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MOZBC01 | National Nuclear Security and Other Applications of Rare Isotopes | target, site, factory, simulation | 124 | |||||
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The proposed Rare Isotope Accelerator will produce large quantities of short-lived isotopes in beams suitable for experiments in low energy nuclear physics and nuclear astrophysics. The full suite of particles available offers the opportunity for advances in other scientific fields and applied technologies, including national security, medical technology, material science, and nuclear energy.
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MOPAS098 | Dynamic Collaborative Documentation at the Brookhaven National Laboratory Collider-Acclerator Department | controls, site, diagnostics | 658 | |||||
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Funding: The work was performed under the US Department of Energy Contract No. DE-AC02-98CH1-886, and with support of RIKEN(Japan) and Renaissance Technologies Corp.(USA) |
Centralization of information pertaining to accelerators can benefit accelerator operation and development. Further, retention and the changeable nature of information present challenges to accelerator operation, particularly in instances of turnover. MediaWiki is free, server-based software licensed under the GNU General Public License that uses PHP to render data stored in a MySQL database as interactive web documents, and is designed to produce collaborative documentation. The MediaWiki engine was implemented at BNL, and this paper describes the first year of use by the Operations, Controls, and RF groups at the Collider-Accelerator Department, including code modifications, common practices, and the use of the wiki as a training tool. |
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TUXKI03 | Neutrino and Other Beam-Lines at J-PARC | target, proton, hadron, kaon | 686 | |||||
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The T2K project, the next-generation long base-line neutrino oscillation experiment to explore neutrino mass and mixing (further CPV), is one of the main motivations to construct J-PARC, The Japan Proton Accelerator Research Complex at Tokai. It will employ the 50 GeV proton synchrotron to produce neutrino super-beam, and a 50 kt water Cherenkov neutrino detector at Kamioka mine, Super-Kamiokande, as a far neutrino detector. The baseline length of 295 km. The neutrino beam-line is in the midst of its apparatus production and civil construction, towards the beam commissionning scheduled in April 2009. One of the main features of the beam-line is that the axis of the beam optics is displaced by a few degrees from the far detector direction to produce a narrower and lower neutrino energy spectrum than that of conventional on-axis beam. Our beam-line design makes it possible to adjust the off-axis angle, i.e. neutrino beam energy, to maximize neutrino oscillation effect. In this talk I will also briefly introduce other econdary beam-lines at J-PARC, the hadron beam lines and neutron and muon beam lines.
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TUXAB01 | Absolute Measurement of Electron Cloud Density | electron, ion, quadrupole, simulation | 754 | |||||
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Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U. S. Department of Energy, LLNL and LBNL, under contracts No. W-7405-Eng-48 and DE-AC02-05CH11231. |
Beam interaction with background gas and walls produces ubiquitous clouds of stray electrons that frequently limit the performance of particle accelerator and storage rings. Counterintuitively we obtained the electron cloud accumulation by measuring the expelled ions that are originated from the beam-background gas interaction, rather than by measuring electrons that reach the walls. The kinetic ion energy measured with a retarding field analyzer (RFA) maps the depressed beam space-charge potential and provides the dynamic electron cloud density. Clearing electrode current measurements give the static electron cloud background that complements and corroborates with the RFA measurements, providing an absolute measurement of electron cloud density during a 5 us duration beam pulse in a drift region of the magnetic transport section of the High-Current Experiment (HCX) at LBNL.*
* M. Kireeff Covo, A. W. Molvik, A. Friedman, J.-L. Vay, P. A. Seidl, G. Logan, D. Baca, and J. L. Vujic, Phys. Rev. Lett. 97, 054801 (2006). |
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TUPMN016 | Upgrade of the BESSY Femtoslicing Source | laser, photon, undulator, electron | 950 | |||||
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The BESSY femtoslicing source as the first undulator-based source has succesfully demonstrated its capabilities of providing ~100 fs x-ray pulses in an energy range from 300 to 1400 eV with linear and circular polarisation. With this type of slicing source exhibiting an excellent signal-to-noise ratio, the number of detected photons at the user frontend is still limited to ~103 / sec. Several improvements are underway to increase the photon flux and to improve the stability of the source. An upgrade of the present laser system will increase the pulse repetition rate from 1 to 3 kHz. Furthermore, a new evacuated laser beam path will be implemented to provide higher pointing stability and an automated postion feedback. The benefits and limitations of these improvements will be discussed, and new measurements will be presented.
