  The MuCool R&D program is described. The aim of MuCool is to develop all key
pieces of hardware required for ionization cooling of a muon beam. This effort
will lead to a more detailed understanding of the construction and operating
costs of such hardware, as well as to optimized designs that can be used to
build a Neutrino Factory or Muon Collider. This work is being undertaken by a
broad collaboration including physicists and engineers from many national
laboratories and universities in the U.S. and abroad. The intended schedule of
work will lead to ionization cooling being well enough established that a
construction decision for a Neutrino Factory could be taken before the end of
this decade based on a solid technical foundation.
