Characteristics of Pb²⁺ doped CsI matrix under gamma and neutron excitations

In recent years, there has been an increasing interest in finding new fast scintillating material or improve the characteristics of known scintillators for the demand of high energy physics, industrial and nuclear medical applications. Ions divalent lead Pb²⁺ built in some crystal structures are efficient emission centers and their applications in scintillators was and still is the reason of an intensive study of emission properties of different compounds containing these ions. The aggregation of impurities in CsI is poorly studied. The problem of impurity aggregation in CsI is of interest from point of view of the luminescent properties modification of this scintillation material. In this context, the crystals of Pb²⁺ doped CsI matrix were grown by the vertical Bridgman technique and subjected to annealing in vacuum of 10^-6 mbar and continuous temperature of 350°C, for 24 hours, and then they were employed. To evaluate the response of the CsI:Pb scintillator crystal to gamma radiation, radioactive sources of ¹³⁷Cs (662 keV), ⁶⁰Co (1173 keV and 1333 keV), ²²Na (511 keV and 1275 keV) and ¹³3Ba (355 keV) was used. The operating voltage of the photomultiplier was 2700 V for the detection of gamma rays and the accumulation time in the counting process was 600 s. The crystals used in gamma spectroscopy were cut with dimensions of 20 mm in diameter and 20 mm in height. The scintillator response to neutron radiation from a radioactive source of Am/Be with energy range of 1 MeV to 12 MeV was available. The activity of the AmBe source was 1Ci Am. The fluency was 2.6 x 10⁶ neutrons / second. The operating voltage of the photomultiplier tube was 1300 V. The accumulation time in the counting process was 600 s. The scintillator crystals were cut with dimensions of 20 mm diameter and 10 mm height. With the results obtained, it may be observed that the crystals are sensitive to these radiations. (author)