Estudio de las propiedades dosimétricas de topacios sintéticos

Cuando un material dieléctrico o semiconductor es irradiado, las cargas excitadas por la radiación ionizante pueden relajar a través de transiciones radiativas emitiendo luz (radioluminiscencia, RL) o pueden quedar atrapadas en centros metaestables o trampas por tiempos muy largos. Una vez finalizada la irradiación, la relajación radiativa de estas cargas atrapadas puede estimularse aumentando la temperatura del material (termoluminiscencia, TL) o estimulándolo ópticamente (luminiscencia estimulada ópticamente, OSL). Como en general la intensidad de la luz emitida durante la irradiación es proporcional a la tasa de dosis y la emitida durante los procesos de TL u OSL es proporcional a la dosis absorbida, estos fenómenos se han aprovechado tanto en dosimetría personal, ambiental e industrial. Si bien se han estudiado y caracterizado un gran número de materiales luminiscentes, varios de ellos suelen presentar una sub- o sobre- respuesta comparada con la dosis depositada en tejido humano debido a que estos materiales no son tejido-equivalentes (T-E). Esto hace que dichos compuestos se comporten frente a la radiación de manera diferente al tejido tratado, dificultando así su aplicabilidad directa en radioterapia. En este contexto, este trabajo presenta las propiedades dosimétricas de topacios sintéticos para su posible aplicación como dosímetro.Fil: Marcazzo, Salvador Julian. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentin

Photo- and thermally stimulated luminescence of polyminerals extracted from herbs and spices

Ionizing radiation processing is a widely employed method for preservative treatment of foodstuffs. Usually it is possible to detect irradiated herbs and spices by resorting to luminescence techniques, in particular photo- and thermostimulated luminescence. For these techniques to be useful, it is necessary to characterize the response to radiation of each particular herb or spice. In this work, the thermoluminescence (TL) and photostimulated luminescence (PSL) properties of inorganic polymineral fractions extracted from commercial herbs and spices previously irradiated for disinfestation purposes have been analyzed. Samples of mint, cinnamon, chamomile, paprika, black pepper, coriander and Jamaica flower were irradiated from 50 to 400 Gy by using a beta source. The X-ray diffraction (XRD) analysis has shown that the mineral fractions consist mainly of quartz and feldspars. The PSL and TL response as a function of the absorbed dose, and their fading at room temperature have been determined. The TL glow curves have been deconvolved in order to obtain characteristic kinetics parameters in each case. The results of this work show that PSL and TL are reliable techniques for detection and analysis of irradiated foodstuffs.Fil: Cruz Zaragoza, Epifanio. Universidad Nacional Autónoma de México; MéxicoFil: Marcazzo, Salvador Julian. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Chernov, V.. Universidad Nacional Autónoma de México; Méxic

Synthesis of MgB4O7:Dy3+ and Thermoluminescent Characteristics at Low Doses of Beta Radiation

The synthesis and thermoluminescent characteristics of dysprosium-doped MgB4O7 are analyzed. The phosphor at different concentrations (0, 0.1, 0.5, 1, 2 and 4 mol%) of the dopant was prepared by the solution-assisted method. The magnesium borate compound was confirmed by X-ray diffraction. The annealing and dopant concentrations effects on the crystalline matrix were investigated. The highest thermoluminescent sensitivity was found with 450°C of annealing temperature and at high Dy3+ concentration too. The un-doped MgB4O7 phosphor shows a broad glow curve which peaked at 199°C and about 306 °C. Introducing Dy3+ dopant in the matrix that behavior was strongly changed. The wide glow curve shows three glow peaks; two small shoulders at 124 and 195 °C, and a highest peak between 323 and 336 °C temperature range. A large linear dose-response (5 ? 2000 mGy) beta dose was obtained. The complex glow curves were deconvolved and the kinetics parameters were determined considering the general order kinetics model.Fil: Legorreta Alba, Osiel. Universidad Nacional Autónoma de México. Instituto de Ciencias Nucleares; MéxicoFil: Cruz Zaragoza, Epifanio. Universidad Nacional Autónoma de México. Instituto de Ciencias Nucleares; MéxicoFil: Díaz, D.. Universidad Nacional Autónoma de México. Facultad de Química; MéxicoFil: Marcazzo, Salvador Julian. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentin

