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Tolerable Beam Loss at High-Intensity Machines

Description: Tolerable beam losses are estimated for high-intensity ring accelerators with proton energy of 3 to 16 GeV. Dependence on beam energy, lattice and magnet geometry is studied via full Monte Carlo MARS14 simulations in lattice elements, shielding, tunnel and surrounding dirt with realistic geometry, materials and magnetic fields.
Date: August 28, 2000
Creator: Oleg E. Krivosheev, Nikolai V. Mokhov
Partner: UNT Libraries Government Documents Department

Fixed field circular accelerator designs

Description: The rapid rate and cycle time required to efficiently accelerate muons precludes conventional circular accelerators. Recirculating linacs provide one option, but the separate return arcs per acceleration pass may prove costly. Recent work on muon acceleration schemes has concentrated on designing fixed-field circular accelerators whose strong superconducting fields can sustain a factor of 4 increase in energy from injection to extraction. A 4 to 16 GeV fixed-field circular accelerator has been designed which allows large orbit excursions and the tune to vary as a function of momentum. Acceleration is .6 GeV per turn so the entire cycle consists of only 20 turns. In addition, a 16 to 64 GeV fixed-field circular accelerator has been designed which is more in keeping with the traditional Fixed Field Alternating Gradient machines. In this work the two machine designs are described.
Date: January 6, 2000
Creator: Johnstone, C.; Wan, W. & Garren, A.
Partner: UNT Libraries Government Documents Department

Workshop on the AGS fixed-target research program

Description: The summarized results of a two day workshop to determine experiment programs for the Brookhaven AGS during the construction period of the ISABELLE storage rings and after are presented. Topics covered include: experiments with low-energy beams; experiments with higher energy beams; neutrino physics; and polarized protons. (GHT)
Date: January 1, 1978
Creator: Ahrens, L.; Schewe, P.; Wanderer, P. & Weisberg, H.
Partner: UNT Libraries Government Documents Department

Overview of colliding beam facilities

Description: A review is presented of the colliding beam facilities in existence today. The major high energy physics facilities around the world are described, and a view is presented of the beam collisions in which the instruments used to make the beams collide and those used to detect the products of particle interactions in the beam overlap region are described. (GHT)
Date: January 1, 1979
Creator: Herrera, J.C. & Month, M.
Partner: UNT Libraries Government Documents Department

Measurement of the longitudinal coupling impedance in the Brookhaven AGS

Description: The imaginary part of the longitudinal coupling impedance has been measured as a function of energy from 5 to approx. 28 GeV. This impedance is proportional to ..delta..f = (f/sub q/--2f/sub d/) where f/sub d/ is the coherent dipole frequency and f/sub q/ the coherent quadrupole frequency. These frequencies are obtained by stimulating coupled bunch oscillations. If the dominant impedance is due to inductive wall plus space charge effects, then one has (Z/n) = j(..cap omega../sub 0/L--g/sub 0/Z/sub 0//2BETA..gamma.../sup 2/)/sup 1/ where L is the inductance per turn and ..cap omega../sub 0/ = 2..pi..f/sub 0/ the particle rotation frequency. The expression (Z/n) = 4j..delta..f..pi../sup 2/hV/sub 0/cos phi/sub s/B/sup 3//3I/sub 0/f/sub d/ can be used to find the impedance if the synchrotron phase space distribution is proportional to (1--r/sup 2/)/sub 1/2/. I/sub 0/ is the current per bunch, B = f/sub 0/ x tau/sub 0/ the bunch length and V/sub 0/ is the external voltage. For a distribution given by (1--r/sup 2/) the right hand side should be multiplied by 27/4..pi../sup 2/. If the latter is assumed, an inductive impedance of 20.4 ..cap omega.. is obtained with a null at approx. = 6 Gev (..gamma../sub tr/ = 8.5) for a transverse emittance of 22 ..pi mu.. rad-m. At 5 GeV the reactance is negative but larger than the simple relation assumed for (Z/n) would predict. If the bunches are parabolic, then the inductive impedance would be 29.7 ..cap omega.. with a null again at 6.6 GeV but only for an emittance of 2.5 ..mu..rad-m. Again the 5 GeV reactance is much too large. The significance of these results is discussed.
Date: January 1, 1979
Creator: Pedersen, F. & Raka, E.C.
Partner: UNT Libraries Government Documents Department

