The first hypernuclei production experiment using a beam of heavy ions from the Lawrence Berkeley Laboratory Bevatron is described. Mass 16 hypernuclei were produced by 2.1 GeV/ nucleon 0 ions incident on a polyethylene target. These relativistic hypernuclei were studied with large gap spark chambers that were electronically triggered by the low momenturn K' meson produced in association. Analysis of 22 events yields a mean lifetime 7( +) = (0. 86+0'&3&) x 10 sec.NUCLEAR REACTIONS Hypernuclei ( 0, NA or OA) E+, E =2.1 GeV/nucleon, polyethylene target, 0'~roughly measured; mean lifetime of mass 16 hypernuclei measured.

pucker, Phys. Rev. Lett. 16, 746 (1966).A number of experimental studies have been made of the momentum dependence of the total cross section for the reaction ir'p -AK° in the region of incident pion momentum extending from threshold up to and beyond that corresponding to the thresholds for H°K° and Z"if + production. 1 " 8 These studies have sought to clarify the mechanism for AK production near threshold, to search for new resonances, and to find evidence for the predicted cusplike behavior of the total cross section in the region of the UK thresholds. A limitation in previously published studies has been imposed by the uncertainty in the incident pion momentum, typically ±2%, which places a lower limit on the characteristic width of detectable structure of ~20 MeV/c. In the present experiment, the width of detectable structure in the momentum dependence of the total cross section for AK production is reduced to ±1 MeV/c by the use of a spark-chamber spectrometer in the incident pion beam. This apparatus, described elsewhere, 9 permits determination of the momentum of individual incident pions with a relative precision better than ±0.1 %, and with an absolute calibration obtained from kinematic event fitting near the A°K° and H°K° thresholds.

Using the polarized-beam facility at Argonne National Laboratory and a polarized proton target, simultaneous measurements of the spin parameter P and the spin correlation term C, , were made. Data were obtained and analyzed at beam momenta of 2, 3, 4, and 6 GeV/c in the momentum-transfer-squared interval 0.1 5 It/ 5 2.8 (GeV/c)'. A preliminary phase-shift analysis of the 2-and 3-GeV/c data is discussed and a comparison with predictions of a particular Regge-pole model at all four energies is made.