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High-power vacuum window in WR10

Description: Results are presented for fabrication and test of a WR10 waveguide window, for use in ultra-high vacuum at 91.4 GHz. Low-power bench measurements are compared with analytic and simulation results. Operation at approximately equal to 4-kW peak power, duty factor 10{sup {minus}6} and 10{sup {minus}9}-scale vacuum is noted.
Date: June 28, 1999
Creator: Hill, Marc E
Partner: UNT Libraries Government Documents Department

Recent QCD Results from SLD

Description: We present selected results on strong interaction physics from the SLD experiment at the SLAC Linear Collider. We report on several new studies of 3- and 4-jet hadronic Z{sup 0} decays, in which jets are identified as quark, antiquark or gluon. The 3-jet Z{sup 0} --> b anti-bg rate is sensitive to the b-quark mass; prospects for measuring m{sub b} are discussed. The gluon energy spectrum is measured over the full kinematic range, providing an improved test of QCD and limits on anomalous b anti-bg couplings. The parity violation in Z{sup 0} --> b anti-bg decays is consistent with electroweak theory plus QCD. New tests of T- and CP-conservation at the bbg vertex are performed. A new measurement of the rate of gluon splitting into b anti-b pairs yields g{sub b anti-b} = 0.0031 {+-} 0.0007 (stat.){+-} 0.0006 (syst.) (Preliminary). We also present a number of new results on jet fragmentation into identified hadrons. The B hadron energy spectrum is measured over the full kinematic range using a new, inclusive technique, allowing stringent tests of predictions for its shape and a precise measurement of (xB) = 0.714 {+-} 0.005(stat.) {+-} 0.007(syst.) (Preliminary). A detailed study of correlations in rapidity y between pairs of identified pi{sup {+-}}, K{sup {+-}} and p/anti-p confirms that strangeness and baryon number are conserved locally, and shows local charge conservation between meson-baryon and strange-nonstrange pairs. Flavor-dependent long-range correlations are observed for all combinations of these hadron species, yielding new information on leading particle production. The first study of correlations using rapidities signed such that y > 0 corresponds to the quark direction provides additional new insights into fragmentation, including the first direct observation of baryon number ordering along the q anti-q axis.
Date: September 27, 1999
Creator: Muller, David
Partner: UNT Libraries Government Documents Department

Measurement of subpicosecond electron bunch lengths

Description: A new frequency-resolved bunch-length measuring system has been developed at the Stanford SUNSHINE facility suitable for subpicosecond electron bunches. This method utilizes a far-infrared Michelson interferometer to measure coherent transition radiation emitted from electron bunches through optical auto-correlation. A simple and systematic way has also been developed to include interference effects caused by the beam splitter, so the electron bunch length can be easily obtained from the measurement. This autocorrelation method demonstrates subpicosecond resolving power that cannot be achieved by existing time-resolved methods.
Date: November 1, 1995
Creator: Lihn, Hung-chi; Bocek, D.; Kung, P.; Settakorn, C. & Wiedemann, H.
Partner: UNT Libraries Government Documents Department

1997 Annual Site Environmental Report (ASER)

Description: The SLAC program centers around experimental and theoretical research in elementary particle physics using accelerated electron beams and a broad program of research in atoms and solid-state physics, chemistry, and biology using synchrotron radiation from accelerated electron beams. There is also an active program in the development of accelerators, detectors, and new sources and instrumentation for synchrotron radiation research. The main instrument of research is the 3.2-km linear accelerator (linac) that generates high intensity beams of electrons and positrons up to 50 GeV, which are among the highest energy electron and positron beams available in the world. The linac is also used for injecting electrons and positrons into colliding-beam storage rings for particle physics research. The Positron-Electron Project (PEP) storage ring is about 800 meters in diameter. The PEP program was completed several years ago. PEP is now being upgraded to serve as an Asymmetric B Factory (or PEP-II) that will study the B meson. PEP-II will make use of much of PEP's existing equipment and infrastructure, and is scheduled for completion in 1998. A smaller storage ring, the Stanford Positron-Electron Asymmetric Ring (SPEAR) has its own smaller linac and a booster ring for injecting accelerated beams of electrons. SPEAR is fully dedicated to synchrotron radiation research. The synchrotron light generated by the SPEAR storage ring is used by the Stanford Synchrotron Radiation Laboratory (SSRL) to perform experiments. Scientists from all parts of the United States and from throughout the world participate in the experimental programs at SLAC.
Date: October 1, 1998
Creator: Holden, Gene
Partner: UNT Libraries Government Documents Department