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TUPMS024 | Development of a 100 mm Period Hybrid Wiggler for the Australian Synchrotron Project | wiggler, multipole, electron, synchrotron | 1233 | |||||
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Funding: Australian Synchrotron Project |
This paper summarizes the final magnetic measurement for a hybrid wiggler installed at the Australian Synchrotron Project (ASP). This device uses an anti-symmetric, hybrid design with a period of 100 mm and 40 full-strength Vanadium-Permendur poles surrounded by Neodynium-Iron-Boron magnets. It is designed to operate at two gaps with critical energies of 11.4 (14mm) and 9.6 keV (18.16mm) and to have a maximum gap with the field strength By ≤ 50 G. The wiggler's drive mechanism is capable of moving from minimum to maximum gap in 96 seconds. End terminations are designed to maintain the electron trajectory on-axis. The straightness of the electron orbit is controlled by moving the poles vertically and horizontally. The integrated multipoles are controlled over the interval |x| < 25 mm and all gap sizes by moving the side magnets, installing correction magnets at the wiggler entrance and exit and using correction coils. All adjustments have been made using threaded fasteners. No shims have been used. |
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TUPAN007 | 3-D Magnetic Calculation Methods for Spiral Scaling FFAG Magnet Design | magnet-design, lattice, acceleration, extraction | 1401 | |||||
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Funding: ANR (French Research Agency) |
2-D and 3-D magnetic calculation tools and methods have been developed at SIGMAPHI, in collaboration with IN2P3/LPSC, to design spiral FFAG magnets. These tools are currently being used for RACCAM spiral scaling FFAG magnet design. In the particular case of a spiral gap shaped magnet, a careful magnetic design has to be realized in order to keep both vertical and horizontal tunes constant during acceleration process. Promising results, obtained from tracking in 3-D field maps, demonstrate the efficiency of the horizontal and vertical tune adjustment methods presented in this paper. |
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TUPAN027 | A New Complementary-Scan Technique for Precise Measurements of Resonance Parameters in Antiproton-Proton Annihilations | resonance, antiproton, luminosity, pick-up | 1448 | |||||
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A new technique for precision measurements of resonance widths in antiproton-proton annihilations is presented. It is based on the analysis of excitation curves obtained by scanning the resonance twice, at constant orbit and at constant magnetic bend field, in an antiproton storage ring. The technique relies on precise revolution-frequency and orbit-length measurements, while making the results almost independent of the machine's phase-slip factor. The uncertainty is dominated by event statistics. The technique was recently applied by Fermilab Experiment E835 at the Antiproton Accumulator to obtain the most precise measurements to date of the total and partial widths of the psi(2S) charmonium meson. Future applications may include the PANDA experiment at the FAIR facility in Darmstadt.
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On behalf of the Fermilab E835 Collaboration |
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TUPAN031 | Touschek Background and Beam Lifetime Studies for the DAFNE Upgrade | simulation, optics, scattering, insertion | 1454 | |||||
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For the low energy collider DAFNE the machine induced backgrounds into the experiments as well as the beam lifetime are dominated by the Touschek effect. Many efforts have been put in its reduction: by adjusting optical parameters, by inserting additional collimators, as well as by simulating and tracking scattered particles in order to find the proper actions that allow reducing these effects. Studies on the distribution and trajectories of the Touschek particles along the ring are discussed here for the Siddarta run configuration with the crabbed waist scheme, together with an evaluation of the beam lifetime. Effectiveness of the scrapers installed in the two rings has been investigated with the new machine configuration and new optimized positions along the beam pipe have been found.
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TUPAN102 | Numerical Study of the Very Forward Background from the Proton-Proton Collisions in the Experimental Insertions of the LHC | simulation, hadron, insertion, luminosity | 1619 | |||||
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The results from the numerical DPMJET-FLUKA simulation of the background in the experimental IR's of the LHC are presented. DPMJET3 is used for the generation and analysis of the products from the p-p collision leaving the interaction point in the very forward region. A multi-particle transport code FLUKA is used for the simulation of the resulting secondary cascades in the structure of the LHC long straight sections. The background formation is estimated and analyzed in the LSS's at the locations of the TAN absorber, Roman Pot stations and Beam Loss Monitors, for the purposes of the machine protection and planning of the operation of the detectors.