Synthesis and TL Characterization of Li2B4O7 Doped with Cooper and Manganese

Copper (Cu) and manganese (Mn) doped tissue equivalent Li2B4O7 were prepared by solid state sintering. The glow curves shows a high temperature peak at 222 °C for Li2B4O7:Cu and for Li2B4O7:Mn at 218 °C. Linear dose response is observed up to 140 Gy. With a thermal treatment at 125 °C, the first peak of the phosphors doped with copper (95 °C) and manganese (90 °C) disappears and the main TL peaks remain isolated. The dose rate dependence was studied by exposing the samples at doses of 25 Gy and 250 Gy. At low dose it was observed that the Li2B4O7:Cu TL response has non-dependence on dose rate, and at higher dose was observed that there is a dependence of the TL response with the different dose rateFil: Guarneros Aguilar, C.. Benemérita Universidad Autónoma de Puebla. Facultad de Ciencias Físico-Matemáticas. Posgrado en Física Aplicada; MéxicoFil: Cruz Zaragoza, E.. Universidad Nacional Autónoma de México. Instituto de Ciencias Nucleares. Unidad de Irradiación y Seguridad Radiológica; MicronesiaFil: Marcazzo, Salvador Julian. Universidad Nacional del Centro de la Provincia de Bs.as.. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil; ArgentinaFil: Palomino Merino, R.. Benemérita Universidad Autónoma de Puebla. Facultad de Ciencias Físico-Matemáticas. Posgrado en Física Aplicada; MéxicoFil: Espinosa, J.. Benemérita Universidad Autónoma de Puebla. Facultad de Ciencias Físico-Matemáticas. Posgrado en Física Aplicada; Méxic

OSL, RL and TL characterization of rare-earth ion doped K2YF5: Application in dosimetry

Optically stimulated luminescence (OSL) properties of K2YF5 crystals singly doped with different concentrations of Tb3þions and doubly doped with Tb3þand Ce3þor Tb3þand Dy3þhave been investigated for the first time. Radioluminescence spectra and OSL efficiency for stimulation with different wavelengths of light have been analyzed for each compound. Also, dosimetric characteristics of the most efficient composition, namely K2YF5:1 at.% Tb3þ, have been studied. Finally, the OSL signal peculiarities for K2YF5:1 at.% Tb3þhave been compared to those of a commercial Al2O3:C dosimeter.Fil: Marcazzo, Salvador Julian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física Arroyo Seco; Argentina. Universidad Nacional Autónoma de México; MéxicoFil: Cruz-Zaragoza, E.. Universidad Nacional Autónoma de México; MéxicoFil: Xuan Quang, Vu. Institute of Materials Science; VietnamFil: Khaidukov, N. M.. Institute of General and Inorganic Chemistry; RusiaFil: Santiago, Martin Alejo. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; Argentin

Radioluminescence of rare-earth doped potassium yttrium fluorides crystals

The radioluminescence (RL) properties of K2YF5 crystals doped with Ce3+, Tb3+ and Dy3+ under ionizing irradiation excitation have been studied for the first time. The main objective of this work has been to assess the feasibility of using these crystals as detectors for fiberoptic radioluminescent dosimetry. In particular, it has been found that the RL intensity from both K2YF5:Tb (10%) and K2TbF5 is comparable to that from a commercial Al2O3:C crystal. Longer wavelength emission from these fluorides makes simple optical filtering technique possible to use in order to avoid the stem effect. Afterglow decay times for these fluorides have been found to be similar to that for Al2O3:C and, in particular, K2TbF5 does not show longer afterglow decay time compared to Al2O3:C.Fil: Molina, Pablo Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; ArgentinaFil: Santiago, Martin Alejo. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Marcazzo, Salvador Julian. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Spano, F.. Autoridad Regulatoria Nuclear; ArgentinaFil: Khaidukov, N.. Russian Academy of Sciences; RusiaFil: Caselli, Eduardo Eladio. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; Argentin

Mathematical study of the thermoluminescence process in K2YF5:Tb3+

This paper presents results of studying the simulated thermoluminescence (TL) glow curve in potassium–yttrium double fluoride doped with trivalent optically active Tb3+ ions (K2YF5:Tb3+). Samples have been irradiated with different doses (0.24, 2.4 and 24 Gy) of beta particles. Four trapping states and one kind of recombination-centre model have been used in this simulation. The activation energy and order of kinetics are determined using the general-order kinetic model. The results obtained using the authors’ proposed models were tested and compared with the experimental glow curve of K2YF5:Tb3+. The comparison has shown that the proposed model can predict more accurately and easily the behaviour of the TL glow curve at three different doses.Fil: Kadari, Ahmed. Université Oran; Argelia. Université Ibn Khaldoun; ArgeliaFil: Mostefa, Rabah. Université Oran; ArgeliaFil: Marcazzo, Salvador Julian. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física Arroyo Seco; ArgentinaFil: Kadri, Dahane. Université Oran; Argeli

