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Antiproton Yields for Stochastic Accumulation

Description: Two sets of parameters have been developed to study stochastic accumulation. The question arises of the size of the transverse emittance required to achieve an antiproton yield of 1.2 x 10{sup 8} {bar p}'s/MR cyc1e for 4.5 GeV and 8 GeV {bar p} kinetic energies, given a full momentum acceptance of 4%. The results quoted in the paper are obtained with a Monte Carlo program which uses a fit to the {bar p} production invariant cross section that has been presented previously. An article describing the program is in preparation.
Date: July 15, 1981
Creator: Hojnat, Carlos & Ginneken, A.Van
Partner: UNT Libraries Government Documents Department

A Proposal to Continue Measurements of Direct Muon Production in the Forward Direction

Description: The authors recently have measured the direct muon production in the forward direction at small p{perpendicular} and find a large direct muon to pion ratio. At x = 0.3 the ratio is {mu}{sup -}/{pi}{sup -} = 1.83 {+-} 0.43 x 10{sup -4} for negatives and {mu}{sup +}/{pi}{sup +} = 6.4 {+-} 1.3 x 10{sup -5} for positives. The direct production of {mu}{sup +} and {mu}{sup -} are equal although the {pi}{sup +}/{pi}{sup -} ratios is large. They propose to continue these measurements and extend them to higher x. These new measurements would also include the A dependence of the {mu}/{pi} ratio. Based on their experience with this apparatus, they believe it is possible to extend these measurements of single lepton production to production by incident pions and kaons.
Date: October 20, 1975
Creator: Buchholz, D.; U., /Northwestern; Frisch, H.J.; Shochet, M.J.; /Chicago U., EFI; Johnson, Rolland P. et al.
Partner: UNT Libraries Government Documents Department

Subpicosecond electron bunch train production using a phase-space exchange technique

Description: Our recent experimental demonstration of a photoinjector electron bunch train with sub-picosecond structures is reported in this paper. The experiment is accomplished by converting an initially horizontal beam intensity modulation into a longitudinal phase space modulation, via a beamline capable of exchanging phase-space coordinates between the horizontal and longitudinal degrees of freedom. The initial transverse modulation is produced by intercepting the beam with a multislit mask prior to the exchange. We also compare our experimental results with numerical simulations.
Date: March 1, 2011
Creator: Sun, Y.-E.; /Fermilab; Piot, P.; U., /Fermilab /Northern Illinois; Johnson, A.S.; Lumpkin, A.H. et al.
Partner: UNT Libraries Government Documents Department

Two Jet Production at CDF

Description: CDF (Collider Detector at Fermilab) is a full-coverage magnetic detector studying p{bar p} collisions at the {radical}s = 1.8 TeV Tevatron Collider. The experiment has collected a handful of demonstration events towards the end 1985, and had its first significant run in spring 1987. Most of this run was operated with a 'buffet trigger', one stream of which was an inclusive large-E{sub t} trigger. Large E{sub t} (E{sub t} >50 GeV) events at the Tevatron show an increasingly dominant component with two or more hard jets. This thesis consists in an analysis of these jet events. The invariant cross-secton as a function of jet pair mass (M{sub jj}) is derived.
Date: January 1, 1989
Creator: Dell'Agnello, Simone
Partner: UNT Libraries Government Documents Department

Beam Losses in the Extraction Line of a TeV E+ E- Linear Collider With a 20-Mrad Crossing Angle

Description: In this paper, we perform a detailed study of the power losses along the postcollision extraction line of a TeV e+e- collider with a crossing angle of 20 mrad between the beams at the interaction point. Five cases are considered here: four luminosity configurations for ILC and one for CLIC. For all of them, the strong beam-beam effects at the interaction point lead to an emittance growth for the outgoing beams, as well as to the production of beamstrahlung photons and e+e- pairs. The power losses along the 20 mrad extraction line, which are due to energy deposition by a fraction of the disrupted beam, of the beamstrahlung photons and of the e+e- coherent pairs, were estimated in the case of ideal collisions, as well as with a vertical position or angular o set at the interaction point.
Date: March 29, 2006
Creator: Ferrari, A.; U., /Uppsala; Nosochkov, Y. & /SLAC
Partner: UNT Libraries Government Documents Department