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TUPAS049 | 50 Tesla Superconducting Solenoid for Fast Muon Cooling Ring | collider, controls, target, simulation | 1757 | |||||
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Funding: DOE grant #DE-FG02-06ER41405 |
A conceptual design is presented for the 50 Tesla superconducting solenoids that are required for an optimized fast cooling ring in current designs for multi-TeV muon colliders. The solenoid utilizes high-performance multi-filament Bi-2212/Ag round strand. The conductor is a cable-in-conduit consisting of six such strands cabled around a thin-wall spring tube then drawn within an outer sheath. The spring tube and the sheath are made from high-strength superalloy Inconel. The solenoid coil comprises 5 concentric shells supported independently in the conventional manner. Each shell consists of a winding of the structured cable, impregnated in the voids between cables but empty inside so that the spring tubes decouple stress so that it cannot strain-degrade the fragile strands, and a high-modulus overband. An expansion bladder is located between the winding and the overband, and is pressurized and then frozen to provide hydraulic compressive preload to each shell. This approach makes it possible to accommodate ~10 T field contribution from each shell without degradation, and provides distributed refrigeration so that heat is removed throughout the windings. |
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TUPAS066 | Interaction Region Design for a Super-B Factory | radiation, interaction-region, factory, synchrotron | 1805 | |||||
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Funding: Work supported by US DOE contract DE-AC02-76SF00515 |
We present a preliminary design of an interaction region for a Super-B Factory with luminosity of 1x1036 cm2/s. The collision has a ± 17 mrad crossing angle and the first magnetic element starts 30 cm from the collision point. We show that synchrotron radiation backgrounds are controlled and are at least as good as the backgrounds calculated for the PEP-II accelerator. How the beams get into and out of a shared beam pipe is illustrated along with the control of relatively high synchrotron radiation power from the outgoing beams. The high luminosity makes radiative bhabha backgrounds significantly higher than that of the present B-Factories and this must be addresed in the initial design. |
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TUPAS068 | A Transverse Beam Instability in the PEP-II HER Induced by Discharges in the Vacuum System | vacuum, monitoring, coupling, betatron | 1811 | |||||
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Funding: Work supported by US Dept. of Energy |
During Run 5, PEP-II has been plagued by beam instabilities causing beam aborts due to radiation in the BaBar detector or due to fast beam loss triggering the dI/dt interlock. The latest of such instabilities occurred in the High Energy Ring (HER), severely curtailing the maximum beam current achievable during physics running. Techniques used in tracking down this instability included fast monitoring of background radiation, temperatures and vacuum pressure. In this way, the origin of the instability was localized and inspection of the vacuum system revealed several damaged bellows shields. Replacing these units significantly reduced the incident rate but did not eliminate it fully. After the end of the run, a number of damaged rf seals were found, possibly having caused the remaining incidents of instability. In this paper we will outline the steps taken to diagnose and remedy the issue and also compare the different signatures of vacuum-induced instabilities we have seen in both rings of PEP-II during the run. |
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TUPAS106 | Observation of Experimental Background in RHIC Polarized Proton Run 2006 | proton, vacuum, interaction-region, collimation | 1883 | |||||
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Funding: * Work supported by U. S. DOE under contract No DE-AC02-98CH1-886 |
There are three main sources of the experimental background at RHIC. The beam-gas induced background is associated with the vacuum pressure, the beam-chamber-interaction induced background can be improved by collimations, and the beam-beam induced background is somewhat inherent, and probably harmless for the experimental data taking. The zero degree calorimeter (ZDC) is an essential luminosity detector for heavy ion operations in RHIC. It is shown that, however, the ratio of ZDC singles (background) and coincident rate is also useful in proton runs for background evaluations. In this article, the experimental background problem in RHIC polarized proton runs is reported. |
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WEOBAB01 | Electromagnetic Background Tests for the ILC Interaction Point Feedback System | feedback, electron, luminosity, extraction | 1970 | |||||
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We present results obtained with the T-488 experiment at SLAC Endstation A (ESA). A material model of the ILC extraction-line design was assembled and installed in ESA. The module includes materials representing the mask, beamline calorimeter, and first extraction quadrupole, encompassing a stripline interaction-point feedback system beam position monitor (BPM). The SLAC high-energy electron beam was used to irradiate the module in order to mimic the electromagnetic (EM) backgrounds expected in the ILC interaction region. The impact upon the performance of the feedback BPM was measured, and compared with detailed simulations of its expected response.
