, M S; Pauley, K M; Carter, C J; Onate, M; Pauley, B A; Anderson, S M; Reyland, M E

    2011-09-01

    Chronic infiltration of lymphocytes into the salivary and lacrimal glands of patients with Sjögren's syndrome (SS) leads to destruction of acinar cells and loss of exocrine function. Protein kinase C-delta (PKCδ) is known to play a critical role in B-cell maintenance. Mice in which the PKCδ gene has been disrupted have a loss of B-cell tolerance, multiple organ lymphocytic infiltration, and altered apoptosis. To determine whether PKCδ contributes to the pathogenesis of SS, we quantified changes in indicators of SS in PKCδ-/- mice as a function of age. Salivary gland histology, function, the presence of autoantibodies, and cytokine expression were examined. Submandibular glands were examined for the presence of lymphocytic infiltrates, and the type of infiltrating lymphocyte and cytokine deposition was evaluated by immunohistochemistry. Serum samples were tested by autoantibody screening, which was graded by its staining pattern and intensity. Salivary gland function was determined by saliva collection at various ages. PKCδ-/- mice have reduced salivary gland function, B220+ B-cell infiltration, anti-nuclear antibody production, and elevated IFN-γ in the salivary glands as compared to PKCδ+/+ littermates. PKCδ-/- mice have exocrine gland tissue damage indicative of a SS-like phenotype. © 2011 John Wiley & Sons A/S.

  2. Ion and electron beam effects on kinetic Alfven wave with general loss-cone distribution function-kinetic approach

    International Nuclear Information System (INIS)

    Shukla, Nidhi; Mishra, Ruchi; Varma, P; Tiwari, M S

    2008-01-01

    This work studies the effect of ion and electron beam on kinetic Alfven wave (KAW) with general loss-cone distribution function. The kinetic theory has been adopted to evaluate the dispersion relation and damping rate of the wave in the presence of loss-cone distribution indices J. The variations in wave frequency ω and damping rate with perpendicular wave number k perpendicular ρ i (k perpendicular is perpendicular wave number and ρ i is ion gyroradius) and parallel wave number k parallel are studied. It is found that the distribution index J and ion beam velocity enhance the wave frequency at lower k perpendicular ρ i , whereas the electron beam velocity enhances the wave frequency at higher k perpendicular ρ i . The calculated values of frequency correspond to the observed values in the range 0.1-4 Hz. Increase in damping rate due to higher distribution indices J and ion beam velocity is observed. The effect of electron beam is to reduce the damping rate at higher k perpendicular ρ i . The plasma parameters appropriate to plasma sheet boundary layer are used. The results may explain the transfer of Poynting flux from the magnetosphere to the ionosphere. It is also found that in the presence of the loss-cone distribution function the ion beam becomes a sensitive parameter to reduce the Poynting flux of KAW propagating towards the ionosphere

  3. Commissioning and first operational experience of the ATLAS beam conditions and loss monitors based on pCVD diamond sensors

    Science.gov (United States)

    Gorišek, A.; Atlas Bcm Collaboration

    2010-05-01

    Primary goal of ATLAS Beam Condition and Beam Loss Monitors based on polycrystalline chemical vapor deposition (pCVD) diamonds is to protect the ATLAS inner silicon detectors from beam incidents. The sensor material was chosen due to its radiation hardness. The first one, ATLAS Beam Condition Monitor (BCM) utilizes fast front end amplifiers and processing electronics capable of handling events in real time and storing data in circular buffer thousand LHC turns deep for post-mortem analysis. There are eight detectors installed, four on each side of interaction point (IP) of ATLAS spectrometer. Due to fast timing and high efficiency for detecting single particles BCM will also provide valuable information on instantaneous luminosity. The second system, ATLAS Beam Loss Monitor (BLM) is adopted after similar system developed in the LHC beam instrumentation group with detectors replaced with the pCVD diamonds, with six of such detectors on each side of the IP. In this contribution the design and commissioning of the above two systems will be presented and results of the first operational experience will be shown as obtained in combined ATLAS framework both with the first LHC beam and commissioning cosmic ray runs.

  4. Numerical models of single- and double-negative metamaterials including viscous and thermal losses

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Sánchez-Dehesa, José

    2017-01-01

    Negative index acoustic metamaterials are artificial structures made of subwavelength units arranged in a lattice, whose effective acoustic parameters, bulk modulus and mass density, can be negative. In these materials, sound waves propagate inside the periodic structure, assumed rigid, showing...... extraordinary properties. We are interested in two particular cases: a double-negative metamaterial, where both parameters are negative at some frequencies, and a single-negative metamaterial with negative bulk modulus within a broader frequency band. In previous research involving the double-negative...... detailed understanding on how viscous and thermal losses affect the setups at different frequencies. The modeling of a simpler single-negative metamaterial also broadens this overview. Both setups have been modeled with quadratic BEM meshes. Each sample, scaled at two different sizes, has been represented...

  5. Distributed soil loss estimation system including ephemeral gully development and tillage erosion

    Directory of Open Access Journals (Sweden)

    D. A. N. Vieira

    2015-03-01

    Full Text Available A new modelling system is being developed to provide spatially-distributed runoff and soil erosion predictions for conservation planning that integrates the 2D grid-based variant of the Revised Universal Soil Loss Equation, version 2 model (RUSLER, the Ephemeral Gully Erosion Estimator (EphGEE, and the Tillage Erosion and Landscape Evolution Model (TELEM. Digital representations of the area of interest (field, farm or entire watershed are created using high-resolution topography and data retrieved from established databases of soil properties, climate, and agricultural operations. The system utilizes a library of processing tools (LibRaster to deduce surface drainage from topography, determine the location of potential ephemeral gullies, and subdivide the study area into catchments for calculations of runoff and sheet-and-rill erosion using RUSLER. EphGEE computes gully evolution based on local soil erodibility and flow and sediment transport conditions. Annual tillage-induced morphological changes are computed separately by TELEM.

  6. OPERATIONAL EXPERIENCE WITH FAST FIBER-OPTIC BEAM LOSS MONITORS FOR THE ADVANCED PHOTON SOURCE STORAGE RING SUPERCONDUCTING UNDULATORS

    Energy Technology Data Exchange (ETDEWEB)

    Dooling, J.; Harkay, K.; Sajaev, V.; Shang, H.

    2017-06-25

    Fast fiber-optic (FFO) beam loss monitors (BLMs) installed with the first two superconducting undulators (SCUs) in the Advanced Photon Source storage ring have proven to be a useful diagnostic for measuring deposited charge (energy) during rapid beam loss events. The first set of FFOBLMs were installed outside the cryostat of the short SCU, a 0.33-m long device, above and below the beam centerline. The second set are mounted with the first 1.1-mlong SCU within the cryostat, on the outboard and inboard sides of the vacuum chamber. The next 1.1-m-long SCU is scheduled to replace the short SCU later in 2016 and will be fitted with FFOBLMs in a manner similar to original 1.1-m device. The FFOBLMs were employed to set timing and voltage for the abort kicker (AK) system. The AK helps to prevent quenching of the SCUs during beam dumps [1] by directing the beam away from the SC magnet windings. The AK is triggered by the Machine Protection System (MPS). In cases when the AK fails to prevent quenching, the FFOBLMs show that losses often begin before detection by the MPS.

  7. 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,...

  8. Measurement profiles of nano-scale ion beam for optimized radiation energy losses

    International Nuclear Information System (INIS)

    Woo, T.H.; Cho, H.S.

    2011-01-01

    The behavior of charged particles is investigated for nano-scale ion beam therapy using a medical accelerator. Computational work is performed for the Bragg-peak simulation, which is focused on human organ material of pancreas and thyroid. The Results show that the trends of the dose have several different kinds of distributions. Before constructing a heavy ion collider, this study can give us the reliability of the therapeutic effect. Realistic treatment using human organs is calculated in a simple and cost effective manner using the computational code, the Stopping and Range of Ions in Matter 2008 (SRIM 2008). Considering the safety of the therapy, it is suggested to give a patient orient planning of the cancer therapy. The energy losses in ionization and phonon are analyzed, which are the behaviors in the molecular level nano-scopic investigation. The different fluctuations are shown at 150 MeV, where the lowest temperature is found in proton and pancreas case. Finally, the protocol for the radiation therapy is constructed by the simulation in which the procedure for a better therapy is selected. An experimental measurement incorporated with the simulations could be programmed by this protocol.

  9. Simulation of AZ-PN100 resist pattern fluctuation in X-ray lithography, including synchrotron beam polarization

    International Nuclear Information System (INIS)

    Scheckler, E.W.; Ogawa, Taro; Tanaka, Toshihiko; Takeda, Eiji; Oizumi, Hiroaki.

    1993-01-01

    A new simulation model for nanometer-scale pattern fluctuation in X-ray lithography is presented and applied to a study of AZ-PN100 negative chemical amplification resist. The exposure simulation considers polarized photons from a synchrotron radiation (SR) source. Monte Carlo simulation of Auger and photoelectron generation is followed by electron scattering simulation to determine the deposited energy distribution at the nanometer scale, including beam polarization effects. An acid-catalyst random walk model simulates the post-exposure bake (PEB) step. Fourier transform infrared (FTIR) spectroscopy and developed resist thickness measurements are used to fit PEB and rate models for AZ-PN100. A polymer removal model for development simulation predicts the macroscopic resist shape and pattern roughness. The simulated 3σ linewidth variation is in excess of 24 nm. Simulation also shows a detrimental effect if the beam polarization is perpendicular to the line. Simulation assuming a theoretical ideal exposure yields a 50 nm minimum line for standard process conditions. (author)

  10. Bending, longitudinal and torsional wave transmission on Euler-Bernoulli and Timoshenko beams with high propagation losses.

    Science.gov (United States)

    Wang, X; Hopkins, C

    2016-10-01

    Advanced Statistical Energy Analysis (ASEA) is used to predict vibration transmission across coupled beams which support multiple wave types up to high frequencies where Timoshenko theory is valid. Bending-longitudinal and bending-torsional models are considered for an L-junction and rectangular beam frame. Comparisons are made with measurements, Finite Element Methods (FEM) and Statistical Energy Analysis (SEA). When beams support at least two local modes for each wave type in a frequency band and the modal overlap factor is at least 0.1, measurements and FEM have relatively smooth curves. Agreement between measurements, FEM, and ASEA demonstrates that ASEA is able to predict high propagation losses which are not accounted for with SEA. These propagation losses tend to become more important at high frequencies with relatively high internal loss factors and can occur when there is more than one wave type. At such high frequencies, Timoshenko theory, rather than Euler-Bernoulli theory, is often required. Timoshenko theory is incorporated in ASEA and SEA using wave theory transmission coefficients derived assuming Euler-Bernoulli theory, but using Timoshenko group velocity when calculating coupling loss factors. The changeover between theories is appropriate above the frequency where there is a 26% difference between Euler-Bernoulli and Timoshenko group velocities.

  11. 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...

  12. 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...

  13. Beam-Loss Driven Design Optimization for the Spallation Neutron Source (SNS) Ring

    International Nuclear Information System (INIS)

    Wei, J.

    1999-01-01

    This paper summarizes three-state design optimization for the Spallation Neutron Source (SNS) ring: linear machine design (lattice, aperture, injection, magnet field errors and misalignment), beam core manipulation (painting, space charge, instabilities, RF requirements), and beam halo consideration (collimation, envelope variation, e-p issues etc.)

  14. Fabrication of low-loss silicon-on-oxidized-porous-silicon strip waveguide using focused proton-beam irradiation

    OpenAIRE

    Teo, EJ; Bettiol, AA; Yang, P; Breese, MBH; Xiong, BQ; Mashanovich, GZ; Headley, WR; Reed, GT

    2009-01-01

    we have successfully fabricated low-loss silicon-on-oxidized-porous-silicon (SOPS) strip waveguides with high-index contrast using focused proton-beam irradiation and electrochemical etching. Smooth surface quality with rms roughness of 3.1 nm is achieved for a fluence of 1 x 10(15)/cm(2) after postoxidation treatment. Optical characterization at a wavelength of 1550 nm shows a loss of 1.1 +/- 0.4 dB/cm and 1.2 +/- 0.4 dB/cm in TE and TM polarization respectively, which we believe is the lowe...

  15. Fabrication of low-loss silicon-on-oxidized-porous-silicon strip waveguide using focused proton-beam irradiation.

    Science.gov (United States)

    Teo, E J; Bettiol, A A; Yang, P; Breese, M B H; Xiong, B Q; Mashanovich, G Z; Headley, W R; Reed, G T

    2009-03-01

    We have successfully fabricated low-loss silicon-on-oxidized-porous-silicon (SOPS) strip waveguides with high-index contrast using focused proton-beam irradiation and electrochemical etching. Smooth surface quality with rms roughness of 3.1 nm is achieved for a fluence of 1x10(15)/cm(2) after postoxidation treatment. Optical characterization at a wavelength of 1550 nm shows a loss of 1.1+/-0.4 dB/cm and 1.2+/-0.4 dB/cm in TE and TM polarization respectively, which we believe is the lowest reported loss for SOPS waveguides. This opens up new opportunities for all-silicon-based optoelectronics applications.

  16. 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...

  17. A Novel Millimeter-Wave, Low-Loss, Electronically Controlled Phase Shifter for Monolithic, Beam-Steering Phased-Array Antenna Application

    National Research Council Canada - National Science Library

    Sarabandi, Kamal

    1997-01-01

    The purpose of this document is to summarize the accomplishments made on the project entitled "A Novel Millimeter-Wave, Low-Loss, Electronically Controlled Phase Shifter for Monolithic, Beam-Steering...

  18. 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.

  19. 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.

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

    OpenAIRE

    Baer, Tobias; Wenninger, Jorg; Elsen, Eckhard

    2013-01-01

    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...

  1. Simulation of multicomponent losses in electron beam melting and refining at varying scan frequencies

    International Nuclear Information System (INIS)

    Powell, A.; Szekely, J.; Van Den Avyle, J.; Damkroger, B.

    1995-01-01

    A two-stage model is presented to describe alloy element evaporation rates from molten metal due to transient local heating by an electron beam. The first stage is a simulation of transient phenomena near the melt surface due to periodic heating by a scanning beam, the output of which is the relationship between operating parameters, surface temperature, and evaporation rate. At high scan rates, this can be done using a simple one-dimensional heat transfer model of the surface layer; at lower scan rates, a more complex three-dimensional model with fluid flow and periodic boundary conditions is necessary. The second stage couples this evaporation-surface temperature relationship with a larger steady state heat transfer and fluid flow model of an entire melting hearth or mold, in order to calculate local and total evaporation rates. Predictions are compared with experimental results from Sandia's 310-kW electron beam melting furnace, in which evaporation rates and vapor compositions were studied in pure titanium and Ti-6%Al-4%V alloy. Evaporation rates were estimated from rate of condensation on a substrate held over the hearth, and were characterized as a function of beam power (150 and 225 kW), scan frequency (30, 115 and 450 Hz) and background pressure (10 -3 , 10 -4 and 10 -5 torr)

  2. 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

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

    International Nuclear Information System (INIS)

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

    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. After an integrated luminosity of a few fb -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 CCE in

  4. Dietary adherence and acceptability of five different diets, including vegan and vegetarian diets, for weight loss: The New DIETs study.

    Science.gov (United States)

    Moore, Wendy J; McGrievy, Michael E; Turner-McGrievy, Gabrielle M

    2015-12-01

    The goal of the present study was to examine dietary adherence and acceptability among participants from the New DIETs study who were randomized to one of four plant-based diets (vegan, vegetarian, pesco-vegetarian, semi-vegetarian) or an omnivore diet. Primary outcomes at two- and six months included dietary adherence (24-hour dietary recalls), weight loss and changes in animal product intake (mg cholesterol) by adherence status, Three-Factor Eating Questionnaire (TFEQ), Power of Food Scale (PFS), dietary acceptability (Food Acceptability Questionnaire), and impact of diet preference on adherence. No differences were found in dietary adherence or changes in FAQ, TFEQ, or PFS among the groups. At six months, non-adherent vegan and vegetarian participants (n=16) had a significantly greater decrease in cholesterol intake (-190.2 ± 199.2 mg) than non-adherent pesco-vegetarian/semi-vegetarian (n=15, -2.3 ± 200.3 mg, P=0.02) or omnivore participants (n=7, 17.0 ± 36.0, P=0.04). Non-adherent vegan/vegetarian participants lost significantly more weight at six months (-6.0 ± 6.7%) than non-adherent omnivore participants (-0.4 ± 0.6%, P=0.04). Dietary preference had no impact on adherence at six months. Due to equal rates of adherence and acceptability among the diet groups, instructing participants to follow vegan or vegetarian diets may have a greater impact on weight loss and animal product intake than providing instruction in more moderate approaches even among non-adherent participants. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Successful weight loss maintenance includes long-term increased meal responses of GLP-1 and PYY3-36

    DEFF Research Database (Denmark)

    Iepsen, Eva W; Lundgren, Julie; Holst, Jens J

    2016-01-01

    at week 52. Glucagon levels were unaffected by weight loss. CONCLUSIONS: Meal responses of GLP-1 and PYY3-36 remained increased 1 year after weight maintenance, whereas ghrelin and GIP reverted toward before-weight loss values. Thus, an increase in appetite inhibitory mechanisms and a partly decrease...... in appetite-stimulating mechanisms appear to contribute to successful long-term weight loss maintenance.......-week very low-calorie diet (800kcal/day). After weight loss, participants entered a 52-week weight maintenance protocol. Plasma levels of GLP-1, PYY3-36, ghrelin, GIP and glucagon during a 600-kcal meal were measured before weight loss, after weight loss and after 1 year of weight maintenance. Area...

  6. Challenges of arbitrary waveform signal detection by Silicon Photomultipliers as readout for Cherenkov fibre based beam loss monitoring systems

    CERN Document Server

    Vinogradov, Sergey; Nebot del Busto, Eduardo; Kastriotou, Maria; Welsch, Carsten P

    2016-01-01

    Silicon Photomultipliers (SiPMs) are well recognised as very competitive photodetectors due to their exceptional photon number and time resolution, room-temperature low-voltage operation, insensitivity to magnetic fields, compactness, and robustness. Detection of weak light pulses of nanosecond time scale appears to be the best area for SiPM applications because in this case most of the SiPM drawbacks have a rather limited effect on its performance. In contrast to the more typical scintillation and Cherenkov detection applications, which demand information on the number of photons and/or the arrival time of the light pulse only, beam loss monitoring (BLM) systems utilising Cherenkov fibres with photodetector readout have to precisely reconstruct the temporal profile of the light pulse. This is a rather challenging task for any photon detector especially taking into account the high dynamic range of incident signals (100K – 1M) from a few photons to a few percents of destructive losses in a beam line and pre...

  7. A Numerical Model of an Acoustic Metamaterial Using the Boundary Element Method Including Viscous and Thermal Losses

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Andersen, Peter Risby; Jensen, Jakob Søndergaard

    2016-01-01

    In recent years, boundary element method (BEM) and finite element method (FEM) implementations of acoustics in fluids with viscous and thermal losses have been developed. They are based on the linearized Navier–Stokes equations with no flow. In this paper, such models with acoustic losses are app...

  8. How can the co-ordinate transformation method of beam matching be extended to include separately labelled collimators?

    Science.gov (United States)

    Morgan-Fletcher, S; McKenzie, A L

    1996-03-01

    The problem of matching radiation beams was tackled by Siddon in 1980 using co-ordinate transformations. Since then, the need to distinguish between individual collimators in prescriptions of treatment set-up, brought about by the widespread use of 3-D treatment planning systems and asymmetric fields, as well as a reversal of the rotation sense in the turntable co-ordinate system proposed by the International Electrotechnical Commission, have made it necessary to revisit this particular problem. This paper builds upon Siddon's general equations for the particular case of matching beams, and derives expressions for calculating treatment-unit settings which may be used in a computer program without the need to perform matrix manipulation. The expression treat the individual collimator jaws separately.

  9. Slowing the rate of loss of mineral wetlands on human dominated landscapes - Diversification of farmers markets to include carbon (Invited)

    Science.gov (United States)

    Creed, I. F.; Badiou, P.; Lobb, D.

    2013-12-01

    Canada is the fourth-largest exporter of agriculture and agri-food products in the world (exports valued at 28B), but instability of agriculture markets can make it difficult for farmers to cope with variability, and new mechanisms are needed for farmers to achieve economic stability. Capitalizing on carbon markets will help farmers achieve environmentally sustainable economic performance. In order to have a viable carbon market, governments and industries need to know what the carbon capital is and what potential there is for growth, and farmers need financial incentives that will not only allow them to conserve existing wetlands but that will also enable them to restore wetlands while making a living. In southern Ontario, farmers' needs to maximize the return on investment on marginal lands have resulted in loss of 70-90% of wetlands, making this region one of the most threatened region in terms of wetland degradation and loss in Canada. Our project establishes the role that mineral wetlands have in the net carbon balance by contributing insight into the potential benefits to carbon management provided by wetland restoration efforts in these highly degraded landscapes. The goal was to establish the magnitude of carbon offsets that could be achieved through wetland conservation (securing existing carbon stocks) and restoration (creating new carbon stocks). The experimental design was to focus on (1) small (0.2-2.0 ha) and (2) isolated (no inflow or outflow) mineral wetlands with the greatest restoration potential that included (3) a range of restoration ages (drained (0 yr), 3 yr, 6 yr, 12 yr, 20 yr, 35 yr, intact marshes) to capture potential changes in rates of carbon sequestration with restoration age of wetland. From each wetland, wetland soil carbon pools samples were collected at four positions: centre of wetland (open-water); emergent vegetation zone; wet meadow zone where flooding often occurs (i.e., high water mark); and upland where flooding rarely

  10. Sudden hearing loss and vertigo after tooth extraction successfully treated with combined therapy including HBO2: a case report.

    Science.gov (United States)

    Yilmaz, Huseyin Baki; Erdogan, Raziye Banu Atalay; Paksoy, Mustafa; Sanli, Arif

    2015-01-01

    Sudden sensorineural hearing loss (SSNHL) is a decrease in hearing of at least 30 dB that occurs within three days and which affects at least three consecutive frequencies in either ear or both ears. This case report describes a woman who had sudden hearing loss and vertigo in the right ear after tooth extraction. As the first-line therapy, systemic and intratympanic steroid injections were used this led to a slight improvement; however, the majority of improvement in hearing was not observed until hyperbaric oxygen (HBO2) therapy was instituted on the 20th day of hearing loss. Sudden hearing loss and vertigo after tooth extraction is an otologic emergency and early evaluation and treatment are effective. HBO2, although employed beyond the Undersea and Hyperbaric Medical Society's recommended initial 14 days of symptom onset, very was effective for this particular case.

  11. 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.

  12. 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.

  13. Investigation of Electron Beam Induced Mass Loss of Embedding Media in the Low Voltage STEM

    Czech Academy of Sciences Publication Activity Database

    Novotná, V.; Hrubanová, Kamila; Nebesářová, J.; Krzyžánek, Vladislav

    2014-01-01

    Roč. 20, S3 (2014), s. 1270-1271 ISSN 1431-9276 R&D Projects: GA MŠk EE.2.3.20.0103; GA MŠk(CZ) LO1212; GA ČR(CZ) GA14-20012S; GA TA ČR TE01020118 Institutional support: RVO:68081731 Keywords : mass loss * mass-thickness measurement * low voltage STEM Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.877, year: 2014

  14. Loss of PKCδ results in characteristics of Sjögren’s syndrome including salivary gland dysfunction

    OpenAIRE

    Banninger, Gregg P.; Cha, Seunghee; Said, M Sherif; Pauley, Kaleb M.; Carter, Cristan J.; Ornate, Mairelys; Pauley, Brad A.; Anderson, Steven M.; Reyland, Mary E.

    2011-01-01

    Chronic infiltration of lymphocytes into the salivary and lacrimal glands of Sjögren’s Syndrome patients leads to destruction of acinar cells and loss of exocrine function. Protein kinase C-delta (PKCδ) is known to play a critical role in B cell maintenance. Mice in which the PKCδ gene has been disrupted have a loss of B cell tolerance, multiple organ lymphocytic infiltration, and altered apoptosis. To determine if PKCδ contributes to the pathogenesis of Sjögren’s Syndrome, we quantified chan...

  15. Studies of the Response of the Prototype CMS Hadron Calorimeter, Including Magnetic Field Effects, to Pion, Electron, and Muon Beams

    CERN Document Server

    Abramov, V.V.; Akchurin, N.; Atanasov, I.; Baiatian, G.; Ball, A.; Banerjee, S.; de Barbaro, P.; Barnes, V.; Bencze, G.; Bodek, A.; Booke, M.; Budd, H.; Cremaldi, L.; Cushman, P.; Dugad, S.R.; Dimitrov, L.; Dyshkant, A.; Elias, J.; Evdokimov, V.N.; Fong, D.; Freeman, J.; Genchev, V.; Goncharov, P.I.; Green, D.; Gurtu, A.; Hagopian, V.; Iaydjiev, P.; Korneev, Yu.; Krinitsyn, A.; Krishnaswami, G.; Krishnaswamy, M.R.; Kryshkin, V.; Kunori, S.; Laasanen, A.; Lazic, D.; Levchuk, L.; Litov, L.; Mondal, N.K.; Moulik, T.; Narasimham, V.S.; Nemashkalo, A.; Onel, Y.; Petrov, P.; Petukhov, Yu.; Piperov, S.; Popov, V.; Reidy, J.; Ronzhin, A.; Ruchti, R.; Singh, J.B.; Shen, Q.; Sirunyan, A.; Skuja, A.; Skup, E.; Sorokin, P.; Sudhakar, K.; Summers, D.; Szoncso, F.; Tereshenko, S.I.; Timmermans, C.; Tonwar, S.C.; Turchanovich, L.; Tyukov, V.; Volodko, A.; Yukaev, A.; Zaitchenko, A.; Zatserklyaniy, A.; Korneev, Yu.

    2001-01-01

    We report on the response of a prototype CMS hadron calorimeter module to charged particle beams of pions, muons, and electrons with momenta up to 375 GeV/c. The data were taken at the H2 and H4 beamlines at CERN in 1995 and 1996. The prototype sampling calorimeter used copper absorber plates and scintillator tiles with wavelength shifting fibers for readout. The effects of a magnetic field of up to 3 Tesla on the response of the calorimeter to muons, electrons, and pions are presented, and the effects of an upstream lead tungstate crystal electromagnetic calorimeter on the linearity and energy resolution of the combined calorimetric system to hadrons are evaluated. The results are compared with Monte Carlo simulations and are used to optimize the choice of total absorber depth, sampling frequency, and longitudinal readout segmentation.

  16. Retrograde amnesia produced by electron beam exposure: casual parameters and duration of memory loss. Final report for November 84

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, T.G.; Hardy, K.A.

    1985-01-01

    The production of retrograde amnesia (RA) upon electron-beam exposure was investigated. RA production was evaluated using a single-trial avoidance task for 10, 1, and 0.1 microsecond pulsed exposures. The dose-response curve obtained at each pulse duration showed significant RA production. The most effective dose range was 0.1-10 rad at a dose rate of 1,000,000 rad/sec. By employing a 10 rad (1,000,000 rad/s) pulse, a memory loss of the events occurring in the previous 4 sec was demonstrated. The conclusion was that the RA effect might be due to sensory system activation which provided a novel stimulus that masked previous stimuli.

  17. Center-size as a predictor of weight-loss outcome in multicenter trials including a low-calorie diet

    DEFF Research Database (Denmark)

    Gasteyger, Christoph Rolf; Christensen, Robin; Larsen, Thomas Meinert

    2010-01-01

    weight loss. This is a post hoc analysis of an existing database: 701 obese subjects (77% women, 23% men, mean BMI: 38.9 kg/m(2)) were enrolled at 22 sites (4-85 subjects/site) in five countries to follow a LCD providing 800-1,000 kcal/day during 8 weeks. The main outcome measure was the percentage...

  18. Beam backgrounds in the ATLAS detector during LHC loss map tests at beta*=40cm and beta*=80cm at Ebeam=6.5 TeV

    CERN Document Server

    The ATLAS collaboration

    2017-01-01

    In this note the beam-background measurements with the ATLAS detector during lossmap tests of the LHC are described. Loss maps taken at beta*=40 cm and the normal 2015 setting of beta*=80 cm are compared. In the first case several collimator settings were explored, resulting in significant changes of beam backgrounds in ATLAS. Besides the studies of the dependence of background on collimation, which are important for optimisation of the LHC performance, these tests provide a clean environment to study the relative importance of beam halo losses on the experiment. The results show that the halo-related component of beam background in ATLAS decreases exponentially with increasing aperture of the tertiary collimators, the slope in terms of nominal sigma being about -0.5. From the data it is also shown that in normal operation conditions of LHC run 2 the beam halo losses contribute at most at the percent level to the total background, the dominant part coming from beam-gas interactions. The data are also used to ...

  19. 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...

  20. Rifaximin and midodrine improve clinical outcome in refractory ascites including renal function, weight loss, and short-term survival.

    Science.gov (United States)

    Hanafy, Amr S; Hassaneen, Ahmad M

    2016-12-01

    The occurrence of refractory ascites in nearly 17% of patients with decompensated cirrhosis is an unresolved issue. Advanced liver disease, functional renal impairment, and vascular insensitivity to vasopressors are the main causes of its refractoriness. Therefore, the aim of this study was to evaluate the impact on diuresis, weight loss, and short-term survival if midodrine and rifaximin were added to the diuretic therapy (DT). The study evaluated the eligibility of 650 patients with cirrhosis and refractory ascites who were selected during the period from November 2011 to May 2015. A total of 50 patients were excluded and finally 600 were selected and divided into the following groups: patients exposed to DT (n=200) as a control group, or DT with midodrine and rifaximin group (n=400). Body weight, mean arterial pressure, and glomerular filtration rate were determined. Plasma renin and aldosterone were also determined. Follow-up was performed after 2, 6, and 12 weeks, and then every 2 months for 24 months. The mean arterial pressure was significantly higher in the midodrine and rifaximin group (P=0.000), and there was a highly significant weight loss after 12 weeks (12.5 kg) (P=0.000), a highly significant increase in serum sodium, urine output, and urinary sodium excretion (P=0.000), and creatinine clearance was more reduced in the control group. With rifaximin and midodrine, a complete response occurred in 310 (78%) patients, a partial response in 72 (18%), and no response in 18 (4%) versus 30 (15%), 110 (55%), and 60 (30%) in the control group, respectively (P=0.000). Midodrine and rifaximin significantly reduced paracentesis needs when compared with the controls (18 study patients vs. 75 DT-only patients, P=0.000). Adding rifaximin and midodrine to DT enhanced diuresis in refractory ascites with improved systemic, renal hemodynamics and short-term survival.

  1. Detailed magnetic model simulations of the H- injection chicane magnets for the CERN PS Booster Upgrade, including eddy currents and influence on beam dynamics

    CERN Document Server

    Benedetto, E; Borburgh, J; Carli, C; Martini, M; Forte, V

    2014-01-01

    The CERN PS Booster will be upgraded with an H- injection system. The chicanemagnets for the injection bump ramp-down in 5 ms and generate eddy currents in the inconel vacuum chamber which perturb the homogeneity of the magnetic field. The multipolar field components are extracted from 3D OPERA simulations and are included in the lattice model. The -beating correction is computed all along the ramp and complete tracking simulations including space-charge are performed to evaluate the impact of these perturbations and correction on beam dynamics.

  2. The combination of vestibular impairment and congenital sensorineural hearing loss predisposes patients to ocular anomalies, including Usher syndrome.

    Science.gov (United States)

    Kletke, S; Batmanabane, V; Dai, T; Vincent, A; Li, S; Gordon, K A; Papsin, B C; Cushing, S L; Héon, E

    2017-07-01

    The co-occurrence of hearing impairment and visual dysfunction is devastating. Most deaf-blind etiologies are genetically determined, the commonest being Usher syndrome (USH). While studies of the congenitally deaf population reveal a variable degree of visual problems, there are no effective ophthalmic screening guidelines. We hypothesized that children with congenital sensorineural hearing loss (SNHL) and vestibular impairment were at an increased risk of having USH. A retrospective chart review of 33 cochlear implants recipients for severe to profound SNHL and measured vestibular dysfunction was performed to determine the ocular phenotype. All the cases had undergone ocular examination and electroretinogram (ERG). Patients with an abnormal ERG underwent genetic testing for USH. We found an underlying ocular abnormality in 81.81% (27/33) of cases; of which 75% had refractive errors, and 50% of those patients showed visual improvement with refractive correction. A total of 14 cases (42.42%; 14/33) had generalized rod-cone dysfunction on ERG suggestive of Usher syndrome type 1, confirmed by mutational analysis. This work shows that adding vestibular impairment as a criterion for requesting an eye exam and adding the ERG to detect USH increases the chances of detecting ocular anomalies, when compared with previous literature focusing only on congenital SNHL. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Incidence of primary hypothyroidism in patients exposed to therapeutic external beam radiation, where radiation portals include a part or whole of the thyroid gland

    Directory of Open Access Journals (Sweden)

    B A Laway

    2012-01-01

    Full Text Available Introduction: Hypothyroidism is a known consequence of external-beam radiotherapy to the neck encompassing a part or whole of the thyroid gland. In this non-randomized prospective study, we have tried to evaluate the response of the thyroid gland to radiation by assessing thyroid function before irradiation and at regular intervals after irradiation. Aims and Objectives: The aim of this study were to assess in the cancer patients, who were exposed to the therapeutic external beam radiation, where radiation portals include a part or whole of the thyroid gland: the incidence of primary hypothyroidism, the time required to become hypothyroid, any relation between the total dose for the development of hypothyroidism, and whether there are any patient or treatment-related factors that are predictive for the development of hypothyroidism, including the use of concurrent chemotherapy. Materials and Methods: This non-randomized, prospective study was conducted for a period of 2 years in which thyroid function was assessed in 59 patients (cases of head and neck cancer, breast cancer, lymphoma patients and other malignancies, who had received radiotherapy to the neck region. 59 euthyroid healthy patients (controls were also taken, who had not received the neck irradiation. These patients/controls were assessed periodically for 2 years. Results: The incidence of hypothyroidism after external beam radiation therapy (EBRT to neck where radiation portals include part or whole of the thyroid gland was 16.94%, seven cases had subclinical hypothyroidism (11.86% and three cases had clinical hypothyroidism (5.08%. Mean time for development of hypothyroidism was 4.5 months. There was no effect of age, gender, primary tumor site, radiation dose and chemotherapy, whether neoadjuvant or concurrent with the development of hypothyroidism. Conclusion: In summary, we found that thyroid dysfunction is a prevalent, yet easily treatable source of morbidity in patients

  4. Numerical and experimental study of a radiotherapy treatment planning system including Monte Carlo calculations: heterogeneities and small beams applications

    International Nuclear Information System (INIS)

    Habib, Bouchra

    2009-09-01

    Improvements relative to the MC dose calculation speed have been made within the European project MAESTRO by the development of the fast MC code PENFAST and within the TELEDOS project by the parallelization of this code. This PhD work, based on these two projects, focuses on the evaluation of the technical and dosimetric performances of the MC code. These issues are crucial before the use of the MC code in clinical applications. First, variance reduction techniques included in the MC code as well as the parallelization of the calculation have been validated and evaluated in terms of gain in the computing time. The second part of this work has exposed a new, fast and accurate method to determine the initial energy spectrum of the accelerator. This spectrum is required for the MC dose calculation. Afterwards, dose calculations with the fast MC code PENFAST have been evaluated under metrological and clinical conditions. The results showed the ability of the MC code to quickly calculate an accurate dose in both photon and electron modes, even in electronic disequilibrium situations. However, this study revealed an uncertainty, in the TPS-MC, in the conversion of the CT image to voxelized geometry which is used for MC dose calculation. The quality of this voxelization may be improved through an artefacts correction software and by including additional materials in the database of the code. (author)

  5. Beam diagnostics for low energy beams

    Directory of Open Access Journals (Sweden)

    J. Harasimowicz

    2012-12-01

    Full Text Available Low-energetic ion and antimatter beams are very attractive for a number of fundamental studies. The diagnostics of such beams, however, is a challenge due to low currents down to only a few thousands of particles per second and significant fraction of energy loss in matter at keV beam energies. A modular set of particle detectors has been developed to suit the particular beam diagnostic needs of the ultralow-energy storage ring (USR at the future facility for low-energy antiproton and ion research, accommodating very low beam intensities at energies down to 20 keV. The detectors include beam-profile monitors based on scintillating screens and secondary electron emission, sensitive Faraday cups for absolute intensity measurements, and capacitive pickups for beam position monitoring. In this paper, the design of all detectors is presented in detail and results from beam measurements are shown. The resolution limits of all detectors are described and options for further improvement summarized. Whilst initially developed for the USR, the instrumentation described in this paper is also well suited for use in other low-intensity, low-energy accelerators, storage rings, and beam lines.

