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First Beam Measurements with the LHC Synchrotron Light Monitors

Description: The continuous monitoring of the transverse sizes of the beams in the Large Hadron Collider (LHC) relies on the use of synchrotron radiation and intensified video cameras. Depending on the beam energy, different synchrotron light sources must be used. A dedicated superconducting undulator has been built for low beam energies (450 GeV to 1.5 TeV), while edge and centre radiation from a beam-separation dipole magnet are used respectively for intermediate and high energies (up to 7 TeV). The emitt… more
Date: July 13, 2012
Creator: Lefevre, Thibaut; Bravin, Enrico; Burtin, Gerard; Guerrero, Ana; Jeff, Adam; Rabiller, Aurelie et al.
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Partner: UNT Libraries Government Documents Department
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Mysterious dipole synchrotron oscillations during and after adiabatic capture

Description: Strong synchrotron oscillations were observed during and after the 2.5-MHz rf adiabatic capture of a debunched booster batch in the Main Injector. Analysis shows two possible sources for the synchrotron oscillations. One is the frequency drift of the 2.5-MHz rf after the turning off of the 53-MHz rf voltage, thus resulting in an energy mismatch with the debunched beam. The second source is the energy mismatch of the injected booster beam with the frequency of the 53-MHz rf. We have been able to… more
Date: March 1, 2012
Creator: Ng, King-Yuen
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A Linac Simulation Code for Macro-Particles Tracking and Steering Algorithm Implementation

Description: In this paper, a linac simulation code written in Fortran90 is presented and several simulation examples are given. This code is optimized to implement linac alignment and steering algorithms, and evaluate the accelerator errors such as RF phase and acceleration gradient, quadrupole and BPM misalignment. It can track a single particle or a bunch of particles through normal linear accelerator elements such as quadrupole, RF cavity, dipole corrector and drift space. One-to-one steering algorithm … more
Date: May 3, 2012
Creator: sun, yipeng
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Effect of Field Errors in Muon Collider IR Magnets on Beam Dynamics

Description: In order to achieve peak luminosity of a Muon Collider (MC) in the 10{sup 35} cm{sup -2}s{sup -1} range very small values of beta-function at the interaction point (IP) are necessary ({beta}* {le} 1 cm) while the distance from IP to the first quadrupole can not be made shorter than {approx}6 m as dictated by the necessity of detector protection from backgrounds. In the result the beta-function at the final focus quadrupoles can reach 100 km making beam dynamics very sensitive to all kind of err… more
Date: May 1, 2012
Creator: Alexahin, Y.; Gianfelice-Wendt, E.; Kapin, V.V. & /Fermilab
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Partner: UNT Libraries Government Documents Department
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HOM identification by bead pulling in the Brookhaven ERL cavity

Description: Several past measurements of the Brookhaven ERL at superconducting temperature produced a long list of higher order modes (HOMs). The Niobium 5-cell cavity is terminated with HOM ferrite dampers that successfully reduce the Q-factors to tolerable levels. However, a number of undamped resonances with Q {ge} 10{sup 6} were found at 4 K and their mode identification remained as a goal for this paper. The approach taken here consists in taking different S{sub 21} measurements on a copper cavity rep… more
Date: June 25, 2012
Creator: Hahn, H.; Calaga, R.; Jain, P.; Johnson, E. C. & Xu, W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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RHIC spin flipper commissioning results

Description: The five AC dipole RHIC spin flipper design in the RHIC Blue ring was first tested during the RHIC 2012 polarized proton operation. The advantage of this design is to eliminate the vertical coherent betatron oscillations outside the spin flipper. The closure of each ac dipole vertical bump was measured with orbital response as well as spin. The effect of the rotating field on the spin motion by the spin flipper was also confirmed by measuring the suppressed resonance at Q{sub s} = 1 - Q{sub osc… more
Date: May 20, 2012
Creator: M., Bai; Roser, T.; Dawson, C.; Kewisch, J.; Makdisi, Y.; Oddo, P. et al.
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Partner: UNT Libraries Government Documents Department
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Measurements of the persistent current decay and snapback effect in Nb3Sn Fermilab-built accelerator prototype magnets

