A pion production source using a thin target and a recirculating storage ri
ng is considered. The potential advantages of the scheme are: (i) the thin
target could allow a better collection efficiency; (ii) the proton beam dum
p is avoided; (iii) light targets could be used. The disadvantages are: (i)
the high beam current stored in the recirculator, (ii) constraints on timi
ng. This scheme could be used for the neutrino factory but not for muon col
liders. (C) 2000 Elsevier Science B.V. All rights reserved.