Science.gov

Sample records for ring beam losses

  1. Beam Loss Monitors for NSLS-II Storage Ring

    SciTech Connect

    Kramer, S.L.; Cameron, P.

    2011-03-28

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

  2. Beam Loss Control for the NSLS-II Storage Ring

    SciTech Connect

    Kramer, S.L.; Choi, J.

    2011-03-28

    The shielding design for the NSLS-II storage ring is designed for the full injected beam losses in two periods of the ring around the injection point, but for the remainder of the ring its shielded for {le} 10% top-off injection beam. This will require a system to insure that beam losses do not exceed these levels for time sufficient to cause excessive radiation exposure outside the shield walls. This beam Loss Control and Monitoring (LCM) system will control the beam losses to the more heavily shielded injection region while monitoring the losses outside this region. To achieve this scrapers are installed in the injection region to intercept beam particles that might be lost outside this region. The scrapers will be thin (< 1Xrad) that will allow low energy electrons to penetrate and the subsequent dipole will separate them from the stored beam. These thin scrapers will reduce the radiation from the scraper compared to thicker scrapers. The dipole will provide significant local shielding for particles that hit inside the gap and a source for the loss monitor system that will measure the amount of beam lost in the injection region.

  3. Analysis ob beam losses at PSR (Proton Storage Ring)

    SciTech Connect

    Macek, R.J.; Fitzgerald, D.H.; Hutson, R.L.; Plum, M.A.; Thiessen, H.A.

    1988-01-01

    Beam losses and the resulting component activation at the Los Alamos Proton Storage Ring (PSR) have limited operating currents to about 30..mu..A average at a repetition rate of 15 Hz. Loss rates were found to be approximately proportional to the circulating current and can be understood by a detailed accounting of emittance growth in the two step injection process along with Coulomb scattering of the stored beam during multiple traversals of the injection foil. Calculations and simulations of the losses are in reasonable agreement with measurements.

  4. Recording PEP2 Ring Beam Losses at SLAC

    SciTech Connect

    Zelazny, M.; Gromme, T.; Himel, T.; Hendrickson, L.; Krauter, K.; /SLAC

    2005-09-30

    The PEP2 (e+)(e-) storage rings contain many complex interrelated systems. When the beam aborts, examining a record of the orbit from the time just before the abort can help identify the root cause. At the Stanford Linear Accelerator Center (SLAC) a system has been developed to continuously record beam orbits from Beam Position Monitors (BPMS) into a circular buffer. When the beam is aborted the buffers are frozen and their contents are stored for later analysis. BPM orbits are saved on a turn by turn basis for 2800 turns in both the high energy ring (HER) and the low energy ring (LER). Each BPM Processor (BPMP) can either monitor the HER or the LER, but not both as the readout of the two rings is multiplexed into a single readout channel. Tools exist as part of the SLAC Control Program (SCP) to collect, display, and save the data. A physicist or operator can choose a few BPMS in which to view all 2800 turns to identify the turn in which the beam went awry; then ask for that specific orbit from all of the BPMS in the storage ring to determine the root cause of the abort.

  5. Beam Loss due to Foil Scattering in the SNS Accumulator Ring

    SciTech Connect

    Holmes, Jeffrey A; Plum, Michael A

    2012-01-01

    In order to better understand the contribution of scattering from the primary stripper foil to losses in the SNS ring, we have carried out calculations using the ORBIT Code aimed at evaluating these losses. These calculations indicate that the probability of beam loss within one turn following a foil hit is ~1.8 10-8 , where is the foil thickness in g/cm2, assuming a carbon foil. Thus, for a typical SNS stripper foil of thickness = 390 g/cm2, the probability of loss within one turn of a foil hit is ~7.0 10-6. This note describes the calculations used to arrive at this result, presents the distribution of these losses around the SNS ring, and compares the calculated results with observed ring losses for a well-tuned production beam.

  6. Three-dimensional particle trajectories and waste beam losses in injection dump beam line of SNS accumulator ring

    SciTech Connect

    Wang, Jian-Guang; Plum, Michael A

    2008-01-01

    The SNS ring injection dump beam line has been suffering high beam losses since its commissioning. In order to understand the mechanisms of the beam losses, we have performed 3D simulation studies of the beam line. The 3D models consist of three injection chicane dipoles and one injection dump septum magnet. 3D particle trajectories in the models are computed. We then extend particle optics calculations to the injection dump. Our studies have clearly shown some design and operation problems, that cause beam losses in the injection dump beam line. These include incorrect chicane dipole settings, incorrect position of a chicane dipole, too small aperture of injection dump septum, and inadequate focusing downstream. This paper reports our findings and the remedies to the injection beam loss problems.

  7. BEAM-LOSS DRIVEN DESIGN OPTIMIZATION FOR THE SPALLATION NEUTRON SOURCE (SNS) RING.

    SciTech Connect

    WEI,J.; BEEBE-WANG,J.; BLASKIEWICZ,M.; CAMERON,P.; DANBY,G.; GARDNER,C.J.; JACKSON,J.; LEE,Y.Y.; LUDEWIG,H.; MALITSKY,N.; RAPARIA,D.; TSOUPAS,N.; WENG,W.T.; ZHANG,S.Y.

    1999-03-29

    This paper summarizes three-stage 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.).

  8. Beam loss

    NASA Astrophysics Data System (ADS)

    VanGinneken, A.; Edwards, D.; Harrison, M.

    1989-04-01

    This paper presents results from simulations of beam losses during the operation of a superconducting accelerator. The calculations use a combination of hadron/electromagnetic cascade plus elastic scattering codes with accelerator tracking routines. These calculations have been used in conjunction with the design of the Fermilab Tevatron. First accelerator geometry is described. The rest of the paper discusses a detailed attempt to simulate a fast extraction cycle, essentially in chronological order. Beginning with an unperturbed beam, the simulation generates proton phase-space distributions incident on the electrostatic septum. These interact either elastically or inelastically with the septum wires, and the products of these interactions are traced through the machine. Where these leave the accelerator, energy deposition levels in the magnets are calculated together with the projected response of the beam-loss monitors in this region. Finally, results of the calculation are compared with experimental data. (AIP)

  9. Stripper-foil scan studies of the first-turn beam loss mechanism in the LAMPF proton storage ring (PSR)

    SciTech Connect

    Hutson, R.: Fitzgerald, D.; Frankle, S.; Macek, R.; Plum, M.; Wilkinson, C.

    1993-01-01

    First-turn beam losses in the LAMPF Proton Storage Ring were measured as a function of the left-right position of the carbon foil used to strip neutral hydrogen atoms to H[sup +] for proton injection into the PSR. Two foil thicknesses, 200 and 300 [mu]g/cm[sup 2], were tested. Results indicated that first-turn loss is caused predominately by magnetic field stripping of a small fraction of the H[sub 0] atoms that pass through the stripper foil without being stripped to protons, and the results were not consistent with a mechanism involving protons originating from atoms in the halo of the neutral beam incident on the stripper foil.

  10. Stripper-foil scan studies of the first-turn beam loss mechanism in the LAMPF proton storage ring (PSR)

    SciTech Connect

    Hutson, R.: Fitzgerald, D.; Frankle, S.; Macek, R.; Plum, M.; Wilkinson, C.

    1993-06-01

    First-turn beam losses in the LAMPF Proton Storage Ring were measured as a function of the left-right position of the carbon foil used to strip neutral hydrogen atoms to H{sup +} for proton injection into the PSR. Two foil thicknesses, 200 and 300 {mu}g/cm{sup 2}, were tested. Results indicated that first-turn loss is caused predominately by magnetic field stripping of a small fraction of the H{sub 0} atoms that pass through the stripper foil without being stripped to protons, and the results were not consistent with a mechanism involving protons originating from atoms in the halo of the neutral beam incident on the stripper foil.

  11. CEBAF beam loss accounting

    SciTech Connect

    Ursic, R.; Mahoney, K.; Hovater, C.; Hutton, A.; Sinclair, C.

    1995-12-31

    This paper describes the design and implementation of a beam loss accounting system for the CEBAF electron accelerator. This system samples the beam curent throughout the beam path and measures the beam current accurately. Personnel Safety and Machine Protection systems use this system to turn off the beam when hazardous beam losses occur.

  12. BEAM INSTRUMENTATION FOR THE SPALLATION NEUTRON SOURCE RING.

    SciTech Connect

    WITKOVER,R.L.; CAMERON,P.R.; SHEA,T.J.; CONNOLLY,R.C.; KESSELMAN,M.

    1999-03-29

    The Spallation Neutron Source (SNS) will be constructed by a multi-laboratory collaboration with BNL responsible for the transfer lines and ring. [1] 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{sup -4}. A Beam-In-Gap (BIG) monitor is being designed to assure out-of-bucket beam will not be lost in the ring.

  13. Preliminary comments about beam loss

    SciTech Connect

    Groom, D.

    1985-10-01

    A variety of beam loss questions are being investigated. They affect several design issues, ranging from machine-associated background in the detectors to the radiation lifetime of the main-ring magnets: (1) Muons. Oppositely directed muon beams from prompt muon production, primary meson decay, and a variety of other processes radiate from each IR. If they were not fanned by the insertion dipoles, the beams would be sufficiently intense and energetic that they would present a radiation hazard even after penetrating 2 km of soil or rock. (2) Machine-associated background in the IR`s. About 30 mb of the total cross section is elastic or quasi-elastic, and most of the protons are in a Gaussian spot with sigma = 9 mr. These particles are well within the machine acceptance, but there is a grey area in the tail of the distributions in which the scattered particles `almost` remain in orbit - they continue for some distance but eventually hit a wall. (3) Cryogenic load. This problem has been addressed to some degree in the RDS, but considerably more detail is needed. It appears that a very large fraction of the inelastic particle energy will be deposited here. (4) Radiation damage in the ring. The lifetime of both magnets and electronics in the tunnel might be limited by radiation due to particle loss. Early results are not reassuring. Tevatron measurements, reported to the authors by John Elias, indicate that most of the tunnel background comes from particle loss due to beam-gas collisions.

  14. eRHIC ring-ring design with head-on beam-beam compensation

    SciTech Connect

    Montag,C.; Blaskiewicz, M.; Pozdeyev, E.; Fischer, W.; MacKay, W. W.

    2009-05-04

    The luminosity of the eRHIC ring-ring design is limited by the beam-beam effect exerted on the electron beam. Recent simulation studies have shown that the beam-beam limit can be increased by means of an electron lens that compensates the beam-beam effect experienced by the electron beam. This scheme requires proper design of the electron ring, providing the correct betatron phase advance between interaction point and electron lens. We review the performance of the eRHIC ring-ring version and discuss various parameter sets, based on different cooling schemes for the proton/ion beam.

  15. Beam diagnostics at high-intensity storage rings

    SciTech Connect

    Plum, M.

    1993-11-01

    Beam diagnostics at high-intensity facilities feature their own special set of problems and characteristics. Issues peculiar to high-intensity storage rings include beam loss, beam halos, extraction efficiency, beam in the gap, clearing electrodes, and beam-profile measurement. The Los Alamos Proton Storage Ring (PSR) is a nice example of a high-intensity storage ring. The author discusses in some detail three diagnostic systems currently in use at the PSR: the beam-loss-monitor system, the electron-clearing system, and the beam-in-the-gap monitor. Much of the discussion is inspired by the problems that were encountered and the useful things learned while commissioning and developing the PSR. Another inspiration is the work on the next-generation neutron-spallation source, also known as the National Center for Neutron Research (NCNR).

  16. Beam diagnostics at high-intensity storage rings

    SciTech Connect

    Plum, M. )

    1994-10-10

    Beam diagnostics at high-intensity facilities feature their own special set of problems and characteristics, issues peculiar to high-intensity storage rings include beam loss, beam halos, extraction efficiency, beam in the gap, clearing electrodes, and beam-profile measurement. The Los Alamos Proton Storage Ring (PSR) is a nice example of a high-intensity storage ring. I will discuss in some detail three diagnostic systems currently in use at the PSR: the beam-loss-monitor system, the electron-clearing system, and the beam-in-the-gap monitor. Much of our discussion is inspired by the problems we have encountered and the useful things we have learned while commissioning and developing the PSR. Another inspiration is our work on the next-generation neutron-spallation source, also known as the National Center for Neutron Research (NCNR).

  17. BEAM LOSS MECHANISMS IN HIGH INTENSITY LINACS

    SciTech Connect

    Plum, Michael A

    2012-01-01

    In the present operation of the Oak Ridge Spallation Neutron Source, 60-Hz, 825-us H beam pulses are accelerated to 910 MeV, and then compressed to less than a microsecond in the storage ring, to deliver 1 MW of beam power to the spallation target. The beam loss in the superconducting portion of the linac is higher than expected, and it has shown a surprising counter-intuitive correlation with quadrupole magnetic fields, with a loss minimum occurring when the quadrupoles are set to approximately half their design values. This behavior can now be explained by a recent set of experiments that show the beam loss is primarily due to intra-beam stripping. Beam halo is another important beam loss contributor, and collimation in the 2.5 MeV Medium Energy Beam Transport has proven to be an effective mitigation strategy. In this presentation, we will summarize these and other beam loss mechanisms that are important for high intensity linacs.

  18. RHIC BEAM LOSS MONITOR SYSTEM INITIAL OPERATION.

    SciTech Connect

    WITKOVER,R.L.; MICHNOFF,R.J.; GELLER,J.M.

    1999-03-29

    The RHIC Beam Loss Monitor (BLM) System is designed to prevent beam loss quenching of the superconducting magnets, and acquire loss data. Four hundred ion chambers are located around the rings to detect losses. The required 8-decade range in signal current is compressed using an RC pre- integrator ahead of a low current amplifier. A beam abort may be triggered if fast or slow losses exceed programmable threshold levels. A micro-controller based VME module sets references and gains and reads trip status for up to 64 channels. Results obtained with the detectors in the RHIC Sextant Test and the prototype electronics in the AGS-to-RHIC (AtR) transfer line are presented along with the present status of the system.

  19. Time Evolution of Beam in the Recycler Ring

    SciTech Connect

    Krish Gounder, John Marriner and Shekhar Mishra

    2003-05-07

    We study the time evolution of the beam current in the Fermilab Recycler Ring due to abrupt physical processes (single coulomb scattering, nuclear scattering) that cause sudden loss of beam, and diffusive processes (multiple coulomb scattering, lattice dependence, etc.) which cause emittance growth. This emittance growth combined with finite aperture of the beam pipe will lead to eventual loss of most beam. We develop a fitting technique to the time evolution of beam current to estimate emittance growth. Finally we compare the directly measured growth with the fitted value.

  20. A storage ring for radioactive beams

    SciTech Connect

    Moltz, D.M.

    1994-05-01

    Preliminary ideas are presented for the scientific justification of a storage ring for radioactive beams. This storage ring would be suitable for many nuclear and atomic physics experiments. Ideally, it would be constructed and tested at an existing low-energy heavy-ion facility before relocation to a major radioactive beam facility.

  1. Measurements of aperture and beam lifetime using movable beam scrapers in Indus-2 electron storage ring

    SciTech Connect

    Kumar, Pradeep; Ghodke, A. D.; Karnewar, A. K.; Holikatti, A. C.; Yadav, S.; Puntambekar, T. A.; Singh, G.; Singh, P.

    2013-12-15

    In this paper, the measurements of vertical and horizontal aperture which are available for stable beam motion in Indus-2 at beam energy 2.5 GeV using movable beam scrapers are presented. These beam scrapers are installed in one of the long straight sections in the ring. With the movement of beam scrapers towards the beam centre, the beam lifetime is measured. The beam lifetime data obtained from the movement of vertical and horizontal beam scrapers are analyzed. The contribution of beam loss due to beam-gas scattering (vacuum lifetime) and electron-electron scattering within a beam bunch (Touschek lifetime) is separated from the measured beam lifetime at different positions of the beam scrapers. Vertical and horizontal beam sizes at scrapers location are estimated from the scraper movement towards the beam centre in quantum lifetime limit and their values closely agree with measured value obtained using X-ray diagnostic beamline.

  2. Beam Loss Monitoring for LHC Machine Protection

    NASA Astrophysics Data System (ADS)

    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.

  3. Polarisation losses in a ring prism cavity

    SciTech Connect

    Kuryatov, V N; Sokolov, A L

    2000-02-28

    The polarisation losses in a ring cavity, formed by total-internal-reflection prisms, were analysed. All the sources of the polarisation losses are indicated and expressions for their calculation are presented. The limit to loss reduction in cavities of this kind, set by the difference between the radii of curvature of the radiation wavefront and of the refracting prism faces, was determined. (laser gyroscopes)

  4. RHIC low energy beam loss projections

    SciTech Connect

    Satogata,T.

    2009-08-01

    For RHIC low-energy operations, we plan to collide Au beams with energies of E = 2:5-10 GeV/u in RHIC. Beams are injected into collision optics, and RHIC runs as a storage ring with no acceleration. At these low energies, observed beam lifetimes are minutes, with measured beam lifetimes of 3.5 min (fast) and 50 min (slow) at E=4.6 GeV/u in the March 2008 test run. With these lifetimes we can operate RHIC as a storage ring to produce reasonable integrated luminosity. This note estimates beam losses and collimator/dump energy deposition in normal injection modes of low energy operation. The main question is whether a normal injection run is feasible for an FY10 10-15 week operations run from a radiation safety perspective. A peripheral question is whether continuous injection operations is feasible from a radiation safety perspective. In continuous injection mode, we fill both rings, then continuously extract and reinject the oldest bunches that have suffered the most beam loss to increase the overall integrated luminosity. We expect to gain a factor of 2-3 in integrated luminosity from continuous injection at lowest energies if implemented[1]. Continuous injection is feasible by FY11 from an engineering perspective given enough effort, but the required extra safety controls and hardware dose risk make it unappealing for the projected luminosity improvement. Low-energy electron cooling will reduce beam losses by at least an order of magnitude vs normal low-energy operations, but low energy cooling is only feasible in the FY13 timescale and therefore beyond the scope of this note. For normal injection low energy estimates we assume the following: (1) RHIC beam total energies are E=2.5-10 GeV/u. (Continuous injection mode is probably unnecessary above total energies of E=7-8 GeV/u.); (2) RHIC operates only as a storage ring, with no acceleration; (3) 110 bunches of about 0.5-1.0 x 10{sup 9} initial bunch intensities (50-100% injection efficiency, likely conservative

  5. Beam Diagnostics of the Small Isochronous Ring

    SciTech Connect

    Felix Marti; Eduard Pozdeyev

    2004-07-01

    The purpose of this paper is to describe the beam diagnostic systems in the Small Isochronous Ring (SIR) developed and built at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). SIR is a small-scale experiment that simulates the dynamics of intense beams in large accelerators. A 20 to 30 keV hydrogen or deuterium ion bunch is injected in the ring, extracted after a variable number of turns and its longitudinal profile is studied. Some of the diagnostic tools available in SIR include an emittance measurement system in the injection line, scanning wires in different sections of the ring, phosphor screens at the injection and extraction points and a fast Faraday cup in the extraction line. The design of these systems and the kind of beam information they provide are discussed in detail.

  6. Beam stability issues of the VLHC rings

    SciTech Connect

    K.-Y. Ng

    2001-05-08

    Beam stability issues of the VLHC rings in Phase 1 and Phase 2 are reviewed. For accelerator rings of circumference 232 km and beam pipe radius of the order of 1 cm, the impedance of the vacuum chamber is dominated by the resistive wall. The most dangerous instabilities are the single-bunch transverse mode coupling instability and the transverse coupled bunch instability driven by the resistive wall at sub-revolution frequency. Scaling is studied concerning the thresholds of these instabilities and the dominance of the resistive wall impedance as the size of the accelerator increases.

  7. Storage rings for radioactive ion beams

    NASA Astrophysics Data System (ADS)

    Nolden, F.; Dimopoulou, C.; Dolinskii, A.; Steck, M.

    2008-10-01

    Storage rings for radioactive heavy ions can be applied for a wide range of experiments in atomic and nuclear physics. The rare isotope beams are produced in flight via fragmentation or fission of high-intensity primary ions and they circulate in the storage ring at moderately relativistic energies (typically between 0.1 GeV/u up to 1 GeV/u). Due to their production mechanism they are usually highly charged or even fully stripped. The circulating radioactive heavy ion beams can be used to measure nuclear properties such as masses and decay times, which, in turn, can depend strongly on the ionic charge state. The storage rings must have large acceptances and dynamic apertures. The subsequent application of stochastic precooling of the secondary ions which are injected with large transverse and longitudinal emittances, and electron cooling to reach very high phase space densities has turned out to be a helpful tool for experiments with short-lived ions having lifetimes down to a few seconds. Some of these experiments have already been performed at the experimental storage ring ESR at GSI. The storage ring complex of the FAIR project is intended to enhance significantly the range of experimental possibilities. It is planned to extend the scope of experimental possibilities to collisions with electron or antiproton beams.

  8. Comparison of beam transport simulations to measurements at the Los Alamos Proton Storage Ring

    SciTech Connect

    Wilkinson, C.; Neri, F.; Fitzgerald, D.H.; Blind, B.; Macek, R.; Plum, M.; Sander, O.; Thiessen, H.A.

    1997-10-01

    The ability to model and simulate beam behavior in the Proton Storage Ring (PSR) of the Los Alamos Neutron Science Center (LANSCE) is an important diagnostic and predictive tool. This paper gives the results of an effort to model the ring apertures and lattice and use beam simulation programs to track the beam. The results are then compared to measured activation levels from beam loss in the ring. The success of the method determines its usefulness in evaluating the effects of planned upgrades to the Proton Storage Ring.

  9. Studies of Beam Dynamics in Cooler Rings

    SciTech Connect

    Dietrich, J.; Stein, J.; Meshkov, I.; Sidorin, A.; Smirnov, A.

    2006-03-20

    This report describes the numerical simulation of the crystalline proton beam formation in COSY using BETACOOL code. The study includes the description of experimental results at NAP-M storage ring where the large reduction of the momentum spread was observed for first time. The present simulation shows that this behavior of proton beam can not be explained as ordered state of protons. The numerical simulation of crystalline proton beams was done for COSY parameters. The number of protons when the ordering state can be observed is limited by value 106 particles and momentum spread less then 10-6. Experimental results for the attempt to achieve of ordered state of proton beam for COSY is presented. This work is supported by RFBR grant no. 05-02-16320 and INTAS grant no. 03-54-5584.

  10. Coherent parasitic energy loss of the recycler beam

    SciTech Connect

    K.Y. Ng

    2004-07-14

    Parasitic energy loss of the particle beam in the Recycler Ring is discussed. The long beam confined between two barrier waves has a spectrum that falls off rapidly with frequency. Discrete summation over the revolution harmonics must be made to obtain the correct energy loss per particle per turn, because only a few lower revolution harmonics of real part of the longitudinal impedance contribute to the parasitic energy loss. The longitudinal impedances of the broadband rf cavities, the broadband resistive-wall monitors, and the resistive wall of the vacuum chamber are discussed. They are the main sources of the parasitic energy loss.

  11. BEAM-BEAM SIMULATIONS FOR THE ERHIC ELECTRON RING.

    SciTech Connect

    MONTAG, C.

    2005-05-16

    To study collisions between polarized electrons and heavy ions or polarized protons at high energy, adding a 10 GeV electron storage ring to the existing RHIC facility is currently under consideration. To achieve high luminosities of several 10{sup 33} cm{sup -2} sec{sup -1} range, a vertical beam-beam tuneshift parameter of {zeta}{sub y} = 0.08 is required for the electron beam. Simulation studies are being performed to study the feasibility of this high tuneshift parameter and explore the potential for even higher tuneshifts. Recent results of these studies are presented.

  12. Simulation of loss of uranium ions due to charge changing processes in the CSRm ring

    NASA Astrophysics Data System (ADS)

    Zheng, Wen-Heng; Yang, Jian-Cheng; Li, Peng; Li, Zhong-Shan; Shang, Peng; Qu, Guo-Feng; Ge, Wen-Wen; Tang, Mei-Tang; Sha, Xiao-Ping

    2015-04-01

    Significant beam loss caused by the charge exchange processes and ion impact-induced outgassing may restrict the maximum number of accelerated heavy ions during the high intensity operation of an accelerator. In order to control beam loss due to charge exchange processes and confine the generated desorption gas, tracking of the beam loss distribution and installation of absorber blocks with low-desorption rate material at appropriate locations in the main Cooler Storage Ring (CSRm) at the Institute of Modern Physics, Lanzhou, will be performed. The loss simulation of uranium ions with electron-loss is presented in this report and the conclusion is that most charge changed particles are lost in the second dipole of the super-period structure. The calculation of the collimation efficiency of the CSRm ring will be continued in the future. Supported by National Natural Science Foundation of China (11305227)

  13. A Beam Transport and Loss simulation with electrostatic beam separator

    NASA Astrophysics Data System (ADS)

    Yang, Ming-Jen

    1997-05-01

    Eletrostatic beam separator (septa) string is used in the Fermilab fixed target program for slow extraction from Tevatron and for dividing the beam to different experimental area. The loss from beam interaction with the dividing wire plane of the septa is used to determine the alignment of individual septum within a string of many. The interpretation of the real life signal registered at the loss monitors is not always straight forward. A simulation is being done to model the beam split through septa string and the loss pattern at exisiting beam loss monitor locations. This should lead to a better understanding of the signal and help in the alignment operation.

  14. DATA ACQUISITION FOR SNS BEAM LOSS MONITOR SYSTEM

    SciTech Connect

    YENG,Y.GASSNER,D.HOFF,L.WITKOVER,R.

    2003-10-13

    The Spallation Neutron Source (SNS) beam loss monitor system uses VME based electronics to measure the radiation produced by lost beam. Beam loss signals from cylindrical argon-filled ion chambers and neutron detectors will be conditioned in analog front-end (AFE) circuitry. These signals will be digitized and further processed in a dedicated VME crate. Fast beam inhibit and low-level, long-term loss warnings will be generated to provide machine protection. The fast loss data will have a bandwidth of 35kHz. While the low level, long-term loss data will have much higher sensitivity. This is further complicated by the 3 decade range of intensity as the Ring accumulates beam. Therefore a bandwidth of 100kHz and dynamic range larger than 21 bits data acquisition system will be required for this purpose. Based on the evaluation of several commercial ADC modules in preliminary design phase, a 24 bits Sigma-Delta data acquisition VME bus card was chosen as the SNS BLM digitizer. An associated vxworks driver and EPICS device support module also have been developed at BNL. Simulating test results showed this system is fully qualified for both fast loss and low-level, long-term loss application. The first prototype including data acquisition hardware setup and EPICS software (running database and OPI clients) will be used in SNS Drift Tube Linac (DTL) system commissioning.

  15. Ring Current Ion Losses by Pitch Angle Scattering

    NASA Astrophysics Data System (ADS)

    Walt, M.; Voss, H. D.

    2001-12-01

    The Source/Loss Cone Energetic Particle Spectrometer (SEPS) on the Polar Satellite observes ions above 155 keV with an angular resolution of about 1.5 degrees. When the axis of SEPS is pointing within 10 degrees of the magnetic field direction, the detector measures particles in both the downward and upward loss cones. Measurements of the loss cone fluxes during the magnetic storms of August 6, 1998, August 27, 1998, September 25, 1998, October 19, 1998, and November 13, 1998 often show large fluxes of ring current ions moving downward inside the loss cone. At times these fluxes are comparable to the trapped ion population, indicating that strong pitch angle scattering is taking place at least locally. Although Polar encounters the ring current region at only two magnetic local times during any given storm, the frequent observation of precipitation suggests that pitch angle scattering is an important loss mechanism for ring current ions.

  16. Beam storage studies in the Fermilab main ring

    SciTech Connect

    MacLachlan, J.A.

    1982-05-06

    Bunched beams of 100 and 150 GeV have been stored in the Fermilab Main Ring for periods of up to one hour. The observations of beam current and beam profiles are analyzed for the effects of gas scattering, chromaticity and non-linear magnetic field.

  17. Beam-storage studies in the Fermilab main ring

    SciTech Connect

    MacLachlan, J.A.

    1982-05-06

    Bunched beams of 100 and 150 GeV have been stored in the Fermilab Main Ring for periods of up to one hour. The observations of beam current and beam profiles are analyzed for the effects of gas scattering, chromaticity and non-linear magnetic field.

  18. Collider ring particle loss tracking with SSCTRK

    SciTech Connect

    Garavaglia, T.; Kauffmann, S.K.; Stiening, R.

    1990-04-01

    The SSCTRK numerical simulation tracking code has been used to study the benefit of increasing the SSC dipole magnet aperture from 4 to 5 cm. This study has been carried out for both hypothetical highly corrected and plausibly corrected machines, the former having no systematic multipole errors and chromaticity identically zero. The choice of tune values, phase advance per cell, random multipole errors, systematic multipole errors and chromaticity (for the plausibly corrected machines), closed orbit error, the criterion for particle loss, etc. are set forth in detail. Runs of 10{sup 5} turns and 3 {times} 10{sup 6} turns are presented together with the approximate dynamic apertures they yield from their particle loss patterns.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  20. A new method for beam stacking in storage rings

    SciTech Connect

    Bhat, C.M.; /Fermilab

    2008-06-01

    Recently, I developed a new beam stacking scheme for synchrotron storage rings called 'longitudinal phase-space coating' (LPSC). This scheme has been convincingly validated by multi-particle beam dynamics simulations and has been demonstrated with beam experiments at the Fermilab Recycler. Here, I present the results from both simulations and experiments. The beam stacking scheme presented here is the first of its kind.

  1. Longitudinal stabilisation of bunched beams in a FEL storage ring

    NASA Astrophysics Data System (ADS)

    Migliorati, M.; Palumbo, L.; Dattoli, G.; Mezi, L.; Renieri, A.; Voykov, G. K.

    1997-02-01

    Experimental observations on FEL Storage Rings (Aco, Super-Aco, VEPP3, TERAS) have shown that in a storage ring with an operating FEL there is a mutual effect between the FEL operational mode and the beam longitudinal distribution. The main effects are the birth of a macro-temporal structure of the FEL radiation and a suppression of the synchrotron sidebands, evidence of beam stabilisation against the microwave instabilities. In this paper we discuss the main features of the beam dynamics analysed with a simulation code recently developed, which includes the FEL-beam interaction. Furtherly, we propose an heuristic model which enable to describe in a simple way the overall system.

  2. Beam dynamics of CANDLE storage ring low alpha operation

    NASA Astrophysics Data System (ADS)

    Sargsyan, A.; Amatuni, G.; Sahakyan, V.; Tsakanov, V.; Zanyan, G.

    2015-10-01

    The generation of the coherent THz radiation and short pulse synchrotron radiation in dedicated electron storage rings requires the study of non-standard magnetic lattices which provide low momentum compaction factor (alpha) of the ring. In the present paper two low alpha operation lattices based on modification of the original beam optics and implementation of inverse bend magnets are studied for CANDLE storage ring. For considered cases an analysis of transverse and longitudinal beam dynamics is given and the feasibility of lattices is discussed.

  3. Spallation neutron source beam loss monitor system

    NASA Astrophysics Data System (ADS)

    Gassner, D.; Witkover, R.; Cameron, P.; Power, J.

    2000-11-01

    The Spallation Neutron Source facility to be built at ORNL is designed to accumulate 2×1014 protons at 1.0 GeV and deliver them to the experimental target in one bunch at 60 Hz. To achieve this goal and protect the machine from excessive radiation activation, an uncontrolled loss criteria of 1 part in 104 (1 W/m) has been specified. Measured losses will be conditioned to provide machine tuning data, a beam abort trigger, and logging of loss history. The design of the distributed loss monitor system utilizing argon-filled glass ionization chambers and scintillator-photomultipliers will be presented.

  4. Neutral Beam Ion Loss Modeling for NSTX

    SciTech Connect

    D. Mikkelsen; D.S. Darrow; L. Grisham; R. Akers; S. Kaye

    1999-06-01

    A numerical model, EIGOL, has been developed to calculate the loss rate of neutral beam ions from NSTX and the resultant power density on the plasma facing components. This model follows the full gyro-orbit of the beam ions, which can be a significant fraction of the minor radius. It also includes the three-dimensional structure of the plasma facing components inside NSTX. Beam ion losses from two plasma conditions have been compared: {beta} = 23%, q{sub 0} = 0.8, and {beta} = 40%, q{sub 0} = 2.6. Global losses are computed to be 4% and 19%, respectively, and the power density on the rf antenna is near the maximum tolerable levels in the latter case.

  5. RHIC beam loss monitor system design

    SciTech Connect

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

    1997-07-01

    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.

  6. COMPUTATIONAL BEAM DYNAMICS STUDIES FOR IMPROVING THE RING INJECTION AND EXTRACTION SYSTEMS IN SNS

    SciTech Connect

    Holmes, Jeffrey A; Cousineau, Sarah M; Plum, Michael A; Wang, Jian-Guang

    2008-01-01

    The ring injection and extraction systems must function as designed in order for the Spallation Neutron Source (SNS) to achieve its specified performance. In commissioning and early operations we have encountered problems that have been traced to these systems. We experienced high beam losses in and around the injection dump, the rectification of which has necessitated ongoing study and development by a multidisciplinary team. Results already include a number of enhancements of existing features and the addition of new elements and diagnostics. The problem in the extraction region stems from tilted beam distributions observed in the ring-to-target beam transport line (RTBT) and on the target, thus complicating the control of the beam-on-target distribution. This indicates the inadvertent introduction of x-y beam coupling somewhere upstream of the RTBT. The present paper describes computational studies, using the ORBIT Code, addressed at the detailed understanding and solution of these problems.

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

    SciTech Connect

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

    2011-03-28

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

  8. The ATLAS Beam Condition and Beam Loss Monitors

    NASA Astrophysics Data System (ADS)

    Dolenc, I.

    2010-04-01

    The primary goal of ATLAS Beam Condition Monitor (BCM) and Beam Loss Monitor (BLM) is to protect the ATLAS Inner Detector against damaging LHC beam incidents by initiating beam abort in case of beam failures. Poly-crystalline Chemical Vapour Deposition (pCVD) diamond was chosen as the sensor material for both systems. ATLAS BCM will provide real-time monitoring of instantaneous particle rates close to the interaction point (IP) of ATLAS spectrometer. Using fast front-end and signal processing electronics the time-of-flight and pulse amplitude measurements will be performed to distinguish between normal collisions and background events due to natural or accidental beam losses. Additionally, BCM will also provide coarse relative luminosity information. A second system, the ATLAS BLM, is an independent system which was recently added to complement the BCM. It is a current measuring system and was partially adopted from the BLM system developed by the LHC beam instrumentation group with pCVD diamond pad sensors replacing the ionisation chambers. The design of both systems and results of operation in ATLAS framework during the commissioning with cosmic rays will be reported in this contribution.

  9. Losses of ring current ions by strong pitch angle scattering

    NASA Astrophysics Data System (ADS)

    Walt, M.; Voss, H. D.

    High angular resolution measurements of 155 keV ions in the ring current during the magnetic storm of August 6, 1998 show filled loss cones indicating that very rapid pitch angle scattering is taking place above the satellite location. The measurements were made with the SEPS detector on the Polar satellite during its passages through the ring current regions, usually at magnetic latitudes near ±45° and at magnetic local times of about 04:00 and 16:00 hrs. The observed strong pitch angle scattering implies a trapping lifetime of less than an hour and may explain the early rapid recovery of Dst during magnetic storms.

  10. Coupled beam motion in a storage ring with crab cavities

    NASA Astrophysics Data System (ADS)

    Huang, Xiaobiao

    2016-02-01

    We studied the coupled beam motion in a storage ring between the transverse and longitudinal directions introduced by crab cavities. The analytic form of the linear decoupling transformation is derived. The equilibrium bunch distribution in an electron storage ring with a crab cavity is given, including contribution to the eigenemittance induced by the crab cavity. Application to the short pulse generation scheme using crab cavities is considered.

  11. Coupled beam motion in a storage ring with crab cavities

    SciTech Connect

    Huang, Xiaobiao

    2015-11-16

    We studied the coupled beam motion in a storage ring between the transverse and longitudinal directions introduced by crab cavities. Analytic form of the linear decoupling transformation is derived. Also, the equilibrium bunch distribution in an electron storage ring with a crab cavity is given, including contribution to the eigen-emittance induced by the crab cavity. Application to the short pulse generation scheme using crab cavities [1] is considered.

  12. Online optimization of storage ring nonlinear beam dynamics

    NASA Astrophysics Data System (ADS)

    Huang, Xiaobiao; Safranek, James

    2015-08-01

    We propose to optimize the nonlinear beam dynamics of existing and future storage rings with direct online optimization techniques. This approach may have crucial importance for the implementation of diffraction limited storage rings. In this paper considerations and algorithms for the online optimization approach are discussed. We have applied this approach to experimentally improve the dynamic aperture of the SPEAR3 storage ring with the robust conjugate direction search method and the particle swarm optimization method. The dynamic aperture was improved by more than 5 mm within a short period of time. Experimental setup and results are presented.

  13. Complex ABCD transformations for optical ring cavities with losses and gain

    SciTech Connect

    Kudashov, V N; Radin, A M; Plachenov, A B

    1999-04-30

    Complex ABCD field transformations are investigated for inhomogeneous optical ring cavities with losses and gain. It is shown that the sets of eigenfunctions, corresponding to counterpropagating waves, are really biorthogonal: the functions in each of these sets are really orthogonal relative to one another, and have a complex weighting factor independent of the mode number. Bidirectional and unidirectional stability conditions are formulated for such cavities. These conditions are qualitatively different from those for loss-free cavities. A simple algorithm is proposed for the evaluation of the ABCD matrix for a medium with an arbitrary longitudinal inhomogeneity along the beam. (laser applications and other topics in quantum electronics)

  14. The AGS Booster beam loss monitor system

    SciTech Connect

    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 {times} 10{sup 13} protons and carbon to gold ions at 50-3 {times} 10{sup 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.

  15. Beam dynamics in an ultra-low energy storage rings (review of existing facilities and feasibility studies for future experiments)

    NASA Astrophysics Data System (ADS)

    Papash, A. I.; Smirnov, A. V.; Welsch, C. P.

    2014-03-01

    Storage rings operating at ultra-low energies and in particular electrostatic storage rings have proven to be invaluable tools for atomic and molecular physics. Due to the mass independence of the electrostatic rigidity, these machines are able to store a wide range of different particles, from light ions to heavy singly charged bio-molecules. However, earlier measurements showed strong limitations on beam intensity, fast decay of ion current, reduced life time etc. The nature of these effects was not fully understood. Also a large variety of experiments in future generation ultra-low energy storage and decelerator facilities including in-ring collision studies with a reaction microscope require a comprehensive investigation of the physical processes involved into the operation of such rings. In this paper, we present review of non-linear and long term beam dynamics studies on example of the ELISA, AD Recycler, TSR and USR rings using the computer codes BETACOOL, OPERA-3D and MAD-X. The results from simulations were benchmarked against experimental data of beam losses in the ELISA storage ring. We showed that decay of beam intensity in ultra-low energy rings is mainly caused by ion losses on ring aperture due to multiple scattering on residual gas. Beam is lost on ring aperture due to small ring acceptance. Rate of beam losses increases at high intensities because of the intra-beam scattering effect adds to vacuum losses. Detailed investigations into the ion kinetics under consideration of the effects from electron cooling and multiple scattering of the beam on a supersonic gas jet target have been carried out as well. The life time, equilibrium momentum spread and equilibrium lateral spread during collisions with this internal gas jet target were estimated. In addition, the results from experiments at the TSR ring, where low intensity beam of CF+ ions at 93 keV/u has been shrunk to extremely small dimensions have been reproduced. Based on these simulations

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

    SciTech Connect

    Wang, G.M.; Shaftan; T.; Cheng; W.X.; Fliller; R.; Heese; R.; Singh; O.; Willeke; F.

    2011-03-28

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

  17. Neutral Beam Ion Loss Modelling for NSTX

    NASA Astrophysics Data System (ADS)

    Darrow, D. S.; Akers, R.; Kaye, S. M.; Mikkelsen, D. R.

    1999-11-01

    The loss of 80 keV D neutral beam ions to the walls has been modeled for a range of plasma conditions in NSTX using the EIGOL code[1]. Initial results of the code are in reasonable agreement with those from the LOCUST code[2]. Both codes predict loss fractions of 20% for a discharge with β_T=40% and q_0=2.6. Losses are strongly concentrated on the front face and edges of the high-harmonic fast wave antenna as it projects farther inward than other internal structures at the midplane. The edges of the passive stabilizer plates near the midplane are also subject to a large flux of lost beam ions under some conditions. The dependence of the loss upon the plasma density profile, I_p, and BT will be presented. [1] D. S. Darrow, et al., in Proceedings of the 26th EPS Conference on Controlled Fusion and Plasma Physics, Maastricht, The Netherlands, 14-18 June 1999. [2] R. Akers, et al., ibid.

  18. A method for generating double-ring-shaped vector beams

    NASA Astrophysics Data System (ADS)

    Huan, Chen; Xiao-Hui, Ling; Zhi-Hong, Chen; Qian-Guang, Li; Hao, Lv; Hua-Qing, Yu; Xu-Nong, Yi

    2016-07-01

    We propose a method for generating double-ring-shaped vector beams. A step phase introduced by a spatial light modulator (SLM) first makes the incident laser beam have a nodal cycle. This phase is dynamic in nature because it depends on the optical length. Then a Pancharatnam–Berry phase (PBP) optical element is used to manipulate the local polarization of the optical field by modulating the geometric phase. The experimental results show that this scheme can effectively create double-ring-shaped vector beams. It provides much greater flexibility to manipulate the phase and polarization by simultaneously modulating the dynamic and the geometric phases. Project supported by the National Natural Science Foundation of China (Grant No. 11547017), the Hubei Engineering University Research Foundation, China (Grant No. z2014001), and the Natural Science Foundation of Hubei Province, China (Grant No. 2014CFB578).

  19. Beam position monitors for the Fermilab recycler ring

    NASA Astrophysics Data System (ADS)

    Barsotti, E.; Lackey, S.; McClure, C.; Meadowcroft, R.

    1998-12-01

    Fermilab's new Recycler Ring will recover and cool "used" antiprotons at the end of a Tevatron store and also accumulate "new" antiprotons from the antiproton source. A wideband rf system based on barrier buckets will result in unbunched beam, grouped in one to three separate partitions throughout the ring. A new beam position monitor system will measure position of any one partition at a time, using low-frequency signals from beam distribution edges. A signal path including an elliptical split-plate detector, radiation-resistant tunnel preamplifiers, and logarithmic amplifiers, will result in a held output voltage nearly proportional to position. The results will be digitized using Industry Pack technology and a Motorola MVME162 processor board. The data acquisition subsystem, including digitization and timing for 80 position channels, will occupy two VME slots. System design will be described, with some additional emphasis on the use of logamp chips.

  20. Transient beam loading compensation in the Fermilab Main Ring

    SciTech Connect

    Wildman, D.

    1985-10-01

    A requirement for bunch coalescing and bunch rotation for antiproton production in the Fermilab Main Ring is that the net rf voltages be reduced below about 1 kV. At high beam intensities, the fields generated by the beam in a single pass through the rf cavities will exceed this limit. The new compensation system monitors the component of the beam current at the fundamental rf frequency as a function of time. This information is then delayed by a single turn and fed back into the high level rf system to cancel the beam-induced fields. The system has compensated the beam-induced voltage generated by a single booster batch to 5% of its initial value.

  1. Beam loss and radiation effects in the SSC lattice elements

    SciTech Connect

    Baishev, I.S.; Drozhdin, A.I.; Mokhov, N.V. |

    1990-11-01

    The Superconducting Super Collider (SSC) is designed to be an advanced machine with relatively low beam loss-induced radiation levels. However, a fraction of the beam lost in the lattice due to pp-collisions at the interaction points, beam-gas scattering, bearn-halo scraping, various instabilities and errors will result in the irradiation of conventional and superconducting components of the accelerator and experimental apparatus. The level of the beam loss and its distribution along the machine structure has impact on all of the three crucial radiation effects at the SSC: quenching of the superconducting magnets, survivability of the accelerator and detectors components in the near-beam regions, and influence to the environment. This paper, based on the full-scale Monte Carlo simulation, will explore all major sources of beam loss in the Collider and measures to reduce the irradiation of the accelerator components. Basic parameters of the Super Collider accepted throughout this report are as follows: Proton energy E{sub 0} = 20 TeV, injection energy is 2 TeV, number of protons circulating in each of the collider rings is N = 1.3 {times} 10{sup 14}, circumference is 87.12 km, the transverse normalized emittance {var_epsilon}{sub N}({sigma}) = 1 {pi} mm-mrad, for the regular lattice ({beta} = 305 m) the beam R.M.S. sizes are {sigma} = 0.12 mm at 20 TEV and {sigma} = 0.38 mm at the injection energy. The dipole length is 15.815 m with the effective field length of 15.165 m. The magnetic field map for B{sub 0} = 6.5999 T has been calculated with the POISSON program by Greg Snitchler. The turn angle of each dipole is {alpha} = 1.50027 mrad. The dipole aperture is 50 mm. The two beam pipe diameters are studied 33 and 40 mm. The operating temperature is T{sub 0} = 4.35 K.

  2. Collimation system design for beam loss localization with slipstacking injection in the Fermilab Main Injector

    SciTech Connect

    Drozhdin, A.I.; Brown, B.C.; Johnson, D.E.; Koba, K.; Kourbanis, I.; Mokhov, N.V.; Rakhno, I.L.; Sidorov, V.I.; /Fermilab

    2007-06-01

    Results of modeling with the 3-D STRUCT and MARS15 codes of beam loss localization and related radiation effects are presented for the slipstacking injection to the Fermilab Main Injector. Simulations of proton beam loss are done using multi-turn tracking with realistic accelerator apertures, nonlinear fields in the accelerator magnets and time function of the RF manipulations to explain the results of beam loss measurements. The collimation system consists of one primary and four secondary collimators. It intercepts a beam power of 1.6 kW at a scraping rate of 5% of 5.5E+13 ppp, with a beam loss rate in the ring outside the collimation region of 1 W/m or less. Based on thorough energy deposition and radiation modeling, a corresponding collimator design was developed that satisfies all the radiation and engineering constraints.

  3. Analysis of beam loss induced abort kicker instability

    SciTech Connect

    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.

  4. BEAM LOSS MITIGATION IN THE OAK RIDGE SPALLATION NEUTRON SOURCE

    SciTech Connect

    Plum, Michael A

    2012-01-01

    The Oak Ridge Spallation Neutron Source (SNS) accelerator complex routinely delivers 1 MW of beam power to the spallation target. Due to this high beam power, understanding and minimizing the beam loss is an ongoing focus area of the accelerator physics program. In some areas of the accelerator facility the equipment parameters corresponding to the minimum loss are very different from the design parameters. In this presentation we will summarize the SNS beam loss measurements, the methods used to minimize the beam loss, and compare the design vs. the loss-minimized equipment parameters.

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

    SciTech Connect

    Wu, Juhao; Raubenheimer, T.O.; Chao, A.W.; Seryi, A.; Sramek, C.K.; /Rice U.

    2005-06-30

    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.

  6. Transverse instability of the antiproton beam in the Recycler Ring

    SciTech Connect

    Prost, L.R.; Bhat, C.M.; Burov, A.; Crisp, J.; Eddy, N.; Hu, M.; Shemyakin, A.; /Fermilab

    2011-03-01

    The brightness of the antiproton beam in Fermilab's 8 GeV Recycler ring is limited by a transverse instability. This instability has occurred during the extraction process to the Tevatron for large stacks of antiprotons even with dampers in operation. This paper describes observed features of the instability, introduces the threshold phase density to characterize the beam stability, and finds the results to be in agreement with a resistive wall instability model. Effective exclusion of the longitudinal tails from Landau damping by decreasing the depth of the RF potential well is observed to lower the threshold density by up to a factor of two.

  7. Beam 'notching' tests with the main ring super damper

    SciTech Connect

    Halling, Mike; Crisp, Jim; /Fermilab

    1995-01-01

    The original operations scenario to provide 12 proton bunches for the accelerator studies in the fall had them injecting 12 partial Booster batches into the main ring, accelerating them to flattop, then coalescing them. One of the main limitations of these coalescing studies for the last few months has been the inability of the Booster to provide enough beam without radiation trips. These radiation trips are considered difficult to eliminate due to the fact that the unwanted Booster beam cannot be aborted cleanly. During last week's study period they successfully used a new method that shows much promise.

  8. Ion bunch length effects on the beam-beam interaction and its compensation in a high-luminosity ring-ring electron-ion collider

    SciTech Connect

    Montag C.; Oeftiger, A.; Fischer, W.

    2012-05-20

    One of the luminosity limits in a ring-ring electron-ion collider is the beam-beam effect on the electrons. In the limit of short ion bunches, simulation studies have shown that this limit can be significantly increased by head-on beam-beam compensation with an electron lens. However, with an ion bunch length comparable to the beta-function at the IP in conjunction with a large beam-beam parameter, the electrons perform a sizeable fraction of a betatron oscillation period inside the long ion bunches. We present recent simulation results on the compensation of this beam-beam interaction with multiple electron lenses.

  9. Absolute beam energy measurements in e+e- storage rings

    NASA Astrophysics Data System (ADS)

    Placidi, M.

    1997-01-01

    The CERN Large Electron Positron collider (LEP) was dedicated to the measurement of the mass Mz and the width Γz of the Z0 resonance during the LEP1 phase which terminated in September 1995. The Storage Ring operated in Energy Scan mode during the 1993 and 1995 physics runs by choosing the beam energy Ebeam to correspond to a center-of-mass (CM) energy at the interaction points (IPs) ECMpeak±1762 MeV. After a short review of the techniques usually adopted to set and control the beam energy, this paper describes in more detail two methods adopted at LEP for precise beam energy determination that are essential to reduce the contribution to the systematic error on Mz and Γz. The positron beam momentum was initially determined at the 20-GeV injection energy by measuring the speed of a less relativistic proton beam circulating on the same orbit, taking advantage of the unique opportunity to inject two beams into the LEP at short time intervals. The positron energy at the Z0 peak was in this case derived by extrapolation. Once transverse polarization became reproducible, the Resonant Depolarization (RD) technique was implemented at the Z0 operating energies, providing a ⩽2×10-5 instantaneous accuracy. RD Beam Energy Calibration has been adopted during the LEP Energy Scan campaigns as well as in Accelerator Physics runs for accurate measurement of machine parameters.

  10. Controlling Fano resonance of ring/crescent-ring plasmonic nanostructure with Bessel beam.

    PubMed

    Xiao, Fajun; Zhu, Weiren; Premaratne, Malin; Zhao, Jianlin

    2014-01-27

    We propose a method to dynamically control the Fano resonance of a ring/crescent-ring gold nanostructure by spatially changing the phase distribution of a probe Bessel beam. We demonstrate that a highly tunable Fano interference between the quadrupole and bright dipole modes can be realized in the near-infrared range. Even though a complex interference between a broad resonance and a narrower resonance lead to these observations, we show that a simple coupled oscillator model can accurately describe the behavior, providing valuable insights into the dynamics of the system. A further analysis of this structure uncovers a series of interesting phenomena such as anticrossing, sign changing of coupling and the spectral inversion of quadrupole and bright dipole modes. We further show that near field enhancement at Fano resonance can be actively controlled by modulating the phase distribution of the exciting incident Bessel beam. PMID:24515223

  11. SUPERCONDUCTING RING CYCLOTRON FOR RIKEN RI BEAM FACTORY IN JAPAN

    SciTech Connect

    Okuno, H.; Dantsuka, T.; Yamada, K.; Kase, M.; Maie, T.; Kamigaito, O.

