We present the abundance analysis for a sample of 18 red giant branch stars in the metal-poor globular cluster NGC 4147 based on medium and high resolution spectra .
This is the first extensive spectroscopic study of this cluster .
We derive abundances of C , N , O , Na , Mg , Al , Si , Ca , Ti , Cr , Fe , Ni , Y , Ba , and Eu .
We find a metallicity of [ Fe/H ] =-1.84 \pm 0.02 and an \alpha -enhancement of +0.38 \pm 0.05 ( errors on the mean ) , typical of halo globular clusters in this metallicity regime .
A significant spread is observed in the abundances of light elements C , N , O , Na , and Al .
In particular we found a Na-O anti-correlation and Na-Al correlation .
The cluster contains only \sim 15 % of stars that belong to the first generation ( Na-poor and O-rich ) .
This implies that it suffered a severe mass loss during its lifetime .
Its [ Ca/Fe ] and [ Ti/Fe ] mean values agree better with the Galactic Halo trend than with the trend of extragalactic environments at the cluster metallicity .
This possibly suggests that NGC 4147 is a genuine Galactic object at odd with what claimed by some author that proposed the cluster to be member of the Sagittarius dwarf galaxy .
A anti-relation between the light s- process element Y and Na may also be present .