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GPU-optimized Code for Long-term Simulations of Beam-beam Effects in Colliders

Description: We report on the development of the new code for long-term simulation of beam-beam effects in particle colliders. The underlying physical model relies on a matrix-based arbitrary-order symplectic particle tracking for beam transport and the Bassetti-Erskine approximation for beam-beam interaction. The computations are accelerated through a parallel implementation on a hybrid GPU/CPU platform. With the new code, a previously computationally prohibitive long-term simulations become tractable. We use the new code to model the proposed medium-energy electron-ion collider (MEIC) at Jefferson Lab.
Date: June 1, 2013
Creator: Roblin, Yves; Morozov, Vasiliy; Terzic, Balsa; Aturban, Mohamed A.; Ranjan, D. & Zubair, Mohammed
Partner: UNT Libraries Government Documents Department
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Development of Ultra High Gradient and High Q{sub 0} Superconducting Radio Frequency Cavities

Description: We report on the recent progress at Jefferson Lab in developing ultra high gradient and high Q{sub 0} superconducting radio frequency (SRF) cavities for future SRF based machines. A new 1300 MHz 9-cell prototype cavity is being fabricated. This cavity has an optimized shape in terms of the ratio of the peak surface field (both magnetic and electric) to the acceleration gradient, hence the name low surface field (LSF) shape. The goal of the effort is to demonstrate an acceleration gradient of 50 MV/m with Q{sub 0} of 10{sup 10} at 2 K in a 9-cell SRF cavity. Fine-grain niobium material is used. Conventional forming, machining and electron beam welding method are used for cavity fabrication. New techniques are adopted to ensure repeatable, accurate and inexpensive fabrication of components and the full assembly. The completed cavity is to be first mechanically polished to a mirror-finish, a newly acquired in-house capability at JLab, followed by the proven ILC-style processing recipe established already at JLab. In parallel, new single-cell cavities made from large-grain niobium material are made to further advance the cavity treatment and processing procedures, aiming for the demonstration of an acceleration gradient of 50 MV/m with Q{sub 0} of 2�10{sup 10} at 2K.
Date: June 1, 2013
Creator: Geng, Rongli; Clemens, William A.; Follkie, James E.; Harris, Teena M.; Kushnick, Peter W.; Machie, Danny et al.
Partner: UNT Libraries Government Documents Department
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Improvements to Existing Jefferson Lab Wire Scanners

Description: This poster will detail the augmentation of selected existing CEBAF wire scanners with commercially available hardware, PMTs, and self created software in order to improve the scanners both in function and utility.
Date: June 1, 2013
Creator: McCaughan, Michael D.; Tiefenback, Michael G. & Turner, Dennis L.
Partner: UNT Libraries Government Documents Department
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The Scheme of Beam Synchronization in MEIC

Description: Synchronizing colliding beams at single or multiple collision points is a critical R&D issue in the design of a medium energy electron-ion collider (MEIC) at Jefferson Lab. The path-length variation due to changes in the ion energy, which varies over 20 to 100 GeV, could be more than several times the bunch spacing. The scheme adopted in the present MEIC baseline is centered on varying the number of bunches (i.e., harmonic number) stored in the collider ring. This could provide a set of discrete energies for proton or ions such that the beam synchronization condition is satisfied. To cover the ion energy between these synchronized values, we further propose to vary simultaneously the electron ring circumference and the frequency of the RF systems in both collider rings. We also present in this paper the requirement of frequency tunability of SRF cavities to support the scheme.
Date: June 1, 2013
Creator: Zhang, Yuhong; Derbenev, Yaroslav S. & Hutton, Andrew M.
Partner: UNT Libraries Government Documents Department
open access

