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Designing SSC quadrupole supports to minimize the effects from vibrational noise

Description: G. Stupakov has shown theoretically that the emittance at the SSC should increase linearly with time and the seismic noise spectrum associated with quadrupole motion at the betatron frequency {approximately} 750--1500 Hz. While the motion is also affected by overtones of the knockout frequencies, the frequencies are so high that the seismic noise becomes vanishingly small. Feedback control would be required to control emittance growth for a power spectrum in excess of 10{sup {minus}12} microns{sup 2}/Hz, assuming unit transmission at the betatron knockout frequency through the quadrupole supports. At the 1991 Corpus Christi Workshop on Beam Dynamics, N. Dikanski predicted unacceptable emittance growths of minutes for the SSC collider in the absence of protective measures. In view of this prediction a workshop was convened in February of 1992 to discuss vibrational issues. At this workshop G. Fischer referred participants to an early study based on the then best compilation from Aki and Richards of seismic measurements. Aki and Richards showed ambient ground noise for a generic site many orders of magnitude lower than the INP measurements for the 750--1500 Hz range. Fischer referred to later extensive measurements in the US and USSR that had confirmed the Aki results and also showed that instrumental noise in the 750--1500 Hz region could dominate measurement precision. Later measurements made by the Russian group at the SSC site measure quiet noise spectra of Hz five orders of magnitude lower than the original values. Under noisy conditions measurements indicate that culturally induced vibrations might still lead to marginal emittance growth, assuming unit transmission in the relevant frequency range, and 100% efficient coupling of resonant modes to the beam. This is certainly an overestimate as relevant wavelengths are small compared with quadrupole dimensions.
Date: September 1, 1993
Creator: Ritson, D.
Partner: UNT Libraries Government Documents Department

HippoDraw and Hippoplotamus

Description: Hippo Draw is a result of research into finding better ways to visualize the kind of statistical data that is so common in high energy physics analyses. In these analyses, frequency distributions are visualized as histograms, contour plots, scatter plots, etc. Traditionally, one used a library of subroutines, called a histogram package, within one`s analysis programs to create and display such distributions. HippoDraw is a NeXTstep application for viewing statistical data. It has several unique features which make viewing data distributions highly interactive. It also incorporates simple drawing tools. HippoDraw is written in Objective-C and uses the Hippoplotamus library package which handles the n-tuples and displays. Hippoplotamus is written in ANSI C. 4 refs.
Date: February 1, 1992
Creator: Gravina, M. F.; Kunz, P. F.; Pavel, T. J. & Rensing, P. E.
Partner: UNT Libraries Government Documents Department

Measurements of gluon spin-sensitive quantities at the Z{sup 0} resonance

Description: Measurements have been made of the scaled jet energies (x{sub 1}, x{sub 2}, x{sub 3}) and the Ellis-Karliner angle (cos{theta}{sub EK}), which are sensitive to the spill of the gluon, in the 3-jet hadronic events from the e{sup +}e{sup {minus}} annihilation at the Z{sup 0} resonance. The experiment is performed with the SLD detector at the Stanford Linear Accelerator Center (SLAC). The data used in this analysis was collected during the 1992 physics run, which includes 10,252 hadronic Z{sup 0} events that have CDC information written out. Only charged tracks measured in the central drift chamber are used for the measurements of the above variables. The raw data are found to be in good agreement with the Monte Carlo simulations passing the same set of track and event selection cuts. A bin-to-bin correction is done for the distributions of x{sub 1}, x{sub 2}, x{sub 3}, and cos{theta}{sub EK} to account for the effects of hadronization, detector acceptance and resolution. The corrected data is compared to the parton level distributions of x{sub 1}, x{sub 2}, x{sub 3}, and cos{theta}{sub EK} simulated from the vector QCD model and the scalar gluon model respectively. The systematic errors, calculated for all the bins in these distributions, are obtained by comparing the results from different sets of track and event selection cuts, from different hadronization models and from different Monte Carlo programs. Good agreement is found between data and the vector QCD model. The scalar gluon model strongly disagrees with the data.
Date: October 1, 1993
Creator: Fan, C. G.
Partner: UNT Libraries Government Documents Department