    2010-04-09

    Since 1997, RIKEN Nishina Center has been constructing the Radioactive Isotope Beam Factory (RIBF) and succeeded in beam commissioning of its accelerator complex at the end of 2006. The world's first superconducting ring cyclotron (SRC) is the final booster in the RIBF accelerator complex which is able to accelerate all-element heavy ions to a speed of about 70% of the velocity of light. The ring cyclotron consists of 6 major superconducting sector magnets with a maximum field of 3.8 T. The total stored energy is 235 MJ, and its overall sizes are 19 m diameter, 8 m height and 8,300 tons. The magnet system assembly was completed in August 2005, and successfully reached the maximum field in November 2005. The first beam was extracted at the end of 2006 and the first uranium beam was extracted in March 2007. However operation of the helium refrigerator was not satisfactory although the commissioning of SRC was successful. Operation was stopped every two month due to degradation of its cooling power. In February 2008 the reason of the degradation was revealed to be oil contamination. Operation of the cryogenic system was restarted from August 2008 after hard task to clean up the helium refrigerator and to add oil separators to the compressor. After restoration long-term steady operation to keep the magnet superconducting continued for about 8 months with no sign of degradation of cooling capacity.

  12. Model for nonlinear evolution of localized ion ring beam in magnetoplasma

    SciTech Connect

    Scales, W. A.; Ganguli, G.; Mithaiwala, M.; Rudakov, L.

    2012-06-15

    An electrostatic hybrid model, which investigates the nonlinear evolution of a localized ion ring beam in a magnetoplasma, is described and applied to the generation and evolution of turbulence in the very low frequency (VLF) ({Omega}{sub ci}<{omega}<{Omega}{sub ce}) range, where {Omega}{sub ci(e)} is the ion (electron) gyro frequency. Electrons are treated as a fluid and the ions with the particle-in-cell method. Although the model is electrostatic, it includes the effects of energy loss by convection of electromagnetic VLF waves out of the instability region by utilizing a phenomenological model for effective collisions with the fluid electrons. In comparison with a more conventional electrostatic hybrid model, the new model shows much more efficient extraction of energy from the ion ring beam and reduced background plasma heating over a range of parameters.

  13. Polarized Ion Beams in Figure-8 Rings of JLab's MEIC

    SciTech Connect

    Derbenev, Yaroslav; Lin, Fanglei; Morozov, Vasiliy; Zhang, Yuhong; Kondratenko, Anatoliy; Kondratenko, M A; Filatov, Yury

    2014-07-01

    The Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab is designed to provide high polarization of both colliding beams. One of the unique features of JLab's MEIC is figure-8 shape of its rings. It allows preservation and control of polarization of all ion species including small-anomalous-magnetic-moment deuterons during their acceleration and storage. The figure-8 design conceptually expands the capability of obtaining polarized high-energy beams in comparison to conventional designs because of its property of having no preferred periodic spin direction. This allows one to control effectively the beam polarization by means of magnetic insertions with small field integrals. We present a complete scheme for preserving the ion polarization during all stages of acceleration and its control in the collider's experimental straights.

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

    SciTech Connect

    Dobbs, Adam James

    2011-10-01

    A study is presented of particle rates in the MICE Muon Beamline and their relationship to beam loss produced in ISIS. A brief overview of neutrino physics is presented, together with a discussion on the Neutrino Factory as a motivation for MICE. An overview of MICE itself is then presented, highlighting the need for a systematic understanding of the relationship between the MICE target parameters, ISIS beam loss, and MICE particle rate. The variation of beam loss with target depth is examined and observed to be non-linear. The variation of beam loss with respect to the target dip time in the ISIS cycle is examined and observed to be approximately linear for dip times between 11.1 ms and 12.6 ms after ISIS injection, before tailing at earlier dip times. The variation of beam loss with particle rate is also observed to follow an approximately linear relationship from 0.05 V.ms to 4.7 V.ms beam loss, with a further strong indication that this continues up to 7.1 V.ms. Particle identification using time-of-flight data is used to give an insight into the relative abundances of each particle species present in the MICE beam. Estimates of muon rate are then produced as a function of beam loss. At a level of 2 V.ms beam loss ~10:9 muons per spill for a 3.2 ms spill with negative π → μ optics, and ~31:1 muons per 1 ms spill with positive π → μ optics are observed. Simulations using the ORBIT particle tracking code of the beam loss distributions around the ISIS ring, caused by the MICE target, are also presented and the implications for MICE running discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

  16. Analysis of beam loss mechanism in the Project X linac

    SciTech Connect

    Carneiro, J.-P.; Lebedev, V.; Nagaitsev, S.; Ostiguy, J.-F.; Solyak, N.; /Fermilab

    2011-03-01

    Minimization of the beam losses in a multi-MW H{sup -} linac such as ProjectX to a level below 1 W/m is a challenging task. The impact of different mechanism of beam stripping, including stripping in electric and magnetic fields, residual gas, blackbody radiation and intra-beam stripping, is analyzed. Other sources of beam losses are misalignements of beamline elements and errors in RF fields and phases. We present in this paper requirements for dynamic errors and correction schemes to keep beam losses under control.

  17. Local beam position feedback experiments on the ESRF storage ring

    SciTech Connect

    Chung, Y.; Kahana, E.; Kirchman, J.

    1995-06-01

    This paper describes the results of local beam position feedback experiments conducted on the ESRF storage ring using digital signal processing (DSP) under the trilateral agreement of collaboration among ESRF, APS, and SPring-8. Two rf beam position monitors (BPMS) in the, upstream and downstream of the insertion device (ID) and two x-ray BPMs in the sixth cell were used to monitor the electron beam and the x-ray beam emitted from the ID, respectively. The local bump coefficients were obtained using the technique of singular value decomposition (SVD) on the global response matrix for the bump magnets and all the available BPMs outside the local bump. The local response matrix was then obtained between the two three-magnet bumps and the position monitors. The data sampling frequency was 4 kHz and a proportional, integral, and derivative (PID) controller was used. The result indicates the closed-loop feedback bandwidth close to 100 Hz and clear attenuation ({approx} {minus}40 dB) of the 7-Hz beam motion due to girder vibration resonance. Comparison of the results using the rf BPMs and x-ray BPMs will be also discussed.

  18. Electron storage ring beam lifetime dependence on pressure and pumping speed

    SciTech Connect

    Halama, H.J.

    1984-01-01

    The beam loss in electron storage rings depends to a large extent on the interaction of the beam with heavier residual gas molecules such as CO, CO/sub 2/ and A due to Bremsstrahlung and Coulomb scattering. The gas density inside the vacuum chamber is determined by the surface condition of the vacuum chamber which is bombarded by photons (synchrotron radiation) generated by circulating electron beams and by the installed pumping. During the spring shutdown the x-ray ring vacuum system was updated and baked out. Residual gas spectra obtained were typical of a well baked out system, i.e., hydrogen constituted approx. 95% of the gas and the average pressure was in the 10/sup -10/ Torr range. During initial operation the composition of desorbed gases was 43% H/sub 2/, 25% CO and 16% CO/sub 2/ and CH/sub 4/. After 3 months of beam conditioning desorption dropped by a factor of 5 and the CO, CO/sub 2/ and CH/sub 4/ peaks represented smaller percentage of total desorbed gas. Beam lifetime did not, however, show a corresponding increase. The pumping speed of distributed pumps dropped to zero at 1 x 10/sup -9/ Torr pressure but increased rapidly from approx. 20l/s in low 10/sup -9/ as the pressure increased.

  19. Characterizing and Controlling Beam Losses at the LANSCE Facility

    SciTech Connect

    Rybarcyk, Lawrence J.

    2012-09-12

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

  20. Impedances and beam stability issues of the Fermilab recycler ring

    SciTech Connect

    Ng, King-Yuen

    1996-04-01

    The Fermilab Recycler Ring (permanent magnets) will be built on top of the Fermilab Main Injector sharing the same tunnel; its main function is to recycle the anti-protons after a store in the Tevatron and to provide storage for them after after accumulation and cooling in the Accumulator. Estimates of coupling impedances show domination by space charge. Examination of longitudinal instabilities shows that microwave instability will not occur if there are only N = 2.53 x 10{sup 12} anti-protons in the beam. Longitudinal coupling-bunch instability during injection stacking does not appear possible because of long bunch lengths/short bunch gaps and lack of sharp resonances. Transverse instability, on the other hand, cannot be Landau damped by the momentum spread in the beam, but it can be cured by a small spread in the betatron tunes (either from space charge or an octupole).

  1. Minimization of first-turn losses by excited neutrals in charge-changing injection of accumulator rings

    SciTech Connect

    Jason, A.J.; Blind, B.; Channel, P.; Wang, Tai-Sen

    1994-07-01

    Substantial beam losses, due to production of excited neutrals by the foil stripper, have been observed to occur immediately after injection in accumulator rings that utilize charge-changing injection. A technique is proposed, based on experimental and theoretical results for excited-state production and stripping, that is potentially capable of reducing such losses by a factor greater than 10{sup 4}. In the technique, foil stripping occurs in a shaped magnetic field that resolves the excited atomic levels into immediately stripped states that are within ring acceptance and those that can be ejected from the ring. An added magnetic-mirror-field configuration is Proposed as an effective means of minimizing interactions between stripped electrons and the foil.

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

    SciTech Connect

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

    2010-02-03

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

  3. Cavity loss factors for non-ultrarelativistic beams

    SciTech Connect

    Kurennoy, S.S.

    1998-12-31

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

  4. BEAM LOSS ESTIMATES AND CONTROL FOR THE BNL NEUTRINO FACILITY.

    SciTech Connect

    WENG, W.-T.; LEE, Y.Y.; RAPARIA, D.; TSOUPAS, N.; BEEBE-WANG, J.; WEI, J.; ZHANG, S.Y.

    2005-05-16

    The requirement for low beam loss is very important both to protect the beam component, and to make the hands-on maintenance possible. In this report, the design considerations to achieving high intensity and low loss will be presented. We start by specifying the beam loss limit at every physical process followed by the proper design and parameters for realizing the required goals. The process considered in this paper include the emittance growth in the linac, the H{sup -} injection, the transition crossing, the coherent instabilities and the extraction losses.

  5. A Flexible, Low Cost, Beam Loss Monitor Evaluation System

    SciTech Connect

    Hoyes, George Garnet; Pimol, Piti; Juthong, Nawin; Attaphibal, Malee

    2007-01-19

    A flexible, low cost, Beam Loss Monitor (BLM) Evaluation System based on Bergoz BLMs has been developed. Monitors can easily be moved to any location for beam loss investigations and/or monitor usefulness evaluations. Different PC pulse counting cards are compared and tested for this application using the display software developed based on LabVIEW. Beam problems uncovered with this system are presented.

  6. Suppression of Beam-Ion Instability in Electron Rings with Multi-Bunch Train Beam Fillings

    SciTech Connect

    Wang, L.; Cai, Y.; Raubenheimer, T.O.; Fukuma, H.; /KEK, Tsukuba

    2011-08-18

    The ion-caused beam instability in the future light sources and electron damping rings can be serious due to the high beam current and ultra-small emittance of picometer level. One simple and effective mitigation of the instability is a multi-bunch train beam filling pattern which can significantly reduce the ion density near the beam, and therefore reduce the instability growth rate up to two orders of magnitude. The suppression is more effective for high intensity beams with low emittance. The distribution and the field of trapped ions are benchmarked to validate the model used in the paper. The wake field of ion-cloud and the beam-ion instability is investigated both analytically and numerically. We derived a simple formula for the build-up of ion-cloud and instability growth rate with the multi-bunch-train filling pattern. The ion instabilities in ILC damping ring, SuperKEKB and SPEAR3 are used to compare with our analyses. The analyses in this paper agree well with simulations.

  7. Beam Loss Studies for the 2-MW LBNE Proton Beam Line

    SciTech Connect

    Drozhdin, A.I.; Childress, S.R.; Mokhov, N.V.; Tropin, I.S.; Zwaska, R.; /Fermilab

    2012-05-01

    Severe limits are put on allowable beam loss during extraction and transport of a 2.3 MW primary proton beam for the Long Baseline Neutrino Experiment (LBNE) at Fermilab. Detailed simulations with the STRUCT and MARS codes have evaluated the impact of beam loss of 1.6 x 10{sup 14} protons per pulse at 120 GeV, ranging from a single pulse full loss to sustained small fractional loss. It is shown that loss of a single beam pulse at 2.3 MW will result in a catastrophic event: beam pipe destruction, damaged magnets and very high levels of residual radiation inside and outside the tunnel. Acceptable beam loss limits have been determined and robust solutions developed to enable efficient proton beam operation under these constraints.

  8. Conceptual design of elliptical cavities for intensity and position sensitive beam measurements in storage rings

    NASA Astrophysics Data System (ADS)

    Sanjari, M. S.; Chen, X.; Hülsmann, P.; Litvinov, Yu A.; Nolden, F.; Piotrowski, J.; Steck, M.; Stöhlker, Th

    2015-11-01

    Position sensitive beam monitors are indispensable for the beam diagnostics in storage rings. Apart from their applications in the measurements of beam parameters, they can be used in non-destructive in-ring decay studies of radioactive ion beams as well as enhancing precision in the isochronous mass measurement technique. In this work, we introduce a novel approach based on cavities with elliptical cross-section, in order to compensate the limitations of known designs for the application in ion storage rings. The design is aimed primarily for future heavy ion storage rings of the FAIR project. The conceptual design is discussed together with simulation results.

  9. Black rings with fourth dipole cause less hair loss

    NASA Astrophysics Data System (ADS)

    Chowdhury, Borun D.

    2012-07-01

    An example of entropy enigma with a controlled CFT dual was recently studied in [1]. The enigmatic bulk configurations, considered within the STU model, can be mapped under spectral flow into black rings with three monopole and dipole charges. Even though the bulk and CFT configurations existed in the same region of parameter space, the Bekenstein-Hawking entropy of the bulk configurations was found to be lower than the microscopic entropy from the CFT. While it is possible that the difference in entropy is due to the bulk and boundary configurations being at different points in the moduli space, it is also possible that the bulk configurations embeddable within the STU model are not the most entropic. New families of BPS black ring solutions with four electric and four dipole magnetic charges have recently been explicitly constructed in [2]. These black rings are not embeddable within the STU model. In this paper we investigate if these black rings can be entropically dominant over the STU model black rings. We find that the new black rings are always entropically subdominant to the STU-model black rings. However, for small fourth dipole charge these black rings continue to be dominant over the BMPV in a small region of parameters and are thus enigmatic.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  11. Observations And Measurements of Anomalous Hollow Electron Beams in a Storage Ring

    SciTech Connect

    Wu, Y.K.; Li, J.; Wu, J.; /SLAC

    2006-02-06

    Anomalous hollow electron beams have been recently observed in the Duke storage ring. With a single bunch beam in a lattice with a negative chromaticity, a hollow beam can be created. This beam consists of a solid core beam inside and a large ring beam outside. In this paper, we report the measurements of the hollow beam phenomenon, including its distinct image pattern and spectrum signature, and its evolution with time. By capturing the post-instability bursting beam, the hollow beam is a unique model system for studying transverse instabilities, in particular, the interplay of the wakefield and lattice nonlinearity. The hollow beam can also be used as a tool to study linear and nonlinear particle dynamics in the storage ring.

  12. H- AND PROTON BEAM LOSS COMPARISON AT SNS SUPERCONDUCTING LINAC

    SciTech Connect

    Aleksandrov, Alexander V; Galambos, John D; Plum, Michael A; Shishlo, Andrei P

    2012-01-01

    A comparison of beam loss in the superconducting part (SCL) of the Spallation Neutron Source (SNS) linac for H- and protons is presented. During the experiment the nominal beam of negative hydrogen ions in the SCL was replaced by a proton beam created by insertion of a thin stripping carbon foil placed in the low energy section of the linac. The observed significant reduction in the beam loss for protons is explained by a domination of the intra beam stripping mechanism of the beam loss for H-. The details of the experiment are discussed, and a preliminary estimation of the cross section of the reaction H- + H- -> H- + H0 + e is presented. Earlier, a short description of these studies was presented in [1].

  13. BEAM INDUCED ENERGY DEPOSITION IN MUON STORAGE RINGS.

    SciTech Connect

    MOKHOV,N.V.; JOHNSTONE,C.J.; PARKER,B.L.

    2001-06-18

    Beam-induced radiation effects have been simulated for 20 and 50 GeV muon storage rings designed for a Neutrino Factory. It is shown that by appropriately shielding the superconducting magnets, quench stability, acceptable dynamic heat loads, and low residual dose rates can be achieved. Alternatively, if a specially-designed skew focusing magnet without superconducting coils on the magnet's mid-plane is used, then the energy is deposited preferentially in the warm iron yoke or outer cryostat layers and internal shielding may not be required. In addition to the component irradiation analysis, shielding studies have been performed. Calculations of the external radiation were done for both designs but the internal energy deposition calculations for the 20 GeV Study-2 lattice are still in progress.

  14. Beam-induced energy deposition in muon storage rings

    SciTech Connect

    Nikolai V. Mokhov; Carol J. Johnstone; Brett Parker

    2001-06-22

    Beam-induced radiation effects have been simulated for 20 and 50 GeV muon storage rings designed for a Neutrino Factory. It is shown that by appropriately shielding the superconducting magnets, quench stability, acceptable dynamic heat loads, and low residual dose rates can be achieved. Alternatively, if a specially-designed skew focusing magnet without superconducting coils on the magnet's mid-plane is used, then the energy is deposited preferentially in the warm iron yoke or outer cryostat layers and internal shielding may not be required. In addition to the component irradiation analysis, shielding studies have been performed. Calculations of the external radiation were done for both designs but the internal energy deposition calculations for the 20 GeV Study-2 lattice are still in progress.

  15. Beam-based modeling and control of storage rings

    NASA Astrophysics Data System (ADS)

    Safranek, J.

    1997-05-01

    Analysis of the measured orbit response matrix is a powerful technique for debugging the linear optics of storage rings. The orbit response matrix is the change in orbit at the beam position monitors (BPMs) with changes in steering magnet excitation. Results will be presented from a computer code called LOCO (Linear Optics from Closed Orbits) that has been used to analyze the response matrices from several synchrotron light sources including the ALS, APS, NSLS VUV, NSLS X-Ray, and SRRC storage rings. The analysis accurately determines the individual quadrupole magnet gradients as well as the gains of BPMs and the calibrations of the steering magnets. The coupling terms of the response matrix such as the shift in vertical orbit from horizontal steering magnets can be included in the analysis to give the role of the quadrupoles, BPMs and steering magnets. The LOCO code can also be used to find the changes in quadrupole gradient that best compensate for gradient errors from insertion devices and sextupoles. In this way the design periodicity of the linear optics can be restored.

  16. Stable ring beam of solar wind He2+ in the magnetosheath

    NASA Astrophysics Data System (ADS)

    Tsubouchi, K.; Nagai, T.; Shinohara, I.

    2016-02-01

    Heavier, or large mass-per-charge, ion species like helium ions (He2+) in the solar wind are decelerated less than protons at the Earth's bow shock. The resulting velocity difference in the magnetosheath forms a ring beam around the core protons. In this study, we identified the presence of such a ring beam composed of He2+ ions in the magnetosheath from observations from the Geotail spacecraft. Previous studies have shown that the ring distribution induces ion cyclotron waves that rapidly scatter the He2+ ring beam, leading to evolution into a shell or to a Maxwellian distribution. In contrast, the present event suggested that the He2+ ring beam persisted for the order of 10 min, i.e., hundreds of ion gyroperiods. One-dimensional hybrid simulations of a quasi-perpendicular, low Mach number shock (θ = 85°,MA ˜ 2.5) showed that the lower density of He2+ ions (less than 1% to protons) is the crucial condition that accounts for the long-duration property of the ring beam. Weaker wave activity was insufficient to scatter He2+ ions, whereas two-dimensional simulations showed a rapid scattering of the ring beam as suggested in the previous studies. Comparison between these results indicated that there are still controversial issues concerning the dynamics of minor ions in the magnetosheath, whether the He2+ ring beam is really stable, and what parameters control the stability condition.

  17. Electron beam stability and beam peak to peak motion data for NSLS X-Ray storage ring

    SciTech Connect

    Singh, O.

    1993-07-01

    In the past two years, a significant reduction in electron beam motion has been achieved at the NSLS X-Ray storage ring. The implementation of global analog orbit feedbacks, based on a harmonics correction scheme, has reduced the beam motion globally. Implementation of six local analog feedback systems has reduced the beam motion even further at the corresponding beam line straight sections. This paper presents beam motion measurements, showing the improvement due to the feedback systems. Beam motion is measured using a spectrum analyzer and data is presented at various frequencies, where peaks were observed. Finally, some of the beam motion sources are discussed.

  18. Ring formation in self-focusing of electromagnetic beams in plasmas

    SciTech Connect

    Faisal, M.; Mishra, S. K.; Verma, M. P.; Sodha, M. S.

    2007-10-15

    This article presents a paraxial theory of ring formation as an initially Gaussian beam propagates in a nonlinear plasma, characterized by significant collisional or ponderomotive nonlinearity. Regions in the axial irradiance-(beam width){sup -2} space, for which the ring formation occurs and the paraxial theory is valid, have been characterized; for typical points in these regions the dependence of the beam width parameter and the radial distribution of irradiance on the distance has been specifically investigated and discussed.

  19. Influence of emitter ring manufacturing tolerances on electron beam quality of high power gyrotrons

    NASA Astrophysics Data System (ADS)

    Pagonakis, Ioannis Gr.; Illy, Stefan; Thumm, Manfred

    2016-08-01

    A sensitivity analysis of manufacturing imperfections and possible misalignments of the emitter ring in the gyrotron cathode structure on the electron beam quality has been performed. It has been shown that a possible radial displacement of the emitter ring of the order of few tens of microns can cause dramatic effects on the beam quality and therefore the gyrotron operation. Two different design approaches are proposed in order to achieve an electron beam which is less sensitive to manufacturing imperfections.

  20. FEL indulators with the hollow-ring electron beam

    SciTech Connect

    Epp, V.; Bordovitsyn, V.; Kozhevnikov, A.

    1995-12-31

    A conceptual design of undulators with a modulated longitudinal magnetic field is proposed. The magnetic field is created by use of a solenoid with axis coincident with the electron beam axis. In order to modulate the magnetic field we propose an insertion of a row of alternating ferromagnetic and superconducting diaphragms in line with electron beam. The simulation of two-dimensional distribution of the magnetic field in the plane containing undulator axis was made using the computer code {open_quotes}Mermaid{close_quotes}. The magnetic field was analysed as a function of the system geometry. The dependence on the spacing l between superconducting diaphragms, inner a and outer b radii of the last ones is investigated. Two versions of the device are considered: with ferromagnetic rings made of magnetically soft material placed between the superconducting diaphragms and without them. It is shown that the field modulation depth increases with ratio of b/l and can exceed 50% in case of the ferromagnetic insertions. An approximate analytical calculation of the magnetic field distribution is performed as follows. The axial-symmetrical magnetic field can be defined by the vector potential with only one nonzero component A(r,{phi}) where r and {phi} are the cylindrical coordinates. The solution of the Laplace`s equation is found under the assumption that the magnetic field is infinitely extended and periodic along the z-axis. The boundary conditions are defined by the undulator design. The result is used for the calculation of the particle dynamics and for the investigations of the trajectory stability. The spectral and angular distribution of the radiation emitted from the described systems is found. The estimations show that the proposed design allows to create relatively high magnitude of the magnetic field (up to 1 T) with a short period about 1 cm or less.

  1. Fast PIN-diode beam loss monitors at Tevatron

    SciTech Connect

    Shiltsev, V.

    1997-07-01

    The article is devoted to results of fine time structure of particle losses in Tevatron with use of fast beam loss monitors (BLM) based on PIN-diodes. An ultimate goal of the new BLMs is to distinguish losses of protons and antiprotons from neighbor bunches with 132 ns bunch spacing in the Tevatron collider upgrade. The devices studied fit well to the goal as they can recognize even seven times closer - 18.9 ns - spaced bunches` losses in the Tevatron fixed target operation regime. We have measured main characteristics of the BLM as well as studied the proton losses over 10 decades of time scale - from dozen of minutes to dozen of nanoseconds. Power spectral density of the losses is compared with spectra of the proton beam motion.

  2. MHD Induced Neutral Beam Ion Loss from NSTX Plasmas

    SciTech Connect

    D.S. Darrow, E.D. Fredrickson, N.N. Gorelenkov, A.L. Roquemore, and K. Shinohara

    2007-12-13

    Bursts of ~60 kHz activity on Mirnov coils occur frequently in NSTX plasmas and these are accompanied by bursts of neutral beam ion loss over a range in pitch angles. These losses have been measured with a scintillator type loss probe imaged with a high speed (>10,000 frames/s) video camera, giving the evolution of the energy and pitch angle distributions of the lost neutral beam ions over the course of the events. The instability occurs below the TAE frequency in NSTX (~100 kHz) in high beta plasmas and may be a beta driven Alfvén acoustic (BAAE) mode.

  3. Individual Beam Size And Length Measurements at the SLC Interaction Point Derived From the Beam Energy Loss During a Beam Beam Deflection Scan

    SciTech Connect

    Raimondi, P.; Field, R.Clive; Phinney, N.; Ross, M.C.; Slaton, T.; Traller, R.; /SLAC

    2011-08-26

    At the Interaction Point (IP) of the SLC Final Focus, beam-beam deflection scans routinely provide a measurement of the sum in quadrature of the electron and positron transverse beam sizes, but no information on the individual beam sizes. During the 1996 SLC run, an upgrade to the Final Focus beam position monitor system allowed a first measurement of the absolute beam energy loss of both beams on each step of the deflection scan. A fit to the energy loss distributions of the two beams provides a measurement not only of the individual transverse beam sizes at the IP but also of the individual bunch lengths.

  4. Ring dislocation of a coherence of vortex Bessel beams in turbulent atmosphere

    NASA Astrophysics Data System (ADS)

    Lukin, Igor P.

    2014-11-01

    Researches of coherent properties of the vortex Bessel optical beams propagating in turbulent atmosphere are theoretically developed. The degree of coherence of vortex Bessel optical beams depending on beam parameters (crosssection wave number and a topological charge) and characteristics of turbulent atmosphere is in details analysed. It is shown, that at low levels of fluctuations in turbulent atmosphere, the degree of coherence of a vortex Bessel optical beam essentially depends on value of a topological charge of a beam. In the central part of a two-dimensional field of degree of coherence the ring dislocations, which number of rings to equally value of a topological charge of a vortex optical beam, is formed. At high levels of fluctuations in turbulent atmosphere, the degree of coherence of a vortex Bessel beam decreases much faster, than it takes place for the fundamental Bessel beam. And, speed of decrease essentially increases in process of growth of value of a topological charge of a beam.

  5. Formation of a ring dislocation of a coherence of a vortex optical beam in turbulent atmosphere

    NASA Astrophysics Data System (ADS)

    Lukin, Igor P.

    2013-12-01

    Researches of coherent properties of the vortex Bessel optical beams propagating in turbulent atmosphere are theoretically developed. The degree of coherence of vortex Bessel optical beams depending on beam parameters (crosssection wave number and a topological charge) and characteristics of turbulent atmosphere is in details analysed. It is shown, that at low levels of fluctuations in turbulent atmosphere, the degree of coherence of an vortex Bessel optical beam essentially depends on value of a topological charge of a beam. In the central part of a two-dimensional field of degree of coherence the ring dislocations, which number of rings to equally value of a topological charge of a vortex optical beam, is formed. At high levels of fluctuations in turbulent atmosphere, the degree of coherence of a vortex Bessel beam decreases much faster, than it takes place for the fundamental Bessel beam. And, speed of decrease essentially increases in process of growth of value of a topological charge of a beam.

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

    SciTech Connect

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

    2008-03-26

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

  7. Transverse beam feedback system for PLS storage ring

    NASA Astrophysics Data System (ADS)

    Huang, J. Y.; Park, M. K.; Kim, D. T.; Kang, H. S.; Hwang, W. H.; Nam, S. H.

    2001-07-01

    As the stored beam current increases over 240 mA, transverse coupled-beam instability limits higher beam current in Pohang Light Source. A bunch by bunch transverse feedback system has been developed to cure these beam instabilities. It consists of beam oscillation detectors, betatron phase adjuster, power amplifiers and a stripline kicker. Design of each circuit and its functions are described with simple trigonometric equations. The result of the beam test has shown more than 30 dB damping of the beam oscillation in the full bandwidth of the system.

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

    SciTech Connect

    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.

  9. RHIC Beam Loss Monitor System Design and Test

    NASA Astrophysics Data System (ADS)

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

    1997-05-01

    The Beam Loss Monitor 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. To satisfy fast (single turn) and slow (100 msec) loss beam abort criteria and provide sensitivity for studies measurements, a range of over 8 decades is needed. The system uses 400 ion chambers of a modified Tevatron design. An RC pre-integrator reduces the dynamic range for a low current amplifier. This is digitized by a standard RHIC VME MADC preceded by a switchable gain amplifier. The output also goes to an analog multiplier used to reduce energy dependence, extending the range of the abort comparators. Fast and slow filters separate the signal to dual comparators with independent trip levels. The gains, fast and slow abort levels, and abort bit masks are set for each channel on receipt of specific RHIC Event Codes. Up to 64 channels, on 8 VME boards, are controlled by a BNL designed micro-controller based VME module, decoupling it from the front-end computer for real-time operation.

  10. Effects of vertical aperture on beam lifetime at the Advanced Photon Source (APS) storage ring

    SciTech Connect

    Bizek, H.M.

    1995-06-01

    When a positron`s energy deviation {delta}E/E exceeds the rf acceptance, or when it receives an angular kick for the betatron motion that exceeds some limiting admittance, the positron will be lost. The main contributions to the total beam lifetime come from single Coulomb and Touschek scattering. In this report we investigate the dependence of the residual gas pressure and the vertical aperture of the Advanced Photon Source storage ring on the total beam. lifetime. We present results of calculating the total beam lifetime as a function of vertical aperture for varying average ring pressure, beam current, and coupling coefficient.

  11. Numerical analysis on seismic behavior of reinforced concrete beam to concrete filled steel tubular column connections with ring-beam

    NASA Astrophysics Data System (ADS)

    Zhao, Yi.; Xu, Li. Hua.

    2016-06-01

    This paper presents numerical study of the seismic behavior of reinforced concrete beam to concrete filled steel tube column connections with ring-beam. The material stress-strain relations, element type and boundary condition are selected, which are consistent with actual situation. Then the seismic behavior of this type of joint are researched by ABAQUS, and finite element analyses are conducted under cyclic loading. Its parameters are discussed including thickness of steel tubular column wall, sectional dimension of the ring-beam and strength of the core concrete. The results show that the ultimate capacity of the connections is improved with sectional dimension of the ring-beam increased. In the meanwhile, the influence on skeleton curve of the joints is slight of which included thickness of steel tubular column wall and strength of the core concrete.

  12. Theories of statistical equilibrium in electron-positron colliding-beam storage rings

    SciTech Connect

    Schonfeld, J.F.

    1985-01-01

    In this lecture I introduce you to some recent theoretical work that represents a significant and long overdue departure from the mainstream of ideas on the physics of colliding- beam storage rings. The goal of the work in question is to understand analytically - without recourse to computer simulation - the role that dissipation and noise play in the observed colliding-beam behavior of electron-positron storage rings.

  13. On focusing of a ring ripple on a Gaussian electromagnetic beam in a plasma

    SciTech Connect

    Misra, Shikha; Mishra, S. K.

    2008-09-15

    In this communication the authors have investigated the focusing of a ring ripple on a Gaussian electromagnetic beam propagating in a plasma, considering each of the three kinds of basic nonlinearities, namely, ponderomotive, collisional, and relativistic. In this analysis, the electric field profile of the propagating beam is assumed to be composed of the radial electric field distribution of the Gaussian beam as well as that of the ring ripple; a paraxial like approach has been adopted to analyze the characteristics of the propagation. Thus, one considers a unique dielectric function for the beam propagation and a radial field sensitive diffraction term, appropriate to the vicinity of the maximum of the irradiance distribution of the ring ripple. Further, the variation of the phase associated with the beam on account of the r independent terms in the eikonal has also been accounted for.

  14. Beam Control and Steering in the University of Maryland Electron Ring (UMER)

    NASA Astrophysics Data System (ADS)

    Walter, M.; Bai, G.; Bernal, S.; Feldman, D.; Godlove, T.; Haber, I.; Holloway, M.; Kishek, R.; O'Shea, P.; Papadopoulos, C.; Quinn, B.; Reiser, M.; Stratakis, D.; Sutter, D.; Thangaraj, J.; Wilson, M.; Wu, C.

    2006-11-01

    The University of Maryland Electron Ring (UMER) is a low energy, high current recirculator for beam physics research. Ring construction has been completed for multi-turn operation of beams over a broad range of intensities and initial conditions. The electron beam current is adjustable up to 100 mA and pulse length as long as 100 ns. UMER is addressing issues in beam physics relevant to many applications that require intense beams of high quality, such as advanced concept accelerators, free electron lasers, spallalion neutron sources, and future heavy-ion drivers for inertial fusion. The primary focus of this presentation is experimental results in the area of beam steering and control within the injection line and ring. Unique beam steering algorithms now include measurement of the beam response matrix at each quadrupole and matrix inversion by singular value decomposition (SVD). With these advanced steering methods, transport of an intense beam over 50 turns (3600 full lattice periods) of the ring has been achieved.

  15. Simulation Studies of Beam-Beam Effects of a Ring-Ring Electron-Ion Collider Based on CEBAF

    SciTech Connect

    Yuhong Zhang,Ji Qiang

    2009-05-01

    The collective beam-beam effect can potentially cause a rapid growth of beam sizes and reduce the luminosity of a collider to an unacceptably low level. The ELIC, a proposed ultra high luminosity electron-ion collider based on CEBAF, employs high repetition rate crab crossing colliding beams with very small bunch transverse sizes and very short bunch lengths, and collides them at up to 4 interaction points with strong final focusing. All of these features can make the beam-beam effect challenging. In this paper, we present simulation studies of the beam-beam effect in ELIC using a self-consistent strong-strong beam-beam simulation code developed at Lawrence Berkeley National Laboratory. This simulation study is used for validating the ELIC design and for searching for an optimal parameter set.

  16. Reducing support loss in micromechanical ring resonators using phononic band-gap structures

    NASA Astrophysics Data System (ADS)

    Hsu, Feng-Chia; Hsu, Jin-Chen; Huang, Tsun-Che; Wang, Chin-Hung; Chang, Pin

    2011-09-01

    In micromechanical resonators, energy loss via supports into the substrates may lead to a low quality factor. To eliminate the support loss, in this paper a phononic band-gap structure is employed. We demonstrate a design of phononic-crystal (PC) strips used to support extensional wine-glass mode ring resonators to increase the quality factor. The PC strips are introduced to stop elastic-wave propagation by the band-gap and deaf-band effects. Analyses of resonant characteristics of the ring resonators and the dispersion relations, eigenmodes, and transmission properties of the PC strips are presented. With the proposed resonator architecture, the finite-element simulations show that the leaky power is effectively reduced and the stored energy inside the resonators is enhanced simultaneously as the operating frequencies of the resonators are within the band gap or deaf bands. Realization of a high quality factor micromechanical ring resonator with minimized support loss is expected.

  17. Evolution of the ring Airy Gaussian beams with a spiral phase in the Kerr medium

    NASA Astrophysics Data System (ADS)

    Chen, Bo; Chen, Chidao; Peng, Xi; Peng, Yulian; Zhou, Meiling; Deng, Dongmei; Guo, Hong

    2016-05-01

    Nonlinear optical phenomena are of great practical interest in optics. The evolution of ring Airy Gaussian beams with a spiral phase in the nonlinear Kerr medium is investigated using the nonlinear Schrödinger equation. Numerical simulations indicate that the distribution factor b can influence the formation of the ring Airy Gaussian beams. Results show that the beams can be oscillating, and the light filament can be achieved under appropriate laser input power. On the other hand, the evolution of the ring Airy Gaussian beams with a spiral phase in the nonlinear Kerr medium can be implemented, and the numerical simulations of the holographic generation of the ring Airy Gaussian vortex beams propagated in the medium demonstrate that the vortex can be preserved along the propagation. The Poynting vector shows that the energy flow of the ring Airy Gaussian beams flows in the opposite direction on both sides of the focus plane; however, for beams with a spiral phase, the flow direction remains the same; the energy flow can rotate in opposite directions on both sides of the focal plane.

  18. New Beam Loss Monitor for 12 GeV Upgrade

    SciTech Connect

    Jianxun Yan, Kelly Mahoney

    2009-10-01

    This paper describes a new VME based machine protection Beam Loss Monitor (BLM) signal processing board designed at Jefferson Lab to replace the current CAMAC based BLM board. The new eight-channel BLM signal processor has linear, logarithmic, and integrating amplifiers that simultaneously provide the optimal signal processing for each application. Amplified signals are digitized and then further processed through a Field Programmable Gate Array (FPGA). Combining both the diagnostic and machine protection functions in each channel allows the operator to tune-up and monitor beam operations while the machine protection is integrating the same signal. Other features include extensive built-in-self-test, fast shutdown interface (FSD), and 16-Mbit buffers for beam loss transient play-back. The new VME BLM board features high sensitivity, high resolution, and low cost per channel.

  19. beam loss scenarios for MuCool Test Area

    SciTech Connect

    Rakhno, Igor; Johnstone, Carol; /Fermilab

    2010-08-01

    The MuCool Test Area (MTA) is an intense primary beam facility derived directly from the Fermilab Linac to test heat deposition and other technical concerns associated with the liquid hydrogen targets, gas-filled RF cavities, and other apparatus being developed to cool intense, large-emittance muon beams. In this study the results of Monte Carlo modeling of several beam loss scenarios are presented. The MTA facility was designed to test targets and other muon cooling apparatus using the intense Fermilab Linac beam. The requested intensity of the proton beam for the MTA is essentially full Linac capability, or 1.6 x 10{sup 13} protons per pulse and an energy of 400 MeV. Two modes of operation will be supported in the MuCOOL beamline: one mode for emittance measurements (and beamline studies) and a second mode for MTA experiments. Maximum beam intensity for these two modes is: 9.6 x 10{sup 15} protons/hr - 600 beam pulses/hour of full Linac beam pulse intensity (1.6 x 10{sup 13} protons/pulse) to the emittance beam absorber and 9.6 x 10{sup 14} protons/hour - 60 beam pulses/hour of full Linac beam pulse intensity to experiments in the MTA experimental hall. This extremely high intensity implies careful investigation into and application of proper shielding materials and configuration in order to satisfy the following two requirements: (i) to reduce the instantaneous dose rate outside of the experimental enclosure to prescribed levels appropriate for the area considered; (ii) to ensure the civil construction of the hall is capable of additional shielding and, further, that the weight of the shielding is commensurate with the loading specifications of the enclosure, notably the ceiling. A number of scenarios for beam loss at different locations were studied in order to determine the maximum beam intensity which is in compliance with the existing shielding. The modeling was performed with the MARS15 code.

  20. Beam dynamics in a storage ring for neutral (polar) molecules

    SciTech Connect

    Lambertson, Glen R.

    2003-05-01

    The force from a non-uniform electric field on the electric dipole moment of a molecule may be used to circulate and focus molecules in a storage ring. The nature of the forces from multipole electrodes for bending and focusing are described for strong-field-seeking and for weak-field-seeking molecules. Fringe-field forces are analyzed. Examples of storage ring designs are presented; these include long straight sections and provide bunching and acceleration.

  1. DESIREE - A Double Electrostatic Storage Ring for Merged-Beam Experiments

    SciTech Connect

    Danared, H.; Liljeby, L.; Andler, G.; Bagge, L.; Blom, M.; Kaellberg, A.; Leontein, S.; Loefgren, P.; Paal, A.; Rensfelt, K.-G.; Simonsson, A.; Schmidt, H. T.; Cederquist, H.; Larsson, M.; Rosen, S.; Schmidt, K.

    2006-03-20

    DESIREE is a double electrostatic storage ring cooled to cryogenic temperatures. It is built at the Manne Siegbahn Laboratory for merged-beam and single-beam experiments in atomic and molecular physics as well as biophysics. This paper describes the present status of the design of DESIREE.

  2. Beam life time studies and design optimization of the Ultra-low energy Storage Ring

    NASA Astrophysics Data System (ADS)

    Welsch, C. P.; Papash, A. I.; Harasimowicz, J.; Karamyshev, O.; Karamysheva, G. A.; Newton, D.; Panniello, M.; Putignano, M.; Siggel-King, M. R. F.; Smirnov, A.

    2014-04-01

    The Ultra-low energy electrostatic Storage Ring (USR) at the future Facility for Low-energy Antiproton and Ion Research (FLAIR) will provide cooled beams of antiprotons in the energy range between 300 keV down to 20 keV. Based on the original design concept developed in 2005, the USR has been completely redesigned over the past few years by the QUASAR Group. The ring structure is now based on a 'split achromat' lattice. This ensures compact ring dimensions of 10 m × 10 m, whilst allowing both, in-ring experiments with gas jet targets and studies with extracted beams. In the USR, a wide range of beam parameters shall be provided, ranging from very short pulses in the nanosecond regime to a coasting beam. In addition, a combined fast and slow extraction scheme will be featured that allows for providing external experiments with cooled beams of different time structure. Detailed investigations into the dynamics of low energy beams, including studies into the long term beam dynamics and ion kinetics, beam life time, equilibrium momentum spread and equilibrium lateral spread during collisions with an internal target were carried out. This required the development of new simulation tools to further the understanding of beam storage with electrostatic fields. In addition, studies into beam diagnostics methods for the monitoring of ultra-low energy ions at beam intensities less than 10 6 were carried out. This includes instrumentation for the early commissioning of the machine, as well as for later operation with antiprotons. In this paper, on overview of the technical design of the USR is given with emphasis on two of the most important operating modes, long term beam dynamics and the design of the beam diagnostics system.

  3. The Roles of Charge Exchange and Flow-Out Losses in Ring Current Decay

    NASA Astrophysics Data System (ADS)

    Kozyra, J. U.; Liemohn, M. W.

    2001-12-01

    It is becoming clear that flow-out losses are an important ring current decay mechanism in addition to charge-exchange losses. Flow out losses result from an imbalance between the energy flux entering the inner magnetosphere from the nightside plasma sheet and that leaving through the dayside magnetopause before the ring current becomes trapped on closed drift paths. The Michigan ring current drift-loss model (RAM) which calculates ring current losses due to Coulomb drag, charge-exchange and flow-out using realistic geocoronal and dynamical plasmasphere models, has been used to model 8 magnetic storms ranging from moderate to superstorm status. In each case, plasma sheet ion distributions measured by the LANL geosynchronous satellites are used to specify the ring current source population and its dynamical variation. The McIlwain (1986) model is used to specify the inner magnetosphere electric potential pattern which is scaled by the observed polar cap potential values (derived from DMSP passes directly or from the AMIE model) and shielded based on the DMSP auroral boundary index (MBI). Model results indicate that flow-out losses can be driven by an abrupt decrease in plasma sheet density, change in plasma sheet temperature and/or weakening of magnetotail convection prior to northward turning of the IMF. When the IMF abruptly turns northward at the end of the main phase, the entire recovery phase can result from charge-exchange loss. Examples of each of these types of decay are given. RAM decay time scales for all modeled storms are plotted against the simultaneous value of solar wind Ey and compared to the results of statistical studies of this relationship in the literature.

  4. Small size probe for inner profile measurement of pipes using optical fiber ring beam device

    NASA Astrophysics Data System (ADS)

    Wakayama, Toshitaka; Machi, Kizuku; Yoshizawa, Toru

    2012-11-01

    The requirements of inner profile measurement of pipes and holes become recently larger and larger, and applications of inner profile measurement have rapidly expanded to medical field as well as industrial fields such as mechanical, automobile and heavy industries. We have proposed measurement method by incorporating a ring beam device that produces a disk beam and have developed various probes for different inner profile measurement. To meet request for applying to smaller diameter pipes, we tried to improve the ring beam light source using a conical mirror, optical fiber collimator and a laser diode. At this moment a probe with the size of 5 mm in diameter has been realized.

  5. Beam Loss and Longitudinal Emittance Growth in SIS

    SciTech Connect

    Kirk, M.; Hofmann, I.; Boine-Frankenheim, O.; Spiller, P.; Huelsmann, P.; Franchetti, G.; Damerau, H.; Koenig, H. Guenter; Klingbeil, H.; Kumm, M.; Moritz, P.; Schuett, P.; Redelbach, A.

    2005-06-08

    Beam losses of several percent occur regularly in SIS. The onset occurs during the RF capture of the beam. Previous studies have revealed that the losses can come from the RF bucket at the start of acceleration being over filled due to the longitudinal bucket acceptance being too small, or due to the mismatch between the mean energy from the UNILAC and synchronous energy of the SIS. The beam losses as measured by a DC beam transformer however show in addition to the sharp initial drop, for the above reasons, a much slower decay in the beam intensity. The speculated cause comes from the incoherent transverse tune shift of the bunched beam, which forces particles into transverse resonant conditions. The longitudinal emittance growth is also another important issue for SIS. Past measurements from Schottky-noise pick-ups have shown a factor of 3-5 increase in the longitudinal emittance depending on the extraction energy; a large factor when compared against expectations from theory. These factors were calculated from the ratio between the normalized relative momentum spread of the DC beam before RF capture and after debunching. In this present work, tomographical techniques have been used to reconstruct the phasespace from a series of bunch profile measurements from a Beam Position Monitor (BPM). Therefore one can find the rate of growth in the longitudinal emittance from a series of high resolution BPM measurements along the RF ramp. Furthermore the initial phasespace density matrix from these reconstructions has been used to generate the initial population of macroparticles for the ESME longitudinal dynamics Particle-In-Cell code, thereby enabling a comparison between the longitudinal emittance growth of the beam under ideal conditions and that of the experiment. The longitudinal emittance growth (rms) during the acceleration ({approx}540ms) was approximately 20%, and that during the RF capture was estimated to have an upper limit of about 40%. Later measurements

  6. RFQ Designs and Beam-Loss Distributions for IFMIF

    SciTech Connect

    Jameson, Robert A

    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

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

    SciTech Connect

    Bane, Karl; /SLAC

    2012-03-28

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  9. Laser-beam zooming to mitigate crossed-beam energy losses in direct-drive implosions.

    PubMed

    Igumenshchev, I V; Froula, D H; Edgell, D H; Goncharov, V N; Kessler, T J; Marshall, F J; McCrory, R L; McKenty, P W; Meyerhofer, D D; Michel, D T; Sangster, T C; Seka, W; Skupsky, S

    2013-04-01

    Spherically symmetric direct-drive-ignition designs driven by laser beams with a focal-spot size nearly equal to the target diameter suffer from energy losses due to crossed-beam energy transfer (CBET). Significant reduction of CBET and improvements in implosion hydrodynamic efficiency can be achieved by reducing the beam diameter. Narrow beams increase low-mode perturbations of the targets because of decreased illumination uniformity that degrades implosion performance. Initiating an implosion with nominal beams (equal in size to the target diameter) and reducing the beam diameter by ∼ 30%-40% after developing a sufficiently thick target corona, which smooths the perturbations, mitigate CBET while maintaining low-mode target uniformity in ignition designs with a fusion gain ≫ 1. PMID:25166997

  10. Spontaneous and sequential transitions of a Gaussian beam into diffraction rings, single ring and circular array of filaments in a photopolymer.

    PubMed

    Villafranca, Ana B; Saravanamuttu, Kalaichelvi

    2011-08-01

    A Gaussian beam propagating in a photopolymer undergoes self-phase modulation to form diffraction rings and then transforms into a single ring, which in turn ruptures into a necklace of stable self-trapped multimode filaments. The transitions of the beam between the three distinct nonlinear forms only occur at intensities where the beam-induced refractive index profile in the medium slowly evolves from a Gaussian to a flattened Gaussian. PMID:21934919

  11. Fermilab Booster Operational Status: Beam Loss and Collimation

    NASA Astrophysics Data System (ADS)

    Webber, Robert C.

    2002-12-01

    Beam loss reduction and control challenges confronting the Fermilab Booster are presented in the context of the current operational status. In Summer 2002 the programmatic demand for 8 GeV protons will increase to 5E20/year. This is an order of magnitude above recent high rates and nearly as many protons as the machine has produced in its entire 30-year lifetime. Catastrophic radiation damage to accelerator components must be avoided, maintenance in an elevated residual radiation environment must be addressed, and operation within a tight safety envelope must be conducted to limit prompt radiation in the buildings and grounds around the Booster. Diagnostic and performance tracking improvements, enhanced orbit control, and a beam loss collimation/localization system are essential elements in the approach to achieving the expected level of performance and are described here.

  12. Parameters of the ring dislocation of a degree of coherence of the vortex Bessel beam in turbulent atmosphere

    NASA Astrophysics Data System (ADS)

    Lukin, Igor P.

    2015-11-01

    In this paper results of theoretical consideration of behavior of degree of coherence of the coherent vortex Bessel optical beam propagating in turbulent atmosphere are presented. It is shown, that at low levels of fluctuations, in the central part of a two-dimensional field of degree of coherence of the vortex Bessel optical beams the ring dislocation is formed, the number of rings in which is equal to value of a topological charge of an optical beam. The structure of a ring dislocation of degree of coherence of the vortex Bessel optical beams in turbulent atmosphere is studied in detail. For this purpose two characteristics of a ring dislocation are entered: its spatial coordinates and width of a ring. Influence of parameters of an optical beam (a cross-section wave number and a topological charge) and atmospheric turbulence on these characteristics of a ring dislocation of degree of coherence of the vortex Bessel optical beam is considered.

  13. Ring artifacts removal via spatial sparse representation in cone beam CT

    NASA Astrophysics Data System (ADS)

    Li, Zhongyuan; Li, Guang; Sun, Yi; Luo, Shouhua

    2016-03-01

    This paper is about the ring artifacts removal method in cone beam CT. Cone beam CT images often suffer from disturbance of ring artifacts which caused by the non-uniform responses of the elements in detectors. Conventional ring artifacts removal methods focus on the correlation of the elements and the ring artifacts' structural characteristics in either sinogram domain or cross-section image. The challenge in the conventional methods is how to distinguish the artifacts from the intrinsic structures; hence they often give rise to the blurred image results due to over processing. In this paper, we investigate the characteristics of the ring artifacts in spatial space, different from the continuous essence of 3D texture feature of the scanned objects, the ring artifacts are displayed discontinuously in spatial space, specifically along z-axis. Thus we can easily recognize the ring artifacts in spatial space than in cross-section. As a result, we choose dictionary representation for ring artifacts removal due to its high sensitivity to structural information. We verified our theory both in spatial space and coronal-section, the experimental results demonstrate that our methods can remove the artifacts efficiently while maintaining image details.

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

    SciTech Connect

    Robert-Demolaize,G.; Drees, A.

    2008-06-23

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

  15. Beam Tests of a Clearing Electrode for Electron Cloud Mitigation at KEKB Positron Ring

    SciTech Connect

    Suetsugu, Y.; Fukuma, H.; Shibata, K.; Pivi, M.; Wang, L.; /SLAC

    2010-06-15

    In order to mitigate the electron cloud instability in an intense positron ring, an electron clearing electrode with a very thin structure has been developed. The electrode was tested with a positron beam of the KEKB B-factory (KEKB). A drastic reduction in the electron density around the beam was demonstrated in a wiggler magnet with a dipole-type magnetic field of 0.78 T. The clearing electrode was then applied to a copper beam pipe with antechambers assuming an application of the electrode to a wiggler section in the Super KEKB. The beam pipe was installed at a magnetic-free region in the ring and tested with beam. No extra heating of the electrodes and feed-throughs were observed. A reduction in the electron density reasonable in a magnetic-free region was also obtained.

