10444896
Active cooling control of the CLEO detector using a hydrocarbon coolant farm
Abstract We describe a novel approach to particle-detector cooling in which a modular farm of active coolant-control platforms provides independent and regulated heat removal from four recently upgraded subsystems of the CLEO detector: the ring-imaging Cherenkov detector, the drift chamber, the silicon vertex detector, and the beryllium beam pipe. We report on several aspects of the system: the suitability of using the aliphatic-hydrocarbon solvent PF TM -200IG as a heat-transfer fluid, the sensor elements and the mechanical design of the farm platforms, a control system that is founded upon a commercial programmable logic controller employed in industrial process-control applications, and a diagnostic system based on virtual instrumentation. We summarize the system's performance and point out the potential application of the design to future high-energy physics apparatus.
18120813
Decays of B_s Mesons and b Baryons: A Review of Recent First Observations and Branching Fractions
Recent rate measurements of B{sub s}{sup 0} mesons and {Lambda}{sub b}{sup 0} baryons produced in {radical}s = 1.96 TeV proton-antiproton and {Upsilon}(5S) electron-positron collisions are reviewed, including the first observations of six new decay modes: B{sub s}{sup 0} {yields} D{sub s}{sup +} K{sup -} (CDF), B{sub s}{sup 0} {yields} D{sub s}{sup -} D{sub s}{sup +} (CDF), B{sub s}{sup 0} {yields} D{sub s1}{sup -}(2536){mu}{sup +} {nu}{sub {mu}} X (DZero), B{sub s}{sup 0} {yields} {phi}{gamma} (Belle)< {Lambda}{sub b}{sup 0} {yields} p{pi}{sup -} (CDF), and {Lambda}{sub b}{sup 0} {yields} pK{sup -} (CDF). Also examined are branching-fraction measurements or limits for the B{sub s}{sup 0} {yields} D{sub s}{sup (*)} D{sub s}{sup (*)} modes (Belle, CDF, and DZero), the B{sub s}{sup 0} {yields} {gamma}{gamma} radiative penguin decay (Belle), and three two-body charmless B{sub s}{sup 0} meson decay channels (CDF). Implications for the phenomenology of electroweak and QCD physics, as well as searches for physics beyond the Standard Model, are identified where applicable.
119090553
A Study of Exclusive Nonleptonic Decays of $B$ Mesons into Final States of Strange Mesons and 1S or 2S Charmonia
[abridged] Bound states of heavy quarks can serve as a laboratory for inquiry into the behaviour of the fundamental strong and electroweak interactions. This thesis examines observations of B0, B0bar, and B+- mesons produced in proton-antiproton collisions at centre-of-mass energies of sqrt{s}=1.8 TeV. The B-meson decay products are recorded using the Collider Detector at Fermilab (CDF) located on the Tevatron collider at Fermilab, USA. Four B-meson decays and their charge conjugates are studied: B+ -> J/psi K+, B0 -> J/psi K*(892)0, B+ -> psi(2S) K+, and B0 -> psi(2S) K*(892)0. Using a data sample corresponding to a time-integrated luminosity of (109 +- 7)/pb, statistically significant signals are observed in all the channels. Topological similarities between the B decays are exploited to measure the six relative branching fractions (Br) of each channel with respect to the other channels. The ratios involving the B+ -> J/psi K+ mode are Br(B0 -> J/psi K*(892)0) / Br(B+ -> J/psi K+) = 1.76 +- 0.14[stat] +- 0.15[syst], Br(B+ -> psi(2S) K+) / Br(B+ -> J/psi K+) = 0.558 +- 0.082[stat] +- 0.056[syst], and Br(B0 -> psi(2S) K*(892)0) / Br(B+ -> J/psi K+) = 0.908 +- 0.194[stat] +- 0.100[syst]. The indicated uncertainties are statistical and systematic, respectively. In ratios involving unlike B-meson species, equal production rates for B+ and B0 mesons have been assumed. The B+ -> psi(2S) K+ and B0 -> psi(2S) K*(892)0 reconstructions are the first observations of these processes at a hadron collider. The branching-fraction ratio measurements are consistent with phenomenological predictions that employ the factorization Ansatz, and the derived absolute branching-fraction measurements are consistent with previous world-average limits and values from e+e- colliders. [abridged]
119245772
Strong longitudinal color-field effects in pp collisions at energies available at the CERN Large Hadron Collider
We study the effect of strong longitudinal color fields (SCF) in p + p reactions up to Large Hadron Collider (LHC) energies in the framework of the hijing/BB (v2.0) model that combines (collinear factorized) perturbative quantum chromodynamics multiple minijet production with soft longitudinal string excitation and hadronization. The default vacuum string tension, {kappa}{sub 0} = 1 GeV/fm, is replaced by an effective energy-dependent string tension, {kappa}(s)={kappa}{sub 0}(s/s{sub 0}){sup 0.06} that increases monotonically with center-of-mass energy. The exponent {lambda}=0.06 is found sufficient to reproduce well the energy dependence of multiparticle observables in the Relativistic Heavy Ion Collider, Tevatron, as well as recent LHC data. This exponent is half of that predicted by the color glass saturation (CGC) model, {lambda}{sub CGC}=0.115, where gluon fusion multiparticle production mechanisms are assumed. In hijing/BB (v2.0), the rapid growth of dN{sub ch}/d{eta} with energy is due to the interplay of copious minijet production with increasing SCF contributions. The large (strange) baryon-to-meson ratios measured at Tevatron energies are well described. A significant enhancement of these ratios is predicted up to the highest LHC energy (14 TeV). The effect of JJ loops and SCF on baryon-antibaryon asymmetry, and its relation to baryon number transport, is also discussed.