CP Violation and B Physics

Description: This is a quick review of CP non-conservation in B physics. Several methods are described for testing the Kobayashi-Maskawa single phase origin of CP violation in B decays, pointing out some limitations due to hadronic uncertainties. A few characteristic signatures of new physics in B decay asymmetries are listed.
Date: August 17, 1999
Creator: Gronau, Michael
Partner: UNT Libraries Government Documents Department

Supersymmetry: Theory

Description: If supersymmetric particles are discovered at high-energy colliders, what can one hope to learn about them? In principle, the properties of supersymmetric particles can give a window into the physics of grand unification, or of other aspects of interactions at very short distances. In this article, the author sketches out a systematic program for the experimental study of supersymmetric particles and point out the essential role that e{sup +}e{sup {minus}} linear colliders will play in this investigation.
Date: March 1, 1996
Creator: Peskin, M.E.
Partner: UNT Libraries Government Documents Department

Transverse multibunch modes for non-rigid bunches, including mode coupling

Description: A method for computing transverse multibunch growth rates and frequency shifts in rings, which has been described previously, is applied to the PEP-II B factory. The method allows multibunch modes with different internal-bunch oscillation modes to couple to one another, similar to single-bunch mode coupling. Including coupling between the multibunch modes gives effects similar to those seen in single-bunch mode coupling. These effects occur at currents that are lower than the single-bunch mode coupling threshold.
Date: August 1, 1995
Creator: Bert, J.S. & Ruth, R.D.
Partner: UNT Libraries Government Documents Department

Study of deep inelastic scattering of polarized electrons off polarized deuterons

Description: This thesis describes a 29GeV electron - nucleon scattering experiment carried out at Stanford Linear Accelerator Center (SLAC). Highly polarized electrons are scattered off a polarized ND{sub 3} target. Scattered electrons are detected by two spectrometers located in End Station A (ESA) at angles of 4.5{degrees} and 7{degrees} with respect to the beam axis. We have measured the spin structure function g{sub 1} of deuteron over the range of 0.029 < x < 0.8 and 1. 0 < Q{sup 2} < 12.0(GeV/c){sup 2}. This integral indicates a discrepancy of more than three standard deviations from the prediction of the Ellis-Jaffe sum rule, 0.068{+-}0.005 at Q{sup 2} = 3.0(GeV/c){sup 2} while our result of g{sub 1}{sup d} in good agreement with SMC results. Combined with g{sub 1} of the proton, the measurement of {integral}{sub 0}{sup 1}(g{sub 1}{sup d}-g{sub 1}{sup n}) is 0.169{+-}0.008. We also obtained the strong coupling constant at Q{sup 2} = 3.0(GeV/c){sup 2} to be 0.417{sub -0.110}{sup +0.086}, using the power correction for the sum rule up to third order of {alpha}{sub s}. This result is in agreement with the strong coupling constant {alpha}{sub s}(Q{sup 2}) = 3.0(GeV/c{sup 2}) obtained from various experiments. Using our deuteron results and the axial vector couplings of hyperon decays, the total quark polarization along the nucleon spin is found to be 0.286{+-}.055, implying that quarks carry only 30% of the nucleon spin. The strange sea quark polarization is also determined to be -0.101 {+-} .023. These measurements are in agreement with other experiments and provide the world`s most precise measurement of these quark polarizations. 80 refs., 151 figs., 23 tabs.
Date: March 1, 1996
Creator: Kuriki, M.
Partner: UNT Libraries Government Documents Department

