We report the main results from experiment WA97 on the production of strange and multistrange hadrons at midrapidity in Pb+Pb, p+Pb and p+Be collisions at 158
A GeV/
c. A comparison with some of the ...available models is presented.
A measurement of strange baryon and antibaryon production in Pb–Pb collisions has been carried out by the NA57 experiment at the CERN SPS, with 40 and 158 AGeV/c beam momentum. Results on Λ, Ξ and Ω ...hyperon yields at mid-rapidity in the most central 53% of Pb–Pb collisions at 40 AGeV/c are presented and compared with those obtained at higher energy, in the same collision centrality range.
The Λ and Ξ− yields per unit rapidity stay roughly constant while those of Ω−, Λ̄, Ξ̄+ and Ω̄+ increase when going to the higher SPS energy. Hyperon yields at the SPS are compared with those from the STAR experiment in sNN=130 GeV Au–Au collisions at RHIC.
K
S
0,
Λ,
Ξ,
Ω and negative particle yields and transverse mass spectra have been measured at central rapidity in Pb–Pb and p–Pb collisions at 158
A GeV/
c. Yields are studied as a function of the ...number of nucleons participating in the collision
N
part, which is estimated with the Glauber model. From p–Pb to Pb–Pb collisions the particle yields per participant increase substantially. The enhancement is more pronounced for multistrange particles, and exceeds an order of magnitude for the
Ω. For a number of participants,
N
part, greater than 100, however, all yields per participant appear to be constant.
The WA97 experiment has measured the transverse mass (
m
T) spectra for negative hadrons (h
−) and strange particles produced at mid-rapidity in Pb−Pb collisions. The increased statistics of analysed ...data samples allowed us to perform a study of the spectra of K
0
S, Λ, Ξ, Ω and h
− as a function of the centrality of the collisions. The data, which correspond to the most central 40% of the total inelastic cross section, have been divided into four centrality classes according to the estimated number of nucleons taking part in the collision. The
m
T spectra, analysed separately for each centrality bin, exhibit only weak (≤ 15%) centrality dependence. The deviation of the Ω inverse slope from the linear dependence on the particle mass is confirmed even for the most central Pb−Pb collisions.
A study of the strangeness enhancement in Lead-Lead collisions with respect to proton-induced reactions is being carried out at the CERN SPS by the WA97 experiment: up to now, data from proton-Lead ...collisions have been used as a reference sample. In this paper we report on a study of particle production in proton-Beryllium collisions. These collisions are expected to constitute a better reference sample than p-Pb, because of the lighter target. The analysis of hyperon and negative particle production is presented and the results are compared with those previously obtained from Pb-Pb and p-Pb collisions.
The WA97 experiment has measured the transverse mass \(({m_{\mathrm T}})\) spectra for negative hadrons (\(\mathrm{h}^-\)) and strange particles produced at mid–rapidity in Pb–Pb collisions. The ...increased statistics of analysed data samples allowed us to perform a study of the spectra of \({\rm K_S^0}\), \(\mathrm{\Lambda}\), \(\mathrm{\Xi}\), \(\mathrm{\Omega}\) and \(\mathrm{h}^-\) as a function of the collision centrality. The data, which correspond to the most central 40% of the total inelastic cross section, have been divided into four centrality classes according to the estimated number of nucleons taking part in the collision. The \(m_{\mathrm T}\) spectra, analysed separately for each centrality bin, exhibit only weak (\(\leq\) 15%) centrality dependence. The deviation of the \(\mathrm{\Omega}\) inverse slope from the linear dependence on the particle mass is confirmed even for the most central Pb–Pb collisions.
Results from NA57 Dainese, A.
Nuclear physics. A,
08/2006, Letnik:
774
Journal Article
Recenzirano
Odprti dostop
The NA57 experiment has measured the production of strange and multi-strange hadrons in heavy-ion collisions at the CERN SPS. After briefly introducing the NA57 apparatus and analysis procedures, we ...present recent results on strangeness enhancement in Pb+Pb relative to p+Be collisions, on the study of the
m
T
distributions of strange particles, and on central-to-peripheral nuclear modification factors in Pb+Pb collisions at top SPS energy.
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