467 research outputs found
Scattering Uniformity Measurements and First Reflection Analysis in a Large Nonanechoic Environment
Following previous investigation, carried out at the University of Parma in 1999 and 2000, LAE (Laboratory of
Acoustics and Electroacoustics) started a new measurement campaign to compare with the original results on the
same type of diffusor panels, to verify AES-4id-2001 measurement standard and to investigate the nature of
scattering phenomena in more detail. Measurements are conducted on the floor of a large closed space to obtain a
reflection free time window, long enough to study the first reflection from the panel; the use of sine sweep excitation
signals instead of the recommended MLS ones permits to ameliorate the acquisition process. The present article
discusses research background studies and the results from the first round of measurements
Perceived room size and source distance in five simulated concert auditoria
Room impulse responses (stereophonic and binaural) were recorded using identical procedures in five concert auditoria: the large, medium and small halls of Rome's Parco della Musica, Parma's Auditorium Paganini, and Kirishima's Miyama Conseru. A subjective test was conducted, using an anechoic recording of a piano accordion convolved with these impulse responses, and reproduced over four audio systems (binaural headphones, conventional stereophony, stereo dipole and double stereo dipole). The frequency responses of these playback systems were matched, and the playback level was realistic for the instrument and auditoria. Results indicate that the audio system can significantly affect distance estimation and realism judgments (with a non-significant effect on room size ratings). The situation (auditorium and seat position) significantly affects distance estimations and room size ratings (but not realism ratings). Room acoustical parameters were determined from for each situation, and relationships between these and the auditory distance and room size judgments were investigated. Auditory distance perception is primarily correlated (negatively) to the reproduced sound pressure level. Results for perceived room size are more complex, and demand further research for interpretation. Results tentatively indicate that among these non-individualized two-channel systems, the single stereo dipole system provides a plausible reproduction of the auditorium acoustical environment for the purpose of subjective assessment
Three-Dimensional Acoustic Displays In A Museum Employing WFS (Wave Field Synthesis) And HOA (High Order Ambisonics)
The paper describes the sound systems and the listening rooms installed in the new "museum
of reproduced sound", actually being built in Parma, restoring an ancient church. The museum
is devoted to the exposition of a huge collection of antique radios and gramophones, but it
will also exploit the frontiers of modern methods for immersive surround reproduction: WFS
and HOA.
In the main hall, a large planar WFS loudspeaker array is employed for inviting the visitors to
enter the world of sound reproduction, providing stunning effects and emotional sounds
enveloping them from many directions.
At the end of the exposition path, a special HOA space is employed for showing the recent
developments of recording/reproduction methods started from the Ambisonics concept,
capable of creating natural reproduction of sport events, live music and other immersive
acoustical experiences; in this room also a binaural/transaural system is available.
A second, larger listening room capable of 30seats is equipped with a horizontal WFS array
covering the complete perimeter of the room. The paper describes the technology employed,
the problems encountered due to the difficult acoustical conditions (the museum was formerly
a church), and the novel software tools developed for the purpose on LINUX platforms
Measurement of J/Psi and Psi(2S) Polarization in ppbar Collisions at sqrt(s) = 1.8 TeV
We have measured the polarization of J/Psi and Psi(2S) mesons produced in
p\bar{p} collisions at \sqrt{s} = 1.8 TeV, using data collected at CDF during
1992-95.
