28,012 research outputs found

    Single particle momentum and angular distributions in hadron-hadron collisions at ultrahigh energies

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    The forward-backward charged multiplicity distribution (P n sub F, n sub B) of events in the 540 GeV antiproton-proton collider has been extensively studied by the UA5 Collaboration. It was pointed out that the distribution with respect to n = n sub F + n sub B satisfies approximate KNO scaling and that with respect to Z = n sub F - n sub B is binomial. The geometrical model of hadron-hadron collision interprets the large multiplicity fluctuation as due to the widely different nature of collisions at different impact parameters b. For a single impact parameter b, the collision in the geometrical model should exhibit stochastic behavior. This separation of the stochastic and nonstochastic (KNO) aspects of multiparticle production processes gives conceptually a lucid and attractive picture of such collisions, leading to the concept of partition temperature T sub p and the single particle momentum spectrum to be discussed in detail

    A statistical mechanics framework for multi-particle production in high energy reactions

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    We deduce the particle distributions in particle collisions with multihadron-production in the framework of mechanical statistics. They are derived as functions of x, P_T^2 and the rest mass of different species for a fixed total number of all produced particles, inelasticity and total transverse energy. For P_T larger than the mass of each particle we get the behaviour \frac{dn_i}{dP_T} \sim \sqrt{P_T} e^{-\frac{P_T}{T_H}} Values of _\pi, _K, and _{\bar{p}} in agreement with experiment are found by taking T_H=180MeV (the Hagedorn temperature).Comment: 9 pages, RevTe

    Customer Concerns about Uncertainty and Willingness to Pay in Leasing Solar Power Systems

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    Although solar power systems are considered as one of the most promising renewable energy sources, some uncertain factors as well as the high cost could be barriers which create customer resistance. Leasing instead of purchase, as one type of product service system, could be an option to reduce consumer concern on such issues. This study focuses on consumer concerns about uncertainty and willingness to pay for leasing solar power systems. Conjoint analysis method is used to find part worth utilities and estimate gaps of willingness to pay between attribute levels, including various leasing time lengths. The results show the part worth utilities an d relative importance of four major attributes, including leasing time. Among concerns about uncertainties, government subsidy, electricity price, reliability, and rise of new generation solar power systems were found to be significantly related to the additional willingness-to-pay for a shorter leasing time. Cluster analysis is used to identify two groups standing for high and low concerns about uncertainty. People with more concerns tend to pay more for a shorter lease time

    Momentum Distribution for Bosons with Positive Scattering Length in a Trap

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    The coordinate-momentum double distribution function ρ(r,p)d3rd3p\rho ({\bf r}, {\bf p}) d^{3}rd^{3}p is calculated in the local density approximation for bosons with positive scattering length aa in a trap. The calculation is valid to the first order of aa. To clarify the meaning of the result, it is compared for a special case with the double distribution function ρwd3rd3p\rho_{w}d^{3} rd^{3}p of Wigner.Comment: Latex fil

    Surface wave scattering at nonuniform fluid interfaces

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    Effects of spatially varying interfacial parameters on the propagation of surface waves are studied. These variations can arise from inhomogeneities in coverage of surface active substances such as amphiphillic molecules at the fluid/gas interface. Such variations often occur in phase coexistence regions of Langmuir monolayers. Wave scattering from these surface inhomogeneities are calculated in the limit of small variations in the surface parameters by using the asymptotic form of surface Green's functions in the first order Born approximation. When viscosity and variations in surface elastic moduli become important, modes other than transverse capillary waves can change the characteristics of propagation. Scattering among these modes provides a mechanism for surface wave attenuation in addition to viscous damping on a homogeneous surfactant covered interface. Experimental detection of waves attenuation and scattering is also discussed.Comment: 11 pages; 8 figures on reques

    Broadband rotor noise analyses

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    The various mechanisms which generate broadband noise on a range of rotors studied include load fluctuations due to inflow turbulence, due to turbulent boundary layers passing the blades' trailing edges, and due to tip vortex formation. Existing analyses are used and extensions to them are developed to make more accurate predictions of rotor noise spectra and to determine which mechanisms are important in which circumstances. Calculations based on the various prediction methods in existing experiments were compared. The present analyses are adequate to predict the spectra from a wide variety of experiments on fans, full scale and model scale helicopter rotors, wind turbines, and propellers to within about 5 to 10 dB. Better knowledge of the inflow turbulence improves the accuracy of the predictions. Results indicate that inflow turbulence noise depends strongly on ambient conditions and dominates at low frequencies. Trailing edge noise and tip vortex noise are important at higher frequencies if inflow turbulence is weak. Boundary layer trailing edge noise, important, for large sized rotors, increases slowly with angle of attack but not as rapidly as tip vortex noise