Description: In recent years, Fermilab has been performing an intensive R an D program on Nb{sub 3}Sn accelerator magnets. This program has included dipole and quadrupole magnets for different programs and projects, including LARP and VLHC. A systematic study of the persistent current decay and snapback effect in the fields of these magnets was executed at the Fermilab Magnet Test Facility. The decay and snapback were measured under a range of conditions including variations of the current ramp parameters a… more
Date: May 1, 2012
Creator: Velev, G. V.; Chlachidze, G.; DiMarco, J. & Kashikhin, V. V.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Advances in X-Band TW Accelerator Structures Operating in the 100 MV/M Regime

Description: A CERN-SLAC-KEK collaboration on high gradient X-band accelerator structure development for CLIC has been ongoing for three years. The major outcome has been the demonstration of stable 100 MV/m gradient operation of a number of CLIC prototype structures. These structures were fabricated using the technology developed from 1994 to 2004 for the GLC/NLC linear collider initiative. One of the goals has been to refine the essential parameters and fabrication procedures needed to realize such a high… more
Date: July 5, 2012
Creator: Higo, Toshiyasu; Higashi, Yasuo; Matsumoto, Shuji; Yokoyama, Kazue; Adolphsen, Chris; Dolgashev, Valery et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Higher Order Modes HOM___s in Coupled Cavities of the Flash Module ACC39

Description: We analyse the higher order modes (HOM's) in the 3.9GHz bunch shaping cavities installed in the FLASH facility at DESY. A suite of finite element computer codes (including HFSS and ACE3P) and globalised scattering matrix calculations (GSM) are used to investigate the modes in these cavities. This study is primarily focused on the dipole component of the multiband expansion of the wakefield, with the emphasis being on the development of a HOM-based BPM system for ACC39. Coupled inter-cavity mode… more
Date: September 14, 2012
Creator: Shinton, I. R. R.; Jones, R. M.; Li, Z. & Zhang, P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Beam optics and the pp2pp experiment at RHIC

Description: The newly installed forward detector system at the STAR experiment at RHIC measures small angle elastic and inelastic scattering of polarized protons on polarized protons. The detector system makes use of a pair of Roman Pot (RP) detectors, instrumented with silicon detectors, and located on either side of the STAR intersection region downstream of the DX and D0 dipoles and quadrupole triplets. The parallel to point optics is designed so that scattering angles are determined from position measu… more
Date: May 20, 2012
Creator: H., Pile P.; Guryn, W.; Lee, J. H.; Tepikian, S. & Yip, K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Observation of Instabilities of Coherent Transverse Oscillations in the Fermilab Booster

Description: The Fermilab Booster - built more than 40 years ago - operates well above the design proton beam intensity of 4 {center_dot} 10{sup 12} ppp. Still, the Fermilab neutrino experiments call for even higher intensity exceeding 5.5 {center_dot} 10{sup 12} ppp. A multitude of intensity related effects must be overcome in order to meet this goal including suppression of coherent dipole instabilities of transverse oscillations which manifest themselves as a sudden drop in the beam current. In this repo… more
Date: May 1, 2012
Creator: Alexahin, Y.; Eddy, N.; Gianfelice-Wendt, E.; Lebedev, V.; Marsh, W.; Pellico, W. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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ELECTRON POLARIZATION IN THE MEDIUM-ENERGY ELECTRON-ION COLLIDER AT JLAB

Description: A key feature of the Medium-energy Electron-Ion Collider (MEIC) at Jefferson Lab is high polarization (over 80%) of the electron beam at all collision points for the particle physics program. The equilibrium electron polarization is arranged to be vertical in the arcs of the figure-8 collider ring of the MEIC and anti-parallel to the arc dipole magnetic fields, in order to take advantage of the preservation of polarization by the Sokolov-Ternov (S-T) effect. Longitudinal polarization is achieve… more
Date: July 1, 2012
Creator: Fanglei Lin, Yaroslav Derbenev, Vasiliy Morozov, Yuhong Zhang, Desmond Barber
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Design Studies of a Dipole with Elliptical Aperture for the Muon Collider Storage Ring