The 12 GeV Energy Upgrade at Jefferson Laboratory

Description: Two new cryomodules and an extensive upgrade of the bending magnets at Jefferson Lab has been recently completed in preparation for the full energy upgrade in about one year. Jefferson Laboratory has undertaken a major upgrade of its flagship facility, the CW re-circulating CEBAF linac, with the goal of doubling the linac energy to 12 GeV. I will discuss here the main scope and timeline of the upgrade and report on recent accomplishments and the present status. I will then discuss in more detail the core of the upgrade, the new additional C100 cryomodules, their production, tests and recent successful performance. I will then conclude by looking at the future plans of Jefferson Laboratory, from the commissioning and operations of the 12 GeV CEBAF to the design of the MEIC electron ion collider.
Date: September 2012
Creator: Pilat, Fulvia C.
Partner: UNT Libraries Government Documents Department
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Qualification of the Second Batch Production 9-Cell Cavities Manufactured by AES and Validation of the First US Industrial Cavity Vendor for ILC

Description: One of the major goals of ILC SRF cavity R&D is to develop industrial capabilities of cavity manufacture and processing in all three regions. In the past several years, Jefferson Lab, in collaboration with Fermi National Accelerator Laboratory, has processed and tested all the 9-cell cavities of the first batch (4 cavities) and second batch (6 cavities) production cavities manufactured by Advanced Energy Systems Inc. (AES). Over the course, close information feedback was maintained, resulting in changes in fabrication and processing procedures. A light buffered chemical polishing was introduced, removing the weld splatters that could not be effectively removed by heavy EP alone. An 800 Celsius 2 hour vacuum furnace heat treatment procedure replaced the original 600 Celsius 10 hour procedure. Four out of the six 9-cell cavities of the second production bath achieved a gradient of 36-41 MV/m at a Q0 of more than 8E9 at 35 MV/m. This result validated AES as the first ''ILC certified'' industrial vendor in the US for ILC cavity manufacture.
Date: July 1, 2011
Creator: Geng, R. L.; Golden, B. A.; Kushnick, P.; Overton, R. B.; Calderaro, M.; Peterson, E. et al.
Partner: UNT Libraries Government Documents Department
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Workshops on Science Enabled by a Coherent, CW, Synchrotron X-ray Source, June 2011

Description: In June of 2011 we held six two-day workshops called "XDL-2011: Science at the Hard X-ray Diffraction Limit". The six workshops covered (1) Diffraction-based imaging techniques, (2) Biomolecular structure from non-crystalline materials, (3) Ultra-fast science, (4) High-pressure science, (5) Materials research with nano-beams and (6) X-ray photon correlation spectroscopy (XPCS), In each workshop, invited speaker from around the world presented examples of novel experiments that require a CW, diffraction-limited source. During the workshop, each invited speaker provided a one-page description of the experiment and an illustrative graphic. The experiments identified by the workshops demonstrate the broad and deep scientific case for a CW coherent synchrotron x-ray source. The next step is to perform detailed simulations of the best of these ideas to test them quantitatively and to guide detailed x-ray beam-line designs. These designs are the first step toward developing detailed facility designs and cost estimates.
Date: January 3, 2012
Creator: Brock, Joel
Partner: UNT Libraries Government Documents Department
open access

Preparation and Testing of the SRF Cavities for the CEBAF 12 GeV Upgrade

Description: Eighty new 7-cell, low-loss cell-shaped cavities are required for the CEBAF 12 GeV Upgrade project. In addition to ten pre-production units fabricated at JLab, the full set of commercially-produced cavities have been delivered. An efficient processing routine, which includes a controlled 30 micron electropolish, has been established to transform these cavities into qualified 8-cavity strings. This work began in 2010 and will run through the end of 2011. The realized cavity performance consistently exceeds project requirements and also the maximum useful gradient in CEBAF: 25 MV/m. We will describe the cavity processing and preparation protocols and summarize test results obtained to date.
Date: July 1, 2011
Creator: Reilly, A. V.; Bass, T.; Burrill, A.; Davis, G. K.; Marhauser, F.; Reece, C. E. et al.
Partner: UNT Libraries Government Documents Department
open access

