ABSTRACT We argue the importance of installing at LEAR an internal gas jet target together with a powerful detection system. We discuss an advanced detector which will offer large acceptance and complete information on charged and neutral tracks, in its final implementation. We propose here a phase 1 realisation of this detector which will allow us to carry out a set of fundamental experiments at LEAR during the early operation of ACOL. They comprise studies of .p.p and K\K O s production, on both Wlpolarized and polarized hydrogen targets, over the range 1960 < .Js < 2400 :vleV
