80 Matching Results

Search Results

Advanced search parameters have been applied.

Exclusive processes and the exclusive-inclusive connection in quantum chromodynamics

Description: An outline of a new analysis of exclusive processes and quantum chromodynamics is presented. The main elements of this work involve a consistent Fock space decomposition of the hadronic wave function, plus evolution equations for wave functions which allow an exact evaluation of hadronic matrix elements in the asymptotic short distance limit. 77 references. (JFP)
Date: March 1, 1979
Creator: Brodsky, S.J. & Lepage, G.P.
Partner: UNT Libraries Government Documents Department

Large momentum transfer electron scattering from few-nucleon systems

Description: A review is given of the experimental results from a series of measurements at SLAC of large momentum transfer (Q/sup 2/ > 20 fm/sup -2/) electron scattering at forward angles from nuclei with A less than or equal to 4. Theoretical interpretations of these data in terms of traditional nuclear physics models and in terms of quark constituent models are described. Some physics questions for future experiments are explored, and a preview of possible future measurements of magnetic structure functions of light nuclei at large Q/sup 2/ is given.
Date: August 1, 1979
Creator: Arnold, R.G.
Partner: UNT Libraries Government Documents Department

Meson radiative decays. [Review, rates]

Description: The status of decays of the kind V ..-->.. P..gamma.. and P ..-->.. V..gamma..viewed with special emphasis on the work done by the authors in this field. The low experimental value of GAMMA(rho ..-->.. ..pi gamma..) remains the outstanding problem. The lastest preliminary numbers from a Fermi Laboratory experiment go in the right direction but not far enough. 15 references.
Date: April 1, 1979
Creator: Edwards, B.J. & Kamal, A.N.
Partner: UNT Libraries Government Documents Department

Survey of beam-beam limitations

Description: The effect of beam-beam interaction is known to limit the luminosity of electron-positron storage rings and will, no doubt, limit the proton-antiproton collision scheme for the SPS. While theorists are struggling to explain this phenomenon it is more instructive to list their failures than their rather limited successes, in the hope that experiments may emerge which will direct their endeavors. The search for a description of a nonlinear system as it approaches the limit in which ordered motion breaks down, is the nub of the problem. It has engaged many fine mathematical intellects for decades and will no doubt continue to do so long after ISABELLE, the p antip and LEP are past achievements. Empirical scaling laws are emerging which relate electron machines to each other but their extrapolation to proton machines remain a very speculative exercise. Experimental data on proton limits is confined to one machine, the ISR, which does not normally suffer the beam-beam effect and where it must be artificially induced or simulated. This machine is also very different in important ways from the p antip collider. The gloomy picture which has emerged recently is that the fixed limits which were conventionally assumed for proton and electron machines can only be said to be valid for the machines which engendered them - the best guess that could be made at the time. They are very difficult to extrapolate to other sets of parameters.
Date: January 1, 1979
Creator: Courant, E; Cornacchia, M; Donald, M M.R.; Evans, L R; Tazzari, S & Wilson, E J.N.
Partner: UNT Libraries Government Documents Department

Results on two-photon interactions from Mark II at SPEAR

Description: Preliminary results on two-photon interactions from the SLAC-LBL Mark II magnetic detector at SPEAR are presented. The cross section for eta' production by the reaction e/sup +/e/sup -/ ..-->.. e/sup +/e/sup -/ eta' has been measured over the beam energy range from 2 to 4 GeV. The radiative width GAMMA/sub ..gamma gamma../(eta') has been determined to be 5.8 +- 1.1 keV (+- 20% systematic uncertainty). Upper limits on the radiative widths of the f(1270), and A/sub 2/(1310) and f'(1515) mesons have been determined.
Date: October 1, 1979
Creator: Abrams, G.S.; Alam, M.S. & Blocker, C.A.
Partner: UNT Libraries Government Documents Department

Proposed orbit and vertical dispersion correction system for PEP

Description: The scheme for minimization of the rms orbit errors in ISR and SPEAR will be used to correct the closed orbit errors in PEP. The effectiveness of this scheme has been studied for some alignment and field errors in the PEP magnets and position monitors. It has been found for orbit correction system in PEP consisting of 48 correctors and 96 monitors, both horizontal and vertical orbits can be kept below 0.5 mm rms values even allowing for a position monitor alignment error of 0.5 mm rms. This method of correction has also been found to be usable to reduce the rms value of the vertical dispersion without appreciably affecting the corrected orbits. The result of this study is presented.
Date: February 1, 1979
Creator: Close, E.; Cornacchia, M.; King, A. & Lee, M.J.
Partner: UNT Libraries Government Documents Department

