Event shapes for Au + Au collisions at 11.4 GeV/ital c per nucleon were studied over nearly the full solid angle with the E877 apparatus. The analysis was performed by Fourier expansion of azimuthal ...distributions of the transverse energy (ital Esub ital T) measured in different pseudorapidity intervals. For semicentral collisions a pronounced event anisotropy is identified with a clear forward-backward anticorrelation. In the forward pseudorapidity interval up to 9% of the ital Esub ital T is in a directed component. The signal decreases for peripheral and very central collisions.
TEC/TRD for the PHENIX experiment Barish, K.N.; Botelho, S.; Chang, W.C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2004, Letnik:
522, Številka:
1
Journal Article
Recenzirano
The TEC/TRD is a set of large multi-wire tracking chambers in the PHENIX experiment with fiber radiators in front of the tracking volume. It provides charged-particle pattern recognition, momentum ...measurement and particle identification through determinations of both ionization energy loss (d
E/d
x) and associated transition radiation (TR) photons. A custom front-end electronics is instrumented with a dual-gain system to read out the d
E/d
x and the TR events. A recirculating gas system for the Xe-based mixture is developed. The device will be fully operational starting in December 2003. It will provide e/π separation with momenta ranging from 0.25 to
50
GeV/c
.
Front-end electronics (FEE) has been developed for the PHENIX time expansion chamber (TEC), a multiwire tracking detector with over 20k readout channels. The FEE for the TEC consists of an analog ...preamplifier-shaping amplifier circuit board, a digital front-end module circuit board plus ancillary support boards for timing, control and communication. Signals from each chamber wire are sampled (/spl sim/40 MHz), digitized, buffered, and then formatted as 64 channel serial data packets to be transmitted via a 1-GHz optical link. Three custom ICs have been designed for this system: 1) octal preamplifier and shaping amplifier with tail cancellation and dual-gain for large dynamic range with full serial control of gain, shaping time and tail; 2) nonlinear 5-b flash ADC with 9-b dynamic range; 3) digital memory unit for programmable delay and memory depth. The FEE has been installed, commissioned, and operated in the PHENIX experiment at Brookhaven National Laboratory.
We present measurements of pion transverse momentum (
p
t) spectra in central Si-nucleus collisions in the rapidity range 2.0 <
y < 5.0 for
p
t down to and including
p
t = 0. The data exhibit an ...enhanced pion yield at low
p
t compared to what is expected for a purely thermal spectral shape. This enhancement is used to determine the Δ resonance abundance at freeze-out. The results are consistent with a direct measurement of the Δ resonance yield by reconstruction of proton-pion pairs and imply a temperature of the system at freeze-out close to 140 MeV.
We present a systematic study of transverse energy (ital Esub ital T) production in collisions of 11.4ital A GeV/ital c Au and 14.6ital A GeV/ital c Si ions with targets of Al, Au, and Pb. Comparison ...of data for Au+Au and Si+Al indicates that, for the heavier system, there is an increase in the amount of stopping which is accompanied by a decrease in the width of the ital dEsub ital T/ital deta distribution. The ratio of the maximum ital Esub ital T observed for the two systems is significantly greater than the ratio of the total energy available in the center of mass frame.
We present proton and pion tranverse momentum spectra and rapidity distributions for Au+Au collisions at 10.8A GeV/c. The proton spectra exhibit collective transverse flow effects. Evidence of the ...influence of the Coulomb interaction from the fireball is found in the pion transverse momentum spectra. The data are compared with the predictions of the RQMD event generator. (c) 2000 The American Physical Society.
Flow studies at 10.8 GeV/nucleon Hemmick, T.K.; Barrette, J.; Bellwied, R. ...
Nuclear physics. A,
12/1996, Letnik:
610
Journal Article
Recenzirano
We present the present status of the E877 studies of anisotropic transverse flow at the AGS energy. Flow is quantified by Fourier analysis of the azimuthal distributions of transverse energy and ...charged particle multiplicity. Additionally, the mean transverse momentum of identified particle spectra with respect to the reaction plane are measured near the beam rapidity. Analysis shows the presence of nucleon flow at AGS energies and a small pion flow in the direction opposite to that of the nucleon.
We have measured antiproton production cross sections as functions of centrality in collisions of 14.6 GeV/ital c per nucleon sup 28Si ions with targets of Al, Cu, and Pb. For all targets, the ...antiproton yields increase linearly with the number of projectile nucleons that have interacted, and show little target dependence. We discuss the implications of this result on the production and absorption of antiprotons within the nuclear medium.
We have measured cross sections for the synthesis of nuclei of mass ital Ale4 in collisions of 14.6ital A GeV/ital c sup 28Si nuclei with targets of Pb, Cu, and Al. The data are measured at close to ...center-of-mass rapidities, and are unique in their exploration of the centrality dependence of nucleosynthesis. Simple coalescence models that were used to study nucleosynthesis at lower energies are inadequate for the description of our measurements. Our data and improved models are used to extract parameters related to the size of the interaction volume at freeze-out.
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