  6. 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 ...

  7. Subjective and objective measurement of the intelligibility of synthesized speech impaired by the very low bit rate STANAG 4591 codec including packet loss

    NARCIS (Netherlands)

    Počta, P.; Beerends, J.G.

    2017-01-01

    This paper deals with the intelligibility of speech coded by the STANAG 4591 standard codec, including packet loss, using synthesized speech input. Both subjective and objective assessments are used. It is shown that this codec significantly degrades intelligibility when compared to a standard

  8. Comparative study between cold plasma and hot plasma with ion beam and loss-cone distribution function by particle aspect approach

    International Nuclear Information System (INIS)

    Patel, Soniya; Varma, P; Tiwari, M S

    2011-01-01

    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.

  9. 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

    Directory of Open Access Journals (Sweden)

    H. Hotchi

    2016-01-01

    Full Text Available 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.

  10. Beam-beam and impedance

    CERN Document Server

    White, S.

    2014-07-17

    As two counter-rotating beams interact they can give rise to coherent dipole modes. Under the influence of impedance these coherent beam-beam modes can couple to higher order head-tail modes and lead to strong instabilities. A fully self-consistent approach including beam-beam and impedance was used to characterize this new coupled mode instability and study possible cures such as a transverse damper and high chromaticity.

  11. Superresolution beams

    CSIR Research Space (South Africa)

    Ngcobo, S

    2012-07-01

    Full Text Available positions of p zeros of intensity distributions on the Gaussian beam, resulting to a generation of TEMp0 beams where there are minimum losses. The LGBs are well-known family of exact orthogonal solutions of free-space paraxial wave equation in cylindrical...

  12. TURTLE with MAD input (Trace Unlimited Rays Through Lumped Elements) -- A computer program for simulating charged particle beam transport systems and DECAY TURTLE including decay calculations

    Energy Technology Data Exchange (ETDEWEB)

    Carey, D.C.

    1999-12-09

    TURTLE is a computer program useful for determining many characteristics of a particle beam once an initial design has been achieved, Charged particle beams are usually designed by adjusting various beam line parameters to obtain desired values of certain elements of a transfer or beam matrix. Such beam line parameters may describe certain magnetic fields and their gradients, lengths and shapes of magnets, spacings between magnetic elements, or the initial beam accepted into the system. For such purposes one typically employs a matrix multiplication and fitting program such as TRANSPORT. TURTLE is designed to be used after TRANSPORT. For convenience of the user, the input formats of the two programs have been made compatible. The use of TURTLE should be restricted to beams with small phase space. The lumped element approximation, described below, precludes the inclusion of the effect of conventional local geometric aberrations (due to large phase space) or fourth and higher order. A reading of the discussion below will indicate clearly the exact uses and limitations of the approach taken in TURTLE.

  13. TURTLE with MAD input (Trace Unlimited Rays Through Lumped Elements) -- A computer program for simulating charged particle beam transport systems and DECAY TURTLE including decay calculations

    International Nuclear Information System (INIS)

    Carey, D.C.

    1999-01-01

    TURTLE is a computer program useful for determining many characteristics of a particle beam once an initial design has been achieved, Charged particle beams are usually designed by adjusting various beam line parameters to obtain desired values of certain elements of a transfer or beam matrix. Such beam line parameters may describe certain magnetic fields and their gradients, lengths and shapes of magnets, spacings between magnetic elements, or the initial beam accepted into the system. For such purposes one typically employs a matrix multiplication and fitting program such as TRANSPORT. TURTLE is designed to be used after TRANSPORT. For convenience of the user, the input formats of the two programs have been made compatible. The use of TURTLE should be restricted to beams with small phase space. The lumped element approximation, described below, precludes the inclusion of the effect of conventional local geometric aberrations (due to large phase space) or fourth and higher order. A reading of the discussion below will indicate clearly the exact uses and limitations of the approach taken in TURTLE

  14. Blanket Module Boil-Off Times during a Loss-of-Coolant Accident - Case 0: with Beam Shutdown only

    International Nuclear Information System (INIS)

    Hamm, L.L.

    1998-01-01

    This report is one of a series of reports that document LBLOCA analyses for the Accelerator Production of Tritium primary blanket Heat Removal system. This report documents the analysis results of a LBLOCA where the accelerator beam is shut off without primary pump trips and neither the RHR nor the cavity flood systems operation

  15. LHC Beam Instrumentation: Beam Profile Measurements (2/3)

    CERN Multimedia

    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. Beam Dynamics Challenges for Future Circular Colliders

    CERN Multimedia

    Zimmermann, Frank

    2004-01-01

    The luminosity of hadron colliders rises with the beam intensity, until some limit is encountered, mostly due to head-on and long-range beam-beam interaction, due to electron cloud, or due to conventional impedance sources. Also beam losses caused by various mechanisms may affect the performance. The limitations can be alleviated, if not overcome, by a proper choice of beam parameters and by dedicated compensation schemes. Examples include alternating crossing at several interaction points, electromagnetic wires, super-bunches, electron lenses, clearing electrodes, and nonlinear collimation. I discuss such mitigating measures and related research efforts, with special emphasis on the LHC and its upgrade.

  17. Nonlinear Dynamic Analysis of an Inclined Timoshenko Beam Subjected to a Moving Mass/Force with Beam’s Weight Included

    Directory of Open Access Journals (Sweden)

    Ahmad Mamandi

    2011-01-01

    Full Text Available In this study, the nonlinear vibrations analysis of an inclined pinned-pinned self-weight Timoshenko beam made of linear, homogenous and isotropic material with a constant cross section and finite length subjected to a traveling mass/force with constant velocity is investigated. The nonlinear coupled partial differential equations of motion for the rotation of warped cross section, longitudinal and transverse displacements are derived using the Hamilton's principle. These nonlinear coupled PDEs are solved by applying the Galerkin's method to obtain dynamic responses of the beam. The dynamic magnification factor and normalized time histories of mid-point of the beam are obtained for various load velocity ratios and the outcome results have been compared to the results with those obtained from linear solution. The influence of the large deflections caused by a stretching effect due to the beam's fixed ends is captured. It was seen that existence of quadratic-cubic nonlinear terms in the nonlinear governing coupled PDEs of motion causes stiffening (hardening behavior of the dynamic responses of the self-weight beam under the act of a traveling mass as well as equivalent concentrated moving force. Furthermore, in a case where the object leaves the beam, its planar motion path is derived and the targeting accuracy is investigated and compared with those from the rigid solution assumption.

  18. 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

    International Nuclear Information System (INIS)

    Santana Leitner, Mario; Fasso, Alberto; Fisher, Alan S.; Nuhn, Heinz D.; Dooling, Jeffrey C.; Berg, William; Yang, Bin. X.

    2010-01-01

    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. (author)

  19. Loss of Drosophila A-type lamin C initially causes tendon abnormality including disintegration of cytoskeleton and nuclear lamina in muscular defects.

    Science.gov (United States)

    Uchino, Ryo; Nonaka, Yu-Ki; Horigome, Tuneyoshi; Sugiyama, Shin; Furukawa, Kazuhiro

    2013-01-01

    Lamins are the major components of nuclear envelope architecture, being required for both the structural and informational roles of the nuclei. Mutations of lamins cause a spectrum of diseases in humans, including muscular dystrophy. We report here that the loss of the A-type lamin gene, lamin C in Drosophila resulted in pupal metamorphic lethality caused by tendon defects, matching the characteristics of human A-type lamin revealed by Emery-Dreifuss muscular dystrophy (EDMD). In tendon cells lacking lamin C activity, overall cell morphology was affected and organization of the spectraplakin family cytoskeletal protein Shortstop which is prominently expressed in tendon cells gradually disintegrated, notably around the nucleus and in a manner correlating well with the degradation of musculature. Furthermore, lamin C null mutants were efficiently rescued by restoring lamin C expression to shortstop-expressing cells, which include tendon cells but exclude skeletal muscle cells. Thus the critical function of A-type lamin C proteins in Drosophila musculature is to maintain proper function and morphology of tendon cells. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. BNL alternating gradient synchrotron with four helical magnets to minimize the losses of the polarized proton beam

    Directory of Open Access Journals (Sweden)

    N. Tsoupas

    2013-04-01

    Full Text Available 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

  1. Tuning the beam: a physics perspective on beam diagnostic instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Gulley, Mark S [Los Alamos National Laboratory

    2010-01-01

    In a nutshell, the role of a beam diagnostic measurement is to provide information needed to get a particle beam from Point A (injection point) to Point B (a target) in a useable condition, with 'useable' meaning the right energy and size and with acceptable losses. Specifications and performance requirements of diagnostics are based on the physics of the particle beam to be measured, with typical customers of beam parameter measurements being the accelerator operators and accelerator physicists. This tutorial will be a physics-oriented discussion of the interplay between tuning evolutions and the beam diagnostics systems that support the machine tune. This will include the differences between developing a tune and maintaining a tune, among other things. Practical longitudinal and transverse tuning issues and techniques from a variety of proton and electron machines will also be discussed.

  2. Beam diagnostics

    CERN Document Server

    Raich, U

    2008-01-01

    Most beam measurements are based on the electro-magnetic interaction of fields induced by the beam with their environment. Beam current transformers as well as beam position monitors are based on this principle. The signals induced in the sensors must be amplified and shaped before they are converted into numerical values. These values are further treated numerically in order to extract meaningful machine parameter measurements. The lecture introduces the architecture of an instrument and shows where in the treatment chain digital signal analysis can be introduced. Then the use of digital signal processing is presented using tune measurements, orbit and trajectory measurements as well as beam loss detection and longitudinal phase space tomography as examples. The hardware as well as the treatment algorithms and their implementation on Digital Signal Processors (DSPs) or in Field Programmable Gate Arrays (FPGAs) are presented.

  3. Merged-beams energy-loss technique for electron-ion excitation: Absolute total cross sections for O5+(2s→2p)

    International Nuclear Information System (INIS)

    Bell, E.W.; Guo, X.Q.; Forand, J.L.; Rinn, K.; Swenson, D.R.; Thompson, J.S.; Dunn, G.H.; Bannister, M.E.; Gregory, D.C.; Phaneuf, R.A.; Smith, A.C.H.; Mueller, A.; Timmer, C.A.; Wahlin, E.K.; DePaola, B.D.; Belic, D.S.

    1994-01-01

    A merged-beams electron-energy-loss technique is described, by which absolute cross sections can be measured for near-threshold electron-impact excitation of multipy charged ions. Results are reported here for absolute total electron-impact excitation cross sections for the O 5+ (2s→2p) transition from below threshold to 1.6 eV above threshold. The experimental data are in good agremeent with a seven-state close-coupling calculation throughout the energy range of the experiment. Results agree with calculations showing that more than 90% of the electrons causing excitation are ejected in the backward direction in the center-of-mass frame. This backscattering is shown in both quantum-mechanical and semiclassical calculations. Evidence is observed for high-lying metastable autoionizing states with a lifetime of approximately 0.9 μs which are made to ionize by electron impact

  4. Splitting of high power, cw proton beams

    Directory of Open Access Journals (Sweden)

    Alberto Facco

    2007-09-01

    Full Text Available A simple method for splitting a high power, continuous wave (cw proton beam in two or more branches with low losses has been developed in the framework of the EURISOL (European Isotope Separation On-Line Radioactive Ion Beam Facility design study. The aim of the system is to deliver up to 4 MW of H^{-} beam to the main radioactive ion beam production target, and up to 100 kW of proton beams to three more targets, simultaneously. A three-step method is used, which includes magnetic neutralization of a fraction of the main H^{-} beam, magnetic splitting of H^{-} and H^{0}, and stripping of H^{0} to H^{+}. The method allows slow raising and individual fine adjustment of the beam intensity in each branch.

  5. Beam-beam effects in the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Shiltsev, V.; Alexahin, Y.; Lebedev, V.; Lebrun, P.; Moore, R.S.; Sen, T.; Tollestrup, A.; Valishev, A.; Zhang, X.L.; /Fermilab

    2005-01-01

    The Tevatron in Collider Run II (2001-present) is operating with 6 times more bunches, many times higher beam intensities and luminosities than in Run I (1992-1995). Electromagnetic long-range and head-on interactions of high intensity proton and antiproton beams have been significant sources of beam loss and lifetime limitations. We present observations of the beam-beam phenomena in the Tevatron and results of relevant beam studies. We analyze the data and various methods employed in operations, predict the performance for planned luminosity upgrades, and discuss ways to improve it.

  6. Precision intercomparison of beam current monitors at CEBAF

    International Nuclear Information System (INIS)

    Kazimi, R.; Dunham, B.; Krafft, G.A.; Legg, R.; Liang, C.; Sinclair, C.; Mamosser, J.

    1995-01-01

    The CEBAF accelerator delivers a CW electron beam at fundamental 1497 MHz, with average beam current up to 200 μA. Accurate, stable nonintercepting beam current monitors are required for: setup/control, monitoring of beam current and beam losses for machine protection and personnel safety, and providing beam current information to experimental users. Fundamental frequency stainless steel RF cavities have been chosen for these beam current monitors. This paper reports on precision intercomparison between two such RF cavities, an Unser monitor, and two Faraday cups, all located in the injector area. At the low beam energy in the injector, it is straightforward to verify the high efficiency of the Faraday cups, and the Unser monitor included a wire through it to permit an absolute calibration. The cavity intensity monitors have proven capable of stable, high precision monitoring of the beam current

  7. Beam-induced quench test of LHC main quadrupole

    CERN Document Server

    Priebe, A; Dehning, B; Effinger, E; Emery, J; Holzer, E B; Kurfuerst, C; Nebot Del Busto, E; Nordt, A; Sapinski, M; Steckert, J; Verweij, A; Zamantzas, C

    2011-01-01

    Unexpected beam loss might lead to a transition of the accelerator superconducting magnet to a normal conducting state. The LHC beam loss monitoring (BLM) system is designed to abort the beam before the energy deposited in the magnet coils reach a quench-provoking level. In order to verify the threshold settings generated by simulation, a series of beam-induced quench tests at various beam energies has been performed. The beam losses are generated by means of an orbital bump peaked in one of main quadrupole magnets (MQ). The analysis includes not only BLM data but also the quench protection system (QPS) and cryogenics data. The measurements are compared to Geant4 simulations of energy deposition inside the coils and corresponding BLM signal outside the cryostat.

  8. Solution of the Fokker-Planck equation with mixing of angular harmonics by beam-beam charge exchange

    International Nuclear Information System (INIS)

    Mikkelsen, D.R.

    1989-09-01

    A method for solving the linear Fokker-Planck equation with anisotropic beam-beam charge exchange loss is presented. The 2-D equation is transformed to a system of coupled 1-D equations which are solved iteratively as independent equations. Although isotropic approximations to the beam-beam losses lead to inaccurate fast ion distributions, typically only a few angular harmonics are needed to include accurately the effect of the beam-beam charge exchange loss on the usual integrals of the fast ion distribution. Consequently, the algorithm converges very rapidly and is much more efficient than a 2-D finite difference method. A convenient recursion formula for the coupling coefficients is given and generalization of the method is discussed. 13 refs., 2 figs

  9. Benefits of group living include increased feeding efficiency and lower mass loss during desiccation in the social and inbreeding spider Stegodyphus dumicola.

    Directory of Open Access Journals (Sweden)

    Bram eVanthournout

    2016-02-01

    Full Text Available Group living carries a price: it inherently entails increased competition for resources and reproduction, and may also be associated with mating among relatives, which carries costs of inbreeding. Nonetheless, group living and sociality is found in many animals, and understanding the direct and indirect benefits of cooperation that override the inherent costs remains a challenge in evolutionary ecology. Individuals in groups may benefit from more efficient management of energy or water reserves, for example in the form of reduced water or heat loss from groups of animals huddling, or through reduced energy demands afforded by shared participation in tasks. We investigated the putative benefits of group living in the permanently social spider Stegodyphus dumicola by comparing the effect of group size on standard metabolic rate, lipid/protein content as a body condition measure, feeding efficiency, per capita web investment and weight/water loss and survival during desiccation. Because energetic expenditure is temperature sensitive, some assays were performed under varying temperature conditions. We found that feeding efficiency increased with group size, and the rate of weight loss was higher in solitary individuals than in animals in groups of various sizes during desiccation. Interestingly, this was not translated into differences in survival or in standard metabolic rate. We did not detect any group size effects for other parameters, and group size effects did not co-vary with experimental temperature in a predictive manner. Both feeding efficiency and mass loss during desiccation are relevant ecological factors as the former results in lowered predator exposure time, and the latter benefits social spiders which occupy arid, hot environments.

  10. 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

  11. RELAP5/MOD2. 5 analysis of the HFBR (High Flux Beam Reactor) for a loss of power and coolant accident

    Energy Technology Data Exchange (ETDEWEB)

    Slovik, G.C.; Rohatgi, U.S.; Jo, Jae.

    1990-05-01

    A set of postulated accidents were evaluated for the High Flux Beam Reactor (HFBR) at Brookhaven National Laboratory. A loss of power accident (LOPA) and a loss of coolant accident (LOCA) were analyzed. This work was performed in response to a DOE review that wanted to update the understanding of the thermal hydraulic behavior of the HFBR during these transients. These calculations were used to determine the margins to fuel damage at the 60 MW power level. The LOPA assumes all the backup power systems fail (although this event is highly unlikely). The reactor scrams, the depressurization valve opens, and the pumps coast down. The HFBR has down flow through the core during normal operation. To avoid fuel damage, the core normally goes through an extended period of forced down flow after a scram before natural circulation is allowed. During a LOPA, the core will go into flow reversal once the buoyancy forces are larger than the friction forces produced during the pump coast down. The flow will stagnate, reverse direction, and establish a buoyancy driven (natural circulation) flow around the core. Fuel damage would probably occur if the critical heat flux (CHF) limit is reached during the flow reversal event. The RELAP5/MOD2.5 code, with an option for heavy water, was used to model the HFBR and perform the LOPA calculation. The code was used to predict the time when the buoyancy forces overcome the friction forces and produce upward directed flow in the core. The Monde CHF correlation and experimental data taken for the HFBR during the design verification phase in 1963 were used to determine the fuel damage margin. 20 refs., 40 figs., 11 tabs.

  12. RELAP5/MOD2.5 analysis of the HFBR [High Flux Beam Reactor] for a loss of power and coolant accident

    International Nuclear Information System (INIS)

    Slovik, G.C.; Rohatgi, U.S.; Jo, Jae.

    1990-05-01

    A set of postulated accidents were evaluated for the High Flux Beam Reactor (HFBR) at Brookhaven National Laboratory. A loss of power accident (LOPA) and a loss of coolant accident (LOCA) were analyzed. This work was performed in response to a DOE review that wanted to update the understanding of the thermal hydraulic behavior of the HFBR during these transients. These calculations were used to determine the margins to fuel damage at the 60 MW power level. The LOPA assumes all the backup power systems fail (although this event is highly unlikely). The reactor scrams, the depressurization valve opens, and the pumps coast down. The HFBR has down flow through the core during normal operation. To avoid fuel damage, the core normally goes through an extended period of forced down flow after a scram before natural circulation is allowed. During a LOPA, the core will go into flow reversal once the buoyancy forces are larger than the friction forces produced during the pump coast down. The flow will stagnate, reverse direction, and establish a buoyancy driven (natural circulation) flow around the core. Fuel damage would probably occur if the critical heat flux (CHF) limit is reached during the flow reversal event. The RELAP5/MOD2.5 code, with an option for heavy water, was used to model the HFBR and perform the LOPA calculation. The code was used to predict the time when the buoyancy forces overcome the friction forces and produce upward directed flow in the core. The Monde CHF correlation and experimental data taken for the HFBR during the design verification phase in 1963 were used to determine the fuel damage margin. 20 refs., 40 figs., 11 tabs

  13. First years experience of LHC Beam Instrumentation

    CERN Document Server

    Jones, O R

    2011-01-01

    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. This paper will comment on all of these systems and on their contributions to the various stages of beam commissioning. It will include details on: the beam position system and its use for realtime global orbit feedback; the beam loss system and its role in machine protection; total and bunch by bunch intensity measurements; tune measurement and feedback; synchrotron light 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.

  14. Evaluation of diagnostic accuracy of conventional and digital periapical radiography, panoramic radiography, and cone-beam computed tomography in the assessment of alveolar bone loss.

    Science.gov (United States)

    Takeshita, Wilton Mitsunari; Vessoni Iwaki, Lilian Cristina; Da Silva, Mariliani Chicarelli; Tonin, Renata Hernandes

    2014-07-01

    To evaluate the diagnostic accuracy of different radiographic methods in the assessment of proximal alveolar bone loss (ABL). ABL, the distance between cement-enamel junction and alveolar bone crest, was measured in 70 mandibular human teeth - directly on the mandibles (control), using conventional periapical radiography with film holders (Rinn XCP and Han-Shin), digital periapical radiography with complementary metal-oxide semiconductor sensor, conventional panoramic, and cone-beam computed tomography (CBCT). Three programs were used to measure ABL on the images: Image tool 3.0 (University of Texas Health Sciences Center, San Antonio, Texas, USA), Kodak Imaging 6.1 (Kodak Dental Imaging 6.1, Carestream Health(®), Rochester, NY, USA), and i-CAT vision 1.6.20. Statistical analysis used ANOVA and Tukey's test at 5% significance level. The tomographic images showed the highest means, whereas the lowest were found for periapical with Han-Shin. Controls differed from periapical with Han-Shin (P periapical with Rinn XCP (P = 0.0066), periapical with Han-Shin (P periapical (P = 0.0027). Conventional periapicals with film holders differed from each other (P = 0.0007). Digital periapical differed from conventional periapical with Han-Shin (P = 0.0004). Conventional periapical with Han-Shin film holder was the only method that differed from the controls. CBCT had the closest means to the controls.

  15. 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

    Directory of Open Access Journals (Sweden)

    E. Mahner

    2004-10-01

    Full Text Available 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^{4} to 10^{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 setup, the results of the pressure rise measurements are presented, and the derived desorption yields are compared with data from other experiments.

  16. Optics of Electron Beam in the Recycler

    International Nuclear Information System (INIS)

    Burov, A.; Kroc, T.; Lebedev, V.; Nagaitsev, S.; Prost, L.; Pruss, S.; Shemyakin, A.; Sutherland, M.; Warner, A.; Kazakevich, G.; Tiunov, M.

    2006-01-01

    Electron cooling of 8.9 GeV/c antiprotons in the Recycler ring (Fermilab) requires high current and good quality of the DC electron beam. Electron trajectories of ∼0.2 A or higher DC electron beam have to be parallel in the cooling section, within ∼ 0.2 mrad, making the beam envelope cylindrical. These requirements yielded a specific scheme of the electron transport from a gun to the cooling section, with electrostatic acceleration and deceleration in the Pelletron. Recuperation of the DC beam limits beam losses at as tiny level as ∼0.001%, setting strict requirements on the return electron line to the Pelletron and a collector. To smooth the beam envelope in the cooling section, it has to be linear and known at the transport start. Also, strength of the relevant optic elements has to be measured with good accuracy. Beam-based optic measurements are being carried out and analysed to get this information. They include beam simulations in the Pelletron, differential optic (beam response) measurements and simulation, beam profile measurements with optical transition radiation, envelope measurements and analysis with orifice scrapers. Current results for the first half-year of commissioning are presented. Although electron cooling is already routinely used for pbar stacking, its efficiency is expected to be improved

  17. Hair Loss

    Science.gov (United States)

    ... conditions can cause hair loss, including: Hormonal changes. Hormonal changes and imbalances can cause temporary hair loss. This could be due to pregnancy, childbirth or the onset of menopause. Hormone levels are also affected by the thyroid ...

  18. Is a Picture Worth a Thousand Words? Few Evidence-Based Features of Dietary Interventions Included in Photo Diet Tracking Mobile Apps for Weight Loss.

    Science.gov (United States)

    Hales, Sarah; Dunn, Caroline; Wilcox, Sara; Turner-McGrievy, Gabrielle M

    2016-11-01

    Apps using digital photos to track dietary intake and provide feedback are common, but currently there has been no research examining what evidence-based strategies are included in these apps. A content analysis of mobile apps for photo diet tracking was conducted, including whether effective techniques for interventions promoting behavior change, including self-regulation, for healthy eating (HE) are targeted. An initial search of app stores yielded 34 apps (n = 8 Android and Apple; n = 11 Android; n = 15 Apple). One app was removed (unable to download), and other apps (n = 4) were unable to be rated (no longer available). Remaining apps (n = 29) were downloaded, reviewed, and coded by 2 independent reviewers to determine the number of known effective self-regulation and other behavior change techniques included. The raters met to compare their coding of the apps, calculate interrater agreement, resolve any discrepancies, and come to a consensus. Six apps (21%) did not utilize any of the behavior change techniques examined. Three apps (10%) provided feedback to users via crowdsourcing or collective feedback from other users and professionals, 7 apps (24%) used crowdsourcing or collective feedback, 1 app (3%) used professionals, and 18 apps (62%) did not provide any dietary feedback to users. Few photo diet-tracking apps include evidence-based strategies to improve dietary intake. Use of photos to self-monitor dietary intake and receive feedback has the potential to reduce user burden for self-monitoring, yet photo diet tracking apps need to incorporate known effective behavior strategies for HE, including self-regulation. © 2016 Diabetes Technology Society.

  19. Evaluation of diagnostic accuracy of conventional and digital periapical radiography, panoramic radiography, and cone-beam computed tomography in the assessment of alveolar bone loss

    Directory of Open Access Journals (Sweden)

    Wilton Mitsunari Takeshita

    2014-01-01

    Full Text Available Background: To evaluate the diagnostic accuracy of different radiographic methods in the assessment of proximal alveolar bone loss (ABL. Materials and Methods: ABL, the distance between cement-enamel junction and alveolar bone crest, was measured in 70 mandibular human teeth - directly on the mandibles (control, using conventional periapical radiography with film holders (Rinn XCP and Han-Shin, digital periapical radiography with complementary metal-oxide semiconductor sensor, conventional panoramic, and cone-beam computed tomography (CBCT. Three programs were used to measure ABL on the images: Image tool 3.0 (University of Texas Health Sciences Center, San Antonio, Texas, USA, Kodak Imaging 6.1 (Kodak Dental Imaging 6.1, Carestream Health ® , Rochester, NY, USA, and i-CAT vision 1.6.20. Statistical analysis used ANOVA and Tukey′s test at 5% significance level. Results: The tomographic images showed the highest means, whereas the lowest were found for periapical with Han-Shin. Controls differed from periapical with Han-Shin (P < 0.0001. CBCT differed from panoramic (P = 0.0130, periapical with Rinn XCP (P = 0.0066, periapical with Han-Shin (P < 0.0001, and digital periapical (P = 0.0027. Conventional periapicals with film holders differed from each other (P = 0.0007. Digital periapical differed from conventional periapical with Han-Shin (P = 0.0004. Conclusions: Conventional periapical with Han-Shin film holder was the only method that differed from the controls. CBCT had the closest means to the controls.

  20. LHC Beam Instrumentation: Beam Position and Intensity Measurements (1/3)

    CERN Multimedia

    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.

  1. Molecular beams

    International Nuclear Information System (INIS)

    Ramsey, N.F.

    1985-01-01

    This book is a timeless and rather complete theoretical and experimental treatment of electric and magnetic resonance molecular-beam experiments for studying the radio frequency spectra of atoms and molecules. The theory of interactions of the nucleus with atomic and molecular fields is extensively presented. Measurements of atomic and nuclear magnetic moments, electric multipole moments, and atomic fine and hyperfine structure are detailed. Useful but somewhat outdated chapters on gas kinetics, molecular beam design, and experimental techniques are also included

  2. Reconstruction of negative hydrogen ion beam properties from beamline diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Ruf, Benjamin

    2014-09-25

    (BES). BES measures the beam divergence and beam power losses from heavy-particle collisions by evaluating the spectrum of the Balmer H{sub α} light of the beam. The light is emitted since beam particles are excited by collisions with the hydrogen background gas. For ITER, BES will be the main beam diagnostic tool for beam quality measurements. The main results are, that first of all, the evaluation of the beam divergence from a BES spectrum was improved with the parametrisation method. Furthermore it turned out that the evaluation of stripping losses and beam inhomogeneity in large negative hydrogen ion sources cannot be performed by backward calculations from a BES spectra, i.e. by the analysis of the spectra. This means forward modeling has to be done, which does also include the simulation of other beam diagnostic tools, like the power density profile measured by the calorimeter. Combining all beam diagnostic tools and reconstructing their outcome with a BBC-NI Advanced simulation, gives the possibility to determine the beam parameters by extracting them from the BBC-NI code protocols. This requires a lot of effort and is not well suited for a routine analysis. For ITER this means that solely a BES system for the determination of the beam parameters (i.e. stripping losses and beam inhomogeneity), as it is presently foreseen, is not sufficient. Several beam diagnostic tools, e.g. the calorimeter which can determine the power density profile of the beam, and a code like BBC-NI are necessary. Additionally for the application of BBC-NI Advanced, a beam optic code is needed, which is able to generate a realistic electric field map in the extraction system. Such an optic code is not available so far.

  3. Measuring, calculating and estimating PEP's parasitic mode loss parameters

    International Nuclear Information System (INIS)

    Weaver, J.N.

    1981-01-01

    This note discusses various ways the parasitic mode losses from a bunched beam to a vacuum chamber can be measured, calculated or estimated. A listing of the parameter, k, for the various PEP ring components is included. A number of formulas for calculating multiple and single pass losses are discussed and evaluated for several cases. 25 refs., 1 fig., 1 tab

  4. Beam transport

    International Nuclear Information System (INIS)

    1988-01-01

    Considerable experience has now been gained with the various beam transport lines, and a number of minor changes have been made to improve the ease of operation. These include: replacement of certain little-used slits by profile monitors (harps or scanners); relocation of steering magnets, closer to diagnostic harps or profile scanners; installation of a scanner inside the isocentric neutron therapy system; and conversion of a 2-doublet quadrupole telescope (on the neutron therapy beamline) to a 2-triplet telescope. The beam-swinger project has been delayed by very late delivery of the magnet iron to the manufacturer, but is now progressing smoothly. The K=600 spectrometer magnets have now been delivered and are being assembled for field mapping. The x,y-table with its associated mapping equipment is complete, together with the driver software. One of the experimental areas has been dedicated to the production of collimated neutron beams and has been equipped with a bending magnet and beam dump, together with steel collimators fixed at 4 degrees intervals from 0 degrees to 16 degrees. Changes to the target cooling and shielding system for isotope production have led to a request for much smaller beam spot sizes on target, and preparations have been made for rearrangement of the isotope beamline to permit installation of quadrupole triplets on the three beamlines after the switching magnet. A practical system of quadrupoles for matching beam properties to the spectrometer has been designed. 6 figs

  5. Beam transport design for a recirculating-linac FEL driver

    International Nuclear Information System (INIS)

    Neuffer, D.; Douglas, D.; Li, Z.; Cornacchia, M.; Garren, A.

    1996-01-01

    The beam transport system for the CEBAF Industrial FEL includes a two-pass transport of the beam with acceleration from injector to wiggler, followed by energy recovery transport from wiggler to dump. From that context, the authors discuss the general problem of multi-pass energy-recovery beam transport for FELs. Tunable, nearly-isochronous, large-momentum-acceptance transport systems are required. The entire transport must preserve beam quality, particularly in the acceleration transport to the wiggler, and have low losses throughout the entire system. Various possible designs are presented, and results of dynamic analyses are discussed

  6. Thermally induced diffraction losses for a Gaussian pump beam and optimization of the mode-to-pump ratio in an end-pumped Nd:GdVO4 laser

    International Nuclear Information System (INIS)

    Wang, Y T; Li, W J; Pan, L L; Yu, J T; Zhang, R H

    2013-01-01

    The analytical model of thermally induced diffraction losses for a Gaussian pump beam are derived as functions of the mode-to-pump ratio and pump power in end-pumped Nd-doped lasers considering the energy transfer upconversion effects. The mode-to-pump ratio is optimized based on it. The results show that the optimum mode-to-pump ratio with the thermally induced diffraction losses is less than 0.65, and it is less than the results in which the thermally induced diffraction losses are neglected. The theoretical model is applied to a diode-end-pumped Nd:GdVO 4 laser operating at 1342 nm, and the theoretical calculations are in good agreement with the experimental results. (paper)

  7. Electron beam control for barely separated beams

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, David R.; Ament, Lucas J. P.

    2017-04-18

    A method for achieving independent control of multiple beams in close proximity to one another, such as in a multi-pass accelerator where coaxial beams are at different energies, but moving on a common axis, and need to be split into spatially separated beams for efficient recirculation transport. The method for independent control includes placing a magnet arrangement in the path of the barely separated beams with the magnet arrangement including at least two multipole magnets spaced closely together and having a multipole distribution including at least one odd multipole and one even multipole. The magnetic fields are then tuned to cancel out for a first of the barely separated beams to allow independent control of the second beam with common magnets. The magnetic fields may be tuned to cancel out either the dipole component or tuned to cancel out the quadrupole component in order to independently control the separate beams.

  8. Electron beam solenoid reactor concept

    International Nuclear Information System (INIS)

    Bailey, V.; Benford, J.; Cooper, R.; Dakin, D.; Ecker, B.; Lopez, O.; Putman, S.; Young, T.S.T.

    1977-01-01

    The electron Beam Heated Solenoid (EBHS) reactor is a linear magnetically confined fusion device in which the bulk or all of the heating is provided by a relativistic electron beam (REB). The high efficiency and established technology of the REB generator and the ability to vary the coupling length make this heating technique compatible with several radial and axial enery loss reduction options including multiple-mirrors, electrostatic and gas end-plug techniques. This paper addresses several of the fundamental technical issues and provides a current evaluation of the concept. The enhanced confinement of the high energy plasma ions due to nonadiabatic scattering in the multiple mirror geometry indicates the possibility of reactors of the 150 to 300 meter length operating at temperatures > 10 keV. A 275 meter EBHS reactor with a plasma Q of 11.3 requiring 33 MJ of beam eneergy is presented

  9. Electron beam damage in oxides: a review.

    Science.gov (United States)

    Jiang, Nan

    2016-01-01

    This review summarizes a variety of beam damage phenomena relating to oxides in (scanning) transmission electron microscopes, and underlines the shortcomings of currently popular mechanisms. These phenomena include mass loss, valence state reduction, phase decomposition, precipitation, gas bubble formation, phase transformation, amorphization and crystallization. Moreover, beam damage is also dependent on specimen thickness, specimen orientation, beam voltage, beam current density and beam size. This article incorporates all of these damage phenomena and experimental dependences into a general description, interpreted by a unified mechanism of damage by induced electric field. The induced electric field is produced by positive charges, which are generated from excitation and ionization. The distribution of the induced electric fields inside a specimen is beam-illumination- and specimen-shape- dependent, and associated with the experimental dependence of beam damage. Broadly speaking, the mechanism operates differently in two types of material. In type I, damage increases the resistivity of the irradiated materials, and is thus divergent, resulting in phase separation. In type II, damage reduces the resistivity of the irradiated materials, and is thus convergent, resulting in phase transformation. Damage by this mechanism is dependent on electron-beam current density. The two experimental thresholds are current density and irradiation time. The mechanism comes into effect when these thresholds are exceeded, below which the conventional mechanisms of knock-on and radiolysis still dominate.