Results from the Mark II dectetor at SPEAR: SLAC-LBL Mark II collaboration

Description: Some recent results are presented from the Mark II detector at SPEAR: observation of some new D meson decay modes, including the Cabibbo suppressed K/sup -/K/sup +/ and ..pi../sup -/..pi../sup +/ modes, measurements of the rho ..nu.. and ..pi nu.. decays of the tau, and some new data on psi decays. 17 references.
Date: June 1, 1979
Creator: Abrams, G.S.; Alam, M.S. & Blocker, C.A.
Partner: UNT Libraries Government Documents Department

Personnel hazards from medical electron accelerator photoneutrons

Description: For medical accelerators, neutron penetration through the room entry door is the major personnel hazard. Most therapy accelerator rooms are designed with at least a rudimentary maze to avoid the use of massive doors. Often, however, the maze may be similar to those shown in scale outline drawings of some medical electron accelerator rooms where the authors have made neutron measurements outside the doors which were of different thicknesses and compositions. The results are tabulated. It should be noted that there can be significant dose equivalents (H) at the door when a maze is inadequate, and that all three components - fast neutron, thermal neutron, and neutron capture ..gamma.. rays - can be equally important.
Date: December 1, 1979
Creator: McCall, R.C.; Jenkins, T.M.; Shore, R.A. & LaRiviere, P.D.
Partner: UNT Libraries Government Documents Department

Large aperture contact ionized Cs/sup +1/ ion source for an induction linac

Description: A 500 KeV one-ampere Cs/sup +1/ ion beam has been generated by contact ionization with a 30 cm dia. iridium hot plate. Reproducibility of space charge limited ion current wave forms at repetition rates up to 1 Hz has been verified. The beam is characterized to be very bright and suitable as an ion source for the induction linac based heavy ion fusion scheme. The hot anode plate was found to be reliable and self-cleaning during the operation.
Date: March 1, 1979
Creator: Abbott, S.; Chupp, W.; Faltens, A.; Herrmannsfeldt, W.; Hoyer, E.; Keefe, D. et al.
Partner: UNT Libraries Government Documents Department

Some first results from the Mark II at SPEAR. [Branching ratio, cross sections]

Description: Preliminary results are given from the Mark II experiment at SPEAR on radiative decays of the psi' (3684) and on inclusive baryon production from 3.67 to 7.4 GeV center-of-mass energy. A 90% confidence level upper limit of 0.12% is given for BR(psi' ..-->.. ..gamma..eta'/sub c/(3455)) x BR(eta'/sub c/(3455 ..-->.. ..gamma..psi)). 10 references.
Date: June 1, 1979
Creator: Abrams, G.S.; Alam, M.S. & Blocker, C.A.
Partner: UNT Libraries Government Documents Department

Sensitivity of the PEP beam transport line to perturbations

Description: The sensitivity of a beam-transport line to various perturbations determines the extent to which one can simplify component design and relax tolerances. For the PEP injection lines, effects of various fabrication errors, magnet misalignments, and residual gas scattering were studied. Using the TURTLE ray-tracing program, it is found that magnetic-field errors corresponding to a relative sextupole strength in the dipoles of 0.5% and/or a relative sextupole or octupole strength in the quadrupoles of 5% are permissible. This allows relatively loose tolerances in magnet fabrication. Transverse misalignment of a quadrupole by a distance x causes the beam centroid to be displaced downstream by as much as 5x. This requires a quadrupole alignment accuracy of +- 0.5 mm or better. No compensation for the earth's field is necessary because an integral number of optical wavelengths and a short wavelength were used for the design. Analysis shows that beam broadening from multiple coulomb scattering is insignificant for pressures of less than 1/10 torr.
Date: March 1, 1979
Creator: Peterson, J.M. & Brown, K.L.
Partner: UNT Libraries Government Documents Department

Quark structure functions of mesons, fragmentation functions, higher-twist effects in QCD, deep inelastic scattering, and the Drell-Yan process. [Constituent binding in hadron wave function cross section azimuthal angular dependence]

