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H G Ritter

Publications and source records attributed to H G Ritter.

7 recordsLinked to original sources
PubMed2003

Near-threshold production of the multistrange Xi- hyperon.

The yield for the multistrange Xi(-) hyperon has been measured in 6A GeV Au+Au collisions via reconstruction of its decay products pi(-) and Lambda, the latter also being reconstructed from its daughter tracks of pi(-) and p. The measurement is rather close to the threshold for Xi(-) production and therefore provides an important test of model predictions. The measured yield for Xi(-) and Lambda are compared for several centralities. In central collisions the Xi(-) yield is found to be in excellent agreement with statistical and transport model predictions, suggesting that multistrange hadron production approaches chemical equilibrium in high baryon density nuclear matter.

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PubMed2003

Comparison of source images for protons, pi-'s, and lambda's in 6A GeV Au+Au collisions.

Source images are extracted from two-particle correlations constructed from strange and nonstrange hadrons produced in 6A GeV Au+Au collisions. Very different source images result from pp vs p Lambda vs pi(-)pi(-) correlations. Scaling by transverse mass can describe the apparent source size ratio for p/pi(-) but not for Lambda/pi(-) or Lambda/p. These observations suggest important differences in the space-time emission histories for protons, pions, and neutral strange baryons produced in the same events.

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PubMed2002

Longitudinal flow of protons from (2-8)A GeV central Au+Au collisions.

Rapidity distributions of protons from central 197Au+197Au collisions measured by the E895 Collaboration in the energy range from (2-8)A GeV at the Brookhaven AGS are presented. Longitudinal flow parameters derived using a thermal model including collective longitudinal expansion are extracted from these distributions. The results show an approximately linear increase in the longitudinal flow velocity, (L), as a function of the logarithm of beam energy.

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PubMed2001

Model-independent source imaging using two-pion correlations in (2 to 8)a GeV Au+Au collisions.

We report a particle source imaging analysis based on two-pion correlations in high multiplicity Au+Au collisions at beam energies between 2A and 8A GeV. We apply the imaging technique introduced by Brown and Danielewicz, which allows a model-independent extraction of source functions with useful accuracy out to relative pion separations of about 20 fm. The extracted source functions have Gaussian shapes. Values of source functions at zero separation are almost constant across the energy range under study. Imaging results are found to be consistent with conventional source parameters obtained from a multidimensional Hanburg-Brown-Twiss analysis.

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PubMed2001

Directed flow of lambda hyperons in (2-6 )A GeV Au+Au collisions.

Directed flow measurements for Lambda hyperons are presented and compared to those for protons produced in the same Au+Au collisions (2A, 4A, and 6A GeV; b<5-6 fm). The measurements indicate that Lambda hyperons flow consistently in the same direction but with smaller magnitudes. A strong positive flow [for Lambdas] has been predicted in calculations which include the influence of the Lambda-nucleon potential. The experimental flow ratio Lambda/p is in qualitative agreement with expectations (approximately 2/3) from the quark counting rule at 2A GeV but is found to decrease with increasing beam energy.

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PubMed2001

Event-by-event fluctuations of the Kaon-to-Pion ratio in central Pb+Pb collisions at 158 GeV per nucleon.

We present the first measurement of fluctuations from event to event in the production of strange particles in collisions of heavy nuclei. The ratio of charged kaons to charged pions is determined for individual central Pb+Pb collisions. After accounting for the fluctuations due to detector resolution and finite number statistics we derive an upper limit on genuine nonstatistical fluctuations, which could be related to a first- or second-order QCD phase transition. Such fluctuations are shown to be very small.

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