Overview of CEBAF operations and SRF-related activities at Jefferson Lab

Description: The Jefferson Lab nuclear physics accelerator, CEBAF, continues to reliably deliver polarized CW electron beams with energy in the range of 1--5.5 GeV. The 330 installed 1,500 MHz SRF cavity systems perform solidly, contributing a small fraction of the machine downtime. The 5-pass energy capability has been pushed to near 6 GeV by application of in situ helium processing to almost all of the cavities. New operational tools have been developed and deployed which allow the operators to quickly reconfigure the linacs for optimal performance under various energy and beamloading conditions. Plans are being developed for upgrading CEBAF to 12 GeV. This requires a new cryomodule design and use of 5.5 recirculations for the top energy. Subsystem development is underway on a 7-cell cavity, new zero-backlash tuner, improved magnetic shielding, and an arc-free waveguide rf feed, as well as a new cryomodule mechanical system. Significant facility changes have been made in preparation for this work. A new rf control system will also be required. In addition to the successful nuclear physics program, the JLab FEL produced a world-record 1.7 kW CW in the infrared. An upgrade program is ready to begin. Significant efforts have also been directed in support of APT and RIA, as well as collaborations related to cavity fabrication and processing techniques.
Date: November 1, 1999
Creator: Reece, Charlie
Partner: UNT Libraries Government Documents Department

The ring imaging Cerenkov detector for the BRAHMS experiment at RHIC

Description: A ring-imaging Cerenkov counter, to be read out by four 100-channel PMT`S, is a key element of the BRAHMS Experiment. We report here the most recent results obtained with a prototype tested at the BNL AGS using several radiator gases, including the heavy fluorocarbon C{sub 4}F{sub 10}. Ring radii were measured for different particles {pi}{sup {minus}}, {mu}{sup {minus}}, e{sup {minus}} for momenta ranging from 2 to 12 GeV/c employing pure C{sub 4}F{sub 10} as radiator.
Date: August 1, 1995
Creator: Debbe, R.; Gushue, S.; Moskowitz, B.; Olness, J. & Videbaek, F.
Partner: UNT Libraries Government Documents Department

Beam-beam limit simulation of SPEAR I

Description: We discuss here an attempt to simulate the beam-beam limit effect in the SPEAR I 1.5 GeV storage ring located at SLAC. A summary discussion is given of the models used and the results obtained. Remarks are made concerning the difficulties encountered in this simulation problem.
Date: August 1, 1979
Creator: Close, E.
Partner: UNT Libraries Government Documents Department

Conceptual design of a 4-GeV hexagonal microtron

Description: This paper describes a higher-order variant of the microtron which offers an attractive option for furnishing cw electron beams at 4 GeV. The accelerator is a six-sided microtron consisting of three dispersive straight sections and three dispersion-free straight sections of constant length where three linacs are located.
Date: January 1, 1982
Creator: Khoe, T.K.
Partner: UNT Libraries Government Documents Department

Pulsars as the Source of the WMAP Haze

Description: The WMAP haze is an excess in the 22 to 93 GHz frequency bands of WMAP extending about 10 degrees from the galactic center. We show that electron-positron pairs injected into the interstellar medium by the galactic population of pulsars with energies in the 1 to 100 GeV range can explain the WMAP haze. The same spectrum of high energy electron-positron pairs from pulsars, which gives rise to the haze, can also explain the observed excesses in AMS, HEAT and PAMELA.
Date: May 1, 2009
Creator: Kaplinghat, Manoj; /UC, Irvine; Phalen, Daniel J.; U., /Michigan; Zurek, Kathryn M. & U., /Fermilab /Michigan
Partner: UNT Libraries Government Documents Department

Early Measurement of 200 GeV PP Large Angle Elastic Scattering

Description: The proton-proton angular distribution would be determined in the region 4<-t<20 Gev{sup 2} at 200 Gev/c and 10<-t<20 Gev{sup 2} at 400 Gev/c by measuring both scattered protons after magnetic analysis with proportional wire chambers in Proton West. Cross sections as low as {approx}0{sup -38} cm{sup 2} /Gev{sup 2} could be measured with an average beam intensity {approx} 10{double_prime} protons/sec.
Date: January 1, 1972
Creator: Orear, J.; Klems, J.; U., /Cornell; Ryan, D.; Stairs, D.; U., /McGill 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

A measurement of the b quark fragmentation function at {radical}Q{sup 2} = 45.6 GeV

Description: Presented here is a measurement of the b quark fragmentation function D{sub b}(X), taken from a sample of 504 semi-leptonic B decays which were selected from the 150,000 Z{sup 0} decays collected between 1993 and 1995 at the SLD at SLAC. The energy of each tagged B hadron is reconstructed using missing jet energy, based on the information from the lepton and a partially-reconstructed charm-decay vertex. Account is taken of the effect of primary orbitally excited mesons (B**s). An iterative unfolding procedure is used which serves to effectively extract the true fragmentation function from the reconstructed B energy spectrum. The final result is shown to be compatible with many theoretical models. A comparison is made with other b fragmentation function measurements at 45.6 GeV, and this measurement is shown to be consistent with those results. The average scaled energy is found to be (x{sub E}) = 0.697{+-} 0.017(stat) {+-} 0.034(sys).
Date: June 1, 1996
Creator: Church, E.D.
Partner: UNT Libraries Government Documents Department