First results from SLD with polarized electron beam at SLC

Description: The SLAC Linear Collider (SLC) has been modified to collide a longitudinally polarized electron beam with the unpolarized positron beam. We review the beginning of polarized beam running at the SLC, and report on the measurement of the left-right cross section asymmetry (A{sub LR}) made with a sample of 10,224 Z decays collected over the course of the 1992 run. The average beam polarization for this set of Z decays was 22.4 {plus_minus} 0.6%(syst.). A{sub LR} was measured to be 0.100 {plus_minus} 0.044(stat.) {plus_minus} 0.004(syst.). From this measurement, the weak mixing angle defined at the Z boson pole is determined to be sin{sup 2}{theta}{sup eff}{sub W} = 0.2378 {plus_minus} 0.0056 {plus_minus} 0.0005.
Date: December 1, 1992
Creator: Fero, M. J. & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

A measurement of the left-right cross section asymmetry in Z{sup 0} production with polarized e{sup +}e{sup {minus}} collisions

Description: The Stanford Linear Collider at SLAC is an e{sup +}e{sup {minus}} collider running at {radical}s {approx} M{sub Z} and has provided an electron beam with longitudinal polarization at the SLC interaction point. The 1992 polarized run data were taken with the SLD detector. The author presents here the measurement of the left-right cross section asymmetry (A{sub LR}) for the 1992 run. The polarized run began in May and ended in September of 1992 at a mean center-of-mass energy of 91.56 GeV. Tower hit information of the liquid argon calorimeter and endcap warm iron calorimeter pads were used for selecting hadronic Z{sup 0} or tau pair events. The SLD detector collected about 11,000 events during this run. The magnitude of the longitudinal polarization of the electron beam was continuously measured by a polarimeter based on Compton scattering, and was monitored by a polarimeter based on Moller scattering. The luminosity-weighted average longitudinal polarization during the 1992 run was measured as 22.4 {+-} 0.6 (syst.)%. From these data, the value of A{sub LR} has been measured to be 0.102 {+-} 0.044 (stat.) {+-} 0.003 (syst.), corresponding to an effective electroweak mixing angle (sin{sup 2}{theta}{sub w}{sup eff}) of 0.2375 {+-} 0.0056 (stat.) {+-} 0.0004 (syst.). The error is dominated by the statistical error. This value of sin{sup 2}{theta}{sub w}{sup eff} is in good agreement with existing measurements from other experiments. Studies of improvements in A{sub LR} event selection for future high-statistics runs are also discussed.
Date: December 1, 1993
Creator: Park, H.
Partner: UNT Libraries Government Documents Department

Polarized source performance in 1992 for SLC--SLD

Description: In its initial operation, the SLC Polarized Electron Source successfully met the SLC goals for 1992 for intensity and efficiency. However, the stability of the beam at the source was marginal, and the polarization was only {approximately}28%. The SLC goal to provide > 10,000 Z events for the SLD from polarized electrons was met.
Date: February 1, 1993
Creator: Schultz, D.; Alley, R.; Clendenin, J.; Frisch, J.; Garden, C.; Hoyt, E. et al.
Partner: UNT Libraries Government Documents Department

Tests of variable-band multilayers designed for investigating optimal signal-to-noise vs artifact signal ratios in Dual-Energy Digital Subtraction Angiography (DDSA) imaging systems