Description: In this paper we describe the main design issues of dipoles with an elliptical aperture taking into consideration the field and field quality. The discussion is extended presenting a combined function magnet design. The temperature margin and the forces in the coils are present as well.
Date: May 1, 2012
Creator: Palmer, R. B.; Lopes, M. L.; Kashikhin, V. V.; Tompkins, J. C. & Zlobin, A. V.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Tevatron End-of-Run Beam Physics Experiments

Description: Before the Tevatron Collider Run II ended in September of 2011, a number of specialized beam study periods were dedicated to the experiments on various accelerator physics concepts and effects during the last year of the machine operation. The study topics included collimation with bent crystals and hollow electron beams, diffusion measurements and various aspects of beam-beam interactions. In this report we concentrate on the subject of beam-beam interactions, summarizing the results of beam e… more
Date: May 1, 2012
Creator: Valishev, A.; Gu, X.; Miyamoto, R.; White, S.; Schmidt, F. & Qiang, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Improving PbS Quantum Dot Solar Cell Power Conversion Efficiency to an NREL-Certified 4.4% (Fact Sheet)

Description: Transition metal oxide improves overall efficiency and maintains performance with inexpensive metals. A research team at the National Renewable Energy Laboratory (NREL) has demonstrated that inserting a transition metal oxide (TMO) between the lead sulfide (PbS) quantum dot (QD) layer and the metal electrode eliminates the Schottky barrier that impedes efficient hole extraction and thereby improves the overall conversion efficiency. This allows for inexpensive metals such as Al to be employed w… more
Date: January 1, 2012
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Optimization of AC Dipole Parameters for the Mu2e Extinction System

Description: The Mu2e experiment is being planned at Fermilab to measure the rate for muons to convert to electrons in the field of an atomic nucleus with unprecedented precision. This experiment uses an 8 GeV primary proton beam consisting of short ({approx}200 nsec FW) bunches, separated by 1.7 {mu}sec. It is vital that out-of-bunch beam be suppressed at the level of 10{sup -10} or less. This poster describes the parametric analysis which was done to determine the optimum harmonics and magnet specificatio… more
Date: May 1, 2012
Creator: Prebys, E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Momentum Cogging at the Fermilab Booster

Description: The Fermilab Booster has an upgrade plan called the Proton Improvement Plan (PIP). The flux throughput goal is 2E17 protons/hour which, is almost double the present flux, 1.1E17 protons/hour. The beam loss in the machine is going to be an issue. The Booster accelerates beam from 400 MeV to 8 GeV and extracts to the Main Injector (MI). The current cogging process synchronizes the extraction kicker gap to the MI by changing radial position of the beam during the cycle. The gap creation occurs at … more
Date: May 1, 2012
Creator: Seiya, K.; Drennan, C.; Pellico, W. A.; Triplett, K. & Waller, A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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CSR in the SuperKEKB Damping Ring

Description: Coherent synchrotron radiation (CSR) is generated when a bunched beam traverses a dipole magnet or a wiggler/undulator. It can degrade the beam quality in both storage rings and linacs through enhancing the beam energy spread and lengthening the bunch length, even cause single-bunch microwave instabilities. Using several methods, CSR impedances in the positron damping ring (DR) of the SuperKEKB which is under design were calculated. From the impedances due to CSR, resistive wall and various vac… more
Date: July 6, 2012
Creator: Zhou, Demin; Abe, Tetsuo; Ikeda, Hitomi; Kikuchi, Mitsuo; Ohmi, Kazuhito; Oide, Katsunobu et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The Jefferson Lab Frozen Spin Target

