Thallium doped CsI scintillators are well-regarded for their high light output, relatively fast decay time, and responsiveness to various types of radiation, making them strong candidates for applications in medical imaging, security scanning, high-energy physics, and other radiation detection fields. However, a limitation of CsI(Tl) is its long afterglow, which reduces effectiveness in fast radiographic and radionuclide imaging. This afterglow can lead to pulse pileup in high count-rate situations, diminished energy resolution in nuclear imaging, and artifacts in computed tomography. This study aims to reduce the afterglow effect in CsI(Tl) crystals by introducing Europium as a codopant. As a part of it, CsI(Tl) and CsI(Eu:Tl) Crystals are calibrated and their energy resolutions are determined for standard gamma sources: \(^{133}Ba\) , \(^{137}Cs\) , \(^{22}Na\) , and \(^{60}Co\) .