The polarization of promptly produced J/Psi [Psi(2S)] mesons is isolated from
those produced in B-hadron decay, and measured over the kinematic range 4[5.5]
< P_T < 20 GeV/c and |y| < 0.6. For P_T \gessim 12 GeV/c we do not observe
significant polarization in the prompt component.Comment: Revised version, accepted for publication in Physical Review Letter
Measurement of the Strong Coupling Constant from Inclusive Jet Production at the Tevatron Collider
We report a measurement of the strong coupling constant, ,
extracted from inclusive jet production in collisions at
1800 GeV. The QCD prediction for the evolution of with
jet transverse energy is tested over the range 40<<450 GeV using
for the renormalization scale. The data show good agreement with QCD in
the region below 250 GeV. In the text we discuss the data-theory comparison in
the region from 250 to 450 GeV. The value of at the mass of the
boson averaged over the range 40<<250 GeV is found to be
. The associated theoretical uncertainties are mainly due to the choice
of renormalization scale (^{+6%}_{-4%}) and input parton distribution
functions (5%).Comment: 7 pages, 3 figures, using RevTeX. Submitted to Physical Review
Letter
Search for the Supersymmetric Partner of the Top-Quark in Collisions at
We report on a search for the supersymmetric partner of the top quark (stop)
produced in events using of
collisions at recorded with the Collider Detector at
Fermilab. In the case of a light stop squark, the decay of the top quark into
stop plus the lightest supersymmetric particle (LSP) could have a significant
branching ratio. The observed events are consistent with Standard Model production and decay. Hence, we set limits on the branching ratio of
the top quark decaying into stop plus LSP, excluding branching ratios above 45%
for a LSP mass up to 40 {\rm GeV/c}.Comment: 11 pages, 4 figure
Search for Narrow Diphoton Resonances and for gamma-gamma+W/Z Signatures in p\bar p Collisions at sqrt(s)=1.8 TeV
We present results of searches for diphoton resonances produced both
inclusively and also in association with a vector boson (W or Z) using 100
pb^{-1} of p\bar p collisions using the CDF detector. We set upper limits on
the product of cross section times branching ratio for both p\bar
p\to\gamma\gamma + X and p\bar p\to\gamma\gamma + W/Z. Comparing the inclusive
production to the expectations from heavy sgoldstinos we derive limits on the
supersymmetry-breaking scale sqrt{F} in the TeV range, depending on the
sgoldstino mass and the choice of other parameters. Also, using a NLO
prediction for the associated production of a Higgs boson with a W or Z boson,
we set an upper limit on the branching ratio for H\to\gamma\gamma. Finally, we
set a lower limit on the mass of a `bosophilic' Higgs boson (e.g. one which
couples only to \gamma, W, and Z$ bosons with standard model couplings) of 82
GeV/c^2 at 95% confidence level.Comment: 30 pages, 11 figure
Production of Y(1S) Mesons from chib Decays in pp(bar) Collisions at sqrt(s)=1.8 TeV
We have reconstructed the radiative decays and in collisions
at TeV, and measured the fraction of mesons
that originate from these decays. For mesons with
GeV/, the fractions that come from and
decays are and
, respectively. We have derived the fraction of
directly produced mesons to be .Comment: 13 Pages, 2 figure
Search for a Fourth-Generation Quark More Massive than the Z0 Boson in ppbar Collisions at sqrt(s) = 1.8 TeV
We present the results of a search for pair production of a fourth-generation
charge -1/3 quark (b') in sqrt(s)=1.8 TeV ppbar collisions using 88 pb^(-1) of
data obtained with the Collider Detector at Fermilab. We assume that both
quarks decay via the flavor-changing neutral current process b' -> bZ and that
the b' mass is greater than m_Z + m_b. We studied the decay mode b'b'bar -> ZZ
b bbar where one Z0 decays into e^+e^- or mu^+ mu^- and the other decays
hadronically, giving a signature of two leptons plus jets. An upper limit on
the cross section of ppbar -> b'b'bar times [BR (b' -> bZ)]^2 is established as
a function of the b' mass. We exclude at 95% confidence level a b' quark with
mass between 100 and 199 GeV/c^2 for BR(b' -> bZ) = 100%.Comment: 12 pages, 2 figures, submitted to Phys. Rev. Letters on 9/12/9
Measurement of the p\bar{p}\sqrt{s}$ = 1.8 TeV
We update the measurement of the top production cross section using the CDF
detector at the Fermilab Tevatron. This measurement uses decays to
the final states +jets and +jets. We search for quarks from
decays via secondary-vertex identification or the identification of
semileptonic decays of the and cascade quarks. The background to the
production is determined primarily through a Monte Carlo simulation.
However, we calibrate the simulation and evaluate its uncertainty using several
independent data samples. For a top mass of 175 , we measure
pb and pb using
the secondary vertex and the lepton tagging algorithms, respectively. Finally,
we combine these results with those from other decay channels and
obtain pb.Comment: The manuscript consists of 130 pages, 35 figures and 42 tables in
RevTex. The manuscript is submitted to Physical Review D. Fixed typo in
author lis
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