FABIO EDUARDO DA COSTA

FABIO EDUARDO DA COSTA

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A comparative study on the performance of radiation detectors from the HgI2 crystals grown by different techniques
2011 - MARTINS, J.F.T.; COSTA, F.E.; SANTOS, R.A.; MESQUITA, C.H.; HAMADA, M.M.
There have been attempts to develop room-temperature X- and gamma ray semiconductor detectors for various applications. The main physical semiconductor properties required for fabrication of room temperature semiconductor detectors are: (1) high atomic number; (2) high density; (3) high absorption coefficient; (4) a band gap large enough to keep leakage currents low, at room temperature and (5) large electron and hole mobility-lifetime products, for an efficient charge collection [1, 2]. Among these types of detectors, HgI2 has emerged as a particularly interesting material in view of its wide band gap (2.13 eV) and its large density (7.5 g/cm3 ). HgI2 crystals are composed of high atomic number elements (ZHg=80 and Zi=53) and with high resistivity (>1014 ficm). These are important factors in applications where compact and small thickness detectors are necessary for X- and gamma rays measurements. However, the applications of Hgi2 are limited by the difficulty in obtaining high-quality single crystals and the long-term reliability problems in devices made from crystals [1]. in this work, the Hgi2 crystals were grown using four different techniques: (a) physical vapor transport, (b) solution from dimethyl sulfoxide complexes, (c) vapor growth of HgI2 precipitated from acetone and (d) Bridgman method. The obtained crystals for four methods were characterized considering the following physical chemistry properties: crystal stoichiometry, crystal structure, plan of the crystal orientation, surface morphology of the crystal and crystal impurity. The influence of these physical chemistry properties on the crystals developed by four techniques was studied, evaluating their performance as a radiation detector. The best result of radiation response was found for the crystal grown by physical vapor transport. Also, the dependence of the radiation response on the HgI2 crystal purity was also studied. For this, the HgI2 raw material was purified by the many pass zone refining technique. A significant improvement in the characteristics of the detector-crystal was achieved, when the starting materials became purer.
Development of the mechanical system on a third-generation industrial computed tomography scanner in Brazil
2011 - CALVO, WILSON A.P.; MESQUITA, CARLOS H. de; SPRENGER, FRANCISCO E.; COSTA, FABIO E. da; SALVADOR, PABLO A.V.; CARVALHO, DIEGO V. de S.; HAMADA, MARGARIDA M.
The development of measurement geometry for medical X-ray computed tomography (CT) scanners carried out from the first to the fourth-generation. This concept has also been applied for imaging of industrial processes such as pipe flows or for improving design, operation, optimization and troubleshooting. Nowadays, gamma CT permits to visualize failure equipment points in three-dimensional analysis and in sections of chemical and petrochemical industries. The aim of this work is the development of the mechanical system on a third-generation industrial CT scanner to analyze laboratory gas absorption column which perform highly efficient separation, turning the 60Co, 137Cs or 192Ir sealed gamma-ray source and the NaI(Tl) multidetector array. It has also a translation movement along the column axis to obtain as many slices of the process flow as needed. The mechanical assembly for this third-generation industrial CT scanner is comprised by strength and rigidity structural frame in stainless and carbon steels, rotating table, source shield and collimator with pneumatic exposure system, spur gear system, translator, rotary stage, drives, and stepper motors. The use of suitable spur gears has given a good repeatability and high accuracy in the degree of veracity. The data acquisition boards, mechanical control interfaces, software for movement control and image reconstruction were specially development. This third-generation industrial CT scanner has obtained good spatial resolution and images. The filtered back projection (FBP) tomographic reconstruction algorithm used has shown a faster convergence. The mechanical system presented a good performance in terms of strength, rigidity, accuracy and repeatability with great potential to be used for education or program dedicated to training chemical and petrochemical industry professionals and for industrial process optimization in Brazil.
Obtenção e análise de espectros de energia para detectores de radiação com osciloscópio digital e software tipo planilha eletrônica
2021 - GONCALVES, SILAS A.; CANAZZA, SAMUEL A.; COSTA, FABIO E. da; HAMADA, MARGARIDA M.