Description: A frozen spin polarized target, constructed at Jefferson Lab for use inside a large acceptance spectrometer, is described. The target has been utilized for photoproduction measurements with polarized tagged photons of both longitudinal and circular polarization. Protons in TEMPO-doped butanol were dynamically polarized to approximately 90% outside the spectrometer at 5 T and 200-300 mK. Photoproduction data were acquired with the target inside the spectrometer at a frozen-spin temperature of ap… more
Date: August 1, 2012
Creator: Christopher Keith, James Brock, Christopher Carlin, Sara Comer, David Kashy, Josephine McAndrew, David Meekins, Eugene Pasyuk, Joshua Pierce, Mikell Seely
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Linear Fixed-Field Multi-Pass Arcs for Recirculating Linear Accelerators

Description: Recirculating Linear Accelerators (RLA's) provide a compact and efficient way of accelerating particle beams to medium and high energies by reusing the same linac for multiple passes. In the conventional scheme, after each pass, the different energy beams coming out of the linac are separated and directed into appropriate arcs for recirculation, with each pass requiring a separate fixed-energy arc. In this paper we present a concept of an RLA return arc based on linear combined-function magnets… more
Date: June 1, 2012
Creator: V.S. Morozov, S.A. Bogacz, Y.R. Roblin, K.B. Beard
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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High-power Waveguide Dampers for the Short-Pulse X-Ray Project at the Advanced Photon Source

Description: High-power waveguide dampers have been designed and prototyped for the Short-Pulse X-ray (SPX) cavities at the Advanced Photon Source. The cavities will operate at 2.815 GHz and utilize the TM110 dipole mode. As a result, higher-order (HOM) and lower-order mode (LOM) in-vacuum dampers have been designed to satisfy the demanding broadband damping requirements in the APS storage ring. The SPX single-cell cavity consists of two WR284 waveguides for damping the HOMs and one WR284 waveguide for prim… more
Date: July 1, 2012
Creator: Waldschmidt, G. J.; Liu, J.; Middendorf, M. E.; Nassiri, A.; Smith, T. L.; Wu, G..= et al.
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Partner: UNT Libraries Government Documents Department
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Novel Slow Extraction Scheme for Proton Accelerators Using Pulsed Dipole Correctors and Crystals

Description: Slow extraction of protons beams from circular accelerators is currently widely used for a variety of beam-based experiments. The method has some deficiencies including limited efficiency of extraction, radiation induced due to scattering on the electrostatic septa and limited beam pipe aperture, beam dynamics effects of space charge forces and magnet power supplies ripple. Here we present a novel slow extraction scheme employing a number of non-standard accelerator elements, such as Silicone c… more
Date: May 1, 2012
Creator: Shiltsev, V.
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Partner: UNT Libraries Government Documents Department
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Precision Magnet Measurements for X-Band Accelerator Quadrupole Triplets

Description: An X-band test station is being developed at LLNL to investigate accelerator optimization for future upgrades to mono-energetic gamma-ray (MEGa-Ray) technology at LLNL. Beamline magnets will include an emittance compensation solenoid, windowpane steering dipoles, and quadrupole magnets. Demanding tolerances have been placed on the alignment of these magnets, which directly affects the electron bunch beam quality. A magnet mapping system has been established at LLNL in order to ensure the delive… more
Date: May 16, 2012
Creator: Marsh, R A; Anderson, S G & Armstrong, J P
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Partner: UNT Libraries Government Documents Department
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Photoelectronic characterization of heterointerfaces.

Description: In many devices such as solar cells, light emitting diodes, transistors, etc., the performance relies on the electronic structure at interfaces between materials within the device. The objective of this work was to perform robust characterization of hybrid (organic/inorganic) interfaces by tailoring the interfacial region for photoelectron spectroscopy. Self-assembled monolayers (SAM) were utilized to induce dipoles of various magnitudes at the interface. Additionally, SAMs of molecules with va… more
Date: February 1, 2012
Creator: Brumbach, Michael Todd
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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