  We describe compactifications of the moduli spaces of SU(2) monopoles on R3
as manifolds with corners, with respect to which the hyperKaehler metrics admit
asymptotic expansions up to each boundary face. The boundary faces encode
monopoles of charge k decomposing into widely separated monopoles of lower
charge, and the leading order asymptotic of the metric generalizes the one
obtained by Gibbons, Manton and Bielawski in the case of complete decomposition
into monopoles of unit charge. From the structure of the compactifications, we
prove part of Sen's conjecture for the L2 cohomology of the strongly centered
moduli spaces by adapting an argument of Segal and Selby.