Detectores de radiação que produzem um pulso, cuja amplitude é proporcional a energia da radiação incidente, permitem com auxílio de uma eletrônica apropriada e de um analisador multicanal, a obtenção do espectro de energia da radiação incidente sobre o detector. Devido ao analisador multicanal nem sempre estar disponível em laboratórios, este trabalho propõe uma alternativa de medida do espectro utilizando-se dos recursos disponíveis nos osciloscópios digitais de efetuar a medida da amplitude dos pulsos e enviar a um computador tipo PC. No computador, uma planilha eletrônica adequadamente configurada pode então trabalhar os dados coletados no osciloscópio e obter o espectro de energia. Adicionalmente, um segundo recurso permite a seleção temporal da largura do pulso que minimiza leituras incorretas da amplitude na eventualidade de ocorrer empilhamento de pulsos. Para os experimentos foram utilizados um osciloscópio Tektronix TDS 30302B e a planilha eletrônica Excel®. Os espectros foram comparados com os obtidos com um analisador multicanal e se mostraram iguais ou melhores, mas que tiveram como limitação a baixa taxa de aquisição do osciloscópio que foi da ordem de apenas 2 pulsos/seg, portanto milhares de vezes menor que de um analisador multicanal.
Study of the energy spectrum for radiation detectors with digital oscilloscope and worksheet software
2021 - GONÇALVES, S.A.; CANAZZA, S.A.; COSTA, F.E.; HAMADA, M.M.
Portable radiation detector with PIN photodiode for x-rays and CsI(Tl) scintilator with photodiode for gamma rays
2021 - CANAZZA, S.A.; GONÇALVES, S.A.; COSTA, F.E.; HAMADA, M.M.
Desenvolvimento de detector portátil de radiação usando simultaneamente fotodiodo de silício para raios-x e cintilador com fotodiodo para raios gama
2021 - CANAZZA, SAMUEL A.; GONCALVES, SILAS A.; COSTA, FABIO E. da; HAMADA, MARGARIDA M.
Neste trabalho foi desenvolvido um detector portátil de radiação usando como meio detector um fotodiodo de silício para raios-X e um cintilador de CsI(Tl) com fotodiodo para radiação gama. A configuração dos detectores foi estudada utilizando fotodiodos em paralelo com um único pré-amplificador e com pré-amplificadores em paralelo, buscando o menor ruído do conjunto e com isso aumentar a faixa de energias detectadas.
A compact electronic system for a photodiode neutron detector
2019 - COSTA, PRISCILA; RAELE, MARCUS P.; DOMIENIKAN, CLAUDIO; COSTA, FABIO E.; MADI FILHO, TUFIC; ZAHN, GUILHERME S.; GENEZINI, FREDERICO A.
The demand for portable neutron detectors is on the rise, and for that purpose, low cost boron-10 has been frequently used instead of helium-3, which is usually employed in large and expensive detectors. Portable detectors are of interest in some applications, such as neutron dosimeters or inspection systems targeted in the detection of fissile material and drugs in airports. In this work a portable thermal neutron detection system was developed which is based on a commercial silicon photodiode coupled to a boron converter; this prototype is then plugged into a portable electronic system. The boron layer was produced by pulsed laser deposition, either on a thin glass slide or on the photodiode itself. The boron deposition in the photodiode was made directly in the active area of the detector, so before and after the deposition process a characterization of the device regarding both the dark current and the operation voltage was performed using an americium source. Finally, both configurations were tested. The neutron detection process occurs by detecting the alpha and lithium particles produced by the interaction of the incoming neutron with the boron-10 nuclides. These heavy ions then interact with the active area of the reverse-biased photodiode, producing an electric signal that has to be preamplified and then properly amplified by the portable electronic system, which in turn produces an output that can either be sent to a multichannel analyzer or to a digital counter. The integrated circuit of the low noise preamplifier transforms the detector’s current pulse into a voltage pulse with amplitude proportional to the charge carried by the current pulse. The shaper-driver consists of a differentiator and an integrator and is responsible for filtering and further amplifying the preamplifier signal, generating a NIM-compatible energy output pulse. The performance of the photodiode-amplifier set for alpha particles was successively tested using a 243Am radioactive source. Initial tests were made using the boron-deposited glass, and the electronic signal was properly read. However, when the same system was tested using the boron deposited directly in the photodiode, the output signal couldn’t be read, due to the fact that during the deposition process there was an increase in the dark current and a decrease in the operation bias. In this way, a new portable electronic system was developed using a hybrid integrated amplifier circuit. This new electronic setup allowed the use of both configurations, and was tested both with alpha-emitting Americium and neutron-emitting AmBe sources. In conclusion, both portable electronic systems have proven suitable for the thermal neutron detector developed.