  16. Rapid Cycling Synchrotrons and Accumulator Rings for High-Intensity Hadron Beams

    NASA Astrophysics Data System (ADS)

    Tang, Jingyu

    2014-02-01

    Boosted by the needs in high-energy physics and nuclear physics and also multidisciplinary applications, high-intensity proton synchrotrons and accumulator rings have been developed quickly around the world over the last 30 years. New projects and plans are proposed with even higher beam power. The proton beam power has increased from less than 10 kW in the 1970s to about 1 MW level today, and the required beam power in the coming decade is a few MW. This article reviews the achievements in designing and constructing rapid cycling synchrotrons (RCSs) and accumulator rings (ARs) and the future development trends, principally on proton beams but also including heavy ion beams. It presents the evolution of RCS and AR machines, today's design philosophy, relevant accelerator physics, and also state-of-the-art accelerator technology.

  17. Interstellar He+ Ring-Beam Distributions: Observations and Implications

    NASA Astrophysics Data System (ADS)

    Drews, C.; Berger, L.; Wimmer-Schweingruber, R. F.; Galvin, A. B.

    2013-12-01

    Interstellar pickup ions, which are believed to be injected as a ring-like velocity distributions into the bulk solar wind, are exposed to fluctuations of the Interplanetary Magnetic Field (IMF) and thus undergo pitch-angle scattering. It is generally assumed that this process can be very efficient on short time scales, and thus velocity distributions of pickup ions were believed to be fully isotropic in nature [Vasyliunas and Siscoe, 1976]. However, unambiguous evidence for this assumption has yet to be found. Indeed, observations of reduced one-dimensional w-spectra for quasi-parallel and -perpendicular IMF orientations revealed a significant difference in flux and spectral shape of interstellar He+ pickup ions, which e.g., Saul et al. [2007], Möbius et al. [1998], and Isenberg [1997] attributed to ineffective scattering across 90° pitch-angle. Here we report systematic measurements of the distribution of the incident angle of interstellar pickup He+ ions as observed by STEREO/Plasma and Supra-Thermal Ion Composition (PLASTIC). We have organized these observations according to the angle spanned by the IMF vector, B, and the solar wind velocity vector. Our measurements show clear evidence of a relatively local injection of He+ pickup ions into the solar wind, which are then seen as a ring distribution perpendicular to B. Changes of the spectral shape and a reduced flux of interstellar He+ during radial IMF configuration, as observed by, e.g., Ulysses/Solar Wind Ion Composition Spectrometer (SWICS), SOHO/Charge Time-Of-Flight (CTOF), Active Magnetospheric Particle Tracer Explorers/SUprathermaL Energy Ionic Charge Analyzer (SULEICA), have generally been attributed to inefficient scattering across 90° pitch-angle. Our observations of the pitch-angle distribution of interstellar He+ suggest that these changes are instead a result of locally injected pickup ions that escape detection for IMF configuration in which the Solar Wind Sector of PLASTIC, as well as SWICS

  18. Beam losses and beam halos in accelerators for new energy sources

    SciTech Connect

    Jameson, R.A.

    1995-12-31

    Large particle accelerators are proposed as drivers for new ways to produce electricity from nuclear fusion and fission reactions. The accelerators must be designed to deliver large particle beam currents to a target facility with very little beam spill along the accelerator itself, in order that accelerator maintenance can be accomplished without remote manipulators. Typically, particle loss is preceded by the formation of a tenuous halo of particles around the central beam core, caused by beam dynamics effects, often coupled with the slight imperfections inevitable in a practical design. If the halo becomes large enough, particles may be scraped off along the accelerator. The tolerance for beam spill in different applications is discussed, halo mechanisms and recent work to explore and understand their dynamics are reviewed, and possible directions for future investigation are outlined. 17 refs., 10 figs.

  19. Feasibility Study of Compact Gas-Filled Storage Ring for 6D Cooling of Muon Beams

    SciTech Connect

    A. Garren, J. Kolonlo

    2005-10-31

    The future of elementary particle physics in the USA depends in part on the development of new machines such as the International Linear Collider, Muon Collider and Neutrino Factories which can produce particle beams of higher energy, intensity, or particle type than now exists. These beams will enable the continued exploration of the world of elementary particles and interactions. In addition, the associated development of new technologies and machines such as a Muon Ring Cooler is essential. This project was to undertake a feasibility study of a compact gas-filled storage ring for 6D cooling of muon beams. The ultimate goal, in Phase III, was to build, test, and operate a demonstration storage ring. The preferred lattice for the storage ring was determined and dynamic simulations of particles through the lattice were performed. A conceptual design and drawing of the magnets were made and a study of the RF cavity and possible injection/ejection scheme made. Commercial applications for the device were investigated and the writing of the Phase II proposal completed. The research findings conclude that a compact gas-filled storage ring for 6D cooling of muon beams is possible with further research and development.

  20. Conceptual design of a linac-stretcher ring to obtain a 2-GeV continuous electron beam

    SciTech Connect

    Cho, Y.; Holt, R.J.; Jackson, H.E.; Khoe, T.K.; Mavrogenes, G.S.

    1981-01-01

    In order to obtain a high duty factor, > 100 ..mu..A 2-GeV electron beam, we have designed a linac-stretcher ring system. The system is an attractive option because it draws heavily on the existing accelerator technology. The linac-stretcher ring consists of a 2-GeV SLAC-type pulsed linac which injects into a storage ring. In between linac pulses, the stored electron beam is to extract resonantly. This design differs from those discussed recently in several important respects. The storage ring includes an RF system whose purpose is to control the beam orbit and rate of extraction from the ring. With an RF system in the ring, the injection scheme consists of a few turns of synchronous transfers of beam between the linac and storage ring.

  1. The University of Maryland Electron Ring: A Model Recirculator for Intense Beam Physics Research

    SciTech Connect

    Bernal, S.; Li, H.; Cui, Y.; Feldman, D.; Godlove, T.; Haber, I.; Huo, Y.; Harris, J.; Kishek, R.A.; Quinn, B.; Reiser, M.; Walter, M.; Wilson, M.; Zou, Y.; O'Shea, P.G.

    2004-12-07

    The University of Maryland Electron Ring (UMER), designed for transport studies of space-charge dominated beams in a strong focusing lattice, is nearing completion. Low energy, high intensity electron beams provide an excellent model system for experimental studies with relevance to all areas that require high quality, intense charged-particle beams. In addition, UMER constitutes an important tool for benchmarking of computer codes. When completed, the UMER lattice will consist of 36 alternating-focusing (FODO) periods over an 11.5-m circumference. Current studies in UMER over about 2/3 of the ring include beam-envelope matching, halo formation, asymmetrical focusing, and longitudinal dynamics (beam bunch erosion and wave propagation.) Near future, multi-turn operation of the ring will allow us to address important additional issues such as resonance-traversal, energy spread and others. The main diagnostics are phosphor screens and capacitive beam position monitors placed at the center of each 200 bending section. In addition, pepper-pot and slit-wire emittance meters are in operation. The range of beam currents used corresponds to space charge tune depressions from 0.2 to 0.8, which is unprecedented for a circular machine.

  2. BEAM EXTRACTION FROM THE SNS RING AND DESIGN OF EXTRACTION KICKERS.

    SciTech Connect

    TSOUPAS, N.; BLASKIEWICZ, M.; LEE, Y.Y.; MI, J.L.; SOUKAS, A.; WANG, J.G.; WEI, J.; ZHANG, S.Y.

    2000-06-30

    The accumulator ring of the Spallation Neutron Source (SNS) [1] will accumulate a proton beam, injected from a LINAC, into a single bunch containing {approximately} 2.1 x 10{sup 14} protons at a maximum energy of 1.3 GeV. The single bunch with length {approximately}650 nsec and a gap of {approximately}290 nsec will circulate into the accumulator ring for {approximately}1.0 msec before it is extracted into the RTBT transfer line. The accumulation, extraction frequency is set at 60 Hz. This paper discusses the extraction process and the requirements of the fast beam extraction system.

  3. INCREASED UNDERSTANDING OF BEAM LOSSES FROM THE SNS LINAC PROTON EXPERIMENT

    SciTech Connect

    Aleksandrov, Alexander V; Shishlo, Andrei P; Plum, Michael A; Lebedev, Valerie; Laface, Emanuele; Galambos, John D

    2013-01-01

    Beam loss is a major concern for high power hadron accelerators such as the Spallation Neutron Source (SNS). An unexpected beam loss in the SNS superconducting linac (SCL) was observed during the power ramp up and early operation. Intra-beam-stripping (IBS) loss, in which interactions between H- particles within the accelerated bunch strip the outermost electron, was recently identified as a possible cause of the beam loss. A set of experiments using proton beam acceleration in the SNS linac was conducted, which supports IBS as the primary beam loss mechanism in the SNS SCL.

  4. Losses of ion energy in the multicomponent beam

    NASA Astrophysics Data System (ADS)

    Gasanov, Ilkham S.; Gurbanov, Ilgar I.; Akbarov, Elchin M.

    2015-03-01

    Energy losses of near axis ions and decreases in ion current density in the center of a beam were observed in a liquid metal source operating under a charged nanodroplets (In, Sn, Au, Ge) generation regime. In experiments, nanodroplets with the sizes of 2-20 nanometers and a characteristic specific charge of 5 × 104 C/kg were revealed. Energy spectra of ions were defined by means of the filter of speeds with cross-section static electromagnetic fields. A reduction of 4% of the In+ ions energy was observed under the conditions of the curried out measurements. The stream of nanoparticles, in contrast to an ion beam, has a small radial divergence; outside of this stream, change of ion speeds is not observed. Energy losses of ions occur during their flight through small nanoparticles. Penetration depth of the accelerated ions in liquid indium is estimated within the framework of the Lindhard-Scharff-Schiott model. Similar interaction between components occurs in ion-beam systems of complex composition where there is a relative movement of various charged particles.

  5. Interstellar He+ ring-beam distributions: Observations and implications

    NASA Astrophysics Data System (ADS)

    Drews, C.; Berger, Lars; Wimmer-Schweingruber, Robert F.; Galvin, Antoinette B.

    2013-04-01

    We report systematic measurements of the distribution of the incident angle of interstellar pickup He+ ions as observed by STEREO/Plasma and Supra-Thermal Ion Composition (PLASTIC). We have organized these observations according to the angle spanned by the Interplanetary Magnetic Field (IMF), B→, and the bulk solar wind velocity, vsw→. Our measurements show clear evidence of a relatively local injection of He+ pickup ions into the solar wind, which are then seen as a ring distribution perpendicular to B→. Changes of the spectral shape and a reduced flux of interstellar He+ during radial IMF configuration, as observed by, e.g., Ulysses/Solar Wind Ion Composition Spectrometer (SWICS), SOHO/Charge Time-Of-Flight (CTOF), Active Magnetospheric Particle Tracer Explorers/SUprathermaL Energy Ionic Charge Analyzer (SULEICA), have generally been attributed to inefficient scattering across 90° pitch-angle. Our observations of the pitch-angle distribution of interstellar He+ suggest that these changes are instead a result of locally injected pickup ions that escape detection for IMF configuration in which the Solar Wind Sector of PLASTIC, as well as SWICS, CTOF, and SULEICA, are not sensitive to the measurement of the locally injected pickup ion ring.

  6. The LCLS Undulator Beam Loss Monitor Readout System

    SciTech Connect

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

    2012-07-23

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

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

    SciTech Connect

    Rakhno, I.L.; Drozhdin, A.I.; Mokhov, N.V.; Sidorov, V.I.; Tropin, I.S.; /Fermilab

    2012-05-14

    A fast vertical 1.08-m long kicker (notcher) located in the Fermilab Booster Long-05 straight section is currently used to remove 3 out of 84 circulating bunches after injection to generate an abort gap. With the maximum magnetic field of 72.5 Gauss, it removes only 87% of the 3-bunch intensity at 400 MeV, with 75% loss on pole tips of the focusing Booster magnets, 11% on the Long-06 collimators, and 1% in the rest of the ring. We propose to improve the notching efficiency and reduce beam loss in the Booster by using three horizontal kickers in the Long-12 section. STRUCT calculations show that using horizontal notchers, one can remove up to 96% of the 3-bunch intensity at 400-700 MeV, directing 95% of it to a new beam dump at the Long-13 section. This fully decouples notching and collimation. The beam dump absorbs most of the impinging proton energy in its jaws. The latter are encapsulated into an appropriate radiation shielding that reduces impact on the machine components, personnel and environment to the tolerable levels. MARS simulations show that corresponding prompt and residual radiation levels can be reduced ten times compared to the current ones.

  8. Higher-order paraxial theory of the propagation of ring rippled laser beam in plasma: Relativistic ponderomotive regime

    SciTech Connect

    Purohit, Gunjan Rawat, Priyanka; Chauhan, Prashant; Mahmoud, Saleh T.

    2015-05-15

    This article presents higher-order paraxial theory (non-paraxial theory) for the ring ripple formation on an intense Gaussian laser beam and its propagation in plasma, taking into account the relativistic-ponderomotive nonlinearity. The intensity dependent dielectric constant of the plasma has been determined for the main laser beam and ring ripple superimposed on the main laser beam. The dielectric constant of the plasma is modified due to the contribution of the electric field vector of ring ripple. Nonlinear differential equations have been formulated to examine the growth of ring ripple in plasma, self focusing of main laser beam, and ring rippled laser beam in plasma using higher-order paraxial theory. These equations have been solved numerically for different laser intensities and plasma frequencies. The well established experimental laser and plasma parameters are used in numerical calculation. It is observed that the focusing of the laser beams (main and ring rippled) becomes fast in the nonparaxial region by expanding the eikonal and other relevant quantities up to the fourth power of r. The splitted profile of laser beam in the plasma is observed due to uneven focusing/defocusing of the axial and off-axial rays. The growths of ring ripple increase when the laser beam intensity increases. Furthermore, the intensity profile of ring rippled laser beam gets modified due to the contribution of growth rate.

  9. Amplification of electromagnetic waves by a ring-beam distribution of moderately relativistic electrons

    NASA Technical Reports Server (NTRS)

    Shi, B. R.; Gaffey, J. D., Jr.; Wu, C. S.

    1986-01-01

    The possibility of a new mechanism for the excitation of unstable modes in cold background plasmas is indicated in this paper. These beam-cyclotron modes are excited by the presence of the ring-beam distribution of suprathermal electrons. The usual eigenmode excitation of a cold plasma is reviewed, and the new type of instability is examined using a single-harmonic approximation and multiharmonic treatment.

  10. Beam loss ion chamber system upgrade for experimental halls

    SciTech Connect

    D. Dotson; D. Seidman

    2005-08-01

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

  11. Beam Loss Ion Chamber System Upgrade for Experimental Halls

    SciTech Connect

    D.W. Dotson; D.J. Seidman

    2005-05-16

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

  12. A parallel particle-in-cell model for beam-beam interaction in high energy ring colliders

    NASA Astrophysics Data System (ADS)

    Qiang, Ji; Furman, Miguel A.; Ryne, Robert D.

    2004-07-01

    In this paper we present a self-consistent simulation model of colliding beams in high energy ring colliders. The model, which is based on a particle-in-cell method, uses a new developed shifted effective Green function algorithm for the efficient calculation of the beam-beam interaction with arbitrary separation and large aspect ratio. The model uses transfer maps to treat the external focusing elements and a stochastic map to treat radiation damping and quantum excitation of the beams. In the parallel implementation we studied various strategies to deal with the particular nature of the colliding beam system - a system in which there can be significant particle movement between beam-beam collisions. We chose a particle-field decomposition approach instead of the conventional domain decomposition or particle decomposition approach. The particle-field approach leads to good load balance, reduced communication cost, and shows the best scalability on an IBM SP3 among the three parallel implementations we studied. A performance test of the beam-beam model on a Cray T3E, IBM SP3, and a PC cluster is presented. As an application, we studied the flip-flop instability in an electron-positron collider.

  13. Transition from ring to beam arc distributions of water ions near the Space Shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.

    1990-01-01

    The distribution function of water ions produced near the Space Shuttle by charge exchange between ionospheric oxygen ions and outgassed water molecules is studied. The transition from a ring to a beam arc distribution function is described. The number density of water ions is found to increase monotonically with decreasing distance from the Shuttle.

  14. Colliding or co-rotating ion beams in storage rings for EDM search

    NASA Astrophysics Data System (ADS)

    Koop, I. A.

    2015-11-01

    A new approach to search for and measure the electric dipole moment (EDM) of the proton, deuteron and some other light nuclei is presented. The idea of the method is to store two ion beams, circulating with different velocities, in a storage ring with crossed electric and magnetic guiding fields. One beam is polarized and its EDM is measured using the so-called ‘frozen spin’ method. The second beam, which is unpolarized, is used as a co-magnetometer, sensitive to the radial component of the ring’s magnetic field. The particle’s magnetic dipole moment (MDM) couples to the radial magnetic field and mimics the EDM signal. Measuring the relative vertical orbit separation of the two beams, caused by the presence of the radial magnetic field, one can control the unwanted MDM spin precession. Examples of the parameters for EDM storage rings for protons and other species of ions are presented. The use of crossed electric and magnetic fields helps to reduce the size of the ring by a factor of 10-20. We show that the bending radius of such an EDM storage ring could be about 2-3 m. Finally, a new method of increasing the spin coherence time, the so-called ‘spin wheel’, is proposed and its applicability to the EDM search is discussed.

  15. Beam size measurement of the stored electron beam at the APS storage ring using zone plate optics and undulator radiation

    SciTech Connect

    Cai, Z.; Lai, B.; Yun, W.

    1997-10-01

    Beam sizes of the stored electron beam at the Advanced Photon Source storage ring were measured using zone-plate optics and undulator radiation. A gold Fresnel zone plate (3.5 {micro}m thick) located 33.9 meters from the x-ray source focused radiation of 18 keV, selected by a cryogenically cooled Si(111) crystal in horizontal deflection, and formed a source image in a transverse plane 2.41 m downstream. The sizes of the source image were determined from measured intensity profiles of x-ray fluorescence from a smooth nickel edge (1.5 {micro}m thick), fabricated using a lithographic technique, while the nickel edge was scanned across over the beam in the transverse plane. The measured vertical and horizontal sizes of the electron beam were 60 {+-} 4.3 {micro}m and 300 {+-} 13 {micro}m, respectively, in reasonable agreement with the expected values.

  16. Ring artifact corrections in flat-panel detector based cone beam CT

    NASA Astrophysics Data System (ADS)

    Anas, Emran Mohammad Abu; Kim, Jaegon; Lee, Soo Yeol; Hasan, Md. Kamrul

    2011-03-01

    The use of flat-panel detectors (FPDs) is becoming increasingly popular in the cone beam volume and multi-slice CT imaging. But due to the deficient semiconductor array processing, the diagnostic quality of the FPD-based CT images in both CT systems is degraded by different types of artifacts known as the ring and radiant artifacts. Several techniques have been already published in eliminating the stripe artifacts from the projection data of the multi-slice CT system or in other words, from the sinogram image with a view to suppress the ring and radiant artifacts from the 2-D reconstructed CT images. On the other hand, till now a few articles have been reported to remove the artifacts from the cone beam CT images. In this paper, an effective approach is presented to eliminate the artifacts from the cone beam projection data using the sinogram based stripe artifact removal methods. The improvement in the required diagnostic quality is achieved by applying them both in horizontal and vertical sinograms constituted sequentially from the stacked cone beam projections. Finally, some real CT images have been used to demonstrate the effectiveness of the proposed technique in eliminating the ring and radiant artifacts from the cone beam volume CT images. A comparative study with the conventional sinogram based approaches is also presented to see the effectiveness of the proposed technique.

  17. Spatial profile of laser beam in antiresonant ring cavity: experimental study

    NASA Astrophysics Data System (ADS)

    Grabovski, Vitaly V.; Prokhorenko, Valentin I.; Yatskiv, Dmytro Y.

    1996-03-01

    This paper presents results of experimental studies of the spatial profile of the beam in lasers with an antiresonant ring. The near-field profile of the beam was measured by the pin-hole technique. In case of the active crystal placed into the ring, the beam profile was found to be Gaussian within a wide range of the pumping power. Variation of the width of the Gaussian profile is caused by the thermal lens in the active crystal. Measurements of the FWHM of the Gaussian profile demonstrated that it is proportional to the one-fourth power of the focal length of the thermal lens, as in the case of a stable cavity.

  18. Beam Ion Instability in ILC Damping Ring with Multi-Gas Species

    SciTech Connect

    Wang, Lanfa; Pivi, Mauro; /SLAC

    2012-05-30

    Ion induced beam instability is one critical issue for the electron damping ring of the International Linear Collider (ILC) due to its ultra small emittance of 2 pm. The beam ion instability with various beam filling patterns for the latest lattice DTC02 is studied using PIC code. The code has been benchmarked with SPEAR3 experimental data and there is a good agreement between the simulation and observations. It uses the optics from MAD and can handle arbitrary beam filling pattern and vacuum. Different from previous studies, multi-gas species and exact beam filling patterns have been modeled simultaneously in the study. This feature makes the study more realistic. Analyses have been done to compare with the simulations.

  19. Loss of Water from Saturn's E-Ring Through Ion Pick-Up

    NASA Technical Reports Server (NTRS)

    Leisner, J. S.; Russell, C. T.; Dougherty, M. K.; Blanco-Cano, X.; Smith, E. J.; Tsurutani, B. T.

    2005-01-01

    One of the possible loss processes for Saturn s E-ring is ionization followed by acceleration by the electric field associated with the corotating magnetized plasma. It is possible to determine if this process is occurring by detecting electromagnetic waves at the gyrofrequency of water group ions. If the energy the particle gains in this pick-up process is sufficiently great, the picked up ions will generate ion cyclotron waves. Pioneer 11 and Voyager 1 both observed intervals of such waves associated with water group ions during their passes through Saturn s E-ring. Presently the magnetometer onboard the Cassini spacecraft is also seeing water group ion cyclotron oscillations. The Cassini data allow the spatial and temporal behavior of the waves to be mapped in ways not possible during the previous flybys. Analyses of these waves allow us to study the rate of mass loading and its latitudinal and local time variation. In conjunction with previous data, we can then determine the variation as the inclination of the ring to the Sun changes, in accordance with Saturn's seasons. These waves may be the clue to how Saturn powers its magnetosphere as the newly born ions could be the driver for the radial motion of the plasma and to how the E-ring may play the equivalent role to that of Io in the jovian magnetosphere.

  20. Overcoming the losses of a split ring resonator array with gain

    SciTech Connect

    Fang Anan; Huang Zhixiang; Koschny Thomas; Soukoulis Costas M

    2011-06-16

    We present a computational approach, allowing for a self-consistent treatment of a split ring resonator (SRR) array with a gain layer underneath. We apply three different pumping schemes on the gain layer: (1) homogeneously pumped isotropic gain, (2) homogeneously pumped isotropic gain with a shadow cast by the SRR and (3) anisotropic gain pumped in a selected direction only. We show numerically the magnetic losses of the SRR can be compensated by the gain. The difference on loss compensations among the three pumping schemes is analyzed by the electric field distribution. Studies also show the dielectric background of gain does not affect the loss compensation much for the gain only pumped in the direction parallel to the SRR plane.

  1. Observation of longitudinal diffusion and cooling due to intra-beam scattering at the Fermilab Recycler Ring

    SciTech Connect

    Hu, M.; Nagaitsev, S.; /Fermilab

    2005-05-01

    The Fermilab Recycler Ring is a high-vacuum fixed energy antiproton storage ring with both stochastic (at present) and the future electron cooling systems. In this paper the technique for diffusion rate measurement, beam parameters and the analysis of data are presented, as well as the effect of intra-beam scattering on the operational considerations for the storage and cooling of the antiproton beam in the Recycler.

  2. Beam uniformization and low frequency RF cavities in compact electron storage rings

    NASA Astrophysics Data System (ADS)

    Pham, Alfonse N.

    An electron storage ring is currently under construction at Indiana University for extreme environment radiation effects experiments, x-ray production, and particle beam dynamics experiments. For an electron bunch to be successfully stored for long durations, a radio-frequency (RF) resonant structure will be used to provide an adequate RF bucket for longitudinal focusing and replenishment of energy electrons loses via synchrotron radiation. Due to beam line space limitation that are inherent to compact circular particle accelerators, a unique ferrite-loaded quarter-wave RF resonant cavity has been designed and constructed for use in the electron storage ring. The physics of particle accelerators and beams, ferrite-loaded RF resonant cavity theory, and results of the Poisson-SUPERFISH electromagnetic field simulations that were used to guide the specification and design of the RF cavity will be presented. Low-power resonant cavity characterization measurements were used to benchmark the performance of the RF cavity. High-power characterization and measurements with electron beams will be used to validate the performance of the cavity in the electron storage ring. To fulfill the requirements for radiation effect experiments, the storage ring manipulation of beams that utilizes a phase space beam dilution method have been developed for the broadening of the radiation damped electron bunch with longitudinal particle distribution uniformity. The method relies on phase modulation applied to a double RF system to generate large regions of bounded chaotic particle motion in phase space. These region are formed by a multitude of overlapping parametric resonances. Parameters of the double RF system and applied phase modulation can be adjusted to vary the degree of beam dilution. The optimal RF parameters have been found for maximal bunch broadening, uniform longitudinal particle distribution, and bounded particle diffusion. Implementation of the phase space dilution method

  3. Precision analog signal processor for beam position measurements in electron storage rings

    SciTech Connect

    Hinkson, J.A.; Unser, K.B.

    1995-05-01

    Beam position monitors (BPM) in electron and positron storage rings have evolved from simple systems composed of beam pickups, coaxial cables, multiplexing relays, and a single receiver (usually a analyzer) into very complex and costly systems of multiple receivers and processors. The older may have taken minutes to measure the circulating beam closed orbit. Today instrumentation designers are required to provide high-speed measurements of the beam orbit, often at the ring revolution frequency. In addition the instruments must have very high accuracy and resolution. A BPM has been developed for the Advanced Light Source (ALS) in Berkeley which features high resolution and relatively low cost. The instrument has a single purpose; to measure position of a stable stored beam. Because the pickup signals are multiplexed into a single receiver, and due to its narrow bandwidth, the receiver is not intended for single-turn studies. The receiver delivers normalized measurements of X and Y posit ion entirely by analog means at nominally 1 V/mm. No computers are involved. No software is required. Bergoz, a French company specializing in precision beam instrumentation, integrated the ALS design m their new BPM analog signal processor module. Performance comparisons were made on the ALS. In this paper we report on the architecture and performance of the ALS prototype BPM.

  4. First storage of ion beams in the Double Electrostatic Ion-Ring Experiment: DESIREE

    SciTech Connect

    Schmidt, H. T.; Thomas, R. D.; Gatchell, M.; Rosen, S.; Reinhed, P.; Loefgren, P.; Braennholm, L.; Blom, M.; Bjoerkhage, M.; Baeckstroem, E.; Alexander, J. D.; Leontein, S.; Zettergren, H.; Liljeby, L.; Kaellberg, A.; Simonsson, A.; Hellberg, F.; Mannervik, S.; Larsson, M.; Geppert, W. D.; and others

    2013-05-15

    We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (C{sub n}{sup -}, n= 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV C{sub 2}{sup -} molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s {+-} 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10{sup -14} mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.

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

    NASA Astrophysics Data System (ADS)

    Liu, Ning

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

  6. Compact and broadband circularly polarized ring antenna with wide beam-width for multiple global navigation satellite systems

    NASA Astrophysics Data System (ADS)

    Zhang, Hong-Lin; Hu, Bin-Jie; Zhang, Xiu-Yin

    2012-02-01

    A compact and broadband circularly polarized (CP) annular ring antenna with wide beam-width is proposed for multiple global navigation satellite systems (GNSS) in the L1 band. The annular ring is excited by two modified L-probes with quadrature phase difference. It has a 36.3% 10-dB return loss bandwidth and a 13% 3-dB axial ratio bandwidth, because of the orthogonal L-probes with 90° phase difference. The measured peak gain of the antenna is 3.9 dBic. It can detect the satellites at lower elevation as its half power beam-width (HPBW) is 113° in both the x—z and y—z planes, achieving a cross-polarization level of larger than 25 dB. Noticeably, the antenna achieves 89% size reduction compared with the conventional half wavelength patch antennas. It can be used in hand-held navigation devices of multiple GNSS such as COMPASS, Galileo, GPS and GLONASS.

  7. Oxygen gas-sheet beam profile monitor for the synchrotron and storage ring

    NASA Astrophysics Data System (ADS)

    Hashimoto, Y.; Fujisawa, T.; Morimoto, T.; Fujita, Y.; Honma, T.; Muto, S.; Noda, K.; Sato, Y.; Yamada, S.

    2004-07-01

    A fast, non-destructive beam-profile monitor was developed using an oxygen gas-sheet target in the Heavy Ion Medical Accelerator in Chiba synchrotron. The size of the gas-sheet target was 85 mm in width and 1.3 mm in thickness, of which the density was 1×10 -4 Pa. The base vacuum in the ring was not deteriorated by this gas-sheet target, and was on the order of 10 -8 Pa. In typical cases, carbon ion beams are accelerated from 6 to 290-430 MeV/n for cancer therapy, in which the intensity is 2.5×10 8 particles/bunch. For these beams, two-dimensional beam profiles were successfully measured within the time (˜100 ns) of the bunch separation. This article describes both the technical and physical aspects of the monitor together with some results.

  8. Beam pinging, sweeping, shaking, and electron/ion collecting, at the Proton Storage Ring

    SciTech Connect

    Hardek, T.W.; Macek, R.J.; Plum, M.A.; Wang, T.S.F.

    1993-01-01

    We have built, installed and tested a pinger for use as a general diagnostic at the Los Alamos Proton Storage Ring (PSR). Two 4-m-long parallel-plate electrodes with a plate spacing of 10.2 cm provide kicks of up to 1.1 mrad. A pair of solid-state pulsers may be operated in a single-pulse mode for beam pinging (tune measurements) or in a burst mode at up to 700 kHz pulse rates for beam sweeping. During our 1992 operating period we used the pinger for beam sweeping, for beam shaking, for measuring the tune shift, and we have used it as an ion chamber. Using the pinger as an ion chamber during production conditions has yielded some surprising results.

  9. Beam pinging, sweeping, shaking, and electron/ion collecting, at the Proton Storage Ring

    SciTech Connect

    Hardek, T.W.; Macek, R.J.; Plum, M.A.; Wang, T.S.F.

    1993-06-01

    We have built, installed and tested a pinger for use as a general diagnostic at the Los Alamos Proton Storage Ring (PSR). Two 4-m-long parallel-plate electrodes with a plate spacing of 10.2 cm provide kicks of up to 1.1 mrad. A pair of solid-state pulsers may be operated in a single-pulse mode for beam pinging (tune measurements) or in a burst mode at up to 700 kHz pulse rates for beam sweeping. During our 1992 operating period we used the pinger for beam sweeping, for beam shaking, for measuring the tune shift, and we have used it as an ion chamber. Using the pinger as an ion chamber during production conditions has yielded some surprising results.

  10. Storage Rings

    SciTech Connect

    Fischer, W.

    2011-01-01

    Storage rings are circular machines that store particle beams at a constant energy. Beams are stored in rings without acceleration for a number of reasons (Tab. 1). Storage rings are used in high-energy, nuclear, atomic, and molecular physics, as well as for experiments in chemistry, material and life sciences. Parameters for storage rings such as particle species, energy, beam intensity, beam size, and store time vary widely depending on the application. The beam must be injected into a storage ring but may not be extracted (Fig. 1). Accelerator rings such as synchrotrons are used as storage rings before and after acceleration. Particles stored in rings include electrons and positrons; muons; protons and anti-protons; neutrons; light and heavy, positive and negative, atomic ions of various charge states; molecular and cluster ions, and neutral polar molecules. Spin polarized beams of electrons, positrons, and protons were stored. The kinetic energy of the stored particles ranges from 10{sup -6} eV to 3.5 x 10{sup 12} eV (LHC, 7 x 10{sup 12} eV planned), the number of stored particles from one (ESR) to 1015 (ISR). To store beam in rings requires bending (dipoles) and transverse focusing (quadrupoles). Higher order multipoles are used to correct chromatic aberrations, to suppress instabilities, and to compensate for nonlinear field errors of dipoles and quadrupoles. Magnetic multipole functions can be combined in magnets. Beams are stored bunched with radio frequency systems, and unbunched. The magnetic lattice and radio frequency system are designed to ensure the stability of transverse and longitudinal motion. New technologies allow for better storage rings. With strong focusing the beam pipe dimensions became much smaller than previously possible. For a given circumference superconducting magnets make higher energies possible, and superconducting radio frequency systems allow for efficient replenishment of synchrotron radiation losses of large current electron or

  11. An ion-beam injection line for the ELASR storage ring at KACST

    NASA Astrophysics Data System (ADS)

    El Ghazaly, M. O. A.; Behery, S. A.; Almuqhim, A. A.; Almalki, M. H.; Alshammari, S. M.; Alrashdi, A. O.; Alamer, H. S.; Jabr, A. S.; Lanazi, A. Z.

    2016-01-01

    A versatile ion injector beam-line has been developed for the specific use in the multi-purpose low-energy, storage ring facility at the King Abdulaziz City for Sciences and Technology (KACST) in Riyadh, Saudi Arabia. It incorporates a purpose-developed, high-resolution mass analyzing magnet and it is thereby dedicated to provide the ELASR storage ring with beams of ions of specific mass. It is also intended to operate independently as a single-pass experiment. This versatile ion-injection line was constructed in a staged approach, in which an axial injection version was built first, commissioned and is currently operating. The injection line in its final design is now being assembled and commissioned at KACST.

  12. Comb-assisted cavity ring-down spectroscopy of a buffer-gas-cooled molecular beam.

    PubMed

    Santamaria, Luigi; Sarno, Valentina Di; Natale, Paolo De; Rosa, Maurizio De; Inguscio, Massimo; Mosca, Simona; Ricciardi, Iolanda; Calonico, Davide; Levi, Filippo; Maddaloni, Pasquale

    2016-06-22

    We demonstrate continuous-wave cavity ring-down spectroscopy of a partially hydrodynamic molecular beam emerging from a buffer-gas-cooling source. Specifically, the (ν1 + ν3) vibrational overtone band of acetylene (C2H2) around 1.5 μm is accessed using a narrow-linewidth diode laser stabilized against a GPS-disciplined rubidium clock via an optical frequency comb synthesizer. As an example, the absolute frequency of the R(1) component is measured with a fractional accuracy of ∼1 × 10(-9). Our approach represents the first step towards the extension of more sophisticated cavity-enhanced interrogation schemes, including saturated absorption cavity ring-down or two-photon excitation, to buffer-gas-cooled molecular beams. PMID:27273337

  13. Beam loss by collimation in a neutralizer duct

    SciTech Connect

    Hamilton, G.W.; Willmann, P.A.

    1980-04-03

    Beam fractions lost by collimation in a neutralizer duct are computed in x-x' phase space by using three examples of slab beam distributions under a broad range of duct dimensions, beam half-widths, and beam divergences. The results can be used to design compact neutralizers and to specify beam requirements. The computer code ILOST can be used under a broad range of beam conditions to compute the fraction lost by collimation.

  14. Progress on optimization of the nonlinear beam dynamics in the MEIC collider rings

    SciTech Connect

    None, None

    2015-07-13

    One of the key design features of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab is a small beta function at the interaction point (IP) allowing one to achieve a high luminosity of up to 1034 cm-2s-1. The required strong beam focusing unavoidably causes large chromatic effects such as chromatic tune spread and beam smear at the IP, which need to be compensated. This paper reports recent progress in our development of a chromaticity correction scheme for the ion ring including optimization of dynamic aperture and momentum acceptance.

  15. Progress on Optimization of the Nonlinear Beam Dynamics in the MEIC Collider Rings

    SciTech Connect

    Morozov, Vasiliy S.; Derbenev, Yaroslav S.; Lin, Fanglei; Pilat, Fulvia; Zhang, Yuhong; Cai, Y.; Nosochkov, Y. M.; Sullivan, Michael; Wang, M.-H.; Wienands, Uli

    2015-09-01

    One of the key design features of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab is a small beta function at the interaction point (IP) allowing one to achieve a high luminosity of up to 1034 cm-2s-1. The required strong beam focusing unavoidably causes large chromatic effects such as chromatic tune spread and beam smear at the IP, which need to be compensated. This paper reports recent progress in our development of a chromaticity correction scheme for the ion ring including optimization of dynamic aperture and momentum acceptance.

  16. Nitride ion beam mixing of piston rings for high temperature diesel engine

    SciTech Connect

    Bryzik, W.; Kamo, R.; Woods, M.

    1995-05-01

    Direct ion implantation and ion beam mixing surface treatment processes are being explored to enhance the friction and wear characteristics of piston rings for the adiabatic diesel engine. Bench test results to temperatures of 540{degrees}C indicate that titanium nitride and chrome nitride ion beam mixing of M2 steel produces superior friction and wear properties compared to traditional plasma-sprayed chrome oxide and chrome carbide coatings. Friction was reduced by factor of two and wear was reduced by a factor of 20. 10 refs., 9 figs., 1 tab.

  17. Ring beam shaping optics fabricated with ultra-precision cutting for YAG laser processing

    NASA Astrophysics Data System (ADS)

    Kuwano, Ryoichi; Koga, Toshihiko; Tokunaga, Tsuyoshi; Wakayama, Toshitaka; Otani, Yukitoshi; Fujii, Nobuyuki

    2012-03-01

    In this study, a method for generating ring intensity distribution at a refraction-type lens with an aspheric element was proposed, and the beam shaping optical element was finished using only ultra-precision cutting. The shape of the optical element and its irradiance pattern were determined from numerical calculation based on its geometrical and physical optics. An ultra-precision lathe was employed to fabricate beam shaping optical elements, and acrylic resin was used as the material. The transmittance of an optical element (a rotationally symmetrical body) with an aspheric surface fabricated using a single-crystal diamond tool was over 98%, and its surface roughness was 9.6 nm Ra. The method enabled the formation of a circular melting zone on a piece of stainless steel with a thickness of 300 μm through pulse YAG laser ( λ 1:06 μm) processing such that the average radius was 610 μm and the width was 100-200 μm. Circular processing using a ring beam shaping optical element can be realized by single-pulse beam irradiation without beam scanning.

  18. Analysis of longitudinal beam dynamics behavior and rf system operative limits at high-beam currents in storage rings

    NASA Astrophysics Data System (ADS)

    Mastorides, T.; Rivetta, C.; Fox, J. D.; van Winkle, D.; Teytelman, D.

    2008-06-01

    A dynamics simulation model is used to estimate limits of performance of the positron-electron project (PEP-II). The simulation captures the dynamics and technical limitations of the low level radio frequency (LLRF) system, the high-power rf components, and the low-order mode coupled-bunch longitudinal beam dynamics. Simulation results showing the effect of nonlinearities on the LLRF loops, and studies of the effectiveness of technical component upgrades are reported, as well as a comparison of these results with PEP-II measurements. These studies have led to the estimation of limits and determining factors in the maximum stored current that the low energy ring/high energy ring (LER/HER) can achieve, based on system stability for different rf station configurations and upgrades. In particular, the feasibility of the PEP-II plans to achieve the final goal in luminosity, which required an increase of the beam currents to 4 A for LER and 2.2 A for HER, is studied. These currents are challenging in part because they would push the longitudinal low-order beam mode stability to the limit, and the klystron forward power past a level of satisfactory margin. An acceptable margin is defined in this paper, which in turn determines the corresponding klystron forward power limitation.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

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

    SciTech Connect

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

    2014-02-15

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

  1. Measurement of the longitudinal parameters of an electron beam in a storage ring

    SciTech Connect

    Krinsky, S.

    1989-01-01

    We discuss the determination of the longitudinal parameters of a bunched beam of electrons or positrons circulating in a storage ring. From the analysis of the beam current observed at a fixed azimuthal location, one can learn much about the longitudinal behavior. We present an elementary analysis of the time-dependence of the current. In particular, we discuss the determination of the average current, bunch length, synchrotron oscillation frequency, and the coherent synchrotron oscillation modes associated with longitudinal instabilities. A brief discussion is also given of the incoherent synchrotron oscillations, or Schottky noise. We review the electromagnetic field traveling with a charge in uniform motion, and introduce some of the most common devices used to detect this field: capacitive pick-up, stripline monitor, and DC beam current transformer. Our paper is organized as follows: We discuss the analysis of the time-dependence of the beam current. Then, the measurement of the current is considered. Finally, we describe some measurements of energy spread and bunch lengthening made recently at SLAC on the SLC damping ring. 12 refs., 6 figs.

  2. Characterization of beam dynamics in the APS injector rings using time-resolved imaging techniques

    SciTech Connect

    Yang, B.X.; Lumpkin, A.H.; Borland, M.

    1997-06-01

    Images taken with streak cameras and gated intensified cameras with both time (longitudinal) and spatial (transverse) resolution reveal a wealth of information about circular accelerators. The authors illustrate a novel technique by a sequence of dual-sweep streak camera images taken at a high dispersion location in the booster synchrotron, where the horizontal coordinate is strongly correlated with the particle energy and the {open_quotes}top-view{close_quotes} of the beam gives a good approximation to the particle density distribution in the longitudinal phase space. A sequence of top-view images taken fight after injection clearly shows the beam dynamics in the phase space. We report another example from the positron accumulator ring for the characterization of its beam compression bunching with the 12th harmonic rf.

  3. Combined Laser and Electron Cooling of Bunched C3+ Ion Beams at the Storage Ring ESR

    SciTech Connect

    Schramm, U.; Bussmann, M.; Habs, D.; Kuehl, T.; Beller, P.; Franzke, B.; Nolden, F.; Steck, M.; Saathoff, G.; Reinhardt, S.; Karpuk, S.

    2006-03-20

    We report on first laser cooling studies of bunched beams of triply charged carbon ions stored at an energy of 1.46 GeV at the ESR (GSI). Despite for the high beam energy and charge state laser cooling provided a reduction of the momentum spread of one order of magnitude in space-charge dominated bunches as compared to electron cooling. For ion currents exceeding 10 {mu}A intra-beam-scattering losses could not be compensated by the narrow band laser system presently in use. Yet, no unexpected problems occurred encouraging the envisaged extension of the laser cooling to highly relativistic beams. At ESR, especially the combination with modest electron cooling provided three-dimensionally cold beams in the plasma parameter range of unity, where ordering effects can be expected and a still unexplained signal reduction of the Schottky signal is observed.

  4. Measurement of inner and/or outer profiles of pipes using ring beam devices

    NASA Astrophysics Data System (ADS)

    Wakayama, T.; Yoshizawa, T.

    2009-11-01

    Inner profile measurement is an important matter in such fields as medicine, dentistry and anthropology as well as mechanical engineering and industry. Here we propose a measurement method for inner diameter of pipes and/or holes. The key device in this technique is a ring beam device which consists of a conical mirror and a laser diode. And the fundamental principle is based on optical sectioning without any contact probe. The optically sectioned profile of an inner wall of a pipe-like object is analyzed to give the inner profile in addition to the inner diameter. This optical instrument with a simple and small configuration is now under development for practical uses. In the hitherto-tried experimental works, the availability of this instrument has been highly evaluated and usability for practical applications is expected, especially, for measurement and inspection of mechanical components and elements besides pipes. This ring beam device consisting of a conical mirror and a LD is assembled to form a disklike light beam sheet. We show measurement result of pipes and holes, and, at the same time, report a compact inner profile measuring instrument. Both the ring beam device and a miniaturized CCD camera are fabricated in a glass tube. Availability of this instrument is shown by measuring the inner profiles of various pipes. In response to this trial, there appeared a strong request that not only the internal but external profiles should be measured simultaneously. Therefore we propose an improved method for measuring the external profile in addition to the internal profile. In our arrangement, one pair of concaved conical mirrors is used for the external profile measurement. In combination with the inner profile measurement technique, simultaneous measurement of the inner and outer profiles becomes attainable. A measurement result on a bevel gear shows availability of newly proposed principle. Now we are aiming to realize simultaneous measurement of the internal

  5. Surface Area Loss and Increased Sphericity Account for the Splenic Entrapment of Subpopulations of Plasmodium falciparum Ring-Infected Erythrocytes

    PubMed Central

    Safeukui, Innocent; Buffet, Pierre A.; Perrot, Sylvie; Sauvanet, Alain; Aussilhou, Beatrice; Dokmak, Safi; Couvelard, Anne; Hatem, Dominique Cazals; Mohandas, Narla; David, Peter H.; Mercereau-Puijalon, Odile; Milon, Geneviève

    2013-01-01

    Ex vivo perfusion of human spleens revealed innate retention of numerous cultured Plasmodium falciparum ring-infected red blood cells (ring-iRBCs). Ring-iRBC retention was confirmed by a microsphiltration device, a microbead-based technology that mimics the mechanical filtering function of the human spleen. However, the cellular alterations underpinning this retention remain unclear. Here, we use ImageStream technology to analyze infected RBCs’ morphology and cell dimensions before and after fractionation with microsphiltration. Compared to fresh normal RBCs, the mean cell membrane surface area loss of trophozoite-iRBCs, ring-iRBCs and uninfected co-cultured RBCs (uRBCs) was 14.2% (range: 8.3–21.9%), 9.6% (7.3–12.2%) and 3.7% (0–8.4), respectively. Microsphilters retained 100%, ∼50% and 4% of trophozoite-iRBCs, ring-iRBCs and uRBCs, respectively. Retained ring-iRBCs display reduced surface area values (estimated mean, range: 17%, 15–18%), similar to the previously shown threshold of surface-deficient RBCs retention in the human spleen (surface area loss: >18%). By contrast, ring-iRBCs that successfully traversed microsphilters had minimal surface area loss and normal sphericity, suggesting that these parameters are determinants of their retention. To confirm this hypothesis, fresh normal RBCs were exposed to lysophosphatidylcholine to induce a controlled loss of surface area. This resulted in a dose-dependent retention in microsphilters, with complete retention occurring for RBCs displaying >14% surface area loss. Taken together, these data demonstrate that surface area loss and resultant increased sphericity drive ring-iRBC retention in microsphilters, and contribute to splenic entrapment of a subpopulation of ring-iRBCs. These findings trigger more interest in malaria research fields, including modeling of infection kinetics, estimation of parasite load, and analysis of risk factors for severe clinical forms. The determination of the threshold of

  6. Rings

    SciTech Connect

    Davis, R.L.

    1989-01-01

    The essence of vortex physics is that at certain low-energy scales elementary excitations of a point particle theory can behave like strings rather than particles. Vortices are the resulting string-like solutions; their thickness sets the distance scale beyond which physics is string-like rather than particle-like. String degrees of freedom are massless in the sense that excitations on a string can have an arbitrarily low frequency. Non-string degrees of freedom correspond to massive particles and are absent from the low energy spectrum. This article considers only field theories with vortices at low energies. The possible existence of a class of solitons in these vortex theories will be discussed. They are vortex rings: they are localized and finite in energy, and able to carry the quantum numbers of point particles. Rings are thus particle-like solutions of a vortex theory, which is itself a limit of a point particle field theory.

  7. Transition from ring to beam arc distributions of water ions near the space shuttle orbiter

    SciTech Connect

    Cairns, I.H. )

    1990-09-01

    The distribution function of water ions produced near the space shuttle by charge exchange between ionospheric oxygen ions and outgassed water molecules is investigated using solutions of Liouville's equation with a source term modeling the charge exchange process. A transition from ring distributions to beamlike distributions termed beam arc distributions is found with decreasing distance upstream from the orbiter. This beam arc distribution corresponds to a finite section of a ring distribution and not to a conventional beam distribution. The ratio of water ion number density to oxygen ion number density is calculated; typical values within 50 m of the shuttle are in excess of 2% with a maximum value of the order of 20% for nominal parameters, suggsting that these ions must be considered with interpreting particle data from near the space shuttle. An argument for a plasma density enhancement of the order of 10% very close to the shuttle, due to kinematic effects (corresponding to pileup of plasma) and not to plasma creation, is also presented. This kinetmatic density enhancement is insufficient, by an order of magnitude, to explain the plasma density enhancements inferred from Spacelab 2 data.

  8. Measurement of the beam longitudinal profile in a storage ring bynon-linear laser mixing

    SciTech Connect

    Beche, J.-F.; Byrd, J.; De Santis, S.; Denes, P.; Placidi, M.; Turner, W.; Zolotorev, M.

    2004-05-03

    We report on the development of a new technique for the measurement of the longitudinal beam profile in storage rings. This technique, which has been successfully demonstrated at the Advanced Light Source, mixes the synchrotron radiation with the light from a mode-locked solid state laser oscillator in a non-linear crystal. The up-converted radiation is then detected with a photomultiplier and processed to extract, store, and display the required information. The available choices of laser repetition frequency, pulse width, and phase modulation give a wide range of options for matching the bunch configuration of a particular storage ring. Besides the dynamic measurement of the longitudinal profile of each bunch, the instrument can monitor the evolution of the bunch tails, the presence of untrapped particles and their diffusion into nominally empty RF buckets (''ghostbunches'').

  9. Size modulated transition in the fluid-structure interaction losses in nano mechanical beam resonators

    NASA Astrophysics Data System (ADS)

    Vishwakarma, S. D.; Pandey, A. K.; Parpia, J. M.; Verbridge, S. S.; Craighead, H. G.; Pratap, R.

    2016-05-01

    An understanding of the dominant dissipative mechanisms is crucial for the design of a high-Q doubly clamped nanobeam resonator to be operated in air. We focus on quantifying analytically the viscous losses—the squeeze film damping and drag force damping—that limit the net quality factor of a beam resonator, vibrating in its flexural fundamental mode with the surrounding fluid as air at atmospheric pressure. Specifically, drag force damping dominates at smaller beam widths and squeeze film losses dominate at larger beam widths, with no significant contribution from structural losses and acoustic radiation losses. The combined viscous losses agree well with the experimentally measured Q of the resonator over a large range of beam widths, within the limits of thin beam theory. We propose an empirical relation between the maximum quality factor and the ratio of maximum beam width to the squeeze film air gap thickness.

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

    SciTech Connect

    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. Fail-safe ion chamber beam loss monitor system for personnel protection

    NASA Astrophysics Data System (ADS)

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

    1999-01-01

    A fail-safe beam loss monitor system has been designed for use in the Los Alamos Neutron Scattering Center (LANSCE) Radiation Security System (RSS). The latest version (Model III) has been in use since 1991. This system has been carefully designed to protect personnel from large radiation doses caused by errant beam conditions during beam transport. Due to limited shielding between the beam transport lines and occupied areas, personnel can safely occupy these areas only if the beam losses in the transport lines are sufficiently low. Although the usual solution is to increase the bulk shielding between the beam lines and the occupied areas, the physical dimensions of the site do not permit additional shielding to be added. In this paper we will discuss the design and implementation of the fail-safe beam loss monitor system.

  12. "DIAGNOSTIC" PULSE FOR SINGLE-PARTICLE-LIKE BEAM POSITION MEASUREMENTS DURING ACCUMULATION/PRODUCTION MODE IN THE LOS ALAMOS PROTON STORAGE RING

    SciTech Connect

    Kolski, Jeffrey S.; Baily, Scott A.; Bjorklund, Eric A.; Bolme, Gerald O.; Hall, Michael J.; Kwon, Sung I.; Martinez, Martin P.; Prokop, Mark S.; Shelley, Fred E. Jr.; Torrez, Phillip A.

