  Following the Non-Relativistic QCD approach we use a gauge invariant smearing
method with factorization to measure the excitation energies for a heavy
$Q\bar{Q}$ system on a $24^3\times 48$ lattice at $\beta=6.2$. The results come
from averaging over an ensemble of 60 QCD configurations. In order to enhance
the signal from each configuration we use wall sources for quark propagators.
The quark Hamiltonian contains only the simplest non-relativistic kinetic
energy term. The results are listed for a range of bare quark masses. The mass
splittings are insensitive to this variable though there are a slight trends
with increasing quark mass. For an appropriate choice of UV cut-off
($a^{-1}=3.2$Gev) the mass spectrum compares reasonably well with the
experimental values for the spin-averaged energy gaps of the $\Upsilon$ system.
We also present results for the $DE$ and $DT$ waves for the lowest bare quark
mass. The results are consistent with degeneracy between the two types of $D$
wave. This encourages the idea that even with our simple quark Hamiltonian the
departure from rotational invariance is not great.
