JOSEMARY ANGELICA CORREA GONCALVES

JOSEMARY ANGELICA CORREA GONCALVES

(Fonte: Lattes)

Resumo

Possui graduação em Física pela Pontifícia Universidade Católica de São Paulo (1987), mestrado em Técnicas e Aplicações Nucleares pelo Instituto de Pesquisas Energéticas e Nucleares (1990), doutorado em Técnicas e Aplicações Nucleares pelo Instituto de Pesquisas Energéticas e Nucleares (1993) e Pós-Doutorado de Curta duração na Universidade de Coimbra com bolsa FAPESP (1997). Foi professora da Pontifícia Universidade Católica de São Paulo entre 1996-2020. Atualmente é pesquisadora titular do Instituto de Pesquisas Energéticas e Nucleares. Tem experiência na área de Engenharia Nuclear, com ênfase em Instrumentação para Medida e Controle de Radiação, atuando principalmente nos seguintes temas: detectores semicondutores de Si, espectrometria e dosimetria de partículas carregadas e radiação eletromagnética, detectores gasosos de catodo resistivo e parâmetros de transporte de elétrons em gases. (Texto extraído do Currículo Lattes em 12 nov. 2021)

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Measurement of the insensitive surface layer thickness of a PIN photodiode based on alpha-particle spectrometry
2022 - PASCOALINO, K.; CAMARGO, F.; GONCALVES, J.A.C.; BUENO, C.C.
In this work, the insensitive layer thickness of a PIN photodiode (SFH206K - Osram) has been measured by varying the incident angle of a collimated monoenergetic alpha particle beam. This technique is based on variations in the path lengths of alpha particles through the insensitive layer and the correspondent energy losses when they impinge on a diode surface at different angles. Therefore, the pulse heights of these alpha particles, closely related to the energies deposited in the active volume of the diode, also depend on their incident angle. So, the difference between the pulse height of alpha particles perpendicularly incident on the diode surface and at any incident angle enables the insensitive layer thickness to be assessed. The result obtained (711  23) nm, less than 1% of the intrinsic layer thickness, besides validating the employed method, demonstrates that the investigated diode is suitable for high resolution charged particle spectrometry.
Dose rate mapping of an industrial 60Co irradiator using an online photodiode-based dosimetry system
2022 - GONCALVES, JOSEMARY A.C.; MANGIAROTTI, ALESSIO; BUENO, CARMEN C.
In this work, a housemade dosimetry system based on a thin photodiode is applied for online mapping of dose rates, between 2.6 and 37.7 Gy/h, delivered by a Panoramic 60Co industrial facility. The operational principle of the dosimeter relies on the real-time acquisition of the induced currents from the irradiated diode operating in the short-circuit mode without externally applied voltage. The radial mapping of the radiation field is performed by rotating the diode around the central axis of the panoramic irradiator, covering 360° at intervals of 18°. The results are benchmarked with alanine dosimeters, Monte Carlo simulations, and reference dose rates retrieved from the facility calibration. The overall consistency of the whole data complies with the maximum response variation (8%, k = 2) recommended by the International Standard Protocols for routine dosimeters in radiation processing dosimetry. It reveals that the photodiode-dosimetry system is a reliable alternative to map dose rate fields and the effectiveness of Monte Carlo simulations as a predictive tool for dose rate measurements in an irradiator.
Characterization of a thin photodiode as a routine dosimeter for low-dose radiation processing applications
2022 - GONCALVES, JOSEMARY A.C.; MANGIAROTTI, ALESSIO; BUENO, CARMEN C.
The characterization of a dosimetry system based on a commercial PIN photodiode as a routine dosimeter in a 60Co industrial facility is reported. The main parameters of the dose rate response (repeatability, reproducibility, and angular dependence) and the dose response (dependence on both dose rate and accumulated dose) are investigated. The results obtained, within a dose rate range of 3.7–52.8 Gy/h and doses up to 200 Gy, fully adhere to the standard protocols established for radiation processing dosimetry. The diode performance as a routine dosimeter is validated by the good overall agreement with radiochromic films and alanine dosimetry.