    2012-05-14

    Beam position monitors (BPMs) are the primary diagnostic in the Los Alamos Proton Storage Ring (PSR). When injecting one turn, the transversemotion is approximated as a single particle with initial betatron position and angle {rvec x}{sub 0} and {rvec x}'{sub 0}. With single-turn injection, we fit the betatron tune, closed orbit (CO), and injection offset ({rvec x}{sub 0} and {rvec x}'{sub 0} at the injection point) to the turn-by-turn beam position. In production mode, we accumulate multiple turns, the transverse phase space fills after 5 injections (horizontal and vertical fractional betatron tunes {approx}0.2) resulting in no coherent betatron motion, and only the CO may be measured. The injection offset, which determines the accumulated beam size and is very sensitive to steering upstream of the ring, is not measurable in production mode. We describe our approach and ongoing efforts to measure the injection offset during production mode by injecting a 'diagnostic' pulse {approx}50 {micro}s after the accumulated beam is extracted. We also study the effects of increasing the linac RF gate length to accommodate the diagnostic pulse on the production beam position, transverse size, and loss.

  13. A Main Ring bunch length monitor by detecting two frequency components of the beam

    SciTech Connect

    Ieiri, T.; Jackson, G.

    1989-06-02

    The bunch length is measured by detecting two revolution frequency harmonics of the beam and taking the ratio of their amplitudes. Two heterodyne receivers have been made to direct them, one at 53MHz and the other at 159MHz. These signals are picked-up by a stripline detector. An analog circuit provides a signal proportional to the bunch length. The monitor measures variation of the bunch length as a function of time in the Main Ring. The measured signal, which sometimes shows that the bunches are tumbling in phase space, can be damped by feedback to the RF amplitude modulator. 9 refs., 12 figs., 1 tab.

  14. Simulation of crystalline beams in storage rings using molecular dynamics technique

    NASA Astrophysics Data System (ADS)

    Meshkov, I.; Katayama, T.; Sidorin, A.; Smirnov, A.; Syresin, E.; Trubnikov, G.; Tsutsui, H.

    2006-03-01

    Achieving very low temperatures in the beam rest frame can present new possibilities in accelerator physics. Increasing luminosity in the collider and in experiments with targets is a very important asset for investigating rare radioactive isotopes. The ordered state of circulating ion beams was observed at several storage rings: NAP-M [Budker, et al., in: Proceedings of the 4th All-Union Conference on Charged-Particle Accelerators [in Russian], vol. 2, Nauka, Moscow, 1975, p. 309; Budker et al., Part. Accel. 7 (1976) 197; Budker et al., At. Energ. 40 (1976) 49. E. Dementev, N. Dykansky, A. Medvedko et al., Prep. CERN/PS/AA 79-41, Geneva, 1979] (Novosibirsk), ESR [M. Steck et al., Phys. Rev. Lett. 77 (1996) 3803] and SIS [Hasse and Steck, Ordered ion beams, in: Proceeding of EPAC '2000] (Darmstadt), CRYRING [Danared et al., Observation of ordered ion beams in CRYRING, in: Proceeding of PAC '2001] (Stockholm) and PALLAS [Schramm et al., in: J.L. Duggan (Eds.), Proceedings of the Conference on Appl. of Acc. in Research and Industry AIP Conference Proceedings, p. 576 (to be published)] (Munich). In this report, the simulation of 1D crystalline beams with BETACOOL code is presented. The sudden reduction of momentum spread in the ESR experiment is described with this code. Simulation shows good agreement with experimental results and also with the intrabeam scattering (IBS) theory [Martini, Intrabeam scattering in the ACOOL-AA machines, CERN PS/84-9 AA, Geneva, 1984]. The code was used to calculate characteristics of the ordered state of ion beams for the TARN-II [Katayama, TARN II project, in: Proceedings of the IUCF workshop on nuclear physics with stored cooled beams, Spencer, IN, USA, 1984].

  15. Issues and experience with controlling beam loss at the Tevatron collider

    SciTech Connect

    Annala, Gerald; /Fermilab

    2007-07-01

    Controlling beam loss in the Tevatron collider is of great importance because of the delicate nature of the cryogenic magnet system and the collider detectors. Maximizing the physics potential requires optimized performance as well as protection of all equipment. The operating history of the Tevatron has significantly influenced the way losses are managed. The development of beam loss management in the Tevatron will be presented.

  16. Vertical split-ring resonator based anomalous beam steering with high extinction ratio

    PubMed Central

    Hsu, Wei-Lun; Wu, Pin Chieh; Chen, Jia-Wern; Chen, Ting-Yu; Cheng, Bo Han; Chen, Wei Ting; Huang, Yao-Wei; Liao, Chun Yen; Sun, Greg; Tsai, Din Ping

    2015-01-01

    Metasurfaces created artificially with metal nanostructures that are patterned on surfaces of different media have shown to possess “unusual” abilities to manipulate light. Limited by nanofabrication difficulties, so far most reported works have been based on 2D metal structures. We have recently developed an advanced e-beam process that allowed for the deposition of 3D nanostructures, namely vertical split-ring resonators (VSRRs), which opens up another degree of freedom in the metasurface design. Here we explore the functionality of beam steering with phase modulation by tuning only the vertical dimension of the VSRRs and show that anomalous steering reflection of a wide range of angles can be accomplished with high extinction ratio using the finite-difference-time-domain simulation. We also demonstrate that metasurfaces made of 3D VSRRs can be made with roughly half of the footprint compared to that of 2D nano-rods, enabling high density integration of metal nanostructures. PMID:26054048

  17. Modeling and Simulation of the Longitudinal Beam Dynamics - RF Station Interaction in the LHC Rings

    SciTech Connect

    Mastorides, T; Rivetta, C.; Fox, J.D.; Winkle, D.Van; Baudrenghien, P.; Tuckmantel, J.; /CERN

    2008-07-07

    A non-linear time-domain simulation has been developed to study the interaction between longitudinal beam dynamics and RF stations in the LHC rings. The motivation for this tool is to determine optimal LLRF configurations, to study system sensitivity on various parameters, and to define the operational and technology limits. It will be also used to study the effect of RF station noise, impedance, and perturbations on the beam life time and longitudinal emittance. It allows the study of alternative LLRF implementations and control algorithms. The insight and experience gained from our PEP-II simulation is important for this work. In this paper we discuss properties of the simulation tool that will be helpful in analyzing the LHC RF system and its initial results. Partial verification of the model with data taken during the LHC RF station commissioning is presented.

  18. Photodissociation of an Internally Cold Beam of CH+ Ions in a Cryogenic Storage Ring

    NASA Astrophysics Data System (ADS)

    O'Connor, A. P.; Becker, A.; Blaum, K.; Breitenfeldt, C.; George, S.; Göck, J.; Grieser, M.; Grussie, F.; Guerin, E. A.; von Hahn, R.; Hechtfischer, U.; Herwig, P.; Karthein, J.; Krantz, C.; Kreckel, H.; Lohmann, S.; Meyer, C.; Mishra, P. M.; Novotný, O.; Repnow, R.; Saurabh, S.; Schwalm, D.; Spruck, K.; Sunil Kumar, S.; Vogel, S.; Wolf, A.

    2016-03-01

    We have studied the photodissociation of CH+ in the Cryogenic Storage Ring at ambient temperatures below 10 K. Owing to the extremely high vacuum of the cryogenic environment, we were able to store CH+ beams with a kinetic energy of ˜60 keV for several minutes. Using a pulsed laser, we observed Feshbach-type near-threshold photodissociation resonances for the rotational levels J =0 - 2 of CH+, exclusively. In comparison to updated, state-of-the-art calculations, we find excellent agreement in the relative intensities of the resonances for a given J , and we can extract time-dependent level populations. Thus, we can monitor the spontaneous relaxation of CH+ to its lowest rotational states and demonstrate the preparation of an internally cold beam of molecular ions.

  19. Photodissociation of an Internally Cold Beam of CH^{+} Ions in a Cryogenic Storage Ring.

    PubMed

    O'Connor, A P; Becker, A; Blaum, K; Breitenfeldt, C; George, S; Göck, J; Grieser, M; Grussie, F; Guerin, E A; von Hahn, R; Hechtfischer, U; Herwig, P; Karthein, J; Krantz, C; Kreckel, H; Lohmann, S; Meyer, C; Mishra, P M; Novotný, O; Repnow, R; Saurabh, S; Schwalm, D; Spruck, K; Sunil Kumar, S; Vogel, S; Wolf, A

    2016-03-18

    We have studied the photodissociation of CH^{+} in the Cryogenic Storage Ring at ambient temperatures below 10 K. Owing to the extremely high vacuum of the cryogenic environment, we were able to store CH^{+} beams with a kinetic energy of ∼60  keV for several minutes. Using a pulsed laser, we observed Feshbach-type near-threshold photodissociation resonances for the rotational levels J=0-2 of CH^{+}, exclusively. In comparison to updated, state-of-the-art calculations, we find excellent agreement in the relative intensities of the resonances for a given J, and we can extract time-dependent level populations. Thus, we can monitor the spontaneous relaxation of CH^{+} to its lowest rotational states and demonstrate the preparation of an internally cold beam of molecular ions. PMID:27035300

  20. Scientific potential and design considerations for an undulator beam line on Aladdin storage ring

    SciTech Connect

    Arko, A. J.; Bader, S. D.; Dehmer, Joseph L.; Kim, S. H.; Knapp, G. S.; Shenoy, G. K.; Veal, B. W.; Young, C. E.; Brown, F. C.; Weaver, J. W.

    1985-04-08

    The unique features of undulator radiation, i.e., high photon flux and brightness, partial coherence, small beam divergence, spectral tunability, etc., mandate that undulators be included in the future plans for Aladdin. This will make it possible to perform the next generation of experiments in photon-stimulated spectroscopies. A team of scientists (see Appendix) has now been assembled to build an insertion device (ID) and the associated beam line at Aladdin. In considering the specifications for the ID, it was assumed that the ID beamline will be an SRC user facility. Consequently, design parameters were chosen with the intent of maximizing experimental flexibility consistent with a conservative design approach. A tunable ''clamshell'' undulator device was Chosen with a first harmonic tunable from 35 to 110 eV to operate on a 1 GeV storage ring. Higher harmonics will be utilized for experiments needing higher photon energies.

  1. Parametric Modeling of Electron Beam Loss in Synchrotron Light Sources

    SciTech Connect

    Sayyar-Rodsari, B.; Schweiger, C.; Hartman, E.; Corbett, J.; Lee, M.; Lui, P.; Paterson, E.; /SLAC

    2007-11-28

    Synchrotron light is used for a wide variety of scientific disciplines ranging from physical chemistry to molecular biology and industrial applications. As the electron beam circulates, random single-particle collisional processes lead to decay of the beam current in time. We report a simulation study in which a combined neural network (NN) and first-principles (FP) model is used to capture the decay in beam current due to Touschek, Bremsstrahlung, and Coulomb effects. The FP block in the combined model is a parametric description of the beam current decay where model parameters vary as a function of beam operating conditions (e.g. vertical scraper position, RF voltage, number of the bunches, and total beam current). The NN block provides the parameters of the FP model and is trained (through constrained nonlinear optimization) to capture the variation in model parameters as operating condition of the beam changes. Simulation results will be presented to demonstrate that the proposed combined framework accurately models beam decay as well as variation to model parameters without direct access to parameter values in the model.

  2. Two-channel method for measuring losses in a ring optical resonator at a wavelength of 632.8 nm

    NASA Astrophysics Data System (ADS)

    Azarova, V. V.; Bessonov, A. S.; Bondarev, A. L.; Makeev, A. P.; Petrukhin, E. A.

    2016-07-01

    A two-channel method is proposed for measuring losses in an optical ring resonator (RR), in which eigenmodes (counterpropagating waves) are excited by means of a Zeeman ring He – Ne laser with a wavelength of 632.8 nm. The measured frequency splitting of the laser counterpropgating waves is used to determine the absolute value of losses in an exemplary RR. The value of losses in the measured RR is determined by comparing the resonance width of the output radiation intensity with the resonance width of the radiation intensity for an exemplary resonator. The algorithm of intensity resonance processing takes into account the distortions caused by the dynamic effect, which allows a significant increase in the accuracy (up to 1% – 2%) and sensitivity of the proposed method. The measured losses in the RR with a perimeter of 28 cm constitute 80 – 5000 ppm.

  3. Beam loss studies in high-intensity heavy-ion linacs

    NASA Astrophysics Data System (ADS)

    Ostroumov, P. N.; Aseev, V. N.; Mustapha, B.

    2004-09-01

    The proposed Rare Isotope Accelerator (RIA) Facility, an innovative exotic-beam facility for the production of high-quality beams of short-lived isotopes, consists of a fully superconducting 1.4GV driver linac and a 140MV postaccelerator. To produce sufficient intensities of secondary beams the driver linac will provide 400kW primary beams of any ion from hydrogen to uranium. Because of the high intensity of the primary beams the beam losses must be minimized to avoid radioactivation of the accelerator equipment. To keep the power deposited by the particles lost on the accelerator structures below 1 W/m, the relative beam losses per unit length should be less than 10-5, especially along the high-energy section of the linac. A new beam dynamics simulation code TRACK has been developed and used for beam loss studies in the RIA driver linac. In the TRACK code, ions are tracked through the three-dimensional electromagnetic fields of every element of the linac starting from the electron cyclotron resonance (ECR) ion source to the production target. The simulation starts with a multicomponent dc ion beam extracted from the ECR. The space charge forces are included in the simulations. They are especially important in the front end of the driver linac. Beam losses are studied by tracking a large number of particles (up to 106) through the whole linac considering all sources of error such us element misalignments, rf field errors, and stripper thickness fluctuations. For each configuration of the linac, multiple sets of error values have been randomly generated and used in the calculations. The results are then combined to calculate important beam parameters, estimate beam losses, and characterize the corresponding linac configuration. To track a large number of particles for a comprehensive number of error sets (up to 500), the code TRACK was parallelized and run on the Jazz computer cluster at ANL.

  4. Beam loss scenarios and strategies for machine protection at the LHC

    NASA Astrophysics Data System (ADS)

    Schmidt, R.; Assmann, R.; Burkhardt, H.; Carlier, E.; Dehning, B.; Goddard, B.; Jeanneret, J. B.; Kain, V.; Puccio, B.; Wenninger, J.

    2003-12-01

    At the Large Hadron Collider (LHC) with nominal parameters at 7 TeV, each proton beam has an energy of more than 330 MJ threatening to damage accelerator equipment in case of uncontrolled beam loss. To prevent such damage, kickers are fired in case of failure deflecting the beams into dump blocks. The dump blocks are the only elements that can safely absorb the beams without damage. The time constant for particle losses depends on the specific failure and ranges from microseconds to several seconds. Starting with some typical failure scenarios, the strategy for the protection during LHC beam operation is illustrated. The systems designed to ensure safe operation, such as beam dump, beam instruments, collimators / absorbers and interlocks are discussed.

  5. First atomic physics experiments with cooled stored ion beams at the Heidelberg heavy-ion ring TSR

    SciTech Connect

    Wolf, A.; Balykin, V.; Baumann, W.; Berger, J.; Bisoffi, G.; Blatt, P.; Blum, M.; Faulstich, A.; Friedrich, A.; Gerhard, M.; Geyer, C.; Grieser, M.; Grieser, R.; Habs, D.; Heyng, H.W.; Hochadel, B.; Holzer, B.; Huber, G.; Jaeschke, E.; Jung, M.; Karafillidis, A.; Kilgus, G.; Klein, R.; Kraemer, D.; Krause, P.; Krieg, M.; Kuehl, T.; Matl, K.; Mueller, A.; Music, M.; Neumann, R.; Neureither, G.; Ott, W.; Petrich, W.; Povh, B.; Repnow, R.; Schroeder, S.; Schuch, R.; Schwalm, D.; Sigray, P.; Steck, M.; Stokstad, R.; Szmola, E.; Wagner, M.; Wanner, B.; Welti, K.; Zwickler, S. Max-Planck-Institut fuer Kernphysik, Heidelberg Manne Siegbahn Institute , Stockholm Institut fuer Kernphysik, Universitaet Giessen, Institut fuer Physik, Universitaet Mainz Gesellschaft fuer Schwerionenforschung , Darmstadt (Fed

    1990-06-01

    An overview of atomic physics experiments at the heavy ion Test Storage Ring (TSR) is given. Highly charged ions up to fully stripped silicon have been stored at energies between 4 and 12 MeV/u. The enhancement of the beam intensity by stacking, the beam lifetime, and electron cooling of these ion beams are discussed. Radiative and state-selective dielectronic recombination rates of hydrogen-like oxygen ions with free electrons from the electron cooler were measured. Beam noise spectra are being investigated with regard to collective effects caused by the Coulomb interaction in the cold ion beams. Resonance fluorescence from stored single-charged ions was observed using tunable narrow-band lasers. First indications of laser cooling in a storage ring were seen.

  6. Annular spherically focused ring transducers for improved single-beam acoustical tweezers

    NASA Astrophysics Data System (ADS)

    Mitri, F. G.

    2016-02-01

    The use of ultrasonic transducers with a central hollow is suggested for improved single-beam acoustical tweezers applications. Within the framework of the Fresnel-Kirchhoff parabolic approximation, a closed-form partial-wave series expansion (PWSE) for the incident velocity potential (or pressure) field is derived for an annular spherically focused ring (asfr) with uniform vibration across its surface in spherical coordinates. The Rayleigh-Sommerfeld diffraction integral and the addition theorems for the Legendre and spherical wave functions are used to obtain the PWSE assuming a weakly focused beam (with a focusing angle α ≤ 20°). The PWSE allows evaluating the incident field from the finite asfr in 3D. Moreover, the obtained solution allows computing efficiently the acoustic scattering and radiation force on a sphere centered on the beam's axis of wave propagation. The analytical solution is valid for wavelengths largely exceeding the radius of the asfr and when the viscosity of the surrounding fluid can be neglected. Numerical predictions for the beam-forming, scattering, and axial time-averaged radiation force are performed with particular emphasis on the asfr thickness, the axial distance separating the sphere from the center of the transducer, the (non-dimensional) size of the transducer, as well as the sphere's elastic properties without restriction to the long- (i.e., Rayleigh) or the short-wavelength (i.e., ray acoustics) regimes. Potential applications of the present solution are in beam-forming design, particle tweezing, and manipulation due to negative forces using ultrasonic asfr transducers.

  7. Design of Injection and Extraction at an 8-GeV Booster Ring and the J-PARC Main Ring for Multi-MW Output Beam Power

    NASA Astrophysics Data System (ADS)

    Harada, Hiroyuki; Hotchi, Hideaki; Igarashi, Susumu; Sato, Yoichi; Koseki, Tadashi

    The 240-kW output beam power in the MR has been achieved for a 30-GeV user operation with the repetition cycle of 2.48 sec and injecting proton beams of 380-kW equivalent intensity from RCS. The MR aims to realize 750-kW beam operation with faster repetition cycle of ˜1 s and injecting proton beams of 600-kW equivalent intensity from RCS. The MR is developing the new type power supplies of MR main magnets and high-impedance core of MR RF cavities toward faster repetition cycle. We are now exploring the further beam power upgrade scenario of the J-PARC accelerators. As one possible scenario toward a multi-MW output beam power from MR, a new 8-GeV booster ring (BR) between RCS and MR is also designed. The injection energy of the MR increases from present 3-GeV to 8-GeV. The higher injection energy of the MR would be able to mitigate a space charge force in MR injection energy region and secure the acceptance clearance of beam from MR physical aperture. In this paper, the designed injection and extraction system of BR are described. Additionally, a new concept of BR extraction and MR injection toward multi-MW output beam power are described.

  8. Three-dimensional ordering of cold ion beams in a storage ring: A molecular-dynamics simulation study

    SciTech Connect

    Yuri, Yosuke

    2015-06-29

    Three-dimensional (3D) ordering of a charged-particle beams circulating in a storage ring is systematically studied with a molecular-dynamics simulation code. An ion beam can exhibit a 3D ordered configuration at ultralow temperature as a result of powerful 3D laser cooling. Various unique characteristics of the ordered beams, different from those of crystalline beams, are revealed in detail, such as the single-particle motion in the transverse and longitudinal directions, and the dependence of the tune depression and the Coulomb coupling constant on the operating points.

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

    NASA Astrophysics Data System (ADS)

    Barranco García, Javier; Gilardoni, Simone

    2011-03-01

    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 better shielding. New simulations demonstrate the satisfactory performance of the new extraction optics and its suitability to be implemented in the machine. Finally, beam loss measurements in these new operation conditions confirmed the previous simulation results.

  10. Development of an inner profile measurement instrument using a ring beam device

    NASA Astrophysics Data System (ADS)

    Yoshizawa, T.; Wakayama, T.

    2010-11-01

    Inner profile measurement is an important matter in such fields as medicine, dentistry and anthropology as well as mechanical engineering and other industrial applications. Here we describe recent development of our measurement principle for inner diameter of pipes and/or holes. The key device in this technique is a ring beam device which consists of a conical mirror and a laser diode. And the fundamental principle is based on optical sectioning without using any contact type stylus. The optically sectioned profile of an inner wall of a pipe-like object is analyzed to give the inner profile in addition to the inner diameter. This optical instrument with a simple and small configuration is now under development for practical uses. In our hitherto trial experimental works, the availability of this instrument has been evaluated in many cases and availability for practical applications is expected, especially, for measurement and inspection of mechanical components and elements besides pipes. This ring beam device consisting of a conical mirror and a LD is assembled to form a disk-like light sheet. We show measurement result of pipes and holes, and, at the same time, report a compact inner profile measuring instrument at this point. Both the ring beam device and a miniaturized CCD camera are fabricated into a glass tube. Availability of this instrument is shown by measuring the inner profiles of various pipes. In response to this trial, there appeared a strong request that not only the internal but external profiles should be measured simultaneously. Therefore we propose potentially possible method for measurement of external profile at the same time with internal profile. If one pair of concave mirrors are used in our arrangement, external profile is captured. In combination with inner profile measurement technique, simultaneous measurement of inner and outer profiles becomes attainable. A measurement result on a bevel gear shows availability of here proposed

  11. RESULTS OF BACKGROUND SUBTRACTION TECHNIQUES ON THE SPALLATION NEUTRON SOURCE BEAM LOSS MONITORS

    SciTech Connect

    Pogge, James R; Zhukov, Alexander P

    2010-01-01

    Recent improvements to the Spallation Neutron Source (SNS) beam loss monitor (BLM) designs have been made with the goal of significantly reducing background noise. This paper outlines this effort and analyzes the results. The significance of this noise reduction is the ability to use the BLM sensors [1], [2], [3] distributed throughout the SNS accelerator as a method to monitor activation of components as well as monitor beam losses.

  12. Electron beam guiding by grooved SiO2 parallel plates without energy loss

    NASA Astrophysics Data System (ADS)

    Xue, Yingli; Yu, Deyang; Liu, Junliang; Zhang, Mingwu; Yang, Bian; Zhang, Yuezhao; Cai, Xiaohong

    2015-12-01

    Using a pair of grooved SiO2 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.

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

    SciTech Connect

    Xue, Yingli; Yu, Deyang Liu, Junliang; Zhang, Mingwu; Yang, Bian; Zhang, Yuezhao; Cai, Xiaohong

    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.

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

    SciTech Connect

    WITKOVER,R.; GASSNER,D.

    2002-05-06

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

  15. Beam loss and backgrounds in the CDF and D0 detectors due to nuclear elastic beam-gas scattering

    SciTech Connect

    Alexandr I. Drozhdin; Valery A. Lebedev; Nikolai V. Mokhov

    2003-05-27

    Detailed simulations were performed on beam loss rates in the vicinity of the Tevatron Collider detectors due to beam-gas nuclear elastic interactions. It turns out that this component can drive the accelerator-related background rates in the CDF and D0 detectors, exceeding those due to outscattering from collimation system, inelastic beam-gas interactions and other processes [1, 2]. Results of realistic simulations with the STRUCT and MARS codes are presented for the interaction region components and the CDF and D0 detectors. It is shown that a steel mask placed upstream of the detectors can reduce the background rates by almost an order of magnitude.

  16. Tight focusing of a double-ring-shaped, azimuthally polarized beam through a dielectric interface.

    PubMed

    Shu, Jianhua; Chen, Ziyang; Pu, Jixiong; Liu, Yongxin

    2014-06-01

    We investigate the tight focusing properties of a double-ring-shaped, azimuthally polarized vector beam (DRS-APVB) by use of vectorial Debye theory. It is shown that a dark channel with an ultralong depth of focus (~106λ) and subwavelength focal holes (~0.5λ) can be generated by focusing a DRS-APVB through a dielectric interface with an annular high-numerical aperture (NA) objective lens. The influence of the NA of the objective, the relative refractive indices of two dielectric media, and the probe depth of the system on the focusing properties of the dark channel has been studied in detail. Such a non-diffracting dark channel could find potential applications in atom optical experiments, such as with atomic lenses, atom traps, and atom switches. PMID:24977354

  17. Generating Ultrashort Coherent Soft X-ray Radiation in Storage Rings Using Angular-modulated Electron Beams

    SciTech Connect

    Xiang, D.; Wan, W.; /LBL, Berkeley

    2010-08-23

    A technique is proposed to generate ultrashort coherent soft x-ray radiation in storage rings using angular-modulated electron beams. In the scheme a laser operating in the TEM01 mode is first used to modulate the angular distribution of the electron beam in an undulator. After passing through a special beam line with non-zero transfer matrix element R{sub 54}, the angular modulation is converted to density modulation which contains considerable higher harmonic contents of the laser. It is found that the harmonic number can be one or two orders of magnitude higher than the standard coherent harmonic generation method which relies on beam energy modulation. The technique has the potential of generating femtosecond coherent soft x-ray radiation directly from an infrared seed laser and may open new research opportunities for ultrafast sciences in storage rings.

  18. Direct focusing error correction with ring-wide TBT beam position data

    SciTech Connect

    Yang, M.J.; /Fermilab

    2011-03-01

    Turn-By-Turn (TBT) betatron oscillation data is a very powerful tool in studying machine optics. Hundreds and thousands of turns of free oscillations are taken in just few tens of milliseconds. With beam covering all positions and angles at every location TBT data can be used to diagnose focusing errors almost instantly. This paper describes a new approach that observes focusing error collectively over all available TBT data to find the optimized quadrupole strength, one location at a time. Example will be shown and other issues will be discussed. The procedure presented clearly has helped to reduce overall deviations significantly, with relative ease. Sextupoles, being a permanent feature of the ring, will need to be incorporated into the model. While cumulative effect from all sextupoles around the ring may be negligible on turn-to-turn basis it is not so in this transfer line analysis. It should be noted that this procedure is not limited to looking for quadrupole errors. By modifying the target of minimization it could in principle be used to look for skew quadrupole errors and sextupole errors as well.

  19. Fairy Ring Disease of Cranberry: Assessment of Crop Losses and Impact on Cultivar Genotype

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fairy ring is a disease of cultivated cranberries common in the eastern growing regions of the U.S., especially New Jersey and Massachusetts. Rings may persist for many years and current recommendations are costly and largely ineffective. The goal of this study was to accurately assess the impact of...

  20. Behavioral responses to tooth loss in wild ring-tailed lemurs (Lemur catta) at the Beza Mahafaly Special Reserve, Madagascar.

    PubMed

    Millette, James B; Sauther, Michelle L; Cuozzo, Frank P

    2009-09-01

    Severe dental wear and tooth loss is often assumed to impede the processing, breakdown, and energetic conversion of food items, thereby negatively impacting individual health, reproduction, and survival. Ring-tailed lemurs at the Beza Mahafaly Special Reserve demonstrate exceptionally high frequencies of severe dental wear and antemortem tooth loss, yet often survive multiple years with these impairments. To test the hypothesis that these lemurs mitigate tooth loss through behavioral adjustments, we collected 191 h of observational data from 16 focal subjects, eight without tooth loss and eight with between 3% and 44% loss. These data indicate dentally-impaired ring-tailed lemurs show compensatory behaviors consistent with the demands of living in a social group. During early afternoon (12:00-14:30 h) individuals with loss showed trends towards higher frequencies of foraging and grooming, while individuals without loss rested significantly more often. Individuals with >10% loss (n = 7) showed higher frequencies of feeding, foraging, and grooming, and lower frequencies of resting during this period than individuals with <10% loss (n = 9). Individuals with tooth loss maintained relatively higher levels of feeding and foraging throughout the day. These individuals licked tamarind fruit at higher frequencies, likely spending more time softening it before ingestion. These individuals did not demonstrate longer feeding bouts overall, although bouts involving tamarinds were significantly longer. Individuals with marked toothcomb wear engaged in higher rates of certain types of allogrooming, demonstrating that social behaviors are used to compensate for reduced grooming efficiency. These data have implications for interpreting behavioral responses to dental impairment in the fossil record. PMID:19373842

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

    SciTech Connect

    Wangler, T.P.; Gray, E.R.; Krawczyk, F.L.; Kurennoy, S.S.; Lawrence, G.P.; Ryne, R.D.; Crandall, K.R.

    1998-12-31

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

  2. H- Beam Loss and Evidence for Intrabeam Stripping in the LANSCE Linac

    SciTech Connect

    Rybarcyk, Lawrence J.; Kelsey, Charles T. IV; McCrady, Rodney C.; Pang, Xiaoying

    2012-05-15

    The LANSCE accelerator complex is a multi-beam, multi-user facility that provides high-intensity H{sup +} and H{sup -} particle beams for a variety of user programs. At the heart of the facility is a room temperature linac that is comprised of 100-MeV drift tube and 800-MeV coupled cavity linac (CCL) structures. Although both beams are similar in intensity and emittance at 100 MeV, the beam-loss monitors along the CCL show a trend of increased loss for H{sup -} that is not present for H{sup +}. This difference is attributed to stripping mechanisms that affect H{sup -} and not H{sup +}. We present the results of an analysis of H{sup -} beam loss along the CCL that incorporates beam spill measurements, beam dynamics simulations, analytical models and radiation transport estimates using the MCNPX code. The results indicate a significant fraction of these additional losses result from intrabeam stripping.

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

    SciTech Connect

    Guaglio, G.; Dehning, B.; Santoni, C.

    2005-06-08

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

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

    SciTech Connect

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

    2011-11-01

    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.

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

    SciTech Connect

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

    2012-07-11

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

  6. ACCELERATOR PHYSICS MODEL OF EXPECTED BEAM LOSS ALONG THE SNS ACCELERATOR FACILITY DURING NORMAL OPERATION.

    SciTech Connect

    CATALAN - LASHERAS,N.; COUSINEAU,S.; GALAMBOS,J.; HOLTKAMP,N.; RAPARIA,D.; SHAFER,R.; STAPLES,J.; STOVALL,J.; TANKE,E.; WANGLER,T.; WEI,J.

    2002-06-03

    The most demanding requirement in the design of the SNS accelerator chain is to keep the accelerator complex under hands-on maintenance. This requirement implies a hard limit for residual radiation below 100 mrem/hr at one feet from the vacuum pipe and four hours after shutdown for hundred days of normal operation. It has been shown by measurements as well as simulation [l] that this limit corresponds to 1-2 Watts/meter average beam losses. This loss level is achievable all around the machine except in specific areas where remote handling will be necessary. These areas have been identified and correspond to collimation sections and dumps where a larger amount of controlled beam loss is foreseen. Even if the average level of loss is kept under 1 W/m, there are circumstances under which transient losses occur in the machine. The prompt radiation or potential damage in the accelerator components can not be deduced from an average beam loss of 1 W/m. At the same time, controlled loss areas require a dedicated study to clarify the magnitude and distribution of the beam loss. From the front end to the target, we have estimated the most probable locations for transient losses and given an estimate of their magnitude and frequency. This information is essential to calculate the necessary shielding or determine the safety procedures during machine operation. Losses in controlled areas, and the cleaning systems are the subject of Section 2. The inefficiency of each system will be taken into account for the discussion on Section 3 where n controlled loss is estimated. Section 4 summarizes our findings and presents a global view of the losses along the accelerator chain.

  7. Location of Maximum Credible Beam Losses in LCLS Injector

    SciTech Connect

    Mao, Stan

    2010-12-13

    The memo describes the maximum credible beam the LCLS injector can produce and lose at various locations along the beamline. The estimation procedure is based upon three previous reports [1, 2, 3]. While specific numbers have been updated to accurately reflect the present design parameters, the conclusions are very similar to those given in Ref 1. The source of the maximum credible beam results from the explosive electron emission from the photocathode if the drive laser intensity exceeds the threshold for plasma production. In this event, the gun's RF field can extract a large number of electrons from this plasma which are accelerated out of the gun and into the beamline. This electron emission persists until it has depleted the gun of all its energy. Hence the number of electrons emitted per pulse is limited by the amount of stored RF energy in the gun. It needs to be emphasized that this type of emission is highly undesirable, as it causes permanent damage to the cathode.

  8. The energy-dependent electron loss model for pencil beam dose kernels

    NASA Astrophysics Data System (ADS)

    Chvetsov, Alexei V.; Sandison, George A.; Yeboah, Collins

    2000-10-01

    The `monoenergetic' electron loss model was derived in a previous work to account for pathlength straggling in the Fermi-Eyges pencil beam problem. In this paper, we extend this model to account for energy-loss straggling and secondary knock-on electron transport in order to adequately predict a depth dose curve. To model energy-loss straggling, we use a weighted superposition of a discrete number of monoenergetic pencil beams with different initial energies where electrons travel along the depth-energy characteristics in the continuous slowing down approximation (CSDA). The energy straggling spectrum at depth determines the weighting assigned to each monoenergetic pencil beam. Supplemented by a simple transport model for the secondary knock-on electrons, the `energy-dependent' electron loss model predicts both lateral and depth dose distributions from the electron pencil beams in good agreement with Monte Carlo calculations and measurements. The calculation of dose distribution from a pencil beam takes 0.2 s on a Pentium III 500 MHz computer. Being computationally fast, the `energy-dependent' electron loss model can be used for the calculation of 3D energy deposition kernels in dose optimization schemes without using precalculated or measured data.

  9. The role of electronic energy loss in ion beam modification of materials

    DOE PAGESBeta

    Weber, William J.; Duffy, Dorothy M.; Thome, Lionel; Zhang, Yanwen

    2014-10-05

    The interaction of energetic ions with solids results in energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and electronic energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and electronic energy loss on ion beam modification of materials. The results demonstrate that nuclear and electronic energy loss can lead to additive effects on irradiation damage production in some materials; while inmore » other materials, the competitive effects of electronic energy loss leads to recovery of damage induced by elastic collision cascades. Lastly, these results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.« less

  10. The role of electronic energy loss in ion beam modification of materials

    SciTech Connect

    Weber, William J.; Duffy, Dorothy M.; Thome, Lionel; Zhang, Yanwen

    2014-10-05

    The interaction of energetic ions with solids results in energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and electronic energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and electronic energy loss on ion beam modification of materials. The results demonstrate that nuclear and electronic energy loss can lead to additive effects on irradiation damage production in some materials; while in other materials, the competitive effects of electronic energy loss leads to recovery of damage induced by elastic collision cascades. Lastly, these results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.

  11. First calibration of a Cherenkov beam loss sensor at ALICE using SiPM

    NASA Astrophysics Data System (ADS)

    Intermite, A.; Putignano, M.; Wolski, A.

    2012-06-01

    The need for real-time monitoring of beam losses, including evaluation of their intensity and localization of their exact position, together with the possibility to overcome the limitations due to the reduced space for the diagnostics, makes exploitation of the Cherenkov effect in optical fibres, one of the most suitable candidates for beam loss monitoring. In this article, we report on the first tests of an optical fibre beam loss monitor based on large numerical aperture pure silica fibres and silicon photomultipliers. The tests were carried out at the ALICE accelerator research and development facility, Daresbury Laboratories, UK. In contrast to the results already published where the fibres are longitudinally placed with respect to the accelerator beam path and the losses are multidirectional charged particle showers, for the first time a dedicated set-up with an incident accelerator beam impinging directly on the optical fibre was used for optimizing the collection efficiency of the Cherenkov effect as a function of the incident angle by changing the fibre direction. For this purpose large core fibres were used together with the latest generation silicon detector instead of the standard photomultiplier tubes commonly used for Cherenkov beam loss monitoring. The experiments described in this contribution aim to demonstrate the suitability of the optical fibre sensor for loss monitoring, to optimize the Collection Efficiency (CE) of the Cherenkov photons inside the fibre as a function of the particle incident angle, to calibrate the sensor and calculate its sensitivity, and to understand the limits of temporal resolution of losses from different bunches in the accelerator.

  12. SNS Ring Operational Experience and Power Ramp Up Status

    SciTech Connect

    Plum, Michael A

    2009-01-01

    The SNS Ring has now been operating for about 3.5 years, and our march continues to increase the beam power to the full design value of 1.4 MW. The Ring is a loss-limited machine, and in general the radioactivation levels are good, but there are some unanticipated hot spots that we are working to improve. High intensity collective effects such as space-charge and beam instability have had minimal impact on beam operations to date. The cross plane coupling issue in the ring to target beam transport line has been solved. We will also discuss the status of equipment upgrades in the high-energy beam transport beam line, the injection-dump beam transport line, the ring, and the ring-to-target beam transport line.

  13. Measured and simulated heavy-ion beam loss patterns at the CERN Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Hermes, P. D.; Bruce, R.; Jowett, J. M.; Redaelli, S.; Salvachua Ferrando, B.; Valentino, G.; Wollmann, D.

    2016-05-01

    The Large Hadron Collider (LHC) at CERN pushes forward to new regimes in terms of beam energy and intensity. In view of the combination of very energetic and intense beams together with sensitive machine components, in particular the superconducting magnets, the LHC is equipped with a collimation system to provide protection and intercept uncontrolled beam losses. Beam losses could cause a superconducting magnet to quench, or in the worst case, damage the hardware. The collimation system, which is optimized to provide a good protection with proton beams, has shown a cleaning efficiency with heavy-ion beams which is worse by up to two orders of magnitude. The reason for this reduced cleaning efficiency is the fragmentation of heavy-ion beams into isotopes with a different mass to charge ratios because of the interaction with the collimator material. In order to ensure sufficient collimation performance in future ion runs, a detailed theoretical understanding of ion collimation is needed. The simulation of heavy-ion collimation must include processes in which 82+208Pb ions fragment into dozens of new isotopes. The ions and their fragments must be tracked inside the magnetic lattice of the LHC to determine their loss positions. This paper gives an overview of physical processes important for the description of heavy-ion loss patterns. Loss maps simulated by means of the two tools ICOSIM [1,2] and the newly developed STIER (SixTrack with Ion-Equivalent Rigidities) are compared with experimental data measured during LHC operation. The comparison shows that the tool STIER is in better agreement.

  14. Blowup of a weak beam due to interaction with a strong beam in an electron storage ring

    SciTech Connect

    Kheifets, S.

    1983-07-01

    The theoretical description of the beam-beam interaction presented here takes into account all the important features of the beam-beam phenomenon: the nonlinear beam-beam force and its dependnce on both transverse coordinates, damping of the oscillations, presence of noise in the particle motion, in particular the quantum noise in its synchrotron radiation, actual machine functions, layout and the number B of interaction points, and to some extent imperfections present in the machine. The model deals not with a separate particle, but with the beam as a whole using phase space distribution functions and the average (unperturbed and perturbed) characteristics of the bunch.

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

    SciTech Connect

    Pace, D. C.; Heidbrink, W. W.; Muscatello, C. M.; Zhu, Y. B.; Fisher, R. K.; Van Zeeland, M. A.; Garcia-Munoz, M.; Darrow, D. S.; Nazikian, R.

    2010-10-15

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

  16. Simultaneous linear optics and coupling correction for storage rings with turn-by-turn beam position monitor data

    SciTech Connect

    Yang, Xi; Huang, Xiaobiao

    2015-11-10

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

  17. Loss of c-Cbl RING finger function results in high-intensity TCR signaling and thymic deletion

    PubMed Central

    Thien, Christine B F; Blystad, Frøydis D; Zhan, Yifan; Lew, Andrew M; Voigt, Valentina; Andoniou, Christopher E; Langdon, Wallace Y

    2005-01-01

    Signaling from the T-cell receptor (TCR) in thymocytes is negatively regulated by the RING finger-type ubiquitin ligase c-Cbl. To further investigate this regulation, we generated mice with a loss-of-function mutation in the c-Cbl RING finger domain. These mice exhibit complete thymic deletion by young adulthood, which is not caused by a developmental block, lack of progenitors or peripheral T-cell activation. Rather, this phenotype correlates with greatly increased expression of the CD5 and CD69 activation markers and increased sensitivity to anti-CD3-induced cell death. Thymic loss contrasts the normal fate of the c-Cbl−/− thymus, even though thymocytes from both mutant mice show equivalent enhancement in proximal TCR signaling, Erk activation and calcium mobilization. Remarkably, only the RING finger mutant thymocytes show prominent TCR-directed activation of Akt. We show that the mutant c-Cbl protein itself is essential for activating this pathway by recruiting the p85 regulatory subunit of PI 3-kinase. This study provides a unique model for analyzing high-intensity TCR signals that cause thymocyte deletion and highlights multiple roles of c-Cbl in regulating this process. PMID:16211006

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

    SciTech Connect

    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.

  19. Anomalous Beam-Ion Loss in TFTR Reversed Magnetic Shear Plasmas

    SciTech Connect

    Ruskov, E.; Bell, M.; Budny, R.V.; McCune, D.C.; Medley, S.S.; Redi, M.H.; Scott, S.; Synakowski, E.J.; von Goeler, S.; White, R.B.; Zweben, S.J.

    1999-02-01

    Anomalous beam-ion loss has been observed in an experiment with short tritium beam pulses injected into deuterium-beam-heated Tokamak Fusion Test Reactor plasmas (P{sub NBI}=15 thinspthinspMW) with reversed magnetic shear (RS). Comparisons of the measured total 14thinspthinspMeV neutron emission, the neutron flux along eight radial locations, and the perpendicular plasma stored energy with predictions from an extensive set of TRANSP simulations suggest that about 40{percent} beam power is lost on a time scale much shorter than the tritium beam pulse length {Delta}t=70 thinspthinspms. In contrast with recent results [K. Tobita {ital et al.,} Nucl.thinspthinspFusion {bold 37}, 1583 (1997)] from RS experiments at JT-60U, we were not able to show conclusively that magnetic field ripple is responsible for this anomaly. {copyright} {ital 1999} {ital The American Physical Society}

  20. Anomalous Beam-Ion Loss in TFTR Reversed Magnetic Shear Plasmas

    NASA Astrophysics Data System (ADS)

    Ruskov, E.; Bell, M.; Budny, R. V.; McCune, D. C.; Medley, S. S.; Redi, M. H.; Scott, S.; Synakowski, E. J.; von Goeler, S.; White, R. B.; Zweben, S. J.

    1999-02-01

    Anomalous beam-ion loss has been observed in an experiment with short tritium beam pulses injected into deuterium-beam-heated Tokamak Fusion Test Reactor plasmas ( PNBI = 15 MW) with reversed magnetic shear (RS). Comparisons of the measured total 14 MeV neutron emission, the neutron flux along eight radial locations, and the perpendicular plasma stored energy with predictions from an extensive set of TRANSP simulations suggest that about 40% beam power is lost on a time scale much shorter than the tritium beam pulse length Δt = 70 ms. In contrast with recent results [K. Tobita et al., Nucl. Fusion 37, 1583 (1997)] from RS experiments at JT-60U, we were not able to show conclusively that magnetic field ripple is responsible for this anomaly.

  1. Energy matching of 1. 2 GeV positron beam to the SLC (Stanford Linear Collider) damping ring

    SciTech Connect

    Clendenin, J.E.; Helm, R.H.; Jobe, R.K.; Kulikov, A.; Sheppard, J.C.

    1989-08-01

    Positrons collected at the SLC positron source are transported over a 2-km path at 220 MeV to be reinjected into the linac for acceleration to 1.2 GeV, the energy of the emittance damping ring. Since the positron bunch length is a significant fraction of a cycle of the linac-accelerating RF, the energy spread at 1.2 GeV is considerably larger than the acceptance of the linac-to-ring (LTR) transport system. Making use of the large pathlength difference at the beginning of the LTR due to this energy spread, a standard SLAC 3-m accelerating section has been installed in the LTR to match the longitudinal phase space of the positron beam to the acceptance of the damping ring. The design of the matching system is described, and a comparison of operating results within simulations is presented. 5 refs., 4 figs., 1 tab.

  2. Two-dimensional finite-element analyses of simulated rotor-fragment impacts against rings and beams compared with experiments

    NASA Technical Reports Server (NTRS)

    Stagliano, T. R.; Witmer, E. A.; Rodal, J. J. A.

    1979-01-01

    Finite element modeling alternatives as well as the utility and limitations of the two dimensional structural response computer code CIVM-JET 4B for predicting the transient, large deflection, elastic plastic, structural responses of two dimensional beam and/or ring structures which are subjected to rigid fragment impact were investigated. The applicability of the CIVM-JET 4B analysis and code for the prediction of steel containment ring response to impact by complex deformable fragments from a trihub burst of a T58 turbine rotor was studied. Dimensional analysis considerations were used in a parametric examination of data from engine rotor burst containment experiments and data from sphere beam impact experiments. The use of the CIVM-JET 4B computer code for making parametric structural response studies on both fragment-containment structure and fragment-deflector structure was illustrated. Modifications to the analysis/computation procedure were developed to alleviate restrictions.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  4. Modelling of Ion Bernstein Wave-Driven Deuterium Beam Ion Losses in TFTR.

    NASA Astrophysics Data System (ADS)

    Heeter, R. F.; Fisch, N. J.; Darrow, D. S.; Herrmann, M. C.; Majeski, R.

    1996-11-01

    A 1-D velocity-space diffusion/drag model is used to understand MeV-range deuterium beam ion losses driven by mode-converted Ion Bernstein Waves in TFTR. [D. Darrow et. al., this conference.] Simulated losses provide insight into the nature of the loss process and an estimation of the velocity diffusion coefficent. Implications for channeling of alpha particle energy to fuel ions are discussed. [Work supported by U.S. DoE contract DE-AC02-76-CH03073; two of the authors (RFH and MCH) also acknowledge the support of the Fannie and John Hertz Foundation.

  5. Observations of neutral beam and ICRF tail ion losses due to Alfven modes in TFTR

    SciTech Connect

    Darrow, D.S.; Zweben, S.J.; Chang, Z.

    1996-04-01

    Fast ion losses resulting from MHD modes at the Alfven frequency, such as the TAE, have been observed in TFTR. The modes have been driven both by neutral beam ions, at low B{sub T}, and by H-minority ICRF tail ions at higher B{sub T}. The measurements indicate that the loss rate varies linearly with the mode amplitude, and that the fast ion losses during the mode activity can be significant, e.g. up to 10% of the input power is lost in the worst case.

  6. Effects of a hybrid superconducting three-pole wiggler on the stored beam at the SAGA-LS storage ring

    NASA Astrophysics Data System (ADS)

    Koda, Shigeru; Iwasaki, Yoshitaka; Takabayashi, Yuichi; Kaneyasu, Tatsuo

    2012-08-01

    Practical effects of a hybrid three-pole wiggler on the beam was investigated at 1.4 GeV storage ring of Saga light source in the viewpoint of evaluation of the applicability of the wiggler on actual storage ring. The wiggler was developed to generate hard X-rays up to 40 keV approximately. The magnet system consisted of three isolated poles—a superconducting main pole and two normal-conducting side poles. To suppress the increase in the second magnetic field integral caused by the isolated pole structure, thick field clamps that generate a negative field for the main pole were located at both ends of the main pole. This isolated pole structure with field clamps generated an unusual field distribution. The practical effects of the wiggler field on the storage ring (e.g., the focusing force, the sextupole strength, radiation power and the beam emittance ) were investigated by performing measurements. The results agreed roughly with practical field calculation model, which was corrected by result of the magnetic field measurement. Practical multipole effects were relatively tolerable or controllable. In addition, the employment of the field clamps and the normal-conducting side pole, which contributed to the decrease of peak field of the side poles, brought about reduction of beam effects due to curvature distribution at the side poles.

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

    PubMed

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

    2015-03-01

    Energy loss in the transport of a beam of relativistic electrons in warm dense aluminum is measured in the regime of ultrahigh electron beam current density over 2×10^{11}  A/cm^{2} (time averaged). The samples are heated by shock compression. Comparing to undriven cold solid targets, the roles of the different initial resistivity and of the transient resistivity (upon target heating during electron transport) are directly observable in the experimental data, and are reproduced by a comprehensive set of simulations describing the hydrodynamics of the shock compression and electron beam generation and transport. We measured a 19% increase in electron resistive energy loss in warm dense compared to cold solid samples of identical areal mass. PMID:25793822

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

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

    SciTech Connect

    Guaglio, G.; Dehning, B.; Santoni, C.

    2004-11-10

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

  10. SIMULATION STUDY AND INITIAL TEST OF THESNS RING RF SYSTEM

    SciTech Connect

    Zhang, Yan; Ma, Hengjie; Holmes, Jeffrey A; Champion, Mark; Chu, Paul; Cousineau, Sarah M; Hardek, Thomas W; Plum, Michael A; Danilov, Viatcheslav; Piller, Chip

    2008-01-01

    The rfsimulator code was developed for the study of the Spallation Neutron Source (SNS) dual-harmonic ring RF control. It uses time-domain solvers to compute beam-cavity interactions and FFT methods to simulate the time responses of the linear RF system. The important elements of the system considered in the model include beam loading, dynamic cavity detuning, circuit bandwidth, loop delay, proportional-integral controller for feedback and adaptive feed forward, stochastic noise, width-in-turn loop parameter change, beam current fluctuation, and bunch leakage. As the beam power increases, beam loss in the ring goes up and thus precise control of the bunching RF phase and amplitude is required to limit beam loss. The code will help in the development of a functional RF control and in achieving the goal of minimizing beam loss in the accumulator ring.

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

    PubMed Central

    Gwin, Joseph T.; Makeig, Scott; Ferris, Daniel P.

    2013-01-01

    Determining the neural correlates of loss of balance during walking could lead to improved clinical assessment and treatment for individuals predisposed to falls. We used high-density electroencephalography (EEG) combined with independent component analysis (ICA) to study loss of balance during human walking. We examined 26 healthy young subjects performing heel-to-toe walking on a treadmill-mounted balance beam as well as walking on the treadmill belt (both at 0.22 m/s). ICA identified clusters of electrocortical EEG sources located in or near anterior cingulate, anterior parietal, superior dorsolateral-prefrontal, and medial sensorimotor cortex that exhibited significantly larger mean spectral power in the theta band (4–7 Hz) during walking on the balance beam compared with treadmill walking. Left and right sensorimotor cortex clusters produced significantly less power in the beta band (12–30 Hz) during walking on the balance beam compared with treadmill walking. For each source cluster, we also computed a normalized mean time/frequency spectrogram time locked to the gait cycle during loss of balance (i.e., when subjects stepped off the balance beam). All clusters except the medial sensorimotor cluster exhibited a transient increase in theta band power during loss of balance. Cluster spectrograms demonstrated that the first electrocortical indication of impending loss of balance occurred in the left sensorimotor cortex at the transition from single support to double support prior to stepping off the beam. These findings provide new insight into the neural correlates of walking balance control and could aid future studies on elderly individuals and others with balance impairments. PMID:23926037

  12. Commissioning results of the narrow-band beam position monitor system upgrade in the APS storage ring.

    SciTech Connect

    Singh, O.