Thermoluminescent characterization of Al2O3-derived synthetic topaz

Albeit the thermoluminescent properties of both Al2O3 and natural topaz have been documented, owing to a controlled composition, the prospective of synthetic topaz for dosimetry applications is expected to be further promising. In this contribution, the thermoluminescent (Tl) properties of synthetic topaz (Al2F1.44(OH)0.56SiO4) containing materials are reported for the first time. Synthesis tests by chemical vapor deposition (CVD) were conducted using aluminum oxide (Al2O3) and sodium hexafluorosilicate (Na2SiF6) as solid precursor, varying temperature, time, Al2O3 compact angle position, and atmosphere during dwell stage (with and without nitrogen). Subsequently, samples were thermally treated at 500, 600, 700, 750, 800, 850 and 900 °C. Results indicate that samples treated at 800 °C show a standard deviation of 1.2% (SD %) of the area under the glow curve in the range 53–300 °C. Irradiation with 90Sr beta-source of sample A4 (800 °C), from 0.022 Gy to 66 Gy, revealed a nonlinear response, with intensity increasing as doses increase. In addition to the fact that synthesized topaz-containing material possesses a similar Tl intensity compared with that of the commercial dosimeter TLD-100, incidence of the greatest fading (<22%) during the first 20 h suggests its potential application in dosimetry.Fil: Trujillo Vazquez, E.. Instituto Politécnico Nacional; MéxicoFil: Pech Canul, M. I.. Instituto Politécnico Nacional; MéxicoFil: Marcazzo, Salvador Julian. Universidad Nacional del Centro de la Pcia.de Bs.as.. Centro de Investigaciones En Física E Ingeniería del Centro de la Provincia de Buenos Aires. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones En Física E Ingeniería del Centro de la Provincia de Buenos Aires. Provincia de Buenos Aires. Gobernación. Comision de Invest.científicas. Centro de Investigaciones En Física E Ingeniería del Centro de la Provincia D; Argentin

Topaz synthesis using Al2O3, Al(OH)3 or Al2Si2O5(OH)4 and color centers promoting its radioluminescence response

A first study on the radioluminescence (RL) response of topaz synthesized is reported. Using three alternative and different compact reactants separately, i. e., aluminum oxide, aluminum hydroxide and kaolinite, synthesis tests by chemical vapor deposition (CVD) were conducted varying systematically processing temperature and time, incidence angle, and atmosphere. Results show the feasibility to form topaz using the three types of reactants, in varying amounts of 60%, 100% and 47%, respectively. Synthesized topaz exhibits a variety of morphologies: fibers and rectangular bars using Al2O3, cross needle shape compacts using Al(OH)3 and needle-shape phases using Al2Si2O5(OH)4. Irradiation with 90Sr beta-source revealed that only samples prepared using aluminum hydroxide exhibit RL response. The emission band centered at 390 nm of thermally untreated samples and the lack of RL emission of samples treated thermally at 500 °C confirm that the RL response is due to the (H3O4)0 color centers. The RL response showing the highest RL intensity at 390 nm is promoted by processing at 700 °C for 90 min, used for sample H3. A set of reaction pathways for topaz formation using the three alternative compact reactants is proposed.Fil: Trujillo Vazquez, E.. Instituto Politécnico Nacional. Centro de Investigación y de Estudios Avanzados; MéxicoFil: Pech Canul, M. I.. Instituto Politécnico Nacional. Centro de Investigación y de Estudios Avanzados; MéxicoFil: Marcazzo, Salvador Julian. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; Argentin

Modelling the optical bleaching of the thermoluminescence of K 2YF 5:Pr 3+

Optical bleaching of the thermoluminescence (TL) curve of K 2YF 5:Pr 3+ has been observed after optically stimulated luminescence (OSL) readout of pre-irradiated crystals. The traps being responsible for the TL signal are not emptied completely by the optical stimulation. Furthermore, if the illumination time is increased a constant intensity level of the residual TL glow curve is eventually achieved. On the other hand, if the low temperature peak of the glow curve is thermally cleaned, no subsequent OSL is measured. This behavior has been successfully explained by assuming that part of the electrons in the trap being responsible for the low temperature glow peak of K 2YF 5:Pr 3+ recombine with holes via localized transitions during optical stimulation. During TL all trapped electrons recombine via delocalized transitions. Simulations have been carried out in order to demonstrate the feasibility of the model.Fil: Marcazzo, Salvador Julian. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Santiago, Martin Alejo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; ArgentinaFil: Khaidukov, N.. Russian Academy Of Sciences; RusiaFil: Caselli, Eduardo Eladio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; Argentin