Measurement of the insensitive surface layer thickness of a PIN photodiode based on alpha-particle spectrometry
2021 - PASCOALINO, K.; GONCALVES, J.A.C.; CAMARGO, F.; BUENO, C.C.
Comparative evaluation of the performance of thin diodes used as on-line dosimeters in radiation processing applications
2021 - GONCALVES, J.A.C.; BUENO, C.C.; MANGIAROTTI, A.
In this work, we report a comparison between the performance of two samples of commercial PIN photodiodes (SFH206K from Osram® and S2506-04 from Hamamatsu®) mainly addressing the variation of their current sensitivities with accumulated dose ranging from 0-15 kGy. All the results so far obtained have revealed that the radiation induced currents are linearly dependent on dose rates from 3.65 to 55.64 Gy/h. The current sensitivity of both unirradiated diodes (0.178 nA.h/Gy.mm3) slightly decreases with accumulated dose, namely 0.32%/kGy (SFH206K) and 1.4%/kGy (S2506-04). Although the SFH206K device compares favorably with the S2506-04, both diodes can be considered as a low budge alternative, good enough for on-line dosimetry applications in the field of radiation processing.
The response of low-cost photodiodes for dosimetry in electron beam processing
2021 - GONCALVES, JOSEMARY A.C.; MANGIAROTTI, ALESSIO; ASFORA, VIVIANE K.; KHOURY, HELEN J.; BUENO, CARMEN C.
The response of thin diodes (SFH206k) as dosimeters has been investigated employing the beam of an electron accelerator within the dose rate range of 2–8 kGy/s and accumulated doses up to 100 kGy. These devices, operating in the short-circuit mode and under industrial irradiation conditions, deliver current signals nonlinearly dependent on the dose rate, whichever the dose history of the diodes, due to the high density of the generated electron-hole pairs herein achieved. Despite this nonlinearity, the dose rate response is stable and characterized by current signals with repeatability better than 2.0%, regardless of the accumulated dose. It is also found that the dose responses are quite linear with sensitivities slightly dependent on the accumulated dose at a constant dose rate. The decrease in the charge sensitivity, taking as reference that obtained before any radiation damage, reaches only 9% (k = 2) at 100 kGy, which is much smaller than the values reported in the literature. From this low aging and the repeatability of both dose rate and dose responses, it seems that the photodiode under investigation is a low budget alternative, good enough for routine dosimetry, provided it has been previously calibrated in the same processing facility.
A low-cost small-size commercial PIN photodiode
2021 - MANGIAROTTI, A.; PETRI, A.R.; MALAFRONTE, A.A.; GONCALVES, J.A.C.; BARROS, S.F.; BUENO, C.C.; FERNANDEZ-VAREA, J.M.; MAIDANA, N.L.; MARTINS, M.N.; VANIN, V.R.
Commercial PIN photodiodes, repurposed as particle detectors, have received a lot of attention along the past decades because they can offer a low-cost solution suitable for several applications. The BPX-65 photodiode has been chosen because of its interesting features for measuring electrons in a harsh radiation environment close to the beam of an accelerator. Its electrical characterisation and its application to photon spectrometry have been presented in the companion paper I. Here, its response function (RF) to electrons is investigated using the beam from an electron accelerator with a small energy spread. The empirical expressions for the RF available in the literature have been improved, simplified, and combined to obtain a final form with 7 free parameters: 4 non-linear and 3 linear. A special fitting procedure, which takes advantage of the presence of the linear parameters, is described. The behaviour of these parameters with beam energy and bias is investigated to uncover the physical origin of the three components included in the proposed RF. The interpretation of the features of the spectra is confirmed by Monte Carlo simulations carried out employing the general-purpose PENELOPE/penEasy package. To take into account the charge-collection properties of the device, a simple model has been implemented and is compared to data. It has then been possible to estimate the thickness of the partially dead layer from the experiment.