Description: In recent work, various design techniques were applied to investigate the feasibility of controlling the bandwidth and bandshape profiles of tungsten/boron-carbon (W/B{sub 4}C) and tungsten/silicon (W/Si) multilayers for optimizing their performance in synchrotron radiation based angiographical imaging systems at 33 keV. Varied parameters included alternative spacing geometries, material thickness ratios, and numbers of layer pairs. Planar optics with nominal design reflectivities of 30%--94% and bandwidths ranging from 0.6%--10% were designed at the Stanford Radiation Laboratory, fabricated by the Ovonic Synthetic Materials Company, and characterized on Beam Line 4-3 at the Stanford Synchrotron Radiation Laboratory, in this paper we report selected results of these tests and review the possible use of the multilayers for determining optimal signal to noise vs. artifact signal ratios in practical Dual-Energy Digital Subtraction Angiography systems.
Date: August 1, 1993
Creator: Boyers, D.; Ho, A.; Li, Q.; Piestrup, M.; Rice, M. & Tatchyn, R.
Partner: UNT Libraries Government Documents Department

Superconducting final focus for the SLAC Linear Collider

Description: Triplets composed of superconducting quadrupoles have been built and installed as the final focusing element for the high-energy positron and electron beams of the SLAC Linear Collider. Special features include independent alignment to 100-micron tolerance inside a common cryostat; non-magnetic materials to allow operation inside the detector`s solenoid field; a continuous-flow helium-only system using 50-meter-long flexible transfer lines; and complete operation of the system before installation. The mechanical design and cryogenic operation experience are presented.
Date: May 1, 1992
Creator: Ash, W. W.; Barrera, F.; Burgess, W.; Cook, K.; Cutler, H.; Ferrie, J. et al.
Partner: UNT Libraries Government Documents Department

Optimal routing of IP packets to multi-homed servers

Description: Multi-homing, or direct attachment to multiple networks, offers both performance and availability benefits for important servers on busy networks. Exploiting these benefits to their fullest requires a modicum of routing knowledge in the clients. Careful policy control must also be reflected in the routing used within the network to make best use of specialized and often scarce resources. While relatively straightforward in theory, this problem becomes much more difficult to solve in a real network containing often intractable implementations from a variety of vendors. This paper presents an analysis of the problem and proposes a useful solution for a typical campus network. Application of this solution at the Stanford Linear Accelerator Center is studied and the problems and pitfalls encountered are discussed, as are the workarounds used to make the system work in the real world.
Date: August 1, 1992
Creator: Swartz, K. L.
Partner: UNT Libraries Government Documents Department

The polarized electron gun for the SLC

Description: A new polarized electron gun for use on the SLC at SLAC has been built and tested. It is a diode gun with a laser driven GaAs photocathode. It is designed to provide short (2ns) pulses of 10 A at 160 kV at 120 Hz. The design features of the gun and results from a testing program on a new and dedicated beam line are presented. Early results from operation on the SLC will also be shown.
Date: March 1, 1992
Creator: Schultz, D. C.; Clendenin, J.; Frisch, J.; Hoyt, E.; Klaisner, L.; Woods, M. et al.
Partner: UNT Libraries Government Documents Department

Beamstrahlung spectra in next generation linear colliders. Revision

Description: For the next generation of linear colliders, the energy loss due to beamstrahlung during the collision of the e{sup +}e{sup {minus}} beams is expected to substantially influence the effective center-of-mass energy distribution of the colliding particles. In this paper, we first derive analytical formulae for the electron and photon energy spectra under multiple beamstrahlung processes, and for the e{sup +}e{sup {minus}} and {gamma}{gamma} differential luminosities. We then apply our formulation to various classes of 500 GeV e{sup +}e{sup {minus}} linear collider designs currently under study.
Date: April 1, 1992
Creator: Barklow, T.; Chen, P. & Kozanecki, W.
Partner: UNT Libraries Government Documents Department

Anomalous small angle x-ray scattering studies of amorphous metal-germanium alloys