Bit-string physics: A novel theory of everything

Description: We encode the quantum numbers of the standard model of quarks and leptons using constructed bitstrings of length 256. These label a grouting universe of bit-strings of growing length that eventually construct a finite and discrete space-time with reasonable cosmological properties. Coupling constants and mass ratios, computed from closure under XOR and a statistical hypothesis, using only {h_bar}, c and m{sub p} to fix our units of mass, length and time in terms of standard (meterkilogram-second) metrology, agree with the first four to seven significant figures of accepted experimental results. Finite and discrete conservation laws and commutation relations insure the essential characteristics of relativistic quantum mechanics, including particle-antiparticle pair creation. The correspondence limit in (free space) Maxwell electromagnetism and Einstein gravitation is consistent with the Feynman-Dyson-Tanimura ``proof.``
Date: August 1, 1994
Creator: Noyes, H.P.
Partner: UNT Libraries Government Documents Department

1995 Site environmental report, January 1995--December 1995

Description: This report provides information about environmental programs and compliance with environmental regulations in calendar year 1995 (CY95) at the Stanford Linear Accelerator Center (SLAC). SLAC is a national laboratory operated by Stanford University under contract with the US Department of Energy (DOE) and is devoted to experimental and theoretical research in elementary particle physics, in basic sciences using synchrotron radiation, and in accelerator physics and technology. SLAC`s Environment, Safety, and Health (ES&H) Division consists of five departments and a Program Planning Office (PPO). Their shared goal is to help ensure that SLAC operates in compliance with federal, state, and local regulations, as well as DOE Orders related to environment, safety, and health. The five departments are: (1) Environmental Protection and Restoration (EPR), (2) Operational Health Physics (OHP), (3) Radiation Physics (RP), (4) Safety, Health, and Assurance (SHA), and (5) Waste Management (WM). The EPR Department oversees the majority of SLAC`s environmental programs, including programs for environmental restoration; waste minimization; air quality; storm water and industrial wastewater; polychlorinated biphenyls (PCBs); and groundwater. The WM Department coordinates disposal of hazardous, radioactive, and mixed waste. The OHP Department, in cooperation with the EPR Department, oversees environmental radiological monitoring and dosimetry at SLAC. The SHA Department oversees quality assurance for SLAC`s environmental activities. The RP Department conducts beam checkouts of new experiments to ensure shielding adequacy for the protection of the workers and members of the general public. The most significant information in this report is summarized briefly in the following sections.
Date: September 1, 1996
Partner: UNT Libraries Government Documents Department

Z{sup 0} pole direct measurements of the parity violation parameters A{sub b} and A{sub c} at SLD

Description: This report presents three different techniques used at SLD to measure directly the parity violation parameters of Zb{bar b} and Zc{bar c} couplings from the left-right forward-backward asymmetries. The results have been obtained using 150,000 hadronic Z{sup 0} decays accumulated during the 1993-95 runs with high electron beam polarization.
Date: September 1, 1996
Creator: Mancinelli, G.
Partner: UNT Libraries Government Documents Department

Radiation calculations and shielding considerations for the design of the Next Linear Collider

Description: The authors describe some of the work that they have done as a contribution to the Next Linear Collider (NLC) Zeroth-Order Design Report (ZDR), with specific emphasis placed on radiation-protection issues. However, because of the very nature of this machine--namely, extremely-small beam spots of high intensity--a new approach in accelerator radiation-protection philosophy appears to be warranted. Accordingly, the presentation will first take a look at recent design studies directed at protecting the machine itself, since this has resulted in a much better understanding of the very short exposure times involved whenever beam is lost and radiation sources are created. At the end of the paper, the authors suggest a Beam Containment System (BCS) that would provide an independent, redundant guarantee that exposure times are, indeed, kept very short. This, in turn, has guided them in the determination of the transverse shield thickness for the machine.
Date: November 1, 1996
Creator: Nelson, W.R.; Rokni, S.H. & Vylet, V.
Partner: UNT Libraries Government Documents Department

