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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

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

Experiments on the beam--beam effect in e/sup +/e/sup -/ storage rings

Description: The maximum luminosity in a positron electron storage ring is fundamentally limited by the beam--beam effect. This is the perturbing effect of the electromagnetic field of one beam on the trajectory of every single particle of the other beam. The electromagnetic field of a charged particle beam is highly nonlinear. At a large distance from the beam center the field falls off like the inverse of the distance. Right in the center of the beam where we have a more or less uniform density distribution over a limited region the field rises linear with the distance from the center. So the field rises from the center of the beam, saturates at some distance and going further out falls off again as 1/r. The amplitude of the field depends on the charge density as well as the aspect ratio of the beam. If the electromagnetic field of one beam gets too large, particles of the other beam get lost which leads to a reduced beam lifetime. This effect has been observed in all electron--positron or electron--electron storage rings built so far and is considered the fundamental limit of the performance of electron--positron storage rings. Over the years many measurements have been performed at various laboratories to find the maximum permissible perturbation and the parametric dependence of that perturbation. In this paper, new measurements performed at SPEAR are presented and compared with measurements from ACO, ADONE, and VEEP-2M. Results from other storage rings have been ignored because they either show lower permissible perturbations or because of insufficient published data.
Date: May 1, 1979
Creator: Wiedemann, H.
Partner: UNT Libraries Government Documents Department

Electron beam spectrum monitor using synchrotron light

Description: This instrument shows the positions, widths, and shapes of momentum spectra of SLAC beams. It uses synchrotron light produced when the beam is deflected by a magnet. Some of the light is focused on the face of an image splitter consisting of acrylic light pipes. The light pipes illuminate twelve photomultiplier tubes. Pulses from the PM tubes are integrated, multiplexed, and displayed on an oscilloscope. The resolution of the instrument is usually better than 0.2%. It has some advantages over the secondary emitter foil spectrum monitors (SEM's) currently in use at SLAC. It need never be put out of service to avoid disturbing the beam. It is as sensitive as the most sensitive SLAC SEM. (Its performance has been optimized for high-current beams; it can easily be made much more sensitive.) It provides information on a pulse-to-pulse basis and, with better cables, could indicate electron beam pulse shapes.
Date: March 1, 1979
Creator: Reagan, D. & Hostetler, T.E.
Partner: UNT Libraries Government Documents Department

Further measurements of parity non-conservation in inelastic electron scattering. [16. 2 to 22. 2 GeV]

Description: Measurements of the y-dependence of the parity nonconserving asymmetries for inelastic electron scattering from deuterium. The measurements cover a range of y values from 0.15 to 0.36 and show only a small y-dependence. The results are in good agreement with the Weinberg-Salam model for sin/sup 2/theta/sub W/ = 0.224 +- 0.020. 20 references.
Date: January 1, 1979
Creator: Prescott, C.Y.
Partner: UNT Libraries Government Documents Department

Hadron production by e/sup +/e/sup -/ annihilation at center-of-mass energies between 2. 6 and 7. 8 GeV

Description: Results are presented on multihadron production by e/sup +/e/sup -/ annihilation from the Mark I and Mark II detectors at SPEAR. Other than the narrow resonances psi (3095) and psi' (3684), the total hadronic cross section varies between 36.5 and 6.4 nb over the center-of-mass energy range 2.6 to 7.8 GeV with complicated structure near 4.1 GeV not completely resolved by these measurements. Evidence for scaling of inclusive momentum distributions of hadrons is presented.
Date: October 1, 1979
Creator: Siegrist, J.L.
Partner: UNT Libraries Government Documents Department

Decays of the psi'(3684) to other charmonium states

Description: An experimental study of the decays of the psi'(3684) to other charmonium states is reported. The decays of 10/sup 6/ psi'(3684)'s were observed with the SLAC-LBL Mark II detector at the e/sup +/e/sup -/ storage ring SPEAR. Branching ratios have been measured for psi'(3684) decays to ..gamma.. chi where the chi decays to ..gamma.. psi(3095) or to hadrons. An upper limit of 0.13% is set on the branching ratio for psi' ..-->.. ..gamma.. chi(3455) ..-->.. ..gamma gamma.. psi(3095); this is a factor of 6 less than the branching ratio measured by a previous less sensitive experiment. The decay psi' ..-->.. ..gamma.. eta/sub c/, eta/sub c/ ..-->.. hadrons is investigated. The decay psi' ..-->.. ..pi../sup 0/psi, which violates isospin conservation, is observed with a branching ratio of (0.15+-0.06)%.
Date: October 1, 1979
Creator: Himel, T.M.
Partner: UNT Libraries Government Documents Department

Elements of quantum chromodynamics

Description: The subject of quantum chromodynamics is discussed at length. The introduction motivates the exposition and points out the analogies between QCD and QED. Then, after some assumptions about the nature of QCD, a description is given of what the solution of the theory should look like for three stages of complexity: pure QCD with no fermions or other sources, introduction of superheavy quarks, introduction of the light quarks (u, d, s) with vacuum polarization and pair creation. Next, canonical quantization of QCD by use of a Hamiltonian formulation (in A/sub 0/ = 0 gauge) is considered; gauge ambiguities, theta vacua, instantons, etc., are encountered. Then the properties of the three stages noted above are discussed in much greater detail. These follow descriptions of the confinement problem and various approaches to it, as well as of more radical alternatives to QCD, such as the string model or the Pati-Salam program. Included in the summary is an assessment of the current situation. 101 references, 23 figures, 2 tables. (RWR)
Date: January 1, 1979
Creator: Bjorken, J.D.
Partner: UNT Libraries Government Documents Department

Aspects of computer control from the human engineering standpoint

Description: A Computer Control System includes data acquisition, information display and output control signals. In order to design such a system effectively we must first determine the required operational mode: automatic control (closed loop), computer assisted (open loop), or hybrid control. The choice of operating mode will depend on the nature of the plant, the complexity of the operation, the funds available, and the technical expertise of the operating staff, among many other factors. Once the mode has been selected, consideration must be given to the method (man/machine interface) by which the operator interacts with this system. The human engineering factors are of prime importance to achieving high operating efficiency and very careful attention must be given to this aspect of the work, if full operator acceptance is to be achieved. This paper will discuss these topics and will draw on experience gained in setting up the computer control system in Main Control Center for Stanford University's Accelerator Center (a high energy physics research facility). (In this complex system both open and closed loop computer controls are used, as well as large numbers of manual functions.)
Date: March 1, 1979
Creator: Huang, T.V.
Partner: UNT Libraries Government Documents Department