BIANCA GERALDO
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Resumo IPEN-doc 24575 Eletronic response of photodiode coupled to a boron thin film2017 - 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.Artigo IPEN-doc 24157 Eletronic response of a photodiode coupled to a boron thin film2017 - 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.Artigo IPEN-doc 24097 Production of a square geometry americium standard source for use with photodiodes2017 - COSTA, PRISCILA; GERALDO, BIANCA; RAELE, MARCUS P.; MARUMO, JULIO T.; VICENTE, ROBERTO; ZAHN, GUILHERME S.; GENEZINI, FREDERICO A.In the development of a thermal neutron detector using a square photodiode and a thin boron film, a radioactive calibration source with the same geometry was needed. An americium-243 standard source was produced by electrodeposition aiming at the calibration of a PIN-type silicon photodiode with a detection area of 10 x 10 mm2. To produce the samples two tests were performed. In the first test, a square stainless steel plate (10 x 10 mm2) was fixed on the surface of the conventional plate, which was removed after deposition. To reduce the loss of activity of the source, in the second test nail polish was applied on the silver plate leaving only an area of 10 x 10 mm2 without varnish coating. Once the electrodeposition process was completed, the activity concentration measurement was performed by alpha particle spectrometry. The first method presented a lower activity when compared to the total activity of Am-243 added initially. For the second method, the total activity was concetrated in the exposed square region (without nail polish).The results showed that it is possible to obtain a square geometry source; furthermore, the surrounding nail polish was not contaminated by 243Am. The comparison of these two approaches indicated that the second method was more efficient as it was possible to concentrate all the americium activity in the delimitated square area.