  We present the iron abundance and abundance ratios for 18 elements with
respect to Fe in a sample of stars with a wide range in luminosity from
luminous giants to stars near the turnoff in the globular cluster M5. The
analyzed spectra, obtained with HIRES at the Keck Observatory, are of high
dispersion (R=35,000). We find that the neutron capture, the iron peak and the
alpha-element abundance ratios show no trend with Teff, and low scatter around
the mean between the top of the RGB and near the main sequence turnoff To
within the precision of the measurements (~0.1 dex), gravitationally induced
heavy element diffusion does not appear to be present among the stars near the
main sequence turnoff studied here. Our work and other recent studies suggest
that heavy element diffusion is inhibited in the surface layers of metal poor
stars. Differences in the Na abundance from star to star which extend to the
main sequence turnoff are detected in our sample in M5. The anti-correlation
between O and Na abundances, observed in other metal poor globular clusters, is
not detected in our sample, but it may be hidden among stars with only upper
limits for their O abundances. Overall the abundance ratios of M5 appear very
similar to those of M71, with the possible exception of the neutron capture
element Ba, where we argue that the apparent difference may be due to
difficulties in the analysis. As in M71, the alpha-elements Mg, Ca, Si and Ti
are overabundant relative to Fe. The results of our abundance analysis of 25
stars in M5 provide further evidence of abundance variations among specific
light elements at unexpectedly low luminosities, which cannot be explained by
our current understanding of stellar evolution.
