MEASUREMENT OF THE LIFETIME OF HEAVY HYPERNUCLEI PRODUCED IN THE BOMBARDMENT OF BI WITH PROTONS

A very thin Bi target has been installed at the internal beam of COSY- Julich and 1.0 and 1.9 GeV protons have been bumped onto it for determ ination of the background and production of hypernuclei, respectively. With the recoil-shadow method the position distribution of fission fr agments was measured with two multi-wire proportional counters operate d in coincidence. From the distribution recorded in the shadow region and the hypernucleus recoil momenta obtained through BUU calculations, a preliminary value of similar to 145 +/- 7 (stat) +/- 23 (sys) ps wa s obtained for the lifetime of the heavy hypernuclei.