Description: This dissertation addresses the issue of composition modulation in sputtered amorphous metal-germanium thin films with the aim of understanding the intermediate range structure of these films as a function of composition. The investigative tool used in this work is anomalous small-angle X-ray scattering (ASAXS). The primary focus of this investigation is the amorphous iron-germanium (a-Fe{sub x}Ge{sub 100-x}) system with particular emphasis on the semiconductor-rich regime. Brief excursions are made into the amorphous tungsten-germanium (a-W{sub x}Ge{sub 100-x}) and the amorphous molybdenum-germanium (a-Mo{sub x}Ge{sub 100-x}) systems. All three systems exhibit an amorphous structure over a broad composition range extending from pure amorphous germanium to approximately 70 atomic percent metal when prepared as sputtered films. Across this composition range the structures change from the open, covalently bonded, tetrahedral network of pure a-Ge to densely packed metals. The structural changes are accompanied by a semiconductor-metal transition in all three systems as well as a ferromagnetic transition in the a-Fe{sub x}Ge{sub 100-x} system and a superconducting transition in the a-Mo{sub x}Ge{sub 100-x} system. A long standing question, particularly in the a-Fe{sub x}Ge{sub 100-x} and the a-Mo{sub x}Ge{sub 100-x} systems, has been whether the structural changes (and therefore the accompanying electrical and magnetic transitions) are accomplished by homogeneous alloy formation or phase separation. The application of ASAXS to this problem proves unambiguously that fine scale composition modulations, as distinct from the simple density fluctuations that arise from cracks and voids, are present in the a-Fe{sub x}Ge{sub 100-x}, a-W{sub x}Ge{sub 100-x}, and a-Mo{sub x}Ge{sub 100-x} systems in the semiconductor-metal transition region. Furthermore, ASAXS shows that germanium is distributed uniformly throughout each sample in the x<25 regime of all three systems.
Date: December 1, 1993
Creator: Rice, M.
Partner: UNT Libraries Government Documents Department

Initial performance of the SLD Cherenkov Ring Imaging Detector system

Description: All of the major subsystems for the barrel Cherenkov Ring Imaging Detector (CRID) in the SLD at SLAC have now been commissioned. The CRID participated in the SLD engineering run of June--August 1991. In a cosmic ray test at the end of the run, Cherenkov rings were observed for the first time. Initial data from the CRID, including Cherenkov rings, studies of minimum ionizing particles, and data from the fiber optics calibration system are presented here.
Date: November 1, 1991
Creator: Abe, K.; Hasegawa, K.; Suekane, F.; Yuta, H.; Antilogus, P.; Aston, D. et al.
Partner: UNT Libraries Government Documents Department

A measurement of R{sub b} = {Gamma}(Z{sup 0} {yields} b{anti b})/{Gamma}(Z{sup 0} {yields} hadrons) at SLD

Description: A measurement of the ratio R{sub b} = {Gamma}(Z{sup 0} {yields} b{anti b})/{Gamma}(Z{sup 0} {yields} hadrons) is reported. This measurement is made using the CCD-based vertex detector of the SLD detector at the SLAC Linear Collider. Efficient tagging of the b{anti b} events is performed with an impact parameter technique that takes advantage of the small and stable interaction point of the SLC and all charged tracks in Z{sup 0} decays. In a sample of 27K Z{sup 0} events collected in 1992 & 1993, a value R{sub b} = 0.235 {+-} 0.006 {+-} 0.018 is obtained.
Date: December 1, 1993
Creator: Neal, H. A. Jr. & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

