20 research outputs found
Differential directed flow in Au+Au collisions
We present experimental data on directed flow in semi-central Au+Au
collisions at incident energies from 90 to 400 A MeV. For the first time for
this energy domain, the data are presented in a transverse momentum
differential way. We study the first order Fourier coefficient v1 for different
particle species and establish a gradual change of its patterns as a function
of incident energy and for different regions in rapidity.Comment: 5 pages, Latex, 5 eps figures, accepted for publication in Phys. Rev.
C (Rapid Communications). Data files available at
http://www-linux.gsi.de/~andronic/fopi/v1.htm
Directed flow in Au+Au, Xe+CsI and Ni+Ni collisions and the nuclear equation of state
We present new experimental data on directed flow in collisions of Au+Au,
Xe+CsI and Ni+Ni at incident energies from 90 to 400A MeV. We study the
centrality and system dependence of integral and differential directed flow for
particles selected according to charge. All the features of the experimental
data are compared with Isospin Quantum Molecular Dynamics (IQMD) model
calculations in an attempt to extract information about the nuclear matter
equation of state (EoS). We show that the combination of rapidity and
transverse momentum analysis of directed flow allow to disentangle various
parametrizations in the model. At 400A MeV, a soft EoS with momentum dependent
interactions is best suited to explain the experimental data in Au+Au and
Xe+CsI, but in case of Ni+Ni the model underpredicts flow for any EoS. At 90A
MeV incident beam energy, none of the IQMD parametrizations studied here is
able to consistently explain the experimental data.Comment: RevTeX, 20 pages, 30 eps figures, accepted for publication in Phys.
Rev. C. Data files available at http://www.gsi.de/~fopiwww/pub
Lambda Hyperons in 2 A*GeV Ni + Cu Collisions
A sample of Lambda's produced in 2 A*GeV Ni + Cu collisions has been obtained
with the EOS Time Projection Chamber at the Bevalac. Low background in the
invariant mass distribution allows for the unambiguous demonstration of Lambda
directed flow. The transverse mass spectrum at mid-rapidity has the
characteristic shoulder-arm shape of particles undergoing radial transverse
expansion. A linear dependence of Lambda multiplicity on impact parameter is
observed, from which a total Lambda + Sigma^0 production cross section of $112
+/- 24 mb is deduced. Detailed comparisons with the ARC and RVUU models are
made.Comment: Revised version accepted for publication in Phys. Lett.
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P-type silicon drift detectors
Preliminary results on 16 CM{sup 2}, position-sensitive silicon drift detectors, fabricated for the first time on p-type silicon substrates, are presented. The detectors were designed, fabricated, and tested recently at LBL and show interesting properties which make them attractive for use in future physics experiments. A pulse count rate of approximately 8 {times} l0{sup 6} s{sup {minus}1} is demonstrated by the p-type silicon drift detectors. This count rate estimate is derived by measuring simultaneous tracks produced by a laser and photolithographic mask collimator that generates double tracks separated by 50 {mu}m to 1200 {mu}m. A new method of using ion-implanted polysilicon to produce precise valued bias resistors on the silicon drift detectors is also discussed
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