  10. Assessing electron beam sensitivity for SrTiO{sub 3} and La{sub 0.7}Sr{sub 0.3}MnO{sub 3} using electron energy loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nord, Magnus, E-mail: magnunor@gmail.com [Department of Physics, NTNU, Trondheim (Norway); Vullum, Per Erik [Department of Physics, NTNU, Trondheim (Norway); Materials and Chemistry, SINTEF, Trondheim (Norway); Hallsteinsen, Ingrid; Tybell, Thomas [Department of Electronics and Telecommunications, NTNU, Trondheim (Norway); Holmestad, Randi [Department of Physics, NTNU, Trondheim (Norway)

    2016-10-15

    Thresholds for beam damage have been assessed for La{sub 0.7}Sr{sub 0.3}MnO{sub 3} and SrTiO{sub 3} as a function of electron probe current and exposure time at 80 and 200 kV 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 200 kV acceleration voltage, damage in SrTiO{sub 3} 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 SrTiO{sub 3} at 80 kV acceleration voltage, independent of probe current and exposure time. In La{sub 0.7}Sr{sub 0.3}MnO{sub 3}, beam damage was observed at both 80 and 200 kV 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. - Highlights: • We studied the effects of a TEM electron beam on a perovskite heterostructure. • Using an improved ELNES quantification method, subtle changes could be observed. • On LSMO changes were observed in the ELNES, but none in the STEM-HAADF. • For STO changes were observed in both ELNES and STEM-HAADF. • This shows beam damage can be misinterpreted as material properties.

  11. Terascale Beam-Beam Simulations for Tevatron, RHIC and LHC

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, J.

    2005-05-16

    In this paper, we report on recent advances in terascale simulations of the beam-beam interaction in Tevatron, RHIC and LHC.Computational methods for self consistent calculation of beam-beam forces are reviewed. New method for solving the two-dimensional Poisson equation with open boundary conditions is proposed and tested. This new spectral-finite difference method is a factor of four faster than the widely used FFT based Green function method for beam-beam interaction on axis. We also present applications to the study of antiproton losses during the injection stage at Tevatron, to the study of multiple bunch coherent beam-beam modes at RHIC, and to the study of beam-beam driven emittance growth at LHC.

  12. Terascale Beam-Beam Simulations for Tevatron, RHIC and LHC

    International Nuclear Information System (INIS)

    Qiang, J.

    2005-01-01

    In this paper, we report on recent advances in terascale simulations of the beam-beam interaction in Tevatron, RHIC and LHC.Computational methods for self consistent calculation of beam-beam forces are reviewed. New method for solving the two-dimensional Poisson equation with open boundary conditions is proposed and tested. This new spectral-finite difference method is a factor of four faster than the widely used FFT based Green function method for beam-beam interaction on axis. We also present applications to the study of antiproton losses during the injection stage at Tevatron, to the study of multiple bunch coherent beam-beam modes at RHIC, and to the study of beam-beam driven emittance growth at LHC

  13. Low current beam techniques

    Energy Technology Data Exchange (ETDEWEB)

    Saint, A.; Laird, J.S.; Bardos, R.A.; Legge, G.J.F. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Nishijima, T.; Sekiguchi, H. [Electrotechnical Laboratory, Tsukuba (Japan).

    1993-12-31

    Since the development of Scanning Transmission Microscopy (STIM) imaging in 1983 many low current beam techniques have been developed for the scanning (ion) microprobe. These include STIM tomography, Ion Beam Induced Current, Ion Beam Micromachining and Microlithography and Ionoluminense. Most of these techniques utilise beam currents of 10{sup -15} A down to single ions controlled by beam switching techniques This paper will discuss some of the low beam current techniques mentioned above, and indicate, some of their recent applications at MARC. A new STIM technique will be introduced that can be used to obtain Z-contrast with STIM resolution. 4 refs., 3 figs.

  14. Beam Techniques - Beam Control and Manipulation

    Energy Technology Data Exchange (ETDEWEB)

    Minty, Michiko G

    2003-04-24

    We describe commonly used strategies for the control of charged particle beams and the manipulation of their properties. Emphasis is placed on relativistic beams in linear accelerators and storage rings. After a brief review of linear optics, we discuss basic and advanced beam control techniques, such as transverse and longitudinal lattice diagnostics, matching, orbit correction and steering, beam-based alignment, and linac emittance preservation. A variety of methods for the manipulation of particle beam properties are also presented, for instance, bunch length and energy compression, bunch rotation, changes to the damping partition number, and beam collimation. The different procedures are illustrated by examples from various accelerators. Special topics include injection and extraction methods, beam cooling, spin transport and polarization.

  15. Beam scanning system

    International Nuclear Information System (INIS)

    Enge, H.A.

    1977-01-01

    A system for deflecting a beam of particles having different momenta, preferably through a 90 0 angle, so as to cause the beam to impinge upon a moving target and to scan across the target is described. The system includes a means responsive to a beam from a suitable source for causing the beam to periodically scan in a scanning plane and further means for deflecting the periodically scanned beam through the desired angle in a deflection plane so that the deflected beam impinges on the target. Means are included in the system for reducing the momentum dispersion at the target in both the deflection and the scanning planes and for spatially focussing the beam so as to produce a desired beam diameter at the target

  16. Ion-chamber-based loss monitor system for the Los Alamos Meson Physics Facility

    International Nuclear Information System (INIS)

    Plum, M.A.; Brown, D.; Browman, A.; Macek, R.J.

    1995-01-01

    A new loss monitor system has been designed and installed at the Los Alamos Meson Physics Facility (LAMPF). The detectors are ion chambers filled with N 2 gas. The electronics modules have a threshold range of 1:100, and they can resolve changes in beam loss of about 2% of the threshold settings. They can generate a trip signal in 2 μs if the beam loss is large enough; if the response time of the Fast Protect System is included the beam will be shut off in about 37 μs

  17. Beam dynamics activities at the Thomas Jefferson National Accelerator Facility (Jefferson Lab)

    International Nuclear Information System (INIS)

    The Thomas Jefferson National Accelerator Facility (Jefferson Lab) has been funded by the US Navy to build an infra-red FEL driven by an energy-recovering compact SRF-based linear accelerator. The machine is to produce a 1 kW IR photon beam. The Jefferson Lab Accelerator Division is presently engaged in detailed design and beam dynamics studies for the driver accelerator. Principle beam dynamics and beam transport considerations include: (1) generation and transport of a high-quality, high-current, space-charge dominated beam; (2) the impact of coherent synchrotron radiation (CSR) during beam recirculation transport; (3) low-loss transport of a large momentum spread, high-current beam; (4) beam break up (BBU) instabilities in the recirculating accelerator; (5) impedance policing of transport system components; and (6) RF drive system control during energy recovery and FEL operation

  18. Coherent instabilities of a relativistic bunched beam

    International Nuclear Information System (INIS)

    Chao, A.W.

    1982-06-01

    A charge-particle beam contained in an accelerator vacuum chamber interacts electromagnetically with its environment to create a wake field. This field than acts back on the beam, perturbing the particle motion. If the beam intensity is high enough, this beam-environment interaction may lead to an instability and to subsequent beam loss. The beam and its environment form a dynamical system, and it is this system that will be studied. 84 references

  19. Coherent instabilities of a relativistic bunched beam

    Energy Technology Data Exchange (ETDEWEB)

    Chao, A.W.

    1982-06-01

    A charge-particle beam contained in an accelerator vacuum chamber interacts electromagnetically with its environment to create a wake field. This field than acts back on the beam, perturbing the particle motion. If the beam intensity is high enough, this beam-environment interaction may lead to an instability and to subsequent beam loss. The beam and its environment form a dynamical system, and it is this system that will be studied. 84 references.

  20. 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.

  1. BEAM HALO FORMATION IN HIGH-INTENSITY BEAMS.

    Energy Technology Data Exchange (ETDEWEB)

    FEDOTOV, A.V.

    2005-03-18

    Studies of beam halo became unavoidable feature of high-intensity machines where uncontrolled beam loss should be kept to extremely small level. For a well controlled stable beam such a loss is typically associated with the low density halo surrounding beam core. In order to minimize uncontrolled beam loss or improve performance of an accelerator, it is very important to understand what are the sources of halo formation in a specific machine of interest. The dominant mechanisms are, in fact, different in linear accelerators, circular machines or Energy Recovering Linacs (ERL). In this paper, we summarize basic mechanisms of halo formation in high-intensity beams and discuss their application to various types of accelerators of interest, such as linacs, rings and ERL.

  2. Beam-beam simulation of Möbius-modified CESR

    Science.gov (United States)

    Talman, R.; Malitsky, N.; Koyama, T.

    1997-05-01

    Colliding beam experiments at CESR with beams made round by running on the coupling resonance have been performed,(E. Young et al.), abstract, this conference and runs are planned with the beams made round by Möbius modification.(R. Talman, Phys. Rev. Lett. 74), 1590, (1995) Performance in these configurations has been simulated using TEAPOT++ tracking, map generation, stochastic, and beam-beam modules within the Unified Accelerator Libraries(N. Malitsky et al.), abstract, this conference The true CESR lattice including sextupoles and element apertures is used. Outputs from the calculation include beam profile modification, tune optimization, maximum luminosity, and (with extrapolation) beam lifetimes.

  3. Beam dynamics design studies of a superconducting radioactive ion beam postaccelerator

    Directory of Open Access Journals (Sweden)

    M. A. Fraser

    2011-02-01

    Full Text Available The HIE-ISOLDE project at CERN proposes a superconducting upgrade to increase the energy range and quality of the radioactive ion beams produced at ISOLDE, which are currently postaccelerated by the normal conducting radioactive ion beam experiment linac. The specification and design choices for the HIE-ISOLDE linac are outlined along with a comprehensive beam dynamics study undertaken to understand and mitigate the sources of beam emittance dilution. The dominant cause of transverse emittance growth was attributed to the coupling between the transverse and longitudinal motions through the phase dependence of the rf defocusing force in the accelerating cavities. A parametric resonance induced by the coupling was observed and its excitation surveyed as a function of transverse phase advance using numerical simulations and analytic models to understand and avoid the regions of transverse beam instability. Other sources of emittance growth were studied and where necessary ameliorated, including the beam steering force in the quarter-wave resonator and the asymmetry of the rf defocusing forces in the solenoid focusing channel. A racetrack shaped beam port aperture was shown to improve the symmetry of the fields in the high-β quarter-wave resonator and reduce the loss of acceptance under the offset used to compensate the steering force. The methods used to compensate the beam steering are described and an optimization routine written to minimize the steering effect when all cavities of a given family are offset by the same amount, taking into account the different velocity profiles across the range of mass-to-charge states accepted. The assumptions made in the routine were shown to be adequate and the results well correlated with the beam quality simulated in multiparticle beam dynamics simulations. The specification of the design tolerances is outlined based on studies of the sensitivity of the beam to misalignment and errors, with particular

  4. Cross sections of electron loss and capture for beams of O+ in water vapor from the energy range of 0,2 to 1,2 MeV

    International Nuclear Information System (INIS)

    Oliveira, Vitor Jesus de

    2015-01-01

    The study of the interactions between atoms and molecules is important for the knowledge of the cross sections of the processes that contribute to the deposition of energy by charged particle beams used in radiotherapy planning and transport particle simulation codes. Heavy ions, such as oxygen, induce many cellular and molecular damages in human cells.as a result of interaction between the projectile and atoms and molecules. The use of proton and carbon as the projectile interacting with water molecules is well characterized, however there are few studies with oxygen ions. In this work we are interested in the study of electron loss (projectile ionization) and electron capture with charge state 1+. The Pelletron accelerator of 1.7 MeV from the Federal University of Rio de Janeiro housed in the Atomic and Molecular collisions Laboratory (LACAM) has been used, which can accelerate atomic and molecular ions up to speeds of the order of hundredths of light speed, and consists of the source of negative ions, the Wien filter, the accelerator itself and the magnet load selector. The detection device used to evaluate the processes of interaction (capture and loss) between the beam of the O + and the water molecule is a Microchannel Plate (MCP) at the position sensitive anode. The collisions of O + beans are being studied in the range of 0.2 to 1.2 MeV with water vapor (Z = 10). Were obtained the respective absolute cross sections for electron loss and electron capture and compared with the cross sections of the molecule methane (CH4 → Z = 10), the isoelectronic water molecule. The experimental results show an agreement between the measurements with water and methane. Comparisons were made with results of theoretical models for electron loss using the 'Free Collision Model' and for capture the Bohr and Lindhard model. The theoretical results for electron loss show an agreement of experimental data with the model used. The model of Bohr and Lindhard describes

  5. Evaluation of diagnostic accuracy of conventional and digital periapical radiography, panoramic radiography, and cone-beam computed tomography in the assessment of alveolar bone loss

    OpenAIRE

    Wilton Mitsunari Takeshita; Lilian Cristina Vessoni Iwaki; Mariliani Chicarelli Da Silva; Renata Hernandes Tonin

    2014-01-01

    Background: To evaluate the diagnostic accuracy of different radiographic methods in the assessment of proximal alveolar bone loss (ABL). Materials and Methods: ABL, the distance between cement-enamel junction and alveolar bone crest, was measured in 70 mandibular human teeth - directly on the mandibles (control), using conventional periapical radiography with film holders (Rinn XCP and Han-Shin), digital periapical radiography with complementary metal-oxide semiconductor sensor, conventional...

  6. Time dependent formulation of the energy loss by an accelerated intense electron beam just emitted by the cathode of RF-FEL photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Salah, Wa' el [Physics Department, Hashemite University, Zarqa 13115 (Jordan)]. E-mail: wael_salahh@hotmail.com; Coacolo, J.-L. [Institut de Physique Nucleaire d' Orsay, 91406 Orsay Cedex (France); Hallak, A.B. [Physics Department, Hashemite University, Zarqa 13115 (Jordan); Al-Obaid, M. [Physics Department, Hashemite University, Zarqa 13115 (Jordan)

    2006-08-01

    The energy loss by an accelerated electron bunch of a conical shape propagating in the laser-driven RF-photoinjector is expressed in terms of an expansion of the vector and scalar potentials into a series of eigenfunctions of the empty unit 'pill-box' cavity. A versatile and simple analytical formula which can be easily applied to a bunch of any shape is obtained.

  7. Cyclotrons for high-intensity beams

    CERN Document Server

    Seidel, Mike

    2013-01-01

    This paper reviews the important physical and technological aspects of cyclotrons for the acceleration of high-intensity beams. Special emphasis is given to the discussion of beam loss mechanisms and extraction schemes.

  8. Beam-limiting and radiation-limiting interlocks

    International Nuclear Information System (INIS)

    Macek, R.J.

    1996-01-01

    This paper reviews several aspects of beam-limiting and radiation- limiting interlocks used for personnel protection at high-intensity accelerators. It is based heavily on the experience at the Los Alamos Neutron Science Center (LANSCE) where instrumentation-based protection is used extensively. Topics include the need for ''active'' protection systems, system requirements, design criteria, and means of achieving and assessing acceptable reliability. The experience with several specific devices (ion chamber-based beam loss interlock, beam current limiter interlock, and neutron radiation interlock) designed and/or deployed to these requirements and criteria is evaluated

  9. Beam-limiting and radiation-limiting interlocks

    Energy Technology Data Exchange (ETDEWEB)

    Macek, R.J.

    1996-04-01

    This paper reviews several aspects of beam-limiting and radiation- limiting interlocks used for personnel protection at high-intensity accelerators. It is based heavily on the experience at the Los Alamos Neutron Science Center (LANSCE) where instrumentation-based protection is used extensively. Topics include the need for ``active`` protection systems, system requirements, design criteria, and means of achieving and assessing acceptable reliability. The experience with several specific devices (ion chamber-based beam loss interlock, beam current limiter interlock, and neutron radiation interlock) designed and/or deployed to these requirements and criteria is evaluated.

  10. Organic-Carbon Sequestration in Soil/Sediment of the Mississippi River Deltaic Plain - Data; Landscape Distribution, Storage, and Inventory; Accumulation Rates; and Recent Loss, Including a Post-Katrina Preliminary Analysis (Chapter B)

    Science.gov (United States)

    Markewich, Helaine W.; Buell, Gary R.; Britsch, Louis D.; McGeehin, John P.; Robbins, John A.; Wrenn, John H.; Dillon, Douglas L.; Fries, Terry L.; Morehead, Nancy R.

    2007-01-01

    Soil/sediment of the Mississippi River deltaic plain (MRDP) in southeastern Louisiana is rich in organic carbon (OC). The MRDP contains about 2 percent of all OC in the surface meter of soil/sediment in the Mississippi River Basin (MRB). Environments within the MRDP differ in soil/sediment organic carbon (SOC) accumulation rate, storage, and inventory. The focus of this study was twofold: (1) develop a database for OC and bulk density for MRDP soil/sediment; and (2) estimate SOC storage, inventory, and accumulation rates for the dominant environments (brackish, intermediate, and fresh marsh; natural levee; distributary; backswamp; and swamp) in the MRDP. Comparative studies were conducted to determine which field and laboratory methods result in the most accurate and reproducible bulk-density values for each marsh environment. Sampling methods included push-core, vibracore, peat borer, and Hargis1 sampler. Bulk-density data for cores taken by the 'short push-core method' proved to be more internally consistent than data for samples collected by other methods. Laboratory methods to estimate OC concentration and inorganic-constituent concentration included mass spectrometry, coulometry, and loss-on-ignition. For the sampled MRDP environments, these methods were comparable. SOC storage was calculated for each core with adequate OC and bulk-density data. SOC inventory was calculated using core-specific data from this study and available published and unpublished pedon data linked to SSURGO2 map units. Sample age was estimated using isotopic cesium (137Cs), lead (210Pb), and carbon (14C), elemental Pb, palynomorphs, other stratigraphic markers, and written history. SOC accumulation rates were estimated for each core with adequate age data. Cesium-137 profiles for marsh soil/sediment are the least ambiguous. Levee and distributary 137Cs profiles show the effects of intermittent allochthonous input and/or sediment resuspension. Cesium-137 and 210Pb data gave the most

  11. Enhancement of the output power of terahertz folded waveguide oscillator by two parallel electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ke, E-mail: like.3714@163.com; Cao, Miaomiao, E-mail: mona486@yeah.net [Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100190 (China); Liu, Wenxin, E-mail: lwenxin@mail.ie.ac.cn; Wang, Yong, E-mail: wangyong3845@sina.com [Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190 (China); Liao, Suying, E-mail: suying-liao@163.com [Air Force Airborne Academy, Guilin, Guangxi 541003 (China)

    2015-11-15

    A novel two-beam folded waveguide (FW) oscillator is presented for the purpose of gaining higher power with a small-size circuit compared with the normal FW oscillator. The high-frequency characteristics of the two-beam FW, including dispersion and interaction impedance, were investigated by the numerical simulation and compared with the one-beam FW. The radio-frequency loss of the two-beam FW was also analyzed. A 3-D particle-in-cell code CHIPIC was applied to analyze and optimize the performance of a G-band two-beam FW oscillator. The influences of the distance between the two beam tunnels, beam voltage, the number of periods, magnetic field, radius of beam tunnel, and the packing ratio on the circuit performance are investigated in detail. Compared with a one-beam circuit, a larger output power of the two-beam circuit with the same beam power was observed by the simulation. Moreover, the start-oscillation current of two-beam circuit is much lower than the one-beam circuit with better performance. It will favor the miniaturized design of the high-power terahertz oscillator.

  12. Study of beam-beam long range compensation with octupoles

    CERN Document Server

    AUTHOR|(CDS)2068329; Pieloni, Tatiana; Buffat, Xavier; Tambasco, Claudia

    2017-01-01

    Long range beam-beam effects are responsible for particle losses and define fundamental operational parameters of colliders (i.e. crossing angles, intensities, emittances, ${\\beta}$${^∗}$). In this study we propose octuple magnets as a possible scheme to efficiently compensate long-range beam-beam interactions with a global correction scheme. The impact and improvements on the dynamic aperture of colliding beams together with estimates of the luminosity potentials are dis- cussed for the HL-LHC upgrade and extrapolations made for the FCC project.

  13. Hidden loss

    DEFF Research Database (Denmark)

    Kieffer-Kristensen, Rikke; Johansen, Karen Lise Gaardsvig

    2013-01-01

    finding indicates that the children experienced numerous losses, many of which were often suppressed or neglected by the children to protect the ill parents. CONCLUSIONS: The findings indicated that the children seemed to make a special effort to hide their feelings of loss and grief in order to protect...... the ill parent. These findings contribute to a deeper understanding of the traumatic process of parental ABI that some children experience and emphasize the importance of family-centred interventions that include the children....

  14. Limitations due to strong head-on beam-beam interactions (MD 1434)

    CERN Document Server

    Buffat, Xavier; Iadarola, Giovanni; Papadopoulou, Parthena Stefania; Papaphilippou, Yannis; Pellegrini, Dario; Pojer, Mirko; Crockford, Guy; Salvachua Ferrando, Belen Maria; Trad, Georges; Barranco Garcia, Javier; Pieloni, Tatiana; Tambasco, Claudia; CERN. Geneva. ATS Department

    2017-01-01

    The results of an experiment aiming at probing the limitations due to strong head on beam-beam interactions are reported. It is shown that the loss rates significantly increase when moving the working point up and down the diagonal, possibly due to effects of the 10th and/or 14th order resonances. Those limitations are tighter for bunches with larger beam-beam parameters, a maximum total beam-beam tune shift just below 0.02 could be reached.

  15. Coherent beam-beam effects

    International Nuclear Information System (INIS)

    Chao, A.W.

    1992-01-01

    There are two physical pictures that describe the beam-beam interaction in a storage ring collider: The weak-strong and the strong-strong pictures. Both pictures play a role in determining the beam-beam behavior. This review addresses only the strong-strong picture. The corresponding beam dynamical effects are referred to as the coherent beam-beam effects. Some basic knowledge of the weak-strong picture is assumed. To be specific, two beams of opposite charges are considered. (orig.)

  16. Electron beams in radiation therapy

    International Nuclear Information System (INIS)

    Bruinvis, I.A.D.

    1987-01-01

    Clinical electron beams in interaction with beam flattening and collimating devices are studied, in order to obtain the means for adequate electron therapy. A treatment planning method for arbitrary field shapes is developed that takes the properties of the collimated electron beams into account. An electron multiple-scattering model is extended to incorporate a model for the loss of electrons with depth, in order to improve electron beam dose planning. A study of ionisation measurements in two different phantom materials yields correction factors for electron beam dosimetry. (Auth.)

  17. OI Issues: Hearing Loss

    Science.gov (United States)

    ... loss can occur at any age, including childhood. Conductive Hearing Loss : Usually results from a physical problem in the ... This type of test can determine if the hearing loss is conductive or sensorineural. Adults who have an identified hearing ...

  18. Superresolution beams

    CSIR Research Space (South Africa)

    Ngcobo, S

    2011-11-01

    Full Text Available zones capable of introducing a phase shift of zero or p on the alternately out of phase rings of the TEMp0 beams into a unified phase and then focusing the rectified beam to generate a high resolution beam which has a Gaussian beam intensity distribution...

  19. TRACK The New Beam Dynamics Code

    CERN Document Server

    Mustapha, Brahim; Ostroumov, Peter; Schnirman-Lessner, Eliane

    2005-01-01

    The new ray-tracing code TRACK was developed* to fulfill the special requirements of the RIA accelerator systems. The RIA lattice includes an ECR ion source, a LEBT containing a MHB and a RFQ followed by three SC linac sections separated by two stripping stations with appropriate magnetic transport systems. No available beam dynamics code meet all the necessary requirements for an end-to-end simulation of the RIA driver linac. The latest version of TRACK was used for end-to-end simulations of the RIA driver including errors and beam loss analysis.** In addition to the standard capabilities, the code includes the following new features: i) multiple charge states ii) realistic stripper model; ii) static and dynamic errors iii) automatic steering to correct for misalignments iv) detailed beam-loss analysis; v) parallel computing to perform large scale simulations. Although primarily developed for simulations of the RIA machine, TRACK is a general beam dynamics code. Currently it is being used for the design and ...

  20. High intensity proton beam transportation through fringe field of 70 MeV compact cyclotron to beam line targets

    Science.gov (United States)

    Zhang, Xu; Li, Ming; Wei, Sumin; Xing, Jiansheng; Hu, Yueming; Johnson, Richard R.; Piazza, Leandro; Ryjkov, Vladimir

    2016-06-01

    From the stripping points, the high intensity proton beam of a compact cyclotron travels through the fringe field area of the machine to the combination magnet. Starting from there the beams with various energy is transferred to the switching magnet for distribution to the beam line targets. In the design of the extraction and transport system for the compact proton cyclotron facilities, such as the 70 MeV in France and the 100 MeV in China, the space charge effect as the beam crosses the fringe field has not been previously considered; neither has the impact on transverse beam envelope coupled from the longitudinal direction. Those have been concerned much more with the higher beam-power because of the beam loss problem. In this paper, based on the mapping data of 70 MeV cyclotron including the fringe field by BEST Cyclotron Inc (BEST) and combination magnet field by China Institute of Atomic Energy (CIAE), the beam extraction and transport are investigated for the 70 MeV cyclotron used on the SPES project at Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro (INFN-LNL). The study includes the space charge effect and longitudinal and transverse coupling mentioned above, as well as the matching of beam optics using the beam line for medical isotope production as an example. In addition, the designs of the ±45° switching magnets and the 60° bending magnet for the extracted beam with the energy from 35 MeV to 70 MeV have been made. Parts of the construction and field measurements of those magnets have been done as well. The current result shows that, the design considers the complexity of the compact cyclotron extraction area and fits the requirements of the extraction and transport for high intensity proton beam, especially at mA intensity levels.

  1. Beam Instrumentation and Diagnostics for the LHC Upgrade

    CERN Document Server

    Bravin, E; Jones, R; Lefevre, T

    2015-01-01

    The extensive array of beam instrumentation with which the LHC is equipped, has played a major role in its commissioning, rapid intensity ramp-up and safe and reliable operation. High Luminosity LHC (HL-LHC) brings with it a number of new challenges in terms of beam instrumentation that will be discussed in this chapter. The beam loss system will need significant upgrades in order to be able to cope with the demands of HL-LHC, with cryogenic beam loss monitors under investigation for deployment in the new inner triplet magnets to distinguish between primary beam losses and collision debris. Radiation tolerant integrated circuits are also being developed to allow the front-end electronics to sit much closer to the detector. Upgrades to other existing systems are also envisaged; including the beam position measurement system in the interaction regions and the addition of a halo measurement capability to synchrotron light diagnostics. Additionally, several new diagnostic systems are under investigation, such as ...

  2. Investigation of beam deflection reduction and multi-beamlet focus at a large-area negative ion source for a neutral beam injector with 3-D beam trajectory simulation

    CERN Document Server

    Tanaka, M; Asano, E; Oka, Y; Osakabe, M; Tsumori, K; Kaneko, O; Yamashita, Y

    2000-01-01

    We investigated the reduction of ion beam deflection caused by electron deflection magnets, and focus of multi-beamlets at a large-area negative ion source of a neutral beam injector (NBI) in order to reduce beam loss during long-distance beam transport (>10 m) and beam injection into a nuclear fusion device. The electrostatic lens effect by displacement of the beam extraction aperture of a grounded grid (GG) was utilized for the beam deflection reduction and the multi-beamlet focus. We proposed an analysis process to adjust the aperture displacement which avoids beam collision with the GG by too much displacement. The analysis process includes a 3-D beam trajectory simulation used for analyzing the beam deflection angle and beam radius as well as theoretical calculations, which are used to calculate the aperture displacement based on the 3-D simulation results. Applicability of the analysis process was examined for a large-area high-current H sup - ion source of an NBI (0.25 mx1.25 m, 40 A, 180 keV). The ana...

  3. 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.

  4. Coherent Beam-Beam Effects in the LHC

    CERN Document Server

    Alexahin, Yu I; Herr, Werner; Zorzano-Mier, M P

    2001-01-01

    In the Large Hadron Collider (LHC) two proton beams of similar intensities collide in several interaction points. It is well known that the head-on collision of two beams of equal strength can excite coherent modes whose frequencies are separated from the incoherent spectrum of oscillations of individual particles. This can lead to the loss of Landau damping and possibly to unstable motion. The beam-beam effect in the LHC is further complicated by a large number of bunches (2808 per beam), a finite crossing angle and gaps in the bunch train. The coherent beam-beam effects under various conditions and operational scenarios are studied analytically and with multiparticle simulations. We give an overview of the main results and present proposals to overcome these difficulties together with possible side effects.

  5. 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.

  6. 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...

  7. Hearing Loss in Children: Types of Hearing Loss

    Science.gov (United States)

    ... hearing. There are four types of hearing loss: Conductive Hearing Loss Hearing loss caused by something that stops sounds ... Hearing Loss Hearing loss that includes both a conductive and a sensorineural hearing loss. Auditory Neuropathy Spectrum Disorder Hearing loss that occurs ...

  8. Dual-beam CRT

    International Nuclear Information System (INIS)

    1975-01-01

    A dual-beam cathode-ray tube having a pair of electron guns and associated deflection means disposed side-by-side on each side of a central axis is described. The electron guns are parallel and the deflection means includes beam centering plates and angled horizontal deflection plates to direct the electron beams toward the central axis, precluding the need for a large-diameter tube neck in which the entire gun structures are angled. Bowing control plates are disposed adjacent to the beam centering plates to minimize trace bowing, and an intergun shield is disposed between the horizontal deflection plates to control and correct display pattern geometry distortion

  9. Laser beam shaping techniques

    Energy Technology Data Exchange (ETDEWEB)

    DICKEY,FRED M.; WEICHMAN,LOUIS S.; SHAGAM,RICHARD N.

    2000-03-16

    Industrial, military, medical, and research and development applications of lasers frequently require a beam with a specified irradiance distribution in some plane. A common requirement is a laser profile that is uniform over some cross-section. Such applications include laser/material processing, laser material interaction studies, fiber injection systems, optical data image processing, lithography, medical applications, and military applications. Laser beam shaping techniques can be divided into three areas: apertured beams, field mappers, and multi-aperture beam integrators. An uncertainty relation exists for laser beam shaping that puts constraints on system design. In this paper the authors review the basics of laser beam shaping and present applications and limitations of various techniques.

  10. Beam cooling

    OpenAIRE

    Danared, H

    2006-01-01

    Beam cooling is the technique of reducing the momentum spread and increasing the phase-space density of stored particle beams. This paper gives an introduction to beam cooling and Liouville’s theorem, and then it describes the three methods of active beam cooling that have been proven to work so far, namely electron cooling, stochastic cooling, and laser cooling. Ionization cooling is also mentioned briefly.

  11. Molecular beams

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  12. Beam-beam studies for FCC-hh

    CERN Document Server

    AUTHOR|(CDS)2068329; Pieloni, Tatiana; Buffat, Xavier; Furuseth, Sondre Vik

    2017-01-01

    The Future Circular Collider hadron-hadron (FCC-hh) design study is currently exploring different IR design possibilities including round and flat optics or different crossing schemes. The present study intends to evaluate each scenario from the beam-beam effects point of view. In particular the single particle long term stability to maximize beam lifetimes and luminosity reach is used to quantify the differences. The impact of strong head on interactions on the beam quality and lifetime is addressed by means of GPU accelerated simulations code featuring a weak-strong 6-dimensional beam-beam interaction.

  13. High intensity beam dump for the Tevatron beam abort system

    International Nuclear Information System (INIS)

    Kidd, J.; Mokhov, N.; Murphy, T.; Palmer, M.; Toohig, T.; Turkot, F.; VanGinneken, A.

    1981-01-01

    The beam abort system proposed for the Fermilab Tevatron Accelerator will extract the proton beam from the ring in a single turn (approximately 20/mu/s) and direct it to an external beam dump. It is the function of the beam dump to absorb the unwanted beam and limit the escaping radiation to levels that are acceptable to the surrounding populace and apparatus. A beam dump that is expected to meet these requirements has been designed and constructed. Detailed design of the dump, including considerations leading to the choice of materials, are given. 6 refs

  14. 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.

  15. 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 ...

  16. OBSERVATION OF STRONG - STRONG AND OTHER BEAM - BEAM EFFECTS IN RHIC

    International Nuclear Information System (INIS)

    FISCHER, W.; BLASKIEWICZ, M.; BRENNAN, J.M.; CAMERON, P.; CONNOLLY, R.; MONTAG, C.; PEGGS, S.; PILAT, F.; PTITSYN, V.; TEPIKIAN, S.; TRBOJEVIC, D.; VAN ZEIJTS, J.

    2003-01-01

    RHIC is currently the only hadron collider in which strong-strong beam-beam effects can be seen. For the first time, coherent beam-beam modes were observed in a bunched beam hadron collider. Other beam-beam effects in RHIC were observed in operation and in dedicated experiments with gold ions, deuterons and protons. Observations include measurements of beam-beam induced tune shifts, lifetime and emittance growth measurements with and without beam-beam interaction, and background rates as a function of tunes. During ramps unequal radio frequencies in the two rings cause the crossing points to move longitudinally. Thus bunches experience beam-beam interactions only in intervals and the tunes are modulated. In this article we summarize the most important beam-beam observations made so far

  17. Beam-beam collisions and crossing angles in RHIC

    International Nuclear Information System (INIS)

    Peggs, S.

    1999-01-01

    This paper evaluates the strength of head on and parasitic beam-beam collisions in RHIC when the crossing angle is zero. A non-zero crossing angle is not required in normal operation with 120 bunches, thanks to the early separation of the two beams. The RHIC lattice is shown to easily accommodate even conservatively large crossing angles, for example in beam dynamics studies, or in future operational upgrades to as many as 360 bunches per ring. A modest loss in luminosity is incurred when gold ions collide at an angle after 10 hours of storage

  18. A Neutral Beam Injector Upgrade for NSTX

    International Nuclear Information System (INIS)

    Stevenson, T.; McCormack, B.; Loesser, G.D.; Kalish, M.; Ramakrishnan, S.; Grisham, L.; Edwards, J.; Cropper, M.; Rossi, G.; Halle, A. von; Williams, M.