Quantized conic sections; quantum gravity

Description: Starting from free relativistic particles whose position and velocity can only be measured to a precision < {Delta}r{Delta}v > {equivalent_to} {plus_minus} k/2 meter{sup 2}sec{sup {minus}1} , we use the relativistic conservation laws to define the relative motion of the coordinate r = r{sub 1} {minus} r{sub 2} of two particles of mass m{sub 1}, m{sub 2} and relative velocity v = {beta}c = {sub (k{sub 1} + k{sub 2}})/ {sup (k{sub 1} {minus} k{sub 2}}) in terms of conic section equation v{sup 2} = {Gamma} [2/r {plus_minus} 1/a] where ``+`` corresponds to hyperbolic and ``{minus}`` to elliptical trajectories. Equation is quantized by expressing Kepler`s Second Law as conservation of angular niomentum per unit mass in units of k. Principal quantum number is n {equivalent_to} j + {1/2} with``square`` {sub T{sup 2}}/{sup A{sup 2}} = (n {minus}1)nk{sup 2} {equivalent_to} {ell}{sub {circle_dot}}({ell}{sub {circle_dot}} + 1)k{sup 2}. Here {ell}{sub {circle_dot}} = n {minus} 1 is the angular momentumquantum number for circular orbits. In a sense, we obtain ``spin`` from this quantization. Since {Gamma}/a cannot reach c{sup 2} without predicting either circular or asymptotic velocities equal to the limiting velocity for particulate motion, we can also quantize velocities in terms of the principle quantum number by defining {beta}{sub n}/{sup 2} = {sub c{sup 2}}/{sup v{sub n{sup 2}} = {sub n{sup 2}}/1({sub c{sup 2}}a/{Gamma}) = ({sub nN{Gamma}}/1){sup 2}. For the Z{sub 1}e,Z{sub 2}e of the same sign and {alpha} {triple_bond} e{sup 2}/m{sub e}{kappa}c, we find that {Gamma}/c{sup 2}a = Z{sub 1}Z{sub 2}{alpha}. The characteristic Coulomb parameter {eta}(n) {triple_bond} Z{sub 1}Z{sub 2}{alpha}/{beta}{sub n} = Z{sub 1}Z{sub 2}nN{sub {Gamma}} then specifies the penetration factor C{sup 2}({eta}) = 2{pi}{eta}/(e{sup 2{pi}{eta}} {minus} 1}). For unlike charges, with {eta} still taken as positive, C{sup 2}({minus}{eta}) = 2{pi}{eta}/(1 {minus} e{sup {minus}2{pi}{eta}}).
Date: March 15, 1993
Creator: Noyes, H. P.
Partner: UNT Libraries Government Documents Department

The beam-beam interaction in e{sup +}e{sup {minus}} storage rings

Description: This article is a personal perspective about the physics of the beam-beam interaction. This is an active area of research combining operational experience, experiments, computer models, and theory with the goal being to overcome the shortcomings above. This research hasn`t progressed sufficiently to quantitatively explain beam-beam limits, but there are qualitative explanations of many of the features of the beam-beam interaction and clear directions for future developments.
Date: March 1, 1993
Creator: Siemann, R. H.
Partner: UNT Libraries Government Documents Department

Accelerator simulation using computers

Description: Every accelerator or storage ring system consists of a charged particle beam propagating through a beam line. Although a number of computer programs exits that simulate the propagation of a beam in a given beam line, only a few provide the capabilities for designing, commissioning and operating the beam line. This paper shows how a ``multi-track`` simulation and analysis code can be used for these applications.
Date: January 1, 1992
Creator: Lee, M.; Zambre, Y. & Corbett, W.
Partner: UNT Libraries Government Documents Department

A three-gap klystron output cavity at X-band

Description: A high-power X-band klystron employing a double-gap output cavity has been operating at SLAC. Multi-gap output circuits have lower surface gradients at the interaction gaps than single-gap ones but are prone to self-oscillate due to negative loading and trapped higher-order modes. In the double-gap circuit design, considerable attention had been directed to deal with these stability problems. The performance of the present tube appears to be limited by gap breakdown and beam interception particularly at long pulses. A three-gap output cavity is currently under development to further reduce the gap surface gradient. Another new feature of the circuit is an enlarged downstream drift tube to improve on beam clearance. This paper discusses the considerations involved in designing a multi-gap output cavity and presents the cold test measurements on the three-gap circuit. The experimental data is compared with numerical results from the 3-D simulation code ARGUS.
Date: March 1, 1992
Creator: Ko, K.; Lee, T. G.; Tonegawa, S. & Kroll, N.
Partner: UNT Libraries Government Documents Department

Proceedings of the 1992 workshops on high-energy physics with colliding beams. Volume 3, Electroweak symmetry breaking at colliding-beam facilities