    1999-04-20

    When using a low emittance storage ring as a high brightness synchrotron radiation source, it is critical to maintain a very high degree of orbit stability, both for the short term and for the duration of an operational fill. A fill-to-fill reproducibility is an additional important requirement. Recent developments in orbit correction algorithms have provided tools that are capable of achieving a high degree of orbit stability. However, the performance of these feedback systems can be severely limited if there are errors in the beam position monitors (BPMs). The present orbit measurement and correction system at the APS storage ring utilizes 360 broad-band-type BPMs that provide turn-by-turn diagnostics and an ultra-stable orbit: < 1.8 micron rms vertically and 4.5 microns rms horizontally in a frequency band of 0.017 to 30 Hz. The effects of beam intensity and bunch pattern dependency on these BPMs have been significantly reduced by employing offset compensation correction. Recently, 40 narrow-band switching-type BPMs have been installed in the APS storage ring, two in each of 20 operational insertion device straight sections, bringing the total number of beam position monitors to 400. The use of narrow-band BPM electronics is expected to reduce sensitivity to beam intensity, bunch pattern dependence, and long-term drift. These beam position monitors are used for orbit correction/feedback and machine protection interlocks for the insertion device beamlines. The commissioning results and overall performance for orbit stability are provided.

  13. Halo and space charge issues in the SNS Ring

    SciTech Connect

    Fedotov, A.V.; Abell, D.T.; Beebe-Wang, J.; Lee, Y.Y.; Malitsky, N.; Wei, J.; Gluckstern, R.L.

    2000-06-30

    The latest designs for high-intensity proton rings require minimizing beam-induced radioactivation of the vacuum chamber. Although the tune depression in the ring is much smaller than in high-intensity linacs, space-charge contributions to halo formation and, hence, beam loss may be significant. This paper reviews our current understanding of halo formation issues for the Spallation Neutron Source (SNS) accumulator ring.

  14. Radiation Safety Design for SSRL Storage Ring

    SciTech Connect

    Khater, Hesham; Liu, James; Fasso, Alberto; Prinz, Alyssa; Rokni, Sayed; /SLAC

    2007-02-12

    In 2003, the Stanford Synchrotron Radiation Laboratory (SSRL) has upgraded its storage ring to a 3rd generation storage ring (SPEAR3). SPEAR3 is deigned to operate at 500 mA stored beam current and 3 GeV energy. The 234-meter circumference SPEAR3 ring utilizes 60-cm-thick concrete lateral walls, 30-cm-thick concrete roof, as well as 60-cm or 90-cm-thick concrete ratchet walls. A total of 3.5 x 10{sup 15} e{sup -}/y will be injected into the ring with an injection power of 4 W and an injection efficiency of 75%. Normal beam losses occur due to both injection and stored beam operations in the total of 20 low loss as well as 3 high loss limiting apertures. During the 6-minutes injection period, an instantaneous power loss of 0.05 W occurs at each low loss aperture. When averaged over the operational year, the loss of both the injection and stored beams is equivalent to an average loss of 2 mW at each low loss aperture. On the other hand, the average losses in the high loss apertures are 16 mW for the injection septum, 47 mW for the beam abort dump, and 13 mW for the ring stoppers. The shielding requirements for losses in the new ring were based on a generic approach that used both FLUKA Monte Carlo particle generation and transport code and empirical computer codes and formulae.

  15. Interaction of counterpropagating circularly polarized waves in an He--Ne ring laser with a gain greatly exceeding its losses

    SciTech Connect

    Mogil'naya, T.Y.; Savel'ev, I.I.; Timonin, P.V.; Yakushev, A.I.

    1983-10-01

    A theoretical and experimental investigation was made of the interaction between counterpropagating waves in an He--Ne ring laser having a circularly anisotropic resonator. This was done for large values of the ratio of the gain to the losses when the gain saturation was comparable with the gain itself. The dependences of the counterpropagating wave intensities and of the frequency of beats (formed when a longitudinal magnetic field was applied to the active medium) on the resonator detuning in a single-mode 0.63 ..mu.. wavelength laser were obtained experimentally. Numerically found theoretical dependences were in good agreement with experiment for values of the ratio of the gain to the losses of up to 2.9.

  16. Exact Analytical Solutions of Continuity Equation for Electron Beams Precipitating in Ohmic and Mixed Energy Losses

    NASA Astrophysics Data System (ADS)

    Dobranskis, Rytis; Zharkova, Valentina

    2015-04-01

    In this paper we extend the approach presented in Dobranskis & Zharkova (2014a,b) by updating the analytical solutions of continuity equation (CE) for pure Ohmic losses and developing a method for analytical solutions to account simultaneously for both collisional and Ohmic losses. The exact solutions of CE for electron density of the beams precipitating in Ohmic losses are found at different precipitation depths for precipitating and "returning") electrons. Then the iterative process was applied to calculate the differential density for mixed (Ohmic and collisional) energy losses (MEL). The differential densities obtained from the updated CE for Coulomb collisions and MEL are used to calculate the HXR intensity for relativistic cross-section and to compare the outcome with more accurate results found from the numerical Fokker-Planck (FP) solution for the same collisional and Ohmic losses. The HXR intensity distribution produced by MEL solution reveals a close resemblance to the results from the numerical FP solution, being almost identical for weaker soft electron beams. However, the MEL simulation can be run up to 30 times faster than the numerical FP. This method implemented in IDL is to be incorporated into the RHESSI software that can be used for quick estimation of the effect of Ohmic losses versus collisions from the RHESSI data.

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

    SciTech Connect

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Strašík, I.; Mustafin, E.; Pavlovič, M.

    2010-07-01

    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 200MeV/u up to 1GeV/u.

  20. Measuring correlations between beam loss and residual radiation in the Fermilab Main Injector

    SciTech Connect

    Brown, Bruce C.; Wu, Guan Hong; /Fermilab

    2010-09-01

    In order to control beam loss for high intensity operation of the Fermilab Main Injector, electronics has been implemented to provide detailed loss measurements using gas-filled ionization monitors. Software to enhance routine operation and studies has been developed and losses are logged for each acceleration cycle. A systematic study of residual radiation at selected locations in the accelerator tunnel have been carried out by logging residual radiation at each of 142 bar-coded locations. We report on fits of the residual radiation measurements to half-life weighted sums of the beam loss data using a few characteristic lifetimes. The data are now available over a multi-year period including residual radiation measurements repeated multiple times during three extended facility shutdown periods. Measurement intervals of a few weeks combined with variable delays between beam off time and the residual measurement permits sensitivity to lifetimes from hours to years. The results allow planning for work in radiation areas to be based on calibrated analytic models.

  1. Polarisation splitting of laser beams by large angles with minimal reflection losses

    SciTech Connect

    Davydov, B L

    2006-05-31

    New crystal anisotropic prisms for splitting orthogonally polarised components of laser radiation by large angles with minimal reflection losses caused by the Brewster refraction and total internal reflection of polarised waves from the crystal-air interface are considered and the method for their calculation is described. It is shown that, by assembling glue-free combinations of two or three prisms, thermally stable beamsplitters can be fabricated, which are free from the beam astigmatism and the wave dispersion of the output angles of the beams. The parameters and properties of new beamsplitters are presented in a convenient form in figures and tables. (laser applications and other topics in quantum electronics)

  2. Modeling of beam loss in Tevatron and backgrounds in the BTeV detector

    SciTech Connect

    Alexandr I. Drozhdin; Nikolai V. Mokhov

    2004-07-07

    Detailed STRUCT simulations are performed on beam loss rates in the vicinity of the BTeV detector in the Tevatron CO interaction region due to beam-gas nuclear elastic interactions and out-scattering from the collimation system. Corresponding showers induced in the machine components and background rates in BTeV are modeled with the MARS14 code. It is shown that the combination of a steel collimator and concrete shielding wall located in front of the detector can reduce the accelerator-related background rates in the detector by an order of magnitude.

  3. Long-Range Beam-Beam Compensation in RHIC

    SciTech Connect

    Kim, Hyung Jin; Sen, Tanaji; Fischer, Wolfram; /Brookhaven

    2010-05-01

    In order to avoid the effects of long-range beam-beam interactions which produce beam blow-up and deteriorate beam life time, a compensation scheme with current carrying wires has been proposed. Two long-range beam-beam compensators were installed in RHIC rings in 2006. The effects of the compensators have been experimentally investigated. An indication was observed that the compensators are beneficial to beam life time in measurements performed in RHIC during 2009. In this paper, we report the effects of wire compensator on beam loss and emittance for proton-proton beams at collision energy.

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

    PubMed

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

    2016-02-01

    NIO1 (Negative Ion Optimization 1) is a versatile ion source designed to study the physics of production and acceleration of H- beams up to 60 keV. In ion sources, the gas is steadily injected in the plasma source to sustain the discharge, while high vacuum is maintained by a dedicated pumping system located in the vessel. In this paper, the three dimensional gas flow in NIO1 is studied in the molecular flow regime by the Avocado code. The analysis of the gas density profile along the accelerator considers the influence of effective gas temperature in the source, of the gas temperature accommodation by collisions at walls, and of the gas particle mass. The calculated source and vessel pressures are compared with experimental measurements in NIO1 during steady gas injection. PMID:26932000

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    SciTech Connect

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

    2014-08-04

    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.

  7. Radiative interaction of a focused relativistic electron beam in energy-loss spectroscopy of nanoscopic platelets

    SciTech Connect

    Itskovsky, M. A.; Maniv, T.; Cohen, H.

    2008-07-15

    A quantum-mechanical scattering theory for relativistic, highly focused electron beams in the vacuum near nanoscopic platelets is presented, revealing an excitation mechanism due to the electron wave scattering from the platelet edges. Radiative electromagnetic excitations within the light cone are shown to arise, allowed by the breakdown of momentum conservation along the beam axis in the inelastic-scattering process. Calculated for metallic (silver and gold) and insulating (SiO{sub 2} and MgO) nanoplatelets, radiative features are revealed above the main surface-plasmon-polariton peak, and dramatic enhancements in the electron-energy-loss probability at gaps of the 'classical' spectra are found. The corresponding radiation should be detectable in the vacuum far-field zone, with e beams exploited as sensitive 'tip detectors' of electronically excited nanostructures.

  8. Energetic ring current ion spectra shaped by EMIC wave scattering loss

    NASA Astrophysics Data System (ADS)

    Summers, Danny; Shi, Run

    2016-07-01

    We address the problem of determining the limiting energetic ring current ion spectrum resulting from electromagnetic ion cyclotron (EMIC)-wave-ion-interactions. We solve the problem in a relativistic regime,incorporating a cold background multi-ion plasma component and without assuming a predetermined form for the particle energy distribution. The limiting spectrum is determined by the condition that the EMIC waves acquire a certain gain over a given convective length scale for all frequencies over which wave growth occurs. We find that the limiting ion spectrum satisfies an integral equation that must be solved numerically. However, at large particle energy E, the limiting spectrum varies simply as 1/E. Moreover,this spectral shape does not depend on the energetic ion in question nor on the background multi-ion plasma composition. We provide numerical solutions for the limiting spectra for Earth-like parameters, and we compare measured ion spectra from the Van Allen Probes with corresponding numerical limiting spectra.

  9. Integrated InP-InGaAsP tunable coupled ring optical bandpass filters with zero insertion loss.

    PubMed

    Guzzon, Robert S; Norberg, Erik J; Parker, John S; Johansson, Leif A; Coldren, Larry A

    2011-04-11

    Second and third-order monolithically integrated coupled ring bandpass filters are demonstrated in the InP-InGaAsP material system with active semiconductor optical amplifiers (SOAs) and current injection phase modulators (PMs). Such integration achieves a high level of tunability and precise generation of optical filters in the RF domain at telecom wavelengths while simultaneously compensating for device insertion loss. Passband bandwidth tunability of 3.9 GHz to 7.1 GHz and stopband extinction up to 40 dB are shown for third-order filters. Center frequency tunability over a full free spectral range (FSR) is demonstrated, allowing for the placement of a filter anywhere in the telecom C-band. A Z-transform representation of coupled resonator filters is derived and compared with experimental results. A theoretical description of filter tunability is presented. PMID:21503092

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

    NASA Astrophysics Data System (ADS)

    Engholm, Cynthia D.; Troxel, Seth W.

    1990-10-01

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

  11. Beam-beam instability

    SciTech Connect

    Chao, A.W.

    1983-08-01

    The subject of beam-beam instability has been studied since the invention of the colliding beam storage rings. Today, with several colliding beam storage rings in operation, it is not yet fully understood and remains an outstanding problem for the storage ring designers. No doubt that good progress has been made over the years, but what we have at present is still rather primitive. It is perhaps possible to divide the beam-beam subject into two areas: one on luminosity optimization and another on the dynamics of the beam-beam interaction. The former area concerns mostly the design and operational features of a colliding beam storage ring, while the later concentrates on the experimental and theoretical aspects of the beam-beam interaction. Although both areas are of interest, our emphasis is on the second area only. In particular, we are most interested in the various possible mechanisms that cause the beam-beam instability.

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

    NASA Astrophysics Data System (ADS)

    Bhat, C. M.

    2014-06-01

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

  13. Cavity ring-down spectroscopy sensor for ion beam etch monitoring and end-point detection of multilayer structures.

    PubMed

    Tao, L; Yalin, A P; Yamamoto, N

    2008-11-01

    This contribution reports on the development of in situ sputter monitoring and end-point detection for ion beam etch systems using continuous-wave cavity ring-down spectroscopy (cw-CRDS). The demonstrated system is based on the detection of sputtered manganese atoms using a tunable external cavity diode laser in the vicinity of 403.07 nm. The cw-CRDS system is described and measurements from a manganese-iron target are presented. End-point detection is demonstrated by monitoring the time dependence of manganese concentration for a multilayer target comprised of alternating layers of manganese/iron and titanium. Detection limits are shown to be adequate for today's commercial ion beam sputter systems. PMID:19045913

  14. Implementation status of the global and local beam position feedback systems for the Advanced Photon Source storage ring

    SciTech Connect

    Chung, Y.; Barr, D.; Decker, G.; Galayda, J.; Kirchman, J.; Lenkszus, F.; Lumpkin, A.; Votaw, A.J.

    1995-07-01

    The Advanced Photon Source (APS) is implementing an extensive beam position feedback system for both global and local stabilization of particle and photon beams based on digital signal processing. The description and operational experience of the system will be given in this paper. In particular, we will discuss the underlying fundamental principles, hardware layout, controls interface, and automatic software generation for multiple digital signal processors (DSPS) distributed in 20 VME crates around the ring. The feedback system runs at 4-kHz sampling frequency in order to achieve the correction bandwidth of approximately 100 Hz. For the maximum correction efficiency and resolution of conflicts among multiple local feedback systems due to the local bump closure error, the global and local feedback systems are combined into a single unified system. This novel approach is made possible through data sharing among the global and local systems via the fiber-optically networked reflective memories.

  15. Effects of magnetic non-linearities on a stored proton beam and their implications for superconducting storage rings

    SciTech Connect

    Cornacchia, M.; Evans, L.

    1985-06-01

    A nonlinear lens may be used to study the effect of high-order multipolar field imperfections on a stored proton beam. Such a nonlinear lens is particulary suitable to simulate field imperfections of the types encountered in coil dominated superconducting magnets. We have studied experimentally at the SPS the effect of high order (5th and 8th) single isolated resonances driven by the nonlinear lens. The width of these resonances is of the order one expects to be caused by field errors in superconducting magnets of the SSC type. The experiment shows that, in absence of tune modulation, these resonances are harmless. Slow crossings of the resonance, on the other hand, have destructive effects on the beam, much more so than fast crossings caused by synchrotron oscillations. In the design of future storage rings, sources of low-frequency tune modulation should be avoided as a way to reduce the harmful effects of high order multipolar field imperfection.

  16. Laser Compton Scattering Gamma-Ray Beam Source at NewSUBARU Storage Ring

    NASA Astrophysics Data System (ADS)

    Miyamoto, S.; Amano, S.; Hashimoto, S.; Sakai, N.; Koizumi, A.; Hashimoto, T.; Shizuma, T.; Utsunomiya, H.; Yamagata, T.; Akimune, H.; Shima, T.; Li, D.; Asano, Y.; Ohkuma, H.

    2015-10-01

    Laser Compton scattering gamma-ray beam source has been developed at the NewSUBARU synchrotron light facility. The available maximum Gamma-ray photon energy is 76 MeV. The flux of quasi-monochromatic gamma-ray photons (for example: 16.7 MeV, ΔE/E ~ 5%) is more than 106photons/sec using a 35 W Nd:YVO4 laser combined with the 1 GeV storage electron beam with an intensity of 300 mA. We used the electron beams at Ee = 0.55 ~ 1.47 GeV for changing the energy of quasi-monochromatic gamma-ray beam. Gamma-ray beams were used for application experiments, a nuclear physics research, a nondestructive inspection of thick material, a generation of positron by pair creation, a magnetic Compton scattering measurements, and a nuclear transmutation.

  17. Harmonic generation in VUV/x-ray range at the Duke storage ring FEL using electron beam outcoupling

    SciTech Connect

    Litvinenko, V.N.; Burnham, B.; Madey, J.M.J.

    1995-12-31

    We suggest using the OK-4 FEL operating in giant pulse mode to generate intracavity optical power at a level of hundreds of megawatts. These levels of power are sufficient to generate harmonics in the electron beam density. The prebunched electron beam then radiates coherently in an additional wiggler which is tuned on a harmonic of the OK-4 wavelength. The electron beam is turned by an achromatic bend into this wiggler, and harmonic radiation propagates with a small angle with respect to the OK-4 optical axis. This radiation will pass around the mirror of the OK-4 optical cavity and can then be utilized. This electron outcoupling scheme was suggested by N.A. Vinokurov as a method of optics independent outcoupling for high power FELs where electron beam bunching is provided in the master oscillator. This scheme is perfectly suited for optics independent harmonic generation. We suggest to operate the OK-4 FEL as a master oscillator in the UV range of 100 to 250 nm where conventional optics are available. This harmonic generation scheme would allow us to cover the VUV and soft X-Ray range with tunable coherent radiation. In this paper we present the possible layout of this system at the Duke storage ring and its expected operating parameters.

  18. Study of Z > 18 elements concentration in tree rings from surroundings forests of the Mexico Valley using external beam PIXE

    NASA Astrophysics Data System (ADS)

    Calva-Vázquez, G.; Razo-Angel, G.; Rodríguez-Fernández, L.; Ruvalcaba-Sil, J. L.

    2006-08-01

    The concentration of elements with Z > 18 is measured in tree rings from forests at the surroundings of the Mexico Valley: El Chico National Park (ECP) and Desierto de los Leones National Park (DLP). The analysis was done by simultaneous PIXE-RBS using an external proton beam on tree rings of Pine and Sacred fir (species Pinus montezumae and Abies religiosa, respectively). This study provides information about the elemental concentration in trees of those parks during the years from 1965 to 2003. Typical elements such as K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Sr and Pb were detected using PIXE technique while the wood matrix composition (mainly C and O) was determined by RBS. In general, elemental contents present large variations but concentrations oscillate around the mean value during this period of time. Nevertheless, the measurements showed some trends for Fe and Zn in the tree-rings elemental composition that may be correlated to recent volcanic activities in the region. The low Mn contents indicate soil acidification in DLP from 1968 and the forest decline in ECP during the last 15 years.

  19. Loss-proof self-accelerating beams and their use in non-paraxial manipulation of particles' trajectories.

    PubMed

    Schley, Ran; Kaminer, Ido; Greenfield, Elad; Bekenstein, Rivka; Lumer, Yaakov; Segev, Mordechai

    2014-01-01

    Self-accelerating beams--shape-preserving bending beams--are attracting great interest, offering applications in many areas such as particle micromanipulation, microscopy, induction of plasma channels, surface plasmons, laser machining, nonlinear frequency conversion and electron beams. Most of these applications involve light-matter interactions, hence their propagation range is limited by absorption. We propose loss-proof accelerating beams that overcome linear and nonlinear losses. These beams, as analytic solutions of Maxwell's equations with losses, propagate in absorbing media while maintaining their peak intensity. While the power such beams carry decays during propagation, the peak intensity and the structure of their main lobe region are maintained over large distances. We use these beams for manipulation of particles in fluids, steering the particles to steeper angles than ever demonstrated. Such beams offer many additional applications, such as loss-proof self-bending plasmons. In transparent media these beams show exponential intensity growth, which facilitates other novel applications in micromanipulation and ignition of nonlinear processes. PMID:25355605

  20. Thon rings from amorphous ice and implications of beam-induced Brownian motion in single particle electron cryo-microscopy.

    PubMed

    McMullan, G; Vinothkumar, K R; Henderson, R

    2015-11-01

    We have recorded dose-fractionated electron cryo-microscope images of thin films of pure flash-frozen amorphous ice and pre-irradiated amorphous carbon on a Falcon II direct electron detector using 300 keV electrons. We observe Thon rings [1] in both the power spectrum of the summed frames and the sum of power spectra from the individual frames. The Thon rings from amorphous carbon images are always more visible in the power spectrum of the summed frames whereas those of amorphous ice are more visible in the sum of power spectra from the individual frames. This difference indicates that while pre-irradiated carbon behaves like a solid during the exposure, amorphous ice behaves like a fluid with the individual water molecules undergoing beam-induced motion. Using the measured variation in the power spectra amplitude with number of electrons per image we deduce that water molecules are randomly displaced by a mean squared distance of ∼1.1 Å(2) for every incident 300 keV e(-)/Å(2). The induced motion leads to an optimal exposure with 300 keV electrons of 4.0 e(-)/Å(2) per image with which to observe Thon rings centred around the strong 3.7 Å scattering peak from amorphous ice. The beam-induced movement of the water molecules generates pseudo-Brownian motion of embedded macromolecules. The resulting blurring of single particle images contributes an additional term, on top of that from radiation damage, to the minimum achievable B-factor for macromolecular structure determination. PMID:26103047

  1. Thon rings from amorphous ice and implications of beam-induced Brownian motion in single particle electron cryo-microscopy

    PubMed Central

    G. McMullan; Vinothkumar, K.R.; Henderson, R.

    2015-01-01

    We have recorded dose-fractionated electron cryo-microscope images of thin films of pure flash-frozen amorphous ice and pre-irradiated amorphous carbon on a Falcon II direct electron detector using 300 keV electrons. We observe Thon rings [1] in both the power spectrum of the summed frames and the sum of power spectra from the individual frames. The Thon rings from amorphous carbon images are always more visible in the power spectrum of the summed frames whereas those of amorphous ice are more visible in the sum of power spectra from the individual frames. This difference indicates that while pre-irradiated carbon behaves like a solid during the exposure, amorphous ice behaves like a fluid with the individual water molecules undergoing beam-induced motion. Using the measured variation in the power spectra amplitude with number of electrons per image we deduce that water molecules are randomly displaced by a mean squared distance of ∼1.1 Å2 for every incident 300 keV e−/Å2. The induced motion leads to an optimal exposure with 300 keV electrons of 4.0 e−/Å2 per image with which to observe Thon rings centred around the strong 3.7 Å scattering peak from amorphous ice. The beam-induced movement of the water molecules generates pseudo-Brownian motion of embedded macromolecules. The resulting blurring of single particle images contributes an additional term, on top of that from radiation damage, to the minimum achievable B-factor for macromolecular structure determination. PMID:26103047

  2. Perturbation of the energy loss spectra for an accelerated electron beam due to the photo injector exit

    NASA Astrophysics Data System (ADS)

    Salah, W.

    2003-01-01

    The influence of the photoinjector exit hall on the energy loss for an accelerated electron beam is investigated, by calculating the total energy transferred from the electrons to the wakefields, which are driven by the beam. The obtained energy loss is compared to those previously obtained for a `pill-box' cavity [CITE]. This comparison shows that the influence of this hall, in terms of energy loss, varies over the beam length. It is strongest in the middle of the beam and decreases towards both ends. In consequence of this perturbation, the center of the beam is displaced from its initial position during the first phase (t < 200 ps) where the exit aperture has no effect to a new equilibrium position which takes place at 200 < t < 250 ps.

  3. INDEPENDENT COMPONENT ANALYSIS (ICA) APPLIED TO LONG BUNCH BEAMS IN THE LOS ALAMOS PROTON STORAGE RING

    SciTech Connect

    Kolski, Jeffrey S.; Macek, Robert J.; McCrady, Rodney C.; Pang, Xiaoying

    2012-05-14

    Independent component analysis (ICA) is a powerful blind source separation (BSS) method. Compared to the typical BSS method, principal component analysis (PCA), which is the BSS foundation of the well known model independent analysis (MIA), ICA is more robust to noise, coupling, and nonlinearity. ICA of turn-by-turn beam position data has been used to measure the transverse betatron phase and amplitude functions, dispersion function, linear coupling, sextupole strength, and nonlinear beam dynamics. We apply ICA in a new way to slices along the bunch and discuss the source signals identified as betatron motion and longitudinal beam structure.

  4. Positron versus electron-beam quality in low emittance storage rings (invited)

    NASA Astrophysics Data System (ADS)

    Marin, P. C.

    1992-01-01

    A brief summary of ion trapping dependence and its effects is first presented. Based on the experience of Super-ACO, the benefits at different stages of commissioning a synchrotron radiation facility with positrons are then reviewed for the running in period and later, for beam physics studies. Most important appears to be the trapping of nonconductive dust particles in electron beams and its consequences: microlosses, reduced lifetime, and beam emittance growth. A simple model based on photoionization and Möller scattering leads to several predictions which have been tested at Super-ACO. Experimental evidences are presented.

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

    SciTech Connect

    Darrow, D. S.; Crocker, N.; Fredrickson, E. D.; Gorelenkov, N. N.; Gorelenkova, M.; Kubota, S.; Medley, S. S.; Podestà, M.; Shi, L.; White, R. B.

    2012-12-17

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

  6. Radiation Handling in the Slow Extraction of the JHF 50 GeV Ring

    NASA Astrophysics Data System (ADS)

    Yokoi, Takeichiro; Tomizawa, Masahito

    2002-12-01

    In the slow extraction of the JHF 50GeV ring, about 1 is expected to hit the ESS(Electro Static Septum). The beam loss in the scattering is about 1% corresponding to the beam power of 7.5kW. Considering the tolerable beam loss(0.5˜1W/m), careful study of the beam loss of the scattering beam is indispensable. To evaluate the radiation level around ESS, simulation study with MARS14(00), was carried out. In addition, the beam loss distribution in the ring was studied combining MARS14(00) and single particle tracking. The result shows that the radiation level around ESS is suppressed to the tolerable level. In addition, it was found that the actual beam loss is much smaller than the loss of 1% which hit the ESS wire.

  7. Modal analysis of the energy loss for an accelerated electron beam passing through a laser-driven RF gun

    NASA Astrophysics Data System (ADS)

    Salah, W.

    2002-06-01

    The energy loss for an accelerated electron beam passing through a laser-driven RF gun has been studied. An analytical formula of the energy loss has been obtained using the time-dependent resonant modes of a cylindrical "pill-box" cavity. As an approximation, this formalism assumes a rigid beam pulse so the change of pulse shape dealing with space-charge force and wake field force is ignored.

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

    SciTech Connect

    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.

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

    SciTech Connect

    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

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  11. Accuracy of Cone Beam Computed Tomography for Detection of Bone Loss

    PubMed Central

    Goodarzi Pour, Daryoush; Soleimani Shayesteh, Yadollah

    2015-01-01

    Objectives: Bone assessment is essential for diagnosis, treatment planning and prediction of prognosis of periodontal diseases. However, two-dimensional radiographic techniques have multiple limitations, mainly addressed by the introduction of three-dimensional imaging techniques such as cone beam computed tomography (CBCT). This study aimed to assess the accuracy of CBCT for detection of marginal bone loss in patients receiving dental implants. Materials and Methods: A study of diagnostic test accuracy was designed and 38 teeth from candidates for dental implant treatment were selected. On CBCT scans, the amount of bone resorption in the buccal, lingual/palatal, mesial and distal surfaces was determined by measuring the distance from the cementoenamel junction to the alveolar crest (normal group: 0–1.5mm, mild bone loss: 1.6–3mm, moderate bone loss: 3.1–4.5mm and severe bone loss: >4.5mm). During the surgical phase, bone loss was measured at the same sites using a periodontal probe. The values were then compared by McNemar’s test. Results: In the buccal, lingual/palatal, mesial and distal surfaces, no significant difference was observed between the values obtained using CBCT and the surgical method. The correlation between CBCT and surgical method was mainly based on the estimation of the degree of bone resorption. CBCT was capable of showing various levels of resorption in all surfaces with high sensitivity, specificity, positive predictive value and negative predictive value compared to the surgical method. Conclusion: CBCT enables accurate measurement of bone loss comparable to surgical exploration and can be used for diagnosis of bone defects in periodontal diseases in clinical settings. PMID:26877741

  12. Six-Dimensional Muon Beam Cooling Using Energy Loss in a Helical Channel

    SciTech Connect

    Kevin B. Beard; S. Alex Bogacz; Yaroslav S. Derbenev; Rolland P. Johnson

    2004-07-01

    The fast reduction of the six-dimensional phase space of muon beams is an essential requirement for muon colliders and also of great importance for neutrino factories based on accelerated muon beams. Considered cooling scheme involves the use of a continuous gaseous hydrogen absorber and a magnetic channel composed of a solenoidal field with superimposed helical transverse dipole and quadrupole fields. All momentum components of muons passing through the channel are degraded by an energy absorbing material and only the longitudinal momentum is restored by RF cavities, which yields a quick reduction of transverse beam sizes. In such a channel higher momentum muons cover longer path length and therefore experience larger ionization energy loss, which provides the desired emittance exchange mechanism. Recent theoretical work predicts exceptional six dimensional cooling in such a channel filled with a continuous hydrogen gas absorber [1]. Here we study the same channel, but without RF r e-acceleration, as the first stage of a muon cooling channel. The theory of this use of the helical channel is extended from the earlier work. Results from simulations based on the Geant4 program are compared to theoretical predictions.

  13. Ultrafast harmonic rf kicker design and beam dynamics analysis for an energy recovery linac based electron circulator cooler ring

    DOE PAGESBeta

    Huang, Yulu; Wang, Haipeng; Rimmer, Robert A.; Wang, Shaoheng; Guo, Jiquan

    2016-08-01

    An ultrafast kicker system is being developed for the energy recovery linac (ERL) based electron circulator cooler ring (CCR) in the proposed Jefferson Lab Electron Ion Collider (JLEIC, previously named MEIC). In the CCR, the injected electron bunches can be recirculated while performing ion cooling for 10–30 turns before the extraction, thus reducing the recirculation beam current in the ERL to 1/10–1/30 (150mA–50 mA) of the cooling beam current (up to 1.5 A). Assuming a bunch repetition rate of 476.3 MHz and a recirculating factor of 10 in the CCR, the kicker is required to operate at a pulse repetitionmore » rate of 47.63 MHz with pulse width of around 2 ns, so that only every 10th bunch in the CCR will experience a transverse kick while the rest of the bunches will not be disturbed. Such a kicker pulse can be synthesized by ten harmonic modes of the 47.63 MHz kicker pulse repetition frequency, using up to four quarter wavelength resonator (QWR) based deflecting cavities. In this paper, several methods to synthesize such a kicker waveform will be discussed and a comparison of their beam dynamics performance is made using ELEGANT. Four QWR cavities are envisaged with high transverse shunt impedance requiring less than 100 W of total rf power for a Flat-Top kick pulse. Multipole fields due to the asymmetry of this type of cavity are analyzed. The transverse emittance growth due to the sextupole component is simulated in ELEGANT. In conclusion, off-axis injection and extraction issues and beam optics using a multicavity kick-drift scheme will also be discussed.« less

  14. Recent transition crossing results from the Fermilab Main Ring

    SciTech Connect

    Bhat, C.M.; Ng, K.Y.

    1997-03-01

    This paper outlines the known mechanisms for emittance dilution and beam loss during transition crossing. These include scraping, Johnsen`s nonlinear effect, bunch length mismatch, microwave and negative-mass instabilities, and beam loading. A recent experiment on transition crossing performed with 13 proton bunches injected into the Main Ring is discussed.

  15. Analytical description of a Gaussian beam in a ring resonator with a nonplanar axial contour and an odd number of mirrors

    SciTech Connect

    Plachenov, A B; Radin, A M

    2011-01-31

    Stability conditions for a ring resonator with an odd number of mirrors and a nonplanar axial contour are studied analytically. New explicit expressions are derived to describe the transverse field distribution of the Gaussian mode with general astigmatism produced in this resonator. Field characteristics for a resonator with the specified parameters are calculated. (laser beams)

  16. 10 orders of magnitude current measurement digitisers for the CERN beam loss systems

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

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

    SciTech Connect

    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.

  18. Readout process and noise elimination firmware for the Fermilab beam loss system

    SciTech Connect

    Wu, Jinyuan; Baumbaugh, Alan; Drennan, Craig; Thurman-Keup, Randy; Lewis, Jonathan; Shi, Zonghan; /Fermilab

    2007-05-01

    In the Fermilab Beam Loss Monitor System, inputs from ion chambers are integrated for a short period of time, digitized and processed to create the accelerator abort request signals. The accelerator power supplies employing 3-phase 60Hz AC cause noise at various harmonics on our inputs which must be eliminated for monitoring purposes. During accelerator ramping, both the sampling frequency and the amplitudes of the noise components change. As such, traditional digital filtering can partially reduce certain noise components but not all. A nontraditional algorithm was developed in our work to eliminate remaining ripples. The sequencing in the FPGA firmware is conducted by a micro-sequencer core we developed: the Enclosed Loop Micro-Sequencer (ELMS). The unique feature of the ELMS is that it supports the ''FOR'' loops with pre-defined iterations at the machine code level, which provides programming convenience and avoids many micro-complexities from the beginning.

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

    SciTech Connect

    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-/ovr string/p option with a luminosity of 10/sup 31/ cm/sup - 2/ sec/sup -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.

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

    NASA Astrophysics Data System (ADS)

    Li, Quan-Feng; Guo, Bing-Qi; Zhang, Jie-Xi; Chen, Huai-Bi

    2008-07-01

    The beam dynamic code PARMELA was used to simulate the transportation process of accelerating electrons in S-band SW linacs with different energies of 2.5, 6 and 20 MeV. The results indicated that in the ideal condition, the percentage of electron beam loss was 50% in accelerator tubes. Also we calculated the spectrum, the location and angular distribution of the lost electrons. Calculation performed by Monte Carlo code MCNP demonstrated that the radiation distribution of lost electrons was nearly uniform along the tube axis, the angular distributions of the radiation dose rates of the three tubes were similar, and the highest leaking dose was at the angle of 160° with respect to the axis. The lower the energy of the accelerator, the higher the radiation relative leakage. For the 2.5 MeV accelerator, the maximum dose rate reached 5% of the main dose and the one on the head of the electron gun was 1%, both of which did not meet the eligible protection requirement for accelerators. We adopted different shielding designs for different accelerators. The simulated result showed that the shielded radiation leaking dose rates fulfilled the requirement. Supported by National Natural Science Foundation of China (10135040)

  1. Calculating the Loss factor of the LCLS Beam Line Elements for Ultra-Shrot Bunches

    SciTech Connect

    Novokhatski, A.; /SLAC

    2009-10-17

    The Linac Coherent Light Source (LCLS) is a SASE 1.5-15 {angstrom} x-ray Free-Electron Laser (FEL) facility. Since an ultra-short intense bunch is used in the LCLS operation one might suggest that wake fields, generated in the vacuum chamber, may have an effect on the x-ray production because these fields can change the beam particle energies thereby increasing the energy spread in a bunch. At LCLS a feedback system precisely controls the bunch energy before it enters a beam transport line after the linac. However, in the transport line and later in the undulator section the bunch energy and energy spread are not under feedback control and may change due to wake field radiation, which depends upon the bunch current or on a bunch length. The linear part of the energy spread can be compensated in the upstream linac; the energy loss in the undulator section can be compensated by varying the K-parameter of the undulators, however we need a precise knowledge of the wake fields in this part of the machine. Resistive wake fields are known and well calculated. We discuss an additional part of the wake fields, which comes from the different vacuum elements like bellows, BPMs, transitions, vacuum ports, vacuum valves and others. We use the code 'NOVO' together with analytical estimations for the wake potential calculations.

  2. RF SYSTEM FOR THE SNS ACCUMULATOR RING.

    SciTech Connect

    BLASKIEWICZ, M.; BRENNAN, J.M.; BRODOWSKI, J.; DELONG, J.; METH, M.; SMITH, K.; ZALTSMAN, A.

    2001-06-18

    During accumulation the RF beam current in the spallation neutron source ring rises from 0 to 50 amperes. A clean, 250 nanosecond gap is needed for the extraction kicker risetime. Large momentum spread and small peak current are needed to prevent instabilities and stopband related losses. A robust RF system meeting these requirements has been designed.

  3. Transverse instability at the recycler ring

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2004-10-01

    Sporadic transverse instabilities have been observed at the Fermilab Recycler Ring leading to increase in transverse emittances and beam loss. The driving source of these instabilities has been attributed to the resistive-wall impedance with space-charge playing an important role in suppressing Landau damping. Growth rates of the instabilities are computed. Remaining problems are discussed.

  4. Equilibrium Beam Invariants of an Electron Storage Ring with Linear x-y Coupling

    SciTech Connect

    Wu, Juhao; Nash, B.E.; Chao, A.W.; /SLAC

    2005-09-14

    In accelerators, it is common that the motion of the horizontal x-plane is coupled to that of the vertical y-plane. Such coupling will induce tune shifts and can cause instabilities. The damping and diffusion rates are also affected, which in turn will lead to a change in the equilibrium invariants. With the perturbative approach which is also used for synchrobetatron coupling [B. Nash, J.Wu, and A. Chao, work in progress], we study the x-y coupled case in this paper. Starting from the one-turn map, we give explicit formulae for the tune shifts, damping and diffusion rates, and the equilibrium invariants. We focus on the cases where the system is near the integer or half integer, and sum or difference resonances where small coupling can cause a large change in the beam distribution.

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

    NASA Astrophysics Data System (ADS)

    Yang, Xi; Huang, Xiaobiao

    2016-08-01

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

  6. High-quality 3D correction of ring and radiant artifacts in flat panel detector-based cone beam volume CT imaging

    NASA Astrophysics Data System (ADS)

    Abu Anas, Emran Mohammad; Kim, Jae Gon; Lee, Soo Yeol; Kamrul Hasan, Md

    2011-10-01

    The use of an x-ray flat panel detector is increasingly becoming popular in 3D cone beam volume CT machines. Due to the deficient semiconductor array manufacturing process, the cone beam projection data are often corrupted by different types of abnormalities, which cause severe ring and radiant artifacts in a cone beam reconstruction image, and as a result, the diagnostic image quality is degraded. In this paper, a novel technique is presented for the correction of error in the 2D cone beam projections due to abnormalities often observed in 2D x-ray flat panel detectors. Template images are derived from the responses of the detector pixels using their statistical properties and then an effective non-causal derivative-based detection algorithm in 2D space is presented for the detection of defective and mis-calibrated detector elements separately. An image inpainting-based 3D correction scheme is proposed for the estimation of responses of defective detector elements, and the responses of the mis-calibrated detector elements are corrected using the normalization technique. For real-time implementation, a simplification of the proposed off-line method is also suggested. Finally, the proposed algorithms are tested using different real cone beam volume CT images and the experimental results demonstrate that the proposed methods can effectively remove ring and radiant artifacts from cone beam volume CT images compared to other reported techniques in the literature.

  7. High-quality 3D correction of ring and radiant artifacts in flat panel detector-based cone beam volume CT imaging.

    PubMed

    Anas, Emran Mohammad Abu; Kim, Jae Gon; Lee, Soo Yeol; Hasan, Md Kamrul

    2011-10-01

    The use of an x-ray flat panel detector is increasingly becoming popular in 3D cone beam volume CT machines. Due to the deficient semiconductor array manufacturing process, the cone beam projection data are often corrupted by different types of abnormalities, which cause severe ring and radiant artifacts in a cone beam reconstruction image, and as a result, the diagnostic image quality is degraded. In this paper, a novel technique is presented for the correction of error in the 2D cone beam projections due to abnormalities often observed in 2D x-ray flat panel detectors. Template images are derived from the responses of the detector pixels using their statistical properties and then an effective non-causal derivative-based detection algorithm in 2D space is presented for the detection of defective and mis-calibrated detector elements separately. An image inpainting-based 3D correction scheme is proposed for the estimation of responses of defective detector elements, and the responses of the mis-calibrated detector elements are corrected using the normalization technique. For real-time implementation, a simplification of the proposed off-line method is also suggested. Finally, the proposed algorithms are tested using different real cone beam volume CT images and the experimental results demonstrate that the proposed methods can effectively remove ring and radiant artifacts from cone beam volume CT images compared to other reported techniques in the literature. PMID:21934193

  8. Investigations on ring-shaped pumping distributions for the generation of beams with radial polarization in an Yb:YAG thin-disk laser.

    PubMed

    Dietrich, Tom; Rumpel, Martin; Graf, Thomas; Ahmed, Marwan Abdou

    2015-10-01

    We present experimental investigations on the generation of radially polarized laser beams excited by a ring-shaped pump intensity distribution in combination with polarizing grating waveguide mirrors in an Yb:YAG thin-disk laser resonator. Hollow optical fiber components were implemented in the pump beam path to transform the commonly used flattop pumping distribution into a ring-shaped distribution. The investigation was focused on finding the optimum mode overlap between the ring-shaped pump spot and the excited first order Laguerre-Gaussian (LG(01)) doughnut mode. The power, efficiency and polarization state of the emitted laser beam as well as the thermal behavior of the disk was compared to that obtained with a standard flattop pumping distribution. A maximum output power of 107 W with a high optical efficiency of 41.2% was achieved by implementing a 300 mm long specially manufactured hollow fiber into the pump beam path. Additionally it was found that at a pump power of 280 W the maximum temperature increase is about 21% below the one observed with standard homogeneous pumping. PMID:26480177

  9. High power, high beam quality regenerative amplifier

    DOEpatents

    Hackel, Lloyd A.; Dane, Clifford B.

    1993-01-01

    A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

  10. High power, high beam quality regenerative amplifier

    DOEpatents

    Hackel, L.A.; Dane, C.B.

    1993-08-24

    A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

  11. Induced radioactivity and its relation to beam losses in the CERN 26 GeV proton synchrotron

    NASA Astrophysics Data System (ADS)

    Sullivan, A. H.

    1987-06-01

    The results of induced radioactivity measurements made over the past 10 years around the CERN 26 GeV proton synchrotron are presented. The dose rate near different sections of the machine is shown to vary by factors up to 10 above and below the mean. A correlation is made between beam losses and radiation level, where it is estimated that to a first approximation in a machine that has been running a few years, the dose rate at 50 cm from a straight section between magnets and 24 h after stop will be 1.0 mSv/h (100 mrem/h) for beam losses equivalent to 1 W per meter of machine circumference. The dose rate after a cooling time of t days ( t ≪ 1 yr) is derived to be: D=p(1-0.4 log10t) mSv/h, where p is the average beam power loss, in W per m of circumference, over the two preceding months. This dependence of dose rate on decay time is compared with measured data from the PS for up to 43 days of cooling time. Beam losses estimated from induced activity dose rates using the above relation are shown to correspond reasonably with those expected for two operating conditions of the CERN 26 GeV proton synchrotron.

  12. Electron Beam Return-Current Losses in Solar Flares: Initial Comparison of Analytical and Numerical Results

    NASA Technical Reports Server (NTRS)

    Holman, Gordon

    2010-01-01

    Accelerated electrons play an important role in the energetics of solar flares. Understanding the process or processes that accelerate these electrons to high, nonthermal energies also depends on understanding the evolution of these electrons between the acceleration region and the region where they are observed through their hard X-ray or radio emission. Energy losses in the co-spatial electric field that drives the current-neutralizing return current can flatten the electron distribution toward low energies. This in turn flattens the corresponding bremsstrahlung hard X-ray spectrum toward low energies. The lost electron beam energy also enhances heating in the coronal part of the flare loop. Extending earlier work by Knight & Sturrock (1977), Emslie (1980), Diakonov & Somov (1988), and Litvinenko & Somov (1991), I have derived analytical and semi-analytical results for the nonthermal electron distribution function and the self-consistent electric field strength in the presence of a steady-state return-current. I review these results, presented previously at the 2009 SPD Meeting in Boulder, CO, and compare them and computed X-ray spectra with numerical results obtained by Zharkova & Gordovskii (2005, 2006). The phYSical significance of similarities and differences in the results will be emphasized. This work is supported by NASA's Heliophysics Guest Investigator Program and the RHESSI Project.

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    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.

  14. Variation in dental wear and tooth loss among known-aged, older ring-tailed lemurs (Lemur catta): a comparison between wild and captive individuals.

    PubMed

    Cuozzo, Frank P; Sauther, Michelle L; Gould, Lisa; Sussman, Robert W; Villers, Lynne M; Lent, Cheryl

    2010-11-01

    Tooth wear is generally an age-related phenomenon, often assumed to occur at similar rates within populations of primates and other mammals, and has been suggested as a correlate of reduced offspring survival among wild lemurs. Few long-term wild studies have combined detailed study of primate behavior and ecology with dental analyses. Here, we present data on dental wear and tooth loss in older (>10 years old) wild and captive ring-tailed lemurs (Lemur catta). Among older ring-tailed lemurs at the Beza Mahafaly Special Reserve (BMSR), Madagascar (n=6), the percentage of severe dental wear and tooth loss ranges from 6 to 50%. Among these six individuals, the oldest (19 years old) exhibits the second lowest frequency of tooth loss (14%). The majority of captive lemurs at the Indianapolis Zoo (n=7) are older than the oldest BMSR lemur, yet display significantly less overall tooth wear for 19 of 36 tooth positions, with only two individuals exhibiting antemortem tooth loss. Among the captive lemurs, only one lemur (a nearly 29 year old male) has lost more than one tooth. This individual is only missing anterior teeth, in contrast to lemurs at BMSR, where the majority of lost teeth are postcanine teeth associated with processing specific fallback foods. Postcanine teeth also show significantly more overall wear at BMSR than in the captive sample. At BMSR, degree of severe wear and tooth loss varies in same aged, older individuals, likely reflecting differences in microhabitat, and thus the availability and use of different foods. This pattern becomes apparent before "old age," as seen in individuals as young as 7 years. Among the four "older" female lemurs at BMSR, severe wear and/or tooth loss do not predict offspring survival. PMID:20872788

  15. Design and performance of a beam line with a 1 m focal length toroidal grating monochromator at the ACO storage ring

    NASA Astrophysics Data System (ADS)

    Gudat, W.; Kisker, E.; Rothberg, G. M.; Depautex, C.

    We describe a new beam line at the ACO storage ring for solid state photoelectron spectorscopy incorporating a 1 m focal length toroidal grating monochromator for the photon energy range 6 eV to 120 eV custom-built by Jobin-Yvon Instruments S.A. Test results for the TGM with laboratory line light sources are reported as well as performance data with synchrotron radiation.

  16. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Polarisation splitting of laser beams by large angles with minimal reflection losses

    NASA Astrophysics Data System (ADS)

    Davydov, B. L.

    2006-05-01

    New crystal anisotropic prisms for splitting orthogonally polarised components of laser radiation by large angles with minimal reflection losses caused by the Brewster refraction and total internal reflection of polarised waves from the crystal—air interface are considered and the method for their calculation is described. It is shown that, by assembling glue-free combinations of two or three prisms, thermally stable beamsplitters can be fabricated, which are free from the beam astigmatism and the wave dispersion of the output angles of the beams. The parameters and properties of new beamsplitters are presented in a convenient form in figures and tables.

  17. High performance quantum cascade lasers: Loss, beam stability, and gain engineering

    NASA Astrophysics Data System (ADS)

    Bouzi, Pierre Michel

    Quantum Cascade (QC) lasers are semiconductor devices emitting in the mid-infrared (3-30 micron) and terahertz (30-300 micron) regions of the electromagnetic spectrum. Since their first demonstration by Jerome Faist et. al. in 1994, they have evolved very quickly into high performance devices and given rise to many applications such as trace-gas sensing, medical diagnosis, free-space communication, and light detection and ranging (LIDAR). In this thesis, we investigate a further increase of the performance of QC devices and, through meticulous device modeling and characterizations, gain a deeper understanding of several of their unique characteristics, especially their carrier transport and lifetime, their characteristic temperature, their waveguide loss and modal gain, their leakage current, and their transverse mode profile. First, in our quest to achieve higher performance, we investigate the effect of growth asymmetries on device transport characteristics. This investigation stems from recent studies on the role of interface roughness on intersubband scattering and device performance. Through a symmetric active core design, we find that interface roughness and ionized impurity scattering induced by dopant migration play a significant role in carrier transport through the device. Understanding how interface roughness affects intersubband scattering, in turn, we engineer the gain in QC devices by placing monolayer barriers at specific locations within the device band structure. These strategically placed additional thin barrier layers introduce roughness scattering into the device active region, thereby selectively decreasing the lower laser state lifetime and increasing population inversion necessary for laser action. Preliminary measurement results from modified devices reveal a 50% decrease in the emission broadening compared to the control structures, which should lead to a two-fold increase in gain. A special class of so-called "strong coupling" QC lasers

  18. BEAM HALO FORMATION IN HIGH-INTENSITY BEAMS.

    SciTech Connect

    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.

  19. An ultra-compact and low loss passive beam-forming network integrated on chip with off chip linear array

    SciTech Connect

    Lepkowski, Stefan Mark

    2015-05-01

    The work here presents a review of beam forming architectures. As an example, the author presents an 8x8 Butler Matrix passive beam forming network including the schematic, design/modeling, operation, and simulated results. The limiting factor in traditional beam formers has been the large size dictated by transmission line based couplers. By replacing these couplers with transformer-based couplers, the matrix size is reduced substantially allowing for on chip compact integration. In the example presented, the core area, including the antenna crossover, measures 0.82mm×0.39mm (0.48% the size of a branch line coupler at the same frequency). The simulated beam forming achieves a peak PNR of 17.1 dB and 15dB from 57 to 63GHz. At the 60GHz center frequency the average insertion loss is simulated to be 3.26dB. The 8x8 Butler Matrix feeds into an 8-element antenna array to show the array patterns with single beam and adjacent beam isolation.

  20. DEVELOPMENT OF A HYDROGEN AND DEUTERIUM POLARIZED GAS TARGET FOR APPLICATION IN STORAGE RINGS

    SciTech Connect

    Willy Haeberli

    2009-06-18

    The exploration of spin degrees of freedom in nuclear and high-energy interactions requires the use of spin-polarized projectiles and/or spin-polarized targets. During the last two decades, the use of external beams from cyclotrons has to a large extent been supplanted by use of circulating beams stored in storage rings. In these experiments, the circulating particles pass millions of times through targets internal to the ring. Thus the targets need to be very thin to avoid beam loss by scattering out of the acceptance aperture of the ring.

  1. Energy Loss of a High Charge Bunched Electron Beam in Plasma: Nonlinear Plasma Response and Linear Scaling

    NASA Astrophysics Data System (ADS)

    Rosenzweig, J. B.; Barov, N.; Thompson, M. C.; Yoder, R.

    2002-12-01

    There has been much experimental and theoretical interest in blowout regime of plasma wakefield acceleration (PWFA), which features ultra-high accelerating fields, linear transverse focusing forces, and nonlinear plasma motion. Using an exact analysis, we examine here a fundamental limit of nonlinear PWFA excitation, by an infinitesimally short, relativistic electron beam. The beam energy loss in this case is shown to be linear in charge even for nonlinear plasma response, where a normalized, unitless charge exceeds unity, and relativistic plasma effects become important or dominant. The physical bases for this persistence of linear response are pointed out. As a byproduct of our analysis, we re-examine the issue of field divergence as the point-charge limit is approached, suggesting an important modification of commonly held views of evading unphysical energy loss. Deviations from linear behavior are investigated using simulations with finite length beams. The peak accelerating field in the plasma wave excited behind a 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 well into the nonlinear regime. On the other hand, at large enough normalized charge, linear scaling of fields collapses, with serious consequences for plasma wave excitation efficiency. The dramatic implications of these results for observing the collapse of linear scaling in planned experiments are discussed.

