Search for the KL-->pi 0 pi 0 e+e- decay in the KTeV experiment

The recent discovery of a large CP violating asymmetry in KL-->pi+pi-e+e- mode has prompted us to seach for the associated KL-->pi 0 pi 0 e+e- decay mode in the KTeV-E799 experiment at Fermilab. In 2.7 x 10(11) K(L) decays, one candidate event has been observed with an expected background of 0.3 event, resulting in an upper limit for the KL-->pi 0 pi 0 e+e- branching ratio of 6.6 x 10(-9) at the 90% C.L.     

Rheological analysis and quantitative evaluation of wet kneaded wax matrix

The properties of the wet kneaded wax matrix were evaluated using a compression tester, whereby a newly proposed sigma index for the plastic deformation was assessed in the pressure transmission diagram. The sigma index was indicative of a characteristic of the plastic yield point in the rheological behavior, and presented an initial and abrupt deformation of wet kneaded mass when the wet kneaded mass was subjected to the pressure. The value of sigma index was confirmed to decrease along with an increase in the plasticity of wet kneaded mass. The wet mass of wax matrix was prepared under various kneading time, and then extruded. The properties of the extruded granules such as pore volume, strength and dissolution were investigated. As a result, it was found that the sigma index decreased with an increase in kneading time. The granules with small value of sigma index showed few porosities, large strength and slow dissolution. It was demonstrated that the sigma index linked the characteristics of wet kneaded mass to the dissolution and the other granule properties. Existence of this link was revealed by sigma index evaluation relevant to the plasticity. The sigma index could be a decisive criterion to permit an in-process evaluation of the kneading progress quantitatively, and also useful for anticipating the dissolution of the final granules roughly.     

A comment on the phase transition in RbCaF3

The structural phase transition in RbCaF₃ has been examined by observing super lattice points by means of neutron diffraction. There is one structural phase transition with the R₂₅^x soft mode phonon condensation up to 4.2 K. The rotation angle of CaF₆ octahedra, Ø, is calculated as 8.64 degrees at 60 K. The temperature dependence of Ø is also given.     

Thermal decomposition of ethane in shock waves

The thermal decomposition of ethane was studied behind reflected shock waves over the temperature range 1200–1700 K and over the pressure range 1.7?2.5 atm, by both tracing the time variation of absorption at 3.39 μm and analyzing the concentration of the reacted gas mixtures. The mechanism to interpret well not only the earlier stage of C₂H₆ decomposition, but also the later stage was determined. The rate constant of reactions, C₂H₆ → CH₃ + CH₃, C₂H₆ + C₂H₃ → C₂H₅ + C₂H₄, C₂H₅ → C₂H₄ + H were calculated. The rate constants of the other reactions were also discussed.     

Objective and subjective evaluations of twenty-three opera houses in Europe, Japan, and the Americas

The room acoustical parameters, reverberation time RT, early decay time EDT, clarity factor C80, bass ratio BR, strength G, interaural cross-correlation coefficient IACC, and initial-time-delay gap ITDG [definitions in Hidaka et al., J. Acoust. Soc. Am. 107, 340-354 (2000) and Beranek, Concert and Opera Halls: How They Sound (Acoustical Society of America, New York, 1996)], were measured in 23 major opera houses under unoccupied conditions in 11 countries: Argentina, Austria, Czech, France, England, Germany, Hungary, Italy, Japan, The Netherlands, and the USA. Questionnaires containing rating scales on the acoustical quality of 24 opera houses were mailed to 67 conductors, 22 of whom responded. The objective measurements were analyzed for reliability and orthogonality, and were related to the subjective responses. Presented are (a) the rankings of 21 opera houses each rated by at least 6 conductors for acoustical quality as heard by them both in the audience areas and in the pit; (b) relations between objective room acoustical parameters and subjective ratings; (c) findings of the most important of the parameters for determining acoustical quality: RT (or EDT), G(M), ITDG, [1 - IACC(E3)], texture (appearance of reflectrograms in the first 80-100 ms after arrival of the direct sound), a lower limiting value for BR, and major concern for diffusion and avoidance of destructive characteristics (noise, vibration, echoes, focusing, etc.); (d) the differences between average audience levels with and without enclosed stage sets; and (e) the differences between average levels in audience areas for sounds from the stage and from the pit.     