    2002-01-01

    The National Spherical Torus Experiment (NSTX) capability with a Neutral Beam Injector (NBI) capable of 80 kiloelectronvolt (keV), 5 Megawatt (MW), 5 second operation. This 5.95 million dollar upgrade reused a previous generation injector and equipment for technical, cost, and schedule reasons to obtain these specifications while retaining a legacy capability of 120 keV neutral particle beam delivery for shorter pulse lengths for possible future NSTX experiments. Concerns with NBI injection included power deposition in the plasma, aiming angles from the fixed NBI fan array, density profiles and beam shine through, orbit losses of beam particles, and protection of the vacuum vessel wall against beam impingement. The upgrade made use of the beamline and cryo panels from the Neutral Beam Test Stand facility, existing power supplies and controls, beamline components and equipment not contaminated by tritium during DT [deuterium-tritium] experiments, and a liquid Helium refrigerator plant to power and cryogenically pump a beamline and three ion sources. All of the Tokamak Fusion Test Reactor (TFTR) ion sources had been contaminated with tritium, so a refurbishment effort was undertaken on selected TFTR sources to rid the three sources destined for the NSTX NBI of as much tritium as possible. An interconnecting duct was fabricated using some spare and some new components to attach the beamline to the NSTX vacuum vessel. Internal vacuum vessel armor using carbon tiles was added to protect the stainless steel vacuum vessel from beam impingement in the absence of plasma and interlock failure. To date, the NBI has operated to 80 keV and 5 MW and has injected requested power levels into NSTX plasmas with good initial results, including high beta and strong heating characteristics at full rated plasma current

  19. The cooling of particle beams

    International Nuclear Information System (INIS)

    Sessler, A.M.

    1994-10-01

    A review is given of the various methods which can be employed for cooling particle beams. These methods include radiation damping, stimulated radiation damping, ionization cooling, stochastic cooling, electron cooling, laser cooling, and laser cooling with beam coupling. Laser Cooling has provided beams of the lowest temperatures, namely 1 mK, but only for ions and only for the longitudinal temperature. Recent theoretical work has suggested how laser cooling, with the coupling of beam motion, can be used to reduce the ion beam temperature in all three directions. The majority of this paper is devoted to describing laser cooling and laser cooling with beam coupling

  20. Beam dynamics issues for linear colliders

    International Nuclear Information System (INIS)

    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

  1. A beam source model for scanned proton beams.

    Science.gov (United States)

    Kimstrand, Peter; Traneus, Erik; Ahnesjö, Anders; Grusell, Erik; Glimelius, Bengt; Tilly, Nina

    2007-06-07

    A beam source model, i.e. a model for the initial phase space of the beam, for scanned proton beams has been developed. The beam source model is based on parameterized particle sources with characteristics found by fitting towards measured data per individual beam line. A specific aim for this beam source model is to make it applicable to the majority of the various proton beam systems currently available or under development, with the overall purpose to drive dose calculations in proton beam treatment planning. The proton beam phase space is characterized by an energy spectrum, radial and angular distributions and deflections for the non-modulated elementary pencil beam. The beam propagation through the scanning magnets is modelled by applying experimentally determined focal points for each scanning dimension. The radial and angular distribution parameters are deduced from measured two-dimensional fluence distributions of the elementary beam in air. The energy spectrum is extracted from a depth dose distribution for a fixed broad beam scan pattern measured in water. The impact of a multi-slab range shifter for energy modulation is calculated with an own Monte Carlo code taking multiple scattering, energy loss and straggling, non-elastic and elastic nuclear interactions in the slab assembly into account. Measurements for characterization and verification have been performed with the scanning proton beam system at The Svedberg Laboratory in Uppsala. Both in-air fluence patterns and dose points located in a water phantom were used. For verification, dose-in-water was calculated with the Monte Carlo code GEANT 3.21 instead of using a clinical dose engine with approximations of its own. For a set of four individual pencil beams, both with the full energy and range shifted, 96.5% (99.8%) of the tested dose points satisfied the 1%/1 mm (2%/2 mm) gamma criterion.

  2. Studies of beam dynamics in relativistic klystron two-beam accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Lidia, Steven M.

    1999-11-01

    Two-beam accelerators (TBAs) based upon free-electron lasers (FELs) or relativistic klystrons (RK-TBAs) have been proposed as efficient power sources for next generation high-energy linear colliders. Studies have demonstrated the possibility of building TBAs from X-band (~8-12 GHz) through Ka band (~ 30-35 GHz) frequency regions. Provided that further prototyping shows stable beam propagation with minimal current loss and production of good quality, high-power rf fields, this technology is compatible with current schemes for electron-positron colliders in the multi-TeV center-of-mass scale. A new method of simulating the beam dynamics in accelerators of this type has been developed in this dissertation. There are three main components to this simulation. The first is a tracking algorithm to generate nonlinear transfer maps for pushing noninteracting particles through the external fields. The second component is a 3D Particle-In-Cell (PIC) algorithm that solves a set of Helmholtz equations for the self-fields, including the conducting boundary condition, and generates impulses that are interleaved with the nonlinear maps by means of a split-operation algorithm. The Helmholtz equations are solved by a multi-grid algorithm. The third component is an equivalent circuit equation solver that advances the modal rf cavity fields in time due to excitation by the modulated beam. The RTA project is described, and the simulation code is used to design the latter portions of the experiment. Detailed calculations of the beam dynamics and of the rf cavity output are presented and discussed. A beamline design is presented that will generate nearly 1.2 GW of power from 40 input, gain, and output rv cavities over a 10 m distance. The simulations show that beam current losses are acceptable, and that longitudinal and transverse focusing techniques are sufficient capable of maintaining a high degree of beam quality along the entire beamline. Additional experimental efforts are also

  3. Beam diagnostics

    International Nuclear Information System (INIS)

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

    1995-01-01

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

  4. Hearing loss

    Science.gov (United States)

    Decreased hearing; Deafness; Loss of hearing; Conductive hearing loss; Sensorineural hearing loss; Presbycusis ... Conductive hearing loss (CHL) occurs because of a mechanical problem in the outer or middle ear. This may be ...

  5. LHC beam dump system : analysis of beam commissioning, performance and the consequences of abnormal operation

    International Nuclear Information System (INIS)

    Kramer, T.

    2011-01-01

    The LHC accelerates proton beams to a momentum of up to 7 TeV/c. At this energy level and with nominal beam intensity the stored energy of 360 MJ per beam is sufficient to melt 500 kg of copper. In addition up to 10 GJ are stored within the LHC magnet system at top energy. lt is obvious that such a machine needs well designed safety and protection systems. The LHC Beam Dump System (LBDS) is such a system and one of the most critical once concerning machine protection and safe operation. lt is used to dispose of high intensity beams between 450 GeV and 7 TeV and is thus designed to fast extract beam in a loss free way and to transfer it to an external absorber. For each ring systems of 15 horizontal fast kicker magnets (MKD), 15 vertically deflecting magnetic septa (MSD) and 10 diluter kicker magnets (MKB) are installed. This thesis is concerned with the analysis of the LBDS performance under normal operating parameters as well as under abnormal conditions like in the event of asynchronous beam abort or missing MKD elements. Therefore a sophisticated simulation environment was developed based on the use of the MAD-X tracking code. A system of tracking jobs was set up to study failure cases and losses for various dump events. Those jobs can be distributed to available CPU power and be calculated in parallel. Studies into the consequences of abnormal beam dump actions have been performed. Different error scenarios have been evaluated including an asynchronous dump action, prefire cases, and the impact of different orbit and collimator settings. Losses at locations in the ring and the beam dump transfer lines have been quantified as a function of different settings of the dump system protection elements. The implications for the setup and operation of these protection elements are discussed. Particle distributions can be created according to the used orbit. Simulations with different orbit parameters (including magnet field errors, beam position read out errors

  6. Surface Resistance Measurements and Estimate of the Beam-Induced Resistive Wall Heating of the LHC Dipole Beam Screen

    CERN Document Server

    Caspers, Friedhelm; Ruggiero, F; Tan, J

    1999-01-01

    An estimate of the resistive losses in the LHC beam screen is given from cold surface resistance measurements using the shielded pair technique, with particular emphasis on the effect of a high magnetic field. Two different copper coating methods, namely electro-deposition and co-lamination, have been evaluated. Experimental data are compared with theories including the anomalous skin effect and the magneto-resistance effect. It is shown whether the theory underestimates or not the losses depends strongly on the RRR value, on the magnetic field and on the surface characteristics. In the pessimistic case and for nominal machine parameters, the estimated beam-induced resistive wall heating can be as large as 260 mW/m for two circulating beams.

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

    Science.gov (United States)

    Hwang, Kilean; Qiang, Ji

    2017-04-01

    A recirculating superconducting linear accelerator with the advantage of both straight and circular accelerator has been demonstrated with relativistic electron beams. The acceleration concept of a recirculating proton beam was recently proposed [J. Qiang, Nucl. Instrum. Methods Phys. Res., Sect. A 795, 77 (2015, 10.1016/j.nima.2015.05.056)] and is currently under study. In order to further support the concept, the beam dynamics study on a recirculating proton linear accelerator has to be carried out. In this paper, we study the feasibility of a two-pass recirculating proton linear accelerator through the direct numerical beam dynamics design optimization and the start-to-end simulation. This study shows that the two-pass simultaneous focusing without particle losses is attainable including fully 3D space-charge effects through the entire accelerator system.

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

    Directory of Open Access Journals (Sweden)

    Kilean Hwang

    2017-04-01

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

  9. LHC beam dump system Consequences of abnormal operation

    CERN Document Server

    Kramer, T; Uythoven, J

    2010-01-01

    The LHC beam dump system is one of the most critical systems concerning machine protection and safe operation. It is used to dispose of high intensity beams between 450 GeV and 7 TeV. Studies into the consequences of abnormal beam dump actions have been performed. Different error scenarios have been evaluated using particle tracking in MAD-X, including an asynchronous dump action, and the impact of different orbit and collimator settings. Losses at locations in the ring and the beam dump transfer lines have been quantified as a function of different settings of the dump system protection elements. The implications for the setting up and operation of these protection elements are discussed.

  10. Polarized proton beams

    International Nuclear Information System (INIS)

    Roser, T.

    1995-01-01

    The acceleration of polarized proton beams in circular accelerators is complicated by the presence of numerous depolarizing spin resonances. Careful and tedious minimization of polarization loss at each of these resonances allowed acceleration of polarized proton beams up to 22 GeV. It has been the hope that Siberian Snakes, which are local spin rotators inserted into ring accelerators, would eliminate these resonances and allow acceleration of polarized beams with the same ease and efficiency that is now routine for unpolarized beams. First tests at IUCF with a full Siberian Snake showed that the spin dynamics with a Snake can be understood in detail. The author now has results of the first tests of a partial Siberian Snake at the AGS, accelerating polarized protons to an energy of about 25 GeV. These successful tests of storage and acceleration of polarized proton beams open up new possibilities such as stored polarized beams for internal target experiments and high energy polarized proton colliders

  11. Beam director design report

    International Nuclear Information System (INIS)

    Younger, F.C.

    1986-08-01

    A design and fabrication effort for a beam director is documented. The conceptual design provides for the beam to pass first through a bending and focusing system (or ''achromat''), through a second achromat, through an air-to-vacuum interface (the ''beam window''), and finally through the vernier steering system. Following an initial concept study for a beam director, a prototype permanent magnet 30 0 beam-bending achromat and prototype vernier steering magnet were designed and built. In volume II, copies are included of the funding instruments, requests for quotations, purchase orders, a complete set of as-built drawings, magnetic measurement reports, the concept design report, and the final report on the design and fabrication project

  12. Beam director design report

    Energy Technology Data Exchange (ETDEWEB)

    Younger, F.C.

    1986-08-01

    A design and fabrication effort for a beam director is documented. The conceptual design provides for the beam to pass first through a bending and focusing system (or ''achromat''), through a second achromat, through an air-to-vacuum interface (the ''beam window''), and finally through the vernier steering system. Following an initial concept study for a beam director, a prototype permanent magnet 30/sup 0/ beam-bending achromat and prototype vernier steering magnet were designed and built. In volume II, copies are included of the funding instruments, requests for quotations, purchase orders, a complete set of as-built drawings, magnetic measurement reports, the concept design report, and the final report on the design and fabrication project. (LEW)

  13. Multi-turn losses and cleaning in 2011 and 2012

    CERN Document Server

    Valentino, G; Bellodi, G; Bruce, R; Burkart, F; Cauchi, M; Deboy, D; Jowett, J M; Lari, L; Redaelli, S; Rossi, A; Salvachua Ferrando, B; Wollmann, D

    2012-01-01

    LHC beam collimation is based on a hierarchical multistage cleaning system. Maintaining the correct hierarchy ensures maximal cleaning efficiency and machine protection. The operational collimator positions are established from the beam centres and sizes at each collimator measured in beam-based alignments. These are verified periodically during the year. The improvements made to the collimator alignment algorithm in 2011 are described. The time spent on setup and qualification by loss maps is summarized in detail. The stability of the collimator setup and cleaning efficiency is presented. An outlook to 2012 is given, including detailed considerations on improved setup speed, required frequency of setup and qualification and other possible improvements overall reducing beam time consumption for collimation.

  14. Elliptical beams.

    Science.gov (United States)

    Bandres, Miguel A; Gutiérrez-Vega, Julio C

    2008-12-08

    A very general beam solution of the paraxial wave equation in elliptic cylindrical coordinates is presented. We call such a field an elliptic beam (EB). The complex amplitude of the EB is described by either the generalized Ince functions or the Whittaker-Hill functions and is characterized by four parameters that are complex in the most general situation. The propagation through complex ABCD optical systems and the conditions for square integrability are studied in detail. Special cases of the EB are the standard, elegant, and generalized Ince-Gauss beams, Mathieu-Gauss beams, among others.

  15. APPLICATION OF UAL TO HIGH INTENSITY BEAM DYNAMICS STUDIES IN THE SNS ACCUMULATOR RING

    International Nuclear Information System (INIS)

    MALITSKY, N.; FEDOTOV, A.V.; WEI, J.

    2002-01-01

    The SNS Ring off-line parallel simulation environment based on the Unified Accelerator Libraries (UAL) has been implemented and used for extensive full-scale beam dynamics studies arising in high-intensity rings. The paper describes the structure of this environment and its application to the development and analysis of the SNS accumulator ring beam loss model including a complex combination of several physical effects

  16. APPLICATION OF UAL TO HIGH INTENSITY BEAM DYNAMICS STUDIES IN THE SNS ACCUMULATOR RING.

    Energy Technology Data Exchange (ETDEWEB)

    MALITSKY,N.; FEDOTOV,A.V.; WEI,J.

    2002-06-03

    The SNS Ring off-line parallel simulation environment based on the Unified Accelerator Libraries (UAL) has been implemented and used for extensive full-scale beam dynamics studies arising in high-intensity rings. The paper describes the structure of this environment and its application to the development and analysis of the SNS accumulator ring beam loss model including a complex combination of several physical effects.

  17. Subharmonic beam-loading in electron linear accelerators

    International Nuclear Information System (INIS)

    Gallagher, W.J.

    1983-01-01

    The intention of operating an electron linear accelerator subharmonically beam loaded for free electron laser application requires justification of the beam-loaded energy gain equation. The mode of operation typically planned is 5 to 10 nanocoulombs single RF cycle pulses at 25 to 50 nanosecond intervals. This inquiry investigates the details of this sort of beam loading and discusses the performance achievable. Several other investigations of single bunch beam loading have been undertaken, notably at SLAC, where it has been found experimentally that the beam-loading varies directly as the bunch charge and independently of its energy; that investigation also included radiation effects of the wake field and losses owing to parasitic effects of higher order modes. In the case of beam loading where there are multiple pulses transiting at the same time, and spaced far enough apart that significant RF power is introduced between pulses, the energy gain may be calculated by dividing the waveguide into a number of segments, each equal in length to the integral of the interpulse time and the local group velocity. Equations which reveal that the net energy gain in the steady state is the sum of the energy gains in these segments, which compute the initial field intensity, and which calculate the energy gain in the subharmonic case on the basis of the equivalent beam current are presented

  18. Lithium beam diagnostic system on the COMPASS tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Anda, G.; Bencze, A. [Wigner – RCP, HAS, Budapest (Hungary); Berta, M., E-mail: bertam@sze.hu [Institute of Plasma Physics AS CR, Prague (Czech Republic); Széchenyi István University, Győr (Hungary); Dunai, D. [Wigner – RCP, HAS, Budapest (Hungary); Hacek, P. [Institute of Plasma Physics AS CR, Prague (Czech Republic); Faculty of Mathematics and Physics, Charles University in Prague, Prague (Czech Republic); Krbec, J. [Institute of Plasma Physics AS CR, Prague (Czech Republic); Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague (Czech Republic); Réfy, D.; Krizsanóczi, T.; Bató, S.; Ilkei, T.; Kiss, I.G.; Veres, G.; Zoletnik, S. [Wigner – RCP, HAS, Budapest (Hungary)

    2016-10-15

    Highlights: • Li-beam diagnostic system on the COMPASS tokamak is an improved and compact system to allow testing of Atomic Beam Probe. • The possibility to measure background corrected density profiles on the few microseconds time scale. • First Li-beam diagnostic system with recirculating neutralizer. • The system includes the redesigned ion source with longer lifetime. - Abstract: An improved lithium beam based beam emission spectroscopy system – installed on COMPASS tokamak – is described. The beam energy enhanced up to 120 keV for Atomic Beam Probe measurement. The size of the ion source is doubled, using a newly developed thermionic heater instead of the conventionally used heating (tungsten or molybdenum) filament. The neutralizer is also improved. It produces the same sodium vapor in a cell but minimize the loss condensing the vapor on a cold surface which is led back (in fluid state) into the sodium oven. This way we call it recirculating neutralizer. The observation system consists of a CCD camera and an avalanche photodiode array.

  19. Beam Dynamics Simulation for the CTF3 Drive Beam Accelerator

    CERN Document Server

    Schulte, Daniel

    2000-01-01

    A new CLIC Test Facility (CTF3) at CERN will serve to study the drive beam generation for the Compact Linear Collider (CLIC). CTF3 has to accelerate a 3.5 A electron beam in almost fully-loaded structures. The pulse contains more than 2000 bunches, one in every second RF bucket, and has a length of more than one microsecond. Different options for the lattice of the drive-beam accelerator are presented, based on FODO-cells and triplets as well as solenoids. The transverse stability is simulated, including the effects of beam jitter, alignment and beam-based correction.

  20. ASR DIAGNOSIS BY PETROGRAPHIC INVESTIGATION AND EVALUATION OF MECHANICAL PERFORMANCE OF ASR DETERIORATED PRETENSIONED PC BEAM

    Science.gov (United States)

    Tomiyama, Jun; Yamada, Kazuo; Kaneda, Kazuo; Iraha, Shigeo; Oshiro, Takeshi

    ASR diagnosis and evaluation of load carrying capacity have been performed on the pre-tensioned PC beam which was cut out of a national high way bridge. The bridge was replaced lately after 25years service due to ASR deterioration. Comprehensive investigations such as crack measurement, material strength test, petrographic investigation, beam bending test have been performed on the deteriorated beam. Cracks have been observed on all sides and the appearance has been classified as severe deterioration grade. Petrographic investigation concluded that the reacted mineral was mainly reactive cristobalite contained in andesite of fine aggregates and EPMA investigation found that the reaction seemed to be the final stage. The late expansive ASR has been superimposed by cryptocrystalline quartz in coarse aggregates and it is still in progress. Deteriorated concrete cores with no visual crack have reduced only 10% of compressive strength compared with design strength, but significant loss has been observed on the elastic modulus. The static bending load test on the deteriorated test beam showed 95% of design load capacity indicating that the visual deterioration on surfaces has affected slight damages at this moment. But loss of bending rigidity has been appeared on the deteriorated beam .after bending cracks have started. This comprehensive study including the petrographic diagnosis and the appraisal on mechanical performance of the deteriorated beam conclude that there is a possibility of ASR deterioration in progress and further loss of mechanical performance though the beam had some margin for loading capacity at this moment.

  1. Beam halo studies in LEHIPA DTL

    Science.gov (United States)

    Roy, S.; Pande, R.; Rao, S. V. L. S.; Krishnagopal, S.; Singh, P.

    2015-11-01

    The Low Energy High Intensity Proton Accelerator (LEHIPA) project at Bhabha Atomic Research Centre (BARC) consists of a 20 MeV, 30 mA proton linac. The accelerator comprises of a 3 MeV Radio Frequency Quadrupole (RFQ) and a 20 MeV Drift Tube Linac (DTL). In such high intensity accelerators, beam halos are of concern as they not only cause an increase in emittance, but also lead to beam loss and radio activation. We have studied the effect of beam mismatch at the DTL input on halo formation and propagation. The particle core model is used to excite the three envelope eigen modes; the quadrupole mode, the fast mode and the slow mode by giving input beam mismatch. These modes get damped as the beam progresses through the DTL. The damping mechanism is clearly Landau damping and leads to increase in rms emittance of the beam. The evolution of these modes and the corresponding increase in beam emittance and maximum beam extent, as the beam propagates through the DTL, has been studied for different space charge tunes. The halo parameter based on the definition of Allen and Wangler has been calculated. It is seen that beam halos are very important for LEHIPA DTL, even at 20 MeV and leads to emittance and beam size increase and also to beam loss in some cases. The longitudinal halo is present even without mismatch and transverse halos arise in the presence of beam mismatch.

  2. Stationary nonlinear Airy beams

    International Nuclear Information System (INIS)

    Lotti, A.; Faccio, D.; Couairon, A.; Papazoglou, D. G.; Panagiotopoulos, P.; Tzortzakis, S.; Abdollahpour, D.

    2011-01-01

    We demonstrate the existence of an additional class of stationary accelerating Airy wave forms that exist in the presence of third-order (Kerr) nonlinearity and nonlinear losses. Numerical simulations and experiments, in agreement with the analytical model, highlight how these stationary solutions sustain the nonlinear evolution of Airy beams. The generic nature of the Airy solution allows extension of these results to other settings, and a variety of applications are suggested.

  3. Evolution of a beam dynamics model for the transport line in a proton therapy facility

    Science.gov (United States)

    Rizzoglio, V.; Adelmann, A.; Baumgarten, C.; Frey, M.; Gerbershagen, A.; Meer, D.; Schippers, J. M.

    2017-12-01

    During the conceptual design of an accelerator or beamline, first-order beam dynamics models are essential for studying beam properties. However, they can only produce approximate results. During commissioning, these approximate results are compared to measurements, which will rarely coincide if the model does not include the relevant physics. It is therefore essential that this linear model is extended to include higher-order effects. In this paper, the effects of particle-matter interaction have been included in the model of the transport lines in the proton therapy facility at the Paul Scherrer Institut (PSI) in Switzerland. The first-order models of these beamlines provide an approximated estimation of beam size, energy loss and transmission. To improve the performance of the facility, a more precise model was required and has been developed with opal (Object Oriented Parallel Accelerator Library), a multiparticle open source beam dynamics code. In opal, the Monte Carlo simulations of Coulomb scattering and energy loss are performed seamless with the particle tracking. Beside the linear optics, the influence of the passive elements (e.g., degrader, collimators, scattering foils, and air gaps) on the beam emittance and energy spread can be analyzed in the new model. This allows for a significantly improved precision in the prediction of beam transmission and beam properties. The accuracy of the opal model has been confirmed by numerous measurements.

  4. Beam-beam simulations: dynamical effects and beam-beam limit for LEP3

    CERN Document Server

    Ohmi, K

    2012-01-01

    Beam-beam simulations are reported for LEP3 and TLEP-H, including a rough tune scan. The results suggest that to achieve the design luminosity in LEP3, 10% higher bunch population may be necessary, while TLEP-H can achieve the design performance without any changes. The simulations indicate that the large synchrotron tune, in conjunction with a large hourglass effect, degrades the luminosity performance. This talk was given at CERN on 4 December 2012.

  5. PARTICLE BEAMS: Frontier course

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    Driven by the quest for higher energies and optimal physics conditions, the behaviour of particle beams in accelerators and storage rings is the subject of increasing attention. Thus the second course organized jointly by the US and CERN Accelerator Schools looked towards the frontiers of particle beam knowledge. The programme held at South Padre Island, Texas, from 23-29 October attracted 125 participants including some 35 from Europe

  6. Beam heating studies on an early model is a superconducting cosine theta magnet

    International Nuclear Information System (INIS)

    Bozoki, G.; Bunce, G.; Danby, G.; Foelsche, H.; Jackson, J.; Prodell, A.; Soukas, A.; Stevens, A.; Stoehr, R.; Weisenbloom, J.

    1980-01-01

    Superconducting magnets for accelerators can be accidentally quenched by heat resulting from beam losses in the magnet. The threshold for such quenches is determined by the time structure of the beam loss and by details of the magnet application, construction and cooling. A 4.25 m long superconducting cosine theta dipole magnet, MARK VI, constructed during the research and development phase of the ISABELLE Project at BNL was installed in the 28.5 GeV/c primary proton beam line from the AGS. By energizing the magnet, the proton beam could be deflected into the magnet. The beam intensity required to quench the magnet was observed for different beam sizes and at several values of magnet current up to 2400 A or approximately 70% of the highest magnet operating current. The maximum current was limited by the gas-cooled power lead flow available using pool-boiling helium rather than single phase forced-flow helium at 5 atm for which the magnet system was designed. Details of the experimental setup including the magnet and cryogenic system, the beam-monitoring equipment and instrumentation are described. The measurements are discussed and compared with beam heating measurements made on another superconducting magnet and interpreted using the Cascade Simulation Program, CASIM

  7. Beam loading effects for two-beam ring

    International Nuclear Information System (INIS)

    Wang Lanfa; Lin Yuzheng; Tong Dechun

    1999-01-01

    An analytic treatment of multi-bunch potential well distortion for a two-beam storage ring is presented. The longitudinal wake effects are separated into: the mode loss, the synchrotron tune shift (both due to potential well distortion) and the coherent multi-bunch coupling. Here, only the first two effects are studied. Resulting simple analytic formulas describe the mode loss and the synchrotron tune shift experienced by a given bunch within the two-beam, as a function of the high order mode's parameters. One can get immediately a simple quantitative answer in term of the mode loss and the synchrotron tune shift experienced by each bunch from these formulas, so the authors can know how to modify the existing configuration of parasitic cavity resonance (via frequency tuning) so that the resulting potential well distortion effects are minimized. When the RF cavities are symmetrically distributed about the interaction points, the two beams will have same beam loading effects, so the authors can compensate the phase shift of the two beam using the same method as in one beam case

  8. Applications of electron lenses: scraping of high-power beams, beam-beam compensation, and nonlinear optics

    Energy Technology Data Exchange (ETDEWEB)

    Stancari, Giulio

    2014-09-11

    Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Hollow electron beam collimation and halo control were studied as an option to complement the collimation system for the upgrades of the Large Hadron Collider (LHC) at CERN; a conceptual design was recently completed. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compensation in LHC luminosity upgrade scenarios with small crossing angles. At Fermilab, we are planning to install an electron lens in the Integrable Optics Test Accelerator (IOTA, a 40-m ring for 150-MeV electrons) as one of the proof-of-principle implementations of nonlinear integrable optics to achieve large tune spreads and more stable beams without loss of dynamic aperture.

  9. Energy deposition of heavy ions in the regime of strong beam-plasma correlations.

    Science.gov (United States)

    Gericke, D O; Schlanges, M

    2003-03-01

    The energy loss of highly charged ions in dense plasmas is investigated. The applied model includes strong beam-plasma correlation via a quantum T-matrix treatment of the cross sections. Dynamic screening effects are modeled by using a Debye-like potential with a velocity dependent screening length that guarantees the known low and high beam velocity limits. It is shown that this phenomenological model is in good agreement with simulation data up to very high beam-plasma coupling. An analysis of the stopping process shows considerably longer ranges and a less localized energy deposition if strong coupling is treated properly.

  10. Damping of coherent oscillations in intense ion beams

    International Nuclear Information System (INIS)

    Karpov, Ivan

    2017-01-01

    Transverse decoherence of a displaced ion bunch is an important phenomenon in synchrotrons and storage rings. An offset can be caused by an injection error after the bunch-to-bucket transfer between synchrotrons or by an externally generated kick. Decoherence results in a transverse emittance blowup, which can cause particle losses and a beam quality degradation. To prevent the beam blowup, a transverse feedback system (TFS) can be used. The damping time should be shorter than the characteristic decoherence time, which can be strongly affected by the interplay of different intensity effects (e.g., space charge and impedances). This thesis describes the development of the analytical models that explain decoherence and emittance growth with chromaticity, space charge, and image charges within the first synchrotron period. The pulsed response function including intensity effects was derived from the model for beam transfer functions. For a coasting beam, the two- dimensional model shows that space charge slows down and above intensity threshold suppresses decoherence. These predictions were confirmed by particle tracking simulations with self-consistent space charge fields. Additionally, halo buildup and losses during decoherence were observed in simulations. These effects were successfully interpreted using a non self-consistent particle-core model. The two-dimensional model was extended to the bunched beams. The simulation results reproduce the analytical predictions. The intensity threshold of decoherence suppression is higher in comparison to a coasting beam, image charges can restore decoherence. In the present work dedicated experiments were performed in the SIS18 synchrotron at GSI Darmstadt and the results were compared with simulations and analytical predictions. The contribution of nonlinearities and image charges is negligible while chromaticity and space charge dominate decoherence. To study the damping efficiency of TFS, a comprehensive TFS module was

  11. Beam Delivery Simulation: BDSIM - Development & Optimization

    CERN Document Server

    Nevay, Laurence James; Garcia-Morales, H; Gibson, S M; Kwee-Hinzmann, R; Snuverink, J; Deacon, L C

    2014-01-01

    Beam Delivery Simulation (BDSIM) is a Geant4 and C++ based particle tracking code that seamlessly tracks particles through accelerators and detectors, including the full range of particle interaction physics processes from Geant4. BDSIM has been successfully used to model beam loss and background conditions for many current and future linear accelerators such as the Accelerator Test Facility 2 (ATF2) and the International Linear Collider (ILC). Current developments extend its application for use with storage rings, in particular for the Large Hadron Collider (LHC) and the High Luminosity upgrade project (HL-LHC). This paper presents the latest results from using BDSIM to model the LHC as well as the developments underway to improve performance.

  12. Intra-beam Scattering Theory and RHIC Experiments

    International Nuclear Information System (INIS)

    Wei, J.; Fedotov, A.; Fischer, W.; Malitsky, N.; Parzen, G.; Qiang, J.

    2005-01-01

    Intra-beam scattering is the leading mechanism limiting the luminosity in heavy-ion storage rings like the Relativistic Heavy Ion Collider (RHIC). The multiple Coulomb scattering among the charged particles causes transverse emittance growth and longitudinal beam de-bunching and beam loss, compromising machine performance during collision. Theoretically, the original theories developed by Piwinski, Bjorken, and Mtingwa only describe the rms beam size growth of an unbounded Gaussian distribution. Equations based on the Fokker-Planck approach are developed to further describe the beam density profile evolution and beam loss. During the 2004 RHIC heavy-ion operation, dedicated IBS experiments were performed to bench-mark the rms beam size growth, beam loss, and profile evolution both for a Gaussian-like and a longitudinal hollow beam. This paper summarizes the IBS theory and discusses the experimental bench-marking results

  13. Operational beams for the LHC

    CERN Document Server

    Papaphilippou, Y.; Rumolo, G.; Manglunki, D.

    2014-01-01

    The variety of beams, needed to set-up in the injectors as requested in the LHC, are reviewed, in terms of priority but also performance expectations and reach during 2015. This includes the single bunch beams for machine commissioning and measurements (probe, Indiv) but also the standard physics beams with 50 ns and 25 ns bunch spacing and their high brightness variants using the Bunch Compression Merging and Splitting (BCMS) scheme. The required parameters and target performance of special beams like the doublet for electron cloud enhancement and the more exotic 8b$\\oplus$4e beam, compatible with some post-scrubbing scenarios are also described. The progress and plans for the LHC ion production beams during 2014-2015 are detailed. Highlights on the current progress of the setting up of the various beams are finally presented with special emphasis on potential performance issues across the proton and ion injector chain.

  14. Modeling the interaction of high power ion or electron beams with solid target materials

    International Nuclear Information System (INIS)

    Hassanein, A.M.

    1983-11-01

    Intense energy deposition on first wall materials and other components as a result of plasma disruptions in magnetic fusion devices are expected to cause melting and vaporization of these materials. The exact amount of vaporization losses and melt layer thickness are very important to fusion reactor design and lifetime. Experiments using ion or electron beams to simulate the disruption effects have different environments than the actual disruption conditions in fusion reactors. A model has been developed to accurately simulate the beam-target interactions so that the results from such experiments can be meaningful and useful to reactor design. This model includes a two dimensional solution of the heat conduction equation with moving boundaries. It is found that the vaporization and melting of the sample strongly depends on the characteristics of the beam spatial distribution, beam diameter, and on the power-time variation of the beam

  15. The development of MEMS device packaging technology using proton beam

    International Nuclear Information System (INIS)

    Hyeon, J. W.; Kong, Y. J.; Kim, E. H.; Kim, H. S.; No, S. J.

    2006-05-01

    Wafer-bonding techniques are key issues for the commercialization of MEMS(MicroElectroMechanical Systems) devices. The anodic bonding method and the wafer direct-bonding method are well-known major techniques for wafer bonding. Due to the anodic bonding method includes high voltage processes above 1.5 kV, the MEMS devices can be damaged during the bonding process or malfunctioned while long-term operation. On the other hand, since the wafer direct-bonding method includes a high temperature processes above 1000 .deg. C, temperature-sensitive materials and integrated circuits will be damaged or degraded during the bonding processes. Therefore, high-temperature bonding processes are not applicable for fabricating or packaging devices where temperature-sensitive materials exist. During the past few years, much effort has been undertaken to find a reliable bonding process that can be conducted at a low temperature. Unfortunately, these new bonding processes depend highly on the bonding material, surface treatment and surface flatness. In this research, a new packaging method using proton beam irradiation is proposed. While the energy loss caused in an irradiated material by X-rays or electron beams decreases with the surface distance, the energy loss caused by proton beams has a maximum value at the Bragg peak. Thus, the localized energy produced at the Bragg peak of the proton beams can be used to bond pyrex glass on a silicon wafer, so the MEMS damage is expected to be minimized. The localized heating caused by as well as the penetration depth, or the proton beam has been investigated. The energy absorbed in a stack of pyrex glass/silicon wafers due to proton-beam irradiation was numerically calculated for various proton energies by using the SRIM program. The energy loss was shown to be sufficiently localized at the interface between the pyrex glass and the silicon wafer. Proton beam irradiation was performed in the common environment of room temperature and

  16. LHC Report: Freshly squeezed beams!

    CERN Multimedia

    Mike Lamont for the LHC Team

    2011-01-01

    After careful validation of  new machine settings, the LHC was ready for higher luminosity operation. New luminosity records have been set, but the operations team continues to wrestle with machine availability issues.   The commissioning of the squeeze to a ß* of 1 m in ATLAS and CMS described in the last Bulletin took until Wednesday, 7 September to complete. In order to validate the new set-up, beam losses were provoked in a controlled way with low intensity beams. The distribution of beam loss around the machine in these tests is known as a loss map. The loss maps showed that the collimation system is catching the large majority of beam losses as it should, and that the machine was ready for us to ramp the number of bunches back up and go to physics production. The ramp-up of the number of bunches went smoothly with fills at 264, 480, and 912 bunches on the way back to the machine’s previous record of 1380 bunches (first fill on Friday, 9 Se...

  17. Intensive Ion Beam In Storage Rings With Electron Cooling

    CERN Document Server

    Korotaev, Yu V; Kamerdjiev, V; Maier, R; Meshkov, I; Noda, K; Prasuhn, D; Sibuya, S; Sidorin, A; Stein, H J; Stockhorst, H; Syresin, E M; Uesugi, T

    2004-01-01

    Results of experimental studies of the electron cooling of a proton beam at COSY (Juelich, Germany) and an ion beam at HIMAC (Chiba, Japan) are presented. Intensity of the ion beam is limited by two general effects: particle loss directly after the injection and development of instability in a deep cooled ion beam. Methods of the instability suppression, which allow increasing the cooled beam intensity, are described.