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

    SciTech Connect

    Wu, Jinyuan; Warner, Arden; /Fermilab

    2011-11-01

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

  3. Damping Ring R&D at CESR-TA

    SciTech Connect

    Rubin, David

    2015-01-23

    Accelerators that collide high energy beams of matter and anti-matter are essential tools for the investigation of the fundamental constituents of matter, and the search for new forms of matter and energy. A “Linear Collider” is a machine that would bring high energy and very compact bunches of electrons and positrons (anti-electrons) into head-on collision. Such a machine would produce (among many other things) the newly discovered Higgs particle, enabling a detailed study of its properties. Among the most critical and challenging components of a linear collider are the damping rings that produce the very compact and intense beams of electrons and positrons that are to be accelerated into collision. Hot dilute particle beams are injected into the damping rings, where they are compressed and cooled. The size of the positron beam must be reduced more than a thousand fold in the damping ring, and this compression must be accomplished in a fraction of a second. The cold compact beams are then extracted from the damping ring and accelerated into collision at high energy. The proposed International Linear Collider (ILC), would require damping rings that routinely produce such cold, compact and intense beams. The goal of the Cornell study was a credible design for the damping rings for the ILC. Among the technical challenges of the damping rings; the development of instrumentation that can measure the properties of the very small beams in a very narrow window of time, and mitigation of the forces that can destabilize the beams and prevent adequate cooling, or worse lead to beam loss. One of the most pernicious destabilizing forces is due to the formation of clouds of electrons in the beam pipe. The electron cloud effect is a phenomenon in particle accelerators in which a high density of low energy electrons, build up inside the vacuum chamber. At the outset of the study, it was anticipated that electron cloud effects would limit the intensity of the positron ring

  4. Collimation with hollow electron beams.

    PubMed

    Stancari, G; Valishev, A; Annala, G; Kuznetsov, G; Shiltsev, V; Still, D A; Vorobiev, L G

    2011-08-19

    A novel concept of controlled halo removal for intense high-energy beams in storage rings and colliders is presented. It is based on the interaction of the circulating beam with a 5-keV, magnetically confined, pulsed hollow electron beam in a 2-m-long section of the ring. The electrons enclose the circulating beam, kicking halo particles transversely and leaving the beam core unperturbed. By acting as a tunable diffusion enhancer and not as a hard aperture limitation, the hollow electron beam collimator extends conventional collimation systems beyond the intensity limits imposed by tolerable losses. The concept was tested experimentally at the Fermilab Tevatron proton-antiproton collider. The first results on the collimation of 980-GeV antiprotons are presented. PMID:21929171

  5. Properties of a laser cavity containing an absorbing ring.

    PubMed

    Hasnaoui, Abdelkrim; Ait-Ameur, Kamel

    2010-07-20

    This paper considers the transverse optical properties of an absorbing ring when it is lighted by a symmetrical Laguerre-Gauss beam TEM(p0). It is demonstrated that the insertion of an opaque ring having adequate size inside a diaphragmed laser cavity is able to improve greatly (rate of about 100%) the discrimination between the TEM(00) and the TEM(10) modes, while keeping the diffraction losses unchanged or even decreased. PMID:20648186

  6. Energy Loss of High Intensity Focused Proton Beams Penetrating Metal Foils

    NASA Astrophysics Data System (ADS)

    McGuffey, C.; Qiao, B.; Kim, J.; Beg, F. N.; Wei, M. S.; Evans, M.; Fitzsimmons, P.; Stephens, R. B.; Chen, S. N.; Fuchs, J.; Nilson, P. M.; Canning, D.; Mastrosimone, D.; Foord, M. E.

    2014-10-01

    Shortpulse-laser-driven intense ion beams are appealing for applications in probing and creating high energy density plasmas. Such a beam isochorically heats and rapidly ionizes any target it enters into warm dense matter with uncertain transport and stopping properties. Here we present experimental measurements taken with the 1.25 kJ, 10 ps OMEGA EP BL shortpulse laser of the proton and carbon spectra after passing through metal foils. The laser irradiated spherically curved C targets with intensity 4×1018 W/cm2, producing proton beams with 3 MeV slope temperature and a sharp low energy cutoff at 5 MeV which has not been observed on lower energy, shorter pulse intense lasers. The beam either diverged freely or was focused to estimated 1016 p +/cm2 ps by a surrounding structure before entering the metal foils (Al or Ag and a Cu tracer layer). The proton and ion spectra were altered by the foil depending on material and whether or not the beam was focused. Transverse proton radiography probed the target with ps temporal and 10 micron spatial resolution, indicating an electrostatic field on the foil may also have affected the beam. We present complementary particle-in-cell simulations of the beam generation and transport to the foils. This work was supported by the DOE/NNSA National Laser User Facility program, Contract DE-SC0001265.

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

    PubMed

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

    2013-06-01

    Pesticide sprayed onto crop leaves tends to be washed off by rainwater and discharge into the environment through leaching and runoff, resulting in severe pollution to both soil and water. Here, to control pesticide loss, we developed a loss-control pesticide (LCP) by adding modified natural nanoclay (diatomite) through high-energy electron beam (HEEB) to traditional pesticide. After HEEB treatment, the originally clogged pores in diatomite opened, resulting in plenty of micro-nanopores in diatomite, which are beneficial for the pesticide molecules to access and be adsorbed. This pesticide-diatomite complex tended to be retained by the rough surface of crop leaves, displaying a high adhesion performance onto the leaves, so that the pesticide loss reduced, sufficient pesticide for crops was supplied, and the pollution risk of the pesticide could be substantially lowered. PMID:23672373

  8. Ion Rings for Magnetic Fusion

    SciTech Connect

    Greenly, John, B.

    2005-07-31

    This Final Technical Report presents the results of the program, Ion Rings for Magnetic Fusion, which was carried out under Department of Energy funding during the period August, 1993 to January, 2005. The central objective of the program was to study the properties of field-reversed configurations formed by ion rings. In order to reach this objective, our experimental program, called the Field-reversed Ion Ring Experiment, FIREX, undertook to develop an efficient, economical technology for the production of field-reversed ion rings. A field-reversed configuration (FRC) in which the azimuthal (field-reversing) current is carried by ions with gyro-radius comparable to the magnetic separatrix radius is called a field-reversed ion ring. A background plasma is required for charge neutralization of the ring, and this plasma will be confined within the ring's closed magnetic flux. Ion rings have long been of interest as the basis of compact magnetic fusion reactors, as the basis for a high-power accelerator for an inertial fusion driver, and for other applications of high power ion beams or plasmas of high energy density. Specifically, the FIREX program was intended to address the longstanding question of the contribution of large-orbit ions to the observed stability of experimental FRCs to the MHD tilt mode. Typical experimental FRCs with s {approx} 2-4, where s is the ratio of separatrix radius to ion gyro-radius, have been stable to tilting, but desired values for a fusion reactor, s > 20, should be unstable. The FIREX ring would consist of a plasma with large s for the background ions, but with s {approx} 1 for the ring ions. By varying the proportions of these two populations, the minimum proportion of large-orbit ions necessary for stability could be determined. The incorporation of large-orbit ions, perhaps by neutral-beam injection, into an FRC has been advanced for the purpose of stabilizing, heating, controlling angular momentum, and aiding the formation of a

  9. Phase-space measurement of stored electron beam at the Cornell Electron Storage Ring using a combination of slit array and CCD detector

    SciTech Connect

    Cai, Z.; Lai, B.; Yun, W.; Gluskin, E.; Dejus, R.; Ilinski, P. )

    1995-02-01

    A new technique for fast phase-space measurement has been developed and tested during a recent APS/CHESS undulator run. A measurement time of a few seconds was obtained by using a slit array and a high-resolution position sensitive detector system. The detector system consists of a CdWO[sub 4] scintillation crystal, an optical imaging system, and a CCD detector. The short measurement time increases the measurement accuracy by reducing the effects from the instabilities of the electron beam in storage ring. The vertical emittance at the Cornell Electron Storage Ring in single-bunch and low-current mode was measured, and reasonable agreement with the expected values for both source size and source divergence were obtained ([sigma][sub [ital y

  10. Beam Halo formation and loss induced by image-charge effects in a small-aperture alternating-gradient focusing system

    SciTech Connect

    Zhou, J.; Qian, B.L.; Chen, C.; Henestroza, E.; Eylon, S.; Yu S.

    2003-05-01

    Effects of image charges on beam halo formation and beam loss in small-aperture alternating-gradient focusing systems are studied analytically, computationally, and experimentally. Nonlinear image-charge fields result in chaotic particle motion and the ejection of particles from the beam core into a halo. Detailed chaotic particle motion and structure of the particle phase space is studied, and the beam loss rate is computed for a long transport channel. Image-charge effects are also studied for a short transport channel, and compared with the Neutralized Transport Experiment (NTX) at LBNL.

  11. Measurements of the Propagation of EM Waves through the Vacuum Chamber of the PEP-II Low Energy Ring for Beam Diagnostics

    SciTech Connect

    Byrd, John Michael; De Santis, S.; Pivi, MTF; /SLAC

    2008-01-23

    We present the results of our measurements of the electron cloud density in the PEP-II low energy ring (LER) by propagating a TE wave into the beam pipe. By connecting a signal generator to a beam position monitor button we can excite a signal above the vacuum chamber cut-off frequency and measure its propagation through the beam pipe with a spectrum analyzer connected to another button about 50 meters away. The measurement can be performed with different beam conditions and also at different settings of the solenoids used to reduce the build up of electrons. The presence of a modulation in the TE wave transmission, synchronous with the beam revolution frequency, which appear to increase in depth when the solenoids are switched off, seem to be directly correlated to the electron cloud density in the region between the two BPM's. In this paper we present and discuss the measurements taken in the Interaction Region 12 straight of the LER during 2006 and the first part of 2007.

  12. Ring cusp/hollow cathode discharge chamber performance studies

    NASA Technical Reports Server (NTRS)

    Vaughn, J. A.; Wilbur, P. J.

    1988-01-01

    An experimental study performed to determine the effects of hollow cathode position, anode position, and ring cusp magnetic field configuration and strength on discharge chamber performance is described. The results are presented in terms of comparative plasma ion energy cost, extracted ion fraction, and beam profile data. Results show that the rate of primary electron loss to the anode decreases as the anode is moved downstream of the ring cusp toward the screen grid and that the loss rate of ions to hollow cathode surfaces are excessive if the cathode is located upstream of a point of peak magnetic flux density at the discharge chamber centerline. Moreover, the fraction of the ions produced that are lost to discharge chamber walls and ring magnet surfaces is reduced by positioning of the magnet rings so the plasma density is uniform over the grid surface, and adjusting their strength to a level where it is sufficient to prevent excessive ion losses by Bohm diffusion.

  13. Ring energy and current considerations for spallation neutron source

    SciTech Connect

    Blumberg, L.N.

    1994-04-01

    The most desirable energy E{sub o} of protons from the synchrotron and thus beam current {bar I} to produced a given beam power P{sub B} involves a balanced consideration of neutron production capability, accelerator beam stability, user requirements, and cost considerations. The present solution consists of two 3.6-GeV rings with a 600-MeV Linac injector, a compromise between conflicting factors of cost and technical concern. The authors believe that the design is a conservative one. They could increase the beam energy and/or the repetition rate and thereby decrease the requirement for the number of protons N{sub o} in the ring which in the present design is an extrapolation of about a factor of 7 from existing ring intensities. However, the specified ring acceptance appears quite adequate to contain the required 1.45 10{sup 14} protons/ring and the resulting loss in the target window and target are reasonable. The beam power and current are indeed modest in terms of window and target integrity compared to the 200 MW, 200mA 1-GeV design for the APT. The two-ring approach also offers several practical advantages -- the project is stageable in the sense that only one ring may be required initially to achieve P{sub B} = 2.5 MW power on the target with subsequent expansion to 5 MW with addition of the second ring. Two rings also provide additional reliability in the sense that the user program need not be interrupted by failure of one ring.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  15. Higher-order modes of storage ring rf cavities and their interaction with the beam at the Advanced Photon Source (APS)

    SciTech Connect

    Song, J.J.; Harkay, K.C.; Kang, Y.W.

    1997-09-01

    The higher-order modes (HOMs) of APS storage ring (SR) rf cavities and waveguides were measured under various operating conditions. The HOMs of the 352-MHz rf cavity can be one of the major contributors to the coupled bunch (CB) instability. The distribution of HOMs under various conditions of beam current, cavity temperature, cavity tuning, single-bunch and multi-bunch operation, and fill patterns, are presented. The HOMs` shunt impedance of the loaded cavities were also measured. The effect of stagger tuning of the 16 cavities and their waveguide system is compared, and the HOM dampers are examined.

  16. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry

    2014-03-01

    Preface: a personal view of planetary rings; 1. Introduction: the allure of the ringed planets; 2. Studies of planetary rings 1610-2013; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Uranus' rings and moons; 13. Neptune's partial rings; 14. Jupiter's ring-moon system after Galileo and New Horizons; 15. Ring photometry; 16. Dusty rings; 17. Concluding remarks; Afterword; Glossary; References; Index.

  17. Radical-induced dissociation leading to the loss of CO2 from the oxazolone ring of [b5- H]˙(+) ions.

    PubMed

    Lau, Justin Kai-Chi; Zhao, Junfang; Williams, Declan; Wu, Bai-Han Backen; Wang, Yating; Mädler, Stefanie; Saminathan, Irine S; Siu, K W Michael; Hopkinson, Alan C

    2016-07-21

    Macrocyclization is commonly observed in large bn(+) (n≥ 4) ions and as a consequence can lead to incorrect protein identification due to sequence scrambling. In this work, the analogous [b5- H]˙(+) radical cations derived from aliphatic hexapeptides (GA5˙(+)) also showed evidence of macrocyclization under CID conditions. However, the major fragmentation for [b5- H]˙(+) ions is the loss of CO2 and not CO loss, which is commonly observed in closed-shell bn(+) ions. Isotopic labeling using CD3 and (18)O revealed that more than one common structure underwent dissociations. Theoretical studies found that the loss of CO2 is radical-driven and is facilitated by the radical being located at the Cα atom immediately adjacent to the oxazolone ring. Comparable energy barriers against macrocyclization, hydrogen-atom transfer, and fragmentations are found by DFT calculations and the results are consistent with the experimental observations that a variety of dissociation products are observed in the CID spectra. PMID:27327880

  18. Resistive-wall instability at Fermilab recycler ring

    SciTech Connect

    Ng, King-Yuen B.; /Fermilab

    2004-11-01

    Sporadic transverse instabilities have been observed at the Fermilab Recycler Ring leading to increase in transverse emittances and beam loss. The driving source of these instabilities has been attributed to the resistive-wall impedance with space-charge playing an important role in suppressing Landau damping. Growth rates of the instabilities have been computed. Remaining problems are discussed.

  19. Station for X-ray structural analysis of materials and single crystals (including nanocrystals) on a synchrotron radiation beam from the wiggler at the Siberia-2 storage ring

    SciTech Connect

    Kheiker, D. M. Kovalchuk, M. V.; Korchuganov, V. N.; Shilin, Yu. N.; Shishkov, V. A.; Sulyanov, S. N.; Dorovatovskii, P. V.; Rubinsky, S. V.; Rusakov, A. A.

    2007-11-15

    The design of the station for structural analysis of polycrystalline materials and single crystals (including nanoobjects and macromolecular crystals) on a synchrotron radiation beam from the superconducting wiggler of the Siberia-2 storage ring is described. The wiggler is constructed at the Budker Institute of Nuclear Physics of the Siberian Division of the Russian Academy of Sciences. The X-ray optical scheme of the station involves a (1, -1) double-crystal monochromator with a fixed position of the monochromatic beam and a sagittal bending of the second crystal, segmented mirrors bent by piezoelectric motors, and a (2{theta}, {omega}, {phi}) three-circle goniometer with a fixed tilt angle. Almost all devices of the station are designed and fabricated at the Shubnikov Institute of Crystallography of the Russian Academy of Sciences. The Bruker APEX11 two-dimensional CCD detector will serve as a detector in the station.

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

    PubMed

    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. PMID:24690859

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

    SciTech Connect

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

    1995-10-12

    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{sup {minus}3}, 10{sup {minus}4} and 10{sup {minus}5} torr).

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

    SciTech Connect

    Powell, A.; Szekely, J.; Avyle, J.V.D.; Damkroger, B.

    1995-12-31

    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 (10{sup {minus}3}, 10{sup {minus}4} and 10{sup {minus}5} torr).

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

    SciTech Connect

    Hamm, L.L.

    1998-10-07

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

  4. Analytic expressions for the inelastic scattering and energy loss of electron and proton beams in carbon nanotubes

    SciTech Connect

    Emfietzoglou, D.; Kyriakou, I.; Garcia-Molina, R.; Abril, I.; Kostarelos, K.

    2010-09-15

    We have determined ''effective'' Bethe coefficients and the mean excitation energy of stopping theory (I-value) for multiwalled carbon nanotubes (MWCNTs) and single-walled carbon nanotube (SWCNT) bundles based on a sum-rule constrained optical-data model energy loss function with improved asymptotic properties. Noticeable differences between MWCNTs, SWCNT bundles, and the three allotropes of carbon (diamond, graphite, glassy carbon) are found. By means of Bethe's asymptotic approximation, the inelastic scattering cross section, the electronic stopping power, and the average energy transfer to target electrons in a single inelastic collision, are calculated analytically for a broad range of electron and proton beam energies using realistic excitation parameters.

  5. Analytic expressions for the inelastic scattering and energy loss of electron and proton beams in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Emfietzoglou, D.; Kyriakou, I.; Garcia-Molina, R.; Abril, I.; Kostarelos, K.

    2010-09-01

    We have determined "effective" Bethe coefficients and the mean excitation energy of stopping theory (I-value) for multiwalled carbon nanotubes (MWCNTs) and single-walled carbon nanotube (SWCNT) bundles based on a sum-rule constrained optical-data model energy loss function with improved asymptotic properties. Noticeable differences between MWCNTs, SWCNT bundles, and the three allotropes of carbon (diamond, graphite, glassy carbon) are found. By means of Bethe's asymptotic approximation, the inelastic scattering cross section, the electronic stopping power, and the average energy transfer to target electrons in a single inelastic collision, are calculated analytically for a broad range of electron and proton beam energies using realistic excitation parameters.

  6. Status report on the Los Alamos proton storage ring

    SciTech Connect

    Colton, E.; Neuffer, D.; Thiessen, H.A.; Butler, H.; Swain, G.R.; Lombardi, A.; Fitzgerald, D.; Mariam, F.; Plum, M.; Ryder, R.; and others

    1988-11-20

    The proton storage ring currently operates at an average current of 30 ..mu..A corresponding to 1.25 x 10/sup 13/ protons per pulse (ppp) at a repetition rate of 15 Hz. The design operating current for the machine is 100 ..mu..A. We are limited to running at the reduced yield because of beam losses during the accumulation period. These losses are understood and arise mainly from emittance growths during the injection and multiple scattering in the stripping foil during the storage. During beam studies we have succeeded in accumulating in excess of 3.7 x 10/sup 13/ ppp. We have also observed a coherent transverse instability at high charge levels. The signture for the instability is rapid coherent growth of the transverse beam size followed by a loss of beam in the machine. The threshold for the instability depends most strongly upon rf voltage and beam size.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

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

    SciTech Connect

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

    2009-08-01

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

  9. Rapid screening of illicit additives in weight loss dietary supplements with desorption corona beam ionisation (DCBI) mass spectrometry.

    PubMed

    Wang, H; Wu, Y; Zhao, Y; Sun, W; Ding, L; Guo, B; Chen, B

    2012-08-01

    Desorption corona beam ionisation (DCBI), the relatively novel ambient mass spectrometry (MS) technique, was utilised to screen for illicit additives in weight-loss food. The five usually abused chemicals - fenfluramine, N-di-desmethyl sibutramine, N-mono-desmethyl sibutramine, sibutramine and phenolphthalein - were detected with the proposed DCBI-MS method. Fast single-sample and high-throughput analysis was demonstrated. Semi-quantification was accomplished based on peak areas in the ion chromatograms. Four illicit additives were identified and semi-quantified in commercial samples. As there was no tedious sample pre-treatment compared with conventional HPLC methods, high-throughput analysis was achieved with DCBI. The results proved that DCBI-MS is a powerful tool for the rapid screening of illicit additives in weight-loss dietary supplements. PMID:22784191

  10. Overview of collective effects in the NLC main damping rings

    SciTech Connect

    Wolski, A.; de Santis, S.

    2002-05-30

    The present design for the NLC Main Damping Rings (MDRs) meets the specifications for acceptance and extracted emittance, in the limit of zero current. However, the relatively large bunch charge and moderate energy mean that a variety of collective effects can impact the beam dynamics, leading to loss of stability or increase of equilibrium emittance. These effects include intrabeam scattering, impedance from numerous sources, fast ion instability, and (in the positron ring) electron cloud. In this note, we survey the expected impact on damping ring performance from each of a number of collective effects, and discuss the priorities for future studies in this area.

  11. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.

    2011-07-01

    Preface; 1. Introduction: the allure of ringed planets; 2. Studies of planetary rings 1610-2004; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-Body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Neptune's partial rings; 13. Jupiter's ring-moon system after Galileo; 14. Ring photometry; 15. Dusty rings; 16. Cassini observations; 17. Summary: the big questions; Glossary; References; Index.

  12. Updated analytical solutions of continuity equation for electron beams precipitation - I. Pure collisional and pure ohmic energy losses

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    We present updated analytical solutions of continuity equations for power-law beam electrons precipitating in (a) purely collisional losses and (b) purely ohmic losses. The solutions of continuity equation (CE) normalized on electron density presented in Dobranskis & Zharkova are found by method of characteristics eliminating a mistake in the density characteristic pointed out by Emslie et al. The corrected electron beam differential densities (DD) for collisions are shown to have energy spectra with the index of -(γ + 1)/2, coinciding with the one derived from the inverse problem solution by Brown, while being lower by 1/2 than the index of -γ/2 obtained from CE for electron flux. This leads to a decrease of the index of mean electron spectra from -(γ - 2.5) (CE for flux) to -(γ - 2.0) (CE for electron density). The similar method is applied to CE for electrons precipitating in electric field induced by the beam itself. For the first time, the electron energy spectra are calculated for both constant and variable electric fields by using CE for electron density. We derive electron DD for precipitating electrons (moving towards the photosphere, μ = +1) and `returning' electrons (moving towards the corona, μ = -1). The indices of DD energy spectra are reduced from -γ - 1 (CE for flux) to -γ (CE for electron density). While the index of mean electron spectra is increased by 0.5, from -γ + 0.5 (CE for flux) to -γ + 1(CE for electron density). Hard X-ray intensities are also calculated for relativistic cross-section for the updated differential spectra revealing closer resemblance to numerical Fokker-Planck (FP) solutions.

  13. Using a double-frequency RF system to facilitate on-axis beam accumulation in a storage ring

    NASA Astrophysics Data System (ADS)

    Jiang, B. C.; Zhao, Z. T.; Tian, S. Q.; Zhang, M. Z.; Zhang, Q. L.

    2016-04-01

    An on-axis injection scheme using a double-frequency RF system in a storage ring with small dynamic aperture is proposed. By altering RF voltages, empty RF buckets can be created which will be used for on-axis injection. After bunches are injected, a reverse RF voltage altering process is performed and the injected bunches can be longitudinally dumped to the main RF buckets. The scheme allows reaping the advantages of the on-axis injection while still performing accumulation.

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

    NASA Astrophysics Data System (ADS)

    Hotchi, Hideaki; Tani, Norio; Watanabe, Yasuhiro

    2015-04-01

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

  15. The proton storage ring: Problems and solutions

    SciTech Connect

    Macek, R.J.

    1988-01-01

    The Los Alamos Proton Storage Ring (PSR) now operates with 35..mu..A at 20-Hz pulse repetition rate. Beam availability during 1988 suffered because of a number of problems with hardware reliability and from narrow operating margins for beam spill in the extraction line. A strong effort is underway to improve reliability with an eventual goal of obtaining beam availability in excess of 75%. Beam losses and the resulting component activation have limited operating currents to their present values. In detailed studies of the problem, loss rates were found to be approximately proportional to the circulating current and can be understood by a detailed accounting of emittance growth in the two-step injection process along with Coulomb scattering of the stored beam during multiple traversals of the injection foil. It is now apparent that the key to reducing losses is in reducing the number of foil traversals. A program of upgrades to reduce losses and improve the operating current is being planned. 8 refs., 17 figs., 2 tabs.

  16. Comparative study on the separation behavior of monolithic columns prepared via ring-opening metathesis polymerization and via electron beam irradiation triggered free radical polymerization for proteins.

    PubMed

    Bandari, Rajendar; Knolle, Wolfgang; Buchmeiser, Michael R

    2008-05-16

    Monolithic columns have been prepared via ring-opening metathesis polymerization using different monomers and crosslinkers, i.e. norborn-2-ene, 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo,endo-dimethanonaphthalene, cyclooctene and tris(cyclooct-4-en-1-yloxy)methylsilane. 2-Propanol and toluene were used as macro- and microporogens. Alternatively, monolithic supports were realized via electron beam triggered free radical polymerization using trimethylolpropane triacrylate and ethylmethacrylate. Here, 2-propanol, 1-dodecanol and toluene were used as porogens. The three monolithic supports were structurally characterized by inverse size exclusion chromatography and investigated for their separation capabilities for a series of proteins. Separation efficiencies are discussed within the context of the different structural features of the monolithic supports and are compared to the separation data obtained on a commercial silica-based Chromolith RP-18e column. PMID:18037426

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

    NASA Astrophysics Data System (ADS)

    Tsoupas, N.; Huang, H.; MacKay, W. W.; Meot, F.; Roser, T.; Trbojevic, D.

    2013-04-01

    The principle of using multiple partial helical magnets to preserve the polarization of the proton beam during its acceleration was applied successfully to the alternating gradient synchrotron (AGS) which currently operates with two partial helical magnets. In this paper we further explore this idea by using four partial helical magnets placed symmetrically in the AGS ring. This provides many advantages over the present setup of the AGS, which uses two partial helical magnets. First, the symmetric placement of the four helical magnets and their relatively lower field of operation allows for better control of the AGS optics with reduced values of the beta functions especially near beam injection and allows both the vertical and horizontal tunes to be placed within the “spin tune gap,” therefore eliminating the horizontal and vertical intrinsic spin resonances of the AGS during the acceleration cycle. Second, it provides a wider spin tune gap. Third, the vertical spin direction during beam injection and extraction is closer to vertical. Although the spin tune gap, which is created with four partial helices, can also be created with a single or two partial helices, the high field strength of a single helical magnet which is required to generate such a spin tune gap makes the use of the single helical magnet impractical, and that of the two helical magnets rather difficult. In this paper we will provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and compare them with those from the present setup of the AGS that uses two partial helical magnets. Although in this paper we specifically discuss the effect of the four partial helices on the AGS, this method which can eliminate simultaneously the vertical and horizontal intrinsic spin resonances is a general method and can be applied to any medium energy synchrotron which operates in similar energy range like the AGS and provides the required space to accommodate the four

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

    SciTech Connect

    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.

  19. CONSTRUCTION STATUS AND ISSUES OF THE SPALLATION NEUTRON SOURCE RING.

    SciTech Connect

    WEI,J.

    2004-07-05

    The Spallation Neutron Source (SNS) ring is designed to accumulate beam pulses of 1.5 x 10{sup 14} protons of 1 GeV kinetic energy at a repetition rate of 60 Hz [1]. At such beam intensity and power, key design challenges include control of beam loss and radio-activation, construction of high-quality large-aperture magnets and power supplies, design of robust injection and extraction systems, minimization of beam-coupling impedances, and mitigation of electron-cloud effects. This paper discusses the status of the ring systems with emphasis on technical challenges and issues, and presents future perspectives towards a next-generation high-intensity facility.

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

    SciTech Connect

    Thome, Lionel; Debelle, Aurelien; Garrido, Frederico; Trocellier, Patrick; Serruys, Yves; Miro, Sandrine

    2013-04-08

    Single and dual-beam irradiations of oxide (c-ZrO{sub 2}, MgO, Gd{sub 2}Ti{sub 2}O{sub 7}) and carbide (SiC) single crystals were performed to study combined effects of nuclear (S{sub n}) and electronic (S{sub e}) energy losses. Rutherford backscattering experiments in channeling conditions show that the S{sub n}/S{sub e} cooperation induces a strong decrease of the irradiation-induced damage in SiC and MgO and almost no effects in c-ZrO{sub 2} and Gd{sub 2}Ti{sub 2}O{sub 7}. The healing process is ascribed to electronic excitations arising from the electronic energy loss of swift ions. These results present a strong interest for both fundamental understanding of the ion-solid interactions and technological applications in the nuclear industry where expected cooperative S{sub n}/S{sub e} effects may lead to the preservation of the integrity of nuclear devices.

  1. Electron cloud simulations of a proton storage ring using cold proton bunches

    NASA Astrophysics Data System (ADS)

    Sato, Y.; Holmes, J.; Lee, S. Y.; Macek, R.

    2008-02-01

    Using the ORBIT code we study the sensitivity of electron cloud properties with respect to different proton beam profiles, the secondary electron yield (SEY) parameter, and the proton loss rate. Our model uses a cold proton bunch to generate primary electrons and electromagnetic field for electron cloud dynamics. We study the dependence of the prompt and swept electron signals vs the bunch charge and the recovery of electron clouds after sweeping on the beam loss rate and the SEY. The simulation results are compared with the experimental data measured at the proton storage ring at the Los Alamos National Laboratory. Our simulations indicate that the fractional proton loss rate in the field-free straight section may be an exponential function of proton beam charge and may also be lower than the averaged fractional proton loss rate over the whole ring.

  2. LATTICES FOR HIGH-POWER PROTON BEAM ACCELERATION AND SECONDARY BEAM COLLECTION AND COOLING.

    SciTech Connect

    WANG, S.; WEI, J.; BROWN, K.; GARDNER, C.; LEE, Y.Y.; LOWENSTEIN, D.; PEGGS, S.; SIMOS, N.

    2006-06-23

    Rapid cycling synchrotrons are used to accelerate high-intensity proton beams to energies of tens of GeV for secondary beam production. After primary beam collision with a target, the secondary beam can be collected, cooled, accelerated or decelerated by ancillary synchrotrons for various applications. In this paper, we first present a lattice for the main synchrotron. This lattice has: (a) flexible momentum compaction to avoid transition and to facilitate RF gymnastics (b) long straight sections for low-loss injection, extraction, and high-efficiency collimation (c) dispersion-free straights to avoid longitudinal-transverse coupling, and (d) momentum cleaning at locations of large dispersion with missing dipoles. Then, we present a lattice for a cooler ring for the secondary beam. The momentum compaction across half of this ring is near zero, while for the other half it is normal. Thus, bad mixing is minimized while good mixing is maintained for stochastic beam cooling.

  3. Simulations of high disruption colliding beams

    SciTech Connect

    Boyce, J.R.; Heifets, S.; Krafft, G.A.

    1990-09-01

    Recent B-factory proposals that use a linac beam colliding with the beam from a storage ring to achieve high luminosities (L > 10{sup 34} cm{sup {minus}2}sec{sup {minus}1}) result in very high disruption of the linac beam. The effects of such high disruption have been studied using the relativistic, 3-D code SWARM. We discuss the assumptions, parameters, and results of a series of runs that model such collisions. Regimes of high beam loss and methods to avoid them are also discussed. 5 refs., 4 figs.

  4. CONTINUOUS EXTRACTED BEAM IN THE AGS FAST EXTERNAL BEAM LINE.

    SciTech Connect

    GLENN,J.W.; TSOUPAS,N.; BROWN,K.A.; BIRYUKOV,V.M.

    2001-06-18

    A method to split off a few percent of the 6 x 10{sup 13} AGS beam delivered to the Slow External Beam (SEB) lines and send it down the Fast External Beam line (FEB) has been developed. The mission is to feed a counter experiment off the FEB that directly measures the neutrino mass using the muon storage ring. The use of normal thin septum splitters would have an excessive loss overhead and been optically difficult. The AGS Slow Extraction uses a third integer resonance with sextuple strength so the resonance width is a few percent of the beam width. This results in a low density tail which will be clipped by a bent crystal and deflected into the FEB channel. This clipping off of the tail should reduce losses in the SEB transport line. Details of modeled orbits, particle distribution and extraction trajectories into and out off the crystal will be given.

  5. THE CIRCULAR RFQ STORAGE RING

    SciTech Connect

    RUGGIERO,A.G.

    1998-10-20

    This paper presents a novel idea of storage ring for the accumulation of intense beams of light and heavy ions at low energy. The new concept is a natural development of the combined features used in a conventional storage ring and an ion trap, and is basically a linear RFQ bend on itself. In summary the advantages are: smaller beam dimensions, higher beam intensity, and a more compact storage device.

  6. Mars Express observations of high altitude planetary ion beams and their relation to the "energetic plume" loss channel

    NASA Astrophysics Data System (ADS)

    Liemohn, Michael W.; Johnson, Blake C.; Fränz, Markus; Barabash, Stas

    2014-12-01

    This study presents observational evidence of high-energy (ions >2 keV) beams of planetary ions above Mars' induced magnetospheric boundary (IMB) and relates them with the energetic plume loss channel calculated from numerical models. A systematic search of the Mars Express (MEX) ion data using an orbit filtering criteria is described, using magnetometer data from Mars Global Surveyor (MGS) to determine the solar wind motional electric field (Esw) direction. Two levels of statistical survey are presented, one focused on times when the MEX orbit was directly in line with the Esw and another for all angles between the MEX location and the Esw. For the first study, within the 3 year overlap of MGS and MEX, nine brief intervals were found with clear and unambiguous high-energy O+ observations consistent with the energetic plume loss channel. The second survey used a point-by-point determination of MEX relative to the E-field and contained many thousands of 192 s measurements. This study yielded only a weak indication for an Esw-aligned plume. Furthermore, the y-z components of the weighted average velocities in the bins of this y-z spatial domain survey do not systematically point in the Esw direction. The first survey implies the existence of this plume and shows that its characteristics are seemingly consistent with the expected energy and flight direction from numerical studies; the second study softens the finding and demonstrates that there are many planetary ions beyond the IMB moving in unexpected directions. Several possible explanations for this discrepancy are discussed.

  7. Planetary rings

    SciTech Connect

    Greenberg, R.; Brahic, A.

    1984-01-01

    Among the topics discussed are the development history of planetary ring research, the view of planetary rings in astronomy and cosmology over the period 1600-1900, the characteristics of the ring systems of Saturn and Uranus, the ethereal rings of Jupiter and Saturn, dust-magnetosphere interactions, the effects of radiation forces on dust particles, the collisional interactions and physical nature of ring particles, transport effects due to particle erosion mechanisms, and collision-induced transport processes in planetary rings. Also discussed are planetary ring waves, ring particle dynamics in resonances, the dynamics of narrow rings, the origin and evolution of planetary rings, the solar nebula and planetary disk, future studies of the planetary rings by space probes, ground-based observatories and earth-orbiting satellites, and unsolved problems in planetary ring dynamics.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  9. Washout rate in rat brain irradiated by a 11C beam after acetazolamide loading using a small single-ring OpenPET prototype

    NASA Astrophysics Data System (ADS)

    Hirano, Yoshiyuki; Takuwa, Hiroyuki; Yoshida, Eiji; Nishikido, Fumihiko; Nakajima, Yasunori; Wakizaka, Hidekatsu; Yamaya, Taiga

    2016-03-01

    In dose verification techniques of particle therapies based on in-beam positron emission tomography (PET), the causes of washout of positron emitters by physiological effects should be clarified to correct washout for accurate verification. As well, the quantitative washout rate has a potential usefulness as a diagnostic index which should be explored. Therefore, we measured washout rates of rat brain after vasodilator acetazolamide loading to investigate the possible effects of blood flow on washout. Six rat brains were irradiated by a radioisotope 11C beam and time activity curves on the whole brains were obtained with a small single-ring OpenPET prototype. Then, washout rates were calculated with the Mizuno model, where two washout rates (k 2m and k 2s ) were assumed, and a two-compartment model including efflux from tissue to blood (k 2) and influx (k 3) and efflux (k 4) between the two tissue compartments. Before the irradiations, we used laser-Doppler flowmetry to confirm that acetazolamide increased cerebral blood flow (CBF) of a rat. We compared means of k 2m , k 2s and k 2, k 3 and k 4 without acetazolamide loading (Rest) and with acetazolamide loading (ACZ). For all k values, ACZ values were lower than Rest values. In other words, though CBF increased, washout rates were decreased. This may be attributed to the implanted 11C reacting to form 11CO2. Because acetazolamide increased the concentration of CO2 in brain, suppressed diffusion of 11CO2 and decomposition of 11CO2 into ions were prevented.

  10. Report of the New Rings Study Group

    SciTech Connect

    Holmes, S.D.; Dugan, G.; Marriner, J.

    1987-10-19

    We have taken the approach here of trying to understand both the feasibility and practicality of varied options for new rings at Fermilab, rather than trying to produce a single detailed design. In other words, this document is not a design report and should not be construed as such. Our perception of the potential needs for new rings (in order of priority) is as follows: Antiproton Storage and/or Recovery: A facility for storing up to 4 x 10/sup 12/ antiprotons is needed. Recovery of antiprotons from the collider becomes a viable option if the luminosity is indeed dominated by emittance dilution rather than beam loss. New or Post-Booster: The goal here would be to inject into the existing Main Ring above transition. Improved performance of the Main Ring would be anticipated. New Main Ring: Advantages would include better emittance preservation, a faster cycle time for antiproton production, and the removal of interference/backgrounds at the B0 and D0 detectors. We discuss in this paper various scenarios based on one or more combinations of the above possibilities. 14 figs., 10 tabs.

  11. Saturn's rings

    NASA Technical Reports Server (NTRS)

    2000-01-01

    When seen from the unlit side, the rings of Saturn present a much different appearance from that familiar to telescopic observers. Relatively opaque areas like the B Ring turn black, while lightly populated zones, such as the C Ring and the Cassini Division, prove to excellent diffuse transmitters of sunlight. The A Ring, with intermediate opacity, is at an intermediate level of brightness.

  12. Recent Progress in a Beam-Beam Simulation Code for Circular Hadron Machines

    SciTech Connect

    Kabel, Andreas; Fischer, Wolfram; Sen, Tanaji; /Fermilab

    2007-09-10

    While conventional tracking codes can readily provide higher-order optical quantities and give an estimate of dynamic apertures, they are unable to provide directly measurable quantities such as lifetimes and loss rates. The particle tracking framework Plibb aims at modeling a storage ring with sufficient accuracy and a sufficiently high number of turns and in the presence of beam-beam interactions to allow for an estimate of these quantities. We provide a description of new features of the codes; we also describe a novel method of treating chromaticity in ring sections in a symplectic fashion.

  13. Reversible Seeding in Storage Rings

    SciTech Connect

    Ratner, Daniel; Chao, Alex; /SLAC

    2011-12-14

    We propose to generate steady-state microbunching in a storage ring with a reversible seeding scheme. High gain harmonic generation (HGHG) and echo-enabled harmonic generation (EEHG) are two promising methods for microbunching linac electron beams. Because both schemes increase the energy spread of the seeded beam, they cannot drive a coherent radiator turn-by-turn in a storage ring. However, reversing the seeding process following the radiator minimizes the impact on the electron beam and may allow coherent radiation at or near the storage ring repetition rate. In this paper we describe the general idea and outline a proof-of-principle experiment. Electron storage rings can drive high average power light sources, and free-electron lasers (FELs) are now producing coherent light sources of unprecedented peak brightness While there is active research towards high repetition rate FELs (for example, using energy recovery linacs), at present there are still no convenient accelerator-based sources of high repetition rate, coherent radiation. As an alternative avenue, we recently proposed to establish steady-state microbunching (SSMB) in a storage ring. By maintaining steady-state coherent microbunching at one point in the storage ring, the beam generates coherent radiation at or close to the repetition rate of the storage ring. In this paper, we propose a method of generating a microbunched beam in a storage ring by using reversible versions of linac seeding schemes.

  14. Quality factor and finesse optimization in buried InGaAsP/InP ring resonators

    NASA Astrophysics Data System (ADS)

    Ciminelli, C.; Passaro, V. M. N.; Dell'Olio, F.; Armenise, M. N.

    2009-06-01

    Quality factor and finesse of buried In1 xGaxAsyP1 y / InP ring resonators have been optimized in this paper by a very general modelling technique. Limiting effect of propagation loss within the ring has been investigated using a three-dimensional (3D) highly accurate complex mode solver based on mode matching method to analyze bending loss dependence on ring radius and wavelength. Coupling between straight input/output (I/O) bus waveguides and ring resonator has been studied by 3D Beam Propagation Method (BPM), deriving coupling loss and coupling coefficient for a large range of ring radius and bus waveguides-ring distance values (for both polarizations). Ring resonator has been modelled by the transfer-matrix approach, while finesse and quality factor dependence on radius has been estimated for two resonator architectures (including one or two I/O bus waveguides) and for quasi-TE and quasi-TM modes. Guiding structure has been optimized to enhance resonator performance. The modelling approach has been validated by comparing results obtained by our algorithm with experimental data reported in literature. Influence of rejection (at resonance wavelength) at through port on quality factor and finesse has been widely discussed. A quality factor larger than 8105 has been predicted for the ring resonator employing only one I/O bus waveguide and having a radius of 400 mm. This resonator exhibits a rejection of -8 dB at through port.

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

    SciTech Connect

    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.

  16. Cavity-locked ring down spectroscopy

    DOEpatents

    Zare, Richard N.; Paldus, Barbara A.; Harb, Charles C.; Spence, Thomas

    2000-01-01

    Distinct locking and sampling light beams are used in a cavity ring-down spectroscopy (CRDS) system to perform multiple ring-down measurements while the laser and ring-down cavity are continuously locked. The sampling and locking light beams have different frequencies, to ensure that the sampling and locking light are decoupled within the cavity. Preferably, the ring-down cavity is ring-shaped, the sampling light is s-polarized, and the locking light is p-polarized. Transmitted sampling light is used for ring-down measurements, while reflected locking light is used for locking in a Pound-Drever scheme.

  17. Observation of space-charge effects in the Los Alamos Proton Storage Ring

    SciTech Connect

    Neuffer, D.; Fitzgerald, D.; Hardek, T.; Hutson, R.; Macek, R.; Plum, M.; Thiessen, H.; Wang, T.S.

    1991-01-01

    In recent operation of the Los Alamos Proton Storage Ring (PSR), the vertical and horizontal tunes have been moved closer to the integers (v{sub y} = 2.12, v{sub x} = 3.17) due to enlarge the low-los working region. In this region, the beam can be significantly affected by space charge. The first observed effects are a nondestructive distortion of the beam profile and vertical growth of beam size sufficient to keep the shifted tunes from crossing the integer, but without large beam loss. At higher intensities, or with tunes closer to the integer, beam blow-up, accompanied by beam losses, can occur. In this paper, we report recent observations of this intensity-dependent effect and discuss implications for future PSR operation. 4 refs., 2 figs., 1 tab.

  18. HIGH INTENSITY EFFECTS IN THE SNS ACCUMULATOR RING

    SciTech Connect

    Holmes, Jeffrey A; Cousineau, Sarah M; Danilov, Viatcheslav; Plum, Michael A; Shishlo, Andrei P

    2008-01-01

    Currently operating at 0.5 MW beam power on target, the Spallation Neutron Source (SNS) is already the world's most powerful pulsed neutron source. However, we are only one third of the way to full power. As we ramp toward full power, the control of the beam and beam loss in the ring will be critical. In addition to practical considerations, such as choice of operating point, painting scheme, RF bunching, and beam scattering, it may be necessary to understand and mitigate collective effects due to space charge, impedances, and electron clouds. At each stage of the power ramp-up, we use all available resources to understand and to minimize beam losses. From the standpoint of beam dynamics, the losses observed so far under normal operating conditions have not involved collective phenomena. We are now entering the intensity regime in which this may change. In dedicated high intensity beam studies, we have already observed resistive wall, extraction kicker impedance-driven, and electron cloud activities. The analysis and simulation of this data are important ongoing activities at SNS. This paper discusses the status of this work, as well as other considerations necessary to the successful full power operation of SNS.

  19. Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Cuzzi, J. N.

    2014-12-01

    The rings are changing before our eyes; structure varies on all timescales and unexpected things have been discovered. Many questions have been answered, but some answers remain elusive (see Cuzzi et al 2010 for a review). Here we highlight the major ring science progress over the mission to date, and describe new observations planned for Cassini's final three years. Ring Composition and particle sizes: The rings are nearly all water ice with no other ices - so why are they reddish? The C Ring and Cassini Division are "dirtier" than the more massive B and A Rings, as shown by near-IR and, recently, microwave observations. Particle sizes, from stellar and radio occultations, vary from place to place. Ring structure, micro and macro: numerous spiral density waves and ubiquitous "self-gravity wakes" reveal processes which fostered planet formation in the solar system and elsewhere. However, big puzzles remain regarding the main ring divisions, the C Ring plateau structures, and the B Ring irregular structure. Moonlets, inside and out, seen and unseen: Two gaps contain sizeable moonlets, but more gaps seem to contain none; even smaller embedded "propeller" objects wander, systematically or randomly, through the A ring. Rubble pile ringmoons just outside the rings may escaped from the rings, and the recently discovered "Peggy" may be trying this as we watch. Impact bombardment of the rings: Comet fragments set the rings to rippling on century-timescales, and boulders crash through hourly; meanwhile, the constant hail of infalling Kuiper belt material has a lower mass flux than previously thought. Origin and Age of the Rings: The ring mass and bombardment play key roles. The ring mass is well known everywhere but in the B Ring (where most of it is). New models suggest how tidal breakup of evolving moons may have formed massive ancient rings, of which the current ring is just a shadow. During its last three years, the Cassini tour profile will allow entirely new

  20. Hot piston ring tests

    NASA Technical Reports Server (NTRS)

    Allen, David J.; Tomazic, William A.

    1987-01-01

    As part of the DOE/NASA Automotive Stirling Engine Project, tests were made at NASA Lewis Research Center to determine whether appendix gap losses could be reduced and Stirling engine performance increased by installing an additional piston ring near the top of each piston dome. An MTI-designed upgraded Mod I Automotive Stirling Engine was used. Unlike the conventional rings at the bottom of the piston, these hot rings operated in a high temperature environment (700 C). They were made of a high temperature alloy (Stellite 6B) and a high temperature solid lubricant coating (NASA Lewis-developed PS-200) was applied to the cylinder walls. Engine tests were run at 5, 10, and 15 MPa operating pressure over a range of operating speeds. Tests were run both with hot rings and without to provide a baseline for comparison. Minimum data to assess the potential of both the hot rings and high temperature low friction coating was obtained. Results indicated a slight increase in power and efficiency, an increase over and above the friction loss introduced by the hot rings. Seal leakage measurements showed a significant reduction. Wear on both rings and coating was low.

  1. Recovery effects due to the interaction between nuclear and electronic energy losses in SiC irradiated with a dual-ion beam

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    Single and dual-beam ion irradiations of silicon carbide (SiC) were performed to study possible Synergetic effects between Nuclear (Sn) and Electronic (Se) Energy Losses. Results obtained combining Rutherford backscattering in channeling conditions, Raman spectroscopy, and transmission electron microscopy techniques show that dual-beam irradiation of SiC induces a dramatic change in the final sample microstructure with a substantial decrease of radiation damage as compared to single-beam irradiation. Actually, a defective layer containing dislocations is formed upon dual-beam irradiation (Sn&Se), whereas single low-energy irradiation (Sn alone) or even sequential (Sn + Se) irradiations lead to full amorphization. The healing process is ascribed to the electronic excitation arising from the electronic energy loss of swift ions. These results shed new light on the long-standing puzzling problem of the existence of a possible synergy between Sn and Se in ion-irradiation experiments. This work is interesting for both fundamental understanding of the ion-solid interactions and technological applications in the nuclear industry where recovery Sn/Se effects may preserve the integrity of nuclear devices.

  2. Field reversed ion rings

    SciTech Connect

    Sudan, R.N.; Omelchenko, Y.A.

    1995-09-01

    In typical field-reversed ion ring experiments, an intense annular ion beam is injected across a plasma-filled magnetic cusp region into a neutral gas immersed in a ramped solenoidal magnetic field. Assuming the characteristic ionization time is much shorter than the long ({ital t}{approx_gt}2{pi}/{Omega}{sub {ital i}}) beam evolution time scale, we investigate the formation of an ion ring in the background plasma followed by field reversal, using a 21/2-D hybrid, PIC code FIRE, in which the beam and background ions are treated as particles and the electrons as a massless fluid. We show that beam bunching and trapping occurs downstream in a ramped magnetic field for an appropriate set of experimental parameters. We find that a compact ion ring is formed and a large field reversal {zeta}={delta}{ital B}/{ital B}{approx_gt}1 on axis develops. We also observe significant deceleration of the ring on reflection due to the transfer of its axial momentum to the background ions, which creates favorable trapping conditions. {copyright} {ital 1995 American Institute of Physics.}

  3. AN ALTERNATIVE LATTICE FOR THE SPALLATION NEUTRON SOURCE ACCUMULATOR RING.

    SciTech Connect

    GARDNER,C.J.; LEE,Y.Y.; TSOUPAS,N.; WEI,J.

    1999-03-29

    As a key component of the Spallation Neutron Source (SNS) Project, the Accumulator Ring will collect the proton beam from the SNS LINAC at an intensity of 2 x 10{sup 14} per pulse at 60 Hz for a total power of 2 MW, exceeding present performance value of existing facilities. Requirements of minimum beam loss for hands-on maintenance and flexibility for future upgrade are essential for the lattice design. In this paper, we study an alternative lattice emphasizing various injection schemes and flexibility for future upgrade. Working points, sextupole families for chromaticity control, and alternate extraction schemes are also considered.

  4. RANDOM AND SYSTEMATIC FIELD ERRORS IN THE SNS RING: A STUDY OF THEIR EFFECTS AND COMPENSATION

    SciTech Connect

    GARDNER,C.J.; LEE,Y.Y.; WENG,W.T.

    1998-06-22

    The Accumulator Ring for the proposed Spallation Neutron Source (SNS) [l] is to accept a 1 ms beam pulse from a 1 GeV Proton Linac at a repetition rate of 60 Hz. For each beam pulse, 10{sup 14} protons (some 1,000 turns) are to be accumulated via charge-exchange injection and then promptly extracted to an external target for the production of neutrons by spallation. At this very high intensity, stringent limits (less than two parts in 10,000 per pulse) on beam loss during accumulation must be imposed in order to keep activation of ring components at an acceptable level. To stay within the desired limit, the effects of random and systematic field errors in the ring require careful attention. This paper describes the authors studies of these effects and the magnetic corrector schemes for their compensation.

  5. Vascular ring

    MedlinePlus

    ... with aberrant subclavian and left ligamentum ateriosus; Congenital heart defect - vascular ring; Birth defect heart - vascular ring ... accounts for less than 1% of all congenital heart problems. The condition occurs as often in males ...

  6. Neptune's rings

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This 591-second exposure of the rings of Neptune were taken with the clear filter by the Voyager 2 wide-angle camera. The two main rings are clearly visible and appear complete over the region imaged. Also visible in this image is the inner faint ring and the faint band which extends smoothly from the ring roughly halfway between the two bright rings. Both of these newly discovered rings are broad and much fainter than the two narrow rings. The bright glare is due to over-exposure of the crescent on Neptune. Numerous bright stars are evident in the background. Both bright rings have material throughout their entire orbit, and are therefore continuous. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.