Novel Geometries for the LHC Crab Cavity

Description: The planned luminosity upgrade to LHC is likely to necessitate a large crossing angle and a local crab crossing scheme. For this scheme crab cavities align bunches prior to collision. The scheme requires at least four such cavities, a pair on each beam line either side of the interaction point (IP). Upstream cavities initiate rotation and downstream cavities cancel rotation. Cancellation is usually done at a location where the optics has re-aligned the bunch. The beam line separation near the IP necessitates a more compact design than is possible with elliptical cavities such as those used at KEK. The reduction in size must be achieved without an increase in the operational frequency to maintain compatibility with the long bunch length of the LHC. This paper proposes a suitable superconducting variant of a four rod coaxial deflecting cavity (to be phased as a crab cavity), and presents analytical models and simulations of suitable designs.
Date: May 1, 2010
Creator: B. Hall,G. Burt,C. Lingwood,Robert Rimmer,Haipeng Wang; Hall, B.; Burt, G.; Lingwood, C.; Rimmer, Robert & Wang, Haipeng
Partner: UNT Libraries Government Documents Department
open access

A New Approach to Improving the Efficiency of FEL Oscillator Simulations

Description: During the last year we have been benchmarking FEL oscillator simulation codes against the measured performance of the three Jefferson Lab oscillator FELs. While one might think that a full 4D simulation is de facto the best predictor of performance, the simulations are computationally intensive, even when analytical approximations to the electron bunch longitudinal distribution are used. In this presentation we compare the predictions of the 4D FEL interaction codes Genesis and Medusa, in combination with the optical code OPC, with those using a combination of the 2D & 3D versions of these codes, which can be run quickly on a single CPU core desktop computer.
Date: May 1, 2013
Creator: Shinn, Michelle D.; Benson, Stephen V.; Watson, Anne M.; Freund, Henry P.; Nyugen, Dinh C. & van der Slot, Peter J.M.
Partner: UNT Libraries Government Documents Department
open access

Cryogenic targets for electron scattering

Description: Over the past few years we have developed a system which allows several different liquid hydrogen and liquid deuterium targets to be placed in the electron beam of the Stanford Mark III accelerator and which can be operated from a remote position. The geometry of our scattering chamber requires that the motion (of the various targets into position) must be in the vertical direction, but that the overall height of the system be constant. These requirements are met by using an internal retractable bellows arrangement to raise and lower the target cells. As many as five cells can be used in conjunction with a single reservoir system.
Date: June 1, 1963
Creator: Chambers, B.; Hofstadter, R.; Marcum, A. & Yearian, M. R.
Partner: UNT Libraries Government Documents Department
open access

An Accumulator/Pre-Booster for the Medium-Energy Electron Ion Collider at Jlab

Description: Future nuclear physics facilities such as the proposed electron ion collider (MEIC) will need to achieve record high luminosities in order to maximize discovery potential. Among the necessary ingredients is the ability to generate, accumulate , accelerate, and store high current ion beams from protons to lead ions. One of the main components of this ion accelerator complex for MEIC chain is the accumulator that also doubles as a pre-booster, which takes 200 MeV protons from a superconducting linear accelerator, accumulates on the order of 1A beam, and boosts its energy to 3GeV, before extraction to the next accelerator in the chain, the large booster. This paper describes its design concepts, and summarizes some preliminary results, including linear optics, space charge dynamics, and spin polarization resonance analysis.
Date: April 1, 2011
Creator: Erdelyi, B.; Manikonda, S. L.; Ostroumov, P. N.; Abeyratne, S.; Derbenev, Y. S.; Krafft, G. A. et al.
Partner: UNT Libraries Government Documents Department
open access