Wire ageing with the TEA photocathode

Description: Recently several RICH protypes successfully tested a gaseous TEA photocathode. However, its wire ageing behavior is unknown. In principle, TEA is a more strongly bonded molecule than TMAE, and, as a result, one would expect better wire ageing behavior. This paper explores this question.
Date: June 1, 1996
Creator: Va`vra, J.
Partner: UNT Libraries Government Documents Department

Measurement of the B{sup +} and B{sup 0} lifetimes from semileptonic decays at SLD

Description: The lifetimes of B{sup +} and B{sup 0} mesons have been measured using a sample of 150,000 hadronic Z{sup 0} decays collected by the SLD experiment at the SLC between 1993 and 1995. The analysis identifies the semileptonic decays of B mesons with high (p,p{sub t}) leptons and reconstructs the B meson decay length and charge by vertexing the lepton with a partially reconstructed D meson. This method results in a sample of 634 (584) charged (neutral) decays with high charge purity. A maximum likelihood fit finds: {tau}{sub B{sup +}} = 1.60{sub {minus}0.11}{sup +0.12}(stat) {+-} 0.06(syst) ps, {tau}{sub B{sup 0}} = 1.55{sub {minus}0.12}{sup +0.13}(stat) {+-} 0.09(syst) ps, and the ratio {tau}{sub B{sup +}}/{tau}{sub B{sup 0}} = 1.03{sub {minus}0.13}{sup +0.15}(stat) {+-} 0.08(syst).
Date: July 1, 1996
Partner: UNT Libraries Government Documents Department

Neutral current couplings of leptons to polarized Z{sup O}`s in the SLD experiment

Description: The authors study neutral current couplings of leptons to polarized Z{sup 0}`s in the SLD experiment in terms of the leptonic asymmetry parameters A{sub e}, A{sub {mu}}, and A{sub {tau}}. The authors discuss in detail e{sub L,R}{sup {minus}} + e{sup +} {yields} Z{sup 0} {yields} {mu}{sup {minus}}{mu}{sup +} and {tau}{sup {minus}}{tau}{sup +}, with left (L)- or right (R)-handed polarized electron beams. SLD`s most precise measurement of A{sub e} is shown to result from the left-right cross section asymmetry; A{sub LR}; where the dependence on initial state electronic couplings enable use of essentially all of the data. Comparing A{sub {mu}} and A{sub {tau}} with A{sub e} tests the universality of leptonic couplings. A{sub {mu}} = 0.102 {+-} 0.033 {+-} 0.001, A{sub {tau}} = 0.190 {+-} 0.034 {+-} 0.001, and A{sub e} = 0.148 {+-} 0.016 {+-} 0.002 from these two leptonic channels. If lepton universality is assumed, a combined asymmetry parameter A{sub e{mu}{tau}} = 0.147 {+-} 0.013 results, which directly corresponds to an effective value of the weak mixing angle sin{sup 2}{theta}{sub W}{sup eff} = 0.2315 {+-} 0.0017.
Date: December 1, 1996
Creator: Panvini, R.S
Partner: UNT Libraries Government Documents Department