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WEPMN007 | Introducing a Homepage for Information Retrieval and Backup of the Ground Vibration Measurements and Mechanical Vibrations of the Superconducting Modules at DESY | site, ground-motion, synchrotron, synchrotron-radiation | 2059 | |||||
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Funding: Work supported by the Commission of the European Communities under the 6th Framework Program Structuring the European Research Area, contract number RIDS-011899. |
In this paper, we will introduce our homepage (http://vibration.desy.de) which is used for the storage and dissemination of our ground motion measurement data of 20 sites around the world and the XFEL/ILC superconducting module data. This homepage is open to the scientific community and the data can be utilized for planning of future accelerator facilities and design of future prototypes of module vessels containing cold mass. |
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WEPMN090 | Recent RF Results from the MuCool Test Area | resonance, coupling, radiation, linac | 2239 | |||||
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Funding: Supported by the USDOE Office of High Energy Physics |
The MuCool Experiment has been continuing to take data with 805 and 201 MHz cavities in the MuCool Test Area. The system uses rf power sources from the Fermilab Linac. Although the experimental program is primarily aimed at the Muon Ionization Cooling Experiment (MICE), we have been studying the dependence of rf limits on frequency, cavity material, high magnetic fields, gas pressure, coatings, etc. with the general aim of understanding the basic mechanisms involved. The 201 MHz cavity, essentially a prototype for the MICE experiment, was made using cleaning techniques similar to those employed for superconducting cavities and operates at its design field with very little conditioning. |
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THOAC01 | ATF Extraction Line Laser-Wire System | laser, electron, extraction, photon | 2636 | |||||
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Funding: PPARC LC-ABD Collaboration Royal Society Daiwa Foundation Commission of European Communities under the 6th Framework Programme Structuring the European Research Area, contract number RIDS-011899 |
The ATF extraction line laser-wire (LW) aims to achieve a micron-scale laser spot size and to verify that micron-scale beam profile measurements can be performed at the International Linear Collider beam delivery system. Recent upgrades to the LW system are presented together with recent results including the first use of the LW as a beam diagnostic tool. |
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THPMN010 | GUINEA-PIG++ : An Upgraded Version of the Linear Collider Beam-Beam Interaction Simulation Code GUINEA-PIG | simulation, luminosity, linear-collider, collider | 2728 | |||||
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GUINEA-PIG++ is a newly developed object-oriented version of the Linear Collider beam-beam simulation program GUINEA-PIG. The main goals of this project are to provide a reliable, modular, documented and versatile framework enabling convenient implementation of new features and functionalities. Examples of improvements described in this paper are an easy interface to study the impact of electromagnetic effects on Bhabha event selections, a treatment of spin depolarization effects, automatic consistency checks and adjustments of internal computational parameters, upgraded input/output and user interface, an optimised setup for massive production on distributed computing GRIDs. A possible setup to perform fast parallelised computations is also discussed.
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THPMN079 | Simulation of ILC Feedback BPM Signals in an Intense Background Environment | feedback, simulation, extraction, alignment | 2889 | |||||
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Funding: This work is supported in part by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899. |
Experiment T-488 at SLAC, End Station A recorded distorted BPM voltage signals and an accurate simulation of these signals was performed. Geant simulations provided the energy and momentum spectrum of the incident spray and secondary emissions, and a method via image charges was used to convert particle momenta and number density into BPM stripline currents. Good agreement was achieved between simulated and measured signals. Further simulation of experiment T-488 with incident beam on axis and impinging on a thin radiator predicted minimal impact due to secondary emission. By extension to worst case conditions expected at the ILC, simulations showed that background hits on BPM striplines would have a negligible impact on the accuracy of beam position measurements and hence the operation of the FONT feedback system |
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THPMN080 | Incoherent pair background processes with full polarizations at the ILC | polarization, photon, luminosity, collider | 2892 | |||||
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Funding: This work is supported in part by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899. |
Incoherent background pair production processes are studied with respect to full polarizations of all states. Real initial photon polarizations are obtained via a QED calculation of the beamstrahlung process. Virtual photon polarizations are related to the electric field of the colliding bunches at the point of pair production. An explicit expression for the virtual photon polarization vector is developed and found to have no circular polarization component. Pair polarization states are highly dependent on initial state circular polarization and are consequently produced almost unpolarized. The Breit-Wheeler cross-section with full polarizations is calculated and coded into the CAIN pair generator program. Numerical evaluations of the ILC operating in the seven proposed collider parameter sets shows that there are 10-20% less low energy pairs than previously thought. Collider luminosity as calculated by CAIN remains the same. |
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THPMN100 | Suppression of Muon Backgrounds Generated in the ILC Beam Delivery System | positron, simulation, beam-losses, electron | 2945 | |||||
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Particle fluxes generated from the interactions of beam halo with the collimators in the ILC Beam Delivery System (BDS) can exceed tolerable levels for the collider detectors and create hostile radiation environment in the interaction region. Thorough analysis of the BDS model, beam loss patterns, driving geometry factors and physics processes along with verification of the simulation codes were performed for the current ILC BDS layout with 250-GeV electron and positron beams crossing at 14 mrad with a push-pull detector option. Muon flux reduction by distributed toroids (doughnut-type spoilers) in comparison with magnetic iron walls filling the BDS tunnel are calculated and analysed in great detail. Shielding conditions which allow occupancy of the interaction region while the full power beam is on the linac tuneup dump are also studied.