A new definition of boundary point between early reflections and late reverberation in room impulse responses

The early reflections in the room impulse response are usually defined as those observed within the initial 80 ms after the arrival of the direct sound, after which time the sound field is called reverberant. This number was chosen from measurements of other functions in a limited number of halls. In order to give an objective foundation to this time separation and to establish a physical indicator for it, a new method is proposed that defines a "transition time t(L)," which is the time at which the energy correlation between the direct plus initial sound and the subsequent decaying sound first achieves a specified low value. For various halls this number is shown and its relevance as a new parameter is discussed.     

Shock tube and modeling study of 1,3-butadiene pyrolysis

1,3-Butadiene (1,3-C₄H₆) was heated behind reflected shock waves over the temperature range of 1200–1700 K and the total density range of 1.3 × 10⁻⁵ −2.9 × 10⁻⁵ mol/cm³. Reaction products were analyzed by gas-chromatography. The concentration change of 1,3-butadiene was followed by UV kinetic absorption spectroscopy at 230 nm and by quadrupole mass spectrometry. The major products were C₂H₂, C₂H_4, C₄H₄, and CH₄. The yield of CH₄ for a 0.5% 1,3-C₄H₆ in Ar mixture was more than 10% of the initial 1.3-C₄H₆ concentration above 1500 K. In order to interpret the formation of CH₄ successfully, it was necessary to include the isomerization of 1,3-C₄H₆ to 1,2-butadiene (1,2-C₄H₆) and to include subsequent decomposition of the 1,2-C₄H₆ to C₃H₃ and CH₃. The present data and other shock tube data reported over a wide pressure range were qualitatively modeled with a 89 reaction mechanism, which included the isomerizations of 1,3-C₄H₆ to 1,2-C₄H₆ and 2-butyne (2-C₄H₆). © 1996 John Wiley & Sons, Inc.     

Photocatalyzed degradation of polymers in aqueous semiconductor suspensions. I. Photooxidation of solid particles of polyvinylchloride

The photocatalyzed oxidative decompositions of solid particles of polyvinylchloride (PVC; size about 100 to 200 μm), of the polyvinylidene chloride copolymer (95% PVC/5% PVLC; size ∼ 400–600 μm), and a PVC film have been examined in suspensions of titania and zinc oxide illuminated by UV light and/or by natural sunlight. Dechlorination and evolution of carbon dioxide were monitored, the latter occurring by the intermediacy of acetic and formic acids. The photodegradation of polymer specimens was enhanced in TiO₂/water media by such added oxidants as hydrogen peroxide and potassium persulfate. Photocorrosion of these particulates was also examined by scanning electron microscopy. © 1996 John Wiley & Sons, Inc.     

Acoustical design of the Tokyo Opera City (TOC) concert hall, Japan

The Tokyo Opera City concert hall seats 1632, volume 15 300 m3, and reverberation time, with audience and orchestra, 1.95 s. As part of the design process, measurements on CAD computer and 1:10 wooden models of the hall and full-sized materials samples were conducted over a 5-yr. period. The hall in plan is rectangular. The ceiling is a distorted pyramid, with its peak 28 m above the main floor and nearer the stage than the rear of the hall. This unique shape was analyzed on the models so that all interior surfaces combine to distribute sources on the stage uniformly over the seating areas and to yield optimum values for reverberation time (RT), early decay time (EDT), interaural cross-correlation coefficient (IACCE3), bass ratio (BR), initial-time-delay gap (ITDG), strength (G), and sound diffusion index (SDI) [for definitions see L. Beranek, Concert and Opera Halls: How They Sound (Acoustical Society of America, Woodbury, NY, 1996)]. On the long ceiling facing the stage, Schroeder QRD diffusers provide diffusion, eliminate a possible echo, and strengthen lateral reflections. Performers and critics judge the acoustics excellent.