We intend to perform some measurements with three NRCA gamma detectors in different geometric configurations in the INES block house in order to get information about the effects of sample position and geometry on the gamma self absorption. The samples we intend to use are a layer of pure copper 100 micron thickness and a layer of reference standard bronze 100 micron thickness and 90 % Cu -10 % Sn composition, both provided by Goodfellow. The layers will be cut in slices 40x40 mm2 and the measurements will be done on a single layer and on multiple layers of the same composition. The self absorption effect will be then characterized as a function of the variation of the peak intensity. The NRCA data will be used to characterize the effect of self absorption of two elements as copper and tin in a solid matrix with different thickness and in different geometry of the detector position.