Search Results (7 total)

The NA44 experiment has measured single-particle inclusive spectra for charged pions, kaons, and protons as a function of transverse mass near midrapidity in 158A GeV/c Pb+Pb collisions. From the particle mass dependence of the observed m_T distributions, we are able to deduce a value of about 120 MeV for the temperature at thermal freeze-out. From the observed ratios of the rapidity densities, we find values of the chemical potentials for light and strange quarks and a chemical freeze-out temperature of approximately 140 MeV.

NA44 uses a 512-channel Si pad array covering 1.5<η<3.3 to study charged hadron production in 158A GeV Pb+Pb collisions at the CERN SPS. We apply a multiresolution analysis, based on a discrete wavelet transformation, to probe the texture of particle distributions event by event, allowing a simultaneous localization of features in space and scale. Scanning a broad range of multiplicities, we search for signals of clustering and of critical behavior in the power spectra of local density fluctuations. The data are compared with detailed simulations of detector response, using heavy-ion event generators, and with a reference sample created via event mixing. An upper limit is set on the probability and magnitude of dynamical fluctuations.

Two-particle interferometry of positive kaons is studied in Pb+Pb collisions at mean transverse momenta 〈p_T〉≈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.

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.

Two-pion correlations from Pb+Pb collisions at 158 GeV/c per nucleon are measured by the NA44 experiment at CERN. Multidimensional fits characterize the emission volume, which is found to be larger than in S-induced collisions. Comparison to the RQMD model is used to relate the fit parameters to the actual emission volume.

Transverse mass spectra of pions, kaons, and protons from the symmetric heavy-ion collisions 200 A GeV S+S and 158 A GeV Pb+Pb, measured in the NA44 focusing spectrometer at CERN, are presented. The mass dependence of the slope parameters provides evidence of collective transverse flow from expansion of the system in heavy-ion induced central collisions.

The K-shell autoionization probabilities of ⁹⁹Tc, ¹⁴⁷Pm, ¹⁵¹Sm, and ²⁰⁴Tl have been determined to be (3.52 ± 0.20) × 10^-4, (0.936 ± 0.063) × 10^-4, (0.024 ± 0.003) × 10^-4, and (1.22 ± 0.16) × 10^-4, per decay, respectively. The first excited state branching ratios for ¹⁴⁷Pm and ¹⁵¹Sm are (6.48 ± 0.56) × 10^-5 and (0.94 ± 0.06) × 10^-2, respectively. The K-shell electron capture to beta decay ratio for ²⁰⁴Tl is (1.22 ± 0.06) × 10^-2. The autoionization probabilities are compared to the theory of Law and Campbell as modified by Isozumi, Shimizu, and Mukoyama.

RADIOACTIVITY ⁹⁹Tc, ¹⁴⁷Pm, ¹⁵¹Sm, ²⁰⁴Ti, measured P_K, beta and K-shell branching ratios, Si(Li), Ge(Li) detectors.