Pair Creation at Large Inherent Angles

Description: In the next-generation linear colliders, the low-energy e{sup +}e{sup -} pairs created during the collision of high-energy e{sup +}e{sup -} beams would cause potential deleterious background problems to the detectors. At low collider energies, the pairs are made essentially by the incoherent process, where the pair is created by the interaction of beamstrahlung photons on the individual particles in the oncoming beam. This problem was first identified by Zolotarev, et al[1]. At energies where the beamstrahlung parameter {Upsilon} lies approximately in the range 0.6 {approx}< {Upsilon} {approx}< 100, pair creation from the beamstrahlung photons is dominated by a coherent process, first noted by Chen[2]. The seriousness of this pair creation problem lies in the transverse momenta that the pair particles carry when leaving the interaction point (IP) with large angles. One source of transverse momentum is from the kick by the field of the oncoming beam which results in an outcoming angle {theta} {proportional_to} 1/{radical}x, where x is the fractional energy of the particle relative to the initial beam particle energy[2,3]. As was shown in Ref. 131, there in fact exists an energy threshold for the coherent pairs, where x{sub th} {approx}> 1/2{Upsilon}. Thus within a tolerable exiting angle, there exists an upper limit for {Upsilon} where all coherent pairs would leave the detector through the exhaust port[4]. A somewhat different analysis has been done by Schroeder[5]. In the next generation of linear colliders, as it occurs, the coherent pairs can be exponentially suppressed[2] by properly choosing the {Upsilon}({approx}< 0.6). When this is achieved, the incoherent pairs becomes dominant. Since the central issue is the transverse momentum for particles with large angles, we notice that there is another source for it. Namely, when the pair particles are created at low energies, the intrinsic angles of these pairs when produced may ...
Date: April 25, 2007
Creator: Chen, P.; Tauchi, T.; Schroeder, D.V. & /SLAC
Partner: UNT Libraries Government Documents Department

The Exclusive Investigation of Multiple Production in Rapidity Space

Description: Recently it has become clear that only an inclusive model is not enough to explain interaction mechanism in the high energy region. We have been analyzing about the multiple meson production by using accelerator data and have gotten the conclusion that the exclusive investigation of rapidity gives an important information about the interaction mechanism. The experiment aims to measure the rapidity of the charged particles excluSively for individual event and to investigate the correlation among the number of charged particles Nc, the rapidity density {rho}, the mean value {bar {eta}} and the dispersion {sigma} of a rapidity distribution for each event.
Date: January 1, 1985
Creator: Nanjo, H.; Noto, Y.; Ishikawa, K. & U., /Hirosaki
Partner: UNT Libraries Government Documents Department

Power Losses in the ILC 20-Mrad Extraction Line at 1-TeV

Description: The authors have performed a detailed study of the power losses in the post-collision extraction line of a TeV e{sup +}e{sup -} collider with a crossing angle of 20 mrad at the interaction point. Five cases were considered: four luminosity configurations for ILC and one for CLIC. For all of them, the strong beam-beam effects at the interaction point lead to an emittance growth for the outgoing beam, as well as to the production of beamstrahlung photons and e{sup +}e{sup -} coherent pairs. The power losses along the extraction line, which are due to energy deposition by a fraction of the disrupted beam, of the beamstrahlung photons and of the coherent pairs, were estimated in the case of ideal collisions, as well as with a vertical position or angular offset at the interaction point.
Date: July 2, 2007
Creator: Ferrari, Arnaud; U., /Uppsala; Nosochkov, Yuri & /SLAC
Partner: UNT Libraries Government Documents Department

Control and manipulation of electron beams

Description: The concepts of the advanced accelerators and light source rely on the production of bright electron beams. The rms areas of the beam phase space often need to be tailored to the specific applications. Furthermore, a new class of the forefront research calls for detailed specific distribution such as the particle density in the time coordinate. Several groups are tackling these various challenges and in this report we attempt to give a review of the state-of-the-art of the control and manipulation of the electron beams.
Date: September 1, 2008
Creator: Piot, Philippe & /NICADD, DeKalb /Northern Illinois U. /Fermilab
Partner: UNT Libraries Government Documents Department

Certification of Superconducting Solenoid-Based Focusing Lenses

Description: The first production focusing lens for the HINS beam line at Fermilab has been assembled into a cryostat and tested. A total of 5 devices will be tested before they are installed in the low energy section of the HINS beam line, which uses copper Crossbar-H (CH) style RF cavities. One of the tested CH-section lens assemblies includes a pair of weak orthogonal steering dipoles nested within a strong focusing solenoid, and has six vapor cooled power leads. The other device has only the strong focusing solenoid, and utilizes a single pair of HTS power leads. The production test program is designed to measure the thermal performance of the cryostat, minimum cooling requirements for the HTS leads, quench performance of all superconducting components, and precise determination of the magnetic axis and field angles. Results and future plans for the first production device tests are presented.
Date: July 29, 2010
Creator: DiMarco, E.Joseph; Hemmati, Ali M.; Orris, Darryl F.; Page, Thomas M.; Rabehl, Roger H.; Tartaglia, Michael A. et al.
Partner: UNT Libraries Government Documents Department