Notes on lie algebraic analysis of achromats

Description: Normal form technique is a powerful method to analyze the achromat problem. Assume the one cell map M{sub cell} = ARe{sup :h{sub 3}}:{sub e}{sup :h{sub 4}}: A{sup {minus}1}, where h{sub 3},h{sub 4} are the normal forms of the generators of the unit cell map, and A is the nonlinear transformation that brings M{sub cell} into its normal form; then the map of the whole system is M{sub N} = M{sub cell}{sup N} = AR{sup N} A{sup {minus}1} = I, provided that we can set e{sup :h{sub 3}}:, e{sup :h{sub 4}}, and R{sup N} to the identity (or only {delta} dependent) maps. Therefore, the conditions to form an achromat are h{sub 3} and h{sub 4} equal to zero (or {delta} dependent only) and the total linear map is identity. In this report, we will apply these conditions to a FODO array (a simple model system) to make it an achromat. We will start from Hamiltonians and work all the way up to obtain the analytical expressions of the required sextupole and octupole strengths.
Date: January 1, 1995
Creator: Wang, Chunxi & Chao, A.
Partner: UNT Libraries Government Documents Department

Transfer matrices of superimposed magnets and RF cavity

Description: Superimposed magnets often occur in accelerators, such as in the interaction regions of colliders. This note presents the linear transfer matrices of various superimposed magnets. Since readers of this note are probably well informed, the authors simply list the results without derivation. The method used to calculate the linear transfer matrices is outlined elsewhere. The authors list the Hamiltonian H and the corresponding matrix e{sup :-sH:} for several combinations of common magnets (only sector magnets without fringe field) used in accelerators. Magnetic fields and vector potentials (in Coulomb gauge) are also listed for reference. The usual (x, y, s) coordinate system is used. The transfer matrices are for the commonly used canonical variables (x, P{sub x}, y, P{sub y}, z, {delta}). For those cases when the transfer matrices depend on the gauge selection, the authors also list the matrices for the coordinates and kinetic momenta (x, p{sub x}, y, p{sub y}). The magnetic fields and Hamiltonians are correct only up to the order appropriate for linear optics. In this computer age, complicated analytical results may lose their usefulness and attractiveness in many applications. However, the authors hope their exact analytic results to linear order are still useful for particle dynamics studies in superimposed magnet systems.
Date: November 1, 1996
Creator: Wang, Shun-xi & Chao, A.
Partner: UNT Libraries Government Documents Department

The polarization asymmetry in {gamma}e collisions at the NLC and triple gauge Boson couplings

Description: The capability of the NLC in the {gamma}e collider mode to probe the CP-conserving {gamma}WW and {gamma}ZZ anomalous couplings through the use of the polarization asymmetry is examined. When combined with other measurements, very strong constraints on both varieties of anomalous couplings can be obtained. The author shows that these bounds are complementary to those that can be extracted from data taken at the LHC.
Date: September 1, 1996
Creator: Rizzo, T.G.
Partner: UNT Libraries Government Documents Department

Signatures of extended gauge sectors in e{sup +}e{sup {minus}} {r_arrow} {nu}{anti {nu}}{gamma}

Description: The ability of high energy e{sup +}e{sup {minus}} colliders to indirectly probe the existence of heavy new charged gauge bosons via their exchange in the reaction e{sup +}e{sup {minus}} {r_arrow} {nu}{anti {nu}}{gamma} is investigated. It is shown that examination of the resulting photon energy spectrum with polarized beams can extend the W{prime} search reach above the center of mass energy.
Date: March 1, 1997
Creator: Hewett, J.L.
Partner: UNT Libraries Government Documents Department