  7. Ion clearing the the XLS-ring

    SciTech Connect

    Bozoki, E.S.; Halama, H.

    1990-01-01

    The mechanism of ion capture by the beam, their effects on the beam as well as ways to clear the ions are discussed. Special attention is given to these questions for the SXLS ring. 20 refs., 5 figs., 4 tabs.

  8. 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

    NASA Astrophysics Data System (ADS)

    Hotchi, H.; Tani, N.; Watanabe, Y.; Harada, H.; Kato, S.; Okabe, K.; Saha, P. K.; Tamura, F.; Yoshimoto, M.

    2016-01-01

    In the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex, transverse injection painting is utilized not only to suppress space-charge induced beam loss in the low energy region but also to mitigate foil scattering beam loss during charge-exchange injection. The space-charge induced beam loss is well minimized by the combination of modest transverse painting and full longitudinal painting. But, for sufficiently mitigating the foil scattering part of beam loss, the transverse painting area has to be further expanded. However, such a wide-ranging transverse painting had not been realized until recently due to beta function beating caused by edge focusing of pulsed injection bump magnets during injection. This beta function beating additionally excites random betatron resonances through a distortion of the lattice superperiodicity, and its resultant deterioration of the betatron motion stability causes significant extra beam loss when expanding the transverse painting area. To solve this issue, we newly installed pulse-type quadrupole correctors to compensate the beta function beating. This paper presents recent experimental results on this correction scheme for suppressing the extra beam loss, while discussing the beam loss and its mitigation mechanisms with the corresponding numerical simulations.

  9. Beam-Bem interactions

    SciTech Connect

    Kim, Hyung Jin; /Fermilab

    2011-12-01

    In high energy storage-ring colliders, the nonlinear effect arising from beam-beam interactions is a major source that leads to the emittance growth, the reduction of beam life time, and limits the collider luminosity. In this paper, two models of beam-beam interactions are introduced, which are weak-strong and strong-strong beam-beam interactions. In addition, space-charge model is introduced.

  10. HESYRL storage ring vacuum system

    SciTech Connect

    Li, G.; Pang, Y.; Wang, Y.; Zhou, H.; Zhang, Z.; Jiang, D.; Xu, B.; Xu, S.

    1988-09-30

    The Storage Ring Vacuum System of the Synchrotron Radiation source project of HESYRL (Hefei Synchrotron Radiation Laboratory) in USTC, Hefei, Anhui, China, will be completed this year. Since the designed beam current of the 800 MeV electron storage ring is 300 mA, synchrotron radiation and hence high photon stimulated degassing will occur in the vacuum chamber. In order to get the stored beam lifetime of several hours, the pressure must be maintained at 10/sup -8/ approx.10/sup -9/ Torr. The gas desorption from synchrotron radiation and thermal outgas has been calculated. The UHV system of the storage ring and vacuum pretreatment methods are described in this paper.

  11. ISABELLE accelerator software, control system, and beam diagnostic philosophy

    SciTech Connect

    Cornacchia, M.; Humphrey, J.W.; Niederer, J.; Poole, J.H.

    1981-01-01

    The ISABELLE Project combines two large proton accelerators with two storage rings in the same facility using superconducting magnet technology. This combination leads to severe constraints on beam loss in magnets and involves complex treatment of magnetic field imperfections and correction elements. The consequent demands placed upon beam diagnostics, accelerator model programs, and the computer oriented control system are discussed in terms of an illustrative operation scenario.

  12. 6D Cooling of a Circulating Muon Beam

    SciTech Connect

    Garren, A.; Cline, D.; Kahn, S.; Kirk, H.; Mills, F.

    2006-03-20

    We discuss the conceptual design of a system to reduce the 6D emittance of a circulating muon beam. This system utilizes ionization cooling to achieve 6D phase reduction of the beam. Our design is based on a hydrogen gas filled ring which incorporates optics consisting of weak-focusing dipoles and 200 MHz rf cavities which restore the ionization energy loss due to the muons traversing the hydrogen gas.

  13. Recent study of beam stability in the PSR

    SciTech Connect

    Wang, T.S.F.; Cooper, R.; Fitzgerald, D.; Frankle, S.; Hardek, T.; Hutson, R.; Macek, R.; Ohmori, C.; Plum, M.; Thiessen, H.; Wilkinson, C.; Colton, E.; Neuffer, D.; Rees, G.

    1993-06-01

    A fast transverse instability with beam loss has been observed in the 800 MeV Los Alamos Pro Ring (PSR) when the injected beam intensity reaches 2 - 4 {times} 10{sup 13} protons per pulse. Previous observations in that the instability is most likely driven by electrons trapped within the proton beam. Theoretical study shown that beam leakage into the inter-bunch gap leads to electron trapping. Recent experiments were carried out by using the newly implemented ``pinger`` and by varying the machine transition gamma to explore further the ``e-p`` instability and the nature of the instability. This paper summarizes some of these recent experimental results and theoretical studies.

  14. Recent study of beam stability in the PSR

    SciTech Connect

    Wang, T.S.F.; Cooper, R.; Fitzgerald, D.; Frankle, S.; Hardek, T.; Hutson, R.; Macek, R.; Ohmori, C.; Plum, M.; Thiessen, H.; Wilkinson, C. ); Colton, E. ); Neuffer, D. ); Rees, G. )

    1993-01-01

    A fast transverse instability with beam loss has been observed in the 800 MeV Los Alamos Pro Ring (PSR) when the injected beam intensity reaches 2 - 4 [times] 10[sup 13] protons per pulse. Previous observations in that the instability is most likely driven by electrons trapped within the proton beam. Theoretical study shown that beam leakage into the inter-bunch gap leads to electron trapping. Recent experiments were carried out by using the newly implemented pinger'' and by varying the machine transition gamma to explore further the e-p'' instability and the nature of the instability. This paper summarizes some of these recent experimental results and theoretical studies.

  15. Commissioning results of the APS storage ring diagnostics systems

    SciTech Connect

    Lumpkin, A.H.

    1996-12-31

    Initial commissionings of the Advanced Photon Source (APS) 7-GeV storage ring and its diagnostics systems have been done. Early studies involved single-bunch measurements for beam transverse size ({sigma}{sub x} {approx} 150 {mu}m, {sigma}{sub y} {approx} 50 {mu}m), current, injection losses, and bunch length. The diagnostics have been used in studies related to the detection of an extra contribution to beam jitter at {approximately} 6.5 Hz frequency; observation of bunch lengthening ({sigma} {approx} 30 to 60 ps) with single-bunch current; observation of an induced vertical, head-tail instability; and detection of a small orbit change with insertion device gap position. More recently, operations at 100-mA stored-beam current, the baseline design goal, have been achieved with the support of beam characterizations.

  16. Design and optimization of a longitudinal feedback kicker cavity for the HLS-II storage ring

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Z. Wu, W.; He, Duo-Hui; K. Wu, Y.

    2013-03-01

    In the Hefei Light Source (HLS) storage ring, multibunch operation is used to obtain a high luminosity. Multibunch instabilities can severely limit light source performance with a variety of negative impacts, including beam loss, low injection efficiency, and overall degradation of the beam quality. Instabilities of a multibunch beam can be mitigated using certain techniques including increasing natural damping (operating at a higher energy), lowering the beam current, and increasing Landau damping. However, these methods are not adequate to stabilize a multibunch electron beam at a low energy and with a high current. In order to combat beam instabilities in the HLS storage ring, active feedback systems including a longitudinal feedback system (LFB) and a transverse feedback system (TFB) will be developed as part of the HLS upgrade project, the HLS- II storage ring project. As a key component of the longitudinal bunch-by-bunch feedback system, an LFB kicker cavity with a wide bandwidth and high shunt impedance is required. In this paper we report our work on the design of the LFB kicker cavity for the HLS- II storage ring and present the new tuning and optimization techniques developed in designing this high performance LFB kicker.

  17. A new ring-shaped graphite monitor ionization chamber

    NASA Astrophysics Data System (ADS)

    Yoshizumi, M. T.; Caldas, L. V. E.

    2010-07-01

    A ring-shaped monitor ionization chamber was developed at the Instituto de Pesquisas Energéticas e Nucleares. This ionization chamber presents an entrance window of aluminized polyester foil. The guard ring and collecting electrode are made of graphite coated Lucite plates. The main difference between this new ionization chamber and commercial monitor chambers is its ring-shaped design. The new monitor chamber has a central hole, allowing the passage of the direct radiation beam without attenuation; only the penumbra radiation is measured by the sensitive volume. This kind of ionization chamber design has already been tested, but using aluminium electrodes. By changing the electrode material from aluminium to a graphite coating, an improvement in the chamber response stability was expected. The pre-operational tests, as saturation curve, recombination loss and polarity effect showed satisfactory results. The repeatability and the long-term stability tests were also evaluated, showing good agreement with international recommendations.

  18. Rf System Requirements for JLab’s MEIC Collider Ring

    SciTech Connect

    Wang, Shaoheng; Li, Rui; Rimmer, Robert A.; Wang, Haipeng; Zhang, Yuhong

    2013-06-01

    The Medium-energy Electron Ion Collider (MEIC), proposed by Jefferson Lab, consists of a series of accelerators. At the top energy are the electron and ion collider rings. For the ion ring, it accelerates five long ion bunches to colliding energy and rebunches ions into a train of very short bunches before colliding. A set of low frequency RF system is needed for the long ion bunch energy ramping. Another set of high frequency RF cavities is needed to rebunch ions. For the electron ring, superconducting RF (SRF) cavities are needed to compensate the synchrotron radiation energy loss. The impedance of the SRF cavities must be low enough to keep the high current electron beam stable. The preliminary design requirements of these RF cavities are presented.

  19. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Gordon, M. K.; Araki, S.; Black, G. J.; Bosh, A. S.; Brahic, A.; Brooks, S. M.; Charnoz, S.; Colwell, J. E.; Cuzzi, J. N.; Dones, L.; Durisen, R. H.; Esposito, L. W.; Ferrari, C.; Festou, M.; French, R. G.; Giuliatti-Winter, S. M.; Graps, A. L.; Hamilton, D. P.; Horanyi, M.; Karjalainen, R. M.; Krivov, A. V.; Krueger, H.; Larson, S. M.; Levison, H. F.; Lewis, M. C.; Lissauer, J. J.; Murray, C. D.; Namouni, F.; Nicholson, P. D.; Olkin, C. B.; Poulet, F.; Rappaport, N. J.; Salo, H. J.; Schmidt, J.; Showalter, M. R.; Spahn, F.; Spilker, L. J.; Srama, R.; Stewart, G. R.; Yanamandra-Fisher, P.

    2002-08-01

    The past two decades have witnessed dramatic changes in our view and understanding of planetary rings. We now know that each of the giant planets in the Solar System possesses a complex and unique ring system. Recent studies have identified complex gravitational interactions between the rings and their retinues of attendant satellites. Among the four known ring systems, we see elegant examples of Lindblad and corotation resonances (first invoked in the context of galactic disks), electromagnetic resonances, spiral density waves and bending waves, narrow ringlets which exhibit internal modes due to collective instabilities, sharp-edged gaps maintained via tidal torques from embedded moonlets, and tenuous dust belts created by meteoroid impact onto, or collisions between, parent bodies. Yet, as far as we have come, our understanding is far from complete. The fundamental questions confronting ring scientists at the beginning of the twenty-first century are those regarding the origin, age and evolution of the various ring systems, in the broadest context. Understanding the origin and age requires us to know the current ring properties, and to understand the dominant evolutionary processes and how they influence ring properties. Here we discuss a prioritized list of the key questions, the answers to which would provide the greatest improvement in our understanding of planetary rings. We then outline the initiatives, missions, and other supporting activities needed to address those questions, and recommend priorities for the coming decade in planetary ring science.

  20. Condenser for illuminating a ring field

    DOEpatents

    Sweatt, W.C.

    1994-11-01

    A series of segments of a parent aspheric mirror having one foci at a point source of radiation and the other foci at the radius of a ring field have all but one or all of their beams translated and rotated by sets of mirrors such that all of the beams pass through the real entrance pupil of a ring field camera about one of the beams and fall onto the ring field radius as a coincident image as an arc of the ring field. 5 figs.

  1. Condenser for illuminating a ring field

    DOEpatents

    Sweatt, William C.

    1994-01-01

    A series of segments of a parent aspheric mirror having one foci at at a si-point source of radiation and the other foci at the radius of a ring field have all but one or all of their beams translated and rotated by sets of mirrors such that all of the beams pass through the real entrance pupil of a ring field camera about one of the beams and fall onto the ring field radius as a coincident image as an arc of the ring field.

  2. Theoretical Investigation on the Scale Factor of a Triple Ring Cavity to BE Used in Frequency Sensitive Resonant Gyroscopes

    NASA Astrophysics Data System (ADS)

    Ciminelli, C.; Campanella, C. E.; Dell'Olio, F.; Campanella, C. M.; Armenise, M. N.

    2013-07-01

    In this paper we study a multi-ring resonant structure including three evanescently coupled ring resonators (named triple ring resonator,TRR), with different ring radii and coupling coefficients, and coupled to two bus waveguides. The potential application of a TRR as a rotationsensor is analyzed and its advantages over a single ring resonator (SRR) under rotation conditions are also highlighted. When the coupledrings have different size and their inter-ring coupling coefficients are lower than the ring-bus coupling coefficients, the resonance frequencydifference between two counter-propagating beams induced by rotation is enhanced with respect to that of a single ring resonator (SRR)with the same footprint. The scale factor of the rotating TRR, which depends on the structural parameters (i.e. inter-ring and ring-buscoupling coefficients, lengths of the rings, overall propagation loss within the rings), is up to 1.88 times the value of the scale factor of aSRR, which depends only on the ring radius, by assuming that the waveguide structure in both configurations is the same. This promisingnumerical achievement results in a reduction of the sensor footprint of about two times, with respect to a single ring with the same scalefactor. The results obtained may be useful to define new configurations of frequency sensitive optical gyros in low-loss technology, havinga small volume. In fact, by properly choosing the structural parameters, the spectral response of the TRR is forced to assume a shape moresensitive to the resonant frequency shift due to the rotation with respect to that one of a SRR.

  3. Storage ring development at the National Synchrotron Light Source

    SciTech Connect

    Krinsky, S.; Bittner, J.; Fauchet, A.M.; Johnson, E.D.; Keane, J.; Murphy, J.; Nawrocky, R.J.; Rogers, J.; Singh, O.V.; Yu, L.H.

    1991-09-01

    This report contains papers on the following topics: Transverse Beam Profile Monitor; Bunch Length Measurements in the VUV Storage Ring; Photoelectric Effect Photon Beam Position Monitors; RF Receivers for Processing Electron Beam Pick-up Electrode Signals; Real-Time Global Orbit Feedback Systems; Local Orbit Feedback; Active Interlock System for High Power Insertion Devices in the X-ray Ring; Bunch Lengthening Cavity for the VUV Ring; SXLS Storage Ring Design.

  4. Electron Transfer Reduction of the Diazirine Ring in Gas-Phase Peptide Ions. On the Peculiar Loss of [NH4O] from Photoleucine

    NASA Astrophysics Data System (ADS)

    Marek, Aleš; Shaffer, Christopher J.; Pepin, Robert; Slováková, Kristina; Laszlo, Kenneth J.; Bush, Matthew F.; Tureček, František

    2015-03-01

    Electron transfer to gas-phase peptide ions with diazirine-containing amino acid residue photoleucine (L*) triggers diazirine ring reduction followed by cascades of residue-specific radical reactions. Upon electron transfer, substantial fractions of (GL*GGR +2H)+● cation-radicals undergo elimination of [NH4O] radicals and N2H2 molecules from the side chain. The side-chain dissociations are particularly prominent on collisional activation of long-lived (GL*GGR +2H)+● cation-radicals formed by electron transfer dissociation of noncovalent peptide-18-crown-6-ether ion complexes. The ion dissociation products were characterized by multistage tandem mass spectrometry (MSn) and ion mobility measurements. The elimination of [NH4O] was elucidated with the help of 2H, 15 N, and 18O-labeled peptide ions and found to specifically involve the amide oxygen of the N-terminal residue. The structures, energies, and electronic states of the peptide radical species were elucidated by a combination of near-UV photodissociation experiments and electron structure calculations combining ab initio and density functional theory methods. Electron transfer reaching the ground electronic states of charge reduced (GL*GGR +2H)+● cation-radicals was found to reduce the diazirine ring. In contrast, backbone N - Cα bond dissociations that represent a 60%-75% majority of all dissociations because of electron transfer are predicted to occur from excited electronic states.

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

    SciTech Connect

    Hamm, L.L.

    1998-10-07

    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.

  6. Absolute cascade-free cross-sections for the 2S to 2P transition in Zn(+) using electron-energy-loss and merged-beams methods

    NASA Technical Reports Server (NTRS)

    Smith, Steven J.; Man, K.-F.; Chutjian, A.; Mawhorter, R. J.; Williams, I. D.

    1991-01-01

    Absolute cascade-free excitation cross-sections in an ion have been measured for the resonance 2S to 2P transition in Zn(+) using electron-energy-loss and merged electron-ion beams methods. Measurements were carried out at electron energies of below threshold to 6 times threshold. Comparisons are made with 2-, 5-, and 15-state close-coupling and distorted-wave theories. There is good agreement between experiment and the 15-state close-coupling cross-sections over the energy range of the calculations.

  7. The vacuum system for the PEP II high energy ring straight sections

    SciTech Connect

    Wienands, U.; Daly, E.; Kulikov, A.; Kurita, N.; Nordby, M.; Perkins, C.; Reuter, E.; Seeman, J. T.

    1995-01-01

    The six straight sections of the PEP II High Energy Ring (HER) serve various functions: lattice tuning, beam injection and abort, providing space for rf cavities, longitudinal and transverse feedback, beam diagnostics and the interaction point. A stainless steel vacuum system has been designed; prototypes are currently being built. Cooling is required due to radiation coming from the last arc dipole and resistive losses in the vacuum chamber. Although the nominal beam current of the HER is 1 A the vacuum system is designed for 3 A to provide margin and an upgrade path. 5 refs., 7 figs.

  8. Capture, acceleration and bunching rf systems for the MEIC booster and storage rings

    SciTech Connect

    Wang, Shaoheng; Guo, Jiquan; Lin, Fanglei; Morozov, Vasiliy; Rimmer, Robert A.; Wang, Haipeng; Zhang, Yuhong

    2015-09-01

    The Medium-energy Electron Ion Collider (MEIC), proposed by Jefferson Lab, consists of a series of accelerators. The electron collider ring accepts electrons from CEBAF at energies from 3 to 12 GeV. Protons and ions are delivered to a booster and captured in a long bunch before being ramped and transferred to the ion collider ring. The ion collider ring accelerates a small number of long ion bunches to colliding energy before they are re-bunched into a high frequency train of very short bunches for colliding. Two sets of low frequency RF systems are needed for the long ion bunch energy ramping in the booster and ion collider ring. Another two sets of high frequency RF cavities are needed for re-bunching in the ion collider ring and compensating synchrotron radiation energy loss in the electron collider ring. The requirements from energy ramping, ion beam bunching, electron beam energy compensation, collective effects, beam loading and feedback capability, RF power capability, etc. are presented. The preliminary designs of these RF systems are presented. Concepts for the baseline cavity and RF station configurations are described, as well as some options that may allow more flexible injection and acceleration schemes.

  9. Planetary Rings

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.

    1994-01-01

    Just over two decades ago, Jim Pollack made a critical contribution to our understanding of planetary ring particle properties, and resolved a major apparent paradox between radar reflection and radio emission observations. At the time, particle properties were about all there were to study about planetary rings, and the fundamental questions were, why is Saturn the only planet with rings, how big are the particles, and what are they made of? Since then, we have received an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems into the complex webs of structure that we now know them to display. Insights gained from studies of these giant dynamical analogs have carried over into improved understanding of the formation of the planets themselves from particle disks, a subject very close to Jim's heart. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is ark emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system

  10. RHIC beam permit and quench detection communications system

    SciTech Connect

    Conkling, C.R. Jr.

    1997-07-01

    A beam permit module has been developed to concentrate RHIC, subsystem sensor outputs, permit beam, and initiate emergency shutdowns. The modules accept inputs from the vacuum, cryogenic, power supply, beam loss, and superconducting magnet quench detection systems. Modules are located at equipment locations around the RHIC ring. The modules are connected by three fiberoptic communications links; a beam permit link, and two magnet power supply interlock links. During operation, carrier presence allows beam. If a RHIC subsystem detects a fault, the beam permit carrier terminates - initiating a beam dump. If the fault was a superconducting magnet quench, a power supply interlock carrier terminates - initiating an emergency magnet power dump. In addition, the master module triggers an event to cause remote sensors to log and hold data at the time-of-failure.

  11. SNS RING INJECTION STRIPPED ELECTRON COLLECTION: DESIGN ANALYSIS AND TECHNICAL ISSUES.

    SciTech Connect

    LEE, Y.; MAHLER, G.; MENG, W.; RAPARIA, D.; WANG, L.; WEI, J.

    2005-05-16

    This paper describes the simulation studies on the motions of stripped electrons generated in the injection section of the Spallation Neutron Source (SNS) accumulator ring and the effective collection mechanism. Such studies are important for high intensity machines, in order to reduce beam loss and protect other components in the vicinity. The magnetic field is applied to guide electrons to a collector, which is located at the bottom of the beam vacuum chamber. Part of the study results with and without considering the interactions between electrons and materials are presented and discussed. The final engineering design of the electron collector (catcher). The electron multi-pacting induced by beam loss and residual gas ionization along the ring has been studied in detail [l]. In the SNS accumulator ring straight section, electrons are stripped from the injected H{sup -} beam through a carbon foil. These protons must make 1100 turns to be compressed from 1 ms Linac pulse into a 700 ns bunch with 2E14 protons. The stripped electrons will have the same initial velocity but twice the intensity (current) of the H{sup -} beam. In this paper, we report the studies on electrons, and the optimum design of the collector.

  12. 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

    SciTech Connect

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

    2010-09-14

    In 2009 the Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Center started free electron laser (FEL) operation. In order to continue to produce the bright and short-pulsed x-ray laser demanded by FEL scientists, this pioneer hard x-ray FEL requires a perfectly tailored magnetic field at the undulators, so that the photons generated at the electron wiggling path interact at the right phase with the electron beam. In such a precise system, small (>0.01%) radiation-induced alterations of the magnetic field in the permanent magnets could affect FEL performance. This paper describes the simulation studies of radiation fields in permanent magnets and the expected signal in the detectors. The transport of particles from the radiation sources (i.e. diagnostic insert) to the undulator magnets and to the beam loss monitors (BLM) was simulated with the intra nuclear cascade codes FLUKA and MARS15. In order to accurately reproduce the optics of LCLS, lattice capabilities and magnetic fields were enabled in FLUKA and betatron oscillations were validated against reference data. All electron events entering the BLMs were printed in data files. The paper also introduces the Radioactive Ion Beam Optimizer (RIBO) Monte Carlo 3-D code, which was used to read from the event files, to compute Cerenkov production and then to simulate the optical coupling of the BLM detectors, accounting for the transmission of light through the quartz.

  13. Low-loss pilot-beam delivery in hollow optical fiber for high-energy infrared laser light

    NASA Astrophysics Data System (ADS)

    Shi, Yi-Wei; Ito, Kentaro; Matsuura, Yuji; Miyagi, Mitsunobu

    2005-01-01

    New techniques were established in fabricating cyclic olefin polymer-coated silver (COP/Ag) hollow optical fiber. Low-loss properties in visible region were obtained owing to the smoother layers of silver and polymer. In silver layer plating, a SnCl2 solution pre-treatment was used to sensitize the inner surface of the glass capillary. A silver layer with an RMS surface roughness of 8 nm was obtained comparing with 18 nm RMS roughness without the pre-treatment. In the liquid-phase coating of the polymer layer, an ambient air of organic solvent was used in the whole process. A smoother polymer layer with RMS roughness of 10 nm was obtained comparing with 20 nm roughness when a normal nitrogen gas-flow was used. The straight and bending loss properties for the hollow fibers have been measured by using a CO2 laser and a red laser diode at the wavelengths of 10.6 μm and 0.63 μm. The straight losses were 0.4 dB and 1 dB for the hollow fiber (700 μmφ×1 m) made by the new developed fabrication techniques.

  14. The behavior of beams of relativistic non-thermal electrons under the influence of collisions and synchrotron losses

    NASA Technical Reports Server (NTRS)

    Mctiernan, James M.; Petrosian, Vahe

    1989-01-01

    For many astrophysical situations, such as in solar flares or cosmic gamma-ray bursts, continuum gamma rays with energies up to hundreds of MeV were observed, and can be interpreted to be due to bremsstrahlung radiation by relativistic electrons. The region of acceleration for these particles is not necessarily the same as the region in which the radiation is produced, and the effects of the transport of the electrons must be included in the general problem. Hence it is necessary to solve the kinetic equation for relativistic electrons, including all the interactions and loss mechanisms relevant at such energies. The resulting kinetic equation for non-thermal electrons, including the effects of Coulomb collisions and losses due to synchrotron emission, was solved analytically in some simple limiting cases, and numerically for the general cases including constant and varying background plasma density and magnetic field. New approximate analytic solutions are presented for collision dominated cases, for small pitch angles and all energies, synchrotron dominated cases, both steady-state and time dependent, for all pitch angles and energies, and for cases when both synchrotron and collisional energy losses are important, but for relativistic electrons. These analytic solutions are compared to the full numerical results in the proper limits. These results will be useful for calculation of spectra and angular distribution of the radiation (x rays, gamma-rays, and microwaves) emitted via synchrotron or bremsstrahlung processes by the electrons. These properties and their relevance to observations will be observed in subsequent papers.

  15. Collimator design for the NSNS accumulator ring

    SciTech Connect

    Ludewig, H.; Schmidt, E.; Aronson, A.; Walker, J.; Todosow, M.; Mughabghab, S.

    1997-10-01

    Collimators are used to remove halo or off-momentum particles from the main proton beam. Off-momentum particles are removed by situating collimators in high dispersion areas of the beam. In addition to removing halo particles collimators will also act as shielding for the remainder of the accelerator structures. Thus, collimators reduce uncontrolled losses around the ring and reduce activation of the accelerator components. Requirements and performance goals for the collimator are summarized. In order to meet these goals a self-shielding collimator configuration will be designed. An arrangement consisting of a layered structure will be considered. The initial layers (in the direction of the proton beam) are transparent to protons, and become progressively less transparent (blacker) with depth into the collimator. In addition, a high density (iron) shield will be added around this structure, particularly in the backward direction, to attenuate any reflected protons. The protons are stopped in the approximate center of the collimator, and thus the bulk of the secondary particles will also be generated there. Since these secondary particles are primarily produced isotropically their leakage path length will be maximized in this manner (high probability of capture or attenuation). In the case of neutrons a black layer is included at each end in order to further minimize their leakage in the direction of the beam. This design will therefore minimize the activation of surrounding accelerator components.

  16. Vascular rings.

    PubMed

    Backer, Carl L; Mongé, Michael C; Popescu, Andrada R; Eltayeb, Osama M; Rastatter, Jeffrey C; Rigsby, Cynthia K

    2016-06-01

    The term vascular ring refers to congenital vascular anomalies of the aortic arch system that compress the esophagus and trachea, causing symptoms related to those two structures. The most common vascular rings are double aortic arch and right aortic arch with left ligamentum. Pulmonary artery sling is rare and these patients need to be carefully evaluated for frequently associated tracheal stenosis. Another cause of tracheal compression occurring only in infants is the innominate artery compression syndrome. In the current era, the diagnosis of a vascular ring is best established by CT imaging that can accurately delineate the anatomy of the vascular ring and associated tracheal pathology. For patients with a right aortic arch there recently has been an increased recognition of a structure called a Kommerell diverticulum which may require resection and transfer of the left subclavian artery to the left carotid artery. A very rare vascular ring is the circumflex aorta that is now treated with the aortic uncrossing operation. Patients with vascular rings should all have an echocardiogram because of the incidence of associated congenital heart disease. We also recommend bronchoscopy to assess for additional tracheal pathology and provide an assessment of the degree of tracheomalacia and bronchomalacia. The outcomes of surgical intervention are excellent and most patients have complete resolution of symptoms over a period of time. PMID:27301603

  17. Loss cone boundary measurement using diagnostic neutral beam and neutral particle analyzer in a compact helical system

    SciTech Connect

    Matsushita, H.; Ida, K.; Okamura, S.; Isobe, M.; Akiyama, R.; Yoshimura, Y.

    2004-10-01

    A horizontally scannable diagnostic neutral beam (DNB) has been installed on the compact helical system (CHS) in order to study the confinement of energetic ions with different pitch angles by varying the injection angle. The DNB has been designed to provide energetic ions as a test particle source with (1) no heating to background plasma and (2) small divergence angle. A charge-exchange neutral particle analyzer (NPA) to measure energetic ions injected by the DNB is also scannable and varies the observation angle on the equatorial plane in CHS. A combination of horizontally scannable DNB and NPA provides information on whether the energetic ions with different pitch angle are confined in the plasma or immediately lost. The experimental results are consistent with the prediction of single particle full orbit calculation in CHS.

  18. The next linear collider damping ring lattices

    SciTech Connect

    Wolski, Andrzej; Corlett, John N.

    2001-06-20

    We report on the lattice design of the Next Linear Collider (NLC) damping rings. The damping rings are required to provide low emittance electron and positron bunch trains to the NLC linacs, at a rate of 120 Hz. We present an optical design, based on a theoretical minimum emittance (TME) lattice, to produce the required normalized extracted beam emittances gex = 3 mm-mrad and gey = 0.02 mm mrad. An assessment of dynamic aperture and non-linear effects is given. The positron pre-damping ring, required to reduce the emittance of the positron beam such that it may be accepted by a main damping ring, is also described.

  19. Status of the SLC damping rings

    SciTech Connect

    Hutton, A.M.; Davies-White, W.A.; Delahaye, J.P.; Fieguth, T.H.; Hofmann, A.; Jager, J.; Kloeppel, P.K.; Lee, M.J.; Linebarger, W.A.; Rivkin, L.

    1985-06-01

    Electron beams of full design energy 1.21 GeV and nearly full design intensity 4 x 10/sup 10/ particles/pulse (design 5 x 10/sup 10/) have been extracted from the Stanford Linac and successfully stored in the electron damping ring. Beams of less intensity have been extracted from the ring and reinjected into the Linac. The present intensity limits are not thought to be fundamental. The operating experience with the electron ring and the status of the construction of the positron ring will be discussed. 11 refs., 1 fig., 2 tabs.

  20. Optics of electron beam in the Recycler

    SciTech Connect

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

    2005-11-01

    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 {approx}0.2 A or higher DC electron beam have to be parallel in the cooling section, within {approx}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 {approx}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 analyzed 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.

  1. Optics of Electron Beam in the Recycler

    SciTech Connect

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

    2006-03-20

    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 {approx}0.2 A or higher DC electron beam have to be parallel in the cooling section, within {approx} 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 {approx}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.

  2. Numerical analysis of ac loss in bifilar stacks and coils of ion beam assisted deposition YBCO coated conductors

    SciTech Connect

    Nguyen, Doan N.; Ashworth, Stephen P.; Willis, Jeffrey O.

    2009-03-15

    In this paper we present a finite element model using the commercial COMSOL software package for calculating the ac loss in bifilar stacks of high temperature superconducting tape. In the model, the current-voltage relationship characterizing the superconducting properties is assumed to follow a power law. The calculations were performed for infinite bifilar stacks with different values of layer-to-layer separation D. With appropriate settings for the boundary conditions, the numerical results agree well with the analytical data obtained from a recently proposed model [J. R. Clem, Phys. Rev. B 77, 134506 (2008)]. The numerical approach was also used to investigate the end effects in a bifilar stack to answer the following question: how many layers away from the end of a stack are required before the environment of a given layer is identical to that in an infinite stack? We find that the answer to this question depends strongly on the value of D. Based on this study, a model for calculating the ac loss in bifilar noninductively wound coils with a finite number of turns is proposed.

  3. Reflex ring laser amplifier system

    DOEpatents

    Summers, Mark A.

    1985-01-01

    A laser pulse is injected into an unstable ring resonator-amplifier structure. Inside this resonator the laser pulse is amplified, spatially filtered and magnified. The laser pulse is recirculated in the resonator, being amplified, filtered and magnified on each pass. The magnification is chosen so that the beam passes through the amplifier in concentric non-overlapping regions similar to a single pass MOPA. After a number of passes around the ring resonator the laser pulse is spatially large enough to exit the ring resonator system by passing around an output mirror.

  4. Efficient Injection of Electron Beams into Magnetic Guide Fields

    SciTech Connect

    Chorny, V.; Cooperstein, G.; Dubyna, V.; Frolov, O.; Harper-Slaboszewicz, V.; Hinshelwood, D.; Schneider, R.; Solovyov, V.; Tsepilov, H.; Vitkovitsky, I.; Ware, K,

    1999-06-08

    Preliminary experimental and modeling study of injection and transport of high current electron beams in current-neutralized background gas has been performed. Initial analysis of the results indicates that high current triaxial ring diode operates very reproducibly in the pinch mode. High current density beam can be injected efficiently into the drift region, using azimuthal guide field with reduced intensity near the injection region. This was shown to improve the effectiveness of capturing the beam for the transport. The transport length was insufficient to measure losses, such as would arise from scattering with the background gas.

  5. Measurement of Beam Lifetime and Applications for SPEAR3

    SciTech Connect

    Huang, Xiaobiao; Corbett, Jeff; /SLAC

    2011-04-05

    Beam lifetime studies for the SPEAR3 storage ring are presented. The three lifetime components are separated with lifetime measurements under various combinations of beam currents and fill patterns and vertical scraper scans. Touschek lifetime is studied with rf voltage scans and with the horizontal or vertical scrapers inserted. The measurements are explained with calculations based on the calibrated lattice model. Quantum lifetime measurements are performed with reduced longitudinal and horizontal apertures, respectively, from which we deduce the radiation energy loss down to a few keV per revolution and the horizontal beam size.

  6. Simulation of radiation damping in rings, using stepwise ray-tracing methods

    NASA Astrophysics Data System (ADS)

    Méot, F.

    2015-06-01

    The ray-tracing code Zgoubi computes particle trajectories in arbitrary magnetic and/or electric field maps or analytical field models. It includes a built-in fitting procedure, spin tracking, many Monte Carlo processes. The accuracy of the integration method makes it an efficient tool for multi-turn tracking in periodic machines. Energy loss by synchrotron radiation, based on Monte Carlo techniques, had been introduced in Zgoubi in the early 2000s for studies regarding the linear collider beam delivery system. However, only recently has this Monte Carlo tool been used for systematic beam dynamics and spin diffusion studies in rings, including the eRHIC electron-ion collider project at the Brookhaven National Laboratory. Some beam dynamics aspects of this recent use of Zgoubi capabilities, including considerations of accuracy as well as further benchmarking in the presence of synchrotron radiation in rings, are reported here.

  7. Simulation of radiation damping in rings, using stepwise ray-tracing methods

    DOE PAGESBeta

    Meot, F.

    2015-06-26

    The ray-tracing code Zgoubi computes particle trajectories in arbitrary magnetic and/or electric field maps or analytical field models. It includes a built-in fitting procedure, spin tracking many Monte Carlo processes. The accuracy of the integration method makes it an efficient tool for multi-turn tracking in periodic machines. Energy loss by synchrotron radiation, based on Monte Carlo techniques, had been introduced in Zgoubi in the early 2000s for studies regarding the linear collider beam delivery system. However, only recently has this Monte Carlo tool been used for systematic beam dynamics and spin diffusion studies in rings, including eRHIC electron-ion collider projectmore » at the Brookhaven National Laboratory. Some beam dynamics aspects of this recent use of Zgoubi capabilities, including considerations of accuracy as well as further benchmarking in the presence of synchrotron radiation in rings, are reported here.« less

  8. Simulation of radiation damping in rings, using stepwise ray-tracing methods

    SciTech Connect

    Meot, F.

    2015-06-26

    The ray-tracing code Zgoubi computes particle trajectories in arbitrary magnetic and/or electric field maps or analytical field models. It includes a built-in fitting procedure, spin tracking many Monte Carlo processes. The accuracy of the integration method makes it an efficient tool for multi-turn tracking in periodic machines. Energy loss by synchrotron radiation, based on Monte Carlo techniques, had been introduced in Zgoubi in the early 2000s for studies regarding the linear collider beam delivery system. However, only recently has this Monte Carlo tool been used for systematic beam dynamics and spin diffusion studies in rings, including eRHIC electron-ion collider project at the Brookhaven National Laboratory. Some beam dynamics aspects of this recent use of Zgoubi capabilities, including considerations of accuracy as well as further benchmarking in the presence of synchrotron radiation in rings, are reported here.

  9. STUDY OF LONGITUDINAL INJECTION/STACKING IN THE SNS ACUMMULATOR RING.

    SciTech Connect

    BEEBE-WANG,J.

    1999-03-29

    Various longitudinal distributions, resulting from the specific injection and stacking methods, are considered to minimize longitudinal and transverse instabilities and particle losses in SNS accumulator ring. The longitudinal phase space paintings by linac energy ramping, increased linac energy spread and the use of a random phase RF debunching cavity are reported. Bunch lengthening and beam in gap rate as functions of injection energy spread, RF voltage and injection energy error is summarized. Finally, the energy error tolerance is concluded.

  10. Thermal emission from Saturn's rings at 380 microns

    SciTech Connect

    Roellig, T.L.; Werner, M.W.; Becklin, E.E.

    1988-03-01

    Two different techniques have been used to derive the Saturn disk's ring brightness temperatures from 380-micron observations: (1) comparisons of these wide-beam observation disk-ring system results with those obtained for an earlier epoch, when the rings were edge-on, then differencing the two measurements to obtain a value for the rings' contribution; and (2) ring contribution resolution during scanning along the disk-ring plane, to yield a B-ring brightness temperature of 39 + or - 8 K at 380 microns. The results obtained indicate a gradual decrease of observed ring brightness temperature from the IR to the radio wavelength range. 24 references.

  11. Thermal emission from Saturn's rings at 380 microns

    NASA Technical Reports Server (NTRS)

    Roellig, Thomas L.; Werner, Michael W.; Becklin, Eric E.

    1988-01-01

    Two different techniques have been used to derive the Saturn disk's ring brightness temperatures from 380-micron observations: (1) comparisons of these wide-beam observation disk-ring system results with those obtained for an earlier epoch, when the rings were edge-on, then differencing the two measurements to obtain a value for the rings' contribution; and (2) ring contribution resolution during scanning along the disk-ring plane, to yield a B-ring brightness temperature of 39 + or - 8 K at 380 microns. The results obtained indicate a gradual decrease of observed ring brightness temperature from the IR to the radio wavelength range.

  12. Ring cusp/hollow cathode discharge chamber performance studies. [ion propulsion

    NASA Technical Reports Server (NTRS)

    Vaughn, J. A.; Wilbur, Paul J.

    1988-01-01

    An experimental study was performed to determine the effects of hollow cathode position, anode position, and ring cusp magnetic field configuration and strength on discharge chamber performance. The results are presented in terms of comparative plasma ion energy cost, extracted ion fraction, and beam profile data. Such comparisons are used to demonstrate whether changes in performance are caused by changes in the loss rate of primary electrons to the anode or the loss rate of ions to discharge chamber walls or cathode and anode surfaces. Results show: (1) the rate of primary electron loss to the anode decreases as the anode is moved downstream of the ring cusp toward the screen grid; (2) the loss rate of ions to hollow cathode surfaces are excessive if the cathode is located upstream of a point of peak magnetic flux density at the discharge chamber centerline; and (3) the fraction of the ions produced that are lost to discharge chamber walls and ring magnet surfaces is reduced by positioning of the magnet rings so the plasma density is uniform over the grid surface, and adjusting their strength to a level where it is sufficient to prevent excessive ion losses by Bohm diffusion.

  13. Towards the clinical implementation of iterative low-dose cone-beam CT reconstruction in image-guided radiation therapy: Cone/ring artifact correction and multiple GPU implementation

    SciTech Connect

    Yan, Hao E-mail: xun.jia@utsouthwestern.edu; Shi, Feng; Jiang, Steve B.; Jia, Xun E-mail: xun.jia@utsouthwestern.edu; Wang, Xiaoyu; Cervino, Laura; Bai, Ti; Folkerts, Michael

    2014-11-01

    Purpose: Compressed sensing (CS)-based iterative reconstruction (IR) techniques are able to reconstruct cone-beam CT (CBCT) images from undersampled noisy data, allowing for imaging dose reduction. However, there are a few practical concerns preventing the clinical implementation of these techniques. On the image quality side, data truncation along the superior–inferior direction under the cone-beam geometry produces severe cone artifacts in the reconstructed images. Ring artifacts are also seen in the half-fan scan mode. On the reconstruction efficiency side, the long computation time hinders clinical use in image-guided radiation therapy (IGRT). Methods: Image quality improvement methods are proposed to mitigate the cone and ring image artifacts in IR. The basic idea is to use weighting factors in the IR data fidelity term to improve projection data consistency with the reconstructed volume. In order to improve the computational efficiency, a multiple graphics processing units (GPUs)-based CS-IR system was developed. The parallelization scheme, detailed analyses of computation time at each step, their relationship with image resolution, and the acceleration factors were studied. The whole system was evaluated in various phantom and patient cases. Results: Ring artifacts can be mitigated by properly designing a weighting factor as a function of the spatial location on the detector. As for the cone artifact, without applying a correction method, it contaminated 13 out of 80 slices in a head-neck case (full-fan). Contamination was even more severe in a pelvis case under half-fan mode, where 36 out of 80 slices were affected, leading to poorer soft tissue delineation and reduced superior–inferior coverage. The proposed method effectively corrects those contaminated slices with mean intensity differences compared to FDK results decreasing from ∼497 and ∼293 HU to ∼39 and ∼27 HU for the full-fan and half-fan cases, respectively. In terms of efficiency boost

  14. Towards the clinical implementation of iterative low-dose cone-beam CT reconstruction in image-guided radiation therapy: Cone/ring artifact correction and multiple GPU implementation

    PubMed Central

    Yan, Hao; Wang, Xiaoyu; Shi, Feng; Bai, Ti; Folkerts, Michael; Cervino, Laura; Jiang, Steve B.; Jia, Xun

    2014-01-01

    Purpose: Compressed sensing (CS)-based iterative reconstruction (IR) techniques are able to reconstruct cone-beam CT (CBCT) images from undersampled noisy data, allowing for imaging dose reduction. However, there are a few practical concerns preventing the clinical implementation of these techniques. On the image quality side, data truncation along the superior–inferior direction under the cone-beam geometry produces severe cone artifacts in the reconstructed images. Ring artifacts are also seen in the half-fan scan mode. On the reconstruction efficiency side, the long computation time hinders clinical use in image-guided radiation therapy (IGRT). Methods: Image quality improvement methods are proposed to mitigate the cone and ring image artifacts in IR. The basic idea is to use weighting factors in the IR data fidelity term to improve projection data consistency with the reconstructed volume. In order to improve the computational efficiency, a multiple graphics processing units (GPUs)-based CS-IR system was developed. The parallelization scheme, detailed analyses of computation time at each step, their relationship with image resolution, and the acceleration factors were studied. The whole system was evaluated in various phantom and patient cases. Results: Ring artifacts can be mitigated by properly designing a weighting factor as a function of the spatial location on the detector. As for the cone artifact, without applying a correction method, it contaminated 13 out of 80 slices in a head-neck case (full-fan). Contamination was even more severe in a pelvis case under half-fan mode, where 36 out of 80 slices were affected, leading to poorer soft tissue delineation and reduced superior–inferior coverage. The proposed method effectively corrects those contaminated slices with mean intensity differences compared to FDK results decreasing from ∼497 and ∼293 HU to ∼39 and ∼27 HU for the full-fan and half-fan cases, respectively. In terms of efficiency boost

  15. Saturn's Other Ring Current

    NASA Astrophysics Data System (ADS)

    Crary, F. J.

    2014-04-01

    Saturn's main rings orbit the planet within an atmosphere and ionosphere of water, oxygen and hydrogen, produced by meteoritic impacts on and ultraviolet photodesorbtion of the ring particles [Johnson et al., 2006; Luhmann et al., 2006; Tseng et al., 2010]. The neutral atmosphere itself has only been tentatively detected through ultraviolet fluorescents of OH [Hall et al., 1996] while the ionosphere was observed in situ by the Cassini spacecraft shortly after orbital insertion [Coates et al.,2005; Tokar et al. 2005, Waite et al. 2005]. Although the plasma flow velocity of this ionosphere is not well-constrained, but the close association with the rings suggests that its speed would be couppled to the keplarian velocity of the rings themselves. As a result, the motion of the plasma through Saturn's magnetic field would produce an induced voltage, oriented away from the planet outside synchronous orbit and towards the planet inside synchronous orbit. Such a potential could result in currents flowing across the ring plane and closeing along magnetic field lines and through Saturn's ionosphere at latitudes between 36o and 48o. Cassini observations of whistler-mode plasma wave emissions [Xin et al.,2006] centered on synchronous orbit (1.76 Rs, mapping to 41o latitude) have been interpreted as a product of field-aligned electron beams associated with such a current. This presentation will investigate the magnitude of these currents and the resulting Joule heating of the ionosphere. An important constraint is that no auroral ultraviolet emissions have been observed at the relevant latitudes. In contrast, Joule heating could affect infrared emissions from H3+. Variations in H3+ emission associated with Saturn's rings have been reported by O'Donoghue et al., 2013, and interpreted as a result of ring "rain", i.e. precipitating water group species from the rings which alter ionosphereic chemistry and H3+ densities. As noted by O'Donoghue et al., this interpretation may be

  16. Status of the SNS Ring Power Ramp UP

    SciTech Connect

    Plum, Michael A; Aleksandrov, Alexander V; Allen, Christopher K; Cousineau, Sarah M; Danilov, Viatcheslav; Galambos, John D; Holmes, Jeffrey A; Jeon, Dong-O; Pelaia II, Tom; Shishlo, Andrei P; Zhang, Yan

    2008-01-01

    Beam was first circulated in the Spallation Neutron Source (SNS) ring in January 2006. Since that time we have been working to raise the beam power to the design value of 1.4 MW. In general the power ramp up has been proceeding very well, but several issues have been uncovered. Examples include poor transmission of the waste beams in the injection dump beam line, and cross-plane coupling in the ring to target beam transport line. In this paper we will discuss these issues and present an overall status of the ring and the transport beam lines.

  17. Energy compensation of slow extracted beams with RF acceleration

    NASA Astrophysics Data System (ADS)

    Fujimoto, Tetsuya; Souda, Hikaru; Torikoshi, Masami; Kanai, Tatsuaki; Yamada, Satoru; Noda, Koji

    2016-03-01

    In a conventional carbon-ion radiotherapy facility, a carbon-ion beam is typically accelerated up to an optimum energy, slowly extracted from a synchrotron ring by a resonant slow extraction method, and ultimately delivered to a patient through a beam-delivery system. At Japan's Gunma University, a method employing slow-beam extraction along with beam-acceleration has been adopted. This method slightly alters the extracted-beam's energy owing to the acceleration component of the process, which subsequently results in a residual-range variation of approximately 2 mm in water-equivalent length. However, this range variation does not disturb a distal dose distribution with broad-beam methods such as the single beam-wobbling method. With the pencil-beam 3D scanning method, however, such a range variation disturbs a distal dose distribution because the variation is comparable to slice thickness. Therefore, for pencil-beam 3D scanning, an energy compensation method for a slow extracted beam is proposed in this paper. This method can compensate for the aforementioned energy variances by controlling net energy losses through a rotatable energy absorber set fixed between the synchrotron exit channel and the isocenter. Experimental results demonstrate that beam energies can be maintained constant, as originally hypothesized. Moreover, energy-absorber positions were found to be significantly enhanced by optimizing beam optics for reducing beam-size growth by implementation of the multiple-scattering effect option.

  18. Local compensation-rematch for major element failures in superconducting linacs with very high reliability and low beam loss

    NASA Astrophysics Data System (ADS)

    Sun, Biao; Tang, Jingyu; Yan, Fang; Li, Zhihui; Meng, Cai; Pei, Shilun

    2015-06-01

    In order to achieve the extremely high reliability and availability in superconducting linacs required by some applications such as in accelerator-driven systems (ADS), a fault tolerance design is usually pursued. With the example of the China-ADS main linac, the failure effects of key elements such as RF cavities and focusing elements in different locations along the linac have been studied and the schemes of compensation by means of the local compensation-rematch method have been proposed. For cavity failures, by adjusting the settings of the neighboring cavities and focusing elements one can make sure that the Twiss parameters and beam energy are recovered to the nominal ones at the matching point. For solenoid failures in the low energy section, a novel method by using a neighbor cavity with reverse phase is used to maintain simultaneous acceleration and focusing in both the transverse and longitudinal phase planes. For quadrupole failures in the warm transitions in the high energy section, triplet focusing structure is adopted which can be converted locally into a doublet focusing in case of one quadrupole failure and the rematch method is proven very effective. With macro-particle simulations by TraceWin, it is found that the normalized rms emittance has no obvious growth and the halo emittance has modest growth after applying the local compensation-rematch in the cases mentioned above. In addition, a self-made code based on MATLAB has been developed to double check the simulations by TraceWin for the local compensation and rematch method.

  19. MUON STORAGE RINGS - NEUTRINO FACTORIES

    SciTech Connect

    PARSA,Z.

    2000-05-30

    The concept of a muon storage ring based Neutrino Source (Neutrino Factory) has sparked considerable interest in the High Energy Physics community. Besides providing a first phase of a muon collider facility, it would generate more intense and well collimated neutrino beams than currently available. The BNL-AGS or some other proton driver would provide an intense proton beam that hits a target, produces pions that decay into muons. The muons must be cooled, accelerated and injected into a storage ring with a long straight section where they decay. The decays occurring in the straight sections of the ring would generate neutrino beams that could be directed to detectors located thousands of kilometers away, allowing studies of neutrino oscillations with precisions not currently accessible. For example, with the neutrino source at BNL, detectors at Soudan, Minnesota (1,715 km), and Gran Sasso, Italy (6,527 km) become very interesting possibilities. The feasibility of constructing and operating such a muon-storage-ring based Neutrino-Factory, including geotechnical questions related to building non-planar storage rings (e.g. at 8{degree} angle for BNL-Soudan, and 3{degree} angle for BNL-Gran Sasso) along with the design of the muon capture, cooling, acceleration, and storage ring for such a facility is being explored by the growing Neutrino Factory and Muon Collider Collaboration (NFMCC). The authors present overview of Neutrino Factory concept based on a muon storage ring, its components, physics opportunities, possible upgrade to a full muon collider, latest simulations of front-end, and a new bowtie-muon storage ring design.