Eletronic response of photodiode coupled to a boron thin film
2017 - COSTA, P.; COSTA, F.E.; RAELE, M.P.; ZAHN, G.; GERALDO, B.; VIEIRA JUNIOR, N.D.; SAMAD, R.E.; GENEZINI, F.A.
A portable thermal neutron detector is proposed using a silicon photodiode coupled to a boron thin film. The aim of this work was to verify the effect in the electronic response of this specific photodiode due to boron deposition, since the direct deposition of boron in the semiconductor surface could affect its electrical properties specifically the p-type layer that affects directly the depletion region of the semiconductor reducing the neutron detector efficiency count. Three boron depositions with different thickness were performed in the photodiode (S3590-09) surface by pulsed laser deposition and the photodiode was characterized, before and after the deposition process, using a radioactive americium source. Energy spectra were used to verify the electronic response of the photodiode, due to the fact that it is possible to relate it to the photopeak pulse height and resolution. Spectra from the photodiode without and with boron film deposition were compared and a standard photodiode (S3590-04) that had the electronic signal conserved was used as reference to the pulse height for electronics adjustments. The photopeak energy resolution for the photodiode without boron layer was 10.26%. For the photodiode with boron deposition at different thicknesses, the resolution was: 7.64% (0.14 m), 7.30% (0.44 m) and 6.80% (0.63 m). From these results it is possible to evaluate that there was not any degradation in the silicon photodiode.
Comparative response time and fault logging with a PLC and supervisory software and a standalone unit developed for recording
2017 - BALDACONI, RICARDO H.; COSTA, FABIO E. da
The Cobalt-60 irradiator of IPEN / CNEN, a category IV facility, has a security system for inter locking doors or exposure of radioactive sources made simultaneously by a programmable logic controller (PLC) model S7-200 from Siemens and a relay logic. From a set of information, both systems work together opening doors or exposing the sources. All incoming and outgoing information are sent serially via EIA232 communication to a personal computer with Windows® platform for a supervisory program which provides the monitoring of the entire process by a synoptic table on the computer screen and is also intended to keep records of all events on the computer's hard drive. A deficiency was found for the process of sending events via serial communication (EIA232) from PLC to the supervisory program. When failure occurred in a very short time, the PLC always took the right decision, but the registration process that had to go through the Windows® timeshare lost the information. In the previous work [1] developed a standalone electronics unit connected to the inputs and outputs of the security system, fully optocoupled to avoid any interference to the security system that records each event on a memory card. In this work, for checking the unit developed record time ability, transients incoming signals for simulating failures, were injected at security system inputs and the response time of security system, supervisory program and the autonomous unity were measured and compared.
Eletronic response of a photodiode coupled to a boron thin film
2017 - COSTA, PRISCILA; COSTA, FABIO E.; RAELE, MARCUS P.; ZAHN, GUILHERME S.; GERALDO, BIANCA; VIEIRA JUNIOR, NILSON D.; SAMAD, RICARDO E.; GENEZINI, FREDERICO A.
A portable thermal neutron detector is proposed in this work using a silicon photodiode coupled to a boron thin film. The aim of this work was to verify the effect in the electronic response of this specific photodiode due to boron deposition, since the direct deposition of boron in the semiconductor surface could affect its electrical properties specifically the p-type layer that affects directly the depletion region of the semiconductor reducing the neutron detector efficiency count. Three boron depositions with different thickness were performed in the photodiode (S3590-09) surface by pulsed laser deposition and the photodiode was characterized, before and after the deposition process, using a radioactive americium source. Energy spectra were used to verify the electronic response of the photodiode, due to the fact that it is possible to relate it to the photopeak pulse height and resolution. Spectra from the photodiode without and with boron film deposition were compared and a standard photodiode (S3590-04) that had the electronic signal conserved was used as reference to the pulse height for electronics adjustments. The photopeak energy resolution for the photodiode without boron layer was 10.26%. For the photodiode with boron deposition at different thicknesses, the resolution was: 7.64 % (0.14 μm), 7.30 % (0.44 μm) and 6.80 % (0.63 μm). From these results it is possible to evaluate that there was not any degradation in the silicon photodiode.