Search for density isomers by observing multiple emission of delayed neutrons

A Pb target was irradiated by /sup 12/C nuclei with energy 43 GeV. The target was periodically placed inside the cavity of a neutron-multiplicity detector which permitted measuring the time spectra for events of multiple emission of delayed neutrons. No anomalous neutron emitters were observed. The upper limits for the probability of their production are estimated for the lifetime range from 10 to 10/sup 5/ sec and various mean neutron multiplicities n-bar. The values obtained lie within the range from 7 x 10/sup -9/ (for n-bar = 12) to 10/sup -6/ (for n-bar = 2).