  We study quenched SU(2) lattice gauge theory with adjoint fermions in a wide
range of temperatures. We focus on spectral quantities of the Dirac operator
and use the temporal fermionic boundary conditions as a tool to probe the
system. We determine the deconfinement temperature through the Polyakov loop,
and the chiral symmetry restoration temperature for adjoint fermions through
the gap in the Dirac spectrum. This chiral transition temperature is about four
times larger than the deconfinement temperature. In between the two transitions
we find that the system is characterized by a non-vanishing chiral condensate
which differs for periodic and anti-periodic fermion boundary conditions. Only
for the latter (physical) boundary conditions, the condensate vanishes at the
chiral transition. The behavior between the two transitions suggests that
deconfinement manifests itself as the onset of a dependence of spectral
quantities of the Dirac operator on boundary conditions. This picture is
supported further by our results for the dual chiral condensate.