Study of microwave instability

Description: The microwave instability is usually described by linearizing Vlasov equation in the angle-action variables I, {phi} and assuming that the interaction of azimuthal harmonics {rho}{sub n}(I) of the distribution function {rho} is weak. The argument implied here is that the Hamiltonian flow smears out particles over invariant tori characterized by the action variables, and the remaining azimuthal dependence of the distribution function is small. Indeed, such an approach successfully describes bunch spectrum and the threshold of the microwave instability. However, recently there have been interesting observations of bunch centroid and bunch shape oscillations above instability threshold at LEP and the damping ring at SLAC. There are also indicates that the oscillations sometimes occur in localized region in the longitudinal coordinate instead of affecting the entire longitudinal distribution as one expects by an action-angle analysis. In this paper the authors describe an alternative approach to the problem of bunch stability using decomposition of the Fokker-Plank equation in the system of nonlinear equations for the moments of the distribution function. In particular, this approach allows them to avoid the conventional action-angle decomposition. The physical quantities they are interested in, the moments, are expressed in the Cartesian z {minus} {delta} phase space. To close the infinite hierarchy of moments equations, the authors assume that higher order correlations are small. Although both the action-angle and the Cartesian languages must be equivalent before truncation, they may have different speed of convergence depending on the problem being studied. It is hoped that Cartesian expansion approach would converge faster for the cases corresponding to those observed recently above threshold. The recent experimental observations made them interested in it again. This note is a progress report of their work.
Date: December 1, 1996
Creator: Heifets, S. & Chao, A.
Partner: UNT Libraries Government Documents Department

On wakefields with two-dimensional planar geometry

Description: In order to reach higher acceleration gradients in linear accelerators, it is advantageous to use a higher accelerating RF frequency, which in turn requires smaller accelerating structures. As the structure size becomes smaller, rectangular structures become increasingly interesting because they are easier to construct than cylindrically symmetric ones. One drawback of small structures, however, is that the wakefields generated by the beam in such structures tend to be strong. Recently, it has been suggested that one way of ameliorating this problem is to use rectangular structures that are very flat and to use flat beams. In the limiting case of a very flat planar geometry, the problem resembles a purely two-dimensional (2-D) problem, the wakefields of which have been studied.
Date: October 1, 1996
Creator: Chao, A.W. & Bane, K.L.F.
Partner: UNT Libraries Government Documents Department

RF breakdown studies in X-Band klystron cavities

Description: RF breakdown studies are presently being carried out at SLAC with klystron cavities in a traveling wave resonator (TWR). Different kinds of fabrication methods and several kinds of semiconducting and insulating coatings have been applied to X-Band TM{sub 010} cavities. RF breakdown thresholds up to 250 MV/m have been obtained. Dark current levels were found to be depressed on TiN-coated and single-point diamond turned cavities. A new TM{sub 020} cavity with demountable electrodes has been designed and will be used to test a variety of materials, coatings, and processes. Recent tests of klystron output windows at 119 MW are also presented in this paper.
Date: May 1, 1997
Creator: Xu, X.; Callin, R.S. & Fowkes, W.R.
Partner: UNT Libraries Government Documents Department

Towards a next-to-leading logarithmic result in B {r_arrow} X{sub s}{gamma}

Description: The calculation of the O ({alpha}{sub s}) virtual corrections to the matrix element of the inclusive decay b {r_arrow} s{gamma} is reported. These contributions drastically reduce the large renormalization scale dependence of the leading logarithmic calculation. Combining these results with the preliminary result for the Wilson coefficient C{sub {gamma}} (m{sub b}) calculated recently by Chetyrkin, Misiak, and Muenz, we estimate the branching ratio to be BR(B {r_arrow} X{sub s} {gamma}) = (3.25 {plus_minus} 0.50) x 10{sup {minus}4}.
Date: August 1, 1996
Creator: Greub, C. & Hurth, T.
Partner: UNT Libraries Government Documents Department

Cold test results of a standing wave muffin-tin structure at X-band

Description: A muffin-tin structure is chosen to study high gradient acceleration in the millimeter wavelength range. In order to understand the electromagnetic field characteristics, a standing wave structure operating at a frequency around 11.4 GHz was built. Cold test measurements were performed and results are presented. Comparisons with theoretical predictions based on computer simulation are shown.
Date: November 1, 1996
Creator: Chou, P.J.; Hanna, S.M.; Henke, H.; Menegat, A.; Siemann, R.H. & Whittum, D.
Partner: UNT Libraries Government Documents Department