  20. Oxidation study by Auger electron spectroscopy and electron energy-loss spectroscopy of GaSb(001) surfaces grown by molecular-beam epitaxy

    SciTech Connect

    Raisin, C.; Da Silva, F.W.O.; Lassabatere, L. , Place Eugene Bataillon, 34095 Montpellier-Cedex 5, France )

    1990-01-01

    GaSb (001) surfaces were prepared by molecular-beam epitaxy. Auger electron spectroscopy (AES) and electron energy-loss spectroscopy (EELS) are reported for clean surfaces exposed to oxygen, and during the process the ionization gauge of the vacuum system is turned on. Successive stages of chemisorption can be distinguished. For oxygen coverage up to 0.5 monolayer, the surface states are saturated by bonding of the oxygen with Ga and Sb atoms. Sb atoms desorb causing significant Sb depletion in the first layer. Larger exposures further increase the coverage and induce, in the EELS spectra, losses related to O(2{ital p}) and O(2{ital s}) atomic states and new plasmon excitations. In the AES spectra the shift of Auger emission lines which are characteristic of Sb and Ga oxide forms appear; at coverages of about one monolayer back bonds break forming Sb{sub 2}O{sub 3} and Ga{sub 2}O{sub 3}. Further exposures to oxygen result in thicker oxide layers of Ga and Sb.

  1. Beam injection into RHIC

    SciTech Connect

    Fischer, W.; Hahn, H.; MacKay, W.W.; Satogata, T.; Tsoupas, N.; Zhang, W.

    1997-07-01

    During the RHIC sextant test in January 1997 beam was injected into a sixth of one of the rings for the first time. The authors describe the injection zone and its bottlenecks. They report on the commissioning of the injection system, on beam based measurements of the kickers and the application program to steer the beam.

  2. Recent Progress on Design Studies of High-Luminosity Ring-Ring Electron-Ion Collider at CEBAF

    SciTech Connect

    Zhang, Y; Bruell, A; Chevtsov, P; Derbenev, Y S; Ent, R; Krafft, G A; Li, R; Merminga, L; Yunn, B C

    2009-05-01

    The conceptual design of a ring-ring electron-ion collider based on CEBAF has been continuously optimized to cover a wide center-of-mass energy region and to achieve high luminosity and polarization to support next generation nuclear science programs. Here, we summarize the recent design improvements and R&D progress on interaction region optics with chromatic aberration compensation, matching and tracking of electron polarization in the Figure-8 ring, beam-beam simulations and ion beam cooling studies.

  3. Potential for the measurement of the tensor electric and magnetic polarizabilities of the deuteron in storage-ring experiments with polarized beams

    NASA Astrophysics Data System (ADS)

    Baryshevsky, V. G.; Silenko, A. J.

    2011-05-01

    The measurement of the tensor electric and magnetic polarizabilities of the deuteron is of great interest, especially in connection with the possibilities of COSY and GSI. These polarizabilities can be measured in storage rings by the frozen spin method providing a disappearance of g - 2 precession. This method will be used in the planned deuteron electric-dipole-moment experiment in storage rings. The tensor electric polarizability of the deuteron significantly influences the buildup of the vertical polarization in the above experiment. The spin interactions depending on the electric dipole moment, the tensor electric polarizability, and main systematical errors caused by field misalignments have very different symmetries. For the considered experimental conditions, the sensitivity to the deuteron EDM of 1 × 10-29 e·cm corresponds to measuring both tensor polarizabilities with an accuracy δαT ≈ δβT ≈ 5 × 10-42 cm3. This conservative estimate can be improved by excluding the systematical error caused by the field instability which is negligible for the measurement of the tensor polarizabilities. In order to determine the tensor magnetic polarizability, the horizontal components of the polarization vector should be measured.

  4. Ring Galaxies

    NASA Astrophysics Data System (ADS)

    Dennefeld, M.; Materne, J.

    1980-09-01

    Among the 338 exotic, intriguing and/or fascinating objects contained in Arp's catalogue of peculiar galaxies, two, Arp 146 and 147, are calling special attention as a presumably separate class of objects displaying closed rings with almost empty interior. It is difficult to find out when, historically speaking, attention was called first to this type of object as a peculiar class, but certainly ga1axies with rings were widely found and recognized in the early sixties, ul}der others by Vorontsov-Velyaminov (1960), Sandage (1961) in the Hubble Atlas or de Vaucouleurs (1964) in the first reference catalogue of ga1axies. The most recent estimates by Arp and Madore (1977) from a search on about 200 Schmidt plates covering 7,000 square degrees give 3.6 per cent of ring galaxies among 2,784 peculiar galaxies found. However, despite the mythological perfection associated with a circle, some ordering is necessary before trying to understand the nature of such objects. This is particularly true because a large fraction of those galaxies with rings are probably normal spiral galaxies of type RS or S(r) as defined by de Vaucouleurs, where the spiral arms are simply "closing the circle". A good example of such "ordinary" galaxy is NGC 3081 in the Hubble Atlas .

  5. The cryogenic storage ring CSR.

    PubMed

    von Hahn, R; Becker, A; Berg, F; Blaum, K; Breitenfeldt, C; Fadil, H; Fellenberger, F; Froese, M; George, S; Göck, J; Grieser, M; Grussie, F; Guerin, E A; Heber, O; Herwig, P; Karthein, J; Krantz, C; Kreckel, H; Lange, M; Laux, F; Lohmann, S; Menk, S; Meyer, C; Mishra, P M; Novotný, O; O'Connor, A P; Orlov, D A; Rappaport, M L; Repnow, R; Saurabh, S; Schippers, S; Schröter, C D; Schwalm, D; Schweikhard, L; Sieber, T; Shornikov, A; Spruck, K; Sunil Kumar, S; Ullrich, J; Urbain, X; Vogel, S; Wilhelm, P; Wolf, A; Zajfman, D

    2016-06-01

    An electrostatic cryogenic storage ring, CSR, for beams of anions and cations with up to 300 keV kinetic energy per unit charge has been designed, constructed, and put into operation. With a circumference of 35 m, the ion-beam vacuum chambers and all beam optics are in a cryostat and cooled by a closed-cycle liquid helium system. At temperatures as low as (5.5 ± 1) K inside the ring, storage time constants of several minutes up to almost an hour were observed for atomic and molecular, anion and cation beams at an energy of 60 keV. The ion-beam intensity, energy-dependent closed-orbit shifts (dispersion), and the focusing properties of the machine were studied by a system of capacitive pickups. The Schottky-noise spectrum of the stored ions revealed a broadening of the momentum distribution on a time scale of 1000 s. Photodetachment of stored anions was used in the beam lifetime measurements. The detachment rate by anion collisions with residual-gas molecules was found to be extremely low. A residual-gas density below 140 cm(-3) is derived, equivalent to a room-temperature pressure below 10(-14) mbar. Fast atomic, molecular, and cluster ion beams stored for long periods of time in a cryogenic environment will allow experiments on collision- and radiation-induced fragmentation processes of ions in known internal quantum states with merged and crossed photon and particle beams. PMID:27370434

  6. The cryogenic storage ring CSR

    NASA Astrophysics Data System (ADS)

    von Hahn, R.; Becker, A.; Berg, F.; Blaum, K.; Breitenfeldt, C.; Fadil, H.; Fellenberger, F.; Froese, M.; George, S.; Göck, J.; Grieser, M.; Grussie, F.; Guerin, E. A.; Heber, O.; Herwig, P.; Karthein, J.; Krantz, C.; Kreckel, H.; Lange, M.; Laux, F.; Lohmann, S.; Menk, S.; Meyer, C.; Mishra, P. M.; Novotný, O.; O'Connor, A. P.; Orlov, D. A.; Rappaport, M. L.; Repnow, R.; Saurabh, S.; Schippers, S.; Schröter, C. D.; Schwalm, D.; Schweikhard, L.; Sieber, T.; Shornikov, A.; Spruck, K.; Sunil Kumar, S.; Ullrich, J.; Urbain, X.; Vogel, S.; Wilhelm, P.; Wolf, A.; Zajfman, D.

    2016-06-01

    An electrostatic cryogenic storage ring, CSR, for beams of anions and cations with up to 300 keV kinetic energy per unit charge has been designed, constructed, and put into operation. With a circumference of 35 m, the ion-beam vacuum chambers and all beam optics are in a cryostat and cooled by a closed-cycle liquid helium system. At temperatures as low as (5.5 ± 1) K inside the ring, storage time constants of several minutes up to almost an hour were observed for atomic and molecular, anion and cation beams at an energy of 60 keV. The ion-beam intensity, energy-dependent closed-orbit shifts (dispersion), and the focusing properties of the machine were studied by a system of capacitive pickups. The Schottky-noise spectrum of the stored ions revealed a broadening of the momentum distribution on a time scale of 1000 s. Photodetachment of stored anions was used in the beam lifetime measurements. The detachment rate by anion collisions with residual-gas molecules was found to be extremely low. A residual-gas density below 140 cm-3 is derived, equivalent to a room-temperature pressure below 10-14 mbar. Fast atomic, molecular, and cluster ion beams stored for long periods of time in a cryogenic environment will allow experiments on collision- and radiation-induced fragmentation processes of ions in known internal quantum states with merged and crossed photon and particle beams.

  7. Nonreciprocal gain control for ring laser

    NASA Technical Reports Server (NTRS)

    Dueker, G.; Lee, P.

    1967-01-01

    Nonreciprocal gain control is used in a ring laser where the two contracirculating beams may have differing intensities because of the residual Faraday rotation and other secondary nonreciprocal effects.

  8. INSTABILITY ISSUES AT THE SNS STORAGE RING

    SciTech Connect

    ZHANG,S.Y.

    1999-06-28

    The impedance and beam instability issues of the SNS storage ring is reviewed, and the effort toward solutions at the BNL is reported. Some unsettled issues are raised, indicating the direction of planned works.

  9. Laser cooling of a stored ion beam: A first step towards crystalline beams

    SciTech Connect

    Hangst, J.S.

    1992-09-01

    This report discusses: a brief introduction to storage rings; crystalline beams; laser cooling of ion beams; description of astrid-the experimental setup; first experiments with lithium 7 ion beam; experiments with erbium 166 ion beams; further experiments with lithium 7 ion beams; beam dynamics, laser cooling,and crystalline beams in astrid; possibilities for further study in astrid.

  10. COLLECTIVE EFFECTS AND THEIR CONTROL AT THE SPALLATION NEUTRON SOURCE RING.

    SciTech Connect

    WEI,J.; BLASKIEWICZ,M.; BRODOWSKI,J.; CAMERON,P.; DAVINO,D.; FEDOTOV,A.; HAHAN,H.; HSEUH,H.; LEE,Y.Y.; RAPARIA,D.; ZHANG,S.Y.; ET AL

    2002-06-03

    One of the primary tasks in the design of the Spallation Neutron Source (SNS) ring is to control collective effects including space charge, transverse and longitudinal instabilities, and electron cloud. Transverse painting is used to alleviate space charge force; longitudinal painting along with chromatic sextupoles are used to enhance Landau damping; injection kicker vacuum pipes are carefully shielded, and extraction kicker impedances are measured in detail and optimized; beam halo, beam loss and electron production are minimized; finally, damping systems at various frequencies are planned. This paper summarizes these design implementations.

  11. Electron Cloud Generation and Trapping in a Quadrupole Magnet at the Los Alamos Proton Storage Ring

    SciTech Connect

    Macek, Robert J.; Browman, Andrew A.; Ledford, John E.; Borden, Michael J.; O'Hara, James F.; McCrady, Rodney C.; Rybarcyk, Lawrence J.; Spickermann, Thomas; Zaugg, Thomas J.; Pivi, Mauro T.F.; /SLAC

    2008-03-17

    Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR) have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the 'prompt' electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the 'swept' electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100 {micro}s. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole.

  12. Latest on polarization in electron storage rings

    SciTech Connect

    Chao, A.W.

    1983-01-01

    The field of beam polarization in electron storage rings is making rapid progress in recent several years. This report is an attempt to summarize some of these developments concerning how to produce and maintain a high level of beam polarization. Emphasized will be the ideas and current thoughts people have on what should and could be done on electron rings being designed at present such as HERA, LEP and TRISTAN. 23 references.

  13. Monitoring Dosimetric Impact of Weight Loss With Kilovoltage (KV) Cone Beam CT (CBCT) During Parotid-Sparing IMRT and Concurrent Chemotherapy

    SciTech Connect

    Ho, Kean Fatt; Marchant, Tom; Moore, Chris; Webster, Gareth; Rowbottom, Carl; Penington, Hazel; Lee, Lip; Yap, Beng; Sykes, Andrew; Slevin, Nick

    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

  14. Wavelength-tunable optical ring resonators

    DOEpatents

    Watts, Michael R.; Trotter, Douglas C.; Young, Ralph W.; Nielson, Gregory N.

    2009-11-10

    Optical ring resonator devices are disclosed that can be used for optical filtering, modulation or switching, or for use as photodetectors or sensors. These devices can be formed as microdisk ring resonators, or as open-ring resonators with an optical waveguide having a width that varies adiabatically. Electrical and mechanical connections to the open-ring resonators are made near a maximum width of the optical waveguide to minimize losses and thereby provide a high resonator Q. The ring resonators can be tuned using an integral electrical heater, or an integral semiconductor junction.

  15. Wavelength-tunable optical ring resonators

    DOEpatents

    Watts, Michael R.; Trotter, Douglas C.; Young, Ralph W.; Nielson, Gregory N.

    2011-07-19

    Optical ring resonator devices are disclosed that can be used for optical filtering, modulation or switching, or for use as photodetectors or sensors. These devices can be formed as microdisk ring resonators, or as open-ring resonators with an optical waveguide having a width that varies adiabatically. Electrical and mechanical connections to the open-ring resonators are made near a maximum width of the optical waveguide to minimize losses and thereby provide a high resonator Q. The ring resonators can be tuned using an integral electrical heater, or an integral semiconductor junction.

  16. Effect of beam expansion loss in a carbon nanotube-doped PVA film on passively mode-locked erbium-doped fiber lasers with different feedback ratios

    NASA Astrophysics Data System (ADS)

    Cheng, Kuang-Nan; Chi, Yu-Chieh; Cheng, Chih-Hsien; Lin, Yung-Hsiang; Lo, Jui-Yung; Lin, Gong-Ru

    2014-10-01

    The effect of beam expansion induced divergent loss in a single-wall carbon nanotube (SWCNT) doped polyvinyl alcohol (PVA) based ultrafast saturable absorber (SA) film thickness on the passive mode-locking (PML) performances of erbium-doped fiber lasers are demonstrated. The variation on the PML pulsewidth of the EDFL is discussed by changing the SWCNT-PVA SA film thicknesses, together with adjusting the pumping power and the intra-cavity feedback ratio. An almost 6 dB increment of divergent loss when enlarging the SWCNT-PVA based SA film thickness from 30-130 µm is observed. When shrinking the SA thickness to 30 µm at the largest pumping power of 52.5 mW, the optical spectrum red-shifts to 1558.8 nm with its 3 dB spectral linewidth broadening up to 2.7 nm, while the pulse has already entered the soliton regime with multi-order Kelly sidebands aside the spectral shoulder. The soliton pulsewidth is as short as 790 fs, which is much shorter than those obtained with other thicker SWCNT doped PVA polymer film based SAs; therefore, the peak power from the output of the PML-EDFL is significantly enlarged accompanied by a completely suppressed residual continuous-wave level to achieve the largest on/off extinction ratio. The main mechanism of pulse shortening with reducing thickness of SWCNT doped PVA polymer film based SA is attributed to the limited beam expansion as well as the enlarged modulation depth, which results in shortened soliton pulsewidth with a clean dc background, and broadened spectrum with enriched Kelly sidebands. The increase of total SWCNT amount in the thicker SA inevitably causes a higher linear absorption; hence, the mode-locking threshold also rises accordingly. By enlarging pumping power from 38.5-52.5 mW, the highest ascent on pulse extinction of up to 32 dB is observed among all kinds of feedback conditions. Nevertheless, the enlargement on the extinction slightly decays with increasing the feedback ratio from 30-90%, as

  17. Cone beam computed tomographic analysis of maxillary premolars and molars to detect the relationship between periapical and marginal bone loss and mucosal thickness of maxillary sinus

    PubMed Central

    Sekerci, Ahmet-Ercan; Köse, Emre; Sisman, Yildiray

    2015-01-01

    Background This study assessed the relationship between mucosal thickness (MT) of the maxillary sinus and periodontal bone loss (PBL) and periapical condition of related teeth. We also aimed to identify the association between root apices and the inferior wall of the maxillary sinus using Cone beam computed tomography (CBCT). Material and Methods In this study, CBCT images of 205 patients with 410 maxillary sinuses were examined, retrospectively. A total of 582 maxillary molars and 587 premolars were observed. The relationship of each root with maxillary sinus and apical lesions of these roots were classified, PBL was examined and the situations of adjacent teeth were estimated. The effect of these conditions on sinus mucosal thickness (MT) was evaluated. Results There was a significant correlation between MT of maxillary sinus and both PBL and age (r = 0.52, p=0.000 and r = 0.111, p= 0.002, respectively). The frequency of MT increased as the severity of apical lesion enlarged. A positive correlation was found between MT and degree of PBL and periapical lesions. To reveal the association between MT and pulpoperiapical condition bivariate correlation was done and a significant relationship between the pulpoperiapical condition and MT was found (r = 0.17, p=0.000). Conclusions This retrospective study showed that MT of the maxillary sinus was common among patients with PBL and MT was significantly associated with PBL and apical lesions. The relationship of maxillary sinus to adjacent teeth had also positive correlation with MT. CBCT imaging enabled better evaluation of maxillary sinus, posterior teeth and surrounding structures compared to other imaging tools. Key words:Maxillary sinus mucosal thickness, apical periodontitis, periodontal bone loss, CBCT. PMID:26241459

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

    SciTech Connect

    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.

  19. Transport from the Recycler Ring to the Antiproton Source Beamlines

    SciTech Connect

    Xiao, M.; /Fermilab

    2012-05-14

    In the post-NOvA era, the protons are directly transported from the Booster ring to the Recycler ring rather than the Main Injector. For Mu2e and g-2 project, the Debuncher ring will be modified into a Delivery ring to deliver the protons to both Mu2e and g-2 experiments. Therefore, it requires the transport of protons from the Recycler Ring to the Delivery ring. A new transfer line from the Recycler ring to the P1 beamline will be constructed to transport proton beam from the Recycler Ring to existing Antiproton Source beamlines. This new beamline provides a way to deliver 8 GeV kinetic energy protons from the Booster to the Delivery ring, via the Recycler, using existing beam transport lines, and without the need for new civil construction. This paper presents the Conceptual Design of this new beamline.

  20. Quasi-static thermoelastic analysis for a semi-infinite plane subjected to a Gaussian heat source: Beam missteering of the storage ring in the APS

    SciTech Connect

    Sheng, I.C.; Howell, J.

    1995-07-01

    A two-dimensional, semi-infinite analytical solution of the transient temperature and the thermal stress due to heating from the bending magnet beam missteering in the APS has been developed. In order to solve the thermal stress analytically, an effective absorption function is introduced, and the transient temperature can be written as a function of the exponential integrals. At the origin where the peak power is applied, the effective stress is found to be the maximum and is undergoing simple compression along the longitudinal direction. The result utilizing finite element method (FEM) applied to the chamber cross section is also presented and agrees fairly well with the current analytical solution during the early small time scale.

  1. MARS14 Collimation and Shielding Studies for the 3 GeV Ring of J-PARC Project

    NASA Astrophysics Data System (ADS)

    Nakao, Noriaki; Mokhov, Nikolai; Yamamoto, Kazami; Irie, Yoshiro; Drozhdin, Alexander

    2003-12-01

    MARS14 Monte Carlo simulations were performed for collimation and shielding studies of the J-PARC 3 GeV ring. A 400 MeV proton beam loss distribution, calculated with the STRUCT code, was used as a source term. The module locations in the ring and the curved tunnel sections were described by the MAD-MARS beam line builder and a deep penetration calculation with good statistics was carried out using a 3-dimensional multi-layer technique. Prompt dose-rate distributions were calculated inside and outside the concrete and soil shield, and an effective shielding design was made. The residual dose rates for various beam line materials were also calculated to estimate the external-exposures during maintenance. In this paper, the calculation results are exemplified for the region from the injection through the collimator.

  2. Injection seeded, diode pumped regenerative ring Nd:YAG amplifier for spaceborne laser ranging technology development

    NASA Technical Reports Server (NTRS)

    Coyle, D. Barry; Kay, Richard B.; Degnan, John J.; Krebs, Danny J.; Seery, Bernard D.

    1992-01-01

    A small, all solid state, regenerative ring amplifier designed as a prototype for space application is discussed. Novel features include dual side pumping of the Nd:YAG crystal and a triangular ring cavity design which minimizes the number of optical components and losses. The amplifier is relatively small (3 ns round trip time) even though standard optical elements are employed. The ring regeneratively amplifies a 100 ps single pulse by approximately 10(exp 5) at a repetition rate of 10 to 100 Hz. The amplifier is designed to be injection seeded with a pulsed, 100 ps laser diode at 1.06 microns, but another Nd:YAG laser system supplying higher pulse energies was employed for laboratory experiment. This system is a prototype laser oscillator for the Geoscience Laser Ranging System (GLRS) platform. Results on measurements of beam quality, astigmatism, and gain are given.

  3. Ringing wormholes

    SciTech Connect

    Konoplya, R.A.; Molina, C.

    2005-06-15

    We investigate the response of traversable wormholes to external perturbations through finding their characteristic frequencies and time-domain profiles. The considered solution describes traversable wormholes between the branes in the two brane Randall-Sundrum model and was previously found within Einstein gravity with a conformally coupled scalar field. The evolution of perturbations of a wormhole is similar to that of a black hole and represents damped oscillations (ringing) at intermediately late times, which are suppressed by power-law tails (proportional to t{sup -2} for monopole perturbations) at asymptotically late times.

  4. The performance of the Los Alamos Proton Storage Ring

    SciTech Connect

    Lawrence, G.P.

    1987-03-01

    The Proton Storage Ring (PSR) now in operation at Los Alamos is a high-current accumulator that generates intense 800-MeV proton pulses for driving the Los Alamos Neutron Scattering Center (LANSCE) spallation source. The ring compresses up to 1000-..mu..s-long macropulses from the LAMPF linac into 250-ns bunches and ejects them to a neutron-production target, providing an output optimized for thermal-neutron-scattering research. The design pulse rate and peak pulse intensity of PSR are 12 Hz and 5.2 . 10/sup 13/ protons per pulse (ppp), yielding 100 ..mu..A average current when full performance is reached. This paper summarizes commissioning results and operational experience in the two years since first beam. The PSR has operated in production at average currents up to 30 ..mu..A and has reached a peak intensity of 3.4 . 10/sup 13/ ppp. These achievements represents 30% and 65% of the design objectives. Higher current production has been inhibited by beam losses during accumulation and extraction. Therefore, experiments to understand loss mechanisms have occupied a large fraction of the commissioning effort. Correction of an extraction-channel aperture restriction identified late in 1986 should dramatically reduce extraction losses, which will permit higher current production in 1987. Beam tests in the 10/sup 13/-ppp range have indicated the presence of a collective instability tentatively identified as transverse. However, by suitable parameter adjustments, the instability threshold can be pushed above the top charge-level attainable with the existing H /sup -/ source.

  5. Cure of Coupled Bunch Instabilities in PLS Storage Ring

    SciTech Connect

    Fox, John D

    2003-04-24

    The Pohang Light Source (PLS) storage ring whose design emittance is 12-nm uses four 500 MHz nosecone-structure rf cavities to store beam current up to 400-mA at 2-GeV. The stored beam current was limited to 180-mA at 2-GeV because of the coupled bunch instabilities (CBI) excited by higher order modes (HOMs) of rf cavity. In order to cure the CBIs three measures are incorporated: HOM frequency tuning by cavity temperature adjustment; a longitudinal feedback system (LFS); a transverse feedback system (TFS). Growth rate of longitudinal and transverse HOMs of all rf cavities as a function of cavity temperature was estimated with the low-power measurement data of frequency shift, and confirmed with the BPM amplitude of CBMs. The LFS which uses programmable digital signal processors supplied by SLAC was successfully commissioned at the end of 1999, and a very stable and low emittance electron beam could be stored up to 230-mA over which transverse CBIs grow severely and drive to beam loss. After completion of TFS at the beginning of 2000 we will be able to cure all CBIs by LFS and TFS, and store beam current higher than 300-mA.

  6. The University of Maryland Electron Ring Program

    NASA Astrophysics Data System (ADS)

    Kishek, R. A.; Beaudoin, B. L.; Bernal, S.; Cornacchia, M.; Feldman, D.; Fiorito, R.; Haber, I.; Koeth, T.; Mo, Y. C.; O'Shea, P. G.; Rezaei, K. Poor; Sutter, D.; Zhang, H. D.

    2014-01-01

    The University of Maryland Electron Ring (UMER) is a unique machine that uses scaled electron beams at nonrelativistic energies (10 keV) to inexpensively model GeV beams of heavy ions over long path lengths (kilometers of transport distance). The UMER beam parameters correspond to space charge tune depressions, at injection, adjustable in the range of 0.14-0.85. Although a ring, many of the intense beam studies on UMER are applicable to linacs. This paper reviews the UMER program, which contains experimental, computational, and theoretical components. We outline the research areas of interest, recent accomplishments, and future plans, emphasizing the relevance to heavy ion drivers. Specific topics include longitudinal induction focusing and beam manipulations; generation and propagation of space charge waves, including large-amplitude solitons; bunch end interpenetration and observation of a multi-stream instability; beam halo studies; and diagnostic development.

  7. The Effect of Gas Ion Bombardment on the Secondary Electron Yield of TiN, TiCN and TiZrV Coatings For Suppressing Collective Electron Effects in Storage Rings

    SciTech Connect

    Le Pimpec, F.; Kirby, R.E.; King, F.K.; Pivi, M.; /SLAC

    2006-01-25

    In many accelerator storage rings running positively charged beams, ionization of residual gas and secondary electron emission (SEE) in the beam pipe will give rise to an electron cloud which can cause beam blow-up or loss of the circulating beam. A preventative measure that suppresses electron cloud formation is to ensure that the vacuum wall has a low secondary emission yield (SEY). The SEY of thin films of TiN, sputter deposited Non-Evaporable Getters and a novel TiCN alloy were measured under a variety of conditions, including the effect of re-contamination from residual gas.

  8. Geant4 simulation of the PSI LEM beam line: energy loss and muonium formation in thin foils and the impact of unmoderated muons on the μSR spectrometer

    NASA Astrophysics Data System (ADS)

    Khaw, K. S.; Antognini, A.; Crivelli, P.; Kirch, K.; Morenzoni, E.; Salman, Z.; Suter, A.; Prokscha, T.

    2015-10-01

    The PSI low-energy μSR spectrometer is an instrument dedicated to muon spin rotation and relaxation measurements. Knowledge of the muon beam parameters such as spatial, kinetic energy and arrival-time distributions at the sample position are important ingredients to analyze the μSR spectra. We present here the measured energy losses in the thin carbon foil of the muon start detector deduced from time-of-flight measurements. Muonium formation in the thin carbon foil (10 nm thickness) of the muon start detector also affect the measurable decay asymmetry and therefore need to be accounted for. Muonium formation and energy losses in the start detector, whose relevance increase with decreasing muon implantation energy (<10 keV), have been implemented in Geant4 Monte Carlo simulation to reproduce the measured time-of-flight spectra. Simulated and measured time-of-flight and beam spot agrees only if a small fraction of so called ``unmoderated'' muons which contaminate the mono-energetic muon beam of the μSR spectrometer is introduced. Moreover the sensitivity of the beam size and related upstream-downstream asymmetry for a specially shaped ``nose'' sample plate has been studied for various beam line settings, which is of relevance for the study of thermal muonium emission into vacuum from mesoporous silica at cryogenic temperatures.

  9. Lattice Design of the VLHC Rings

    SciTech Connect

    John A. Johnstone et al.

    2001-07-12

    The Very Large Hadron Collider (VLHC) is comprised of 2 rings, each having a 233 km circumference. the high-field (HF) ring is characterized by 90{degree} FODO cells constructed from separated-function magnets and vertical beam separation. the low-field (LF) accelerator is also constructed from separated-function magnets and vertical beam separation. The low-field (LF) accelerator is also constructed from 90{degree} cell, but these employ combined function transmission line magnets and horizontally separated beams. The optics of the 2 rings are virtually identical. The HF machine operates in the synchrotron radiation dominated regime. Doublet final focusing is employed to take advantage of the flat beam optics.

  10. Antiproton chain of the FAIR storage rings

    NASA Astrophysics Data System (ADS)

    Katayama, T.; Kamerdzhiev, V.; Lehrach, A.; Maier, R.; Prasuhn, D.; Stassen, R.; Stockhorst, H.; Herfurth, F.; Lestinsky, M.; Litvinov, Yu A.; Steck, M.; Stöhlker, T.

    2015-11-01

    In the Modularized Start Version of the Facility of Antiproton and Ion Research (FAIR) at Darmstadt Germany, the 3 GeV antiprotons are precooled in the collector ring and accumulated in the high energy storage ring (HESR). They are further accelerated to 14 GeV or decelerated to 1 GeV for the experiments with a high-density internal target. The powerful beam cooling devices, stochastic cooling and electron cooling will support the provision of a high-resolution antiproton beam. The other option of FAIR is to prepare the low energy, 300 keV antiproton beam connecting the existing storage rings ESR and CRYRING with HESR. Beam physics issues related with these concepts are described.

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

    PubMed Central

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

    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 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. PMID:25191066

  12. Symmetric form-invariant dual Pearcey beams.

    PubMed

    Ren, Zhijun; Fan, Changjiang; Shi, Yile; Chen, Bo

    2016-08-01

    We introduce another type of Pearcey beam, namely, dual Pearcey (DP) beams, based on the Pearcey function of catastrophe theory. DP beams are experimentally generated by applying Fresnel diffraction of bright elliptic rings. Form-invariant Bessel distribution beams can be regarded as a special case of DP beams. Subsequently, the basic propagation characteristics of DP beams are identified. DP beams are the result of the interference of two half DP beams instead of two classical Pearcey beams. Moreover, we also verified that half DP beams (including special-case parabolic-like beams) generated by half elliptical rings (circular rings) are a new member of the family of form-invariant beams. PMID:27505650

  13. A microwave beam waveguide undulator for a brilliant above 100 keV photon source.

    SciTech Connect

    Kang, Y. W.

    1999-04-19

    For generation of photons above 100-keV with a magnetic field strength in the range 0.2-0.5 Tesla, an undulator wavelength {lambda}{sub u} shorter than 5 mm may be needed with beam in the Advanced Photon Source (APS) storage ring. A microwave beam waveguide undulator system has been investigated for generation of such light. The waveguide structure consists of two parallel reflector surfaces that can be derived from an elliptically cylindrical waveguide. The structure can support deflecting TE{sub m0} modes with very low microwave loss. A microwave ring resonator circuit employing the beam waveguide is considered to construct an undulator with the above requirement. Microwave properties of the beam waveguide structure have been investigated, and the design criteria for a microwave undulator are discussed.

  14. Common operation metrics for storage ring light sources

    NASA Astrophysics Data System (ADS)

    Lüdeke, A.; Bieler, M.; Farias, R. H. A.; Krecic, S.; Müller, R.; Pont, M.; Takao, M.

    2016-08-01

    Storage ring light sources aim for high operational reliability. Very often beam availability is used as an operation metric to measure the reliability. A survey of several light sources reveals that the calculation of availability varies significantly between facilities. This complicates useful comparisons of reliability. Furthermore the beam availability does not provide insight regarding reliability of beam characteristics such as orbit and beam size stability. The authors propose specific metrics to evaluate the reliability of storage ring light sources; these metrics allow a detailed and meaningful comparison across facilities. Such comparisons are useful to further optimize the reliability of storage ring light source facilities.

  15. Beam-beam interactions for bunched and unbunched beams

    SciTech Connect

    Courant, E D

    1980-01-01

    The beam-beam interaction is analyzed in terms of Chirikov's stochasticity model. Stochastic blow-up occurs when the density of resonance regions in phase space becomes large, and Arnold diffusion is assumed to depend on the density parameter below the stochastic threshold. The relation between the density parameter and the tune shift epsilon is affected by bunching of the beam and also by variations in the strengths of several interaction regions and by beam misalignment. It is seen that bunching can reduce the tolerable epsilon by as much as an order of magnitude in proton storage rings.

  16. Beam Injection into RHIC

    NASA Astrophysics Data System (ADS)

    Fischer, W.; Hahn, H.; Mackay, W. W.; Tsoupas, N.

    1997-05-01

    During the RHIC sextant test in January 1997 beam was injected into a sixth of one of the rings for the first time. We describe the injection zone and its bottlenecks, the application program to steer the beam and the injection kickers. We report on the commissioning of the injection systems and on measurements of the kickers.

  17. Collar nut and thrust ring

    DOEpatents

    Lowery, Guy B.

    1991-01-01

    A collar nut comprises a hollow cylinder having fine interior threads at one end for threadably engaging a pump mechanical seal assembly and an inwardly depending flange at the other end. The flange has an enlarged portion with a groove for receiving an O-ring for sealing against the intrusion of pumpage from the exterior. The enlarged portion engages a thrust ring about the pump shaft for crushing a hard O-ring, such as a graphite O-ring. The hard O-ring seals the interior of the mechanical seal assembly and pump housing against the loss of lubricants or leakage of pumpage. The fine threads of the hollow cylinder provide the mechanical advantage for crushing the hard O-ring evenly and easily with a hand tool from the side of the collar nut rather than by tightening a plurality of bolts from the end and streamlines the exterior surface of the mechanical seal. The collar nut avoids the spatial requirements of bolt heads at the end of a seal and associated bolt head turbulence.

  18. Development of the beam extraction synchronization system at the Fermilab Booster

    NASA Astrophysics Data System (ADS)

    Seiya, K.; Chaurize, S.; Drennan, C. C.; Pellico, W.; Sullivan, T.; Triplett, A. K.; Waller, A. M.

    2015-11-01

    The new beam extraction synchronization control system called "Magnetic Cogging" was developed at the Fermilab Booster and it replaces a system called "RF Cogging" as part of the Proton Improvement Plan (PIP).[1] The flux throughput goal for the PIP is 2.2×1017 protons per hour, which is double the present flux. The flux increase will be accomplished by doubling the number of beam cycles which, in turn, will double the beam loss in the Booster accelerator if nothing else is done. The Booster accelerates beam from 400 MeV to 8 GeV and extracts it to the Main Injector (MI) or Recycler Ring (RR). Cogging controls the beam extraction gap position which is created early in the Booster cycle and synchronizes the gap to the rising edge of the Booster extraction kicker and the MI/RR injection kicker. The RF Cogging system controls the gap position by changing only the radial position of the beam thus limiting the beam aperture and creating beam loss due to beam scraping. The Magnetic Cogging system controls the gap position with the magnetic field of the dipole correctors while the radial position feedback keeps the beam on a central orbit. Also with Magnetic Cogging the gap creation can occur earlier in the Booster cycle when the removed particles are at a lower energy. Thus Magnetic Cogging reduces the deposited energy of the lost particles (beam energy loss) and results in less beam loss activation. Energy loss was reduced by 40% by moving the gap creation energy from 700 MeV to 400 MeV when the Booster Cogging system was switched from RF Cogging to Magnetic Cogging in March 2015.

  19. Monlithic nonplanar ring oscillator and method

    NASA Technical Reports Server (NTRS)

    Nilsson, Alan C. (Inventor); Byer, Robert L. (Inventor)

    1991-01-01

    A monolithic nonplanar ring oscillator having an optically isotropic solid-state laser body for propagating laser radiation about a nonplanar ring path internal to the laser body is disclosed. The monolithic laser body is configured to produce a 2N reflection nonplanar ring light path, where N is an integer greater than or equal to 2, comprising 2N-1 total internal reflections and one reflection at a coupler in a single round trip. Undirectional traveling wave oscillation of the laser is induced by the geometry of the nonplanar ring path together with the effect of an applied magnetic field and partial polarizer characteristics of the oblique reflection from the coupler. The 6-reflection nonplanar ring oscillator makes possible otpimal unidirectional oscillation (low loss for the oscillating direction of propagation and, simultaneously high loss for the nonoscillating direction of propagation) in monolithic NPROs using materials with index of refraction smaller than the square root of 3, for example, laser glass.

  20. Reflex ring laser amplifier system

    DOEpatents

    Summers, M.A.

    1983-08-31

    The invention is a method and apparatus for providing a reflex ring laser system for amplifying an input laser pulse. The invention is particularly useful in laser fusion experiments where efficient production of high-energy and high power laser pulses is required. The invention comprises a large aperture laser amplifier in an unstable ring resonator which includes a combination spatial filter and beam expander having a magnification greater than unity. An input pulse is injected into the resonator, e.g., through an aperture in an input mirror. The injected pulse passes through the amplifier and spatial filter/expander components on each pass around the ring. The unstable resonator is designed to permit only a predetermined number of passes before the amplified pulse exits the resonator. On the first pass through the amplifier, the beam fills only a small central region of the gain medium. On each successive pass, the beam has been expanded to fill the next concentric non-overlapping region of the gain medium.

  1. Using cone beam computed tomography to detect the relationship between the periodontal bone loss and mucosal thickening of the maxillary sinus

    PubMed Central

    Sheikhi, Mahnaz; Pozve, Nasim Jafari; Khorrami, Ladan

    2014-01-01

    Background: Maxillary sinuses are covered by a 1 mm thick mucous membrane that when this membrane becomes inflamed, the thickness may increase 10-15 times. The common causes of odontogenic sinusitis are dental abscesses and periodontal disease. Computed tomography (CT) is considered the gold standard for sinus diagnosis. Recently, cone beam computed tomography (CBCT) has been introduced for dental and maxillofacial imaging, which has several advantages over traditional CT, including lower radiation dose and chairside process. This study aims to find the association between mucosal thickening (MT) of the sinus and periodontal bone loss (PBL) and pulpoperiapical condition. Materials and Methods: A total of 180 CBCT images were reviewed. PBL was assessed in six points under each sinus at the mesial and distal sides of the upper second premolar and first and second molars by measuring the distance from the alveolar crest to the point 2 mm under the cemento-enamel junction (CEJ). The MT was assessed at six points in the floor of the sinus precisely over the mentioned points. To assess the possible role of pulpoperiapical condition on the sinus MT, the existing teeth were classified into five groups due to the probable effect of each condition on the pulp and peri-apex. The statistical association between MT of sinus and PBL and pulpoperiapical condition was assessed using SPSS software (SPSS Inc., version 16.0, Chicago, IL, USA) and bivariate correlation and binary linear regression statistical tests (P < 0.05). Results: MT was observed in 39.4% of patients (mean = 4.68 ± 5.25 mm). PBL was seen in 33% of the patients (mean = 1.87 ± 1.63 mm). Linear regression test showed that there is an association between both PBL and pulpoperiapical condition and MT, but the effect of PBL was about 4 times stronger. Conclusion: This study showed that MT of the maxillary sinus was common among patients with PBL and MT of the maxillary sinus was significantly associated with PBL

  2. Effects and Correction of Closed Orbit Magnet Errors in the SNS Ring

    SciTech Connect

    Bunch, S.C.; Holmes, J.

    2004-01-01

    We consider the effect and correction of three types of orbit errors in SNS: quadrupole displacement errors, dipole displacement errors, and dipole field errors. Using the ORBIT beam dynamics code, we focus on orbit deflection of a standard pencil beam and on beam losses in a high intensity injection simulation. We study the correction of these orbit errors using the proposed system of 88 (44 horizontal and 44 vertical) ring beam position monitors (BPMs) and 52 (24 horizontal and 28 vertical) dipole corrector magnets. Correction is carried out numerically by adjusting the kick strengths of the dipole corrector magnets to minimize the sum of the squares of the BPM signals for the pencil beam. In addition to using the exact BPM signals as input to the correction algorithm, we also consider the effect of random BPM signal errors. For all three types of error and for perturbations of individual magnets, the correction algorithm always chooses the three-bump method to localize the orbit displacement to the region between the magnet and its adjacent correctors. The values of the BPM signals resulting from specified settings of the dipole corrector kick strengths can be used to set up the orbit response matrix, which can then be applied to the correction in the limit that the signals from the separate errors add linearly. When high intensity calculations are carried out to study beam losses, it is seen that the SNS orbit correction system, even with BPM uncertainties, is sufficient to correct losses to less than 10-4 in nearly all cases, even those for which uncorrected losses constitute a large portion of the beam.

  3. Asymmetric dipolar ring

    DOEpatents

    Prosandeev, Sergey A.; Ponomareva, Inna V.; Kornev, Igor A.; Bellaiche, Laurent M.

    2010-11-16

    A device having a dipolar ring surrounding an interior region that is disposed asymmetrically on the ring. The dipolar ring generates a toroidal moment switchable between at least two stable states by a homogeneous field applied to the dipolar ring in the plane of the ring. The ring may be made of ferroelectric or magnetic material. In the former case, the homogeneous field is an electric field and in the latter case, the homogeneous field is a magnetic field.

  4. Ring-imaging Cerenkov studies. Final performance report

    SciTech Connect

    Lopez, A.M.

    1997-03-13

    This project involved collaboration in the design, construction and testing of a prototype chamber capable of detecting Cerenkov rings. The chamber incorporated several novel techniques in that it used parallel-plate pad readout and a Cesium-iodide (CsI) solid photocathode. The pad system used gas multiplication where the gas was kept at low pressure to minimize photon losses due to absorption and back-scattering and to minimize ion collection times. Low pressure also lowers the chamber response to charged particles. The chamber gas was ethane at 20 torr and the chamber was operated at room temperature. The chamber was built at the University of Pennsylvania by a University of Puerto Rico graduate student, Jorge Millan. Initial tests at Pennsylvania using a hydrogen-discharge lamp indicated a quantum efficiency of 13% at 190 nm. The chamber was then tested in the M-Test beam line at Fermilab and behind the C3 beamline dump at Brookhaven Lab. Cerenkov rings were clearly observed with each photoelectron typically exciting one pad. On average each ring had five struck pads and only 10% of the events had hits in the center due to the charged particle. These results indicate that a RICH detector using a solid CsI photocathode coupled to a low-pressure, parallel-plate pad chamber is an excellent device for particle identification in high-rate environments when there is a need to cover large areas with minimum expense.

  5. Beam-beam effects in the Tevatron

    SciTech Connect

    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. APS storage ring vacuum system performance

    SciTech Connect

    Noonan, J.R.; Gagliano, J.; Goeppner, G.A.

    1997-06-01

    The Advanced Photon Source (APS) storage ring was designed to operated with 7-GeV, 100-mA positron beam with lifetimes > 20 hours. The lifetime is limited by residual gas scattering and Touschek scattering at this time. Photon-stimulated desorption and microwave power in the rf cavities are the main gas loads. Comparison of actual system gas loads and design calculations will be given. In addition, several special features of the storage ring vacuum system will be presented.

  7. COSY - a cooler synchrotron and storage ring

    SciTech Connect

    Martin, S.A.; Berg, G.P.A.; Hacker, U.; Hardt, A.; Kohler, M.; Osterfeld, F.; Prasuhn, D.; Riepe, G.; Rogge, M.; Schult, O.W.B.

    1985-10-01

    The storage ring COSY with phase space cooling and RF acceleration is designed to accept protons and light ions injected from the existing cyclotron JULIC or protons from the LINAC of the proposed neutron spallation source (SNQ). The lay-out of COSY was developed in cooperation with the Universities in Nordrhein-Westfalen and meets the experimental requirements of variable and high quality beams which are necessary for future nuclear research under discussion. The three essential properties of the storage ring will be: high luminosities and very efficient use of the beam in the storage ring by thin internal targets; energy variability in the range of 20 MeV to 1.5 GeV by RF acceleration; and very high beam quality through phase space cooling.

  8. CHALLENGES FOR THE SNS RING ENERGY UPGRADE

    SciTech Connect

    Plum, Michael A; Gorlov, Timofey V; Holmes, Jeffrey A; Hunter, W Ted; Roseberry, Jr., R Tom; Wang, Jian-Guang

    2012-01-01

    The Oak Ridge Spallation Neutron Source accumulator ring presently operates at a beam power of about 1 MW with a beam energy of about 910 MeV. A power upgrade is planned to increase the beam energy to 1.3 GeV. For the accumulator ring this mostly involves modifications to the injection and extraction sections. A variety of modifications to the existing injection section were necessary to achieve 1 MW, and the tools developed and the lessons learned from this work are now being applied to the design of the new injection section. This paper will discuss the tools and the lessons learned, and also present the design and status of the upgrades to the accumulator ring.

  9. Saturn's Spectacular Ring System

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Saturn's beautiful rings have fascinated astronomers since they were first observed by Galileo in 1610. The main rings consist of solid particles mostly in the 1 cm - 10 m range, composed primarily of water ice. The ring disk is exceptionally thin - the typical local thickness of the bright rings is tens of meters, whereas the diameter of the main rings is 250,000 km! The main rings exhibit substantial radial variations "ringlets", many of which are actively maintained via gravitational perturbations from Saturn's moons. Exterior to the main rings lie tenuous dust rings, which have little mass but occupy a very large volume of space. This seminar will emphasize the physics of ring-moon interactions, recent advances in our understanding of various aspects of the rings obtained from observations taken during 1995 when the rings appeared edge-on to the Earth and then to the Sun, and observations in subsequent years from HST.

  10. Terahertz quantum cascade laser coupled with high efficiency to the low loss optical modes of cylindrical hollow-core waveguides

    NASA Astrophysics Data System (ADS)

    Vitiello, Miriam S.; Xu, J. H.; Beltram, F.; Tredicucci, A.; Mitrofanov, O.; Harrington, James A.; Beere, H. E.; Ritchie, D. A.

    2011-10-01

    We demonstrate that azimuthally polarized micro-ring THz quantum-cascade lasers can be coupled to hollow metallic waveguides with efficiencies >=96% and perfectly matched with the TE01 waveguide mode, giving attenuation losses < 3dB/m. The use of Ag coated-flexible pipe waveguides allows propagation of either vertically polarized or azimuthally polarized QCL beams with propagation losses as low as 2.1-4.4 dB/m and bending losses lower than 1.2 dB.

  11. Current state of ring imaging Cherenkov detectors

    SciTech Connect

    Coutrakon, G.B.

    1984-02-01

    This paper reviews several ring imaging Cherenkov detectors which are being used or developed to identify particles in high energy physics experiments. These detectors must have good detection efficiency for single photon-electrons and good spatial resolution over a large area. Emphasis is placed on the efficiencies and resolutions of these detectors as determined from ring imaging beam tests and other experiments. Following a brief review of the ring imaging technique, comparative evaluations are made of different forms of detectors and their respective materials.

  12. Bunch coalescing in the Fermilab Main Ring

    SciTech Connect

    Wildman, D.; Martin, P.; Meisner, K.; Miller, H.W.

    1987-03-01

    A new rf system has been installed in the Fermilab Main Ring to coalesce up to 13 individual bunches of protons or antiprotons into a single high-intensity bunch. The coalescing process consists of adiabatically reducing the h = 1113 Main Ring rf voltage from 1 MV to less than 1 kV, capturing the debunched beam in a linearized h = 53 and h = 106 bucket, rotating for a quarter of a synchrotron oscillation period, and then recapturing the beam in a single h = 1113 bucket. The new system will be described and the results of recent coalescing experiments will be compared with computer-generated particle tracking simulations.

  13. Ring current proton decay by charge exchange

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Hoffman, R. A.; Fritz, T.

    1975-01-01

    Explorer 45 measurements during the recovery phase of a moderate magnetic storm have confirmed that the charge exchange decay mechanism can account for the decay of the storm-time proton ring current. Data from the moderate magnetic storm of 24 February 1972 was selected for study since a symmetrical ring current had developed and effects due to asymmetric ring current losses could be eliminated. It was found that after the initial rapid decay of the proton flux, the equatorially mirroring protons in the energy range 5 to 30 keV decayed throughout the L-value range of 3.5 to 5.0 at the charge exchange decay rate calculated by Liemohn. After several days of decay, the proton fluxes reached a lower limit where an apparent equilibrium was maintained, between weak particle source mechanisms and the loss mechanisms, until fresh protons were injected into the ring current region during substorms. While other proton loss mechanisms may also be operating, the results indicate that charge exchange can entirely account for the storm-time proton ring current decay, and that this mechanism must be considered in all studies involving the loss of proton ring current particles.

  14. Stirling engine piston ring

    DOEpatents

    Howarth, Roy B.

    1983-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  15. A micrometeorite erosion model and the age of Saturn's rings

    NASA Technical Reports Server (NTRS)

    Northrop, T. G.; Connerney, J. E. P.

    1987-01-01

    An erosional model of Saturn's rings is proposed based on theoretical studies of the high charge-to-mass ratio particles in Saturn's ring plane, and assuming that the B and C rings were initially formed as one ring with the optical thickness of the present B ring. The erosion rate is calculated using data from observed micrometeorite fluxes, and a ring age of 4.4-76 Myr is determined which is inconsistent with the 4.5-Gyr ring lifetime required by the cosmogonic ring hypothesis. The sharpness of the transition between the B and C rings suggests that the principal mass loss is through particles moving at a few m/sec with respect to the parent bodies from which they were eroded.

  16. Hearing Loss

    MedlinePlus

    ... version of this page please turn Javascript on. Hearing Loss What is Hearing Loss? Hearing loss is a common problem caused by ... sec Click to watch this video Types of Hearing Loss Hearing loss comes in many forms. It can ...

  17. Actin Rings of Power.

    PubMed

    Schwayer, Cornelia; Sikora, Mateusz; Slováková, Jana; Kardos, Roland; Heisenberg, Carl-Philipp

    2016-06-20

    Circular or ring-like actin structures play important roles in various developmental and physiological processes. Commonly, these rings are composed of actin filaments and myosin motors (actomyosin) that, upon activation, trigger ring constriction. Actomyosin ring constriction, in turn, has been implicated in key cellular processes ranging from cytokinesis to wound closure. Non-constricting actin ring-like structures also form at cell-cell contacts, where they exert a stabilizing function. Here, we review recent studies on the formation and function of actin ring-like structures in various morphogenetic processes, shedding light on how those different rings have been adapted to fulfill their specific roles. PMID:27326928

  18. New Dust Belts of Uranus: One Ring, Two Ring, Red Ring, Blue Ring

    SciTech Connect

    de Pater, I; Hammel, H B; Gibbard, S G; Showalter, M R

    2006-02-02

    We compare near-infrared observations of the recently discovered outer rings of Uranus with HST results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced via impacts into the embedded moon Mab, which apparently orbits at a location where non-gravitational perturbations favor the survival and spreading of sub-micron sized dust. R/2003 U 2 more closely resembles Saturn's G ring.

  19. Numerical Simulation of Beam-Beam Effects in the Proposed Electron-Ion Colider at Jefferson Lab

    SciTech Connect

    Balsa Terzic, Yuhong Zhang

    2010-05-01

    One key limiting factor to a collider luminosity is beam-beam interactions which usually can cause serious emittance growth of colliding beams and fast reduction of luminosity. Such nonlinear collective beam effect can be a very serious design challenge when the machine parameters are pushed into a new regime. In this paper, we present simulation studies of the beam-beam effect for a medium energy ring-ring electron-ion collider based on CEBAF.

  20. Commissioning and Early Operation Experience of the NSLS-II Storage Ring RF System

    SciTech Connect

    Gao, F.; Rose, J.; Cupolo, J.; Dilgen, T.; Rose, B.; Gash, W.; Ravindranath, V.; Yeddulla, M.; Papu, J.; Davila, P.; Holub, B.; Tagger, J.; Sikora, R.; Ramirez, G.; Kulpin, J.

    2015-05-03

    The National Synchrotron Light Source II (NSLS-II) is a 3 GeV electron X-ray user facility commissioned in 2014. The storage ring RF system, essential for replenishing energy loss per turn of the electrons, consists of digital low level RF controllers, 310 kW CW klystron transmitters, CESR-B type superconducting cavities, as well as a supporting cryogenic system. Here we will report on RF commissioning and early operation experience of the system for beam current up to 200mA.