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THPMS059 | Correlating Pulses from Two Spitfire, 800nm Lasers | laser, acceleration, photon, electron | 3121 | |||||
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Funding: Department of Energy contracts DE-AC02-76SF00515, DE-FG03-97ER41043-III |
The E163 laser acceleration experiments conducted at SLAC have stringent requirements on the temporal properties of two regeneratively amplified, 800nm, Spitfire laser systems. To determine the magnitude and cause of timing instabilities between the two Ti:Sapphire amplifiers, we pass the two beams through a cross-correlator and focus the combined beam onto a Hamamatsu G1117 photodiode. The photodiode has a bandgap such that single photon processes are suppressed and only the second order, two-photon process produces an observable response. The response is proportional to the square of the intensity. The diode is also useful as a diagnostic to determine the optimal configuration of the compression cavity.
Yoshihiro Takagi et al, 'Multiple- and Single-shot autocorrelator based on two-photon conductivity in semiconductors.' Optics Letters, Vol. 17, No. 9, May 1, 1992. |
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THPMS086 | Plasma Lens for US Based Super Neutrino Beam at Either FNAL or BNL | plasma, target, focusing, simulation | 3184 | |||||
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Funding: Work supported under Contract No. DE-AC02-98CH1-886 with the US Department of Energy |
Plasma lens concept is examined as an alternative to focusing horns and solenoids for a neutrino beam facility. The concept is based on a combined high-current lens/target configuration. Current is fed at an electrode located downstream from the beginning of the target where pion capturing is needed. Some of the current flows through the target, while the rest is carried by plasma outside the target. A second plasma lens section, with an additional current feed, follows the target. Plasma of this section is immersed in a solenoidal magnetic field to facilitate its current profile shaping to optimize pion capture. Simulation of the second section alone yielded a 10% higher neutrino production than the horn system. Plasma lenses have additional advantages: larger axial currents, high signal purity: minimal neutrino background in anti-neutrino runs. Lens medium consists of plasma, consequently, particle absorption and scattering is negligible. Withstanding high mechanical and thermal stresses is not an issue. Results of capturing and focusing obtained for various plasma lens configurations will be presented. |
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THPMS091 | The Superconducting Magnets of the ILC Beam Delivery System | octupole, superconducting-magnet, extraction, dipole | 3196 | |||||
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Funding: Work supported by the US Department of Energy under contract DE-AC02-98CH10886. |
A wide variety of superconducting magnets are needed in the ILC Beam Delivery System (BDS) to maximize luminosity and minimize experimental backgrounds. Compact final focus quadrupoles and multifunction correction coils are used with 14 mr total crossing angle to focus incoming beams to few nanometer spot sizes while focusing outgoing disrupted beams into a separate extraction beam line. Large aperture anti-solenoids correct deleterious nonlinear effects that arise due to the overlap of focusing fields with the main detector solenoid. Far from the interaction point (IP) sets of strong small aperture octupoles help minimize backgrounds at the IP due to beam halo particles while weak large aperture dipoles integrated with the experimental detector reduce backgrounds due to beamstrahlung pairs generated at the IP. The physics requirements and magnetic design solutions for these magnets are reviewed in this paper. |
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THPAN020 | A Dispersionless Algorithm for Calculating Wake Potentials in 3D | linac, simulation | 3268 | |||||
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Funding: This work is supported in part by the EU under contract number RIDS-011899 (EUROTeV). |
Accurate computations of wake potentials are an important task in modern accelerator design. Short bunches used in high energy particle accelerators excite very high-frequency fields. The geometrical size of accelerating structures exceeds the wavelength of the excited fields by many orders of magnitude. The application of codes such as TBCI, MAFIA or tamBCI are limited due to numerical dispersion effects and memory needs. Recently new codes like PBCI have been developed to overcome these problems. In this work the utilization of dispersionless directions in the leap-frog update scheme on a Cartesian grid are proposed for accurate simulations. In conjunction with a conformal modelling technique which allows for the full Courant time step a moving window technique can be applied. This was previously implemented in a 2D code. In this publication an extension to arbitrary three dimensional problems are presented. |
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THPAN085 | Two-Stream Instability Analysis For Propagating Charged Particle Beams With a Velocity Tilt | plasma, simulation, ion, emittance | 3417 | |||||
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Funding: This research was supported by the U. S. DOE through Lawrence Berkeley National Laboratory, Princeton Plasma Physics Laboratory for the Heavy Ion Fusion Science-Virtual National Laboratory. |
The linear growth of the two-stream instability for a charged particle beam that is longitudinally compressing as it propagates through a background plasma (due to an applied velocity tilt) is examined. Detailed, 1D particle-in-cell simulations are carried out to examine the growth of a wave packet produced by a small amplitude density perturbation in the background plasma. Recent analytic and numerical work by Startsev and Davidson [1] predicted reduced linear growth rates, which are indeed observed in the simulations. Here, small-signal asymptotic gain factors are determined in a semi-analytic analysis and compared with the simulation results in the appropriate limits. Nonlinear effects in the PIC simulations, including wave breaking and particle-trapping, are found to limit the linear growth phase of the instability for both compressing and non-compressing beams.
