<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Λ</mml:mi></mml:math>Production near Threshold in Central Nucleus-Nucleus Collisions

Abstract

$\ensuremath{\Lambda}$'s produced in central collisions of $^{40}\mathrm{Ar}$+KC1 at 1.8-GeV/u incident energy were detected in a streamer chamber by their charged-particle decay. For central collisions with impact parameters $b&lt;2.4$ fm the $\ensuremath{\Lambda}$ production cross section is 7.6\ifmmode\pm\else\textpm\fi{}2.2 mb. A calculation in which $\ensuremath{\Lambda}$ production occurs in the early stage of the collision qualitatively reproduces the results but underestimates the transverse momenta. An average $\ensuremath{\Lambda}$ polarization of -0.10\ifmmode\pm\else\textpm\fi{}0.05 is observed.