  We analyze the rotational demagnetization of artificial spin ice, a recently
realized array of nanoscale single-domain ferromagnetic islands.
Demagnetization does not anneal this model system into its anti-ferromagnetic
ground state: the moments have a static disordered configuration similar to the
frozen state of the spin ice materials. We demonstrate that this athermal
system has an effective extensive degeneracy and we introduce a formalism that
can predict the populations of local states in this ice-like system with no
adjustable parameters.
