Chemical Compositions of Field and Globular Cluster RR Lyrae Stars: I.
  NGC 3201
  We present a detailed spectroscopic analysis of horizontal branch stars in
the globular cluster NGC 3201. We collected optical (4580-5330 A), high
resolution (~34,000), high signal-to-noise ratio (~200) spectra for eleven RR
Lyrae stars and one red horizontal branch star with the multifiber spectrograph
M2FS at the 6.5m Magellan telescope at the Las Campanas Observatory. From
measured equivalent widths we derived atmospheric parameters and abundance
ratios for {\alpha} (Mg, Ca, Ti), iron peak (Sc, Cr, Ni, Zn) and s-process (Y)
elements. We found that NGC 3201 is a homogeneous, mono-metallic ([Fe/H]=-1.47
+- 0.04), {\alpha}-enhanced ([{\alpha}/Fe]=0.37 +- 0.04) cluster. The relative
abundances of the iron peak and s-process elements were found to be consistent
with solar values. In comparison with other large stellar samples, NGC 3201 RR
Lyraes have similar chemical enrichment histories as do those of other old
(t>10 Gyr) Halo components (globular clusters, red giants, blue and red
horizontal branch stars, RR Lyraes). We also provided a new average radial
velocity estimate for NGC 3201 by using a template velocity curve to overcome
the limit of single epoch measurements of variable stars: Vrad=494 +- 2 km
s-1({\sigma}=8 km s-1).