  18. Envelope model for passive magnetic focusing of an intense proton or ion beam propagating through thin foils

    Directory of Open Access Journals (Sweden)

    Steven M. Lund

    2013-04-01

    Full Text Available Ion beams (including protons with low emittance and high space-charge intensity can be propagated with normal incidence through a sequence of thin metallic foils separated by vacuum gaps of order the characteristic transverse beam extent to transport/collimate the beam or to focus it to a small transverse spot. Energetic ions have sufficient range to pass through a significant number of thin foils with little energy loss or scattering. The foils reduce the (defocusing radial electric self-field of the beam while not altering the (focusing azimuthal magnetic self-field of the beam, thereby allowing passive self-beam focusing if the magnetic field is sufficiently strong relative to the residual electric field. Here we present an envelope model developed to predict the strength of this passive (beam generated focusing effect under a number of simplifying assumptions including relatively long pulse duration. The envelope model provides a simple criterion for the necessary foil spacing for net focusing and clearly illustrates system focusing properties for either beam collimation (such as injecting a laser-produced proton beam into an accelerator or for magnetic pinch focusing to a small transverse spot (for beam driven heating of materials. An illustrative example is worked for an idealization of a recently performed laser-produced proton-beam experiment to provide guidance on possible beam focusing and collimation systems. It is found that foils spaced on the order of the characteristic transverse beam size desired can be employed and that envelope divergence of the initial beam entering the foil lens must be suppressed to limit the total number of foils required to practical values for pinch focusing. Relatively modest proton-beam current at 10 MeV kinetic energy can clearly demonstrate strong magnetic pinch focusing achieving a transverse rms extent similar to the foil spacing (20–50  μm gaps in beam propagation distances of tens of mm

  19. Photon beam position monitor

    Science.gov (United States)

    Kuzay, Tuncer M.; Shu, Deming

    1995-01-01

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

  20. Collider and detector protection at beam accidents

    International Nuclear Information System (INIS)

    Rakhno, I.L.; Mokhov, N.V.; Drozhdin, A.I.

    2003-01-01

    Dealing with beam loss due to abort kicker prefire is considered for hadron colliders. The prefires occurred at Tevatron (Fermilab) during Run I and Run II are analyzed and a protection system implemented is described. The effect of accidental beam loss in the Large Hadron Collider (LHC) at CERN on machine and detector components is studied via realistic Monte Carlo calculations. The simulations show that beam loss at an unsynchronized beam abort would result in severe heating of conventional and superconducting magnets and possible damage to the collider detector elements. A proposed set of collimators would reduce energy deposition effects to acceptable levels. Special attention is paid to reducing peak temperature rise within the septum magnet and minimizing quench region length downstream of the LHC beam abort straight section

  1. Collider and Detector Protection at Beam Accidents

    International Nuclear Information System (INIS)

    Rakhno, I.L.; Mokhov, N.V.; Drozhdin, A.I.

    2003-01-01

    Dealing with beam loss due to abort kicker prefire is considered for hadron colliders. The prefires occurred at Tevatron (Fermilab) during Run I and Run II are analyzed and a protection system implemented is described. The effect of accidental beam loss in the Large Hadron Collider (LHC) at CERN on machine and detector components is studied via realistic Monte Carlo calculations. The simulations show that beam loss at an unsynchronized beam abort would result in severe heating of conventional and superconducting magnets and possible damage to the collider detector elements. A proposed set of collimators would reduce energy deposition effects to acceptable levels. Special attention is paid to reducing peak temperature rise within the septum magnet and minimizing quench region length downstream of the LHC beam abort straight section

  2. Quantum beams

    International Nuclear Information System (INIS)

    Uesaka, Mitsuru

    2003-01-01

    Present state and future prospect are described on quantum beams for medical use. Efforts for compactness of linac for advanced cancer therapy have brought about the production of machines like Accuray's CyberKnife and TOMOTHERAPY (Tomo Therapy Inc.) where the acceleration frequency of X-band (9-11 GHz) is used. For cervical vein angiography by the X-band linac, a compact hard X-ray source is developed which is based on the (reverse) Compton scattering through laser-electron collision. More intense beam and laser are necessary at present. A compact machine generating the particle beam of 10 MeV-1 GeV (laser-plasma accelerator) for cancer therapy is also developed using the recent compression technique (chirped-pulse amplification) to generate laser of >10 TW. Tokyo University is studying for the electron beam with energy of GeV order, for the laser-based synchrotron X-ray, and for imaging by the short pulse ion beam. Development of advanced compact accelerators is globally attempted. In Japan, a virtual laboratory by National Institute of Radiological Sciences (NIRS), a working group of universities and research facilities through the Ministry of Education, Culture, Sports, Science and Technology, started in 2001 for practical manufacturing of the above-mentioned machines for cancer therapy and for angiography. Virtual Factory (Inc.), a business venture, is to be stood in future. (N.I.)

  3. Recurrent pregnancy loss

    DEFF Research Database (Denmark)

    Egerup, Pia; Kolte, A M; Larsen, E C

    2016-01-01

    immunoglobulin (IvIg) conducted from 1991 to 2014. No other treatments were given. Patients with documented explained pregnancy losses (ectopic pregnancies and aneuploid miscarriages) were excluded. PARTICIPANTS/MATERIALS, SETTING, METHODS: Of the 168 patients included in the trials, 127 had secondary RPL......STUDY QUESTION: Is there a different prognostic impact for consecutive and non-consecutive early pregnancy losses in women with secondary recurrent pregnancy loss (RPL)? SUMMARY ANSWER: Only consecutive early pregnancy losses after the last birth have a statistically significant negative prognostic...... impact in women with secondary RPL. WHAT IS KNOWN ALREADY: The risk of a new pregnancy loss increases with the number of previous pregnancy losses in patients with RPL. Second trimester losses seem to exhibit a stronger negative impact than early losses. It is unknown whether the sequence of pregnancy...

  4. Tuning of the Compact Linear Collider Beam Delivery System

    CERN Document Server

    Garcia, H; Inntjore Levinsen, Y; Latina, A; Tomas, R; Snuverink, J

    2014-01-01

    Tuning the Compact Linear Collider (CLIC) BeamDelivery System (BDS), and in particular the Final Focus (FF), is a challenging task. In simulations without misalignments, the goal is to reach 120%o f the nominal luminosity target, in order to allow for 10% loss due to static imperfections, and another 10% loss from dynamic imperfections. Various approaches have been considered to correct the magnet misalignments, including 1-1 correction, Dispersion Free Steering (DFS), and several minimization methods utilizing multipole movers. In this paper we report on the recent advancements towards a feasible tuning approach that reaches the required luminosity target.

  5. Specialized beam diagnostic measurements for an ADTT accelerator funnel

    International Nuclear Information System (INIS)

    Gilpatrick, John Douglas

    1995-01-01

    Los Alamos National Laboratory has proposed several CW-proton-beam facilities for accelerator-driven transmutation technologies (ADTT) with beam-current densities greater than 5 mA/mm 2 . The primary beam-diagnostics-instrumentation requirement for these facilities is to provide sufficient beam information to understand and minimize beam-loss. To accomplish this task, the beam diagnostics instrumentation must measure beam parameters such as the projected centroids and profiles, total integrated current, and particle loss. Because of the high specific energy loss in materials at beam energies less than 20 MeV, interceptive measurements such as wire scanners or fluors cannot be used to determine beam profiles or centroids. Therefore, noninterceptive techniques must be used for on-line diagnosis of high-intensity CW beam at low energies. The beam funnel area of these proposed accelerator facilities provide a particular interesting beam measurement challenge. In this area of the accelerator, beam measurements must also sense how well the two funnel input-beams are matched to each other in phase space. This paper will discuss some of the measurement requirements for these proposed accelerator facilities and the various noninterceptive techniques to measure dual-beam funnel operation

  6. Specialized beam diagnostic measurements for an ADTT accelerator funnel

    International Nuclear Information System (INIS)

    Gilpatrick, J.D.

    1995-01-01

    Los Alamos National Laboratory has proposed several CW-proton-beam facilities for accelerator-driven transmutation technologies (ADTT) with beam-current densities greater than 5 mA/mm 2 . The primary beam-diagnostics-instrumentation requirement for these facilities is to provide sufficient beam information to understand and minimize beam-loss. To accomplish this task, the beam diagnostics instrumentation must measure beam parameters such as the projected centroids and profiles, total integrated current, and particle loss. Because of the high specific energy loss in materials at beam energies less than 20 MeV, interceptive measurements such as wire scanners or fluors cannot be used to determine beam profiles or centroids. Therefore, noninterceptive techniques must be used for on-line diagnosis of high-intensity CW beam at low energies. The beam funnel area of these proposed accelerator facilities provide a particular interesting beam measurement challenge. In this area of the accelerator, beam measurements must also sense how well the two funnel-input-beams are matched to each other in phase space. This paper will discuss some of the measurement requirements for these proposed accelerator facilities and the various noninterceptive techniques to measure dual-beam funnel operation

  7. Specialized beam diagnostic measurements for an ADTT accelerator funnel

    Energy Technology Data Exchange (ETDEWEB)

    Gilpatrick, J.D.

    1995-10-01

    Los Alamos National Laboratory has proposed several CW-proton-beam facilities for accelerator-driven transmutation technologies (ADTT) with beam-current densities greater than 5 mA/mm{sup 2}. The primary beam-diagnostics-instrumentation requirement for these facilities is to provide sufficient beam information to understand and minimize beam-loss. To accomplish this task, the beam diagnostics instrumentation must measure beam parameters such as the projected centroids and profiles, total integrated current, and particle loss. Because of the high specific energy loss in materials at beam energies less than 20 MeV, interceptive measurements such as wire scanners or fluors cannot be used to determine beam profiles or centroids. Therefore, noninterceptive techniques must be used for on-line diagnosis of high-intensity CW beam at low energies. The beam funnel area of these proposed accelerator facilities provide a particular interesting beam measurement challenge. In this area of the accelerator, beam measurements must also sense how well the two funnel-input-beams are matched to each other in phase space. This paper will discuss some of the measurement requirements for these proposed accelerator facilities and the various noninterceptive techniques to measure dual-beam funnel operation.

  8. Coherent Beam-Beam Oscillations at the LHC

    CERN Document Server

    Zorzano-Mier, M P

    1999-01-01

    The transverse coherent motion of the two colliding LHC beams is studied by multi-particle tracking, where the beam-beam force is calculated assuming a Gaussian beam distribution with variable barycentres and rms beam sizes. The simulation yields the coherent and incoherent oscillation frequencies, the emittance growth of either beam, and evidence for the existence or lack of Landau damping. The transverse beam sizes change with the fractional part of the tune as expected from the dynamic beta effect. For head-on collisions, we find that the pi-mode frequency lies outside of the continuum frequency spread if the ratio of the beam-beam parameters exceeds 0.6, in accordance with predictions [1]. For smaller ratios, the pi-mode is Landau damped. When long range interactions are also included, undamped coherent modes do still exist outside the continuum, both with and without alternating crossing planes at two interaction points. However, the simulation shows that separating the tunes of the two beams can restore...

  9. Hair Loss

    Science.gov (United States)

    ... overall hair thinning and not bald patches. Full-body hair loss. Some conditions and medical treatments, such as ... in the loss of hair all over your body. The hair usually grows back. Patches of scaling that spread ...

  10. LONGITUDINAL MISMATCH IN SCL AS A SOURCE OF BEAM HALO.

    Energy Technology Data Exchange (ETDEWEB)

    RUGGIERO,A.G.

    2003-06-19

    An advantage of a proton Super-conducting Linac (SCL) is that RF cavities can be operated independently, allowing easier beam transport: and acceleration. But cavities are to be separated by drifts long enough to avoid they couple to each other. Moreover, cavities are placed in cryostats that include inactive insertions for cold-warm transitions; and interspersed are warm insertions for magnets and other devices. The SCL is then an alternating sequence of accelerating elements and drifts. No periodicity is present, and the longitudinal motion is not adiabatic. This has the consequence that the beam bunch ellipse will tumble, dilute and create a halo in the momentum plane because of inherent nonlinearities. When this is coupled to longitudinal space-charge forces, it may cause beam loss with latent activation of the accelerator components.

  11. Beam position monitor for energy recovered linac beams

    Energy Technology Data Exchange (ETDEWEB)

    Powers, Thomas; Evtushenko, Pavel

    2017-06-06

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

  12. Beam Instrumentation for the Spallation Neutron Source Ring

    International Nuclear Information System (INIS)

    Witkover, R. L.; Cameron, P. R.; Shea, T. J.; Connolly, R. C.; Kesselman, M.

    1999-01-01

    The Spallation Neutron Source (SNS) will be constructed by a multi-laboratory collaboration with BNL responsible for the transfer lines and ring. The 1 MW beam power necessitates careful monitoring to minimize un-controlled loss. This high beam power will influence the design of the monitors in the high energy beam transport line (HEBT) from linac to ring, in the ring, and in the ring-to-target transfer line (RTBT). The ring instrumentation must cover a 3-decade range of beam intensity during accumulation. Beam loss monitoring will be especially critical since un-controlled beam loss must be kept below 10 -4 . A Beam-In-Gap (BIG) monitor is being designed to assure out-of-bucket beam will not be lost in the ring

  13. Method and apparatus for laser-controlled proton beam radiology

    Science.gov (United States)

    Johnstone, Carol J.

    1998-01-01

    A proton beam radiology system provides cancer treatment and proton radiography. The system includes an accelerator for producing an H.sup.- beam and a laser source for generating a laser beam. A photodetachment module is located proximate the periphery of the accelerator. The photodetachment module combines the H.sup.- beam and laser beam to produce a neutral beam therefrom within a subsection of the H.sup.- beam. The photodetachment module emits the neutral beam along a trajectory defined by the laser beam. The photodetachment module includes a stripping foil which forms a proton beam from the neutral beam. The proton beam is delivered to a conveyance segment which transports the proton beam to a patient treatment station. The photodetachment module further includes a laser scanner which moves the laser beam along a path transverse to the cross-section of the H.sup.- beam in order to form the neutral beam in subsections of the H.sup.- beam. As the scanning laser moves across the H.sup.- beam, it similarly varies the trajectory of the proton beam emitted from the photodetachment module and in turn varies the target location of the proton beam upon the patient. Intensity modulation of the proton beam can also be achieved by controlling the output of the laser.

  14. BEAM-BEAM SIMULATIONS FOR DOUBLE-GAUSSIAN BEAMS.

    Energy Technology Data Exchange (ETDEWEB)

    MONTAG, C.; MALITSKY, N.; BEN-ZVI, I.; LITVINENKO, V.

    2005-05-16

    Electron cooling together with intra-beam scattering results in a transverse distribution that can best be described by a sum of two gaussians, one for the high-density core and one for the tails of the distribution. Simulation studies are being performed to understand the beam-beam interaction of these double-gaussian beams. Here we report the effect of low-frequency random tune modulations on diffusion in double-gaussian beams and compare the effects to those in beam-beam interactions with regular gaussian beams and identical tune shift parameters.

  15. BEAM-BEAM SIMULATIONS FOR DOUBLE-GAUSSIAN BEAMS

    International Nuclear Information System (INIS)

    MONTAG, C.; MALITSKY, N.; BEN-ZVI, I.; LITVINENKO, V.

    2005-01-01

    Electron cooling together with intra-beam scattering results in a transverse distribution that can best be described by a sum of two gaussians, one for the high-density core and one for the tails of the distribution. Simulation studies are being performed to understand the beam-beam interaction of these double-gaussian beams. Here we report the effect of loW--frequency random tune modulations on diffusion in double-gaussian beams and compare the effects to those in beam-beam interactions with regular gaussian beams and identical tune shift parameters

  16. Beam-Beam Simulations for Double-Gaussian Beams

    CERN Document Server

    Montag, Christoph; Litvinenko, Vladimir N; Malitsky, Nikolay

    2005-01-01

    Electron cooling together with intra-beam scattering results in a transverse distribution that can best be described by a sum of two Gaussians, one for the high-density core and one for the tails of the distribution. Simulation studies are being performed to understand the beam-beam interaction of these double-Gaussian beams. Here we report the effect of low-frequency random tune modulations on diffusion in double-Gaussian beams and compare the effects to those in beam-beam interactions with regular Gaussian beams and identical tuneshift parameters.

  17. A machine protection beam position monitor system

    International Nuclear Information System (INIS)

    Medvedko, E.; Smith, S.; Fisher, A.

    1998-01-01

    Loss of the stored beam in an uncontrolled manner can cause damage to the PEP-II B Factory. We describe here a device which detects large beam position excursions or unexpected beam loss and triggers the beam abort system to extract the stored beam safely. The bad-orbit abort trigger beam position monitor (BOAT BPM) generates a trigger when the beam orbit is far off the center (>20 mm), or rapid beam current loss (dI/dT) is detected. The BOAT BPM averages the input signal over one turn (136 kHz). AM demodulation is used to convert input signals at 476 MHz to baseband voltages. The detected signal goes to a filter section for suppression of the revolution frequency, then on to amplifiers, dividers, and comparators for position and current measurements and triggering. The derived current signal goes to a special filter, designed to perform dI/dT monitoring at fast, medium, and slow current loss rates. The BOAT BPM prototype test results confirm the design concepts

  18. Electron Beam Polarization Measurement Using Touschek Lifetime Technique

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Changchun; /Duke U., DFELL; Li, Jingyi; /Duke U., DFELL; Mikhailov, Stepan; /Duke U., DFELL; Popov, Victor; /Duke U., DFELL; Wu, Wenzhong; /Duke U., DFELL; Wu, Ying; /Duke U., DFELL; Chao, Alex; /SLAC; Xu, Hong-liang; /Hefei, NSRL; Zhang, Jian-feng; /Hefei, NSRL

    2012-08-24

    Electron beam loss due to intra-beam scattering, the Touschek effect, in a storage ring depends on the electron beam polarization. The polarization of an electron beam can be determined from the difference in the Touschek lifetime compared with an unpolarized beam. In this paper, we report on a systematic experimental procedure recently developed at Duke FEL laboratory to study the radiative polarization of a stored electron beam. Using this technique, we have successfully observed the radiative polarization build-up of an electron beam in the Duke storage ring, and determined the equilibrium degree of polarization and the time constant of the polarization build-up process.

  19. Particle beam fusion progress report January 1979 through June 1979

    International Nuclear Information System (INIS)

    1980-10-01

    The following chapters are included: (1) fusion target studies, (2) target experiments, (3) particle beam source development, (4) particle beam experiments, (5) pulsed power research and development, (6) pulsed fusion applications, and (7) electron beam fusion accelerator project

  20. Collimator fast failure losses for various HL-LHC configurations

    CERN Document Server

    Lari, L; Redaelli, S

    2014-01-01

    The upgrade of the Large Hadron Collider (LHC), in terms of beam intensity and energy, implies an increasing risk of severe damage in particular in case of beam losses during fast failures. For this reason, efforts were put in developing simulation tools to allow studies of asynchronous dump accidents, including realistic additional failure scenarios. The scope of these studies is to understand realistic beam loads in different collimators, in order to improve the actual LHC collimation system design, to provide feedbacks on optics design and to elaborate different mitigation actions. Simulations were set up with a modified SixTrack collimation routine able to simulate erroneous firing of a single dump kicker or the simultaneous malfunction of all the 15 kickers. In such a context, results are evaluated from the whole LHC collimation system point of view.

  1. Doppler-shifted neutral beam line shape and beam transmission

    Energy Technology Data Exchange (ETDEWEB)

    Kamperschroer, J.H.; Grisham, L.R.; Kokatnur, N.; Lagin, L.J.; Newman, R.A.; O`Connor, T.E.; Stevenson, T.N.; von Halle, A.

    1994-04-01

    Analysis of Doppler-shifted Balmer-{alpha} line emission from the TFTR neutral beam injection systems has revealed that the line shape is well approximated by the sum of two Gaussians, or, alternatively, by a Lorentzian. For the sum of two Gaussians, the broad portion of the distribution contains 40% of the beam power and has a divergence five times that of the narrow part. Assuming a narrow 1/e- divergence of 1.3{degrees} (based on fits to the beam shape on the calorimeter), the broad part has a divergence of 6.9{degrees}. The entire line shape is also well approximated by a Lorentzian with a half-maximum divergence of 0.9{degrees}. Up to now, fusion neutral beam modelers have assumed a single Gaussian velocity distribution, at the extraction plane, in each direction perpendicular to beam propagation. This predicts a beam transmission efficiency from the ion source to the calorimeter of 97%. Waterflow calorimetry data, however, yield a transmission efficiency of {approximately}75%, a value in rough agreement with predictions of the Gaussian or Lorentzian models presented here. The broad wing of the two Gaussian distribution also accurately predicts the loss in the neutralizer. An average angle of incidence for beam loss at the exit of the neutralizer is 2.2{degrees}, rather than the 4.95{degrees} subtended by the center of the ion source. This average angle of incidence, which is used in computing power densities on collimators, is shown to be a function of beam divergence.

  2. Doppler-shifted neutral beam line shape and beam transmission

    International Nuclear Information System (INIS)

    Kamperschroer, J.H.; Grisham, L.R.; Kokatnur, N.; Lagin, L.J.; Newman, R.A.; O'Connor, T.E.; Stevenson, T.N.; von Halle, A.

    1994-04-01

    Analysis of Doppler-shifted Balmer-α line emission from the TFTR neutral beam injection systems has revealed that the line shape is well approximated by the sum of two Gaussians, or, alternatively, by a Lorentzian. For the sum of two Gaussians, the broad portion of the distribution contains 40% of the beam power and has a divergence five times that of the narrow part. Assuming a narrow 1/e- divergence of 1.3 degrees (based on fits to the beam shape on the calorimeter), the broad part has a divergence of 6.9 degrees. The entire line shape is also well approximated by a Lorentzian with a half-maximum divergence of 0.9 degrees. Up to now, fusion neutral beam modelers have assumed a single Gaussian velocity distribution, at the extraction plane, in each direction perpendicular to beam propagation. This predicts a beam transmission efficiency from the ion source to the calorimeter of 97%. Waterflow calorimetry data, however, yield a transmission efficiency of ∼75%, a value in rough agreement with predictions of the Gaussian or Lorentzian models presented here. The broad wing of the two Gaussian distribution also accurately predicts the loss in the neutralizer. An average angle of incidence for beam loss at the exit of the neutralizer is 2.2 degrees, rather than the 4.95 degrees subtended by the center of the ion source. This average angle of incidence, which is used in computing power densities on collimators, is shown to be a function of beam divergence

  3. Propagation of high-current fast electron beam in a dielectric target

    International Nuclear Information System (INIS)

    Klimo, O.; Debayle, A.; Tikhonchuk, V.T.

    2006-01-01

    Complete test of publication follows. A relativistic electron beam with very high current density may be produced during the interaction of a short high intensity laser pulse with a solid target. In Fast Ignition approach to Inertial Confinement Fusion, such beam is supposed to heat a part of the precompressed DT fuel pellet to the conditions of an efficient ignition. For successful implementation of Fast Ignition understanding the propagation and energy deposition of the beam is crucial. A number of processes, mostly associated with the return current, are dissipating the energy of the beam or inhibiting its collimated transport, namely the filamentation. Weibel, two-stream or the recently proposed ionization instability. Ionization instability may develop in a solid dielectric target due to the dependence of the propagation velocity of the beam on the beam density. To study the propagation of high current electron beam in dielectric target, we use a one-dimensional relativistic electrostatic simulation code based on the Particle in Cell method. The code includes ionization processes in dielectric material and collisions of newly generated cold electrons. The current density of the relativistic electron beam used in this work is in the range 3-300 GA/cm 2 , while its length roughly corresponds to the beam, produced by a 40 fs laser pulse. Propagation of the beam in the polyethylene target is studied. The code is complemented by an analytical model, which is applicable og a wider range of beam parameters that are currently beyond our computational possibilities. When the head of the beam enters the plastic target, electric field grows rapidly in consequence of the charge separation and it starts to ionize atoms. In the maximum of the field, which is less than 10% of the atomic field, the density of new free electrons is two orders of magnitude higher than the beam density, which is enough for the current neutralization. Cold electrons are accelerated by the field

  4. Simulation of ion beam scattering in a gas stripper

    Science.gov (United States)

    Maxeiner, Sascha; Suter, Martin; Christl, Marcus; Synal, Hans-Arno

    2015-10-01

    Ion beam scattering in the gas stripper of an accelerator mass spectrometer (AMS) enlarges the beam phase space and broadens its energy distribution. As the size of the injected beam depends on the acceleration voltage through phase space compression, the stripper becomes a limiting factor of the overall system transmission especially for low energy AMS system in the sub MV region. The spatial beam broadening and collisions with the accelerator tube walls are a possible source for machine background and energy loss fluctuations influence the mass resolution and thus isotope separation. To investigate the physical processes responsible for these effects, a computer simulation approach was chosen. Monte Carlo simulation methods are applied to simulate elastic two body scattering processes in screened Coulomb potentials in a (gas) stripper and formulas are derived to correctly determine random collision parameters and free path lengths for arbitrary (and non-homogeneous) gas densities. A simple parametric form for the underlying scattering cross sections is discussed which features important scaling behaviors. An implementation of the simulation was able to correctly model the data gained with the TANDY AMS system at ETH Zurich. The experiment covered transmission measurements of uranium ions in helium and beam profile measurements after the ion beam passed through the He-stripper. Beam profiles measured up to very high stripper densities could be understood in full system simulations including the relevant ion optics. The presented model therefore simulates the fundamental physics of the interaction between an ion beam and a gas stripper reliably. It provides a powerful and flexible tool for optimizing existing AMS stripper geometries and for designing new, state of the art low energy AMS systems.

  5. Laser cooling of a magnetically guided ultra cold atom beam

    International Nuclear Information System (INIS)

    Aghajani-Talesh, Anoush

    2014-01-01

    This thesis examines two complimentary methods for the laser cooling of a magnetically guided ultra-cold atom beam. If combined, these methods could serve as a starting point for high-through put and possibly even continuous production of Bose-Einstein condensates. First, a mechanism is outlined to harvest ultra cold atoms from a magnetically guided atom beam into an optical dipole trap. A continuous loading scheme is described that dissipates the directed kinetic energy of a captured atom via deceleration by a magnetic potential barrier followed by optical pumping to the energetically lowest Zeeman sublevel. The application of this scheme to the transfer of ultra cold chromium atoms from a magnetically guided atom beam into a deep optical dipole trap is investigated via numerical simulations of the loading process. Based on the results of the theoretical studies the feasibility and the efficiency of our loading scheme, including the realisation of a suitable magnetic field configuration, are analysed. Second, experiments were conducted on the transverse laser cooling of a magnetically guided beam of ultra cold chromium atoms. Radial compression by a tapering of the guide is employed to adiabatically heat the beam. Inside the tapered section heat is extracted from the atom beam by a two-dimensional optical molasses perpendicular to it, resulting in a significant increase of atomic phase space density. A magnetic offset field is applied to prevent optical pumping to untrapped states. Our results demonstrate that by a suitable choice of the magnetic offset field, the cooling beam intensity and detuning, atom losses and longitudinal heating can be avoided. Final temperatures below 65 μK have been achieved, corresponding to an increase of phase space density in the guided beam by more than a factor of 30.

  6. A Low-cost Beam Profiler Based On Cerium-doped Silica Fibers

    Science.gov (United States)

    Potkins, David Edward; Braccini, Saverio; Nesteruk, Konrad Pawel; Carzaniga, Tommaso Stefano; Vedda, Anna; Chiodini, Norberto; Timmermans, Jacob; Melanson, Stephane; Dehnel, Morgan Patrick

    A beam profiler called the Universal Beam Monitor (UniBEaM) has been developed by D-Pace Inc. (Canada) and the Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics, University of Bern (Switzerland). The device is based on passing 100 to 600 micron cerium-doped optical fibers through a particle beam. Visible scintillation light from the sensor fibers is transmitted over distances of tens of meters to the light sensors with minimal signal loss and no susceptibility to electromagnetic fields. The probe has an insertion length of only 70 mm. The software plots the beam intensity distribution in the horizontal and vertical planes, and calculates the beam location and integrated profile area, which correlates well with total beam current. UniBEaM has a large dynamic range, operating with beam currents of ∼pA to mA, and a large range of particle kinetic energies of ∼keV to GeV, depending on the absorbed power density. Test data are presented for H- beams at 25keV for 500 μA, and H+ beams at 18MeV for 50pA to 10 μA. Maximum absorbed power density of the optical fiber before thermal damage is discussed in relation to dE/dx energy deposition as a function of particle type and kinetic energy. UniBEaM is well suited for a wide variety of beamlines including discovery science applications, radio-pharmaceutical production, hadron therapy, industrial ion beam applications including ion implantation, industrial electron beams, and ion source testing.

  7. Radioactive beams and their applications

    International Nuclear Information System (INIS)

    Rudchik, A.T.

    1992-01-01

    The proceedings contain lectures and contributed papers submitted to the second INR (Kiev's) International School on Nuclear Physics (Kiev, June 25 -July 2, 1991). The following sections were included in the Proceedings: Radioactive Beam Facilities, Application of Radioactive Beams in the Investigations of Nuclear Reactions, Exotic Nuclei and Clusters, Polarization Phenomena, Astrophysics and Others

  8. Three-beam double stimulated Raman scatterings

    Science.gov (United States)

    Cho, Minhaeng

    2018-01-01

    Two-beam stimulated Raman scattering with pump and Stokes beams is manifest in both the Raman loss of the pump beam and the Raman gain of the Stokes beam, and it has been used in various label-free bioimaging applications. Here, a three-beam stimulated Raman scattering that involves pump, Stokes, and depletion beams is considered, where two stimulated Raman gain-loss processes are deliberately made to compete with each other. It is shown that the three-beam Raman scattering process can be described by coupled differential equations for the increased numbers of Stokes and depletion beam photons. From approximate solutions of the coupled differential equations and numerical calculation results, it is shown that a highly efficient suppression of the Stokes Raman gain is possible by using an intense depletion beam whose frequency difference from that of the pump beam is identical to another acceptor Raman mode frequency. I anticipate that the present work will provide a theoretical framework for super-resolution stimulated Raman scattering microscopy.

  9. Transverse mode coupling instability of colliding beams

    Directory of Open Access Journals (Sweden)

    S. White

    2014-04-01

    Full Text Available In high brightness circular colliders, coherent and incoherent beam dynamics are dominated by beam-beam interactions. It is generally assumed that the incoherent tune spread introduced by the beam-beam interactions is sufficiently large to cure any instabilities originating from impedance. However, as the two counterrotating beams interact they can give rise to coherent dipole modes and therefore modify the coherent beam dynamics and stability conditions. In this case, coherent beam-beam effects and impedance cannot be treated independently and their interplay should be taken into account in any realistic attempt to study the beam stability of colliding beams. Due to the complexity of these physics processes, numerical simulations become an important tool for the analysis of this system. Two approaches are proposed in this paper: a fully self-consistent multiparticle tracking including particle-in-cell Poisson solver for the beam-beam interactions and a linearized model taking into account finite bunch length effects. To ensure the validity of the results a detailed benchmarking of these models was performed. It will be shown that under certain conditions coherent beam-beam dipole modes can couple with higher order headtail modes and lead to strong instabilities with characteristics similar to the classical transverse mode coupling instability originating from impedance alone. Possible cures for this instability are explored both for single bunch and multibunch interactions. Simulation results and experimental evidences of the existence of this instability at the LHC will be presented for the specific case of offset collisions.

  10. Ion beam studies

    International Nuclear Information System (INIS)

    Freeman, J.H.; Chivers, D.J.; Gard, G.A.; Temple, W.

    1977-04-01

    A description of techniques for the production of intense beams of heavy ions is given. A table of recommended operational procedures for most elements is included. The ionisation of boron is considered in some detail because of its particular importance as a dopant for ion implantation. (author)

  11. Charged particle beams

    CERN Document Server

    Humphries, Stanley

    2013-01-01

    Detailed enough for a text and sufficiently comprehensive for a reference, this volume addresses topics vital to understanding high-power accelerators and high-brightness-charged particle beams. Subjects include stochastic cooling, high-brightness injectors, and the free electron laser. Humphries provides students with the critical skills necessary for the problem-solving insights unique to collective physics problems. 1990 edition.

  12. The Colliding Beams Sequencer

    International Nuclear Information System (INIS)

    Johnson, D.E.; Johnson, R.P.

    1989-01-01

    The Colliding Beam Sequencer (CBS) is a computer program used to operate the pbar-p Collider by synchronizing the applications programs and simulating the activities of the accelerator operators during filling and storage. The Sequencer acts as a meta-program, running otherwise stand alone applications programs, to do the set-up, beam transfers, acceleration, low beta turn on, and diagnostics for the transfers and storage. The Sequencer and its operational performance will be described along with its special features which include a periodic scheduler and command logger. 14 refs., 3 figs

  13. Molecular beam epitaxy

    CERN Document Server

    Pamplin, Brian R

    1980-01-01

    Molecular Beam Epitaxy introduces the reader to the use of molecular beam epitaxy (MBE) in the generation of III-V and IV-VI compounds and alloys and describes the semiconductor and integrated optics reasons for using the technique. Topics covered include semiconductor superlattices by MBE; design considerations for MBE systems; periodic doping structure in gallium arsenide (GaAs); nonstoichiometry and carrier concentration control in MBE of compound semiconductors; and MBE techniques for IV-VI optoelectronic devices. The use of MBE to fabricate integrated optical devices and to study semicond

  14. Optical remote diagnostics of atmospheric propagating beams of ionizing radiation

    Science.gov (United States)

    Karl JR., Robert R.

    1990-03-06

    Data is obtained for use in diagnosing the characteristics of a beam of ionizing radiation, such as charged particle beams, neutral particle beams, and gamma ray beams. In one embodiment the beam is emitted through the atmosphere and produces nitrogen fluorescence during passage through air. The nitrogen fluorescence is detected along the beam path to provide an intensity from which various beam characteristics can be calculated from known tabulations. Optical detecting equipment is preferably located orthogonal to the beam path at a distance effective to include the entire beam path in the equipment field of view.

  15. Paul Collier : Balancing beams

    CERN Multimedia

    2009-01-01

    As former head of AB Operations, Paul Collier and his group were in the ‘cockpit’ for the LHC’s maiden voyage - piloting the first beam around the ring. But now, as Head of the Beams Department, he will need his feet firmly on the ground in order to balance all the beam activities at CERN. "As Department Head, I’ll have less direct contact with the machines," Collier says with a hint of regret. "I’ll still obviously be very involved, but they won’t actually let me loose in front of the keyboard anymore!" As the new Head of the BE Department, Collier will be in charge of nearly 400 people, and will oversee all the beam activities, including the preparations for the longest period of beam operation in the history of CERN. In the new organization, the BE, TE and EN Departments have been grouped together in the Accelerator and Technology Sector. "‘Partnership’ is a key word for the three departments," says Collier. "The n...

  16. Laser Beam Focus Analyser

    DEFF Research Database (Denmark)

    Nielsen, Peter Carøe; Hansen, Hans Nørgaard; Olsen, Flemming Ove

    2007-01-01

    the obtainable features in direct laser machining as well as heat affected zones in welding processes. This paper describes the development of a measuring unit capable of analysing beam shape and diameter of lasers to be used in manufacturing processes. The analyser is based on the principle of a rotating...... mechanical wire being swept through the laser beam at varying Z-heights. The reflected signal is analysed and the resulting beam profile determined. The development comprised the design of a flexible fixture capable of providing both rotation and Z-axis movement, control software including data capture...... and finally data analysis based on the ISO approach. The device was calibrated and tested on commercially available laser systems. It showed good reproducibility. It was the target to be able to measure CW lasers with a power up to 200 W, focused down to spot diameters in the range of 10µm. In order...