Description: Inclusion of specific effects associated with constituent binding in hadronic wave functions is shown to lead to important nonscaling, nonfactorizing 1/Q/sup 2/ contributions to cross sections for semi-inclusive deep-inelastic scattering, the Drell-Yan process, and other hard scattering reactions. These 1/Q/sup 2/ higher-twist terms are predicted to be dominant in well defined kinematic regions such as large x and/or large z. They provide angular distributions typical of longitudinally polarized virtual photons and W's, including sin/sup 2/theta terms in meson induced Drell-Yan processes and in e/sup +/e/sup -/ ..-->.. ..pi..X, as well as unusual (1-y) terms in deep-inelastic scattering. Calculations are also presented of the quark structure functions of the pion q/sub ..pi../(x,Q/sup 2/) and for the quark to pion fragmentation function D/sub ..pi..(z,Q/sup 2/). Predictions are made for the azimuthal angle dependence of the cross sections for ..pi..N ..-->.. ..mu.. anti ..mu..X and lN ..-->.. l'..pi..X.
Date: July 1, 1979
Creator: Berger, E.L.
Partner: UNT Libraries Government Documents Department

Recent results from the Mark II detector at SPEAR

Description: Recent results rom the Mark II Detector at SPEAR are presented. These include measurements of the decays tau/sup -/ ..-->.. rho/sup -/..nu../sub tau/ and tau/sup -/ ..-->.. K*/sup -/(890)..nu../sub tau/, observation of direct photons at the psi, inclusive proton and ..lambda.. production and measurements of charmed baryon and charmed meson decays.
Date: November 1, 1979
Creator: Dorfan, Jonathan
Partner: UNT Libraries Government Documents Department

Pulsed rf systems for large storage rings

Description: In this note we consider the possibility that by using a pulsed rf system, perhaps a system which operates at a somewhat higher frequency, a substantial reduction can be made in the rf power requirement for the next generation of large storage rings. A large effort over a period of many years has been expended in the attempt to increase the shunt impedance of rf structures for cw systems. Without turning to superconductivity only modest gains in the shunt impedance remain to be made by further detailed adjustments in cell shape. On the other hand, very little effort has as yet gone into the optimization of structures for pulsed systems. The structure parameters to be quoted in this report do not therefore necessarily represent values close to those for an optimum design. It is expected that the system designs set out here can be improved upon with further experimental and theoretical work. 11 refs., 3 figs.
Date: February 1, 1979
Creator: Wilson, P.B.
Partner: UNT Libraries Government Documents Department

Weak-strong instability as a diffusion process

Description: The phenomenological analysis of the weak-strong instability for an electron storage ring is developed. The vertical size of the weak beam is found to depend on two machine parameters: {radical}{eta}, which is proportional to {Delta}Q, and b, which depends on the aspect ratio of the strong beam. The model also contains one fitting parameter. Experimental consequences of such dependence are discussed. 5 refs., 7 figs.
Date: February 1, 1979
Creator: Kheifets, S.A.
Partner: UNT Libraries Government Documents Department

Bench measurements of the loss impedance for PEP beam line components

Description: Bench measurements of the parasitic model loss parameter k, due to the interaction of a bunched beam with discontinuities in the vacuum pipe, are presented for many of the PEP beamline components. The measurements were made using the pulsed, coaxial transmission method of Sands and Rees. Full-scale machined and sheet metal models containing tapers, gaps, tanks (cavities) collimators, plates, electrodes and other irregular shapes were investigated. Accuracies, errors and modeling difficulties are pointed out. Loss curves and rules of thumb are discussed that should aid in the design of similar components. Also described is a moderately successful effort to de-Q some of the resonances in a particularly complicated chamber (separating plates) with a strip line coupling loop that is externally terminated at both ends.
Date: March 1, 1979
Creator: Weaver, J.N.; Wilson, P.B. & Styles, J.B.
Partner: UNT Libraries Government Documents Department

Angular distributions in the lepton pair production. [Review, Drell-Yan process, quantum chromodynamics, Compton diagrams, 200 GeV/c]

Description: The angular distributions of high mass lepton pairs are reviewed. It is argued that the detailed study of polar distributions provide the evidence for the substantial contributions to the Drell-Yan process from the higher order QCD effects. It is also pointed out that the first order QCD Compton diagrams predict nontrivial azimuthal dependence which could be measured experimentally. 13 references.
Date: October 1, 1979
Creator: Stroynowski, R.
Partner: UNT Libraries Government Documents Department

Bermuda Triangle: a subsystem of the 168/E interfacing scheme used by Group B at SLAC