LEIC - A Polarized Low Energy Electron-ion Collider at Jefferson Lab

Description: A polarized electron-ion collider is envisioned as the future nuclear science program at JLab beyond the 12 GeV CEBAF. Presently, a medium energy collider (MEIC) is set as an immediate goal with options for a future energy upgrade. A comprehensive design report for MEIC has been released recently. The MEIC facility could also accommodate electron and proton/ion collisions in a low CM energy range, covering proton energies from 10 to 25 GeV and ion energies with a similar magnetic rigidity, for additional science reach. In this paper, we present a conceptual design of this low energy collider, LEIC, showing its luminosity can reach above 10{sup 33} cm{sup -2}s{sup -1}. The design specifies that the large booster of the MEIC is converted to a low energy ion collider ring with an interaction region and an electron cooler integrated into it. The design provides options for either sharing the detector with the MEIC or a dedicated low energy detector in a third collision point, with advantages of either a minimum cost or extra detection parallel to the MEIC operation, respectively. The LEIC could be positioned as the first and low cost phase of a multi-stage approach to realize the full MEIC.
Date: June 1, 2013
Creator: Derbenev, Yaroslav S.; Hutton, Andrew M.; Krafft, Geoffrey A.; Li, Rui; Lin, Fanglei; Morozov, Vasiliy et al.
Partner: UNT Libraries Government Documents Department
open access

Electron Cloud at Low Emittance in CesrTA

Description: The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud's effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results.
Date: May 23, 2010
Creator: Alexander, J. P.; Billing, M. G.; Calvey, J.; Crittenden, J. A.; Dugan, G.; Eggert, N. et al.
Partner: UNT Libraries Government Documents Department
open access

Vibration Response Testing of the CEBAF 12GeV Upgrade Cryomodules

Description: The CEBAF 12 GeV upgrade project includes 80 new 7-cell cavities to form 10 cryomodules. These cryomodules were tested during production to characterize their microphonic response in situ. For several early cryomodules, detailed (vibration) modal studies of the cryomodule string were performed during the assembly process to identify the structural contributors to the measured cryomodule microphonic response. Structural modifications were then modelled, implemented, and verified by subsequent modal testing and in-situ microphonic response testing. Interim and latest results from this multi-stage process will be reviewed.
Date: September 1, 2012
Creator: Davis, G. Kirk; Matalevich, Joseph R.; Wiseman, Mark A. & Powers, Thomas J.
Partner: UNT Libraries Government Documents Department
open access

A CONTINUOUS HIGH POWER BEAM DUMP OF THE HOT-DOG-COOKER TYPE

Description: A beam dump with partially rotating water-cooled tube arrays is proposed and studied for the dump of continuous high power density unneutralized ion beams out of the neutral beam injectors. Analyses were made of both steady and transient heat transfer characteristics.
Date: March 1, 1980
Creator: Yoshikawa, Kiyoshi
Partner: UNT Libraries Government Documents Department
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Particle beam self-modulation instability in tapered and inhomogeneous plasma

Description: The particle beam self-modulation instability in tapered and inhomogeneous plasmas is analyzed via an evolution equation for the beam radius. For a sufficiently fast taper the instability is suppressed, and the condition for growth suppression is derived. The form of the taper to phase lock a trailing witness bunch in the plasma wave driven by a self-modulated beam is determined, which can increase the energy gain by several orders of magnitude. Growth of the instability places stringent constraints on the initial background plasma density fluctuations.
Date: December 28, 2011
Creator: Schroeder, Carl; Benedetti, Carlo; Esarey, Eric; Gruener, Florian & Leemans, Wim
Partner: UNT Libraries Government Documents Department
open access

Where Next with SRF?

Description: RF superconductivity (SRF) has become, over the last ~20 years, the technology of choice to produce RF cavities for particle accelerators. This occurred because of improvements in material and processing techniques as well as the understanding and remediation of practical limitations in SRF cavities. This development effort span ~40 years and Nb has been the material of choice for SRF cavity production. As the performances of SRF Nb cavities are approaching what are considered to be theoretical limits of the material, it is legitimate to ask what will be the future of SRF. In this article we will attempt to answer this question on the basis of near-future demands for SRF-based accelerators and the basic SRF properties of the available materials. Clearly, Nb will continue to play a major role in SRF cavities in the coming years but the use of superconductors with higher critical temperature than Nb is also likely to occur.
Date: June 1, 2013
Creator: Ciovati, Gianluigi
Partner: UNT Libraries Government Documents Department
open access