[1] Phys. Plasmas 13, 62108 (2006) |
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THPAS014 | MICE: the International Muon Ionization Cooling Experiment: Phase Space Cooling Measurement | emittance, factory, simulation, electron | 3543 | |||||
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Muon storage rings have been proposed for use as sources of intense high-energy neutrino beams and as the basis for multi-TeV lepton-antilepton colliding-beam facilities. Optimizing the performance of such facilities is likely to require the phase-space compression (cooling) of the muon beam prior to acceleration and storage. The short muon lifetime makes traditional beam-cooling techniques ineffective. Ionization cooling, a process in which the muon beam is passed through a series of energy absorbers followed by accelerating RF cavities, is thus the technique of choice. The international Muon Ionization Cooling Experiment (MICE) collaboration is constructing the apparatus for a muon ionization-cooling demonstration experiment, to be conducted at Rutherford Appleton Laboratory over the next 3 years. The MICE cooling channel, its instrumentation, and its implementation at the Rutherford Appleton Laboratory are described together with the predicted performance of the channel and the measurements that will be made.
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THPAS057 | Significant Lifetime and Background Improvements in PEP-II by Reducing the 3rd Order Chromaticity in LER with Orbit Bumps | sextupole, coupling, lattice, luminosity | 3618 | |||||
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Funding: *Work supported by Department of Energy contract DE-AC03-76SF00515. |
Orbit bumps in sextupoles are routinely used for tuning the luminosity in the PEP-II B-Factory. Anti-symmetric bumps in a sextupole pair generate dispersion, while symmetric bumps induce a tune shift and beta beat. By coming two of these symmetric bumps with opposite signs where the second pair is 90 degree away, the tune shift cancels and the beta beat doubles. In the low energy ring (LER) we have four sextupole pairs per arc, where pair 1 and 3 are at the same betatron phase and pair 2 and 4are 90 degree away. By making two symmetric bumps with opposite sign in pair 1 and 3 the tune shift and the beta beat outside this region cancel, BUT the LER lifetime improved by a factor of three, losses by a factor of five, and the beam-beam background in the drift chamber of the BaBar detector by 20%. Simulations showed that the phase change at the second sextupole pair introduced by the beta beat can completely cancel the third order chromaticity. |
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THPAS083 | Charge and Current Neutralization of an Ion Beam Pulse by Background Plasma in Presence of Applied Magnetic Field and Gas Ionization | plasma, ion, simulation, focusing | 3675 | |||||
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Funding: *Research supported by the U. S. Department of Energy under the auspices of the Heavy Ion Fusion Science Virtual National Laboratory. |
Background plasma can be used as a convenient tool for manipulating intense charge particle beams, for example, for ballistic focusing and steering, because the plasma can effectively reduce the space-charge potential and self-magnetic field of the beam pulse. We previously developed a reduced analytical model of beam charge and current neutralization for an ion beam pulse propagating in a cold background plasma. The reduced-fluid description provides an important benchmark for numerical codes and yields useful scaling relations for different beam and plasma parameters. This model has been extended to include the additional effects of a solenoidal magnetic field and gas ionization. Analytical studies show that a sufficiently large solenoidal magnetic field can increase the degree of current neutralization of the ion beam pulse. The linear system of equations has been solved analytically in Fourier space. For a strong enough applied magnetic field, poles emerge in Fourier space. These poles are an indication that whistler waves and lower hybrid waves are excited by the beam pulse. |
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FRZKI02 | Neutrino Physics | proton, target, booster, controls | 3835 | |||||
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Twenty years have passed after the supernova SN1987A. Before SN1987A, it was often said that neutrino physics was largely an art of learning a great deal by observing nothing. But after SN1987A, the neutrino became a little less mysterious. The solar neutrino deficit which was observed in the Homestake solar neutrino experiment, was confirmed by Kamiokande, Gallex and SAGE. An atmospheric neutrino anomaly was observed in Kamiokande. IMB, MACRO and SUDEN reconfirmed this anpmaly. In 1998 Super-Kamiokande obtained the evidence of atmospheric neutrino oscillations. This was the first discovery of a finite neutrino mass. The atmospheric neutrino oscillations were reconfirmed by K2K. In 2002 SNO detected the evidence of flavor-transformation of solar neutrinos, and KamLAND detected the evidence of reactor antineutrino oscillations. In my talk what we learned from the above neutrino experiments is briefly reviewed, and what we will learn by on-going and proposed neutrino experiments is discussed.