A Study of the Average Multiplicity and Multiplicity Distributions in Hadron-Nucleus Collisions at High Energies

Description: In a simple counter experiment requiring about 40 hours of data taking time we propose to study the detailed shape of the multiplicity distribution for larger values of n and the average charged particle multiplicity in hadron-nucleus collisions at 100 and 200 Gev. The results of the experiment should be a valuable input for ccmparison with theoretical models, in particular they should provide a sensitive test ot whether multipartlcle production in hadron-nucleon collisions proceeds through a one or two step process.
Date: June 1, 1972
Creator: Busza, W.; Friedman, J.I.; Kendall, H.W.; Rosenson, L. & /MIT
Partner: UNT Libraries Government Documents Department

Transverse-to-longitudinal phase space exchange: a versatile tool for shaping the current and energy profiles of relativistic electron bunches

Description: Over the recent years, the emergence of accelerator beamlines capable of exchanging the phase space coordinates between two degrees of freedom have opened the path toward the precise control of phase space distribution and in particular to the production of relativistic electron beams with shaped current profiles. After briefly reviewing the technique, we present its application to produce a train of sub-picosecond microbunches and report on its experimental implementation at the Fermilab's A0 photoinjector facility.
Date: August 1, 2010
Creator: Piot, P.; /NICADD, DeKalb /Fermilab; Sun, Y.-E.; /Fermilab; Johnson, A.S.; Lumpkin, A.H. et al.
Partner: UNT Libraries Government Documents Department

Summary I - accelerator ion sources, fundamentals and diagnostics

Description: The 11th International Symposium on the Production and Neutralization of Negative Ions and Beams was held in Santa Fe, New Mexico on September 12-15, 2006 and was hosted by Los Alamos National Laboratory. This summary covers the first three oral sessions of the symposium.
Date: October 1, 2006
Creator: Moehs, Douglas P.
Partner: UNT Libraries Government Documents Department

Improvement in the laser system for the A0 TTF photoinjector

Description: The production of high charge and high brightness electron beams places increasingly challenging demands on the drive laser used at the A0 photoinjector in the Fermilab. The IR and UV laser pulse lengths need to be optimized for such purpose. We have experimentally investigated two different ways to change the UV laser pulse length on the cathode; either by changing the bandwidth of the oscillator or by changing the distance between two compression gratings, the UV laser pulse length can be varied in the range of 3ps to 30ps. Also the strong correlation between the UV laser energy and the IR laser pulse length has been studied, and the result is applied to achieve the UV laser energy of 18 {micro}J/pulse.
Date: March 1, 2003
Creator: Yang, Xi
Partner: UNT Libraries Government Documents Department

Planned Use of Pulsed Crab Cavities for Short X-Ray Pulse Generation at the Advanced Photon Source

Description: Recently, we have explored application to the Advanced Photon Source (APS) of Zholents'[1] crab cavity scheme for production of short x-ray pulses. We assumed use of superconducting (SC) cavities in order to have a continuous stream of crabbed bunches and flexibility of operating modes. The challenges of the SC approach are related to the size, cost, and development time of the cavities and associated systems. A good case can be made [2] for a pulsed system using room-temperature cavities. APS has elected to pursue such a system in the near term, with the SC-based system planned for a later date. This paper describes the motivation for the pulsed system and gives an overview of the planned implementation and issues. Among these are overall configuration options and constraints, cavity design options, frequency choice, cavity design challenges, tolerances, instabilities, and diagnostics plans.
Date: November 6, 2007
Creator: Borland, Michael; Carwardine, J.; Chae, Y.; Emery, L.; Den Hartog, Patric; Harkay, K.C. et al.
Partner: UNT Libraries Government Documents Department

Analysis of Positron Collection in the Linear Collider

Description: In the Linear Collider, the positron capture system includes a positron production target, an adiabatic matching device (AMD), and a linac to accelerate positrons up to the injection energy of the positron damping ring. Efficiency of the positron collector is defined by the number of positrons accepted into the damping ring. Analysis of the positron collection system is performed using a conventional scheme, where positrons are produced by a high-energy electron beam hitting the high-Z target. The collection system has been optimized to insure high positron capture into the 6-dimensional acceptance of the damping ring. Various parameters affecting the positron capture are analyzed.
Date: May 27, 2005
Creator: Batygin, Yuri K.af SLAC
Partner: UNT Libraries Government Documents Department

