Abstract
We investigate a class of 1/2-BPS bubbling
geometries associated to orientifolds of type-IIB string theory and
thereby to excited states of the SO(N)/Sp(N) = 4 supersymmetric Yang-Mills theory. The geometries are in
correspondence with free fermions moving in a harmonic oscillator
potential on the half-line. Branes wrapped on torsion cycles of
these geometries are identified in the fermi fluid
description. Besides being of intrinsic interest, these solutions
may also occur as local geometries in flux compactifications where
orientifold planes are present to ensure global charge
cancellation. We comment on the extension of this procedure to
M-theory orientifolds.