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FRPMN027 | Non-Intercepting Electron Beam Transverse Diagnostics with Optical Diffraction Radiation at the DESY FLASH Facility | radiation, electron, target, diagnostics | 3982 | |||||
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Funding: Work supported by the European Comunity Infra-structure Activity under the FP6 Structuring the European Research Area program (CARE, contract number RII3-CT-2003-506395) |
The characterization of the transverse phase space for high charge density and high energy electron beams is a fundamental requirement in many particle accelerator facilities, since knowledge of the characteristics of the accelerated beams is of great importance for the successful development of the next generation light sources and linear colliders. The development of suitable beam diagnostics, non-invasive and non-intercepting, is therefore necessary to measure the properties of such beams. Optical Diffraction Radiation (ODR) is considered the most promise candidate, as testified by the interest of many laboratories all around the world. An experiment based on the detection of ODR has been set up at DESY FLASH Facility to measure the electron beam transverse parameters. The radiation is emitted by a 700 MeV-energy electron beam passing through a slit of 0.5 mm or 1 mm aperture depending on the beam size. The slit is opened by chemical etching on a screen made of aluminum deposited on a silicon substrate. Radiation is then detected by a air-cooled high sensitivity CCD camera. The status of the experiment and preliminary results are reported. |
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FRPMN045 | Beam Position Monitor and its Calibration in J-PARC LINAC | linac, monitoring, quadrupole, pick-up | 4072 | |||||
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The beam commissioning of J-PARC linac has been started in November 2006. Beam Position Monitors (BPMs) which have been calibrated on the bench setup with a scanning wire, utilize beam based calibration to relate the BPM center and the center of Q magnet. In this presentation, detail of installed BPM and the calibration methods are described.
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FRPMN107 | Observations of Rising Tune During the Injection Instability of the IPNS RCS Proton Bunch | electron, injection, proton, space-charge | 4345 | |||||
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Funding: This work is supported by the U. S. DOE under contract no. W-31-109-ENG-38. |
In the IPNS RCS, a single proton bunch (h=1) is accelerated from 50 MeV to 450 MeV in 14.2 ms. The bunch experiences an instability shortly after injection (<1 ms). During the first 1 ms, the beam is bunched but little acceleration takes place; thus, this period of operation is similar to that of a storage ring. Natural vertical oscillations (assumed to be tune lines) show the vertical tune to be rising toward the bare tune value, suggesting neutralization of space charge and a reduction of its detuning effects. Neutralization time near injection ranges from 0.25 ms - 0.5 ms, depending on the background gas pressure. Oscillations move from the LSB to the USB before disappearing. Measurements made with a recently installed pinger system show the horizontal chromaticity to be positive early but approaching zero later in the cycle. The vertical chromaticity is negative throughout the cycle. During pinger studies, two lines are observed, suggesting the formation of islands. Neutralization of the beam space charge implies the generation of plasma in the beam volume early in the cycle which may then dissipate as the time-varying electric fields of the beam become stronger. |
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FRPMN117 | Pepper-pot Based Emittance Measurements of the AWA Photoinjector | emittance, gun, space-charge, laser | 4393 | |||||
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The Argonne Wakefield Accelerator (AWA) RF photocathode gun is a 1.5 cell, L-band, RF photocathode gun operating at 80 MV/m, with an emittance compensating solenoid, and a magnesium photocathode and generates an 8 MeV, 1 nC - 100 nC beam. In this paper, we report on a parametric set of measurements to characterize the transverse trace space of the 1 nC electron beam directly out of the gun. The entire experiment is simulated with PARMELA, from the photocathode, through the pepper pot, and to the imaging screen. The transverse trace-space is sampled with a 2-D pepper pot which allows for simultaneous, single-shot measurements, of both the x and y distributions. A series of pepper pots were available during the experiment to increase the dynamic range of emittance measurements. Realistic particle distributions are used for the simulations and are derived from actual laser profiles, which were captured from a virtual cathode and generated with MATLAB-based particle generator. We report both the second moment (emittance) and the detailed phase space distribution over a gun launch phase range of approximately 50 degrees.
