Kaon production in Au+Au collisions at [Formula Presented]

A systematic study of the spectra and yields of [Formula Presented] and [Formula Presented] is reported by experiment E866 as a function of centrality in Au+Au collisions at [Formula Presented] The invariant transverse spectra for both kaon species are well described by exponentials in [Formula Presented] with inverse slope parameters that are largest at midrapidity and which increase with centrality. The inverse slopes of the [Formula Presented] spectra are slightly larger than the inverse slopes of the [Formula Presented] spectra. The kaon rapidity density peaks at midrapidity with the [Formula Presented] distribution wider in rapidity than [Formula Presented] The integrated total yields of [Formula Presented] and [Formula Presented] increase nonlinearly and steadily with the number of projectile participants. The yield per participant for kaons is two to three times larger than the yield from [Formula Presented] collisions. This enhancement suggests that the majority of kaons in central Au+Au reactions are produced in secondary hadronic collisions. There is no evidence for an onset of additional kaon production from a possible small volume of baryon-rich quark-gluon plasma. The differences between [Formula Presented] and [Formula Presented] rapidity distributions and transverse spectra are consistent with a lower phase space for [Formula Presented] production due to a higher energy threshold. These differences also exclude simple thermal models that assume emission from a common equilibrated system.