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Conversion of a transverse density modulation into a longitudinal phase space modulation using an emittance exchange technique

Description: We report on an experiment to produce a train of sub-picosecond microbunches using a transverse-to-longitudinal emittance exchange technique. The generation of a modulation on the longitudinal phase space is done by converting an initial horizontal modulation produced using a multislits mask. The preliminary experimental data clearly demonstrate the conversion process. To date only the final energy modulation has been measured. However numerical simulations, in qualitative agreement with the me… more
Date: March 1, 2010
Creator: Sun, Y. E.; Piot, P.; Johnson, A.; Lumpkin, A.; Ruan, J. & Thurman-Keup, R.
Partner: UNT Libraries Government Documents Department
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Rapid Cycling Synchrotron Option for Project X

Description: This paper presents an 8 GeV Rapid Cycling Synchrotron (RCS) option for Project X. It has several advantages over an 8 GeV SC linac. In particular, the cost could be lower. With a 2 GeV 10 mA pulsed linac as injector, the RCS would be able to deliver 4 MW beam power for a muon collider. If, instead, a 2 GeV 1 mA CW linac is used, the RCS would still be able to meet the Project X requirements but it would be difficult for it to serve a muon collider due to the very long injection time.
Date: December 1, 2009
Creator: Chou, Weiren
Partner: UNT Libraries Government Documents Department
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Tunable subpicosecond electron bunch train generation using a transverse-to-longitudinal phase space exchange technique

Description: We report on the experimental generation of a train of subpicosecond electron bunches. The bunch train generation is accomplished using a beamline capable of exchanging the coordinates between the horizontal and longitudinal degrees of freedom. An initial beam consisting of a set of horizontally-separated beamlets is converted into a train of bunches temporally separated with tunable bunch duration and separation. The experiment reported in this Letter unambiguously demonstrates the conversion … more
Date: November 1, 2010
Creator: Sun, Y. E.; Piot, P.; Johnson, A.; Lumpkin, A. H.; Maxwell, T. J.; Ruan, J. et al.
Partner: UNT Libraries Government Documents Department
open access

First observation of the exchange of transverse and longitudinal emittances

Description: An experimental program to demonstrate a novel phase space manipulation in which the horizontal and longitudinal emittances of a particle beam are exchanged has been completed at the Fermilab A0 Photoinjector. A new beamline, consisting of a TM{sub 110} deflecting mode cavity flanked by two horizontally dispersive doglegs has been installed. We report on the first direct observation of transverse and longitudinal emittance exchange: {l_brace}{var_epsilon}{sub x}{sup n}, {var_epsilon}{sub y}{sup… more
Date: February 1, 2011
Creator: Ruan, J.; Johnson, A. S.; Lumpkin, A. H.; Thurman-Keup, R.; Edwards, H.; Fliller, R. P. et al.
Partner: UNT Libraries Government Documents Department
open access

Head-Tail Modes for Strong Space Charge

Description: Head-tail modes are described here for the space charge tune shift significantly exceeding the synchrotron tune. General equation for the modes is derived. Spatial shapes of the modes, their frequencies, and coherent growth rates are explored. The Landau damping rates are also found. Suppression of the transverse mode coupling instability by the space charge is explained.
Date: December 1, 2008
Creator: Burov, Alexey
Partner: UNT Libraries Government Documents Department
open access

CMS Data Processing Workflows during an Extended Cosmic Ray Run

Description: The CMS Collaboration conducted a month-long data taking exercise, the Cosmic Run At Four Tesla, during October-November 2008, with the goal of commissioning the experiment for extended operation. With all installed detector systems participating, CMS recorded 270 million cosmic ray events with the solenoid at a magnetic field strength of 3.8 T. This paper describes the data flow from the detector through the various online and offline computing systems, as well as the workflows used for record… more
Date: November 1, 2009
Partner: UNT Libraries Government Documents Department
open access

Generation of Relativistic Electron Bunches with Arbitrary Current Distribution via Transverse-to-Longitudinal Phase Space Exchange

Description: We propose a general method for tailoring the current distribution of relativistic electron bunches. The technique relies on a recently proposed method to exchange the longitudinal phase space emittance with one of the transverse emittances. The method consists of transversely shaping the bunch and then converting its transverse profile into a current profile via a transverse-to-longitudinal phase-space-exchange beamline. We show that it is possible to tailor the current profile to follow, in p… more
Date: July 1, 2010
Creator: Piot, P.; Sun, Y. E.; Power, J. G. & Rihaoui, M.
Partner: UNT Libraries Government Documents Department
open access

Transverse Instabilities of Coasting Beams with Space Charge

Description: Transverse beam stability is strongly affected by the beam space charge. Usually it is analyzed with the rigid-beam model. However this model is only valid when a bare (not affected by the space charge) tune spread is small compared to the space charge tune shift. This condition specifies a relatively small area of parameters which, however, is the most interesting for practical applications. The Landau damping rate and the beam Schottky spectra are computed assuming that validity condition is … more
Date: December 1, 2008
Creator: Burov, Alexey & Lebedev, Valeri
Partner: UNT Libraries Government Documents Department
open access

Photoluminescence of Diamondoid Crystals

Description: The photoluminescence of diamondoids in the solid state is examined. All of the diamondoids are found to photoluminesce readily with initial excitation wavelengths ranging from 233 nm to 240 nm (5.3 eV). These excitation energies are more than 1 eV lower than any previously studied saturated hydrocarbon material. The emission is found to be heavily shifted from the absorption, with emission wavelengths of roughly 295 nm (4.2 eV) in all cases. In the dissolved state, however, no uorescence is ob… more
Date: April 3, 2012
Creator: Clay, William; /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept. /Stanford U., Geballe Lab.; Sasagawa, Takao; Iwasa, Akio; /TIT, Nagatsuta; Liu, Zhi et al.
Partner: UNT Libraries Government Documents Department
open access

Beam test of a segmented foil sem grid

Description: A prototype Secondary-electron Emission Monitor (SEM) was installed in the 8 GeV proton transport line for the MiniBooNE experiment at Fermilab. The SEM is a segmented grid made with 5 {micro}m Ti foils, intended for use in the 120 GeV NuMI beam at Fermilab. Similar to previous workers, we found that the full collection of the secondary electron signal requires a bias voltage to draw the ejected electrons cleanly off the foils, and this effect is more pronounced at larger beam intensity. The be… more
Date: July 1, 2005
Creator: Kopp, S.; Indurthy, D.; Pavlovich, Z.; Proga, M.; Zwaska, R.; Childress, S. et al.
Partner: UNT Libraries Government Documents Department
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