The Wakefield Effects of Pulsed Crab Cavities at the Advanced Photon Source for Short-X-ray Pulse Generation

Description: In recent years we have explored the application to the Advanced Photon Source (APS) of Zholents' crab-cavity based scheme for production of short x-ray pulses. As a near-term project, the APS has elected to pursue a pulsed system using room-temperature cavities. The cavity design has been optimized to heavily damp parasitic modes while maintaining large shunt impedance for the deflecting dipole mode. We evaluated a system consisting of three crab cavities as an impedance source and determined their effect on the single- and multi-bunch instabilities. In the single-bunch instability we used the APS impedance model as the reference system in order to predict the overall performance of the ring when the crab cavities are installed in the future. For multi-bunch instabilities we used a realistic fill pattern, including hybrid-fill, and tracked multiple bunches where each bunch was treated as soft in distribution.
Date: November 7, 2007
Creator: Chae, Y.-C.; Waldschmidt, G.; /Argonne; Dolgashev, V. & /SLAC
Partner: UNT Libraries Government Documents Department

A Laser-Driven Linear Collider: Sample Machine Parameters and Configuration

Description: We present a design concept for an e{sup +}e{sup -} linear collider based on laser-driven dielectric accelerator structures, and discuss technical issues that must be addressed to realize such a concept. With a pulse structure that is quasi-CW, dielectric laser accelerators potentially offer reduced beamstrahlung and pair production, reduced event pileup, and much cleaner environment for high energy physics and. For multi-TeV colliders, these advantages become significant.
Date: May 20, 2011
Creator: Colby, E.R.; England, R.J.; Noble, R.J. & /SLAC
Partner: UNT Libraries Government Documents Department

Photoinjectors R&D for future light sources & linear colliders

Description: Linac-driven light sources and proposed linear colliders require high brightness electron beams. In addition to the small emittances and high peak currents, linear colliders also require spin-polarization and possibly the generation of asymmetric beam in the two transverse degrees of freedom. Other applications (e.g., high-average-power free-electron lasers) call for high duty cycle and/or (e.g., electron cooling) angular-momentum-dominated electron beams. We review ongoing R&D programs aiming at the production of electron beams satisfying these various requirements. We especially discuss R&D on photoemission electron sources (with focus on radiofrequency guns) along with the possible use of emittance-manipulation techniques.
Date: August 1, 2006
Creator: Piot, P.
Partner: UNT Libraries Government Documents Department

Mechanical design of ceramic beam tube braze joints for NOvA kicker magnets

Description: The NO?A Experiment will construct a detector optimized for electron neutrino detection in the existing NuMI neutrino beam. The NuMI beam line is capable of operating at 400 kW of primary beam power and the upgrade will allow up to 700 kW. Ceramic beam tubes are utilized in numerous kicker magnets in different accelerator rings at Fermi National Accelerator Laboratory. Kovar flanges are brazed onto each beam tube end, since kovar and high alumina ceramic have similar expansion curves. The tube, kovar flange, end piece, and braze foil alloy brazing material are stacked in the furnace and then brazed. The most challenging aspect of fabricating kicker magnets in recent years have been making hermetic vacuum seals on the braze joints between the ceramic and flange. Numerous process variables can influence the robustness of conventional metal/ceramic brazing processes. The ceramic-filler metal interface is normally the weak layer when failure does not occur within the ceramic. Differences between active brazing filler metal and the moly-manganese process will be discussed along with the applicable results of these techniques used for Fermilab production kicker tubes.
Date: May 1, 2010
Creator: Ader, C.R.; Reilly, R.E.; Wilson, J.H. & /Fermilab
Partner: UNT Libraries Government Documents Department

Run II luminosity progress

Description: The Fermilab Tevatron Collider Run II program continues at the energy and luminosity frontier of high energy particle physics. To the collider experiments CDF and D0, over 3 fb{sup -1} of integrated luminosity has been delivered to each. Upgrades and improvements in the Antiproton Source of the production and collection of antiprotons have led to increased number of particles stored in the Recycler. Electron cooling and associated improvements have help make a brighter antiproton beam at collisions. Tevatron improvements to handle the increased number of particles and the beam lifetimes have resulted in an increase in luminosity.
Date: June 1, 2007
Creator: Gollwitzer, K.
Partner: UNT Libraries Government Documents Department