Two-kaon correlations in central Pb+Pb collisions at 158 a GeV/c

Two-particle interferometry of positive kaons is studied in Pb+Pb collisions at mean transverse momenta approximately 0.25 and 0.91 GeV/c. A three-dimensional analysis was applied to the lower p(T) data, while a two-dimensional analysis was used for the higher p(T) data. We find that the source-size parameters are consistent with the m(T) scaling curve observed in pion-correlation measurements in the same collisions, and that the duration time of kaon emission is consistent with zero within the experimental sensitivity.     

Freeze-out conditions in ultrarelativistic heavy-ion collisions

We present recent results on single particle transverse momentum distributions of pions, kaons and protons, measured in CERN Experiment NA44, of 200 AGeV/c S+S and 158 AGeV/c Pb+Pb central collisions. By comparing these data with thermal and transport models, freeze-out parameters like the temperatureT _fo and the chemical potentials (μ _q ,μ _s ) are extracted and discussed.     

Lambda spectra in 11.6A GeV/c Au-Au collisions

E896 has measured Lambda production in 11.6A GeV/c Au-Au collisions over virtually the whole rapidity phase space. The midrapidity p(t) distributions have been measured for the first time at this energy and appear to indicate that the Lambda hyperons have different freeze-out conditions than protons. A comparison with the relativistic quantum molecular dynamics model shows that while there is good shape agreement at high rapidity the model predicts significantly different slopes of the m(t) spectra at midrapidity. The data, where overlap occurs, are consistent with previously reported measurements.     

New Measurements Concerning a Non-Resonant Photoactivation Cross Section for 115In

In recent years, several groups have reported measurement of a finite non-resonant photoactivation cross section for ¹¹⁵In. Present evaluations of this same parameter have made use of an irradiation arrangement and detector which differ from those of other groups. Our values for the resonant and non-resonant contribution to the photoactivation cross-section are (1.6±0.3)·10^–28 cm² keV and (4.0±0.9)·10^–32 cm², respectively, comparing favourably with counterpart results by TUSTONIC et al.⁵ of (1.3±0.1)·10^–28 cm² keV and (5.5±0.8)·10^–32 cm².     

Antideuteron production in 158A GeV/c Pb + Pb collisions

The invariant cross section as a function of transverse momentum for antideuterons produced in 158A GeV/c per nucleon Pb+Pb central collisions has been measured by the NA44 experiment at CERN. This measurement, together with a measurement of antiprotons, allows for the determination of the antideuteron coalescence parameter. The extracted coalescence radius is found to agree with the deuteron coalescence radius and radii determined from two particle correlations.     

Test of the Pauli exclusion principle for nucleons and atomic electrons by accelerator mass spectrometry

The Pauli exclusion principle was tested by searching with accelerator mass spectrometry for non-Paulian atoms with three electrons in theK-shell and for non-Paulian nuclei with three protons or three neutrons in the nuclear 1 s_1/2 shell. For non-Paulian atoms of and the following limits have been obtained: and . For non-Paulian nuclei of and with three protons or three neutrons, respectively, in the nuclear 1 s_1/2 shell the following limits have been measured: for a range of proton separation energies of between 0 and 50 MeV and for neutron separation energies between 0 and 32 MeV. The result for⁵Li is used to deduce a limit for the probability ²/2 of finding two colliding protons in the symmetric state with respect to exchange to be ²/2<>^–32.Dedicated to Prof. Dr. P. Kienle on the occasion of his 60th birthday. Supported by the BMFT