MARIA DA CONCEICAO COSTA PEREIRA

MARIA DA CONCEICAO COSTA PEREIRA

(Fonte: Lattes)

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Possui graduação em Química Industrial pela Escola Superior de Química Oswaldo Cruz (1984), Mestrado pelo Instituto de Pesquisas Energéticas e Nucleares - USP (1997) e Doutorado pelo Instituto de Pesquisas Energéticas e Nucleares - USP (2006). Atualmente é pesquisadora do Instituto de Pesquisas Energéticas e Nucleares. Possui experiência na área de Química e Engenharia Nuclear, atuando principalmente nos seguintes temas: detectores de radiação, tempo de decaimento de luminescência, cintilação e crescimento de cristais cintiladores inorgânicos. Orientadora de Mestrado (Texto extraído do Currículo Lattes em 16 nov. 2021)

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Zonal refining and Bridgman technique for CsI:Tl scintillation crystal growth
2022 - SUZART, K.F.; PEREIRA, M.C.C.; HAMADA, M.M.; MESQUITA, C.H.
This work describes the development of the crystal cesium iodide doped with thallium (CsI:Tl) for use as a radiation detector. For CsI salt purification the zonal refining methodology using a horizontal oven at a constant temperature of 700 °C was used. The high temperature region corresponds to approximately 10% of the salt bed containing (260 mm). This region moves at a speed of 50 mm/h. The crystal growth was carried out by Bridgman technique, using a vertical oven at speed of 1 mm/h.
Characterization of the CsI(Tl) crystalline scintillating detector produced at IPEN
2021 - SUZART, K.F.; VELO, A.F.; HAMADA, M.M.; PEREIRA, M.C.C.; MESQUITA, C.H.
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.
Growth and optical characteristics of the CsI:Li scintillator crystal for use as radiation detector
2021 - PEREIRA, M.C.C.; FILHO, T.M.; TOMAZ, L.F.; BERRETTA, J.R.
Materials capable of converting ionizing radiation into light photons are called scintillators, some have specific efficiencies for certain applications and types of radiation, e.g. gamma, X-ray, alpha, beta and neutrons. CsI:Tl and NaI:Tl crystals are commonly found in the market because they have several applications, but few studies have been done on lithium doped cesium iodide crystal (CsI:Li). The lithium element, in this crystal used as a dopant, is also exploited as a converter for neutron detection, as it has a shock section of 940 barns for thermal neutrons. The study of the CsI:Li crystal is convenient considering the natural abundance of the lithium element with 7.5%, besides the interest in having a low cost national scintillator material, with an opportunity to search for the response of a detector for different types of radiation. The CsI:Li crystal was grown with molar concentration 10-4 to 10-1, using the vertical Bridgman technique. The parameters involved in the growth process were investigated. The transmittance was evaluated in the spectral region from 190 nm to 1100 nm. Luminescence emission spectra for the CsI:Li crystal were evaluated by photometric analysis of the crystal stimulated with a 137Cs (662 keV) source in front of the coupled sample at the monochromator input. The crystals showed maximum luminescence intensity at the wavelength of 420 nm. It was evaluated the response of the scintillators, when excited with gamma radiation of 241Am, 133Ba, 22Na, 137Cs, 60Co and neutron radiation from the AmBe source, with energy range of 1 MeV to 12 Mev.
Toxicity and color reduction of reactive dyestuff RB 21 and surfactant submitted to electron beam irradiation
2021 - MELO, C.G.; ROSA, J.M.; GARCIA, V.S.G.; BORRELY, S.I.; PEREIRA, M.C.C.
There is an unwelcome reaction between the coloring and the water during the dyeing procedure, a portion of the coloring agent is lost in the bathing and it will compose the final whole effluent. The high absorbance index is related to lost dyestuffs and they also contribute with the toxic effects to the aquatic biota. In addition, these effluents contain large quantity of surfactants applied during dyeing baths, which also contribute to the high toxicity in these samples. The objective of this study was to evaluate electron beam irradiation technology, applied in samples of the Color Index Reactive Blue 21 (RB 21) dyestuff and in samples of surfactant non-ionic and in order to reduce toxicity for both and for RB 21, color reduction. Among the objectives of the study there are the dyestuff exhaustion degree, and some physical-chemical parameters. The acute toxicity assays were carried with Daphnia similis microcrustacean and the results of the dyestuff solution were: the irradiated samples with concentration 0.61 g L-1 did not present significant results, the EC 50 (%) value was to 58.26 for irradiated sample with 2.5 kGy and EC 50 (%) 63.59 for sample irradiated with 5 kGy. The surfactant was more toxic than RB 21, with EC 50 (%) value at 0.42. The color reduction reached 63.30% for the sample of the lowest concentration of effluent. There was a reduction of pH during irradiation.
Characteristics of Pb2+ doped CsI matrix under gamma and neutron excitations
2019 - PEREIRA, MARIA da C.C.; FILHO, TUFIC M.; BERRETTA, JOSE R.; TOMAZ, LUCAS F.; PINTO, MARLENE C.
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 ap-plications. Divalent lead ions Pb2+ built in some crystal structures are efficient emission centers and their appli-cations in scintillators were and are still the reason of an intensive study of emission properties of different com-pounds containing these ions. 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 constant 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) were 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 scintillator response to neutron radiation from a radioactive source of AmBe with energy range of 1 to 12 MeV was available. The activity of the AmBe source was 1 Ci Am. The emission rate was 2.2 x 106 neutrons / second. The operating voltage of the pho-tomultiplier tube was 1300 V. The accumulation time in the counting process was 600 s. With the results obtai-ned, it may be observed that the crystals are sensitive to these radiations.