Metal-rich, Metal-poor: Updated Stellar Population Models for Old
  Stellar Systems
  We present updated stellar population models appropriate for old ages (>1
Gyr) and covering a wide range in metallicities (-1.5<[Fe/H]<0.3). These models
predict the full spectral variation associated with individual element
abundance variation as a function of metallicity and age. The models span the
optical-NIR wavelength range (0.37-2.4um), include a range of initial mass
functions (IMFs) and contain the flexibility to vary 18 individual elements
including C, N, O, Mg, Si, Ca, Ti, and Fe. To test the fidelity of the models
we fit them to integrated light optical spectra of 41 Galactic globular
clusters (GCs). The value of testing models against GCs is that their ages,
metallicities, and detailed abundance patterns have been derived from the HR
diagram in combination with high resolution spectroscopy of individual stars.
We determine stellar population parameters from fits to all wavelengths
simultaneously ("full spectrum fitting"), and demonstrate explicitly with mock
tests that this approach produces smaller uncertainties at fixed S/N ratio than
fitting a standard set of 14 line indices. Comparison of our integrated-light
results to literature values reveals good agreement in metallicity, [Fe/H].
When restricting to GCs without prominent blue horizontal branch populations we
also find good agreement with literature values for ages, [Mg/Fe], [Si/Fe], and
[Ti/Fe].
