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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The growth and scintillation characteristics of lithium doped CsI crystals
2011 - PEREIRA, MARIA da C.C.; CARDENAS, JOSE P.N.; MADI FILHO, TUFIC
Inorganic scintillators play an important role in the detection and spectroscopy of gamma and X-rays, as well as in neutrons and charged particles. For a variety of applications, new inorganic scintillation materials are being studied. New scintillation detector applications arise continuously and the interest in the introduction of new fast scintillators becomes relevant. Scintillation crystals based on cesium iodide (CsI) have relatively low hygroscope, easy handling and low cost, features that favor their use as radiation detectors. In this work, lithium doped CsI crystals were grown using the vertical Bridgman technique. In this technique, the charge is maintained at high temperature for 10 h to for the material melting and complete reaction. The temperature gradient 21° C/cm and 1 mm/h descending velocity are chosen as technique parameters. After growth is finished, the furnace is cooled at a rate of 20° C/h to room temperature. The concentration of the lithium doping element (Li) studied was 10-3 M. Analyses were carried out to evaluate the scintillator developed concerning two responses: a) to the gamma radiation, in the energy range of 350 keV to 1330 keV and b) to neutron from AmBe source, with energy range of 1MeV to 12 MeV. T.S. Korolevaa et al [1] describe in their paper about new scintillation materials, for registration of gamma-rays, X-rays, neutrons and neutrinos. One of these materials is 6Li. Lithium can capture neutrons without gamma-ray emission and, thus, reducing the back-ground. The neutron detection reaction is 6Li(n,a)3H with a thermal neutron cross section that 940 barns. In this paper we investigated the feasibility of the CsI:Li crystal as a gamma ray and neutron detector which can be used for monitoring, due to the fact that in our work environment we have two nuclear research reactors, calibration systems and radioisotope production.
Characteristics of PB2+ doped CsI matrix under gamma and neutron excitations
2021 - PEREIRA, MARIA da C.C.; MADI FILHO, TUFIC; BERRETTA, JOSE R.; TOMAZ, LUCAS F.
In recent years, there has been an increasing interest in finding new fast scintillating material or improve the characteristics of known scintillatorsfor the demand of high energy physics, industrial and nuclear medical applications. Divalent lead ions Pb2+ built in some crystal structures are efficient emission centers and their applications in scintillators wereand arestill the reason of an intensive study of emission properties of different compounds containing these ions. In this context, the crystals of Pb2+ doped CsI matrix were grown by the vertical Bridgman techniqueandsubjected to annealing in vacuum of 10-6 mbar and constanttemperatureof 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) wereused. 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 ratewas 2.2x 106 neutrons/ second. The operating voltage of the photomultiplier tube was 1300 V. The accumulation time in the counting process was 600 s. With the results obtained, it may be observed that the crystals are sensitive to these radiations.
Zonal refining and Bridgman technique for CsI:Tl scintillation crystal growth
2021 - SUZART, K.F.; PEREIRA, M.C.C.; HAMADA, M.M.; MESQUITA, C.H.
Development of neutron detector using Li-doped CsI scintillator crystal
2021 - BERRETTA, J.B.; PEREIRA, M.C.C.
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.
Optical properties and radiation response of Li ion-doped CsI scintillator crystal
2019 - PEREIRA, MARIA da C.C.; MADI FILHO, TUFIC; BERRETTA, JOSE R.; TOMAZ, LUCAS F.; MADI, MIRIAM N.
Scintillators are materials that convert the energy of ionizing radiation into a flash of light. Due to the existence of different types of scintillators, they are classified into three groups according to their physicochemical characteristics, namely, inorganic, organic and gaseous scintillators. Among the inorganic crystals, the most frequently used as scintillator consist of alkali metals, in particular alkaline iodides. Scintillation materials have many applications, for instance in medical imaging, security, physics, biology, non-destructive inspection and medicine. In this study, lithium doped CsI scintillator crystals were grown using the vertical Bridgman technique. The concentration of the lithium doping element (Li) studied was 10-4 M to 10-1 M. Analyses were carried out to evaluate the developed scintillators with regard to luminescence emission and optical transmittance. The luminescence emission spectra of these crystals were measured with a monochromator for gamma radiation from 137Cs source excitation. The determination of the dopant distribution along the crystalline axis allowed the identification of the region with Li concentration uniformity, which is the region of the crystalline volume indicated for use as a radiation detector. The crystals were excited with neutron radiation from AmBe source, with the energy range of 1 MeV to 12 MeV. As neutron sources also generate gamma radiation, which can interfere with the measurement, it is necessary that the detector be able to discriminate the presence of such radiation. Accordingly, experiments were performed using gamma radiation in the energy range of 59 keV to 1333 keV in order to verify the ability of the detector to discriminate the presence of different types of radiation.
Study and development of neutron detectors using doped CsI crystals
2019 - MADI FILHO, TUFIC; PEREIRA, MARIA da C.C.; BERRETTA, JOSE R.; TOMAZ, LUCAS F.; MADI, MIRIAM N.
The development of new radiation detectors using scintillation crystals, which increase response speed, dose and energy accuracy and, at the same time, the feasibility of simplifying and reducing costs in the production process are always necessary. In the CTR-IPEN laboratory, pure and doped CsI crystals were grown using the Bridgman technique. This work shows the obtained results using a doped CsI scintillator with the converters: Br, Pb, Tl, Li as alpha, beta, gamma and neutron detectors.
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.
Characteristics of the CsI:Tl scintillator crystal for X-Ray imaging applications
2018 - PEREIRA, MARIA da C.C.; MADI FILHO, TUFIC; BERRETTA, JOSE R.; MESQUITA, CARLOS H. de
Scintillators are high-density luminescent materials that convert X-rays to visible light. Thallium doped cesium iodide (CsI:Tl) scintillation materials are widely used as converters for X-rays into visible light, with very high conversion efficiency of 64.000 optical photons/MeV. CsI:Tl crystals are commercially available, but, the possibility of developing these crystals into different geometric shapes, meeting the need for coupling the photosensor and reducing cost, makes this material very attractive for scientific research. The objective of this work was to study the feasibility of using radiation sensors, scintillators type, developed for use in imaging systems for X-rays. In this paper, the CsI:Tl scintillator crystal with nominal concentration of the 10−3 M was grown by the vertical Bridgman technique. The imaging performance of CsI:Tl scintillator was studied as a function of the design type and thickness, since it interferes with the light scattering and, hence, the detection efficiency plus final image resolution. The result of the diffraction X-ray analysis in the grown crystals was consistent with the pattern of a face-centered cubic (fcc) crystal structure. Slices 25 × 2 × 3 mm3 (length, thickness, height) of the crystal and mini crystals of 1 × 2 × 3 mm3 (length, thickness, height) were used for comparison in the imaging systems for X-rays. With these crystals scintillators, images of undesirable elements, such as metals in food packaging, were obtained. One-dimensional array of photodiodes and the photosensor CCD (Coupled Charge Device) component were used. In order to determine the ideal thickness of the slices of the scintillator crystal CsI:Tl, Monte Carlo method was used.
Characteristics of Pb2+ doped CsI matriz under gamma and neutron excitations
2017 - PEREIRA, MARIA da C.C.; MADI FILHO, TUFIC; 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 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 temperatura 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.