JEMMRLA - Electron Model of a Muon RLA with Multi-pass Arcs

Description: We propose a demonstration experiment for a new concept of a 'dogbone' RLA with multi-pass return arcs -- JEMMRLA (Jlab Electron Model of Muon RLA). Such an RLA with linear-field multi-pass arcs was introduced for rapid acceleration of muons for the next generation of Muon Facilities. It allows for efficient use of expensive RF while the multi-pass arc design based on linear combined-function magnets exhibits a number of advantages over separate-arc or pulsed-arc designs. Here we describe a test of this concept by scaling a GeV scale muon design for electrons. Scaling muon momenta by the muon-to-electron mass ratio leads to a scheme, in which a 4.5 MeV electron beam is injected in the middle of a 3 MeV/pass linac with two double-pass return arcs and is accelerated to 18 MeV in 4.5 passes. All spatial dimensions including the orbit distortion are scaled by a factor of 7.5, which arises from scaling the 200 MHz muon RF to a readily available 1.5 GHz. The hardware requirements are not very demanding making it straightforward to implement. Such an RLA may have applications going beyond muon acceleration: in medical isotope production, radiation cancer therapy and homeland security.
Date: June 1, 2013
Creator: Bogacz, Slawomir Alex; Krafft, Geoffrey A.; Morozov, Vasiliy S. & Roblin, Yves R.
Partner: UNT Libraries Government Documents Department
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Measurements of Martin-Puplett Interferometer Limitations using Blackbody Source

Description: Frequency domain measurements with Martin-Puplett interferometer is one of a few techniques capable of bunch length measurements at the level of ~ 100 fs. As the bunch length becomes shorter, it is important to know and be able to measure the limitations of the instrument in terms of shortest measurable bunch length. In this paper we describe an experiment using a blackbody source with the modified Martin-Puplett interferometer that is routine- ly used for bunch length measurements at the JLab FEL, as a way to estimate the shortest, measurable bunch length. The limitation comes from high frequency cut-off of the wire-grid polarizer currently used and is estimated to be 50 fs RMS. The measurements are made with the same Golay cell detector that is used for beam measure- ments. We demonstrate that, even though the blackbody source is many orders of magnitude less bright than the coherent transition or synchrotron radiation, it can be used for the measurements and gives a very good signal to noise ratio in combination with lock-in detection. We also compare the measurements made in air and in vacuum to characterize the very strong effect of the atmospheric absorption.
Date: June 1, 2013
Creator: Evtushenko, Pavel E. & Klopf, John M.
Partner: UNT Libraries Government Documents Department
open access

STUDY OF THE STABILITY OF PARTICLE MOTION IN STORAGE RINGS. Final Report

Description: During this period, our research was concentrated on the study of beam-beam effects in large storage-ring colliders and coherent synchrotron radiation (CSR) effect in light sources. Our group was involved in and made significant contribution to several international accelerator projects such as the US-LHC project for the design of the LHC interaction regions, the luminosity upgrade of Tevatron and HERA, the design of eRHIC, and the U.S. LHC Accelerator Research Program (LARP) for the future LHC luminosity upgrade.
Date: September 7, 2012
Creator: Shi, Jack J.
Partner: UNT Libraries Government Documents Department
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Exploration of Quench Initiation Due to Intentional Geometrical Defects in a High Magnetic Field Region of an SRF Cavity

Description: A computer program which was used to simulate and analyze the thermal behaviors of SRF cavities has been developed at Jefferson Lab using C++ code. This code was also used to verify the quench initiation due to geometrical defects in high magnetic field region of SRF cavities. We built a CEBAF single cell cavity with 4 artificial defects near equator, and this cavity has been tested with T-mapping. The preheating behavior and quench initiation analysis of this cavity will be presented here using the computer program.
Date: July 1, 2011
Creator: J. Dai, K. Zhao, G.V. Eremeev, R.L. Geng, A.D. Palczewski; Dai, J.; Palczewski, A. D.; Eremeev, G. V.; Geng, R. L. & Zhao, K.
Partner: UNT Libraries Government Documents Department
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