  We present a chemical abundance study of three inner old halo clusters NGC
6287, NGC 6293, and NGC 6541, finding [Fe/H] = -2.01 +/- 0.05, -1.99 +/- 0.02,
and -1.76 +/- 0.02, respectively, and our metallicity measurements are in good
agreement with previous estimates. The mean alpha-element abundances of our
program clusters are in good agreement with other globular clusters, confirming
previous results. However, the individual alpha-elements appear to follow
different trends. The silicon abundances of the inner halo clusters appear to
be enhanced and the titanium abundances appear to be depleted compared to the
intermediate halo clusters. Our results also appear to oppose to those of
metal-rich bulge giants studied by McWilliam and Rich, who found that bulge
giants are titanium enhanced and silicon deficient. In particular, [Si/Ti]
ratios appear to be related to Galactocentric distances,in the sense that
[Si/Ti] ratios decrease with Galactocentric distance. We propose that
contributions from different masses of the SNe II progenitors that enriched
proto-globular cluster clouds' elemental abundances and the different initial
physical environments surrounding the proto-globular clusters clouds are
responsible for this gradient in [Si/Ti] ratios versus Galactocentric distances
of the "old halo" globular clusters. On the other hand, our program clusters'
enhanced s-process elemental abundances suggest that the formation timescale of
our program clusters might be as short as a few times 10^8 yr after the star
formation is initiated in the Galaxy's central regions, if the s-process site
is intermediate mass AGB stars.
