We present a chemical abundance study of three inner old halo clusters NGC 6287 , NGC 6293 , and NGC 6541 , finding [ Fe/H ] = - 2.01 \pm 0.05 , - 1.99 \pm 0.02 , and - 1.76 \pm 0.02 ( internal ) , respectively , and our metallicity measurements are in good agreement with previous estimates .
We also present the radial velocity measurements of the clusters .
Our radial velocity measurements for NGC 6293 and NGC 6541 are in good agreement with previous measurements , however , our radial velocity measurement for NGC 6287 is almost 80 km s ^ { -1 } larger than the previous measurement .

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 .