  17. Suppressing Transverse Beam Halo with Nonlinear Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Stephen D. [Tech-X, Boulder; Bruhwiler, David L. [Tech-X, Boulder; Abell, Dan T. [Tech-X, Boulder; Danilov, Viatcheslav [Oak Ridge; Nagaitsev, Sergei [Fermilab; Valishev, Alexander [Fermilab; Danilov, Kirill [Tech-X, Boulder; Cary, John R. [Tech-X, Boulder

    2012-05-01

    High intensity proton storage rings are central for the development of advanced neutron sources, drivers for the production of pions in neutrino factories or muon colliders, and transmutation of radioactive waste. Fractional proton loss from the beam must be very small to prevent radioac- tivation of nearby structures, but many sources of beam loss are driven by collective effects that increase with intensity. Recent theoretical work on the use of nonlinear magnetic fields to design storage rings with integrable transverse dynamics is extended here to include collective effects, with numerical results showing validity in the presence of very high beam current. Among these effects is the formation of beam halo, where particles are driven to large amplitude oscillations by coherent space charge forces. The strong variation of particle oscillation frequency with amplitude results in nonlinear decoherence that is observed to suppress transverse halo development in the case studied. We also present a necessary generalization of the Kapchinskij-Vladimirskij equilibrium distribution, which was introduced over 50 years ago for modeling linear dynamics in particle accelerators.

  18. Properties of the TRIUMF cyclotron beam

    International Nuclear Information System (INIS)

    Craddock, M.K.; Blackmore, E.W.; Dutto, G.; Kost, C.J.; Mackenzie, G.H.; Richardson, J.R.; Root, L.W.; Schmor, P.

    1975-08-01

    Eight percent of the 300 keV d.c. beam from the ion source can be transmitted to 500 MeV in the TRIUMF cyclotron, without using the buncher. The beam losses are entirely accounted for; there are no significant losses due to orbit dynamic problems during 1500 turns of acceleration. The phase history is in good agreement with predictions based on the magnetic field survey. The effect of the harmonic coils and injection parameters on beam quality has been investigated. (author)

  19. Operational Performance of LCLS Beam Instrumentation

    International Nuclear Information System (INIS)

    Loos, Henrik; Akre, R.; Brachmann, A.; Coffee, R.; Decker, F.-J.; Ding, Y.; Dowell, D.; Edstrom, S.; Emma, P.; Fisher, A.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, Ph.; Huang, Z.; Iverson, R.; Messerschmidt, M.; Miahnahri, A.; Moeller, S.; Nuhn, H.-D.; Ratner, D.

    2010-01-01

    The Linac Coherent Light Source (LCLS) X-ray FEL utilizing the last km of the SLAC linac has been operational since April 2009 and finished its first successful user run last December. The various diagnostics for electron beam properties including beam position monitors, wire scanners, beam profile monitors, and bunch length diagnostics are presented as well as diagnostics for the X-ray beam. The low emittance and ultra-short electron beam required for X-ray FEL operation has implications on the transverse and longitudinal diagnostics. The coherence effects of the beam profile monitors and the challenges of measuring fs long bunches are discussed.

  20. Operational Performance of LCLS Beam Instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Loos, Henrik; Akre, R.; Brachmann, A.; Coffee, R.; Decker, F.-J.; Ding, Y.; Dowell, D.; Edstrom, S.; Emma, P.; Fisher, A.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, Ph.; Huang, Z.; Iverson, R.; Messerschmidt, M.; Miahnahri, A.; Moeller, S.; Nuhn, H.-D.; Ratner, D.; /SLAC /LLNL, Livermore

    2010-06-15

    The Linac Coherent Light Source (LCLS) X-ray FEL utilizing the last km of the SLAC linac has been operational since April 2009 and finished its first successful user run last December. The various diagnostics for electron beam properties including beam position monitors, wire scanners, beam profile monitors, and bunch length diagnostics are presented as well as diagnostics for the X-ray beam. The low emittance and ultra-short electron beam required for X-ray FEL operation has implications on the transverse and longitudinal diagnostics. The coherence effects of the beam profile monitors and the challenges of measuring fs long bunches are discussed.

  1. Beam Position Monitor System for PEP II

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Stephen R.; Aiello, G.Roberto; Hendrickson, Linda J.; Johnson, Ronald G.; Mills, Mark R.; Olsen, Jeff J.; /SLAC

    2011-09-12

    We describe the beam position monitor system built for PEP-II, the B-factory at SLAC. The system reports beam position for bunches of between 5 x 10{sup 8} and 8 x 10{sup 10} electron charges, either singly or as continuous streams of bunches every 4.2 ns. Resolution at full charge is to be better than 10 microns in a single turn. Higher resolution is available via on-board multi-turn averaging. The position signal is processed in a 20 MHz bandwidth around 952 MHz. This bandwidth, rather broader than that typical of RF position monitors, allows good resolution for low charge single bunches. Additional novel features include stringent control of return losses in order to minimize cross-talk between nearby bunches which may contain very different charges. The digitizing electronics is multiplexed between the two PEP-II storage rings. Design, construction, and installation experience, as well as first results with beam are presented.

  2. Beam transport

    International Nuclear Information System (INIS)

    1988-01-01

    The beam diagnostic components for both the transfer and the high-energy beamlines perform well except for some of the scanners whose noise pick-up has become a problem, especially at low beam intensities. This noise pick-up is primarily due to deterioration of the bearings in the scanner. At some locations in the high-energy beamlines, scanners were replaced by harps as the scanners proved to be practically useless for the low-intensity beams required in the experimental areas. The slits in the low-energy beamline, which are not water-cooled, have to be repaired at regular intervals because of vacuum leaks. Overheating causes the ceramic feedthroughs to deteriorate resulting in the vacuum leaks. Water-cooled slits have been ordered to replace the existing slits which will later be used in the beamlines associated with the second injector cyclotron SPC2. The current-measurement system will be slightly modified and should then be much more reliable. 3 figs

  3. Nuclear physics with radioactive beams

    International Nuclear Information System (INIS)

    Bimbot, R.

    1994-01-01

    Radioactive beams can be produced through two different and complementary ways:i. the production at rest of radioactive nuclei, followed by their acceleration using conventional techniques.This method is the best for producing low energy radioactive beams. ii. the fragmentation of high energy heavy ion beams ( over 30 MeV/u), followed by the selection and purification of a given secondary beam using magnetic spectrometers. This technique leads to high energy radioactive beams. Both methods have now been used in several laboratories in the world. Examples of the corresponding experimental equipment will be presented, and especially Lise 3, Sissi, and the spiral project at GANIL. Radioactive beams have used for several purposes in nuclear physics: i. they constitute the fastest technique ever used for transferring exotic nuclei from the production point to a well shielded place where detectors can be operated for studying their properties in good conditions. At the same time, they can be identified using solid state detectors and the time-of-flight/energy-loss technique. Illustrations of the results obtained in this domain (mass and half-life measurements, recent identification of the isotope sup 1 sup 0 sup 0 Sn) is given. ii. they are used to induce nuclear reactions which may bring new information on nuclear structure. For example, the measurement of total reaction cross-sections for many radioactive projectiles revealed the existence of halo nuclei such as sup 1 sup 1 Li and sup 1 sup 1 Be. Beams of these isotopes have been extensively used to precise their structure.iii. in the domain of nuclear astrophysics, radioactive beams are used to measure, through direct or indirect methods, the cross sections for reactions of crucial interest in nucleosynthesis. Finally, radioactive beams of light positron emitters, such as sup 1 sup 9 Ne have considerable interest for medical purposes and especially in the growing field of heavy-ion radiotherapy. 8 figs., 24 refs

  4. Investigation of Generation, Acceleration, Transport and Final Focusing of High-Intensity Heavy Ion Beams from Sources to Targets

    Energy Technology Data Exchange (ETDEWEB)

    Chiping Chen

    2006-10-26

    Under the auspices of the research grant, the Intense Beam Theoretical Research Goup at Massachusetts Institute of Technology's Plasma Science and Fusion Center made significant contributions in a number of important areas in the HIF and HEDP research, including: (a) Derivation of rms envelope equations and study of rms envelope dynamics for high-intensity heavy ion beams in a small-aperture AG focusing transport systems; (b) Identification of a new mechanism for chaotic particle motion, halo formation, and beam loss in high-intensity heavy ion beams in a small-aperture AG focusing systems; Development of elliptic beam theory; (d) Study of Physics Issues in the Neutralization Transport Experiment (NTX).

  5. Investigation of Generation, Acceleration, Transport and Final Focusing of High-Intensity Heavy Ion Beams from Sources to Targets

    International Nuclear Information System (INIS)

    Chiping Chen

    2006-01-01

    Under the auspices of the research grant, the Intense Beam Theoretical Research Group at Massachusetts Institute of Technology's Plasma Science and Fusion Center made significant contributions in a number of important areas in the HIF and HEDP research, including: (a) Derivation of rms envelope equations and study of rms envelope dynamics for high-intensity heavy ion beams in a small-aperture AG focusing transport systems; (b) Identification of a new mechanism for chaotic particle motion, halo formation, and beam loss in high-intensity heavy ion beams in a small-aperture AG focusing systems; (c) Development of elliptic beam theory; and (d) Study of Physics Issues in the Neutralization Transport Experiment (NTX)

  6. Ion beam modification of solids ion-solid interaction and radiation damage

    CERN Document Server

    Wesch, Werner

    2016-01-01

    This book presents the method of ion beam modification of solids in realization, theory and applications in a comprehensive way. It provides a review of the physical basics of ion-solid interaction and on ion-beam induced structural modifications of solids. Ion beams are widely used to modify the physical properties of materials. A complete theory of ion stopping in matter and the calculation of the energy loss due to nuclear and electronic interactions are presented including the effect of ion channeling. To explain structural modifications due to high electronic excitations, different concepts are presented with special emphasis on the thermal spike model. Furthermore, general concepts of damage evolution as a function of ion mass, ion fluence, ion flux and temperature are described in detail and their limits and applicability are discussed. The effect of nuclear and electronic energy loss on structural modifications of solids such as damage formation, phase transitions and amorphization is reviewed for ins...

  7. Global Hearing Loss Prevention.

    Science.gov (United States)

    Brown, Clifford Scott; Emmett, Susan D; Robler, Samantha Kleindienst; Tucci, Debara L

    2018-03-07

    Hearing loss is the fourth leading contributor to years lived with a disability worldwide. Most recent estimates indicate that one-half of a billion people suffer from disabling hearing loss worldwide. The social and economic burden is significant. When attributing monetary value to years lived with disability owing to hearing loss, there is greater than $US750 billion lost each year globally. There are numerous contributors to hearing loss, including congenital, infectious, noise exposure, age-related, traumatic, and immune-mediated causes. Understanding the pathophysiology of these factors allows for the development of preventative and treatment strategies specific to the underlying cause. Copyright © 2018 Elsevier Inc. All rights reserved.

  8. Beam-beam synchrobetatron resonance at the LHC

    CERN Document Server

    OHMI, K

    2012-01-01

    Some beam-beam simulations are presented for the LHC beam parameters of late 2012, with collisions at nonzero crossing angle in IPs 1 and 5. Long-range encounters and other IPs are not included. Strong emittance growth is observed above 3the -rd order resonance. Synchrotron motion and z dependent beam-beam force, in particular the nonzero crossing angle, are essential ingredients for this growth. Bunch shortening is observed simultaenously with the strong transverse emittance growth, which is consistent with LHC observations in November 2012. The simulations do not show any significant growth close to the 7-th order resonance ~0.29. The simulated bunch shortening at 3Qy~1is sensitive to Qx. Open questions are if the tune of some bunches may exceed 0.33 in LHC, and/or whether electron cloud also contributes to the phenomenon. This presentation was given at CERN on 4 December 2012.

  9. Beam-Beam Simulation of Crab Cavity White Noise for LHC Upgrade

    CERN Document Server

    Qiang, J; Pieloni, Tatiana; Ohmi, Kazuhito

    2015-01-01

    High luminosity LHC upgrade will improve the luminosity of the current LHC operation by an order of magnitude. Crab cavity as a critical component for compensating luminosity loss from large crossing angle collision and also providing luminosity leveling for the LHC upgrade is being actively pursued. In this paper, we will report on the study of potential effects of the crab cavity white noise errors on the beam luminosity lifetime based on strong-strong beam-beam simulations.

  10. Upgrading the GANIL facilities for high-intensity heavy ion beams

    International Nuclear Information System (INIS)

    Baron, E.

    1995-01-01

    A new project, called THI, is underway at GANIL for taking advantage of the high intensities extracted from the 14 GHz ion source. The goal is to boost the present beam intensities by a factor of the order of 15 for light ion species up to Ar while coping with beam powers of several kW. The status of the numerous components of this upgrading is described, including non-interceptive beam diagnostics, beam loss detection, supervision of electric and magnetic supplies, thermal shielding, solutions for radiation and safety problems, movable stripper, etc. The status of a re-buncher to be placed between the two separated sector cyclotrons in order to ameliorate the extraction efficiency of the last cyclotron is also presented. (author)

  11. The NuMI neutrino beam

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, P.; Anderson, K.; Andrews, M.; Andrews, R. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Anghel, I. [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Argonne National Laboratory, Argonne, IL 60439 (United States); Augustine, D. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Aurisano, A. [Department of Physics, University of Cincinnati, Cincinnati, OH 45221 (United States); Avvakumov, S. [Department of Physics, Stanford University, Stanford, CA 94305 (United States); Ayres, D.S. [Argonne National Laboratory, Argonne, IL 60439 (United States); Baller, B. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Barish, B. [Lauritsen Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States); Barr, G. [Subdepartment of Particle Physics, University of Oxford, Oxford OX1 3RH (United Kingdom); Barrett, W.L. [Physics Department, Western Washington University, Bellingham, WA 98225 (United States); Bernstein, R.H.; Biggs, J. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Bishai, M. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Blake, A. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Bocean, V.; Bock, G.J.; Boehnlein, D.J. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); and others

    2016-01-11

    This paper describes the hardware and operations of the Neutrinos at the Main Injector (NuMI) beam at Fermilab. It elaborates on the design considerations for the beam as a whole and for individual elements. The most important design details of individual components are described. Beam monitoring systems and procedures, including the tuning and alignment of the beam and NuMI long-term performance, are also discussed.

  12. Beam divergence scaling in neutral beam injectors

    International Nuclear Information System (INIS)

    Holmes, A.J.T.

    1976-01-01

    One of the main considerations in the design of neutral beam injectors is to monimize the divergence of the primary ion beam and hence maximize the beam transport and minimize the input of thermal gas. Experimental measurements of the divergence of a cylindrical ion beam are presented and these measurements are used to analyze the major components of ion beam divergence, namely: space charge expansion, gas-ion scattering, emittance and optical aberrations. The implication of these divergence components in the design of a neutral beam injector system is discussed and a method of maximizing the beam current is described for a given area of source plasma

  13. Handbook on loss reserving

    CERN Document Server

    Schmidt, Klaus; Schnaus, Anja

    2016-01-01

    This handbook presents the basic aspects of actuarial loss reserving. Besides the traditional methods, it also includes a description of more recent ones and a discussion of certain problems occurring in actuarial practice, like inflation, scarce data, large claims, slow loss development, the use of market statistics, the need for simulation techniques and the task of calculating best estimates and ranges of future losses. In property and casualty insurance the provisions for payment obligations from losses that have occurred but have not yet been settled usually constitute the largest item on the liabilities side of an insurer's balance sheet. For this reason, the determination and evaluation of these loss reserves is of considerable economic importance for every property and casualty insurer. Actuarial students, academics as well as practicing actuaries will benefit from this overview of the most important actuarial methods of loss reserving by developing an understanding of the underlying stochastic models...

  14. Loss of chance: what loss?

    Science.gov (United States)

    Bird, Sara

    2006-05-01

    A recent New South Wales judgment, Rufo v Hosking, explored the concept of 'loss of a chance' in medical negligence claims. 'Loss of a chance' claims involve an allegation that the patient lost the chance of a better outcome as a result of the negligence of the medical practitioner. This article outlines the case and discusses the implications of the judgment for medical practitioners.

  15. The ELENA Beam Diagnostics Systems

    CERN Document Server

    Tranquille, G

    2013-01-01

    The Extra Low ENergy Antiproton ring (ELENA) to be built at CERN is aimed at substantially increasing the number of antiprotons to the low energy antiproton physics community. It will be a small machine which will decelerate low intensity beams (<4x107) from 5.3 MeV to 100 keV and will be equipped with an electron cooler to avoid beam losses during the deceleration and to significantly reduce beam phase space at extraction. To measure the beam parameters from the extraction point of the Antiproton Decelerator (AD), through the ELENA ring and all the way to the experiments, many systems will be needed to ensure that the desired beam characteristics are obtained. Particular attention needs to be paid to the performance of the electron cooler which depends on reliable instrumentation in order to efficiently cool the antiprotons. This contribution will present the different monitors that have been proposed to measure the various beam parameters as well as some of the developments going on to further improve th...

  16. BEAM TRANSPORT LINES FOR THE BSNS.

    Energy Technology Data Exchange (ETDEWEB)

    WEI, J.

    2006-06-26

    This paper presents the design of two beam transport lines at the BSNS: one is the injection line from the Linac to the RCS and the other is the target line from the RCS to the target station. In the injection beam line, space charge effects, transverse halo collimation, momentum tail collimation and debunching are the main concerned topics. A new method of using triplet cells and stripping foils is used to collimate transverse halo. A long straight section is reserved for the future upgrading linac and debuncher. In the target beam line, large halo emittance, beam stability at the target due to kicker failures and beam jitters, shielding of back-scattering neutrons from the target are main concerned topics. Special bi-gap magnets will be used to reduce beam losses in the collimators in front of the target.

  17. Beam screens for the LHC beam pipes

    CERN Multimedia

    Patrice Loïez

    1997-01-01

    Cross-section of LHC prototype beam pipes showing the beam screens. Slits in the screens allow residual gas molecules to be pumped out and become frozen to the walls of the ultra-cold beam pipe. Beam screens like these have been designed to line the beam pipes, absorbing radiation before it can hit the magnets and warm them up, an effect that would greatly reduce the magnetic field and cause serious damage.

  18. Beam geometry selection using sequential beam addition.

    Science.gov (United States)

    Popple, Richard A; Brezovich, Ivan A; Fiveash, John B

    2014-05-01

    The selection of optimal beam geometry has been of interest since the inception of conformal radiotherapy. The authors report on sequential beam addition, a simple beam geometry selection method, for intensity modulated radiation therapy. The sequential beam addition algorithm (SBA) requires definition of an objective function (score) and a set of candidate beam geometries (pool). In the first iteration, the optimal score is determined for each beam in the pool and the beam with the best score selected. In the next iteration, the optimal score is calculated for each beam remaining in the pool combined with the beam selected in the first iteration, and the best scoring beam is selected. The process is repeated until the desired number of beams is reached. The authors selected three treatment sites, breast, lung, and brain, and determined beam arrangements for up to 11 beams from a pool comprised of 25 equiangular transverse beams. For the brain, arrangements were additionally selected from a pool of 22 noncoplanar beams. Scores were determined for geometries comprised equiangular transverse beams (EQA), as well as two tangential beams for the breast case. In all cases, SBA resulted in scores superior to EQA. The breast case had the strongest dependence on beam geometry, for which only the 7-beam EQA geometry had a score better than the two tangential beams, whereas all SBA geometries with more than two beams were superior. In the lung case, EQA and SBA scores monotonically improved with increasing number of beams; however, SBA required fewer beams to achieve scores equivalent to EQA. For the brain case, SBA with a coplanar pool was equivalent to EQA, while the noncoplanar pool resulted in slightly better scores; however, the dose-volume histograms demonstrated that the differences were not clinically significant. For situations in which beam geometry has a significant effect on the objective function, SBA can identify arrangements equivalent to equiangular

  19. Beam geometry selection using sequential beam addition

    Energy Technology Data Exchange (ETDEWEB)

    Popple, Richard A., E-mail: rpopple@uabmc.edu; Brezovich, Ivan A.; Fiveash, John B. [Department of Radiation Oncology, The University of Alabama at Birmingham, 1720 2nd Avenue South, Birmingham, Alabama 35294 (United States)

    2014-05-15

    Purpose: The selection of optimal beam geometry has been of interest since the inception of conformal radiotherapy. The authors report on sequential beam addition, a simple beam geometry selection method, for intensity modulated radiation therapy. Methods: The sequential beam addition algorithm (SBA) requires definition of an objective function (score) and a set of candidate beam geometries (pool). In the first iteration, the optimal score is determined for each beam in the pool and the beam with the best score selected. In the next iteration, the optimal score is calculated for each beam remaining in the pool combined with the beam selected in the first iteration, and the best scoring beam is selected. The process is repeated until the desired number of beams is reached. The authors selected three treatment sites, breast, lung, and brain, and determined beam arrangements for up to 11 beams from a pool comprised of 25 equiangular transverse beams. For the brain, arrangements were additionally selected from a pool of 22 noncoplanar beams. Scores were determined for geometries comprised equiangular transverse beams (EQA), as well as two tangential beams for the breast case. Results: In all cases, SBA resulted in scores superior to EQA. The breast case had the strongest dependence on beam geometry, for which only the 7-beam EQA geometry had a score better than the two tangential beams, whereas all SBA geometries with more than two beams were superior. In the lung case, EQA and SBA scores monotonically improved with increasing number of beams; however, SBA required fewer beams to achieve scores equivalent to EQA. For the brain case, SBA with a coplanar pool was equivalent to EQA, while the noncoplanar pool resulted in slightly better scores; however, the dose-volume histograms demonstrated that the differences were not clinically significant. Conclusions: For situations in which beam geometry has a significant effect on the objective function, SBA can identify

  20. Hair Loss

    Science.gov (United States)

    ... and Nutrition Healthy Food Choices Weight Loss and Diet Plans Nutrients and Nutritional Info Sugar and Sugar Substitutes Exercise and Fitness Exercise Basics Sports Safety Injury Rehabilitation Emotional Well-Being Mental Health ...

  1. Memory loss

    Science.gov (United States)

    A person with memory loss needs a lot of support. It helps to show the person familiar objects, music, or and photos or play familiar music. Write down when the person should take any medicine or do other ...

  2. Hair Loss

    Science.gov (United States)

    ... hair bulb. This is where the hair's color pigment, or melanin, is produced. Most people lose about ... diabetes or thyroid disease , can interfere with hair production and cause hair loss. People with lupus can ...

  3. Beam Instrumentation Global Network [BIGNET]: a common web portal for Beam instrumentalists

    CERN Document Server

    Gras, J-J

    2012-01-01

    This document will present an initiative launched during the International Particle Accelerator Conference (IPAC11) to define and produce a common web portal for Beam Instrumentation, with the aim of allowing any beam instrumentalist to easily and efficiently: - find the laboratories with machines using beams of similar characteristics (particle type, total beam intensity, bunch intensity, frequency, energy) - find the person who is working there on the beam observable concerned (i.e. beam position, loss, intensity, transverse or longitudinal profile, tune) and how to contact him/her - create discussion forums with the right audience on hot beam instrumentation topics or issues - advertise topical events and workshop - provide links towards documents describing system designs and performance assessments... This document will cover the status and prospects of the project with the aim to invite and welcome new laboratories to join the adventure.

  4. Numerical investigation of beam halo from beam gas scattering in KEK-ATF

    Science.gov (United States)

    Yang, R.; Bambade, P.; Kubo, K.; Okugi, T.; Terunuma, N.; Zhou, D.

    2017-07-01

    To demonstrate the final focus schemes of the Future Linear Collider (FLC), the Accelerator Test Facility 2 (ATF2) at KEK is devoted to focus the beam to a RMS size of a few tens of nanometers (nm) vertically and to provide stability at the nm level at the virtual Interaction Point (IP). However, the loss of halo particles upstream will introduce background to the diagnostic instrument measuring the ultra-small beam, using a laser interferometer monitor. To help the realization of the above goals and beam operation, understanding and mitigation of beam halo are crucial. In this paper, we present the systematical simulation of beam halo formation from beam gas Coulomb scattering (BGS) in the ATF damping ring. The behavior of beam halo with various machine parameters is also discussed.

  5. End-of-Fill Diffusion and Halo Population Measurements with Physics Beams at 6.5 TeV

    CERN Document Server

    Valentino, Gianluca; Gorzawski, Arkadiusz; Redaelli, Stefano; Trad, Georges; Wagner, Joschka; Xu, Chen; CERN. Geneva. ATS Department

    2017-01-01

    Beam halo measurements at 6.5 TeV in the LHC were conducted with a full physics beam via collimator scrapings in end-of-fill MDs carried out in May and July 2016. From the time evolution of the beam losses in a collimator scan, it is possible to extract information on the halo diffusion and population. In the first MD, six scans were performed with two collimators in the vertical and horizontal planes in B1 and B2 respectively. The scans were done with squeezed colliding beams, with and without a gentle continuous transverse blow-up with the ADT (transverse damper) on a non-colliding bunch train. In the second MD, four scans were performed with the same collimators with squeezed colliding beams. The beam losses observed with the standard ionization chamber BLMs are compared to the diamond BLMs, and parametric fits of the diffusion model are applied to temporal loss patterns from colliding and non-colliding bunch trains. The results presented in this note also include the particle escape times and frequency an...

  6. Initial commissioning results from the APS loss monitor system

    International Nuclear Information System (INIS)

    Patterson, D.R.

    1996-01-01

    The design of the beam loss monitor system for the Argonne National Laboratory Advanced Photon Source is based on using a number of air dielectric coaxial cables as long ionization chambers. Results to date show that the loss monitor is useful in helping to determine the cause of injection losses and losses large enough to limit circulating currents in the storage ring to short lifetimes. Sensitivities ranging from 13 to 240 pC of charge collected in the injector BTS (booster-to-storage-ring) loss monitor per picocoulomb of loss have been measured, depending on the loss location. These results have been used to predict that the storage ring loss monitor leakage current limit of 10 pA per cable should allow detection of losses resulting in beam lifetimes of 100 hours or less with 100 mA stored beam. Significant DC bias levels associated with the presence of stored beam have been observed. These large bias levels are most likely caused by the loss monitor responding to hard x-ray synchrotron radiation. No such response to synchrotron radiation was observed during earlier tests at SSRL. However, the loss monitor response to average stored beam current in APS has provided a reasonable alternative to the DC current transformer (DCCT) for measuring beam lifetimes

  7. Intense nonrelativistic cesium ion beam

    International Nuclear Information System (INIS)

    Lampel, M.C.

    1984-01-01

    The Heavy Ion Fusion group at Lawrence Berkeley Laboratory has constructed the One Ampere Cesium injector as a proof of principle source to supply an induction linac with a high charge density and high brightness ion beam. This is studied here. An electron beam probe was developed as the major diagnostic tool for characterizing ion beam space charge. Electron beam probe data inversion is accomplished with the EBEAM code and a parametrically adjusted model radial charge distribution. The longitudinal charge distribution was not derived, although it is possible to do so. The radial charge distribution that is derived reveals an unexpected halo of trapped electrons surrounding the ion beam. A charge fluid theory of the effect of finite electron temperature on the focusing of neutralized ion beams (Nucl Fus. 21, 529(1981)) is applied to the problem of the cesium beam final focus at the end of the injector. It is shown that the theory's predictions and assumptions are consistent with the experimental data, and that it accounts for the observed ion beam radius of approx.5 cm and the electron halo, including the determination of an electron Debye length of approx.10 cm

  8. Stable beams

    CERN Multimedia

    2015-01-01

    Stable beams: two simple words that carry so much meaning at CERN. When LHC page one switched from "squeeze" to "stable beams" at 10.40 a.m. on Wednesday, 3 June, it triggered scenes of jubilation in control rooms around the CERN sites, as the LHC experiments started to record physics data for the first time in 27 months. This is what CERN is here for, and it’s great to be back in business after such a long period of preparation for the next stage in the LHC adventure.   I’ve said it before, but I’ll say it again. This was a great achievement, and testimony to the hard and dedicated work of so many people in the global CERN community. I could start to list the teams that have contributed, but that would be a mistake. Instead, I’d simply like to say that an achievement as impressive as running the LHC – a machine of superlatives in every respect – takes the combined effort and enthusiasm of everyone ...

  9. Transmission of the Neutral Beam Heating Beams at TJ-II

    International Nuclear Information System (INIS)

    Fuentes Lopez, C.

    2007-01-01

    Neutral beam injection heating has been development for the TJ-II stellarator. The beam has a port-through power between 700-1500 kW and injection energy 40 keV. The sensibility of the injection system to the changes of several parameters is analysed. Beam transmission is limited by losses processes since beam is born into the ions source until is coming into the fusion machine. For the beam transmission optimization several beam diagnostics have been developed. A carbon fiber composite (CFC) target calorimeter has been installed at TJ-II to study in situ the power density distribution of the neutral beams. The thermographic print of the beam can be recorded and analysed in a reliable way due to the highly anisotropic thermal conductivity of the target material. With the combined thermographic and calorimetric measurements it has been possible to determine the power density distribution of the beam. It has been found that a large beam halo is present, which can be explained by the extreme misalignment of the grids. This kind of halo has a deleterious effect on beam transport and must be minimized in order to improve the plasma heating capability of the beams. (Author) 155 refs

  10. Beam Diagnostics for the BNL Energy Recovery Linac Test Facility

    International Nuclear Information System (INIS)

    Cameron, Peter; Ben-Zvi, Ilan; Blaskiewicz, Michael; Brennan, Michael; Connolly, Roger; Dawson, William; Degen, Chris; DellaPenna, Al; Gassner, David; Kesselman, Martin; Kewish, Jorg; Litvinenko, Vladimir; Mead, Joseph; Oerter, Brian; Russo, Tom; Vetter, Kurt; Yakimenko, Vitaly

    2004-01-01

    An Energy Recovery Linac (ERL) test facility is presently under construction at BNL. The goals of this test facility are first to demonstrate stable intense CW electron beam with parameters typical for the RHIC e-cooling project (and potentially for eRHIC), second to test novel elements of the ERL (high current CW photo-cathode, superconducting RF cavity with HOM dampers, and feedback systems), and finally to test lattice dependence of stability criteria. Planned diagnostics include position monitors, loss monitors, transverse profile monitors (both optical and wires), scrapers/halo monitors, a high resolution differential current monitor, phase monitors, an energy spread monitor, and a fast transverse monitor (for beam break-up studies and the energy feedback system). We discuss diagnostics challenges that are unique to this project, and present preliminary system specifications. In addition, we include a brief discussion of the timing system

  11. Ultra-High Density Electron Beams for Beam Radiation and Beam Plasma Interaction

    CERN Document Server

    Anderson, Scott; Frigola, Pedro; Gibson, David J; Hartemann, Fred V; Jacob, Jeremy S; Lim, Jae; Musumeci, Pietro; Rosenzweig, James E; Travish, Gil; Tremaine, Aaron M

    2005-01-01

    Current and future applications of high brightness electron beams, which include advanced accelerators such as the plasma wake-field accelerator (PWFA) and beam-radiation interactions such as inverse-Compton scattering (ICS), require both transverse and longitudinal beam sizes on the order of tens of microns. Ultra-high density beams may be produced at moderate energy (50 MeV) by compression and subsequent strong focusing of low emittance, photoinjector sources. We describe the implementation of this method used at LLNL's PLEIADES ICS x-ray source in which the photoinjector-generated beam has been compressed to 300 fsec duration using the velocity bunching technique and focused to 20 μm rms size using an extremely high gradient, permanent magnet quadrupole (PMQ) focusing system.

  12. LHC Report: Beam on

    CERN Multimedia

    Rossano Giachino for the LHC Team

    2012-01-01

    The powering tests described in the last edition of the Bulletin were successfully finished at the end of the first week of March opening the way for 4 TeV operations this year. The beam was back in the machine on Wednesday 14 March. The first collisions at 4 TeV are scheduled for the first week of April.   The first beam of 2012 is dumped after making a few rounds in the LHC. The magnet powering tests were followed by the machine checkout phase. Here the operations team in collaboration with the equipment groups performs a sequence of tests to ensure the readiness of the LHC for beam. The tests include driving all the LHC systems – beam dump, injection, collimation, RF, power converters, magnet circuits, vacuum, interlocks, controls, timing and synchronization – through the operational cycle. The “checkout phase” is really a massive de-bugging exercise, which is performed with the objective of ensuring the proper functioning of the whole machine and t...

  13. Study of longitudinal dynamics in space-charge dominated beams

    Science.gov (United States)

    Tian, Kai

    from the 6-D phase space measurement has been used as initial conditions in computer simulations in order to explore the cause of discrepancies we have observed earlier between the experimental and theoretical models. After extensive simulation studies, we find that the beam loss inside the perturbation due to mismatch or misalignment is an important factor that needs to be included in the models for better reliability.

  14. Beam imaging sensor and method for using same

    Science.gov (United States)

    McAninch, Michael D.; Root, Jeffrey J.

    2017-01-03

    The present invention relates generally to the field of sensors for beam imaging and, in particular, to a new and useful beam imaging sensor for use in determining, for example, the power density distribution of a beam including, but not limited to, an electron beam or an ion beam. In one embodiment, the beam imaging sensor of the present invention comprises, among other items, a circumferential slit that is either circular, elliptical or polygonal in nature. In another embodiment, the beam imaging sensor of the present invention comprises, among other things, a discontinuous partially circumferential slit. Also disclosed is a method for using the various beams sensor embodiments of the present invention.

  15. Simulations of coherent beam-beam modes at the Large Hadron Collider

    CERN Document Server

    Zorzano-Mier, M P

    2000-01-01

    The transverse coherent motion of two colliding proton beams at the Large Hadron Collider is studied by multiparticle tracking. We use the beam-beam force for a Gaussian beam distribution with variable barycenters and rms beam sizes, and optionally include the effect of long-range collisions and external impedance. The simulation yields the coherent and incoherent oscillation frequencies, the emittance growth of either beam, and evidence for the existence or lack of Landau damping. For head-on collisions of beams with equal sizes, we find that the pi -mode frequency lies outside of the continuum frequency spread, if the ratio of the beam-beam parameters exceeds 0.6, in accordance with predictions. For smaller ratios of the beam- beam parameters, or if, for equal beam-beam parameters, the beam sizes are widely different, the pi mode is Landau damped. When long- range collisions are also included, undamped coherent modes do still exist outside the continuum, both with and without alternating crossing planes at ...

  16. Heavy ion beam probing

    Energy Technology Data Exchange (ETDEWEB)

    Hickok, R L

    1980-07-01

    This report consists of the notes distributed to the participants at the IEEE Mini-Course on Modern Plasma Diagnostics that was held in Madison, Wisconsin in May 1980. It presents an overview of Heavy Ion Beam Probing that briefly describes the principles and discuss the types of measurements that can be made. The problems associated with implementing beam probes are noted, possible variations are described, estimated costs of present day systems, and the scaling requirements for large plasma devices are presented. The final chapter illustrates typical results that have been obtained on a variety of plasma devices. No detailed calculations are included in the report, but a list of references that will provide more detailed information is included.

  17. Heavy ion beam probing

    International Nuclear Information System (INIS)

    Hickok, R.L.

    1980-07-01

    This report consists of the notes distributed to the participants at the IEEE Mini-Course on Modern Plasma Diagnostics that was held in Madison, Wisconsin in May 1980. It presents an overview of Heavy Ion Beam Probing that briefly describes the principles and discuss the types of measurements that can be made. The problems associated with implementing beam probes are noted, possible variations are described, estimated costs of present day systems, and the scaling requirements for large plasma devices are presented. The final chapter illustrates typical results that have been obtained on a variety of plasma devices. No detailed calculations are included in the report, but a list of references that will provide more detailed information is included

  18. Beam Cleaning and Collimation Systems

    CERN Document Server

    Redaelli, S

    2016-01-01

    Collimation systems in particle accelerators are designed to dispose of unavoidable losses safely and efficiently during beam operation. Different roles are required for different types of accelerator. The present state of the art in beam collimation is exemplified in high-intensity, high-energy superconducting hadron colliders, like the CERN Large Hadron Collider (LHC), where stored beam energies reach levels up to several orders of magnitude higher than the tiny energies required to quench cold magnets. Collimation systems are essential systems for the daily operation of these modern machines. In this document, the design of a multistage collimation system is reviewed, taking the LHC as an example case study. In this case, unprecedented cleaning performance has been achieved, together with a system complexity comparable to no other accelerator. Aspects related to collimator design and operational challenges of large collimation systems are also addressed.