51843235
The ATLAS Data Acquisition and Trigger: concept, design and status
This article presents the base-line design and implementation of the ATLAS Trigger and Data Acquisition system, in particular the Data Flow and High Level Trigger components. The status of the installation and commissioning of the system is also presented.
199676973
Can hyperon/meson ratios in rare high multiplicity pp collisions at Large Hadron Collider energies provide signatures of mini-quark-gluon plasma formation?
122995152
S-wave eigenvalues of the Lippmann-Schwinger kernel for the exponential potential
It is shown that the S-wave eigenvalues of the Lippmann-Schwinger kernel for the exponential potential can be determined from the zeros of a Bessel function whose order is energy dependent. An asymptotic expansion is obtained for the leading eigenvalue at negative energies.
120759295
Finite difference solution of the partial-wave Schrodinger equation
A method is developed for the numerical determination of bound states and the eigenvalues of the Lippmann-Schwinger kernel for any local interaction. The eigenvalues of the scattering kernel are analytically continued from negative energies to positive energies by means of Pade approximants. The method is applied to calculations on low energy neutron-proton scattering.
117548189
Two-body off-shell potential scattering
SummaryA method is developed for the calculation of two-body scattering amplitudes for a wide class of local potentials, both on and off the energy shell. Padé approximants, ratios of polynomials in both the energy and the off-shell momenta, are obtained for the terms in Weinberg’s separable expansion of theT-matrix, giving a simple representation of the matrix elements for all off-shell momenta, and energies throughout the complex plane. The approximants are exact for the Hulthén potential, and results are given for the Yukawa potential.RiassuntoSi sviluppa un metodo per il calcolo delle ampiezze di scattering di due corpi per un’ampia classe di potenziali locali, sia sopra che fuori dello strato dell’energia. Si ottengono gli approssimanti di Padé, i rapporti dei polinomi dell'energia e degli impulsi fuori dallo strato, per i termini nello sviluppo separabile di Weinberg della matriceT, che dà una semplice rappresentazione degli elementi di matrice per tutti gli impulsi fuori dallo strato, e le energie su tutto il piano complesso. Gli approssimanti risultano esatti per il potenziale di Hulthén; si forniscono anche i risultati per il potenziale di Yukawa.РезюмеРазвивается метод для вычисления двух-частичных амплитуд расселния для широкого класса локальных потенциалов на и вне энергетической поверхности. Получаются Падз аппроксимации, отношения полиномов и по энергии и по импульсу вне массовой поверхности для членов в разделяемом разложении Вейнберга дляT-матрицы, которое дает простое представление матричных элементов для любых импульсов вне массовой поверхности и энергий во всей комплексной области. Аппроксимации являются точными для потенциала Хюльтена, и приводятся результаты для потенциала юкавы.
120039280
Approximations to the Newton potential
Explicit expressions are obtained for Newton's (1962) solution to the inverse scattering problem in the approximations where up to two phase shifts are treated exactly and the rest to first order.
121133729
The off-shell Born approximation for local potentials
Assuming the existence of a (possibly energy-dependent) local potential satisfying 0 integral infinity mod V(r) mod r2dr 2k.