A low-cost small-size commercial PIN photodiode
2021 - MALAFRONTE, A.A.; PETRI, A.R.; GONCALVES, J.A.C.; BARROS, S.F.; BUENO, C.C.; MAIDANA, N.L.; MANGIAROTTI, A.; MARTINS, M.N.; QUIVY, A.A.; VANIN, V.R.
Silicon PIN (p-type-intrinsic-n-type) photodiodes are well suited as particle detectors. Here the interest is on a low-cost solution by repurposing a commercial device meant to be used as a light sensor. The intended application is to measure the energy spectra of electrons scattered by thin metallic foils covering small angles close to the beam of the accelerator. The main requirements for a suitable device are: 1) a low-cost solution to allow frequent replacements; 2) a small size to avoid as much as possible an unused area that contributes with unnecessary capacitance; 3) a good energy resolution; and 4) an easy repurposing as a charged-particle detector. The photodiode type BPX 65 manufactured by Osram® fulfils well these requirements. Four samples of these commercial devices have been electrically characterised with respect to reverse current and depleted-region capacitance. At the selected working point of 18 V, comfortably below the maximum rating of 20 V recommended by the manufacturer for continuous operation, the total thickness of the depleted and intrinsic regions is estimated to be (60 ± 3) μm. For the four samples considered, the measured reverse currents for a reverse bias of 18 V are around 0.1 nA, well below the typical value specified by the manufacturer (1 nA). To evaluate the performance of the device as a detector, energy spectra have been acquired for γ-rays with energies from 10 to 140 keV using 241Am, 133Ba, and 57Co radioactive sources. The resolution of the BPX 65 encountered with the γ-rays emitted by 241Am at 59.5-keV is 2.5 keV (FWHM - Full Width at Half Maximum), which is close to the value obtained with a pulser, showing that its main limitation is the electronic chain employed in the setup. The response function to monoenergetic electrons in the same energy range is studied in the companion paper.
Current response stability of a commercial PIN photodiode for low dose radiation processing applications
2020 - GONCALVES, JOSEMARY A.C.; MANGIAROTTI, ALESSIO; BUENO, CARMEN C.
This work investigates the on-line response of a thin diode, for monitoring low dose radiation processing, with respect to the linearity between current and dose-rate, the most interesting part being the variation of the current sensitivity with the accumulated dose. The results obtained indicate that the current response of this diode is linear and quite stable with repeatability better than 0.2% and a slight decay of 5% of the current sensitivity (0.28 nA h/Gy) for doses up to 15 kGy. In an attempt to give theoretical support to these results, the radiation induced current is calculated as a function of the dose rate assuming the diode to be thin as compared with the standard values of the minority carrier diffusion lengths in intrinsic silicon. Agreement within 2% is found between calculations and experimental data.
Count rate effect on the response of a low-cost PIN diode for electron spectrometry
2019 - PETRI, ANNA R.; BARROS, SUELEN F.; GONCALVES, JOSEMARY A.C.; BUENO, CARMEN C.; MAIDANA, NORA; MARTINS, MARCOS N.; VANIN, VITO R.
The response of a low-cost Si photodiode model BPX 65 for low-energy electron spectrometry is investigated envisaging its use in measurements of electron multiple elastic scattering. The electron beam with energy between 10-100 keV is delivered by the gun of the Racetrack Microtron at Instituto de Física, Universidade de São Paulo, with an energy dispersion less than 0.5 keV. The energy resolution achieved was less than 3.5 keV, limited mainly by noise from the electronic acquisition chain. For count rates between 20 and 5500 counts/s, the variation on the centroid of electron peak was smaller than 0.4% throughout the energy range. Therefore, the BPX 65 is suitable for electron spectrometry.