  The neutron long counter NERO was built at the National Superconducting
Cyclotron Laboratory (NSCL), Michigan State University, for measuring
beta-delayed neutron-emission probabilities. The detector was designed to work
in conjunction with a beta-decay implantation station, so that beta decays and
beta-delayed neutrons emitted from implanted nuclei can be measured
simultaneously. The high efficiency of about 40%, for the range of energies of
interest, along with the small background, are crucial for measuring
beta-delayed neutron emission branchings for neutron-rich r-process nuclei
produced as low intensity fragmentation beams in in-flight separator
facilities.