  19. Fast ion loss diagnostic plans for NSTX

    International Nuclear Information System (INIS)

    Darrow, D. S.; Bell, R.; Johnson, R.; Kugel, H.; Wilson, J. R.; Cecil, F. E.; Maingi, R.; Krasilnikov, A.; Alekseyev, A.

    2000-01-01

    The prompt loss of neutral beam ions from the National Spherical Torus Experiment (NSTX) is expected to be between 12% and 42% of the total 5 MW of beam power. There may, in addition, be losses of fast ions arising from high harmonic fast wave (HHFW) heating. Most of the lost ions will strike the HHFW antenna or the neutral beam dump. To measure these losses in the 2000 experimental campaign, thermocouples in the antenna, several infrared camera views, and a Faraday cup lost ion probe will be employed. The probe will measure loss of fast ions with E > 1 keV at three radial locations, giving the scrape-off length of the fast ions

  20. Relativistic electron beam device

    Science.gov (United States)

    Freeman, J.R.; Poukey, J.W.; Shope, S.L.; Yonas, G.

    1975-07-01

    A design is given for an electron beam device for irradiating spherical hydrogen isotope bearing targets. The accelerator, which includes hollow cathodes facing each other, injects an anode plasma between the cathodes and produces an approximately 10 nanosecond, megajoule pulse between the anode plasma and the cathodes. Targets may be repetitively positioned within the plasma between the cathodes, and accelerator diode arrangement permits materials to survive operation in a fusion power source. (auth)

  1. Lessons in beam diagnostics

    International Nuclear Information System (INIS)

    Jones, O.R.

    2012-01-01

    This paper will concentrate on the studies carried out on LHC beam instrumentation systems during the 2011 run, the improvements made and the outlook for 2012. It will include an update on the issues resolved since 2010, such as the performance of the BCT systems, and discuss advances in the bunch by bunch measurement capability of many systems. The paper will also highlight what can be hoped for in terms of performance for 2012 and the issues which remain to be solved. (author)

  2. Use of beam deflection to control an electron beam wire deposition process

    Science.gov (United States)

    Taminger, Karen M. (Inventor); Hofmeister, William H. (Inventor); Hafley, Robert A. (Inventor)

    2013-01-01

    A method for controlling an electron beam process wherein a wire is melted and deposited on a substrate as a molten pool comprises generating the electron beam with a complex raster pattern, and directing the beam onto an outer surface of the wire to thereby control a location of the wire with respect to the molten pool. Directing the beam selectively heats the outer surface of the wire and maintains the position of the wire with respect to the molten pool. An apparatus for controlling an electron beam process includes a beam gun adapted for generating the electron beam, and a controller adapted for providing the electron beam with a complex raster pattern and for directing the electron beam onto an outer surface of the wire to control a location of the wire with respect to the molten pool.

  3. Crystalline beams

    International Nuclear Information System (INIS)

    Schiffer, J.P.

    1989-01-01

    Ions in a storage ring are confined to a mean orbit by focusing elements. To a first approximation these may be described by a constant harmonic restoring force: F = -Kr. If the particles in the frame moving along with the beam have small random thermal energies, then they will occupy a cylindrical volume around the mean orbit and the focusing force will be balanced by that from the mutual repulsion of the particles. Inside the cylinder only residual two-particle interactions will play a significant role and some form of ordering might be expected to take place. The results of some of the first MD calculations showed a surprising result: not only were the particles arranged in the form of a tube, but they formed well-defined layers: concentric shells, with the particles in each shell arranged in a hexagonal lattice that is characteristic of two-dimensional Coulomb systems. This paper discusses the condense layer structure

  4. Use of radial self-field geometry for intense pulsed ion beam generation above 6 MeV on Hermes III.

    Energy Technology Data Exchange (ETDEWEB)

    Renk, Timothy Jerome [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Harper-Slaboszewicz, Victor Jozef [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ginn, William Craig [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mikkelson, Kenneth A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schall, Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cooper, Gary Wayne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2012-12-01

    We investigate the generation and propagation of intense pulsed ion beams at the 6 MeV level and above using the Hermes III facility at Sandia National Laboratories. While high-power ion beams have previously been produced using Hermes III, we have conducted systematic studies of several ion diode geometries for the purpose of maximizing focused ion energy for a number of applications. A self-field axial-gap diode of the pinch reflex type and operated in positive polarity yielded beam power below predicted levels. This is ascribed both to power flow losses of unknown origin upstream of the diode load in Hermes positive polarity operation, and to anomalies in beam focusing in this configuration. A change to a radial self-field geometry and negative polarity operation resulted in greatly increased beam voltage (> 6 MeV) and estimated ion current. A comprehensive diagnostic set was developed to characterize beam performance, including both time-dependent and time-integrated measurements of local and total beam power. A substantial high-energy ion population was identified propagating in reverse direction, i.e. from the back side of the anode in the electron beam dump. While significant progress was made in increasing beam power, further improvements in assessing the beam focusing envelope will be required before ultimate ion generation efficiency with this geometry can be completely determined.

  5. CEBAF beam viewer imaging software

    International Nuclear Information System (INIS)

    Bowling, B.A.; McDowell, C.

    1993-01-01

    This paper discusses the various software used in the analysis of beam viewer images at CEBAF. This software, developed at CEBAF, includes a three-dimensional viewscreen calibration code which takes into account such factors as multiple camera/viewscreen rotations and perspective imaging, and maintaining a calibration database for each unit. Additional software allows single-button beam spot detection, with determination of beam location, width, and quality, in less than three seconds. Software has also been implemented to assist in the determination of proper chopper RF control parameters from digitized chopper circles, providing excellent results

  6. Online diagnoses of high current-density beams

    International Nuclear Information System (INIS)

    Gilpatrick, J.D.

    1994-01-01

    Los Alamos National Laboratory has proposed several CW-proton-beam facilities for production of tritium or transmutation of nuclear waste with beam-current densities greater than 5 mA/mm 2 . The primary beam-diagnostics-instrumentation requirement for these facilities is provision of sufficient beam information to understand and minimize beam-loss. To accomplish this task, the beam-diagnostics instrumentation must measure beam parameters such as the centroids and profiles, total integrated current, and particle loss. Noninterceptive techniques must be used for diagnosis of high-intensity CW beam at low energies due to the large quantity of power deposited in an interceptive diagnostic device by the beam. Transverse and longitudinal centroid measurements have been developed for bunched beams by measuring and processing image currents on the accelerator walls. Transverse beam-profile measurement-techniques have also been developed using the interaction of the particle beam with the background gases near the beam region. This paper will discuss these noninterceptive diagnostic Techniques

  7. Composite Beam Theory with Material Nonlinearities and Progressive Damage

    Science.gov (United States)

    Jiang, Fang

    functions, and the 3D spatial gradients of these warping functions. Asymptotic analysis of the extended Hamiltonian's principle suggests dropping the terms of axial gradients of the warping functions. As a result, the solid mechanics problem resolved into a 3D continuum is dimensionally reduced to a problem of solving the warping functions on a 2D cross-sectional field by minimizing the information loss. The present theory is implemented using the finite element method (FEM) in Variational Asymptotic Beam Sectional Analysis (VABS), a general-purpose cross-sectional analysis tool. An iterative method is applied to solve the finite warping field for the classical-type model in the form of the Euler-Bernoulli beam theory. The deformation gradient tensor is directly used to enable the capability of dealing with finite deformation, various strain definitions, and several types of material constitutive laws regarding the nonlinear elasticity and progressive damage. Analytical and numerical examples are given for various problems including the trapeze effect, Poynting effect, Brazier effect, extension-bending coupling effect, and free edge damage. By comparison with the predictions from 3D finite element analyses (FEA), 2D FEA based on plane stress assumptions, and experimental data, the structural and material responses are proven to be rigorously captured by the present theory and the computational cost is significantly reduced. Due to the semi-analytical feature of the code developed, the unrealistic numerical issues widely seen in the conventional FEA with strain softening material behaviors are prevented by VABS. In light of these intrinsic features, the nonlinear elastic and inelastic 3D material models can be economically calibrated by data-matching the VABS predictions directly with the experimental measurements from slender coupons. Furthermore, the global behavior of slender composite structures in meters can also be effectively characterized by VABS without unnecessary

  8. W-Band Sheet Beam Klystron Design

    International Nuclear Information System (INIS)

    Scheitrum, G.; Caryotakis, G.; Burke, A.; Jensen, A.; Jongewaard, E.; Krasnykh, A.; Neubauer, M.; Phillips, R.; Rauenbuehler, K.

    2011-01-01

    Sheet beam devices provide important advantages for very high power, narrow bandwidth RF sources like accelerator klystrons (1). Reduced current density and increased surface area result in increased power capabi1ity, reduced magnetic fields for focusing and reduced cathode loading. These advantages are offset by increased complexity, beam formation and transport issues and potential for mode competition in the ovennoded cavities and drift tube. This paper will describe the design issues encountered in developing a 100 kW peak and 2 kW average power sheet beam k1ystron at W-band including beam formation, beam transport, circuit design, circuit fabrication and mode competition.

  9. Ion beam analysis fundamentals and applications

    CERN Document Server

    Nastasi, Michael; Wang, Yongqiang

    2015-01-01

    Ion Beam Analysis: Fundamentals and Applications explains the basic characteristics of ion beams as applied to the analysis of materials, as well as ion beam analysis (IBA) of art/archaeological objects. It focuses on the fundamentals and applications of ion beam methods of materials characterization.The book explains how ions interact with solids and describes what information can be gained. It starts by covering the fundamentals of ion beam analysis, including kinematics, ion stopping, Rutherford backscattering, channeling, elastic recoil detection, particle induced x-ray emission, and nucle

  10. LHC Beam Diagnostics - the Users Point of View

    CERN Document Server

    Wenninger, J

    2011-01-01

    The LHC started up with beam in November 2009, and within less then on year its luminosity reached 2·1032 cm-2s−1 at 3.5 TeV in October 2010. A few weeks later, in November 2010, lead ion collisions were established within little over 2 days. The fast progress and successes of the LHC commissioning and early operation would not have been possible without the excellent performance of its beam instrumentation. All essential instruments worked from the first day or were commissioned in a very short time, providing rapid diagnostics for the beam parameters. Tune and orbit feedbacks that rely on high quality measurements were used early on to achieve smooth operation with minimal beam losses. This presentation will address the performance of the LHC beam instrumentation, in particular the very large beam position and beam loss monitoring systems, both composed of many thousand channels. Present limitations and future improvements will also be discussed.

  11. Beam diffusion measurements using collimator scans in the LHC

    Science.gov (United States)

    Valentino, Gianluca; Aßmann, Ralph; Bruce, Roderik; Burkart, Florian; Previtali, Valentina; Redaelli, Stefano; Salvachua, Belen; Stancari, Giulio; Valishev, Alexander

    2013-02-01

    The time evolution of beam losses during a collimator scan provides information on halo diffusion and population. This is an essential input for machine performance characterization and for the design of collimation systems. Beam halo measurements in the CERN Large Hadron Collider were conducted through collimator scrapings in a dedicated beam study for the first time at 4 TeV. Four scans were performed with two collimators, in the vertical plane for beam 1 and horizontally for beam 2, before and after bringing the beams into collisions. Inward and outward steps were performed. A diffusion model was used to interpret the observed loss rate evolution in response to the collimator steps. With this technique, diffusion coefficients were estimated as a function of betatron oscillation amplitude from approximately 3 to 7 standard deviations of the transverse beam distribution. A comparison of halo diffusion and core emittance growth rates is also presented.

  12. Beam diffusion measurements using collimator scans in the LHC

    Directory of Open Access Journals (Sweden)

    Gianluca Valentino

    2013-02-01

    Full Text Available The time evolution of beam losses during a collimator scan provides information on halo diffusion and population. This is an essential input for machine performance characterization and for the design of collimation systems. Beam halo measurements in the CERN Large Hadron Collider were conducted through collimator scrapings in a dedicated beam study for the first time at 4 TeV. Four scans were performed with two collimators, in the vertical plane for beam 1 and horizontally for beam 2, before and after bringing the beams into collisions. Inward and outward steps were performed. A diffusion model was used to interpret the observed loss rate evolution in response to the collimator steps. With this technique, diffusion coefficients were estimated as a function of betatron oscillation amplitude from approximately 3 to 7 standard deviations of the transverse beam distribution. A comparison of halo diffusion and core emittance growth rates is also presented.

  13. Beam halo in high-intensity beams

    International Nuclear Information System (INIS)

    Wangler, T.P.

    1993-01-01

    In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. The beam-halo is of concern for a next generation of cw, high-power proton linacs that could be applied to intense neutron generators for nuclear materials processing. The author describes what has been learned about beam halo and the evolution of space-charge dominated beams using numerical simulations of initial laminar beams in uniform linear focusing channels. Initial results are presented from a study of beam entropy for an intense space-charge dominated beam

  14. Hearing Loss

    Science.gov (United States)

    ... law Sound level, decibels Duration, daily BASED ON OCCUPATIONAL SAFETY & HEALTH ADMINISTRATION, 2008 90 8 hours 92 6 hours 95 4 hours 97 3 hours 100 2 hours 102 1.5 hours 105 1 hour 110 30 minutes 115 15 minutes or less Complications Hearing loss can have a significant effect on your quality ...

  15. Experiencing Loss

    DEFF Research Database (Denmark)

    Kristiansen, Maria; Younis, Tarek; Hassani, Amani

    2015-01-01

    In this article, we explore how Islam, minority status and refugee experiencesintersect in shaping meaning-making processes following bereavement. We do this througha phenomenological analysis of a biographical account of personal loss told by Aisha, a Muslim Palestinian refugee living in Denmark...

  16. Stability diagram of colliding beams

    CERN Document Server

    Buffat, X; Mounet, N; Pieloni, T

    2014-01-01

    The effect of the beam-beam interactions on the stability of impedance mode is discussed. The detuning is evaluated by the means of single particle tracking in arbitrarily complex collision configurations, including lattice non-linearities, and used to numerically evaluate the dispersion integral. This approach also allows the effect of non-Gaussian distributions to be considered. Distributions modified by the action of external noise are discussed.

  17. Summary from working group on multiple beams and funneling

    International Nuclear Information System (INIS)

    Wangler, T.P.

    1985-01-01

    The working group on Multiple Beams and Funneling discussed various topics related to multiple beams and funneling, including (1) design considerations for multiple-beam accelerators; (2) scaling of current, emittance, and brightness for multiple-beam systems; (3) funneling lines using either discrete components or a radiofrequency quadrupole (RFQ) funneling structure; and (4) alternatives to funneling

  18. Properties of the TRIUMF neutron beam

    Energy Technology Data Exchange (ETDEWEB)

    Gan, L. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Physics; Abegg, R. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC (Canada)]|[University of Alberta, Department of Physics, Edmonton, AB (Canada); Berdoz, A.R. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Physics; Birchall, J. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Physics; Campbell, J.R. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Physics; Davis, C.A. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Physics]|[TRIUMF, 4004 Wesbrook Mall, Vancouver, BC (Canada); Green, P.W. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC (Canada)]|[University of Alberta, Department of Physics, Edmonton, AB (Canada); Greeniaus, L.G. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC (Canada)]|[University of Alberta, Department of Physics, Edmonton, AB (Canada); Helmer, R. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC (Canada)]|[University of Alberta, Department of Physics, Edmonton, AB (Canada); Korkmaz, E. [University of Alberta, Department of Physics, Edmonton, AB (Canada); Lee, L. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Physics; Li, J. [University of Alberta, Department of Physics, Edmonton, AB (Canada); Miller, C.A. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC (Canada)]|[University of Alberta, Department of Physics, Edmonton, AB (Canada); Opper, A.K. [University of Alberta, Department of Physics, Edmonton, AB (Canada); Page, S.A. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Physics; Ramsay, W.D. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Physics; Soukup, J. [University of Alberta, Department of Physics, Edmonton, AB (Canada); Van Oers, W.T.H. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Physics; Zhao, J. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Physics

    1995-11-01

    Properties of the TRIUMF neutron beam (4A/2) are presented and compared with a Monte Carlo prediction. The beam intensity profile, energy spectrum and polarization are predicted taking into account the beamline geometry, energy losses in the LD{sub 2} production target, the properties of the vector pd{yields} vector npp reaction, and the scattering of neutrons from the collimator walls. The results allow for improved corrections to systematic errors in a number of TRIUMF neutron experiments. (orig.).

  19. Properties of the TRIUMF neutron beam

    International Nuclear Information System (INIS)

    Gan, L.; Berdoz, A.R.; Green, P.W.; Greeniaus, L.G.; Helmer, R.; Korkmaz, E.; Lee, L.; Miller, C.A.; Opper, A.K.; Page, S.A.; Van Oers, W.T.H.; Zhao, J.

    1995-01-01

    Properties of the TRIUMF neutron beam (4A/2) are presented and compared with a Monte Carlo prediction. The beam intensity profile, energy spectrum and polarization are predicted taking into account the beamline geometry, energy losses in the LD 2 production target, the properties of the vector pd→ vector npp reaction, and the scattering of neutrons from the collimator walls. The results allow for improved corrections to systematic errors in a number of TRIUMF neutron experiments. (orig.)

  20. Investigation of Beam Emittance and Beam Transport Line Optics on Polarization

    Energy Technology Data Exchange (ETDEWEB)

    Fiedler, Andrew [Northern Illinois U.; Syphers, Michael [Fermilab

    2017-10-06

    Effects of beam emittance, energy spread, optical parameters and magnet misalignment on beam polarization through particle transport systems are investigated. Particular emphasis will be placed on the beam lines being used at Fermilab for the development of the muon beam for the Muon g-2 experiment, including comparisons with the natural polarization resulting from pion decay, and comments on the development of systematic correlations among phase space variables.

  1. A simple beam analyser

    International Nuclear Information System (INIS)

    Lemarchand, G.

    1977-01-01

    (ee'p) experiments allow to measure the missing energy distribution as well as the momentum distribution of the extracted proton in the nucleus versus the missing energy. Such experiments are presently conducted on SACLAY's A.L.S. 300 Linac. Electrons and protons are respectively analysed by two spectrometers and detected in their focal planes. Counting rates are usually low and include time coincidences and accidentals. Signal-to-noise ratio is dependent on the physics of the experiment and the resolution of the coincidence, therefore it is mandatory to get a beam current distribution as flat as possible. Using new technologies has allowed to monitor in real time the behavior of the beam pulse and determine when the duty cycle can be considered as being good with respect to a numerical basis

  2. Carbon Fiber Damage in Particle Beam

    CERN Document Server

    Dehning, B; Kroyer, T; Meyer, M; Sapinski, M

    2011-01-01

    Carbon fibers are commonly used as moving targets in beam wire scanners. The heating of the fiber due to energy loss of the particles travelling through is simulated with Geant4. The heating induced by the beam electromagnetic field is estimated with ANSYS. The heat transfer and sublimation processes are modelled. Due to the model nonlinearity, a numerical approach based on discretization of the wire movement is used to solve it for particular beams. Radiation damage to the fiber is estimated with SRIM. The model is tested with available SPS and LEP data and a dedicated damage test on the SPS beam is performed followed by a post-mortem analysis of the wire remnants. Predictions for the LHC beams are made.

  3. First beam splashes at the LHC

    CERN Multimedia

    CERN Bulletin

    2015-01-01

    After a two-year shutdown, the first beams of Run 2 circulated in the LHC last Sunday. On Tuesday, the LHC operators performed dedicated runs to allow some of the experiments to record their first signals coming from particles splashed out when the circulating beams hit the collimators. Powerful reconstruction software then transforms the electronic signals into colourful images.     “Splash” events are used by the experiments to test their numerous subdetectors and to synchronise them with the LHC clock. These events are recorded when the path of particles travelling in the LHC vacuum pipe is intentionally obstructed using collimators – one-metre-long graphite or tungsten jaws that are also used to catch particles that wander too far from the beam centre and to protect the accelerator against unavoidable regular and irregular beam losses. The particles sprayed out of the collision between the beam and the collimators are mostly muons. ATLAS and CMS&...

  4. First absolute measurements of fast-ion losses in the ASDEX Upgrade tokamak

    Science.gov (United States)

    Rodriguez-Ramos, M.; Garcia-Munoz, M.; Jimenez-Ramos, M. C.; Garcia Lopez, J.; Galdon-Quiroga, J.; Sanchis-Sanchez, L.; Ayllon-Guerola, J.; Faitsch, M.; Gonzalez-Martin, J.; Hermann, A.; de Marne, P.; Rivero-Rodriguez, J. F.; Sieglin, B.; Snicker, A.; the ASDEX Upgrade Team

    2017-10-01

    A new diagnostic technique that allows to obtain absolute fluxes of fast-ion losses measured with absolutely calibrated scintillator based fast-ion loss detectors (FILD) is presented here. First absolute fluxes of fast-ion losses have been obtained in the ASDEX Upgrade tokamak. An instrument function that includes the scintillator efficiency, collimator geometry, optical transmission and camera efficiency has been constructed. The scintillator response to deuterium ions in the relevant energy range of fast-ions has been characterized using a tandem accelerator. Absolute flux of neutral beam injection (NBI) prompt losses has been obtained in magnetohydrodynamic quiescent plasmas. The temporal evolution of the heat load measured with FILD follows that measured at the FILD entrance obtained with an Infra-Red camera looking at the FILD detector head. ASCOT simulations are in good agreement with the absolute heat load of NBI prompt losses measured with FILD.

  5. Low-energy beam transport studies supporting the spallation neutron source 1-MW beam operation.

    Science.gov (United States)

    Han, B X; Kalvas, T; Tarvainen, O; Welton, R F; Murray, S N; Pennisi, T R; Santana, M; Stockli, M P

    2012-02-01

    The H(-) injector consisting of a cesium enhanced RF-driven ion source and a 2-lens electrostatic low-energy beam transport (LEBT) system supports the spallation neutron source 1 MW beam operation with ∼38 mA beam current in the linac at 60 Hz with a pulse length of up to ∼1.0 ms. In this work, two important issues associated with the low-energy beam transport are discussed: (1) inconsistent dependence of the post-radio frequency quadrupole accelerator beam current on the ion source tilt angle and (2) high power beam losses on the LEBT electrodes under some off-nominal conditions compromising their reliability.

  6. An interactive beam line simulator module for RHIC

    International Nuclear Information System (INIS)

    MacKay, W.W.

    1997-01-01

    This paper describes the interactive simulation engine, bl, designed for the RHIC project. The program tracks as output to shared memory the central orbit, Twiss and dispersion functions, as well as the 6 x 6 beam hyperellipsoid. Transfer matrices between elements are available via interactive requests. Using a 6-d model, optical elements are modeled with a linear transfer matrix and a vector. The vector allows simulation of misalignments, shifts in field strengths, and beam rigidity. Currently only a linear model is used for elements. In addition to the usual magnets, a foil element is included which can shift the beam's rigidity (resulting from a change of charge and energy loss), as well as increase the momentum spread and emittance. Running as a Glish client, bl can be interfaced to other programs, such as an orbit plotter and a power supply application to give a quick prediction of the beam orbit from actual operating currents in the accelerator. Various strengths and offsets may be changed by sending Glish events to bl

  7. Loss Networks

    OpenAIRE

    Kelly, F. P.

    1991-01-01

    This paper describes work on the stochastic modelling of loss networks. Such systems have long been of interest to telephone engineers and are becoming increasingly important as models of computer and information systems. Throughout the century problems from this field have provided an impetus to the development of probability theory, pure and applied. This paper provides an introduction to the area and a review of recent work.

  8. Design of the torus interface for the neutral beam injectors of Wendelstein 7-X

    Energy Technology Data Exchange (ETDEWEB)

    Nocentini, R., E-mail: riccardo.nocentini@ipp.mpg.de; Heinemann, B.; Riedl, R.; Rust, N.; Orozco, G.

    2015-11-15

    Highlights: • Two NBI injectors are installed in W7-X, each capable of hosting four ion sources. • The NBI boxes and their NBI ports in W7-X are connected by NBI–torus interfaces. • Each NBI–torus interface includes a DN800 bellow, copper scrapers and diagnostics. • The design of the NBI–torus interface has been challenging due to the shape of W7-X. • The design includes the numerical shape optimization of one of the beam scrapers. - Abstract: A neutral beam injection (NBI) heating system for the stellarator project Wendelstein 7-X (W7-X) is currently under construction at the Max Planck Institute for Plasma Physics (IPP) Greifswald, Germany. The NBI at W7-X is based on the similar system in operation on the tokamak ASDEX Upgrade at IPP in Garching, Germany, and makes use of radio-frequency-driven positive ion sources. Two NBI injectors are going to be installed in W7-X, each being capable of hosting four ion sources. Initially each injector is being equipped with two ion sources of 1.8 (2.5) MW beam power each in H (D). Accelerated positive ions are going to be neutralized and transported inside an NBI-box, which also hosts a residual ion dump, titanium sublimation pumps and a calorimeter. The beams are focused at a point 6.5 m downstream of the ion sources and are injected into the plasma vessel of W7-X through two ports. The NBI boxes and their NBI ports are connected by NBI–torus interfaces, which are made of several components that minimize beam losses while protecting the port walls and bellows from energetic re-ionized particles and beam intersection. This paper describes the design of the NBI–torus interface, including the shape optimization of a beam scraper and the integration of beam diagnostics.

  9. Design of four-beam IH-RFQ linear accelerator

    Science.gov (United States)

    Ikeda, Shota; Murata, Aki; Hayashizaki, Noriyosu

    2017-09-01

    The multi-beam acceleration method is an acceleration technique for low-energy high-intensity heavy ion beams, which involves accelerating multiple beams to decrease space charge effects, and then integrating these beams by a beam funneling system. At the Tokyo Institute of Technology a two beam IH-RFQ linear accelerator was developed using a two beam laser ion source with direct plasma injection scheme. This system accelerated a carbon ion beam with a current of 108 mA (54 mA/channel × 2) from 5 up to 60 keV/u. In order to demonstrate that a four-beam IH-RFQ linear accelerator is suitable for high-intensity heavy ion beam acceleration, we have been developing a four-beam prototype. A four-beam IH-RFQ linear accelerator consists of sixteen RFQ electrodes (4 × 4 set) with stem electrodes installed alternately on the upper and lower ridge electrodes. As a part of this development, we have designed a four-beam IH-RFQ linear accelerator using three dimensional electromagnetic simulation software and beam tracking simulation software. From these simulation results, we have designed the stem electrodes, the center plate and the side shells by evaluating the RF properties such as the resonance frequency, the power loss and the electric strength distribution between the RFQ electrodes.

  10. The CMS Beam Conditions and Radiation Monitoring System

    Science.gov (United States)

    Castro, E.; Bacchetta, N.; Bell, A. J.; Dabrowski, A.; Guthoff, M.; Hall-Wilton, R.; Hempel, M.; Henschel, H.; Lange, W.; Lohmann, W.; Müller, S.; Novgorodova, O.; Pfeiffer, D.; Ryjov, V.; Stickland, D.; Schimdt, R.; Walsh, R.

    The Compact Muon Solenoid (CMS) is one of the two large, general purpose experiments situated at the LHC at CERN. As with all high energy physics experiments, knowledge of the beam conditions and luminosity is of vital importance. The Beam Conditions and Radiation Monitoring System (BRM) is installed in CMS to protect the detector and to provide feedback to LHC on beam conditions. It is composed of several sub-systems that measure the radiation level close to or inside all sub-detectors, monitor the beam halo conditions with different time resolution, support beam tuning and protect CMS in case of adverse beam conditions by firing a beam abort signal. This paper presents three of the BRM subsystems: the Fast Beam Conditions Monitor (BCM1F), which is designed for fast flux monitoring, measuring with nanosecond time resolution, both the beam halo and collision products; the Beam Scintillator Counters (BSC), that provide hit rates and time information of beam halo and collision products; and the Beam Conditions Monitors (BCM) used as a protection system that can trigger a beam dump when beam losses occur in order to prevent damage to the pixel and tracker detectors. A description of the systems and a characterization on the basis of data collected during LHC operation is presented.

  11. The gluon beam function at two loops

    Science.gov (United States)

    Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J.

    2014-08-01

    The virtuality-dependent beam function is a universal ingredient in the resummation for observables probing the virtuality of incoming partons, including N -jettiness and beam thrust. We compute the gluon beam function at two-loop order. Together with our previous results for the two-loop quark beam function, this completes the full set of virtuality-dependent beam functions at next-to-next-to-leading order (NNLO). Our results are required to account for all collinear initial-state radiation effects on the N -jettiness event shape through N3LL order. We present numerical results for both the quark and gluon beam functions up to NNLO and N3LL order. Numerically, the NNLO matching corrections are important. They reduce the residual matching scale dependence in the resummed beam function by about a factor of two.

  12. The gluon beam function at two loops

    Energy Technology Data Exchange (ETDEWEB)

    Gaunt, Jonathan R.; Stahlhofen, Maximilian; Tackmann, Frank J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group

    2014-05-15

    The virtuality-dependent beam function is a universal ingredient in the resummation for observables probing the virtuality of incoming partons, including N-jettiness and beam thrust. We compute the gluon beam function at two-loop order. Together with our previous results for the two-loop quark beam function, this completes the full set of virtuality-dependent beam functions at next-to-next-to-leading order (NNLO). Our results are required to account for all collinear ISR effects to the N-jettiness event shape through N{sup 3}LL order. We present numerical results for both the quark and gluon beam functions up to NNLO and N{sup 3}LL order. Numerically, the NNLO matching corrections are important. They reduce the residual matching scale dependence in the resummed beam function by about a factor of two.

  13. Beam instability Workshop - plenary sessions

    International Nuclear Information System (INIS)

    2001-01-01

    The purpose of this workshop was to provide a review of the mechanisms of limiting beam instabilities, their cures, including feedback, and beam measurement for synchrotron radiation light sources. 12 plenary sessions took place whose titles are: 1) challenging brilliance and lifetime issues with increasing currents; 2) limiting instabilities in multibunch; 3) experience from high currents in B factories; 4) longitudinal dynamics in high intensity/bunch; 5) Transverse instabilities for high intensity/bunch; 6) working group introduction from ESRF experience; 7) impedance modelling: simulations, minimization; 8) report on the broadband impedance measurements and modelling workshop; 9) feedback systems for synchrotron light sources; 10) beam instabilities diagnostics; 11) harmonic cavities: the pros and cons; and 12) experimental study of fast beam-ion instabilities at PLS. This document gathers the 12 articles that were presented during these sessions

  14. Literature in Focus Beta Beams: Neutrino Beams

    CERN Multimedia

    2009-01-01

    By Mats Lindroos (CERN) and Mauro Mezzetto (INFN Padova, Italy) Imperial Press, 2009 The beta-beam concept for the generation of electron neutrino beams was first proposed by Piero Zucchelli in 2002. The idea created quite a stir, challenging the idea that intense neutrino beams only could be produced from the decay of pions or muons in classical neutrino beams facilities or in future neutrino factories. The concept initially struggled to make an impact but the hard work by many machine physicists, phenomenologists and theoreticians over the last five years has won the beta-beam a well-earned position as one of the frontrunners for a possible future world laboratory for high intensity neutrino oscillation physics. This is the first complete monograph on the beta-beam concept. The book describes both technical aspects and experimental aspects of the beta-beam, providing students and scientists with an insight into the possibilities o...

  15. A Symplectic Beam-Beam Interaction with Energy Change

    Energy Technology Data Exchange (ETDEWEB)

    Moshammer, Herbert

    2003-07-14

    The performance of many colliding storage rings is limited by the beam-beam interaction. A particle feels a nonlinear force produced by the encountering bunch at the collision. This beam-beam force acts mainly in the transverse directions so that the longitudinal effects have scarcely been studied, except for the cases of a collision with a crossing angle. Recently, however, high luminosity machines are being considered where the beams are focused extensively at the interaction point (IP) so that the beam sizes can vary significantly within the bunch length. Krishnagopal and Siemann have shown that they should not neglect the bunch length effect in this case. The transverse kick depends on the longitudinal position as well as on the transverse position. If they include this effect, however, from the action-reaction principle, they should expect, at the same time, an energy change which depends on the transverse coordinates. Such an effect is reasonably understood from the fact that the beam-beam force is partly due to the electric field, which can change the energy. The action-reaction principle comes from the symplecticity of the reaction: the electromagnetic influence on a particle is described by a Hamiltonian. The symplecticity is one of the most fundamental requirements when studying the beam dynamics. A nonsymplectic approximation can easily lead to unphysical results. In this paper, they propose a simple, approximately but symplectic mapping for the beam-beam interaction which includes the energy change as well as the bunch-length effect. In the next section, they propose the mapping in a Hamiltonian form, which directly assures its symplecticity. Then in section 3, they study the nature of the mapping by interpreting its consequences. The mapping itself is quite general and can be applied to any distribution function. They show in Section 4 how it appears when the distribution function is a Gaussian in transverse directions. The mapping is applied to the

  16. Energy Loss of Coasting Gold Ions and Deuterons in RHIC

    CERN Document Server

    Abreu, N P; Brown, K; Burkhardt, H; Butler, J; Fischer, W; Harvey, M; Tepikian, S

    2008-01-01

    The total energy loss of coasting gold ion beams at two different energies and deuterons at one energy were measured at RHIC, corresponding to a gamma of 75.2, 107.4 and 108.7 respectively. We describe the experiment and observations and compare the measured total energy loss with expectations from ionization losses at the residual gas, the energy loss due to impedance and synchrotron radiation. We find that the measured energy losses are below what is expected from free space synchrotron radiation. We believe that this shows evidence for suppression of synchrotron radiation which is cut off at long wavelength by the presence of the conducting beam pipe.

  17. Particle beams and plasmas

    International Nuclear Information System (INIS)

    Hofmann, A.; Messerschmid, E.; Lawson, J.D.

    1976-01-01

    These lectures present a survey of some of the concepts of plasma physics and look at some situations familiar to particle-accelerator physicists from the point of view of a plasma physicist, with the intention of helping to link together the two fields. At the outset, basic plasma concepts are presented, including definitions of a plasma, characteristic parameters, magnetic pressure and confinement. This is followed by a brief discussion on plasma kinetic theory, non-equilibrium plasma, and the temperature of moving plasmas. Examples deal with beams in the CERN Intersecting Storage Rings as well as with non-steady beams in cyclic accelerators and microwave tubes. In the final chapters, time-varying systems are considered: waves in free space and the effect of cylinder bounds, wave motion in cold stationary plasmas, and waves in plasmas with well-defined streams. The treatment throughout is informal, with emphasis on the essential physical properties of continuous beams in accelerators and storage rings in relation to the corresponding problems in plasma physics and microwave tubes. (Author)

  18. ISR beam scrapers

    CERN Multimedia

    CERN PhotoLab

    1972-01-01

    Beam scrapers seen in the direction of the beam. The two horizontal scraper foils are near the centre of the beam pipe andthe two scrapers for protection of the vacuum chamber are further outside. In the lower part of the beam pipe is the vertical halo scraping blade.

  19. Telecommunication using muon beams

    International Nuclear Information System (INIS)

    Arnold, R.C.

