[en] Published in summary form only

[en] Scintillators (i. e. materials that emit light upon interaction with high-energy radiation ) have been in use for a long time, specially after the development of electronic devices capable of amplifying and counting the light produced by them, and new alternatives are still in high demand. One such material are cesium iodine crystals. Pure CsI crystals are poorly hygroscopic, easy to handle and, most importantly, have a short decay time of ~10 ns. However, they have a low light yield, which led to the development of two of its most well known alternatives: Na- and Tl-doped CsI crystals, both of which have a higher light yield than their pure counterpart (~ 65000 ph/MeV for CsI(Tl), for example), at the cost of higher decay times (~ 1300 ns, again for CsI:Tl), limiting their use in applications such as counters. A way to try and remedy this situation is through the doping of CsI crystals with bromide ions. CsI:Br crystals show interesting characteristics. Even though their light yield is lower than that of CsI:Tl and CsI:Na, it’s higher than that of pure CsI. Also, and perhaps most importantly, it’s decay times are much shorter than those of the other two, reaching levels comparable to those of pure CsI depending on the doping element’s concentration[3], as well as having good levels of transmittance and being responsive to alpha, gamma and neutron radiations. More generally, in regards to other scintillators, bromine-doping has recently been shown to enhance the characteristics, notably the light yield and time resolution, of methylammonium lead halide crystals, specially when working at low temperatures[5]. All of this makes the CsI:Br crystal a good candidate for radiation detection when both a sizeable light yield and fast responses are needed. Thus, the goal here is to show a method of growing CsI:Br crystals using the Bridgman technique for use as radiation detectors. (author)

[en] The textile sector stands out for its importance in the global economy and for the high consumption of water in its production processes, mainly in processing. This results from the need for a reaction in an aqueous medium between the fiber and the organic and inorganic inputs. The generated wastewater has high absorciometric rates, due to the hydrolyzed dyestuff present in the dyebath, and several inputs with high solubility and low degradability. Consequently, a colored effluent that is potentially toxic to aquatic biota is generated. The objective of this study was to evaluate the absorciometric index and the toxicity of the textile dyeing effluent, with the Reactive dyestuff Blue 21 (RB 21), before and after the treatment by electron beam irradiation (EBI). (author)

[en] Published in summary form only

[en] An energy spectrometer from 150 keV to 1300 keV with 256 channels was developed , using a PIN photodiode with CsI(Tl) crystal as detector. The equipment must be used with a computer; the best option being a Lap Top or Note Book for constituting a portable spectrometer. The parallel port is used to access the computer, therefore no additional interface is necessary. The monocanal technology controlled by computer is used to simplify the electronic circuits. (author)

No abstract available

[en] During the past 50 years, scintillators have been among the most important nuclear radiation detectors. Inorganic scintillators are widely used in experimental nuclear physics, high energy physics, nuclear medicine, nuclear tomography, environmental studies and many other fields of use. Scintillation crystals based on cesium iodide (CsI) are matters of relatively low hygroscopy, high atomic number, easy handling and low cost, characteristics that favor their use as radiation detectors. In this work, the growth of pure CsI crystals, CsI:Br and CsI:Pb, using the Bridgman technique, is described. Ions of divalent lead (Pb²⁺) doped in the crystal structures are efficient emission centers and their application as scintillators is still the reason for intensive studies. Recently, promising results have been found for crystals of CsI doped by bromine (Br) for their use as radiation detectors. The concentration of the bromine doping element (Br) was studied in the range from 1.5 x 10^-1 M to 10^-2 M and the lead (Pb) in the range from 10^-2 M to 5 x 10^-4 M. To evaluate the scintillators developed, systematic measurements were carried out for luminescence emission and luminescence decay time for gamma radiation, Vickers microhardness assays, and analysis of crystals response to the gamma radiation, in the energy range from 350 keV to 1330 keV, and alpha particles from a ²⁴¹Am source, with energy of 5.54 MeV. The obtained values for luminescence decay time for CsI:Br and CsI:Pb crystals, were from 13 to 19 ns. (authors)

[en] Detergents at waters inducing negative changes for biological degradability and water general quality. Some authors have evidenced a considerable amount of anionic surfactant and toxic effects into natural water and effluents elated to detergents. The objective of the study was to apply electron irradiation for reducing toxicity, and for degradation of surfactants. To quantify surfactant LAS determination as MBAS (methylene blue active substances) was applied. The capacity of radiation to reduce surfactants was evidenced for real effluent and for water solution containing sodium dodecyl sulfate, linear alkylbenzene sulfonate (LAS), separately. An electron beam accelerator (EBA) 1.5 MeV was the radiation source. Anionic surfactant solutions as well as real effluents resulted in less toxic samples after irradiation. Toxicity was evaluated for Vibrio fischeri and Daphnia similis. An important decline of total anionic surfactant was observed after irradiation to doses: 6.0 kGy and 20 kGy (surfactant in water solutions and effluents, respectively). To conclude, EBA irradiations accounted for 88% to 96% less toxic surfactants solutions and effluents and 68% to 96% for MBAS compounds decomposition. (authors)

[en] Cesium iodide crystal activated with thallium (CsI(Tl)) is used as radiation sensor because of its favorable characteristics as scintillator, when excited by gamma radiation. This crystal has good mechanical strength and it is relatively little hygroscopic. In the present work, the CsI(Tl) crystal was grown in the Nuclear Energy Research Institute (IPEN/CNEN/SP) by Brigdman technique, in two different formats: (a) cylindric (∅ 20.1 mm x ↑ 11.9 mm) and (b) parallelepiped (□ 12.3 mm x ↑ 19.5 mm). The scintillator spectrometry was studied through five gamma radiation sources: ⁹⁹mTc (140 keV), ¹³³Ba (355 keV) ²²Na (511 keV) and ¹³⁷Cs (662 keV). The crystals were coupled to a photomultiplier tube using 0.5 McStokes viscosity silicone grease as the optical interface. All electronics for signal measurements were developed at IPEN. Luminescence property of the CsI(Tl) crystal was excited by the radiation from a ¹³⁷Cs source. The energy resolution of the crystalline detector was determined by the FWHM parameter, corresponding to the photopeak width at half of its height. (author)

[en] This work describes the development of the production of the crystal cesium iodide doped with thallium [CsI (Tl)] for use as a radiation detector. For salt purification, zonal refining in a horizontal oven at a constant temperature of 700°C was used. The high temperature region corresponds to approximately 10% of the bed containing the salt (26 centimeters), this region moves with a speed of 5cm/h. The Bridgman technique was used for crystal growth, using a vertical oven whose speed is 1mm/h. (author)