  The quantum resonances of an atom possessing a single valence electron which
shows hyperfine interaction with the nucleus is investigated in the presence of
a three dimensional magnetic quadrupole field. Particular emphasis is put on
the study of the interplay of the hyperfine and quadrupole forces. Analyzing
the underlying Hamiltonian a variety of symmetries are revealed which give rise
to a two-fold degeneracy of the resonance energies. Our numerical approach
employs the complex scaling method and a Sturmian basis set. Several regimes
and classes of short-lived and long-lived resonances are identified. The
energies and decay widths of the resonances are characterized by their
electronic and nuclear spin properties.

Atomic Physics