Description: This report contains viewgraphs on the following topics: Introduction to Electroweak Symmetry Breaking: Intermediate-Mass Higgs Bosons; Extended Higgs Sectors and Novel Searches; and Heavy Higgs Bosons and Strong WW Scattering.
Date: December 31, 1992
Creator: Rogers, J.
Partner: UNT Libraries Government Documents Department

A calorimetric measurement of the strong coupling constant in electron-positron annihilation at a center-of-mass energy of 91.6 GeV

Description: In this work, a measurement of the strong coupling constant {alpha}{sub s} in e{sup +}e{sup {minus}} annihilation at a center-of-mass energy of 91.6 GeV is presented. The measurement was performed with the SLD at the Stanford Linear Collider facility located at the Stanford Linear Accelerator Center in California. The procedure used consisted of measuring the rate of hard gluon radiation from the primary quarks in a sample of 9,878 hadronic events. After defining the asymptotic manifestation of partons as `jets`, various phenomenological models were used to correct for the hadronization process. A value for the QCD scale parameter {Lambda}{sub bar MS}, defined in the {sub bar MS} renormalization convention with 5 active quark flavors, was then obtained by a direct fit to O({alpha}{sub s}{sup 2}) calculations. The value of {alpha}{sub s} obtained was {alpha}{sub s}(M{sub z0}) = 0.122 {plus_minus} 0.004 {sub {minus}0.007} {sup +0.008} where the uncertainties are experimental (combined statistical and systematic) and theoretical (systematic) respectively. Equivalently, {Lambda}{sub bar MS} = 0.28 {sub {minus}0.10}{sup +0.16} GeV where the experimental and theoretical uncertainties have been combined.
Date: April 1, 1994
Creator: Martirena, S. G.
Partner: UNT Libraries Government Documents Department

JAZELLE users manual

Description: JAZELLE is a data management package, designed to provide facilities for data structure manipulation considerably more powerful than those provided by standard FORTRAN 77. Since JAZELLE is built on top of FORTRAN it cannot hope to provide the level of integration between program design and data structure typical of more modern languages, but by the use of data structure definitions (called TEMPLATES in JAZELLE jargon) and the power of MORTRAN macros, JAZELLE attempts to make the use and manipulation of data structures within programs as unobtrusive as possible.
Date: April 1, 1990
Creator: Johnson, A. S.
Partner: UNT Libraries Government Documents Department

Simulation of tail distributions in electron-positron circular colliders

Description: In addition to the Gaussian shaped core region, particle bunches in electron-positron circular colliders have a rarefied halo region of importance in determining beam lifetimes and backgrounds in particle detectors. A method is described which allows simulation of halo particle distributions.
Date: February 1, 1992
Creator: Irwin, J.
Partner: UNT Libraries Government Documents Department

Stapp`s quantum dualism: The James/Heisenberg model of consciousness

Description: Henry Stapp attempts to resolve the Cartesian dilemma by introducing what the author would characterize as an ontological dualism between mind and matter. His model for mind comes from William James` description of conscious events and for matter from Werner Heisenberg`s ontological model for quantum events (wave function collapse). His demonstration of the isomorphism between the two types of events is successful, but in the author`s opinion fails to establish a monistic, scientific theory. The author traces Stapp`s failure to his adamant rejection of arbitrariness, or `randomness`. This makes it impossible for him (or for Bohr and Pauli before him) to understand the power of Darwin`s explanation of biology, let along the triumphs of modern `neo-Darwinism`. The author notes that the point at issue is a modern version of the unresolved opposition between Leucippus and Democritus on one side and Epicurus on the other. Stapp`s views are contrasted with recent discussions of consciousness by two eminent biologists: Crick and Edelman. They locate the problem firmly in the context of natural selection on the surface of the earth. Their approaches provide a sound basis for further scientific work. The author briefly examines the connection between this scientific (rather than ontological) framework and the new fundamental theory based on bit-strings and the combinatorial hierarchy.
Date: February 18, 1994
Creator: Noyes, H. P.
Partner: UNT Libraries Government Documents Department