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FRPMN119 | Vector Processing Enhancements for Real-Time Image Analysis | controls, diagnostics, photon | 4399 | |||||
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Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. |
A real-time image analysis system was developed for beam imaging diagnostics. An Apple Power Mac G5 with an Active Silicon LFG frame grabber were used to capture video images that were processed and analyzed. Software routines were created to utilize vector processing hardware to reduce the time to process images as compared to conventional methods. These improvements allow for more advanced image processing diagnostics to be performed in real time. |
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FRPMS011 | Design of an Electro-Optical Sampling Experiment at the AWA Facility | laser, electron, monitoring, alignment | 3901 | |||||
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Funding: Supported by US DOE |
The free space electro-optical (EO) sampling technique is a powerful tool for analyzing the longitudinal charge density of an ultrashort e-beam. In this paper, we present * Yuelin Li, Appl. Phys. Lett. 88, 251108, 2006 |
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FRPMS047 | Design and Implementation of an Electron and Positron Multibunch Turn-by-Turn Vertical Beam Profile Monitor in CESR | electron, positron, synchrotron, radiation | 4081 | |||||
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Funding: This work is supported by the National Science Foundation. |
A fast vertical beam profile monitor has been implemented at the Cornell Electron Storage Ring (CESR). Readout is based on the Hamamatsu H7260K multianode photomultiplier. This device has a 32 channel linear anode array with 1 mm channel pitch and sub-nanosecond rise time. It provides the ability to probe individual electron and position bunches which are separated by 14 ns within the trains in CESR. A custom 72 MHz digitizer unit allows synchronous multibunch and turn-by-turn data acquisition. An on-board digital signal processor provides local data processing capability. This system provides the capability to probe a range of single bunch and multibunch beam dynamics issues as well as machine stability issues. In this paper we describe the profile monitor hardware, data acquisition system, calibration of the profile monitor, and data analysis software. |
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FRPMS093 | Numerical Studies of the Electromagnetic Weibel Instability in Intense Charged Particle Beams with Large Temperature Anisotropy Using the Nonlinear BEST Darwin Delta-f Code | plasma, simulation, electron, heavy-ion | 4297 | |||||
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Funding: Research supported by the U. S.Department of Energy. |
A numerical scheme for the electromagnetic particle simulation of high-intensity charged-particle beams has been developed which is a modification of the Darwin model. The Darwin model neglects the transverse induction current in Ampere?s law and therefore eliminates fast electromagnetic (light) waves from the simulations. The model has been incorporated into the nonlinear delta-f Beam Equilibrium Stability and Transport(BEST) code. As a benchmark, we have applied the model to simulate the transverse electromagnetic Weibel-type instability in a single-species charged-particle beam with large temperature anisotropy. Results are compared with previous theoretical and numerical studies using the eighenmode code bEASt. The nonlinear stage of the Weibel instability is also studied using BEST code, and the mechanism for nonlinear saturation is identified. |
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FRPMS112 | Absolute Measurement of the Polarization of High Energy Proton Beams at RHIC | polarization, proton, scattering, target | 4369 | |||||
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Funding: Work supported by the Department of Energy Contract no. DE-AC02-98CH10886 and the RIKEN BNL Research Center. |
The spin physics program at the Relativistic Heavy Ion Collider (RHIC) requires knowledge of the proton beam polarization to better than 5%. To achieve this goal, a polarized hydrogen jet target was installed in RHIC where it intersects both beams. The premise is to utilize the precise knowledge of the jet proton polarization to measure the analyzing power in the proton - proton elastic scattering process in the Coulomb Nuclear Interference (CNI) region at the prescribed RHIC proton beam energy, then use the reverse reaction to measure the degree of the beam polarization, and finally confront the results with simultaneous measurements by the fast high statistics polarimeter that measure the p-Carbon elastic scattering process in the CNI region to calibrate the latter. In this presentation, the polarized jet target mechanics, operation, detector systems and the p-Carbon polarimeter are described. The statistical accuracy attained as well as the systematic uncertainties will be discussed. Such techniques may well become the standard for high energy polarized proton beams planned elsewhere in Russia and Japan. |
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