Köln 2004 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 11: Poster Session: Electromagnetic and Hadronic Probes
HK 11.15: Poster
Tuesday, March 9, 2004, 13:30–15:30, Foyer
Threshold Production of Σ+ at COSY-11 — •T. Rożek — Institue of physics, Silesian University Katowice, IKP Forschungszentrum Jülich
At the cooler synchrotron COSY the threshold production of hyperons has been studied via the pp → p K+ Λ (Σ0) reaction [1] resulting in a cross section ratio R = σ (Λ) / σ (Σ0) of about 28 which exceeds the ratio at high energies by an order of magnitude. Possible explanations within different models are proposed [2] but a definite conclusion is up to now not possible. Further studies in other isospin channels like the Σ+ production will help in the clarification of the relevant dominant reaction mechanisms.
The Σ+ production was measured at the COSY-11 installation via the pp→ nK+Σ+ reaction at Q = 13 MeV and Q = 60 MeV. COSY-11 is an internal magnetic spectrometer experiment at the COoler SYnchroton and storage ring COSY in Jülich. It is equipped with scintillator hodoscopes and drift chambers for charged particle detection and a scintillator/lead sandwich detector for neutrons.
The status of the current analysis will be presented and discussed.
[1] J.T.Balewski et al.,PLB420(1998) 211, S. Sewerin et al.,PRL 83 (1999) 682., P. Kowina, PhD thesis 2002.
[2] A. Gasparian et al., PLB 480 (2000) 273, NPA684:397,2001,
R. Shyam et al., PRC63 (2001) 022202, A. Sibirtsev et al. NPA646 (1999)
427, nucl-th/0004022 v2 (2000).
Supported by Forschungszentrum Jülich.