The CORONAS-PHOTON mission is an observatory class satellite with a large number of scientific payloads to study (i) Solar flares, (ii) Galactic and Extra-galactic sources near the ecliptic plane, (iii) Gamma-ray bursts, and (iv) diffuse cosmic X-ray background. The main goal of the CORONAS-PHOTON mission is to study the Solar hard and electromagnetic radiation in the broad-band energy range from UV to high energy gamma- ray (~2000 MeV). The primary instruments of the mission are high energy radiation spectrometer NATALYA-2M (developed by Russia) and low energy gamma-ray spectrometer RT-2 (developed by India). The RT-2 (Roentzen Telescope) telescope will cover the energy range from 15 to 150 keV. One of the main goal of RT-2 is to image the Solar flares in hard X-ray energy range of 20 keV to 100 keV. The RT-2 Experiment is comprised of 3 detectors namely RT-2/S, RT-2/G (both Phoswich detectors), RT-2/CZT (Solid-state imaging detector) and 1 processing electronics device RT-2/E.