Search for double-{lambda} hypernuclei formation via ({xi}{sup -},{sup 12}C){sub atom}{yields}{sub {lambda}}{sub {lambda}}{sup 12}B+n

Measurement of the energy of neutrons in coincidence with the production of free {xi}{sup -} hyperons can be used to determine the masses of {sub {lambda}}{sub {lambda}}{sup 12}B hypernuclear states and branching ratios of their formation from ({xi}{sup -},{sup 12}C){sub atom}{yields}{sub {lambda}}{sub {lambda}}{sup 12}B+n. The E885 Collaboration utilized the Alternating Gradient Synchrotron 1.8 GeV/c K{sup -} beam incident on a diamond target to accumulate the largest-to-date data sample of (K{sup -},K{sup +}) events. A total of about 3x10{sup 5} (K{sup -},K{sup +}) events have been collected and analyzed. The neutron spectrum shows no apparent peaks from the neutron-emission channel of double-{lambda} hypernuclear formation from ({xi}{sup -},{sup 12}C){sub atom} decay. The upper limit on the branching ratio of the above process has been set to be at or below 4% in the region of expected neutron energies. (c) 2000 The American Physical Society.