Description: The Bermuda Triangle system is a method of interfacing several 168/E microprocessors to a central system for control of the processors and overlaying their memories. The system is a three-way interface with I/O ports to a large buffer memory, a PDP11 Unibus and a bus to the 168/E processors. Data may be transferred bidirectionally between any two ports. Two Bermuda Triangles are used, one for the program memory and one for the data memory. The program buffer memory stores the overlay programs for the 168/E, and the data buffer memory, the incoming raw data, the data portion of the overlays, and the outgoing processed events. This buffering is necessary since the memories of 168/E microprocessors are small compared to the main program and the amount of data being processed. The link to the computer facility is via a Unibus to IBM channel interface. A PDP11/04 controls the data flow. 7 figures, 4 tables. (RWR)
Date: December 1, 1979
Creator: Oxoby, G.J.; Levinson, L.J. & Trang, Q.H.
Partner: UNT Libraries Government Documents Department

Charmed meson production and decay properties at the psi(3770)

Description: A remeasurement of the resonance near E/sub cm/ = 3.77 GeV in the e/sup +/e/sup -/ annihilation is presented. The properties of the resonance are used to deduce branching fractions of charmed mesons into hadronic final states. Several previously unseen decay modes are reported. Decays into Cabibbo suppressed final states are observed. The inclusive properties of D meson decays are studied, including strangeness and charged particle multiplicity. The semileptonic branching fractions for D/sup 0/ and D/sup -+/ are measured, providing a determination of the relative lifetimes of these particles.
Date: May 1, 1979
Partner: UNT Libraries Government Documents Department

First results from Mark II at SPEAR

Description: First results from the SLAC-LBL Mark II magnetic detector at SPEAR are presented. The performance of the detector is discussed and preliminary results are given on inclusive baryon production R/sub p + anti p/, R/sub ..lambda.. + anti ..lambda../, on decay modes of the D mesons and on two-photon production of eta' mesons.
Date: May 1, 1979
Creator: Abrams, G.S.; Alam, M.S. & Blocker, C.A.
Partner: UNT Libraries Government Documents Department

High energy electron cooling to improve the luminosity and lifetime in colliding beam machines

Description: Electron cooling can be applied to improve the performance of high energy colliding beams of hadrons and e/sup -/p storage rings. Normal beam excitations such as multiple scattering, resonance growth, or beam--beam interaction can be controlled, leading to longer beam lifetimes, and in some situations to higher luminosities and larger tolerable tune shifts. The electrons, in a small storage ring, are cooled by radiation and heated by the hadron beam. An equilibrium is reached in which the hadron beam is cooled. The electron beam requires strong cooling by wigglers. A simple cooling experiment for the Fermilab synchrotron is described. Relativistic proton or antiproton beams in circular accelerators or storage rings can be damped by interactions with electrons (..gamma../sub p/ = ..gamma../sub c/) circulating in a storage ring. The proton or antiproton beam is damped and the electron beam is heated in the interaction. In order to reduce the blowup of the electron beam, synchrotron radiation in bending magnets or wiggler magnets and subsequent acceleration in an rf system is required, thus the electron beam is cooled.
Date: March 1, 1979
Creator: Cline, D.; Garren, A.; Herr, H.; Mills, F.E.; Rubbia, C.; Ruggiero, A. et al.
Partner: UNT Libraries Government Documents Department

Distribution function of the weak beam taking the interaction with the strong one into account

Description: Developing the idea of fast particle mixing due to a strong nonlinearity of the beam--beam interaction, the distribution function of the weak bunch in the phase space of vertical motion is found. The features of this distribution are discussed and compared to the Gaussian one.
Date: April 1, 1979
Creator: Kheifets, S.A.
Partner: UNT Libraries Government Documents Department

Electron trajectory program

Description: The SLAC Electron Trajectory Program is described and instructions and examples for users are given. The program is specifically written to compute trajectories of charged particles in electrostatic and magnetostatic focusing systems including the effects of space charge and self-magnetic fields. Starting options include Child's Law conditions on cathodes of various shapes. Either rectangular or cylindrically symmetric geometry may be used. Magntic fields may be specified using arbitrary configurations of coils, or the output of a magnet program such as Poisson or by an externally calculated array of the axial fields. The program is available in IBM FORTRAN but can be easily converted for use on other brands of hardware. The program is intended to be used with a plotter whose interface the user must provide.
Date: November 1, 1979
Creator: Herrmannsfeldt, W.B.
Partner: UNT Libraries Government Documents Department