Scintillation response of Europium and Indium-co-doped CsI(Na) single crystal under the exposure of gamma-ray

The traditional CsI(Na) single crystal scintillator was studied to improve its scintillation properties, by co-doping Sodium with Europium and Indium ions. The growth was done by the Czochralski technique. Inductively coupled plasma optical emission spectroscopy and UV spectra including the absorption, excitation, and photoluminescence of the cut ingots were obtained in the region of 200 to 800 nm. The results show that the luminescence intensity of Europium-co-doped CsI(Na) is significantly increased compared to CsI(Na) single crystal, however Indium co-dopant has reduced the CsI(Na) luminescence intensity. Eu's high quantum emission efficiency due to its 4f -> 5d internal transitions and the radiative energy transfer between Na+ and Eu2+ centers are the possible reason for this enhancement. While decreasing the CsI(Na) luminescence intensity, by adding the In co-dopant, is probably due to non-constructive spectral overlap between emission transition of In+ and absorption transition of Na+ which results in non-radiative energy transfer between Na+ and In+. In this regard, the pulse height spectrum of these crystals was determined under the excitation of the gamma-ray sources. It is observed that Eu co-dopant strongly increases the scintillation light yield of the conventional CsI(Na) detector and improves its energy resolution, however In co-doped CsI(Na) reduces scintillation yield.