    1976-01-01

    Telecommunication is effected by generating a beam of mu mesons or muons, varying a property of the beam at a modulating rate to generate a modulated beam of muons, and detecting the information in the modulated beam at a remote location

  20. Analysis of orthotropic beams

    Science.gov (United States)

    Jen Y. Liu; S. Cheng

    1979-01-01

    A plane-stress analysis of orthotropic or isotropic beams is presented. The loading conditions considered are: (1) a concentrated normal load arbitrarily located on the beam, and (2) a distributed normal load covering an arbitrary length of the beam. exhibit close agreement with existing experimental data from Sitka spruce beams. Other loading conditions can similarly...

  1. Telecommunication using muon beams

    Science.gov (United States)

    Arnold, Richard C.

    1976-01-01

    Telecommunication is effected by generating a beam of mu mesons or muons, varying a property of the beam at a modulating rate to generate a modulated beam of muons, and detecting the information in the modulated beam at a remote location.

  2. Whole-grain ready-to-eat oat cereal, as part of a dietary program for weight loss, reduces low-density lipoprotein cholesterol in adults with overweight and obesity more than a dietary program including low-fiber control foods.

    Science.gov (United States)

    Maki, Kevin C; Beiseigel, Jeannemarie M; Jonnalagadda, Satya S; Gugger, Carolyn K; Reeves, Matthew S; Farmer, Mildred V; Kaden, Valerie N; Rains, Tia M

    2010-02-01

    Weight loss and consumption of viscous fibers both lower low-density lipoprotein (LDL) cholesterol levels. We evaluated whether or not a whole-grain, ready-to-eat (RTE) oat cereal containing viscous fiber, as part of a dietary program for weight loss, lowers LDL cholesterol levels and improves other cardiovascular disease risk markers more than a dietary program alone. Randomized, parallel-arm, controlled trial. Free-living, overweight and obese adults (N=204, body mass index 25 to 45) with baseline LDL cholesterol levels 130 to 200 mg/dL (3.4 to 5.2 mmol/L) were randomized; 144 were included in the main analysis of participants who completed the trial without significant protocol violations. Two portions per day of whole-grain RTE oat cereal (3 g/day oat b-glucan) or energy-matched low-fiber foods (control), as part of a reduced energy ( approximately 500 kcal/day deficit) dietary program that encouraged limiting consumption of foods high in energy and fat, portion control, and regular physical activity. Fasting lipoprotein levels, waist circumference, triceps skinfold thickness, and body weight were measured at baseline and weeks 4, 8, 10, and 12. LDL cholesterol level was reduced significantly more with whole-grain RTE oat cereal vs control (-8.7+/-1.0 vs -4.3+/-1.1%, P=0.005). Total cholesterol (-5.4+/-0.8 vs -2.9+/-0.9%, P=0.038) and non-high-density lipoprotein-cholesterol (-6.3+/-1.0 vs -3.3+/-1.1%, P=0.046) were also lowered significantly more with whole-grain RTE oat cereal, whereas high-density lipoprotein and triglyceride responses did not differ between groups. Weight loss was not different between groups (-2.2+/-0.3 vs -1.7+/-0.3 kg, P=0.325), but waist circumference decreased more (-3.3+/-0.4 vs -1.9+/-0.4 cm, P=0.012) with whole-grain RTE oat cereal. Larger reductions in LDL, total, and non-high-density lipoprotein cholesterol levels and waist circumference were evident as early as week 4 in the whole-grain RTE oat cereal group. Consumption of a

  3. Diagnostics for the ATA beam propagation experiments

    International Nuclear Information System (INIS)

    Fessenden, T.J.; Atchison, W.L.; Barletta, W.A.

    1981-11-01

    This report contains a discussion of the diagnostics required for the beam propagation experiment to be done with the ATA accelerator. Included are a list of the diagnostics needed; a description of the ATA experimental environment; the status of beam diagnostics available at Livermore including recent developments, and a prioritized list of accelerator and propagation diagnostics under consideration or in various stages of development

  4. Diagnostics for the ATA beam propagation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Fessenden, T.J.; Atchison, W.L.; Barletta, W.A.

    1981-11-01

    This report contains a discussion of the diagnostics required for the beam propagation experiment to be done with the ATA accelerator. Included are a list of the diagnostics needed; a description of the ATA experimental environment; the status of beam diagnostics available at Livermore including recent developments, and a prioritized list of accelerator and propagation diagnostics under consideration or in various stages of development.

  5. Beam dynamics design of the Compact Linear Collider Drive Beam injector

    International Nuclear Information System (INIS)

    Hajari, Sh. Sanaye; Shaker, H.; Doebert, S.

    2015-01-01

    In the Compact Linear Collider (CLIC) the RF power for the acceleration of the Main Beam is extracted from a high-current Drive Beam that runs parallel to the main linac. The longitudinal and transverse beam dynamics of the Drive Beam injector has been studied in detail and optimized. The injector consists of a thermionic gun followed by a bunching system, some accelerating structures, and a magnetic chicane. The bunching system contains three sub-harmonic bunchers, a prebuncher, and a traveling wave buncher all embedded in a solenoidal magnetic field. The main characteristic of the Drive Beam injector is the phase coding process done by the sub-harmonic bunching system operating at half the acceleration frequency. This process is essential for the frequency multiplication of the Drive Beam. During the phase coding process the unwanted satellite bunches are produced that adversely affects the machine power efficiency. The main challenge is to reduce the population of particles in the satellite bunches in the presence of strong space-charge forces due to the high beam current. The simulation of the beam dynamics has been carried out with PARMELA with the goal of optimizing the injector performance compared to the existing model studied for the Conceptual Design Report (CDR). The emphasis of the optimization was on decreasing the satellite population, the beam loss in the magnetic chicane and limiting the beam emittance growth in transverse plane

  6. Pump apparatus including deconsolidator

    Energy Technology Data Exchange (ETDEWEB)

    Sonwane, Chandrashekhar; Saunders, Timothy; Fitzsimmons, Mark Andrew

    2014-10-07

    A pump apparatus includes a particulate pump that defines a passage that extends from an inlet to an outlet. A duct is in flow communication with the outlet. The duct includes a deconsolidator configured to fragment particle agglomerates received from the passage.

  7. LANSCE beam current limiter

    International Nuclear Information System (INIS)

    Gallegos, F.R.

    1996-01-01

    The Radiation Security System (RSS) at the Los Alamos Neutron Science Center (LANSCE) provides personnel protection from prompt radiation due to accelerated beam. Active instrumentation, such as the Beam Current Limiter, is a component of the RSS. The current limiter is designed to limit the average current in a beam line below a specific level, thus minimizing the maximum current available for a beam spill accident. The beam current limiter is a self-contained, electrically isolated toroidal beam transformer which continuously monitors beam current. It is designed as fail-safe instrumentation. The design philosophy, hardware design, operation, and limitations of the device are described

  8. Beam characteristics and radiation output of a kilovoltage cone-beam CT

    Science.gov (United States)

    Ding, George X.; Coffey, Charles W.

    2010-09-01

    This study presents beam characteristics of five recently available x-ray beams produced by an on-board imager (OBI 1.4) for acquiring kilovoltage cone-beam computed tomography (kV-CBCT) and investigates suitable methods for the beam radiation output determination resulting from an image acquisition. Both are essential for commissioning an x-ray beam in a radiotherapy treatment planning system. The BEAM/DOSXYZnrc Monte Carlo codes were used in the investigation. The simulated beam data were benchmarked against measurements. Three different commercially available plastic phantom materials are investigated as liquid water substitutes in the beam radiation output determination. Ionization chambers are used for the measurements. Five kV-CBCT beam characteristics including photon fluence, average beam energy and photon spectra are generated from Monte Carlo simulations. The Monte Carlo calculated dose profiles are validated by measurements. The fluence of kV-CBCT beams is strongly dependent on the geometry of added filters as well as X and Y beam collimations. The potential errors of determining the beam output of a kV-CBCT beam in Solid Water and PMMA phantoms may approach 8% and 20%, respectively, for use in a conventional treatment planning system, whereas using the Plastic Water low-energy range (PW-LR) phantom results in errors within 2%. The Monte Carlo simulation is essential in providing the parameters of an x-ray beam which are needed for the commissioning of a kV-CBCT beam in a radiotherapy treatment planning system. The PW-LR phantom is a suitable liquid water substitute in the beam output determination resulting from a kV-CBCT acquisition.

  9. Sudden Sensorineural Hearing Loss

    Science.gov (United States)

    Kuhn, Maggie; Heman-Ackah, Selena E.; Shaikh, Jamil A.

    2011-01-01

    Sudden sensorineural hearing loss (SSNHL) is commonly encountered in audiologic and otolaryngologic practice. SSNHL is most commonly defined as sensorineural hearing loss of 30dB or greater over at least three contiguous audiometric frequencies occurring within a 72-hr period. Although the differential for SSNHL is vast, for the majority of patients an etiologic factor is not identified. Treatment for SSNHL of known etiology is directed toward that agent, with poor hearing outcomes characteristic for discoverable etiologies that cause inner ear hair cell loss. Steroid therapy is the current mainstay of treatment of idiopathic SSNHL in the United States. The prognosis for hearing recovery for idiopathic SSNHL is dependent on a number of factors including the severity of hearing loss, age, presence of vertigo, and shape of the audiogram. PMID:21606048

  10. Unified monitors for extracted proton beam diagnostics in the IHEP channels

    International Nuclear Information System (INIS)

    Gvakhariya, T.V.; Gres', V.N.; Davydenko, Yu.P.

    1985-01-01

    Equipment complex, used for extracted beam monitoring at the U-70 synchrotron is described. The main parameters of detectors, used for the beam profile and position, its intensity and loss measurement, as well as of data acquisition and processing system are considered. For the beam profile and position measuring secondary emission multichannel chambers are used. To determine the beam intensity during fast extraction a beam current transformer is used, and as for the slow extractionasecondary emission sealed chamber is used. Beam losses are measured with the use of ionization chambers with geometry close to2π

  11. Energy Losses Estimation During Pulsed-Laser Seam Welding

    Science.gov (United States)

    Sebestova, Hana; Havelkova, Martina; Chmelickova, Hana

    2014-06-01

    The finite-element tool SYSWELD (ESI Group, Paris, France) was adapted to simulate pulsed-laser seam welding. Besides temperature field distribution, one of the possible outputs of the welding simulation is the amount of absorbed power necessary to melt the required material volume including energy losses. Comparing absorbed or melting energy with applied laser energy, welding efficiencies can be calculated. This article presents achieved results of welding efficiency estimation based on the assimilation both experimental and simulation output data of the pulsed Nd:YAG laser bead on plate welding of 0.6-mm-thick AISI 304 stainless steel sheets using different beam powers.

  12. Strengthening and repair of RC beams with sugarcane bagasse fiber reinforced cement mortar

    Science.gov (United States)

    Syamir Senin, Mohamad; Shahidan, Shahiron; Maarof, M. Z. Md; Syazani Leman, Alif; Zuki, S. S. Mohd; Azmi, M. A. Mohammad

    2017-11-01

    The use of a jacket made of fiber reinforced cement mortar with tensile hardening behaviour for strengthening RC beams was investigated in this study. A full-scale test was conducted on beams measuring 1000mm in length. A 25mm jacket was directly applied to the surface of the beams to test its ability to repair and strengthen the beams. The beams were initially damaged and eventually repaired. Three types of beams which included unrepaired beams, beams repaired with normal mortar jacket and beams repaired with 10% sugarcane bagasse fiber mortar jacket were studied. The jacket containing 10% of sugarcane bagasse fiber enhanced the flexural strength of the beams.

  13. Electron beam diagnostic system using computed tomography and an annular sensor

    Science.gov (United States)

    Elmer, John W.; Teruya, Alan T.

    2014-07-29

    A system for analyzing an electron beam including a circular electron beam diagnostic sensor adapted to receive the electron beam, the circular electron beam diagnostic sensor having a central axis; an annular sensor structure operatively connected to the circular electron beam diagnostic sensor, wherein the sensor structure receives the electron beam; a system for sweeping the electron beam radially outward from the central axis of the circular electron beam diagnostic sensor to the annular sensor structure wherein the electron beam is intercepted by the annular sensor structure; and a device for measuring the electron beam that is intercepted by the annular sensor structure.

  14. Electron-impact excitation of multiply-charged ions using energy loss in merged beams: e + Si3+(3s2S1/2) → e + Si3+(3p2P1/2,3/2)

    International Nuclear Information System (INIS)

    Wahlin, E.K.; Thompson, J.S.; Dunn, G.H.; Phaneuf, R.A.; Gregory, D.C.; Smith, A.C.H.

    1990-01-01

    For the first time absolute total cross sections for electron-impact excitation of a multiply-charged ion have been measured using an electron-energy-loss technique. Measurements were made near threshold for the process e + Si 3+ (3s 2 S 1/2 ) → e + Si 3+ (3p 2 P 1/2 , 3/2 ) -- 8.88 eV. The 10 -15 cm 2 measured cross section agrees with results of 7-state close coupling calculations to better than the ±20% (90% CL) total uncertainty of the measurements. Convoluting the theoretical curve with a Gaussian energy distribution indicates an energy width of 0.15 approx-lt ΔE approx-lt 0.20 eV. 12 refs., 2 figs

  15. The beam dump tunnels

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    In these images workers are digging the tunnels that will be used to dump the counter-circulating beams. Travelling just a fraction under the speed of light, the beams at the LHC will each carry the energy of an aircraft carrier travelling at 12 knots. In order to dispose of these beams safely, a beam dump is used to extract the beam and diffuse it before it collides with a radiation shielded graphite target.

  16. Ion beam diagnosis

    International Nuclear Information System (INIS)

    Strehl, P.

    1994-04-01

    This report is an introduction to ion beam diagnosis. After a short description of the most important ion beam parameters measurements of the beam current by means of Faraday cups, calorimetry, and beam current transformers and measurements of the beam profile by means of viewing screens, profile grids and scanning devices, and residual gas ionization monitors are described. Finally measurements in the transverse and longitudinal phase space are considered. (HSI)

  17. Optical modulator including grapene

    Science.gov (United States)

    Liu, Ming; Yin, Xiaobo; Zhang, Xiang

    2016-06-07

    The present invention provides for a one or more layer graphene optical modulator. In a first exemplary embodiment the optical modulator includes an optical waveguide, a nanoscale oxide spacer adjacent to a working region of the waveguide, and a monolayer graphene sheet adjacent to the spacer. In a second exemplary embodiment, the optical modulator includes at least one pair of active media, where the pair includes an oxide spacer, a first monolayer graphene sheet adjacent to a first side of the spacer, and a second monolayer graphene sheet adjacent to a second side of the spacer, and at least one optical waveguide adjacent to the pair.

  18. EFFECT OF SPACE CHARGE ON STABILITY OF BEAM DISTRIBUTION IN THE SNS RING

    International Nuclear Information System (INIS)

    FEDOTOV, A.V.; WEI, J.; GLUCKSTERN, R.L.

    2001-01-01

    In the Spallation Neutron Source (SNS) ring, multi-turn injection is employed to obtain a large transverse beam size which significantly reduces the space-charge tune shift of the accumulated beam. Careful choice of the painting scheme and bump function is required to obtain the desired beam profile together with low beam loss. In this paper we examine, both analytically and numerically, the effect of the space charge on the beam profile during multi-turn injection painting

  19. Statics and rotational dynamics of composite beams

    CERN Document Server

    Ghorashi, Mehrdaad

    2016-01-01

    This book presents a comprehensive study of the nonlinear statics and dynamics of composite beams and consists of solutions with and without active elements embedded in the beams. The static solution provides the initial conditions for the dynamic analysis. The dynamic problems considered include the analyses of clamped (hingeless) and articulated (hinged) accelerating rotating beams. Two independent numerical solutions for the steady state and the transient responses are presented. The author illustrates that the transient solution of the nonlinear formulation of accelerating rotating beam converges to the steady state solution obtained by the shooting method. Other key areas considered include calculation of the effect of perturbing the steady state solution, coupled nonlinear flap-lag dynamics of a rotating articulated beam with hinge offset and aerodynamic damping, and static and dynamic responses of nonlinear composite beams with embedded anisotropic piezo-composite actuators. The book is intended as a t...

  20. Energy consumption of SO2 removal from humid air under electron beam and electric field influence

    International Nuclear Information System (INIS)

    Nichipor, H.; Radjuk, E.; Chmielewski, A.G.; Zimek, Z.

    1998-01-01

    The kinetic of SO 2 oxidation in humid air under influence of electron beam and electrical field was investigated by computer simulation method in steady state and pulse mode. SO 2 oxidation process was stimulated by radical and ion reactions. The calculation model has included 46 different particles and 160 chemical reactions. Gas mixture containing 1000 ppm of SO 2 concentration was investigated at temperature T=67 deg. C and pressure p=1 at. Water content was within the range 2-12%. Electron beam parameters were as follows: average beam current density 0.0032-3,2 mA/cm 2 , pulse duration 400 μs, repetition rate 50 Hz. Electrical field density was E/n =10 -15 Vcm 2 . Electrical pulse duration was changed within the range 5 x10 -7 -10 -5 s. The influence of the parameters of synchronized electron beam and electrical field pulses on energy deposition was under consideration. Energy cost of SO 2 removal on 90% level was estimated in steady state and pulse modes. It was found that total electron beam and electrical field energy losses in pulse mode are 6 times lower to compare with steady state conditions. The optimum of electrical field pulse duration from point of view minimum energy cost of SO 2 removal was found for different electron beam pulse current levels

  1. ALCBEAM - Neutral beam formation and propagation code for beam-based plasma diagnostics

    Science.gov (United States)

    Bespamyatnov, I. O.; Rowan, W. L.; Liao, K. T.

    2012-03-01

    ALCBEAM is a new three-dimensional neutral beam formation and propagation code. It was developed to support the beam-based diagnostics installed on the Alcator C-Mod tokamak. The purpose of the code is to provide reliable estimates of the local beam equilibrium parameters: such as beam energy fractions, density profiles and excitation populations. The code effectively unifies the ion beam formation, extraction and neutralization processes with beam attenuation and excitation in plasma and neutral gas and beam stopping by the beam apertures. This paper describes the physical processes interpreted and utilized by the code, along with exploited computational methods. The description is concluded by an example simulation of beam penetration into plasma of Alcator C-Mod. The code is successfully being used in Alcator C-Mod tokamak and expected to be valuable in the support of beam-based diagnostics in most other tokamak environments. Program summaryProgram title: ALCBEAM Catalogue identifier: AEKU_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKU_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 66 459 No. of bytes in distributed program, including test data, etc.: 7 841 051 Distribution format: tar.gz Programming language: IDL Computer: Workstation, PC Operating system: Linux RAM: 1 GB Classification: 19.2 Nature of problem: Neutral beams are commonly used to heat and/or diagnose high-temperature magnetically-confined laboratory plasmas. An accurate neutral beam characterization is required for beam-based measurements of plasma properties. Beam parameters such as density distribution, energy composition, and atomic excited populations of the beam atoms need to be known. Solution method: A neutral beam is initially formed as an ion beam which is extracted from

  2. New ORNL neutral beam transport system

    International Nuclear Information System (INIS)

    Stirling, W.L.; Davis, R.C.; Haselton, H.H.; Schnechter, D.E.; Tsai, C.C.

    1977-01-01

    The Princeton Large Torus (PLT) neutral beam injection systems have proven themselves to be a solid foundation on which next generation systems can be based. There are two areas in the new systems receiving particular emphasis: (a) increased power per beam line and (b) higher beam transmission efficiency. Two different methods are being investigated to improve the transmission efficiency. First the drift tube region, the region of the beam line between the vacuum chamber housing the ion source and the torus, is being enlarged. In this manner a second, large cryopump will be installed in the drift tube to lower the pressure to approx.10 -5 torr. Thus, neutral beam reionization on the background gas will be significantly reduced from the measured losses at a few 10 -4 torr of the PLT system. Second, the beam divergence will be reduced by application of one or more of three known techniques developed on a single aperture source in the laboratory. Each of these methods has shown a reduction in single beamlet divergence from theta/sub HWHM/ approx. 1 0 to approx.0.5 0 . The low beamlet divergence coupled with a differentially pumped drift tube will effectively accommodate the larger ion sources under development. All future beam line systems will benefit either directly or indirectly from the experience gained operating and upgrading the PLT beam line concept

  3. CTF3 Drive Beam Injector Optimisation

    CERN Document Server

    AUTHOR|(CDS)2082899; Doebert, S

    2015-01-01

    In the Compact Linear Collider (CLIC) the RF power for the acceleration of the Main Beam is extracted from a high-current Drive Beam that runs parallel to the main linac. The main feasibility issues of the two-beam acceleration scheme are being demonstrated at CLIC Test Facility 3 (CTF3). The CTF3 Drive Beam injector consists of a thermionic gun followed by the bunching system and two accelerating structures all embedded in solenoidal magnetic field and a magnetic chicane. Three sub-harmonic bunchers (SHB), a prebuncher and a travelling wave buncher constitute the bunching system. The phase coding process done by the sub-harmonic bunching system produces unwanted satellite bunches between the successive main bunches. The beam dynamics of the CTF3 Drive Beam injector is reoptimised with the goal of improving the injector performance and in particular decreasing the satellite population, the beam loss in the magnetic chicane and the beam emittance in transverse plane compare to the original model based on P. Ur...

  4. Low-Loss Waveguides for Terahertz Frequencies

    Science.gov (United States)

    Siegel, Peter; Yeh, Cavour; Shimabukuro, Fred; Fraser, Scott

    2008-01-01

    Hollow-core, periodic bandgap (HCPBG) flexible waveguides have been proposed as a means of low-loss transmission of electromagnetic signals in the frequency range from about 300 GHz to 30 THz. This frequency range has been called the "terahertz gap" because it has been little utilized: Heretofore, there has been no way of low-loss guiding of terahertz beams other than by use of fixed-path optical beam guides with lenses and mirrors or multimode waveguides that cannot maintain mode purity around bends or modest discontinuities.

  5. A combined molecular dynamics and Monte Carlo simulation of the spatial distribution of energy deposition by proton beams in liquid water

    International Nuclear Information System (INIS)

    Garcia-Molina, Rafael; Abril, Isabel; Heredia-Avalos, Santiago; Kyriakou, Ioanna; Emfietzoglou, Dimitris

    2011-01-01

    We have evaluated the spatial distribution of energy deposition by proton beams in liquid water using the simulation code SEICS (Simulation of Energetic Ions and Clusters through Solids), which combines molecular dynamics and Monte Carlo techniques and includes the main interaction phenomena between the projectile and the target constituents: (i) the electronic stopping force due to energy loss to target electronic excitations, including fluctuations due to the energy-loss straggling, (ii) the elastic scattering with the target nuclei, with their corresponding energy loss and (iii) the dynamical changes in projectile charge state due to electronic capture and loss processes. An important feature of SEICS is the accurate account of the excitation spectrum of liquid water, based on a consistent solid-state description of its energy-loss-function over the whole energy and momentum space. We analyse how the above-mentioned interactions affect the depth distribution of the energy delivered in liquid water by proton beams with incident energies of the order of several MeV. Our simulations show that the position of the Bragg peak is determined mainly by the stopping power, whereas its width can be attributed to the energy-loss straggling. Multiple elastic scattering processes contribute slightly only at the distal part of the Bragg peak. The charge state of the projectiles only changes when approaching the end of their trajectories, i.e. near the Bragg peak. We have also simulated the proton-beam energy distribution at several depths in the liquid water target, and found that it is determined mainly by the fluctuation in the energy loss of the projectile, evaluated through the energy-loss straggling. We conclude that a proper description of the target excitation spectrum as well as the inclusion of the energy-loss straggling is essential in the calculation of the proton beam depth-dose distribution.

  6. Modeling transmission and scatter for photon beam attenuators.

    Science.gov (United States)

    Ahnesjö, A; Weber, L; Nilsson, P

    1995-11-01

    The development of treatment planning methods in radiation therapy requires dose calculation methods that are both accurate and general enough to provide a dose per unit monitor setting for a broad variety of fields and beam modifiers. The purpose of this work was to develop models for calculation of scatter and transmission for photon beam attenuators such as compensating filters, wedges, and block trays. The attenuation of the beam is calculated using a spectrum of the beam, and a correction factor based on attenuation measurements. Small angle coherent scatter and electron binding effects on scattering cross sections are considered by use of a correction factor. Quality changes in beam penetrability and energy fluence to dose conversion are modeled by use of the calculated primary beam spectrum after passage through the attenuator. The beam spectra are derived by the depth dose effective method, i.e., by minimizing the difference between measured and calculated depth dose distributions, where the calculated distributions are derived by superposing data from a database for monoenergetic photons. The attenuator scatter is integrated over the area viewed from the calculation point of view using first scatter theory. Calculations are simplified by replacing the energy and angular-dependent cross-section formulas with the forward scatter constant r2(0) and a set of parametrized correction functions. The set of corrections include functions for the Compton energy loss, scatter attenuation, and secondary bremsstrahlung production. The effect of charged particle contamination is bypassed by avoiding use of dmax for absolute dose calibrations. The results of the model are compared with scatter measurements in air for copper and lead filters and with dose to a water phantom for lead filters for 4 and 18 MV. For attenuated beams, downstream of the buildup region, the calculated results agree with measurements on the 1.5% level. The accuracy was slightly less in situations

  7. Three-beam double stimulated Raman scatterings: Cascading configuration

    Science.gov (United States)

    Rao, B. Jayachander; Cho, Minhaeng

    2018-03-01

    Two-beam stimulated Raman scattering (SRS) has been used in diverse label-free spectroscopy and imaging applications of live cells, biological tissues, and functional materials. Recently, we developed a theoretical framework for the three-beam double SRS processes that involve pump, Stokes, and depletion beams, where the pump-Stokes and pump-depletion SRS processes compete with each other. It was shown that the net Stokes gain signal can be suppressed by increasing the depletion beam intensity. The theoretical prediction has been experimentally confirmed recently. In the previous scheme for a selective suppression of one SRS by making it compete with another SRS, the two SRS processes occur in a parallel manner. However, there is another possibility of three-beam double SRS scheme that can be of use to suppress either Raman gain of the Stokes beam or Raman loss of the pump beam by depleting the Stokes photons with yet another SRS process induced by the pair of Stokes and another (second) Stokes beam. This three-beam double SRS process resembles a cascading energy transfer process from the pump beam to the first Stokes beam (SRS-1) and subsequently from the first Stokes beam to the second Stokes beam (SRS-2). Here, the two stimulated Raman gain-loss processes are associated with two different Raman-active vibrational modes of solute molecule. In the present theory, both the radiation and the molecules are treated quantum mechanically. We then show that the cascading-type three-beam double SRS can be described by coupled differential equations for the photon numbers of the pump and Stokes beams. From the approximate solutions as well as exact numerical calculation results for the coupled differential equations, a possibility of efficiently suppressing the stimulated Raman loss of the pump beam by increasing the second Stokes beam intensity is shown and discussed. To further prove a potential use of this scheme for developing a super-resolution SRS microscopy, we

  8. Revisit of combined parallel-beam/cone-beam or fan-beam/cone-beam imaging.

    Science.gov (United States)

    Zeng, Gengsheng L

    2013-10-01

    This aim of this paper is to revisit the parallel-beam/cone-beam or fan-beam/cone-beam imaging configuration, and to investigate whether this configuration has any advantages. Twenty years ago, it was suggested to simultaneously use a parallel-beam (or a fan-beam) collimator and a cone-beam collimator to acquire single photon emission computed tomography data. The motivation was that the parallel-beam (or the fan-beam) collimator can provide sufficient sampling, while the cone-beam collimator is able to provide higher photon counts. Even with higher total counts, this hybrid system does not give significant improvement (if any) in terms of image noise and artifacts reduction. If a conventional iterative maximum-likelihood expectation-maximization algorithm is used to reconstruct the image, the resultant reconstruction may be worse than the parallel-beam-only (or fan-beam-only) system. This paper uses the singular value decomposition (SVD) analysis to explain this phenomenon. The SVD results indicate that the parallel-beam-only and the fan-beam-only system outperform the combined systems. The optimal imaging system does not necessary to be the one that generates the projections with highest signal-to-noise ratio and best resolution.

  9. A Southern African positron beam

    International Nuclear Information System (INIS)

    Britton, D.T.; Haerting, M.; Teemane, M.R.B.; Mills, S.; Nortier, F.M.; Van der Walt, T.N.

    1997-01-01

    The first stage of a state of the art positron beam, being constructed at the University of Cape Town, is currently being brought into operation. This is the first positron beam on the African continent, as well as being the first positron beam dedicated to solid and surface studies in the southern hemisphere. The project also contains a high proportion of local development, including the encapsulated 22 Na positron source developed by our collaboration. Novel features in the design include a purely magnetic in-line deflector, working in the solenoidal guiding field, to eliminate unmoderated positrons and block the direct line of sight to the source. A combined magnetic projector and single pole probe forming lens is being implemented in the second phase of construction to achieve a spot size of 10 μm without remoderation

  10. Weight-loss medicines

    Science.gov (United States)

    Prescription weight loss drugs; Diabetes - weight loss drugs; Obesity - weight loss drugs; Overweight - weight loss drugs ... Several weight-loss medicines are available. About 5 to 10 pounds (2 to 4.5 kilograms) can be lost by ...

  11. Extraction and beam transfer for the SHiP facility

    CERN Document Server

    Goddard, Brennan; Borburgh, Jan; Balhan, Bruno; Le Godec, Gilles; Zerlauth, Markus; Tommasini, Davide; Kain, Verena; Cornelis, Karel; Wenninger, Jorg; Jensen, Lars; Todd, Benjamin; Bauche, Jeremie; Puccio, Bruno

    2015-01-01

    This document summarises the key feasibility issues associated with the SPS extraction and beam transfer systems required for the SHiP facility. It describes the expected performance limits of the electrostatic septa, the expected beam losses during extraction and consequences, the design of the new beamline geometry and equipment systems and the expected extracted spill structure.

  12. Biologicals and bone loss

    NARCIS (Netherlands)

    Krieckaert, C.L.M.; Lems, W.F.

    2012-01-01

    Inflammatory joint diseases are associated with extra-articular side effects including bone involvement.There is an increased risk of osteoporotic fractures. The pathogeneses of local and generalized bone loss share a common pathway. Early and active rheumatoid arthritis is associated with

  13. Deafness and Hearing Loss.

    Science.gov (United States)

    National Information Center for Children and Youth with Disabilities, Washington, DC.

    This brief overview provides information on the definition, incidence, and characteristics of children with hearing impairments and deafness. The federal definitions of hearing impairment and deafness are provided. The different types of hearing loss are noted, including: (1) conductive (caused by diseases or obstructions in the outer or middle…

  14. Research and development of advanced materials using ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Namba, Susumu [Nagasaki Inst. of Applied Science, Nagasaki (Japan)

    1997-03-01

    A wide range of research and development activities of advanced material synthesis using ion beams will be discussed, including ion beam applications to the state-of-the-art electronics from giant to nano electronics. (author)

  15. Studies on heavy ion losses from collimation cleaning at the LHC

    CERN Document Server

    Hermes, P D; Jowett, J M; Redaelli, S; Salvachua, B M; Valentino, G; Wollmann, D

    2015-01-01

    The LHC collimation system protects superconducting magnets from beam losses. By design, it was optimized for the high-intensity proton challenges but so far provided adequate protection also during the LHC heavy-ion runs with 208Pb82+ ions up to a beam energy of 4 Z TeV. Ion beam cleaning brings specific challenges due to different physical interactions with the collimator materials and might require further improvements for operation at 7 Z TeV. In this article, we study heavy-ion beam losses leaking out of the LHC collimation system, both in measurement and simulations. The simulations are carried out using both ICOSIM, with a simplified ion physics model implemented, and SixTrack, including more detailed starting conditions from FLUKA but without including online scattering in subsequent collimator hits. The results agree well with measurements overall, although some discrepancies are present. The reasons for the discrepancies are investigated and, on this basis, the requirements for an improved simulatio...

  16. Integrated control system for electron beam processes

    Science.gov (United States)

    Koleva, L.; Koleva, E.; Batchkova, I.; Mladenov, G.

    2018-03-01

    The ISO/IEC 62264 standard is widely used for integration of the business systems of a manufacturer with the corresponding manufacturing control systems based on hierarchical equipment models, functional data and manufacturing operations activity models. In order to achieve the integration of control systems, formal object communication models must be developed, together with manufacturing operations activity models, which coordinate the integration between different levels of control. In this article, the development of integrated control system for electron beam welding process is presented as part of a fully integrated control system of an electron beam plant, including also other additional processes: surface modification, electron beam evaporation, selective melting and electron beam diagnostics.

  17. THE RHIC BEAM ABORT KICKER SYSTEM

    International Nuclear Information System (INIS)

    Hahn, H.

    1999-01-01

    THE ENERGY STORED IN THE RHIC BEAM IS ABOUT 200 KJ PER RING AT DESIGN ENERGY AND INTENSITY. TO PREVENT QUENCHING OF THE SUPERCONDUCTING MAGNETS OR MATERIAL DAMAGE, THE BEAM WILL BE SAFELY DISPOSED OF BY AN INTERNAL BEAM ABORT SYSTEM, WHICH INCLUDES THE KICKER MAGNETS, THE PULSED POWER SUPPLIES, AND THE DUMP ABSORBER. DISPOSAL OF HEAVY IONS, SUCH AS GOLD, IMPOSES DESIGN CONSTRAINTS MORE SEVERE THAN THOSE FOR PROTON BEAMS OF EQUAL INTENSITY. IN ORDER TO MINIMIZE THE THERMAL SHOCK IN THE CARBON-FIBER DUMP BLOCK, THE BUNCHES MUST BE LATERALLY DISPERSED

  18. Beam structures classical and advanced theories

    CERN Document Server

    Carrera, Erasmo; Petrolo, Marco

    2011-01-01

    Beam theories are exploited worldwide to analyze civil, mechanical, automotive, and aerospace structures. Many beam approaches have been proposed during the last centuries by eminent scientists such as Euler, Bernoulli, Navier, Timoshenko, Vlasov, etc.  Most of these models are problem dependent: they provide reliable results for a given problem, for instance a given section and cannot be applied to a different one. Beam Structures: Classical and Advanced Theories proposes a new original unified approach to beam theory that includes practically all classical and advanced models for be

  19. LHC Abort Gap Filling by Proton Beam

    CERN Document Server

    Fartoukh, Stéphane David; Shaposhnikova, Elena

    2004-01-01

    Safe operation of the LHC beam dump relies on the possibility of firing the abort kicker at any moment during beam operation. One of the necessary conditions for this is that the number of particles in the abort gap should be below some critical level defined by quench limits. Various scenarios can lead to particles filling the abort gap. Time scales associated with these scenarios are estimated for injection energy and also coast where synchrotron radiation losses are not negligible for uncaptured particle motion. Two cases are considered, with RF on and RF off. The equilibrium distribution of lost particles in the abort gap defines the requirements for maximum tolerable relative loss rate and as a consequence the minimum acceptable longitudinal lifetime of the proton beam in collision.

  20. Insulating materials resistance in intense radiation beams

    International Nuclear Information System (INIS)

    Oproiu, Constantin; Martin, Diana; Scarlat, Florin; Timus, Dan; Brasoveanu, Mirela; Nemtanu, Monica

    2002-01-01

    The paper emphasizes the main changes of the mechanical and electrical properties of some organic insulating materials exposed to accelerated electron beams. These materials are liable to be used in nuclear plants and particle accelerators. The principal mechanical and electrical properties analyzed were: tensile strength, fracture strength, tearing on fracture, dielectric strength, electrical resistivity, dielectric constant and tangent angle of dielectric losses. (authors)